Root/drivers/md/raid5.c

1/*
2 * raid5.c : Multiple Devices driver for Linux
3 * Copyright (C) 1996, 1997 Ingo Molnar, Miguel de Icaza, Gadi Oxman
4 * Copyright (C) 1999, 2000 Ingo Molnar
5 * Copyright (C) 2002, 2003 H. Peter Anvin
6 *
7 * RAID-4/5/6 management functions.
8 * Thanks to Penguin Computing for making the RAID-6 development possible
9 * by donating a test server!
10 *
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License as published by
13 * the Free Software Foundation; either version 2, or (at your option)
14 * any later version.
15 *
16 * You should have received a copy of the GNU General Public License
17 * (for example /usr/src/linux/COPYING); if not, write to the Free
18 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19 */
20
21/*
22 * BITMAP UNPLUGGING:
23 *
24 * The sequencing for updating the bitmap reliably is a little
25 * subtle (and I got it wrong the first time) so it deserves some
26 * explanation.
27 *
28 * We group bitmap updates into batches. Each batch has a number.
29 * We may write out several batches at once, but that isn't very important.
30 * conf->seq_write is the number of the last batch successfully written.
31 * conf->seq_flush is the number of the last batch that was closed to
32 * new additions.
33 * When we discover that we will need to write to any block in a stripe
34 * (in add_stripe_bio) we update the in-memory bitmap and record in sh->bm_seq
35 * the number of the batch it will be in. This is seq_flush+1.
36 * When we are ready to do a write, if that batch hasn't been written yet,
37 * we plug the array and queue the stripe for later.
38 * When an unplug happens, we increment bm_flush, thus closing the current
39 * batch.
40 * When we notice that bm_flush > bm_write, we write out all pending updates
41 * to the bitmap, and advance bm_write to where bm_flush was.
42 * This may occasionally write a bit out twice, but is sure never to
43 * miss any bits.
44 */
45
46#include <linux/blkdev.h>
47#include <linux/kthread.h>
48#include <linux/raid/pq.h>
49#include <linux/async_tx.h>
50#include <linux/module.h>
51#include <linux/async.h>
52#include <linux/seq_file.h>
53#include <linux/cpu.h>
54#include <linux/slab.h>
55#include <linux/ratelimit.h>
56#include <trace/events/block.h>
57
58#include "md.h"
59#include "raid5.h"
60#include "raid0.h"
61#include "bitmap.h"
62
63/*
64 * Stripe cache
65 */
66
67#define NR_STRIPES 256
68#define STRIPE_SIZE PAGE_SIZE
69#define STRIPE_SHIFT (PAGE_SHIFT - 9)
70#define STRIPE_SECTORS (STRIPE_SIZE>>9)
71#define IO_THRESHOLD 1
72#define BYPASS_THRESHOLD 1
73#define NR_HASH (PAGE_SIZE / sizeof(struct hlist_head))
74#define HASH_MASK (NR_HASH - 1)
75
76static inline struct hlist_head *stripe_hash(struct r5conf *conf, sector_t sect)
77{
78    int hash = (sect >> STRIPE_SHIFT) & HASH_MASK;
79    return &conf->stripe_hashtbl[hash];
80}
81
82/* bio's attached to a stripe+device for I/O are linked together in bi_sector
83 * order without overlap. There may be several bio's per stripe+device, and
84 * a bio could span several devices.
85 * When walking this list for a particular stripe+device, we must never proceed
86 * beyond a bio that extends past this device, as the next bio might no longer
87 * be valid.
88 * This function is used to determine the 'next' bio in the list, given the sector
89 * of the current stripe+device
90 */
91static inline struct bio *r5_next_bio(struct bio *bio, sector_t sector)
92{
93    int sectors = bio->bi_size >> 9;
94    if (bio->bi_sector + sectors < sector + STRIPE_SECTORS)
95        return bio->bi_next;
96    else
97        return NULL;
98}
99
100/*
101 * We maintain a biased count of active stripes in the bottom 16 bits of
102 * bi_phys_segments, and a count of processed stripes in the upper 16 bits
103 */
104static inline int raid5_bi_processed_stripes(struct bio *bio)
105{
106    atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
107    return (atomic_read(segments) >> 16) & 0xffff;
108}
109
110static inline int raid5_dec_bi_active_stripes(struct bio *bio)
111{
112    atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
113    return atomic_sub_return(1, segments) & 0xffff;
114}
115
116static inline void raid5_inc_bi_active_stripes(struct bio *bio)
117{
118    atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
119    atomic_inc(segments);
120}
121
122static inline void raid5_set_bi_processed_stripes(struct bio *bio,
123    unsigned int cnt)
124{
125    atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
126    int old, new;
127
128    do {
129        old = atomic_read(segments);
130        new = (old & 0xffff) | (cnt << 16);
131    } while (atomic_cmpxchg(segments, old, new) != old);
132}
133
134static inline void raid5_set_bi_stripes(struct bio *bio, unsigned int cnt)
135{
136    atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
137    atomic_set(segments, cnt);
138}
139
140/* Find first data disk in a raid6 stripe */
141static inline int raid6_d0(struct stripe_head *sh)
142{
143    if (sh->ddf_layout)
144        /* ddf always start from first device */
145        return 0;
146    /* md starts just after Q block */
147    if (sh->qd_idx == sh->disks - 1)
148        return 0;
149    else
150        return sh->qd_idx + 1;
151}
152static inline int raid6_next_disk(int disk, int raid_disks)
153{
154    disk++;
155    return (disk < raid_disks) ? disk : 0;
156}
157
158/* When walking through the disks in a raid5, starting at raid6_d0,
159 * We need to map each disk to a 'slot', where the data disks are slot
160 * 0 .. raid_disks-3, the parity disk is raid_disks-2 and the Q disk
161 * is raid_disks-1. This help does that mapping.
162 */
163static int raid6_idx_to_slot(int idx, struct stripe_head *sh,
164                 int *count, int syndrome_disks)
165{
166    int slot = *count;
167
168    if (sh->ddf_layout)
169        (*count)++;
170    if (idx == sh->pd_idx)
171        return syndrome_disks;
172    if (idx == sh->qd_idx)
173        return syndrome_disks + 1;
174    if (!sh->ddf_layout)
175        (*count)++;
176    return slot;
177}
178
179static void return_io(struct bio *return_bi)
180{
181    struct bio *bi = return_bi;
182    while (bi) {
183
184        return_bi = bi->bi_next;
185        bi->bi_next = NULL;
186        bi->bi_size = 0;
187        trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
188                     bi, 0);
189        bio_endio(bi, 0);
190        bi = return_bi;
191    }
192}
193
194static void print_raid5_conf (struct r5conf *conf);
195
196static int stripe_operations_active(struct stripe_head *sh)
197{
198    return sh->check_state || sh->reconstruct_state ||
199           test_bit(STRIPE_BIOFILL_RUN, &sh->state) ||
200           test_bit(STRIPE_COMPUTE_RUN, &sh->state);
201}
202
203static void do_release_stripe(struct r5conf *conf, struct stripe_head *sh)
204{
205    BUG_ON(!list_empty(&sh->lru));
206    BUG_ON(atomic_read(&conf->active_stripes)==0);
207    if (test_bit(STRIPE_HANDLE, &sh->state)) {
208        if (test_bit(STRIPE_DELAYED, &sh->state) &&
209            !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
210            list_add_tail(&sh->lru, &conf->delayed_list);
211        else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
212               sh->bm_seq - conf->seq_write > 0)
213            list_add_tail(&sh->lru, &conf->bitmap_list);
214        else {
215            clear_bit(STRIPE_DELAYED, &sh->state);
216            clear_bit(STRIPE_BIT_DELAY, &sh->state);
217            list_add_tail(&sh->lru, &conf->handle_list);
218        }
219        md_wakeup_thread(conf->mddev->thread);
220    } else {
221        BUG_ON(stripe_operations_active(sh));
222        if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
223            if (atomic_dec_return(&conf->preread_active_stripes)
224                < IO_THRESHOLD)
225                md_wakeup_thread(conf->mddev->thread);
226        atomic_dec(&conf->active_stripes);
227        if (!test_bit(STRIPE_EXPANDING, &sh->state)) {
228            list_add_tail(&sh->lru, &conf->inactive_list);
229            wake_up(&conf->wait_for_stripe);
230            if (conf->retry_read_aligned)
231                md_wakeup_thread(conf->mddev->thread);
232        }
233    }
234}
235
236static void __release_stripe(struct r5conf *conf, struct stripe_head *sh)
237{
238    if (atomic_dec_and_test(&sh->count))
239        do_release_stripe(conf, sh);
240}
241
242static void release_stripe(struct stripe_head *sh)
243{
244    struct r5conf *conf = sh->raid_conf;
245    unsigned long flags;
246
247    local_irq_save(flags);
248    if (atomic_dec_and_lock(&sh->count, &conf->device_lock)) {
249        do_release_stripe(conf, sh);
250        spin_unlock(&conf->device_lock);
251    }
252    local_irq_restore(flags);
253}
254
255static inline void remove_hash(struct stripe_head *sh)
256{
257    pr_debug("remove_hash(), stripe %llu\n",
258        (unsigned long long)sh->sector);
259
260    hlist_del_init(&sh->hash);
261}
262
263static inline void insert_hash(struct r5conf *conf, struct stripe_head *sh)
264{
265    struct hlist_head *hp = stripe_hash(conf, sh->sector);
266
267    pr_debug("insert_hash(), stripe %llu\n",
268        (unsigned long long)sh->sector);
269
270    hlist_add_head(&sh->hash, hp);
271}
272
273
274/* find an idle stripe, make sure it is unhashed, and return it. */
275static struct stripe_head *get_free_stripe(struct r5conf *conf)
276{
277    struct stripe_head *sh = NULL;
278    struct list_head *first;
279
280    if (list_empty(&conf->inactive_list))
281        goto out;
282    first = conf->inactive_list.next;
283    sh = list_entry(first, struct stripe_head, lru);
284    list_del_init(first);
285    remove_hash(sh);
286    atomic_inc(&conf->active_stripes);
287out:
288    return sh;
289}
290
291static void shrink_buffers(struct stripe_head *sh)
292{
293    struct page *p;
294    int i;
295    int num = sh->raid_conf->pool_size;
296
297    for (i = 0; i < num ; i++) {
298        p = sh->dev[i].page;
299        if (!p)
300            continue;
301        sh->dev[i].page = NULL;
302        put_page(p);
303    }
304}
305
306static int grow_buffers(struct stripe_head *sh)
307{
308    int i;
309    int num = sh->raid_conf->pool_size;
310
311    for (i = 0; i < num; i++) {
312        struct page *page;
313
314        if (!(page = alloc_page(GFP_KERNEL))) {
315            return 1;
316        }
317        sh->dev[i].page = page;
318    }
319    return 0;
320}
321
322static void raid5_build_block(struct stripe_head *sh, int i, int previous);
323static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
324                struct stripe_head *sh);
325
326static void init_stripe(struct stripe_head *sh, sector_t sector, int previous)
327{
328    struct r5conf *conf = sh->raid_conf;
329    int i;
330
331    BUG_ON(atomic_read(&sh->count) != 0);
332    BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
333    BUG_ON(stripe_operations_active(sh));
334
335    pr_debug("init_stripe called, stripe %llu\n",
336        (unsigned long long)sh->sector);
337
338    remove_hash(sh);
339
340    sh->generation = conf->generation - previous;
341    sh->disks = previous ? conf->previous_raid_disks : conf->raid_disks;
342    sh->sector = sector;
343    stripe_set_idx(sector, conf, previous, sh);
344    sh->state = 0;
345
346
347    for (i = sh->disks; i--; ) {
348        struct r5dev *dev = &sh->dev[i];
349
350        if (dev->toread || dev->read || dev->towrite || dev->written ||
351            test_bit(R5_LOCKED, &dev->flags)) {
352            printk(KERN_ERR "sector=%llx i=%d %p %p %p %p %d\n",
353                   (unsigned long long)sh->sector, i, dev->toread,
354                   dev->read, dev->towrite, dev->written,
355                   test_bit(R5_LOCKED, &dev->flags));
356            WARN_ON(1);
357        }
358        dev->flags = 0;
359        raid5_build_block(sh, i, previous);
360    }
361    insert_hash(conf, sh);
362}
363
364static struct stripe_head *__find_stripe(struct r5conf *conf, sector_t sector,
365                     short generation)
366{
367    struct stripe_head *sh;
368
369    pr_debug("__find_stripe, sector %llu\n", (unsigned long long)sector);
370    hlist_for_each_entry(sh, stripe_hash(conf, sector), hash)
371        if (sh->sector == sector && sh->generation == generation)
372            return sh;
373    pr_debug("__stripe %llu not in cache\n", (unsigned long long)sector);
374    return NULL;
375}
376
377/*
378 * Need to check if array has failed when deciding whether to:
379 * - start an array
380 * - remove non-faulty devices
381 * - add a spare
382 * - allow a reshape
383 * This determination is simple when no reshape is happening.
384 * However if there is a reshape, we need to carefully check
385 * both the before and after sections.
386 * This is because some failed devices may only affect one
387 * of the two sections, and some non-in_sync devices may
388 * be insync in the section most affected by failed devices.
389 */
390static int calc_degraded(struct r5conf *conf)
391{
392    int degraded, degraded2;
393    int i;
394
395    rcu_read_lock();
396    degraded = 0;
397    for (i = 0; i < conf->previous_raid_disks; i++) {
398        struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
399        if (rdev && test_bit(Faulty, &rdev->flags))
400            rdev = rcu_dereference(conf->disks[i].replacement);
401        if (!rdev || test_bit(Faulty, &rdev->flags))
402            degraded++;
403        else if (test_bit(In_sync, &rdev->flags))
404            ;
405        else
406            /* not in-sync or faulty.
407             * If the reshape increases the number of devices,
408             * this is being recovered by the reshape, so
409             * this 'previous' section is not in_sync.
410             * If the number of devices is being reduced however,
411             * the device can only be part of the array if
412             * we are reverting a reshape, so this section will
413             * be in-sync.
414             */
415            if (conf->raid_disks >= conf->previous_raid_disks)
416                degraded++;
417    }
418    rcu_read_unlock();
419    if (conf->raid_disks == conf->previous_raid_disks)
420        return degraded;
421    rcu_read_lock();
422    degraded2 = 0;
423    for (i = 0; i < conf->raid_disks; i++) {
424        struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
425        if (rdev && test_bit(Faulty, &rdev->flags))
426            rdev = rcu_dereference(conf->disks[i].replacement);
427        if (!rdev || test_bit(Faulty, &rdev->flags))
428            degraded2++;
429        else if (test_bit(In_sync, &rdev->flags))
430            ;
431        else
432            /* not in-sync or faulty.
433             * If reshape increases the number of devices, this
434             * section has already been recovered, else it
435             * almost certainly hasn't.
436             */
437            if (conf->raid_disks <= conf->previous_raid_disks)
438                degraded2++;
439    }
440    rcu_read_unlock();
441    if (degraded2 > degraded)
442        return degraded2;
443    return degraded;
444}
445
446static int has_failed(struct r5conf *conf)
447{
448    int degraded;
449
450    if (conf->mddev->reshape_position == MaxSector)
451        return conf->mddev->degraded > conf->max_degraded;
452
453    degraded = calc_degraded(conf);
454    if (degraded > conf->max_degraded)
455        return 1;
456    return 0;
457}
458
459static struct stripe_head *
460get_active_stripe(struct r5conf *conf, sector_t sector,
461          int previous, int noblock, int noquiesce)
462{
463    struct stripe_head *sh;
464
465    pr_debug("get_stripe, sector %llu\n", (unsigned long long)sector);
466
467    spin_lock_irq(&conf->device_lock);
468
469    do {
470        wait_event_lock_irq(conf->wait_for_stripe,
471                    conf->quiesce == 0 || noquiesce,
472                    conf->device_lock);
473        sh = __find_stripe(conf, sector, conf->generation - previous);
474        if (!sh) {
475            if (!conf->inactive_blocked)
476                sh = get_free_stripe(conf);
477            if (noblock && sh == NULL)
478                break;
479            if (!sh) {
480                conf->inactive_blocked = 1;
481                wait_event_lock_irq(conf->wait_for_stripe,
482                            !list_empty(&conf->inactive_list) &&
483                            (atomic_read(&conf->active_stripes)
484                             < (conf->max_nr_stripes *3/4)
485                             || !conf->inactive_blocked),
486                            conf->device_lock);
487                conf->inactive_blocked = 0;
488            } else
489                init_stripe(sh, sector, previous);
490        } else {
491            if (atomic_read(&sh->count)) {
492                BUG_ON(!list_empty(&sh->lru)
493                    && !test_bit(STRIPE_EXPANDING, &sh->state)
494                    && !test_bit(STRIPE_ON_UNPLUG_LIST, &sh->state));
495            } else {
496                if (!test_bit(STRIPE_HANDLE, &sh->state))
497                    atomic_inc(&conf->active_stripes);
498                if (list_empty(&sh->lru) &&
499                    !test_bit(STRIPE_EXPANDING, &sh->state))
500                    BUG();
501                list_del_init(&sh->lru);
502            }
503        }
504    } while (sh == NULL);
505
506    if (sh)
507        atomic_inc(&sh->count);
508
509    spin_unlock_irq(&conf->device_lock);
510    return sh;
511}
512
513/* Determine if 'data_offset' or 'new_data_offset' should be used
514 * in this stripe_head.
515 */
516static int use_new_offset(struct r5conf *conf, struct stripe_head *sh)
517{
518    sector_t progress = conf->reshape_progress;
519    /* Need a memory barrier to make sure we see the value
520     * of conf->generation, or ->data_offset that was set before
521     * reshape_progress was updated.
522     */
523    smp_rmb();
524    if (progress == MaxSector)
525        return 0;
526    if (sh->generation == conf->generation - 1)
527        return 0;
528    /* We are in a reshape, and this is a new-generation stripe,
529     * so use new_data_offset.
530     */
531    return 1;
532}
533
534static void
535raid5_end_read_request(struct bio *bi, int error);
536static void
537raid5_end_write_request(struct bio *bi, int error);
538
539static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
540{
541    struct r5conf *conf = sh->raid_conf;
542    int i, disks = sh->disks;
543
544    might_sleep();
545
546    for (i = disks; i--; ) {
547        int rw;
548        int replace_only = 0;
549        struct bio *bi, *rbi;
550        struct md_rdev *rdev, *rrdev = NULL;
551        if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags)) {
552            if (test_and_clear_bit(R5_WantFUA, &sh->dev[i].flags))
553                rw = WRITE_FUA;
554            else
555                rw = WRITE;
556            if (test_bit(R5_Discard, &sh->dev[i].flags))
557                rw |= REQ_DISCARD;
558        } else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
559            rw = READ;
560        else if (test_and_clear_bit(R5_WantReplace,
561                        &sh->dev[i].flags)) {
562            rw = WRITE;
563            replace_only = 1;
564        } else
565            continue;
566        if (test_and_clear_bit(R5_SyncIO, &sh->dev[i].flags))
567            rw |= REQ_SYNC;
568
569        bi = &sh->dev[i].req;
570        rbi = &sh->dev[i].rreq; /* For writing to replacement */
571
572        bi->bi_rw = rw;
573        rbi->bi_rw = rw;
574        if (rw & WRITE) {
575            bi->bi_end_io = raid5_end_write_request;
576            rbi->bi_end_io = raid5_end_write_request;
577        } else
578            bi->bi_end_io = raid5_end_read_request;
579
580        rcu_read_lock();
581        rrdev = rcu_dereference(conf->disks[i].replacement);
582        smp_mb(); /* Ensure that if rrdev is NULL, rdev won't be */
583        rdev = rcu_dereference(conf->disks[i].rdev);
584        if (!rdev) {
585            rdev = rrdev;
586            rrdev = NULL;
587        }
588        if (rw & WRITE) {
589            if (replace_only)
590                rdev = NULL;
591            if (rdev == rrdev)
592                /* We raced and saw duplicates */
593                rrdev = NULL;
594        } else {
595            if (test_bit(R5_ReadRepl, &sh->dev[i].flags) && rrdev)
596                rdev = rrdev;
597            rrdev = NULL;
598        }
599
600        if (rdev && test_bit(Faulty, &rdev->flags))
601            rdev = NULL;
602        if (rdev)
603            atomic_inc(&rdev->nr_pending);
604        if (rrdev && test_bit(Faulty, &rrdev->flags))
605            rrdev = NULL;
606        if (rrdev)
607            atomic_inc(&rrdev->nr_pending);
608        rcu_read_unlock();
609
610        /* We have already checked bad blocks for reads. Now
611         * need to check for writes. We never accept write errors
612         * on the replacement, so we don't to check rrdev.
613         */
614        while ((rw & WRITE) && rdev &&
615               test_bit(WriteErrorSeen, &rdev->flags)) {
616            sector_t first_bad;
617            int bad_sectors;
618            int bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
619                          &first_bad, &bad_sectors);
620            if (!bad)
621                break;
622
623            if (bad < 0) {
624                set_bit(BlockedBadBlocks, &rdev->flags);
625                if (!conf->mddev->external &&
626                    conf->mddev->flags) {
627                    /* It is very unlikely, but we might
628                     * still need to write out the
629                     * bad block log - better give it
630                     * a chance*/
631                    md_check_recovery(conf->mddev);
632                }
633                /*
634                 * Because md_wait_for_blocked_rdev
635                 * will dec nr_pending, we must
636                 * increment it first.
637                 */
638                atomic_inc(&rdev->nr_pending);
639                md_wait_for_blocked_rdev(rdev, conf->mddev);
640            } else {
641                /* Acknowledged bad block - skip the write */
642                rdev_dec_pending(rdev, conf->mddev);
643                rdev = NULL;
644            }
645        }
646
647        if (rdev) {
648            if (s->syncing || s->expanding || s->expanded
649                || s->replacing)
650                md_sync_acct(rdev->bdev, STRIPE_SECTORS);
651
652            set_bit(STRIPE_IO_STARTED, &sh->state);
653
654            bi->bi_bdev = rdev->bdev;
655            pr_debug("%s: for %llu schedule op %ld on disc %d\n",
656                __func__, (unsigned long long)sh->sector,
657                bi->bi_rw, i);
658            atomic_inc(&sh->count);
659            if (use_new_offset(conf, sh))
660                bi->bi_sector = (sh->sector
661                         + rdev->new_data_offset);
662            else
663                bi->bi_sector = (sh->sector
664                         + rdev->data_offset);
665            if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
666                bi->bi_rw |= REQ_FLUSH;
667
668            bi->bi_flags = 1 << BIO_UPTODATE;
669            bi->bi_idx = 0;
670            bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
671            bi->bi_io_vec[0].bv_offset = 0;
672            bi->bi_size = STRIPE_SIZE;
673            bi->bi_next = NULL;
674            if (rrdev)
675                set_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags);
676
677            if (conf->mddev->gendisk)
678                trace_block_bio_remap(bdev_get_queue(bi->bi_bdev),
679                              bi, disk_devt(conf->mddev->gendisk),
680                              sh->dev[i].sector);
681            generic_make_request(bi);
682        }
683        if (rrdev) {
684            if (s->syncing || s->expanding || s->expanded
685                || s->replacing)
686                md_sync_acct(rrdev->bdev, STRIPE_SECTORS);
687
688            set_bit(STRIPE_IO_STARTED, &sh->state);
689
690            rbi->bi_bdev = rrdev->bdev;
691            pr_debug("%s: for %llu schedule op %ld on "
692                 "replacement disc %d\n",
693                __func__, (unsigned long long)sh->sector,
694                rbi->bi_rw, i);
695            atomic_inc(&sh->count);
696            if (use_new_offset(conf, sh))
697                rbi->bi_sector = (sh->sector
698                          + rrdev->new_data_offset);
699            else
700                rbi->bi_sector = (sh->sector
701                          + rrdev->data_offset);
702            rbi->bi_flags = 1 << BIO_UPTODATE;
703            rbi->bi_idx = 0;
704            rbi->bi_io_vec[0].bv_len = STRIPE_SIZE;
705            rbi->bi_io_vec[0].bv_offset = 0;
706            rbi->bi_size = STRIPE_SIZE;
707            rbi->bi_next = NULL;
708            if (conf->mddev->gendisk)
709                trace_block_bio_remap(bdev_get_queue(rbi->bi_bdev),
710                              rbi, disk_devt(conf->mddev->gendisk),
711                              sh->dev[i].sector);
712            generic_make_request(rbi);
713        }
714        if (!rdev && !rrdev) {
715            if (rw & WRITE)
716                set_bit(STRIPE_DEGRADED, &sh->state);
717            pr_debug("skip op %ld on disc %d for sector %llu\n",
718                bi->bi_rw, i, (unsigned long long)sh->sector);
719            clear_bit(R5_LOCKED, &sh->dev[i].flags);
720            set_bit(STRIPE_HANDLE, &sh->state);
721        }
722    }
723}
724
725static struct dma_async_tx_descriptor *
726async_copy_data(int frombio, struct bio *bio, struct page *page,
727    sector_t sector, struct dma_async_tx_descriptor *tx)
728{
729    struct bio_vec *bvl;
730    struct page *bio_page;
731    int i;
732    int page_offset;
733    struct async_submit_ctl submit;
734    enum async_tx_flags flags = 0;
735
736    if (bio->bi_sector >= sector)
737        page_offset = (signed)(bio->bi_sector - sector) * 512;
738    else
739        page_offset = (signed)(sector - bio->bi_sector) * -512;
740
741    if (frombio)
742        flags |= ASYNC_TX_FENCE;
743    init_async_submit(&submit, flags, tx, NULL, NULL, NULL);
744
745    bio_for_each_segment(bvl, bio, i) {
746        int len = bvl->bv_len;
747        int clen;
748        int b_offset = 0;
749
750        if (page_offset < 0) {
751            b_offset = -page_offset;
752            page_offset += b_offset;
753            len -= b_offset;
754        }
755
756        if (len > 0 && page_offset + len > STRIPE_SIZE)
757            clen = STRIPE_SIZE - page_offset;
758        else
759            clen = len;
760
761        if (clen > 0) {
762            b_offset += bvl->bv_offset;
763            bio_page = bvl->bv_page;
764            if (frombio)
765                tx = async_memcpy(page, bio_page, page_offset,
766                          b_offset, clen, &submit);
767            else
768                tx = async_memcpy(bio_page, page, b_offset,
769                          page_offset, clen, &submit);
770        }
771        /* chain the operations */
772        submit.depend_tx = tx;
773
774        if (clen < len) /* hit end of page */
775            break;
776        page_offset += len;
777    }
778
779    return tx;
780}
781
782static void ops_complete_biofill(void *stripe_head_ref)
783{
784    struct stripe_head *sh = stripe_head_ref;
785    struct bio *return_bi = NULL;
786    int i;
787
788    pr_debug("%s: stripe %llu\n", __func__,
789        (unsigned long long)sh->sector);
790
791    /* clear completed biofills */
792    for (i = sh->disks; i--; ) {
793        struct r5dev *dev = &sh->dev[i];
794
795        /* acknowledge completion of a biofill operation */
796        /* and check if we need to reply to a read request,
797         * new R5_Wantfill requests are held off until
798         * !STRIPE_BIOFILL_RUN
799         */
800        if (test_and_clear_bit(R5_Wantfill, &dev->flags)) {
801            struct bio *rbi, *rbi2;
802
803            BUG_ON(!dev->read);
804            rbi = dev->read;
805            dev->read = NULL;
806            while (rbi && rbi->bi_sector <
807                dev->sector + STRIPE_SECTORS) {
808                rbi2 = r5_next_bio(rbi, dev->sector);
809                if (!raid5_dec_bi_active_stripes(rbi)) {
810                    rbi->bi_next = return_bi;
811                    return_bi = rbi;
812                }
813                rbi = rbi2;
814            }
815        }
816    }
817    clear_bit(STRIPE_BIOFILL_RUN, &sh->state);
818
819    return_io(return_bi);
820
821    set_bit(STRIPE_HANDLE, &sh->state);
822    release_stripe(sh);
823}
824
825static void ops_run_biofill(struct stripe_head *sh)
826{
827    struct dma_async_tx_descriptor *tx = NULL;
828    struct async_submit_ctl submit;
829    int i;
830
831    pr_debug("%s: stripe %llu\n", __func__,
832        (unsigned long long)sh->sector);
833
834    for (i = sh->disks; i--; ) {
835        struct r5dev *dev = &sh->dev[i];
836        if (test_bit(R5_Wantfill, &dev->flags)) {
837            struct bio *rbi;
838            spin_lock_irq(&sh->stripe_lock);
839            dev->read = rbi = dev->toread;
840            dev->toread = NULL;
841            spin_unlock_irq(&sh->stripe_lock);
842            while (rbi && rbi->bi_sector <
843                dev->sector + STRIPE_SECTORS) {
844                tx = async_copy_data(0, rbi, dev->page,
845                    dev->sector, tx);
846                rbi = r5_next_bio(rbi, dev->sector);
847            }
848        }
849    }
850
851    atomic_inc(&sh->count);
852    init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_biofill, sh, NULL);
853    async_trigger_callback(&submit);
854}
855
856static void mark_target_uptodate(struct stripe_head *sh, int target)
857{
858    struct r5dev *tgt;
859
860    if (target < 0)
861        return;
862
863    tgt = &sh->dev[target];
864    set_bit(R5_UPTODATE, &tgt->flags);
865    BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
866    clear_bit(R5_Wantcompute, &tgt->flags);
867}
868
869static void ops_complete_compute(void *stripe_head_ref)
870{
871    struct stripe_head *sh = stripe_head_ref;
872
873    pr_debug("%s: stripe %llu\n", __func__,
874        (unsigned long long)sh->sector);
875
876    /* mark the computed target(s) as uptodate */
877    mark_target_uptodate(sh, sh->ops.target);
878    mark_target_uptodate(sh, sh->ops.target2);
879
880    clear_bit(STRIPE_COMPUTE_RUN, &sh->state);
881    if (sh->check_state == check_state_compute_run)
882        sh->check_state = check_state_compute_result;
883    set_bit(STRIPE_HANDLE, &sh->state);
884    release_stripe(sh);
885}
886
887/* return a pointer to the address conversion region of the scribble buffer */
888static addr_conv_t *to_addr_conv(struct stripe_head *sh,
889                 struct raid5_percpu *percpu)
890{
891    return percpu->scribble + sizeof(struct page *) * (sh->disks + 2);
892}
893
894static struct dma_async_tx_descriptor *
895ops_run_compute5(struct stripe_head *sh, struct raid5_percpu *percpu)
896{
897    int disks = sh->disks;
898    struct page **xor_srcs = percpu->scribble;
899    int target = sh->ops.target;
900    struct r5dev *tgt = &sh->dev[target];
901    struct page *xor_dest = tgt->page;
902    int count = 0;
903    struct dma_async_tx_descriptor *tx;
904    struct async_submit_ctl submit;
905    int i;
906
907    pr_debug("%s: stripe %llu block: %d\n",
908        __func__, (unsigned long long)sh->sector, target);
909    BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
910
911    for (i = disks; i--; )
912        if (i != target)
913            xor_srcs[count++] = sh->dev[i].page;
914
915    atomic_inc(&sh->count);
916
917    init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST, NULL,
918              ops_complete_compute, sh, to_addr_conv(sh, percpu));
919    if (unlikely(count == 1))
920        tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
921    else
922        tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
923
924    return tx;
925}
926
927/* set_syndrome_sources - populate source buffers for gen_syndrome
928 * @srcs - (struct page *) array of size sh->disks
929 * @sh - stripe_head to parse
930 *
931 * Populates srcs in proper layout order for the stripe and returns the
932 * 'count' of sources to be used in a call to async_gen_syndrome. The P
933 * destination buffer is recorded in srcs[count] and the Q destination
934 * is recorded in srcs[count+1]].
935 */
936static int set_syndrome_sources(struct page **srcs, struct stripe_head *sh)
937{
938    int disks = sh->disks;
939    int syndrome_disks = sh->ddf_layout ? disks : (disks - 2);
940    int d0_idx = raid6_d0(sh);
941    int count;
942    int i;
943
944    for (i = 0; i < disks; i++)
945        srcs[i] = NULL;
946
947    count = 0;
948    i = d0_idx;
949    do {
950        int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
951
952        srcs[slot] = sh->dev[i].page;
953        i = raid6_next_disk(i, disks);
954    } while (i != d0_idx);
955
956    return syndrome_disks;
957}
958
959static struct dma_async_tx_descriptor *
960ops_run_compute6_1(struct stripe_head *sh, struct raid5_percpu *percpu)
961{
962    int disks = sh->disks;
963    struct page **blocks = percpu->scribble;
964    int target;
965    int qd_idx = sh->qd_idx;
966    struct dma_async_tx_descriptor *tx;
967    struct async_submit_ctl submit;
968    struct r5dev *tgt;
969    struct page *dest;
970    int i;
971    int count;
972
973    if (sh->ops.target < 0)
974        target = sh->ops.target2;
975    else if (sh->ops.target2 < 0)
976        target = sh->ops.target;
977    else
978        /* we should only have one valid target */
979        BUG();
980    BUG_ON(target < 0);
981    pr_debug("%s: stripe %llu block: %d\n",
982        __func__, (unsigned long long)sh->sector, target);
983
984    tgt = &sh->dev[target];
985    BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
986    dest = tgt->page;
987
988    atomic_inc(&sh->count);
989
990    if (target == qd_idx) {
991        count = set_syndrome_sources(blocks, sh);
992        blocks[count] = NULL; /* regenerating p is not necessary */
993        BUG_ON(blocks[count+1] != dest); /* q should already be set */
994        init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
995                  ops_complete_compute, sh,
996                  to_addr_conv(sh, percpu));
997        tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE, &submit);
998    } else {
999        /* Compute any data- or p-drive using XOR */
1000        count = 0;
1001        for (i = disks; i-- ; ) {
1002            if (i == target || i == qd_idx)
1003                continue;
1004            blocks[count++] = sh->dev[i].page;
1005        }
1006
1007        init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1008                  NULL, ops_complete_compute, sh,
1009                  to_addr_conv(sh, percpu));
1010        tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE, &submit);
1011    }
1012
1013    return tx;
1014}
1015
1016static struct dma_async_tx_descriptor *
1017ops_run_compute6_2(struct stripe_head *sh, struct raid5_percpu *percpu)
1018{
1019    int i, count, disks = sh->disks;
1020    int syndrome_disks = sh->ddf_layout ? disks : disks-2;
1021    int d0_idx = raid6_d0(sh);
1022    int faila = -1, failb = -1;
1023    int target = sh->ops.target;
1024    int target2 = sh->ops.target2;
1025    struct r5dev *tgt = &sh->dev[target];
1026    struct r5dev *tgt2 = &sh->dev[target2];
1027    struct dma_async_tx_descriptor *tx;
1028    struct page **blocks = percpu->scribble;
1029    struct async_submit_ctl submit;
1030
1031    pr_debug("%s: stripe %llu block1: %d block2: %d\n",
1032         __func__, (unsigned long long)sh->sector, target, target2);
1033    BUG_ON(target < 0 || target2 < 0);
1034    BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1035    BUG_ON(!test_bit(R5_Wantcompute, &tgt2->flags));
1036
1037    /* we need to open-code set_syndrome_sources to handle the
1038     * slot number conversion for 'faila' and 'failb'
1039     */
1040    for (i = 0; i < disks ; i++)
1041        blocks[i] = NULL;
1042    count = 0;
1043    i = d0_idx;
1044    do {
1045        int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1046
1047        blocks[slot] = sh->dev[i].page;
1048
1049        if (i == target)
1050            faila = slot;
1051        if (i == target2)
1052            failb = slot;
1053        i = raid6_next_disk(i, disks);
1054    } while (i != d0_idx);
1055
1056    BUG_ON(faila == failb);
1057    if (failb < faila)
1058        swap(faila, failb);
1059    pr_debug("%s: stripe: %llu faila: %d failb: %d\n",
1060         __func__, (unsigned long long)sh->sector, faila, failb);
1061
1062    atomic_inc(&sh->count);
1063
1064    if (failb == syndrome_disks+1) {
1065        /* Q disk is one of the missing disks */
1066        if (faila == syndrome_disks) {
1067            /* Missing P+Q, just recompute */
1068            init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1069                      ops_complete_compute, sh,
1070                      to_addr_conv(sh, percpu));
1071            return async_gen_syndrome(blocks, 0, syndrome_disks+2,
1072                          STRIPE_SIZE, &submit);
1073        } else {
1074            struct page *dest;
1075            int data_target;
1076            int qd_idx = sh->qd_idx;
1077
1078            /* Missing D+Q: recompute D from P, then recompute Q */
1079            if (target == qd_idx)
1080                data_target = target2;
1081            else
1082                data_target = target;
1083
1084            count = 0;
1085            for (i = disks; i-- ; ) {
1086                if (i == data_target || i == qd_idx)
1087                    continue;
1088                blocks[count++] = sh->dev[i].page;
1089            }
1090            dest = sh->dev[data_target].page;
1091            init_async_submit(&submit,
1092                      ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1093                      NULL, NULL, NULL,
1094                      to_addr_conv(sh, percpu));
1095            tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE,
1096                       &submit);
1097
1098            count = set_syndrome_sources(blocks, sh);
1099            init_async_submit(&submit, ASYNC_TX_FENCE, tx,
1100                      ops_complete_compute, sh,
1101                      to_addr_conv(sh, percpu));
1102            return async_gen_syndrome(blocks, 0, count+2,
1103                          STRIPE_SIZE, &submit);
1104        }
1105    } else {
1106        init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1107                  ops_complete_compute, sh,
1108                  to_addr_conv(sh, percpu));
1109        if (failb == syndrome_disks) {
1110            /* We're missing D+P. */
1111            return async_raid6_datap_recov(syndrome_disks+2,
1112                               STRIPE_SIZE, faila,
1113                               blocks, &submit);
1114        } else {
1115            /* We're missing D+D. */
1116            return async_raid6_2data_recov(syndrome_disks+2,
1117                               STRIPE_SIZE, faila, failb,
1118                               blocks, &submit);
1119        }
1120    }
1121}
1122
1123
1124static void ops_complete_prexor(void *stripe_head_ref)
1125{
1126    struct stripe_head *sh = stripe_head_ref;
1127
1128    pr_debug("%s: stripe %llu\n", __func__,
1129        (unsigned long long)sh->sector);
1130}
1131
1132static struct dma_async_tx_descriptor *
1133ops_run_prexor(struct stripe_head *sh, struct raid5_percpu *percpu,
1134           struct dma_async_tx_descriptor *tx)
1135{
1136    int disks = sh->disks;
1137    struct page **xor_srcs = percpu->scribble;
1138    int count = 0, pd_idx = sh->pd_idx, i;
1139    struct async_submit_ctl submit;
1140
1141    /* existing parity data subtracted */
1142    struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1143
1144    pr_debug("%s: stripe %llu\n", __func__,
1145        (unsigned long long)sh->sector);
1146
1147    for (i = disks; i--; ) {
1148        struct r5dev *dev = &sh->dev[i];
1149        /* Only process blocks that are known to be uptodate */
1150        if (test_bit(R5_Wantdrain, &dev->flags))
1151            xor_srcs[count++] = dev->page;
1152    }
1153
1154    init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
1155              ops_complete_prexor, sh, to_addr_conv(sh, percpu));
1156    tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1157
1158    return tx;
1159}
1160
1161static struct dma_async_tx_descriptor *
1162ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
1163{
1164    int disks = sh->disks;
1165    int i;
1166
1167    pr_debug("%s: stripe %llu\n", __func__,
1168        (unsigned long long)sh->sector);
1169
1170    for (i = disks; i--; ) {
1171        struct r5dev *dev = &sh->dev[i];
1172        struct bio *chosen;
1173
1174        if (test_and_clear_bit(R5_Wantdrain, &dev->flags)) {
1175            struct bio *wbi;
1176
1177            spin_lock_irq(&sh->stripe_lock);
1178            chosen = dev->towrite;
1179            dev->towrite = NULL;
1180            BUG_ON(dev->written);
1181            wbi = dev->written = chosen;
1182            spin_unlock_irq(&sh->stripe_lock);
1183
1184            while (wbi && wbi->bi_sector <
1185                dev->sector + STRIPE_SECTORS) {
1186                if (wbi->bi_rw & REQ_FUA)
1187                    set_bit(R5_WantFUA, &dev->flags);
1188                if (wbi->bi_rw & REQ_SYNC)
1189                    set_bit(R5_SyncIO, &dev->flags);
1190                if (wbi->bi_rw & REQ_DISCARD)
1191                    set_bit(R5_Discard, &dev->flags);
1192                else
1193                    tx = async_copy_data(1, wbi, dev->page,
1194                        dev->sector, tx);
1195                wbi = r5_next_bio(wbi, dev->sector);
1196            }
1197        }
1198    }
1199
1200    return tx;
1201}
1202
1203static void ops_complete_reconstruct(void *stripe_head_ref)
1204{
1205    struct stripe_head *sh = stripe_head_ref;
1206    int disks = sh->disks;
1207    int pd_idx = sh->pd_idx;
1208    int qd_idx = sh->qd_idx;
1209    int i;
1210    bool fua = false, sync = false, discard = false;
1211
1212    pr_debug("%s: stripe %llu\n", __func__,
1213        (unsigned long long)sh->sector);
1214
1215    for (i = disks; i--; ) {
1216        fua |= test_bit(R5_WantFUA, &sh->dev[i].flags);
1217        sync |= test_bit(R5_SyncIO, &sh->dev[i].flags);
1218        discard |= test_bit(R5_Discard, &sh->dev[i].flags);
1219    }
1220
1221    for (i = disks; i--; ) {
1222        struct r5dev *dev = &sh->dev[i];
1223
1224        if (dev->written || i == pd_idx || i == qd_idx) {
1225            if (!discard)
1226                set_bit(R5_UPTODATE, &dev->flags);
1227            if (fua)
1228                set_bit(R5_WantFUA, &dev->flags);
1229            if (sync)
1230                set_bit(R5_SyncIO, &dev->flags);
1231        }
1232    }
1233
1234    if (sh->reconstruct_state == reconstruct_state_drain_run)
1235        sh->reconstruct_state = reconstruct_state_drain_result;
1236    else if (sh->reconstruct_state == reconstruct_state_prexor_drain_run)
1237        sh->reconstruct_state = reconstruct_state_prexor_drain_result;
1238    else {
1239        BUG_ON(sh->reconstruct_state != reconstruct_state_run);
1240        sh->reconstruct_state = reconstruct_state_result;
1241    }
1242
1243    set_bit(STRIPE_HANDLE, &sh->state);
1244    release_stripe(sh);
1245}
1246
1247static void
1248ops_run_reconstruct5(struct stripe_head *sh, struct raid5_percpu *percpu,
1249             struct dma_async_tx_descriptor *tx)
1250{
1251    int disks = sh->disks;
1252    struct page **xor_srcs = percpu->scribble;
1253    struct async_submit_ctl submit;
1254    int count = 0, pd_idx = sh->pd_idx, i;
1255    struct page *xor_dest;
1256    int prexor = 0;
1257    unsigned long flags;
1258
1259    pr_debug("%s: stripe %llu\n", __func__,
1260        (unsigned long long)sh->sector);
1261
1262    for (i = 0; i < sh->disks; i++) {
1263        if (pd_idx == i)
1264            continue;
1265        if (!test_bit(R5_Discard, &sh->dev[i].flags))
1266            break;
1267    }
1268    if (i >= sh->disks) {
1269        atomic_inc(&sh->count);
1270        set_bit(R5_Discard, &sh->dev[pd_idx].flags);
1271        ops_complete_reconstruct(sh);
1272        return;
1273    }
1274    /* check if prexor is active which means only process blocks
1275     * that are part of a read-modify-write (written)
1276     */
1277    if (sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
1278        prexor = 1;
1279        xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1280        for (i = disks; i--; ) {
1281            struct r5dev *dev = &sh->dev[i];
1282            if (dev->written)
1283                xor_srcs[count++] = dev->page;
1284        }
1285    } else {
1286        xor_dest = sh->dev[pd_idx].page;
1287        for (i = disks; i--; ) {
1288            struct r5dev *dev = &sh->dev[i];
1289            if (i != pd_idx)
1290                xor_srcs[count++] = dev->page;
1291        }
1292    }
1293
1294    /* 1/ if we prexor'd then the dest is reused as a source
1295     * 2/ if we did not prexor then we are redoing the parity
1296     * set ASYNC_TX_XOR_DROP_DST and ASYNC_TX_XOR_ZERO_DST
1297     * for the synchronous xor case
1298     */
1299    flags = ASYNC_TX_ACK |
1300        (prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST);
1301
1302    atomic_inc(&sh->count);
1303
1304    init_async_submit(&submit, flags, tx, ops_complete_reconstruct, sh,
1305              to_addr_conv(sh, percpu));
1306    if (unlikely(count == 1))
1307        tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
1308    else
1309        tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1310}
1311
1312static void
1313ops_run_reconstruct6(struct stripe_head *sh, struct raid5_percpu *percpu,
1314             struct dma_async_tx_descriptor *tx)
1315{
1316    struct async_submit_ctl submit;
1317    struct page **blocks = percpu->scribble;
1318    int count, i;
1319
1320    pr_debug("%s: stripe %llu\n", __func__, (unsigned long long)sh->sector);
1321
1322    for (i = 0; i < sh->disks; i++) {
1323        if (sh->pd_idx == i || sh->qd_idx == i)
1324            continue;
1325        if (!test_bit(R5_Discard, &sh->dev[i].flags))
1326            break;
1327    }
1328    if (i >= sh->disks) {
1329        atomic_inc(&sh->count);
1330        set_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
1331        set_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
1332        ops_complete_reconstruct(sh);
1333        return;
1334    }
1335
1336    count = set_syndrome_sources(blocks, sh);
1337
1338    atomic_inc(&sh->count);
1339
1340    init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_reconstruct,
1341              sh, to_addr_conv(sh, percpu));
1342    async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE, &submit);
1343}
1344
1345static void ops_complete_check(void *stripe_head_ref)
1346{
1347    struct stripe_head *sh = stripe_head_ref;
1348
1349    pr_debug("%s: stripe %llu\n", __func__,
1350        (unsigned long long)sh->sector);
1351
1352    sh->check_state = check_state_check_result;
1353    set_bit(STRIPE_HANDLE, &sh->state);
1354    release_stripe(sh);
1355}
1356
1357static void ops_run_check_p(struct stripe_head *sh, struct raid5_percpu *percpu)
1358{
1359    int disks = sh->disks;
1360    int pd_idx = sh->pd_idx;
1361    int qd_idx = sh->qd_idx;
1362    struct page *xor_dest;
1363    struct page **xor_srcs = percpu->scribble;
1364    struct dma_async_tx_descriptor *tx;
1365    struct async_submit_ctl submit;
1366    int count;
1367    int i;
1368
1369    pr_debug("%s: stripe %llu\n", __func__,
1370        (unsigned long long)sh->sector);
1371
1372    count = 0;
1373    xor_dest = sh->dev[pd_idx].page;
1374    xor_srcs[count++] = xor_dest;
1375    for (i = disks; i--; ) {
1376        if (i == pd_idx || i == qd_idx)
1377            continue;
1378        xor_srcs[count++] = sh->dev[i].page;
1379    }
1380
1381    init_async_submit(&submit, 0, NULL, NULL, NULL,
1382              to_addr_conv(sh, percpu));
1383    tx = async_xor_val(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
1384               &sh->ops.zero_sum_result, &submit);
1385
1386    atomic_inc(&sh->count);
1387    init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_check, sh, NULL);
1388    tx = async_trigger_callback(&submit);
1389}
1390
1391static void ops_run_check_pq(struct stripe_head *sh, struct raid5_percpu *percpu, int checkp)
1392{
1393    struct page **srcs = percpu->scribble;
1394    struct async_submit_ctl submit;
1395    int count;
1396
1397    pr_debug("%s: stripe %llu checkp: %d\n", __func__,
1398        (unsigned long long)sh->sector, checkp);
1399
1400    count = set_syndrome_sources(srcs, sh);
1401    if (!checkp)
1402        srcs[count] = NULL;
1403
1404    atomic_inc(&sh->count);
1405    init_async_submit(&submit, ASYNC_TX_ACK, NULL, ops_complete_check,
1406              sh, to_addr_conv(sh, percpu));
1407    async_syndrome_val(srcs, 0, count+2, STRIPE_SIZE,
1408               &sh->ops.zero_sum_result, percpu->spare_page, &submit);
1409}
1410
1411static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
1412{
1413    int overlap_clear = 0, i, disks = sh->disks;
1414    struct dma_async_tx_descriptor *tx = NULL;
1415    struct r5conf *conf = sh->raid_conf;
1416    int level = conf->level;
1417    struct raid5_percpu *percpu;
1418    unsigned long cpu;
1419
1420    cpu = get_cpu();
1421    percpu = per_cpu_ptr(conf->percpu, cpu);
1422    if (test_bit(STRIPE_OP_BIOFILL, &ops_request)) {
1423        ops_run_biofill(sh);
1424        overlap_clear++;
1425    }
1426
1427    if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request)) {
1428        if (level < 6)
1429            tx = ops_run_compute5(sh, percpu);
1430        else {
1431            if (sh->ops.target2 < 0 || sh->ops.target < 0)
1432                tx = ops_run_compute6_1(sh, percpu);
1433            else
1434                tx = ops_run_compute6_2(sh, percpu);
1435        }
1436        /* terminate the chain if reconstruct is not set to be run */
1437        if (tx && !test_bit(STRIPE_OP_RECONSTRUCT, &ops_request))
1438            async_tx_ack(tx);
1439    }
1440
1441    if (test_bit(STRIPE_OP_PREXOR, &ops_request))
1442        tx = ops_run_prexor(sh, percpu, tx);
1443
1444    if (test_bit(STRIPE_OP_BIODRAIN, &ops_request)) {
1445        tx = ops_run_biodrain(sh, tx);
1446        overlap_clear++;
1447    }
1448
1449    if (test_bit(STRIPE_OP_RECONSTRUCT, &ops_request)) {
1450        if (level < 6)
1451            ops_run_reconstruct5(sh, percpu, tx);
1452        else
1453            ops_run_reconstruct6(sh, percpu, tx);
1454    }
1455
1456    if (test_bit(STRIPE_OP_CHECK, &ops_request)) {
1457        if (sh->check_state == check_state_run)
1458            ops_run_check_p(sh, percpu);
1459        else if (sh->check_state == check_state_run_q)
1460            ops_run_check_pq(sh, percpu, 0);
1461        else if (sh->check_state == check_state_run_pq)
1462            ops_run_check_pq(sh, percpu, 1);
1463        else
1464            BUG();
1465    }
1466
1467    if (overlap_clear)
1468        for (i = disks; i--; ) {
1469            struct r5dev *dev = &sh->dev[i];
1470            if (test_and_clear_bit(R5_Overlap, &dev->flags))
1471                wake_up(&sh->raid_conf->wait_for_overlap);
1472        }
1473    put_cpu();
1474}
1475
1476static int grow_one_stripe(struct r5conf *conf)
1477{
1478    struct stripe_head *sh;
1479    sh = kmem_cache_zalloc(conf->slab_cache, GFP_KERNEL);
1480    if (!sh)
1481        return 0;
1482
1483    sh->raid_conf = conf;
1484
1485    spin_lock_init(&sh->stripe_lock);
1486
1487    if (grow_buffers(sh)) {
1488        shrink_buffers(sh);
1489        kmem_cache_free(conf->slab_cache, sh);
1490        return 0;
1491    }
1492    /* we just created an active stripe so... */
1493    atomic_set(&sh->count, 1);
1494    atomic_inc(&conf->active_stripes);
1495    INIT_LIST_HEAD(&sh->lru);
1496    release_stripe(sh);
1497    return 1;
1498}
1499
1500static int grow_stripes(struct r5conf *conf, int num)
1501{
1502    struct kmem_cache *sc;
1503    int devs = max(conf->raid_disks, conf->previous_raid_disks);
1504
1505    if (conf->mddev->gendisk)
1506        sprintf(conf->cache_name[0],
1507            "raid%d-%s", conf->level, mdname(conf->mddev));
1508    else
1509        sprintf(conf->cache_name[0],
1510            "raid%d-%p", conf->level, conf->mddev);
1511    sprintf(conf->cache_name[1], "%s-alt", conf->cache_name[0]);
1512
1513    conf->active_name = 0;
1514    sc = kmem_cache_create(conf->cache_name[conf->active_name],
1515                   sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
1516                   0, 0, NULL);
1517    if (!sc)
1518        return 1;
1519    conf->slab_cache = sc;
1520    conf->pool_size = devs;
1521    while (num--)
1522        if (!grow_one_stripe(conf))
1523            return 1;
1524    return 0;
1525}
1526
1527/**
1528 * scribble_len - return the required size of the scribble region
1529 * @num - total number of disks in the array
1530 *
1531 * The size must be enough to contain:
1532 * 1/ a struct page pointer for each device in the array +2
1533 * 2/ room to convert each entry in (1) to its corresponding dma
1534 * (dma_map_page()) or page (page_address()) address.
1535 *
1536 * Note: the +2 is for the destination buffers of the ddf/raid6 case where we
1537 * calculate over all devices (not just the data blocks), using zeros in place
1538 * of the P and Q blocks.
1539 */
1540static size_t scribble_len(int num)
1541{
1542    size_t len;
1543
1544    len = sizeof(struct page *) * (num+2) + sizeof(addr_conv_t) * (num+2);
1545
1546    return len;
1547}
1548
1549static int resize_stripes(struct r5conf *conf, int newsize)
1550{
1551    /* Make all the stripes able to hold 'newsize' devices.
1552     * New slots in each stripe get 'page' set to a new page.
1553     *
1554     * This happens in stages:
1555     * 1/ create a new kmem_cache and allocate the required number of
1556     * stripe_heads.
1557     * 2/ gather all the old stripe_heads and transfer the pages across
1558     * to the new stripe_heads. This will have the side effect of
1559     * freezing the array as once all stripe_heads have been collected,
1560     * no IO will be possible. Old stripe heads are freed once their
1561     * pages have been transferred over, and the old kmem_cache is
1562     * freed when all stripes are done.
1563     * 3/ reallocate conf->disks to be suitable bigger. If this fails,
1564     * we simple return a failre status - no need to clean anything up.
1565     * 4/ allocate new pages for the new slots in the new stripe_heads.
1566     * If this fails, we don't bother trying the shrink the
1567     * stripe_heads down again, we just leave them as they are.
1568     * As each stripe_head is processed the new one is released into
1569     * active service.
1570     *
1571     * Once step2 is started, we cannot afford to wait for a write,
1572     * so we use GFP_NOIO allocations.
1573     */
1574    struct stripe_head *osh, *nsh;
1575    LIST_HEAD(newstripes);
1576    struct disk_info *ndisks;
1577    unsigned long cpu;
1578    int err;
1579    struct kmem_cache *sc;
1580    int i;
1581
1582    if (newsize <= conf->pool_size)
1583        return 0; /* never bother to shrink */
1584
1585    err = md_allow_write(conf->mddev);
1586    if (err)
1587        return err;
1588
1589    /* Step 1 */
1590    sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
1591                   sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
1592                   0, 0, NULL);
1593    if (!sc)
1594        return -ENOMEM;
1595
1596    for (i = conf->max_nr_stripes; i; i--) {
1597        nsh = kmem_cache_zalloc(sc, GFP_KERNEL);
1598        if (!nsh)
1599            break;
1600
1601        nsh->raid_conf = conf;
1602        spin_lock_init(&nsh->stripe_lock);
1603
1604        list_add(&nsh->lru, &newstripes);
1605    }
1606    if (i) {
1607        /* didn't get enough, give up */
1608        while (!list_empty(&newstripes)) {
1609            nsh = list_entry(newstripes.next, struct stripe_head, lru);
1610            list_del(&nsh->lru);
1611            kmem_cache_free(sc, nsh);
1612        }
1613        kmem_cache_destroy(sc);
1614        return -ENOMEM;
1615    }
1616    /* Step 2 - Must use GFP_NOIO now.
1617     * OK, we have enough stripes, start collecting inactive
1618     * stripes and copying them over
1619     */
1620    list_for_each_entry(nsh, &newstripes, lru) {
1621        spin_lock_irq(&conf->device_lock);
1622        wait_event_lock_irq(conf->wait_for_stripe,
1623                    !list_empty(&conf->inactive_list),
1624                    conf->device_lock);
1625        osh = get_free_stripe(conf);
1626        spin_unlock_irq(&conf->device_lock);
1627        atomic_set(&nsh->count, 1);
1628        for(i=0; i<conf->pool_size; i++)
1629            nsh->dev[i].page = osh->dev[i].page;
1630        for( ; i<newsize; i++)
1631            nsh->dev[i].page = NULL;
1632        kmem_cache_free(conf->slab_cache, osh);
1633    }
1634    kmem_cache_destroy(conf->slab_cache);
1635
1636    /* Step 3.
1637     * At this point, we are holding all the stripes so the array
1638     * is completely stalled, so now is a good time to resize
1639     * conf->disks and the scribble region
1640     */
1641    ndisks = kzalloc(newsize * sizeof(struct disk_info), GFP_NOIO);
1642    if (ndisks) {
1643        for (i=0; i<conf->raid_disks; i++)
1644            ndisks[i] = conf->disks[i];
1645        kfree(conf->disks);
1646        conf->disks = ndisks;
1647    } else
1648        err = -ENOMEM;
1649
1650    get_online_cpus();
1651    conf->scribble_len = scribble_len(newsize);
1652    for_each_present_cpu(cpu) {
1653        struct raid5_percpu *percpu;
1654        void *scribble;
1655
1656        percpu = per_cpu_ptr(conf->percpu, cpu);
1657        scribble = kmalloc(conf->scribble_len, GFP_NOIO);
1658
1659        if (scribble) {
1660            kfree(percpu->scribble);
1661            percpu->scribble = scribble;
1662        } else {
1663            err = -ENOMEM;
1664            break;
1665        }
1666    }
1667    put_online_cpus();
1668
1669    /* Step 4, return new stripes to service */
1670    while(!list_empty(&newstripes)) {
1671        nsh = list_entry(newstripes.next, struct stripe_head, lru);
1672        list_del_init(&nsh->lru);
1673
1674        for (i=conf->raid_disks; i < newsize; i++)
1675            if (nsh->dev[i].page == NULL) {
1676                struct page *p = alloc_page(GFP_NOIO);
1677                nsh->dev[i].page = p;
1678                if (!p)
1679                    err = -ENOMEM;
1680            }
1681        release_stripe(nsh);
1682    }
1683    /* critical section pass, GFP_NOIO no longer needed */
1684
1685    conf->slab_cache = sc;
1686    conf->active_name = 1-conf->active_name;
1687    conf->pool_size = newsize;
1688    return err;
1689}
1690
1691static int drop_one_stripe(struct r5conf *conf)
1692{
1693    struct stripe_head *sh;
1694
1695    spin_lock_irq(&conf->device_lock);
1696    sh = get_free_stripe(conf);
1697    spin_unlock_irq(&conf->device_lock);
1698    if (!sh)
1699        return 0;
1700    BUG_ON(atomic_read(&sh->count));
1701    shrink_buffers(sh);
1702    kmem_cache_free(conf->slab_cache, sh);
1703    atomic_dec(&conf->active_stripes);
1704    return 1;
1705}
1706
1707static void shrink_stripes(struct r5conf *conf)
1708{
1709    while (drop_one_stripe(conf))
1710        ;
1711
1712    if (conf->slab_cache)
1713        kmem_cache_destroy(conf->slab_cache);
1714    conf->slab_cache = NULL;
1715}
1716
1717static void raid5_end_read_request(struct bio * bi, int error)
1718{
1719    struct stripe_head *sh = bi->bi_private;
1720    struct r5conf *conf = sh->raid_conf;
1721    int disks = sh->disks, i;
1722    int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
1723    char b[BDEVNAME_SIZE];
1724    struct md_rdev *rdev = NULL;
1725    sector_t s;
1726
1727    for (i=0 ; i<disks; i++)
1728        if (bi == &sh->dev[i].req)
1729            break;
1730
1731    pr_debug("end_read_request %llu/%d, count: %d, uptodate %d.\n",
1732        (unsigned long long)sh->sector, i, atomic_read(&sh->count),
1733        uptodate);
1734    if (i == disks) {
1735        BUG();
1736        return;
1737    }
1738    if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
1739        /* If replacement finished while this request was outstanding,
1740         * 'replacement' might be NULL already.
1741         * In that case it moved down to 'rdev'.
1742         * rdev is not removed until all requests are finished.
1743         */
1744        rdev = conf->disks[i].replacement;
1745    if (!rdev)
1746        rdev = conf->disks[i].rdev;
1747
1748    if (use_new_offset(conf, sh))
1749        s = sh->sector + rdev->new_data_offset;
1750    else
1751        s = sh->sector + rdev->data_offset;
1752    if (uptodate) {
1753        set_bit(R5_UPTODATE, &sh->dev[i].flags);
1754        if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
1755            /* Note that this cannot happen on a
1756             * replacement device. We just fail those on
1757             * any error
1758             */
1759            printk_ratelimited(
1760                KERN_INFO
1761                "md/raid:%s: read error corrected"
1762                " (%lu sectors at %llu on %s)\n",
1763                mdname(conf->mddev), STRIPE_SECTORS,
1764                (unsigned long long)s,
1765                bdevname(rdev->bdev, b));
1766            atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
1767            clear_bit(R5_ReadError, &sh->dev[i].flags);
1768            clear_bit(R5_ReWrite, &sh->dev[i].flags);
1769        } else if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
1770            clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
1771
1772        if (atomic_read(&rdev->read_errors))
1773            atomic_set(&rdev->read_errors, 0);
1774    } else {
1775        const char *bdn = bdevname(rdev->bdev, b);
1776        int retry = 0;
1777        int set_bad = 0;
1778
1779        clear_bit(R5_UPTODATE, &sh->dev[i].flags);
1780        atomic_inc(&rdev->read_errors);
1781        if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
1782            printk_ratelimited(
1783                KERN_WARNING
1784                "md/raid:%s: read error on replacement device "
1785                "(sector %llu on %s).\n",
1786                mdname(conf->mddev),
1787                (unsigned long long)s,
1788                bdn);
1789        else if (conf->mddev->degraded >= conf->max_degraded) {
1790            set_bad = 1;
1791            printk_ratelimited(
1792                KERN_WARNING
1793                "md/raid:%s: read error not correctable "
1794                "(sector %llu on %s).\n",
1795                mdname(conf->mddev),
1796                (unsigned long long)s,
1797                bdn);
1798        } else if (test_bit(R5_ReWrite, &sh->dev[i].flags)) {
1799            /* Oh, no!!! */
1800            set_bad = 1;
1801            printk_ratelimited(
1802                KERN_WARNING
1803                "md/raid:%s: read error NOT corrected!! "
1804                "(sector %llu on %s).\n",
1805                mdname(conf->mddev),
1806                (unsigned long long)s,
1807                bdn);
1808        } else if (atomic_read(&rdev->read_errors)
1809             > conf->max_nr_stripes)
1810            printk(KERN_WARNING
1811                   "md/raid:%s: Too many read errors, failing device %s.\n",
1812                   mdname(conf->mddev), bdn);
1813        else
1814            retry = 1;
1815        if (retry)
1816            if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags)) {
1817                set_bit(R5_ReadError, &sh->dev[i].flags);
1818                clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
1819            } else
1820                set_bit(R5_ReadNoMerge, &sh->dev[i].flags);
1821        else {
1822            clear_bit(R5_ReadError, &sh->dev[i].flags);
1823            clear_bit(R5_ReWrite, &sh->dev[i].flags);
1824            if (!(set_bad
1825                  && test_bit(In_sync, &rdev->flags)
1826                  && rdev_set_badblocks(
1827                      rdev, sh->sector, STRIPE_SECTORS, 0)))
1828                md_error(conf->mddev, rdev);
1829        }
1830    }
1831    rdev_dec_pending(rdev, conf->mddev);
1832    clear_bit(R5_LOCKED, &sh->dev[i].flags);
1833    set_bit(STRIPE_HANDLE, &sh->state);
1834    release_stripe(sh);
1835}
1836
1837static void raid5_end_write_request(struct bio *bi, int error)
1838{
1839    struct stripe_head *sh = bi->bi_private;
1840    struct r5conf *conf = sh->raid_conf;
1841    int disks = sh->disks, i;
1842    struct md_rdev *uninitialized_var(rdev);
1843    int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
1844    sector_t first_bad;
1845    int bad_sectors;
1846    int replacement = 0;
1847
1848    for (i = 0 ; i < disks; i++) {
1849        if (bi == &sh->dev[i].req) {
1850            rdev = conf->disks[i].rdev;
1851            break;
1852        }
1853        if (bi == &sh->dev[i].rreq) {
1854            rdev = conf->disks[i].replacement;
1855            if (rdev)
1856                replacement = 1;
1857            else
1858                /* rdev was removed and 'replacement'
1859                 * replaced it. rdev is not removed
1860                 * until all requests are finished.
1861                 */
1862                rdev = conf->disks[i].rdev;
1863            break;
1864        }
1865    }
1866    pr_debug("end_write_request %llu/%d, count %d, uptodate: %d.\n",
1867        (unsigned long long)sh->sector, i, atomic_read(&sh->count),
1868        uptodate);
1869    if (i == disks) {
1870        BUG();
1871        return;
1872    }
1873
1874    if (replacement) {
1875        if (!uptodate)
1876            md_error(conf->mddev, rdev);
1877        else if (is_badblock(rdev, sh->sector,
1878                     STRIPE_SECTORS,
1879                     &first_bad, &bad_sectors))
1880            set_bit(R5_MadeGoodRepl, &sh->dev[i].flags);
1881    } else {
1882        if (!uptodate) {
1883            set_bit(WriteErrorSeen, &rdev->flags);
1884            set_bit(R5_WriteError, &sh->dev[i].flags);
1885            if (!test_and_set_bit(WantReplacement, &rdev->flags))
1886                set_bit(MD_RECOVERY_NEEDED,
1887                    &rdev->mddev->recovery);
1888        } else if (is_badblock(rdev, sh->sector,
1889                       STRIPE_SECTORS,
1890                       &first_bad, &bad_sectors))
1891            set_bit(R5_MadeGood, &sh->dev[i].flags);
1892    }
1893    rdev_dec_pending(rdev, conf->mddev);
1894
1895    if (!test_and_clear_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags))
1896        clear_bit(R5_LOCKED, &sh->dev[i].flags);
1897    set_bit(STRIPE_HANDLE, &sh->state);
1898    release_stripe(sh);
1899}
1900
1901static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous);
1902    
1903static void raid5_build_block(struct stripe_head *sh, int i, int previous)
1904{
1905    struct r5dev *dev = &sh->dev[i];
1906
1907    bio_init(&dev->req);
1908    dev->req.bi_io_vec = &dev->vec;
1909    dev->req.bi_vcnt++;
1910    dev->req.bi_max_vecs++;
1911    dev->req.bi_private = sh;
1912    dev->vec.bv_page = dev->page;
1913
1914    bio_init(&dev->rreq);
1915    dev->rreq.bi_io_vec = &dev->rvec;
1916    dev->rreq.bi_vcnt++;
1917    dev->rreq.bi_max_vecs++;
1918    dev->rreq.bi_private = sh;
1919    dev->rvec.bv_page = dev->page;
1920
1921    dev->flags = 0;
1922    dev->sector = compute_blocknr(sh, i, previous);
1923}
1924
1925static void error(struct mddev *mddev, struct md_rdev *rdev)
1926{
1927    char b[BDEVNAME_SIZE];
1928    struct r5conf *conf = mddev->private;
1929    unsigned long flags;
1930    pr_debug("raid456: error called\n");
1931
1932    spin_lock_irqsave(&conf->device_lock, flags);
1933    clear_bit(In_sync, &rdev->flags);
1934    mddev->degraded = calc_degraded(conf);
1935    spin_unlock_irqrestore(&conf->device_lock, flags);
1936    set_bit(MD_RECOVERY_INTR, &mddev->recovery);
1937
1938    set_bit(Blocked, &rdev->flags);
1939    set_bit(Faulty, &rdev->flags);
1940    set_bit(MD_CHANGE_DEVS, &mddev->flags);
1941    printk(KERN_ALERT
1942           "md/raid:%s: Disk failure on %s, disabling device.\n"
1943           "md/raid:%s: Operation continuing on %d devices.\n",
1944           mdname(mddev),
1945           bdevname(rdev->bdev, b),
1946           mdname(mddev),
1947           conf->raid_disks - mddev->degraded);
1948}
1949
1950/*
1951 * Input: a 'big' sector number,
1952 * Output: index of the data and parity disk, and the sector # in them.
1953 */
1954static sector_t raid5_compute_sector(struct r5conf *conf, sector_t r_sector,
1955                     int previous, int *dd_idx,
1956                     struct stripe_head *sh)
1957{
1958    sector_t stripe, stripe2;
1959    sector_t chunk_number;
1960    unsigned int chunk_offset;
1961    int pd_idx, qd_idx;
1962    int ddf_layout = 0;
1963    sector_t new_sector;
1964    int algorithm = previous ? conf->prev_algo
1965                 : conf->algorithm;
1966    int sectors_per_chunk = previous ? conf->prev_chunk_sectors
1967                     : conf->chunk_sectors;
1968    int raid_disks = previous ? conf->previous_raid_disks
1969                  : conf->raid_disks;
1970    int data_disks = raid_disks - conf->max_degraded;
1971
1972    /* First compute the information on this sector */
1973
1974    /*
1975     * Compute the chunk number and the sector offset inside the chunk
1976     */
1977    chunk_offset = sector_div(r_sector, sectors_per_chunk);
1978    chunk_number = r_sector;
1979
1980    /*
1981     * Compute the stripe number
1982     */
1983    stripe = chunk_number;
1984    *dd_idx = sector_div(stripe, data_disks);
1985    stripe2 = stripe;
1986    /*
1987     * Select the parity disk based on the user selected algorithm.
1988     */
1989    pd_idx = qd_idx = -1;
1990    switch(conf->level) {
1991    case 4:
1992        pd_idx = data_disks;
1993        break;
1994    case 5:
1995        switch (algorithm) {
1996        case ALGORITHM_LEFT_ASYMMETRIC:
1997            pd_idx = data_disks - sector_div(stripe2, raid_disks);
1998            if (*dd_idx >= pd_idx)
1999                (*dd_idx)++;
2000            break;
2001        case ALGORITHM_RIGHT_ASYMMETRIC:
2002            pd_idx = sector_div(stripe2, raid_disks);
2003            if (*dd_idx >= pd_idx)
2004                (*dd_idx)++;
2005            break;
2006        case ALGORITHM_LEFT_SYMMETRIC:
2007            pd_idx = data_disks - sector_div(stripe2, raid_disks);
2008            *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2009            break;
2010        case ALGORITHM_RIGHT_SYMMETRIC:
2011            pd_idx = sector_div(stripe2, raid_disks);
2012            *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2013            break;
2014        case ALGORITHM_PARITY_0:
2015            pd_idx = 0;
2016            (*dd_idx)++;
2017            break;
2018        case ALGORITHM_PARITY_N:
2019            pd_idx = data_disks;
2020            break;
2021        default:
2022            BUG();
2023        }
2024        break;
2025    case 6:
2026
2027        switch (algorithm) {
2028        case ALGORITHM_LEFT_ASYMMETRIC:
2029            pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2030            qd_idx = pd_idx + 1;
2031            if (pd_idx == raid_disks-1) {
2032                (*dd_idx)++; /* Q D D D P */
2033                qd_idx = 0;
2034            } else if (*dd_idx >= pd_idx)
2035                (*dd_idx) += 2; /* D D P Q D */
2036            break;
2037        case ALGORITHM_RIGHT_ASYMMETRIC:
2038            pd_idx = sector_div(stripe2, raid_disks);
2039            qd_idx = pd_idx + 1;
2040            if (pd_idx == raid_disks-1) {
2041                (*dd_idx)++; /* Q D D D P */
2042                qd_idx = 0;
2043            } else if (*dd_idx >= pd_idx)
2044                (*dd_idx) += 2; /* D D P Q D */
2045            break;
2046        case ALGORITHM_LEFT_SYMMETRIC:
2047            pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2048            qd_idx = (pd_idx + 1) % raid_disks;
2049            *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2050            break;
2051        case ALGORITHM_RIGHT_SYMMETRIC:
2052            pd_idx = sector_div(stripe2, raid_disks);
2053            qd_idx = (pd_idx + 1) % raid_disks;
2054            *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2055            break;
2056
2057        case ALGORITHM_PARITY_0:
2058            pd_idx = 0;
2059            qd_idx = 1;
2060            (*dd_idx) += 2;
2061            break;
2062        case ALGORITHM_PARITY_N:
2063            pd_idx = data_disks;
2064            qd_idx = data_disks + 1;
2065            break;
2066
2067        case ALGORITHM_ROTATING_ZERO_RESTART:
2068            /* Exactly the same as RIGHT_ASYMMETRIC, but or
2069             * of blocks for computing Q is different.
2070             */
2071            pd_idx = sector_div(stripe2, raid_disks);
2072            qd_idx = pd_idx + 1;
2073            if (pd_idx == raid_disks-1) {
2074                (*dd_idx)++; /* Q D D D P */
2075                qd_idx = 0;
2076            } else if (*dd_idx >= pd_idx)
2077                (*dd_idx) += 2; /* D D P Q D */
2078            ddf_layout = 1;
2079            break;
2080
2081        case ALGORITHM_ROTATING_N_RESTART:
2082            /* Same a left_asymmetric, by first stripe is
2083             * D D D P Q rather than
2084             * Q D D D P
2085             */
2086            stripe2 += 1;
2087            pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2088            qd_idx = pd_idx + 1;
2089            if (pd_idx == raid_disks-1) {
2090                (*dd_idx)++; /* Q D D D P */
2091                qd_idx = 0;
2092            } else if (*dd_idx >= pd_idx)
2093                (*dd_idx) += 2; /* D D P Q D */
2094            ddf_layout = 1;
2095            break;
2096
2097        case ALGORITHM_ROTATING_N_CONTINUE:
2098            /* Same as left_symmetric but Q is before P */
2099            pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2100            qd_idx = (pd_idx + raid_disks - 1) % raid_disks;
2101            *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2102            ddf_layout = 1;
2103            break;
2104
2105        case ALGORITHM_LEFT_ASYMMETRIC_6:
2106            /* RAID5 left_asymmetric, with Q on last device */
2107            pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2108            if (*dd_idx >= pd_idx)
2109                (*dd_idx)++;
2110            qd_idx = raid_disks - 1;
2111            break;
2112
2113        case ALGORITHM_RIGHT_ASYMMETRIC_6:
2114            pd_idx = sector_div(stripe2, raid_disks-1);
2115            if (*dd_idx >= pd_idx)
2116                (*dd_idx)++;
2117            qd_idx = raid_disks - 1;
2118            break;
2119
2120        case ALGORITHM_LEFT_SYMMETRIC_6:
2121            pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2122            *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2123            qd_idx = raid_disks - 1;
2124            break;
2125
2126        case ALGORITHM_RIGHT_SYMMETRIC_6:
2127            pd_idx = sector_div(stripe2, raid_disks-1);
2128            *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2129            qd_idx = raid_disks - 1;
2130            break;
2131
2132        case ALGORITHM_PARITY_0_6:
2133            pd_idx = 0;
2134            (*dd_idx)++;
2135            qd_idx = raid_disks - 1;
2136            break;
2137
2138        default:
2139            BUG();
2140        }
2141        break;
2142    }
2143
2144    if (sh) {
2145        sh->pd_idx = pd_idx;
2146        sh->qd_idx = qd_idx;
2147        sh->ddf_layout = ddf_layout;
2148    }
2149    /*
2150     * Finally, compute the new sector number
2151     */
2152    new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
2153    return new_sector;
2154}
2155
2156
2157static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous)
2158{
2159    struct r5conf *conf = sh->raid_conf;
2160    int raid_disks = sh->disks;
2161    int data_disks = raid_disks - conf->max_degraded;
2162    sector_t new_sector = sh->sector, check;
2163    int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2164                     : conf->chunk_sectors;
2165    int algorithm = previous ? conf->prev_algo
2166                 : conf->algorithm;
2167    sector_t stripe;
2168    int chunk_offset;
2169    sector_t chunk_number;
2170    int dummy1, dd_idx = i;
2171    sector_t r_sector;
2172    struct stripe_head sh2;
2173
2174
2175    chunk_offset = sector_div(new_sector, sectors_per_chunk);
2176    stripe = new_sector;
2177
2178    if (i == sh->pd_idx)
2179        return 0;
2180    switch(conf->level) {
2181    case 4: break;
2182    case 5:
2183        switch (algorithm) {
2184        case ALGORITHM_LEFT_ASYMMETRIC:
2185        case ALGORITHM_RIGHT_ASYMMETRIC:
2186            if (i > sh->pd_idx)
2187                i--;
2188            break;
2189        case ALGORITHM_LEFT_SYMMETRIC:
2190        case ALGORITHM_RIGHT_SYMMETRIC:
2191            if (i < sh->pd_idx)
2192                i += raid_disks;
2193            i -= (sh->pd_idx + 1);
2194            break;
2195        case ALGORITHM_PARITY_0:
2196            i -= 1;
2197            break;
2198        case ALGORITHM_PARITY_N:
2199            break;
2200        default:
2201            BUG();
2202        }
2203        break;
2204    case 6:
2205        if (i == sh->qd_idx)
2206            return 0; /* It is the Q disk */
2207        switch (algorithm) {
2208        case ALGORITHM_LEFT_ASYMMETRIC:
2209        case ALGORITHM_RIGHT_ASYMMETRIC:
2210        case ALGORITHM_ROTATING_ZERO_RESTART:
2211        case ALGORITHM_ROTATING_N_RESTART:
2212            if (sh->pd_idx == raid_disks-1)
2213                i--; /* Q D D D P */
2214            else if (i > sh->pd_idx)
2215                i -= 2; /* D D P Q D */
2216            break;
2217        case ALGORITHM_LEFT_SYMMETRIC:
2218        case ALGORITHM_RIGHT_SYMMETRIC:
2219            if (sh->pd_idx == raid_disks-1)
2220                i--; /* Q D D D P */
2221            else {
2222                /* D D P Q D */
2223                if (i < sh->pd_idx)
2224                    i += raid_disks;
2225                i -= (sh->pd_idx + 2);
2226            }
2227            break;
2228        case ALGORITHM_PARITY_0:
2229            i -= 2;
2230            break;
2231        case ALGORITHM_PARITY_N:
2232            break;
2233        case ALGORITHM_ROTATING_N_CONTINUE:
2234            /* Like left_symmetric, but P is before Q */
2235            if (sh->pd_idx == 0)
2236                i--; /* P D D D Q */
2237            else {
2238                /* D D Q P D */
2239                if (i < sh->pd_idx)
2240                    i += raid_disks;
2241                i -= (sh->pd_idx + 1);
2242            }
2243            break;
2244        case ALGORITHM_LEFT_ASYMMETRIC_6:
2245        case ALGORITHM_RIGHT_ASYMMETRIC_6:
2246            if (i > sh->pd_idx)
2247                i--;
2248            break;
2249        case ALGORITHM_LEFT_SYMMETRIC_6:
2250        case ALGORITHM_RIGHT_SYMMETRIC_6:
2251            if (i < sh->pd_idx)
2252                i += data_disks + 1;
2253            i -= (sh->pd_idx + 1);
2254            break;
2255        case ALGORITHM_PARITY_0_6:
2256            i -= 1;
2257            break;
2258        default:
2259            BUG();
2260        }
2261        break;
2262    }
2263
2264    chunk_number = stripe * data_disks + i;
2265    r_sector = chunk_number * sectors_per_chunk + chunk_offset;
2266
2267    check = raid5_compute_sector(conf, r_sector,
2268                     previous, &dummy1, &sh2);
2269    if (check != sh->sector || dummy1 != dd_idx || sh2.pd_idx != sh->pd_idx
2270        || sh2.qd_idx != sh->qd_idx) {
2271        printk(KERN_ERR "md/raid:%s: compute_blocknr: map not correct\n",
2272               mdname(conf->mddev));
2273        return 0;
2274    }
2275    return r_sector;
2276}
2277
2278
2279static void
2280schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s,
2281             int rcw, int expand)
2282{
2283    int i, pd_idx = sh->pd_idx, disks = sh->disks;
2284    struct r5conf *conf = sh->raid_conf;
2285    int level = conf->level;
2286
2287    if (rcw) {
2288
2289        for (i = disks; i--; ) {
2290            struct r5dev *dev = &sh->dev[i];
2291
2292            if (dev->towrite) {
2293                set_bit(R5_LOCKED, &dev->flags);
2294                set_bit(R5_Wantdrain, &dev->flags);
2295                if (!expand)
2296                    clear_bit(R5_UPTODATE, &dev->flags);
2297                s->locked++;
2298            }
2299        }
2300        /* if we are not expanding this is a proper write request, and
2301         * there will be bios with new data to be drained into the
2302         * stripe cache
2303         */
2304        if (!expand) {
2305            if (!s->locked)
2306                /* False alarm, nothing to do */
2307                return;
2308            sh->reconstruct_state = reconstruct_state_drain_run;
2309            set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2310        } else
2311            sh->reconstruct_state = reconstruct_state_run;
2312
2313        set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2314
2315        if (s->locked + conf->max_degraded == disks)
2316            if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
2317                atomic_inc(&conf->pending_full_writes);
2318    } else {
2319        BUG_ON(level == 6);
2320        BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
2321            test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
2322
2323        for (i = disks; i--; ) {
2324            struct r5dev *dev = &sh->dev[i];
2325            if (i == pd_idx)
2326                continue;
2327
2328            if (dev->towrite &&
2329                (test_bit(R5_UPTODATE, &dev->flags) ||
2330                 test_bit(R5_Wantcompute, &dev->flags))) {
2331                set_bit(R5_Wantdrain, &dev->flags);
2332                set_bit(R5_LOCKED, &dev->flags);
2333                clear_bit(R5_UPTODATE, &dev->flags);
2334                s->locked++;
2335            }
2336        }
2337        if (!s->locked)
2338            /* False alarm - nothing to do */
2339            return;
2340        sh->reconstruct_state = reconstruct_state_prexor_drain_run;
2341        set_bit(STRIPE_OP_PREXOR, &s->ops_request);
2342        set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2343        set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2344    }
2345
2346    /* keep the parity disk(s) locked while asynchronous operations
2347     * are in flight
2348     */
2349    set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
2350    clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
2351    s->locked++;
2352
2353    if (level == 6) {
2354        int qd_idx = sh->qd_idx;
2355        struct r5dev *dev = &sh->dev[qd_idx];
2356
2357        set_bit(R5_LOCKED, &dev->flags);
2358        clear_bit(R5_UPTODATE, &dev->flags);
2359        s->locked++;
2360    }
2361
2362    pr_debug("%s: stripe %llu locked: %d ops_request: %lx\n",
2363        __func__, (unsigned long long)sh->sector,
2364        s->locked, s->ops_request);
2365}
2366
2367/*
2368 * Each stripe/dev can have one or more bion attached.
2369 * toread/towrite point to the first in a chain.
2370 * The bi_next chain must be in order.
2371 */
2372static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, int forwrite)
2373{
2374    struct bio **bip;
2375    struct r5conf *conf = sh->raid_conf;
2376    int firstwrite=0;
2377
2378    pr_debug("adding bi b#%llu to stripe s#%llu\n",
2379        (unsigned long long)bi->bi_sector,
2380        (unsigned long long)sh->sector);
2381
2382    /*
2383     * If several bio share a stripe. The bio bi_phys_segments acts as a
2384     * reference count to avoid race. The reference count should already be
2385     * increased before this function is called (for example, in
2386     * make_request()), so other bio sharing this stripe will not free the
2387     * stripe. If a stripe is owned by one stripe, the stripe lock will
2388     * protect it.
2389     */
2390    spin_lock_irq(&sh->stripe_lock);
2391    if (forwrite) {
2392        bip = &sh->dev[dd_idx].towrite;
2393        if (*bip == NULL)
2394            firstwrite = 1;
2395    } else
2396        bip = &sh->dev[dd_idx].toread;
2397    while (*bip && (*bip)->bi_sector < bi->bi_sector) {
2398        if ((*bip)->bi_sector + ((*bip)->bi_size >> 9) > bi->bi_sector)
2399            goto overlap;
2400        bip = & (*bip)->bi_next;
2401    }
2402    if (*bip && (*bip)->bi_sector < bi->bi_sector + ((bi->bi_size)>>9))
2403        goto overlap;
2404
2405    BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
2406    if (*bip)
2407        bi->bi_next = *bip;
2408    *bip = bi;
2409    raid5_inc_bi_active_stripes(bi);
2410
2411    if (forwrite) {
2412        /* check if page is covered */
2413        sector_t sector = sh->dev[dd_idx].sector;
2414        for (bi=sh->dev[dd_idx].towrite;
2415             sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
2416                 bi && bi->bi_sector <= sector;
2417             bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
2418            if (bi->bi_sector + (bi->bi_size>>9) >= sector)
2419                sector = bi->bi_sector + (bi->bi_size>>9);
2420        }
2421        if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
2422            set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags);
2423    }
2424
2425    pr_debug("added bi b#%llu to stripe s#%llu, disk %d.\n",
2426        (unsigned long long)(*bip)->bi_sector,
2427        (unsigned long long)sh->sector, dd_idx);
2428    spin_unlock_irq(&sh->stripe_lock);
2429
2430    if (conf->mddev->bitmap && firstwrite) {
2431        bitmap_startwrite(conf->mddev->bitmap, sh->sector,
2432                  STRIPE_SECTORS, 0);
2433        sh->bm_seq = conf->seq_flush+1;
2434        set_bit(STRIPE_BIT_DELAY, &sh->state);
2435    }
2436    return 1;
2437
2438 overlap:
2439    set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
2440    spin_unlock_irq(&sh->stripe_lock);
2441    return 0;
2442}
2443
2444static void end_reshape(struct r5conf *conf);
2445
2446static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
2447                struct stripe_head *sh)
2448{
2449    int sectors_per_chunk =
2450        previous ? conf->prev_chunk_sectors : conf->chunk_sectors;
2451    int dd_idx;
2452    int chunk_offset = sector_div(stripe, sectors_per_chunk);
2453    int disks = previous ? conf->previous_raid_disks : conf->raid_disks;
2454
2455    raid5_compute_sector(conf,
2456                 stripe * (disks - conf->max_degraded)
2457                 *sectors_per_chunk + chunk_offset,
2458                 previous,
2459                 &dd_idx, sh);
2460}
2461
2462static void
2463handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
2464                struct stripe_head_state *s, int disks,
2465                struct bio **return_bi)
2466{
2467    int i;
2468    for (i = disks; i--; ) {
2469        struct bio *bi;
2470        int bitmap_end = 0;
2471
2472        if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
2473            struct md_rdev *rdev;
2474            rcu_read_lock();
2475            rdev = rcu_dereference(conf->disks[i].rdev);
2476            if (rdev && test_bit(In_sync, &rdev->flags))
2477                atomic_inc(&rdev->nr_pending);
2478            else
2479                rdev = NULL;
2480            rcu_read_unlock();
2481            if (rdev) {
2482                if (!rdev_set_badblocks(
2483                        rdev,
2484                        sh->sector,
2485                        STRIPE_SECTORS, 0))
2486                    md_error(conf->mddev, rdev);
2487                rdev_dec_pending(rdev, conf->mddev);
2488            }
2489        }
2490        spin_lock_irq(&sh->stripe_lock);
2491        /* fail all writes first */
2492        bi = sh->dev[i].towrite;
2493        sh->dev[i].towrite = NULL;
2494        spin_unlock_irq(&sh->stripe_lock);
2495        if (bi)
2496            bitmap_end = 1;
2497
2498        if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
2499            wake_up(&conf->wait_for_overlap);
2500
2501        while (bi && bi->bi_sector <
2502            sh->dev[i].sector + STRIPE_SECTORS) {
2503            struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
2504            clear_bit(BIO_UPTODATE, &bi->bi_flags);
2505            if (!raid5_dec_bi_active_stripes(bi)) {
2506                md_write_end(conf->mddev);
2507                bi->bi_next = *return_bi;
2508                *return_bi = bi;
2509            }
2510            bi = nextbi;
2511        }
2512        if (bitmap_end)
2513            bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2514                STRIPE_SECTORS, 0, 0);
2515        bitmap_end = 0;
2516        /* and fail all 'written' */
2517        bi = sh->dev[i].written;
2518        sh->dev[i].written = NULL;
2519        if (bi) bitmap_end = 1;
2520        while (bi && bi->bi_sector <
2521               sh->dev[i].sector + STRIPE_SECTORS) {
2522            struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
2523            clear_bit(BIO_UPTODATE, &bi->bi_flags);
2524            if (!raid5_dec_bi_active_stripes(bi)) {
2525                md_write_end(conf->mddev);
2526                bi->bi_next = *return_bi;
2527                *return_bi = bi;
2528            }
2529            bi = bi2;
2530        }
2531
2532        /* fail any reads if this device is non-operational and
2533         * the data has not reached the cache yet.
2534         */
2535        if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&
2536            (!test_bit(R5_Insync, &sh->dev[i].flags) ||
2537              test_bit(R5_ReadError, &sh->dev[i].flags))) {
2538            spin_lock_irq(&sh->stripe_lock);
2539            bi = sh->dev[i].toread;
2540            sh->dev[i].toread = NULL;
2541            spin_unlock_irq(&sh->stripe_lock);
2542            if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
2543                wake_up(&conf->wait_for_overlap);
2544            while (bi && bi->bi_sector <
2545                   sh->dev[i].sector + STRIPE_SECTORS) {
2546                struct bio *nextbi =
2547                    r5_next_bio(bi, sh->dev[i].sector);
2548                clear_bit(BIO_UPTODATE, &bi->bi_flags);
2549                if (!raid5_dec_bi_active_stripes(bi)) {
2550                    bi->bi_next = *return_bi;
2551                    *return_bi = bi;
2552                }
2553                bi = nextbi;
2554            }
2555        }
2556        if (bitmap_end)
2557            bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2558                    STRIPE_SECTORS, 0, 0);
2559        /* If we were in the middle of a write the parity block might
2560         * still be locked - so just clear all R5_LOCKED flags
2561         */
2562        clear_bit(R5_LOCKED, &sh->dev[i].flags);
2563    }
2564
2565    if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
2566        if (atomic_dec_and_test(&conf->pending_full_writes))
2567            md_wakeup_thread(conf->mddev->thread);
2568}
2569
2570static void
2571handle_failed_sync(struct r5conf *conf, struct stripe_head *sh,
2572           struct stripe_head_state *s)
2573{
2574    int abort = 0;
2575    int i;
2576
2577    clear_bit(STRIPE_SYNCING, &sh->state);
2578    if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
2579        wake_up(&conf->wait_for_overlap);
2580    s->syncing = 0;
2581    s->replacing = 0;
2582    /* There is nothing more to do for sync/check/repair.
2583     * Don't even need to abort as that is handled elsewhere
2584     * if needed, and not always wanted e.g. if there is a known
2585     * bad block here.
2586     * For recover/replace we need to record a bad block on all
2587     * non-sync devices, or abort the recovery
2588     */
2589    if (test_bit(MD_RECOVERY_RECOVER, &conf->mddev->recovery)) {
2590        /* During recovery devices cannot be removed, so
2591         * locking and refcounting of rdevs is not needed
2592         */
2593        for (i = 0; i < conf->raid_disks; i++) {
2594            struct md_rdev *rdev = conf->disks[i].rdev;
2595            if (rdev
2596                && !test_bit(Faulty, &rdev->flags)
2597                && !test_bit(In_sync, &rdev->flags)
2598                && !rdev_set_badblocks(rdev, sh->sector,
2599                           STRIPE_SECTORS, 0))
2600                abort = 1;
2601            rdev = conf->disks[i].replacement;
2602            if (rdev
2603                && !test_bit(Faulty, &rdev->flags)
2604                && !test_bit(In_sync, &rdev->flags)
2605                && !rdev_set_badblocks(rdev, sh->sector,
2606                           STRIPE_SECTORS, 0))
2607                abort = 1;
2608        }
2609        if (abort)
2610            conf->recovery_disabled =
2611                conf->mddev->recovery_disabled;
2612    }
2613    md_done_sync(conf->mddev, STRIPE_SECTORS, !abort);
2614}
2615
2616static int want_replace(struct stripe_head *sh, int disk_idx)
2617{
2618    struct md_rdev *rdev;
2619    int rv = 0;
2620    /* Doing recovery so rcu locking not required */
2621    rdev = sh->raid_conf->disks[disk_idx].replacement;
2622    if (rdev
2623        && !test_bit(Faulty, &rdev->flags)
2624        && !test_bit(In_sync, &rdev->flags)
2625        && (rdev->recovery_offset <= sh->sector
2626        || rdev->mddev->recovery_cp <= sh->sector))
2627        rv = 1;
2628
2629    return rv;
2630}
2631
2632/* fetch_block - checks the given member device to see if its data needs
2633 * to be read or computed to satisfy a request.
2634 *
2635 * Returns 1 when no more member devices need to be checked, otherwise returns
2636 * 0 to tell the loop in handle_stripe_fill to continue
2637 */
2638static int fetch_block(struct stripe_head *sh, struct stripe_head_state *s,
2639               int disk_idx, int disks)
2640{
2641    struct r5dev *dev = &sh->dev[disk_idx];
2642    struct r5dev *fdev[2] = { &sh->dev[s->failed_num[0]],
2643                  &sh->dev[s->failed_num[1]] };
2644
2645    /* is the data in this block needed, and can we get it? */
2646    if (!test_bit(R5_LOCKED, &dev->flags) &&
2647        !test_bit(R5_UPTODATE, &dev->flags) &&
2648        (dev->toread ||
2649         (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
2650         s->syncing || s->expanding ||
2651         (s->replacing && want_replace(sh, disk_idx)) ||
2652         (s->failed >= 1 && fdev[0]->toread) ||
2653         (s->failed >= 2 && fdev[1]->toread) ||
2654         (sh->raid_conf->level <= 5 && s->failed && fdev[0]->towrite &&
2655          !test_bit(R5_OVERWRITE, &fdev[0]->flags)) ||
2656         (sh->raid_conf->level == 6 && s->failed && s->to_write))) {
2657        /* we would like to get this block, possibly by computing it,
2658         * otherwise read it if the backing disk is insync
2659         */
2660        BUG_ON(test_bit(R5_Wantcompute, &dev->flags));
2661        BUG_ON(test_bit(R5_Wantread, &dev->flags));
2662        if ((s->uptodate == disks - 1) &&
2663            (s->failed && (disk_idx == s->failed_num[0] ||
2664                   disk_idx == s->failed_num[1]))) {
2665            /* have disk failed, and we're requested to fetch it;
2666             * do compute it
2667             */
2668            pr_debug("Computing stripe %llu block %d\n",
2669                   (unsigned long long)sh->sector, disk_idx);
2670            set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2671            set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
2672            set_bit(R5_Wantcompute, &dev->flags);
2673            sh->ops.target = disk_idx;
2674            sh->ops.target2 = -1; /* no 2nd target */
2675            s->req_compute = 1;
2676            /* Careful: from this point on 'uptodate' is in the eye
2677             * of raid_run_ops which services 'compute' operations
2678             * before writes. R5_Wantcompute flags a block that will
2679             * be R5_UPTODATE by the time it is needed for a
2680             * subsequent operation.
2681             */
2682            s->uptodate++;
2683            return 1;
2684        } else if (s->uptodate == disks-2 && s->failed >= 2) {
2685            /* Computing 2-failure is *very* expensive; only
2686             * do it if failed >= 2
2687             */
2688            int other;
2689            for (other = disks; other--; ) {
2690                if (other == disk_idx)
2691                    continue;
2692                if (!test_bit(R5_UPTODATE,
2693                      &sh->dev[other].flags))
2694                    break;
2695            }
2696            BUG_ON(other < 0);
2697            pr_debug("Computing stripe %llu blocks %d,%d\n",
2698                   (unsigned long long)sh->sector,
2699                   disk_idx, other);
2700            set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2701            set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
2702            set_bit(R5_Wantcompute, &sh->dev[disk_idx].flags);
2703            set_bit(R5_Wantcompute, &sh->dev[other].flags);
2704            sh->ops.target = disk_idx;
2705            sh->ops.target2 = other;
2706            s->uptodate += 2;
2707            s->req_compute = 1;
2708            return 1;
2709        } else if (test_bit(R5_Insync, &dev->flags)) {
2710            set_bit(R5_LOCKED, &dev->flags);
2711            set_bit(R5_Wantread, &dev->flags);
2712            s->locked++;
2713            pr_debug("Reading block %d (sync=%d)\n",
2714                disk_idx, s->syncing);
2715        }
2716    }
2717
2718    return 0;
2719}
2720
2721/**
2722 * handle_stripe_fill - read or compute data to satisfy pending requests.
2723 */
2724static void handle_stripe_fill(struct stripe_head *sh,
2725                   struct stripe_head_state *s,
2726                   int disks)
2727{
2728    int i;
2729
2730    /* look for blocks to read/compute, skip this if a compute
2731     * is already in flight, or if the stripe contents are in the
2732     * midst of changing due to a write
2733     */
2734    if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state &&
2735        !sh->reconstruct_state)
2736        for (i = disks; i--; )
2737            if (fetch_block(sh, s, i, disks))
2738                break;
2739    set_bit(STRIPE_HANDLE, &sh->state);
2740}
2741
2742
2743/* handle_stripe_clean_event
2744 * any written block on an uptodate or failed drive can be returned.
2745 * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
2746 * never LOCKED, so we don't need to test 'failed' directly.
2747 */
2748static void handle_stripe_clean_event(struct r5conf *conf,
2749    struct stripe_head *sh, int disks, struct bio **return_bi)
2750{
2751    int i;
2752    struct r5dev *dev;
2753    int discard_pending = 0;
2754
2755    for (i = disks; i--; )
2756        if (sh->dev[i].written) {
2757            dev = &sh->dev[i];
2758            if (!test_bit(R5_LOCKED, &dev->flags) &&
2759                (test_bit(R5_UPTODATE, &dev->flags) ||
2760                 test_bit(R5_Discard, &dev->flags))) {
2761                /* We can return any write requests */
2762                struct bio *wbi, *wbi2;
2763                pr_debug("Return write for disc %d\n", i);
2764                if (test_and_clear_bit(R5_Discard, &dev->flags))
2765                    clear_bit(R5_UPTODATE, &dev->flags);
2766                wbi = dev->written;
2767                dev->written = NULL;
2768                while (wbi && wbi->bi_sector <
2769                    dev->sector + STRIPE_SECTORS) {
2770                    wbi2 = r5_next_bio(wbi, dev->sector);
2771                    if (!raid5_dec_bi_active_stripes(wbi)) {
2772                        md_write_end(conf->mddev);
2773                        wbi->bi_next = *return_bi;
2774                        *return_bi = wbi;
2775                    }
2776                    wbi = wbi2;
2777                }
2778                bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2779                        STRIPE_SECTORS,
2780                     !test_bit(STRIPE_DEGRADED, &sh->state),
2781                        0);
2782            } else if (test_bit(R5_Discard, &dev->flags))
2783                discard_pending = 1;
2784        }
2785    if (!discard_pending &&
2786        test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags)) {
2787        clear_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
2788        clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
2789        if (sh->qd_idx >= 0) {
2790            clear_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
2791            clear_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags);
2792        }
2793        /* now that discard is done we can proceed with any sync */
2794        clear_bit(STRIPE_DISCARD, &sh->state);
2795        if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state))
2796            set_bit(STRIPE_HANDLE, &sh->state);
2797
2798    }
2799
2800    if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
2801        if (atomic_dec_and_test(&conf->pending_full_writes))
2802            md_wakeup_thread(conf->mddev->thread);
2803}
2804
2805static void handle_stripe_dirtying(struct r5conf *conf,
2806                   struct stripe_head *sh,
2807                   struct stripe_head_state *s,
2808                   int disks)
2809{
2810    int rmw = 0, rcw = 0, i;
2811    sector_t recovery_cp = conf->mddev->recovery_cp;
2812
2813    /* RAID6 requires 'rcw' in current implementation.
2814     * Otherwise, check whether resync is now happening or should start.
2815     * If yes, then the array is dirty (after unclean shutdown or
2816     * initial creation), so parity in some stripes might be inconsistent.
2817     * In this case, we need to always do reconstruct-write, to ensure
2818     * that in case of drive failure or read-error correction, we
2819     * generate correct data from the parity.
2820     */
2821    if (conf->max_degraded == 2 ||
2822        (recovery_cp < MaxSector && sh->sector >= recovery_cp)) {
2823        /* Calculate the real rcw later - for now make it
2824         * look like rcw is cheaper
2825         */
2826        rcw = 1; rmw = 2;
2827        pr_debug("force RCW max_degraded=%u, recovery_cp=%llu sh->sector=%llu\n",
2828             conf->max_degraded, (unsigned long long)recovery_cp,
2829             (unsigned long long)sh->sector);
2830    } else for (i = disks; i--; ) {
2831        /* would I have to read this buffer for read_modify_write */
2832        struct r5dev *dev = &sh->dev[i];
2833        if ((dev->towrite || i == sh->pd_idx) &&
2834            !test_bit(R5_LOCKED, &dev->flags) &&
2835            !(test_bit(R5_UPTODATE, &dev->flags) ||
2836              test_bit(R5_Wantcompute, &dev->flags))) {
2837            if (test_bit(R5_Insync, &dev->flags))
2838                rmw++;
2839            else
2840                rmw += 2*disks; /* cannot read it */
2841        }
2842        /* Would I have to read this buffer for reconstruct_write */
2843        if (!test_bit(R5_OVERWRITE, &dev->flags) && i != sh->pd_idx &&
2844            !test_bit(R5_LOCKED, &dev->flags) &&
2845            !(test_bit(R5_UPTODATE, &dev->flags) ||
2846            test_bit(R5_Wantcompute, &dev->flags))) {
2847            if (test_bit(R5_Insync, &dev->flags)) rcw++;
2848            else
2849                rcw += 2*disks;
2850        }
2851    }
2852    pr_debug("for sector %llu, rmw=%d rcw=%d\n",
2853        (unsigned long long)sh->sector, rmw, rcw);
2854    set_bit(STRIPE_HANDLE, &sh->state);
2855    if (rmw < rcw && rmw > 0) {
2856        /* prefer read-modify-write, but need to get some data */
2857        if (conf->mddev->queue)
2858            blk_add_trace_msg(conf->mddev->queue,
2859                      "raid5 rmw %llu %d",
2860                      (unsigned long long)sh->sector, rmw);
2861        for (i = disks; i--; ) {
2862            struct r5dev *dev = &sh->dev[i];
2863            if ((dev->towrite || i == sh->pd_idx) &&
2864                !test_bit(R5_LOCKED, &dev->flags) &&
2865                !(test_bit(R5_UPTODATE, &dev->flags) ||
2866                test_bit(R5_Wantcompute, &dev->flags)) &&
2867                test_bit(R5_Insync, &dev->flags)) {
2868                if (
2869                  test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2870                    pr_debug("Read_old block "
2871                         "%d for r-m-w\n", i);
2872                    set_bit(R5_LOCKED, &dev->flags);
2873                    set_bit(R5_Wantread, &dev->flags);
2874                    s->locked++;
2875                } else {
2876                    set_bit(STRIPE_DELAYED, &sh->state);
2877                    set_bit(STRIPE_HANDLE, &sh->state);
2878                }
2879            }
2880        }
2881    }
2882    if (rcw <= rmw && rcw > 0) {
2883        /* want reconstruct write, but need to get some data */
2884        int qread =0;
2885        rcw = 0;
2886        for (i = disks; i--; ) {
2887            struct r5dev *dev = &sh->dev[i];
2888            if (!test_bit(R5_OVERWRITE, &dev->flags) &&
2889                i != sh->pd_idx && i != sh->qd_idx &&
2890                !test_bit(R5_LOCKED, &dev->flags) &&
2891                !(test_bit(R5_UPTODATE, &dev->flags) ||
2892                  test_bit(R5_Wantcompute, &dev->flags))) {
2893                rcw++;
2894                if (!test_bit(R5_Insync, &dev->flags))
2895                    continue; /* it's a failed drive */
2896                if (
2897                  test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2898                    pr_debug("Read_old block "
2899                        "%d for Reconstruct\n", i);
2900                    set_bit(R5_LOCKED, &dev->flags);
2901                    set_bit(R5_Wantread, &dev->flags);
2902                    s->locked++;
2903                    qread++;
2904                } else {
2905                    set_bit(STRIPE_DELAYED, &sh->state);
2906                    set_bit(STRIPE_HANDLE, &sh->state);
2907                }
2908            }
2909        }
2910        if (rcw && conf->mddev->queue)
2911            blk_add_trace_msg(conf->mddev->queue, "raid5 rcw %llu %d %d %d",
2912                      (unsigned long long)sh->sector,
2913                      rcw, qread, test_bit(STRIPE_DELAYED, &sh->state));
2914    }
2915    /* now if nothing is locked, and if we have enough data,
2916     * we can start a write request
2917     */
2918    /* since handle_stripe can be called at any time we need to handle the
2919     * case where a compute block operation has been submitted and then a
2920     * subsequent call wants to start a write request. raid_run_ops only
2921     * handles the case where compute block and reconstruct are requested
2922     * simultaneously. If this is not the case then new writes need to be
2923     * held off until the compute completes.
2924     */
2925    if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) &&
2926        (s->locked == 0 && (rcw == 0 || rmw == 0) &&
2927        !test_bit(STRIPE_BIT_DELAY, &sh->state)))
2928        schedule_reconstruction(sh, s, rcw == 0, 0);
2929}
2930
2931static void handle_parity_checks5(struct r5conf *conf, struct stripe_head *sh,
2932                struct stripe_head_state *s, int disks)
2933{
2934    struct r5dev *dev = NULL;
2935
2936    set_bit(STRIPE_HANDLE, &sh->state);
2937
2938    switch (sh->check_state) {
2939    case check_state_idle:
2940        /* start a new check operation if there are no failures */
2941        if (s->failed == 0) {
2942            BUG_ON(s->uptodate != disks);
2943            sh->check_state = check_state_run;
2944            set_bit(STRIPE_OP_CHECK, &s->ops_request);
2945            clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
2946            s->uptodate--;
2947            break;
2948        }
2949        dev = &sh->dev[s->failed_num[0]];
2950        /* fall through */
2951    case check_state_compute_result:
2952        sh->check_state = check_state_idle;
2953        if (!dev)
2954            dev = &sh->dev[sh->pd_idx];
2955
2956        /* check that a write has not made the stripe insync */
2957        if (test_bit(STRIPE_INSYNC, &sh->state))
2958            break;
2959
2960        /* either failed parity check, or recovery is happening */
2961        BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
2962        BUG_ON(s->uptodate != disks);
2963
2964        set_bit(R5_LOCKED, &dev->flags);
2965        s->locked++;
2966        set_bit(R5_Wantwrite, &dev->flags);
2967
2968        clear_bit(STRIPE_DEGRADED, &sh->state);
2969        set_bit(STRIPE_INSYNC, &sh->state);
2970        break;
2971    case check_state_run:
2972        break; /* we will be called again upon completion */
2973    case check_state_check_result:
2974        sh->check_state = check_state_idle;
2975
2976        /* if a failure occurred during the check operation, leave
2977         * STRIPE_INSYNC not set and let the stripe be handled again
2978         */
2979        if (s->failed)
2980            break;
2981
2982        /* handle a successful check operation, if parity is correct
2983         * we are done. Otherwise update the mismatch count and repair
2984         * parity if !MD_RECOVERY_CHECK
2985         */
2986        if ((sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) == 0)
2987            /* parity is correct (on disc,
2988             * not in buffer any more)
2989             */
2990            set_bit(STRIPE_INSYNC, &sh->state);
2991        else {
2992            atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
2993            if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
2994                /* don't try to repair!! */
2995                set_bit(STRIPE_INSYNC, &sh->state);
2996            else {
2997                sh->check_state = check_state_compute_run;
2998                set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2999                set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3000                set_bit(R5_Wantcompute,
3001                    &sh->dev[sh->pd_idx].flags);
3002                sh->ops.target = sh->pd_idx;
3003                sh->ops.target2 = -1;
3004                s->uptodate++;
3005            }
3006        }
3007        break;
3008    case check_state_compute_run:
3009        break;
3010    default:
3011        printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
3012               __func__, sh->check_state,
3013               (unsigned long long) sh->sector);
3014        BUG();
3015    }
3016}
3017
3018
3019static void handle_parity_checks6(struct r5conf *conf, struct stripe_head *sh,
3020                  struct stripe_head_state *s,
3021                  int disks)
3022{
3023    int pd_idx = sh->pd_idx;
3024    int qd_idx = sh->qd_idx;
3025    struct r5dev *dev;
3026
3027    set_bit(STRIPE_HANDLE, &sh->state);
3028
3029    BUG_ON(s->failed > 2);
3030
3031    /* Want to check and possibly repair P and Q.
3032     * However there could be one 'failed' device, in which
3033     * case we can only check one of them, possibly using the
3034     * other to generate missing data
3035     */
3036
3037    switch (sh->check_state) {
3038    case check_state_idle:
3039        /* start a new check operation if there are < 2 failures */
3040        if (s->failed == s->q_failed) {
3041            /* The only possible failed device holds Q, so it
3042             * makes sense to check P (If anything else were failed,
3043             * we would have used P to recreate it).
3044             */
3045            sh->check_state = check_state_run;
3046        }
3047        if (!s->q_failed && s->failed < 2) {
3048            /* Q is not failed, and we didn't use it to generate
3049             * anything, so it makes sense to check it
3050             */
3051            if (sh->check_state == check_state_run)
3052                sh->check_state = check_state_run_pq;
3053            else
3054                sh->check_state = check_state_run_q;
3055        }
3056
3057        /* discard potentially stale zero_sum_result */
3058        sh->ops.zero_sum_result = 0;
3059
3060        if (sh->check_state == check_state_run) {
3061            /* async_xor_zero_sum destroys the contents of P */
3062            clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
3063            s->uptodate--;
3064        }
3065        if (sh->check_state >= check_state_run &&
3066            sh->check_state <= check_state_run_pq) {
3067            /* async_syndrome_zero_sum preserves P and Q, so
3068             * no need to mark them !uptodate here
3069             */
3070            set_bit(STRIPE_OP_CHECK, &s->ops_request);
3071            break;
3072        }
3073
3074        /* we have 2-disk failure */
3075        BUG_ON(s->failed != 2);
3076        /* fall through */
3077    case check_state_compute_result:
3078        sh->check_state = check_state_idle;
3079
3080        /* check that a write has not made the stripe insync */
3081        if (test_bit(STRIPE_INSYNC, &sh->state))
3082            break;
3083
3084        /* now write out any block on a failed drive,
3085         * or P or Q if they were recomputed
3086         */
3087        BUG_ON(s->uptodate < disks - 1); /* We don't need Q to recover */
3088        if (s->failed == 2) {
3089            dev = &sh->dev[s->failed_num[1]];
3090            s->locked++;
3091            set_bit(R5_LOCKED, &dev->flags);
3092            set_bit(R5_Wantwrite, &dev->flags);
3093        }
3094        if (s->failed >= 1) {
3095            dev = &sh->dev[s->failed_num[0]];
3096            s->locked++;
3097            set_bit(R5_LOCKED, &dev->flags);
3098            set_bit(R5_Wantwrite, &dev->flags);
3099        }
3100        if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
3101            dev = &sh->dev[pd_idx];
3102            s->locked++;
3103            set_bit(R5_LOCKED, &dev->flags);
3104            set_bit(R5_Wantwrite, &dev->flags);
3105        }
3106        if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
3107            dev = &sh->dev[qd_idx];
3108            s->locked++;
3109            set_bit(R5_LOCKED, &dev->flags);
3110            set_bit(R5_Wantwrite, &dev->flags);
3111        }
3112        clear_bit(STRIPE_DEGRADED, &sh->state);
3113
3114        set_bit(STRIPE_INSYNC, &sh->state);
3115        break;
3116    case check_state_run:
3117    case check_state_run_q:
3118    case check_state_run_pq:
3119        break; /* we will be called again upon completion */
3120    case check_state_check_result:
3121        sh->check_state = check_state_idle;
3122
3123        /* handle a successful check operation, if parity is correct
3124         * we are done. Otherwise update the mismatch count and repair
3125         * parity if !MD_RECOVERY_CHECK
3126         */
3127        if (sh->ops.zero_sum_result == 0) {
3128            /* both parities are correct */
3129            if (!s->failed)
3130                set_bit(STRIPE_INSYNC, &sh->state);
3131            else {
3132                /* in contrast to the raid5 case we can validate
3133                 * parity, but still have a failure to write
3134                 * back
3135                 */
3136                sh->check_state = check_state_compute_result;
3137                /* Returning at this point means that we may go
3138                 * off and bring p and/or q uptodate again so
3139                 * we make sure to check zero_sum_result again
3140                 * to verify if p or q need writeback
3141                 */
3142            }
3143        } else {
3144            atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
3145            if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
3146                /* don't try to repair!! */
3147                set_bit(STRIPE_INSYNC, &sh->state);
3148            else {
3149                int *target = &sh->ops.target;
3150
3151                sh->ops.target = -1;
3152                sh->ops.target2 = -1;
3153                sh->check_state = check_state_compute_run;
3154                set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3155                set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3156                if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
3157                    set_bit(R5_Wantcompute,
3158                        &sh->dev[pd_idx].flags);
3159                    *target = pd_idx;
3160                    target = &sh->ops.target2;
3161                    s->uptodate++;
3162                }
3163                if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
3164                    set_bit(R5_Wantcompute,
3165                        &sh->dev[qd_idx].flags);
3166                    *target = qd_idx;
3167                    s->uptodate++;
3168                }
3169            }
3170        }
3171        break;
3172    case check_state_compute_run:
3173        break;
3174    default:
3175        printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
3176               __func__, sh->check_state,
3177               (unsigned long long) sh->sector);
3178        BUG();
3179    }
3180}
3181
3182static void handle_stripe_expansion(struct r5conf *conf, struct stripe_head *sh)
3183{
3184    int i;
3185
3186    /* We have read all the blocks in this stripe and now we need to
3187     * copy some of them into a target stripe for expand.
3188     */
3189    struct dma_async_tx_descriptor *tx = NULL;
3190    clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3191    for (i = 0; i < sh->disks; i++)
3192        if (i != sh->pd_idx && i != sh->qd_idx) {
3193            int dd_idx, j;
3194            struct stripe_head *sh2;
3195            struct async_submit_ctl submit;
3196
3197            sector_t bn = compute_blocknr(sh, i, 1);
3198            sector_t s = raid5_compute_sector(conf, bn, 0,
3199                              &dd_idx, NULL);
3200            sh2 = get_active_stripe(conf, s, 0, 1, 1);
3201            if (sh2 == NULL)
3202                /* so far only the early blocks of this stripe
3203                 * have been requested. When later blocks
3204                 * get requested, we will try again
3205                 */
3206                continue;
3207            if (!test_bit(STRIPE_EXPANDING, &sh2->state) ||
3208               test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
3209                /* must have already done this block */
3210                release_stripe(sh2);
3211                continue;
3212            }
3213
3214            /* place all the copies on one channel */
3215            init_async_submit(&submit, 0, tx, NULL, NULL, NULL);
3216            tx = async_memcpy(sh2->dev[dd_idx].page,
3217                      sh->dev[i].page, 0, 0, STRIPE_SIZE,
3218                      &submit);
3219
3220            set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
3221            set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
3222            for (j = 0; j < conf->raid_disks; j++)
3223                if (j != sh2->pd_idx &&
3224                    j != sh2->qd_idx &&
3225                    !test_bit(R5_Expanded, &sh2->dev[j].flags))
3226                    break;
3227            if (j == conf->raid_disks) {
3228                set_bit(STRIPE_EXPAND_READY, &sh2->state);
3229                set_bit(STRIPE_HANDLE, &sh2->state);
3230            }
3231            release_stripe(sh2);
3232
3233        }
3234    /* done submitting copies, wait for them to complete */
3235    async_tx_quiesce(&tx);
3236}
3237
3238/*
3239 * handle_stripe - do things to a stripe.
3240 *
3241 * We lock the stripe by setting STRIPE_ACTIVE and then examine the
3242 * state of various bits to see what needs to be done.
3243 * Possible results:
3244 * return some read requests which now have data
3245 * return some write requests which are safely on storage
3246 * schedule a read on some buffers
3247 * schedule a write of some buffers
3248 * return confirmation of parity correctness
3249 *
3250 */
3251
3252static void analyse_stripe(struct stripe_head *sh, struct stripe_head_state *s)
3253{
3254    struct r5conf *conf = sh->raid_conf;
3255    int disks = sh->disks;
3256    struct r5dev *dev;
3257    int i;
3258    int do_recovery = 0;
3259
3260    memset(s, 0, sizeof(*s));
3261
3262    s->expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3263    s->expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
3264    s->failed_num[0] = -1;
3265    s->failed_num[1] = -1;
3266
3267    /* Now to look around and see what can be done */
3268    rcu_read_lock();
3269    for (i=disks; i--; ) {
3270        struct md_rdev *rdev;
3271        sector_t first_bad;
3272        int bad_sectors;
3273        int is_bad = 0;
3274
3275        dev = &sh->dev[i];
3276
3277        pr_debug("check %d: state 0x%lx read %p write %p written %p\n",
3278             i, dev->flags,
3279             dev->toread, dev->towrite, dev->written);
3280        /* maybe we can reply to a read
3281         *
3282         * new wantfill requests are only permitted while
3283         * ops_complete_biofill is guaranteed to be inactive
3284         */
3285        if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
3286            !test_bit(STRIPE_BIOFILL_RUN, &sh->state))
3287            set_bit(R5_Wantfill, &dev->flags);
3288
3289        /* now count some things */
3290        if (test_bit(R5_LOCKED, &dev->flags))
3291            s->locked++;
3292        if (test_bit(R5_UPTODATE, &dev->flags))
3293            s->uptodate++;
3294        if (test_bit(R5_Wantcompute, &dev->flags)) {
3295            s->compute++;
3296            BUG_ON(s->compute > 2);
3297        }
3298
3299        if (test_bit(R5_Wantfill, &dev->flags))
3300            s->to_fill++;
3301        else if (dev->toread)
3302            s->to_read++;
3303        if (dev->towrite) {
3304            s->to_write++;
3305            if (!test_bit(R5_OVERWRITE, &dev->flags))
3306                s->non_overwrite++;
3307        }
3308        if (dev->written)
3309            s->written++;
3310        /* Prefer to use the replacement for reads, but only
3311         * if it is recovered enough and has no bad blocks.
3312         */
3313        rdev = rcu_dereference(conf->disks[i].replacement);
3314        if (rdev && !test_bit(Faulty, &rdev->flags) &&
3315            rdev->recovery_offset >= sh->sector + STRIPE_SECTORS &&
3316            !is_badblock(rdev, sh->sector, STRIPE_SECTORS,
3317                 &first_bad, &bad_sectors))
3318            set_bit(R5_ReadRepl, &dev->flags);
3319        else {
3320            if (rdev)
3321                set_bit(R5_NeedReplace, &dev->flags);
3322            rdev = rcu_dereference(conf->disks[i].rdev);
3323            clear_bit(R5_ReadRepl, &dev->flags);
3324        }
3325        if (rdev && test_bit(Faulty, &rdev->flags))
3326            rdev = NULL;
3327        if (rdev) {
3328            is_bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
3329                         &first_bad, &bad_sectors);
3330            if (s->blocked_rdev == NULL
3331                && (test_bit(Blocked, &rdev->flags)
3332                || is_bad < 0)) {
3333                if (is_bad < 0)
3334                    set_bit(BlockedBadBlocks,
3335                        &rdev->flags);
3336                s->blocked_rdev = rdev;
3337                atomic_inc(&rdev->nr_pending);
3338            }
3339        }
3340        clear_bit(R5_Insync, &dev->flags);
3341        if (!rdev)
3342            /* Not in-sync */;
3343        else if (is_bad) {
3344            /* also not in-sync */
3345            if (!test_bit(WriteErrorSeen, &rdev->flags) &&
3346                test_bit(R5_UPTODATE, &dev->flags)) {
3347                /* treat as in-sync, but with a read error
3348                 * which we can now try to correct
3349                 */
3350                set_bit(R5_Insync, &dev->flags);
3351                set_bit(R5_ReadError, &dev->flags);
3352            }
3353        } else if (test_bit(In_sync, &rdev->flags))
3354            set_bit(R5_Insync, &dev->flags);
3355        else if (sh->sector + STRIPE_SECTORS <= rdev->recovery_offset)
3356            /* in sync if before recovery_offset */
3357            set_bit(R5_Insync, &dev->flags);
3358        else if (test_bit(R5_UPTODATE, &dev->flags) &&
3359             test_bit(R5_Expanded, &dev->flags))
3360            /* If we've reshaped into here, we assume it is Insync.
3361             * We will shortly update recovery_offset to make
3362             * it official.
3363             */
3364            set_bit(R5_Insync, &dev->flags);
3365
3366        if (rdev && test_bit(R5_WriteError, &dev->flags)) {
3367            /* This flag does not apply to '.replacement'
3368             * only to .rdev, so make sure to check that*/
3369            struct md_rdev *rdev2 = rcu_dereference(
3370                conf->disks[i].rdev);
3371            if (rdev2 == rdev)
3372                clear_bit(R5_Insync, &dev->flags);
3373            if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
3374                s->handle_bad_blocks = 1;
3375                atomic_inc(&rdev2->nr_pending);
3376            } else
3377                clear_bit(R5_WriteError, &dev->flags);
3378        }
3379        if (rdev && test_bit(R5_MadeGood, &dev->flags)) {
3380            /* This flag does not apply to '.replacement'
3381             * only to .rdev, so make sure to check that*/
3382            struct md_rdev *rdev2 = rcu_dereference(
3383                conf->disks[i].rdev);
3384            if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
3385                s->handle_bad_blocks = 1;
3386                atomic_inc(&rdev2->nr_pending);
3387            } else
3388                clear_bit(R5_MadeGood, &dev->flags);
3389        }
3390        if (test_bit(R5_MadeGoodRepl, &dev->flags)) {
3391            struct md_rdev *rdev2 = rcu_dereference(
3392                conf->disks[i].replacement);
3393            if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
3394                s->handle_bad_blocks = 1;
3395                atomic_inc(&rdev2->nr_pending);
3396            } else
3397                clear_bit(R5_MadeGoodRepl, &dev->flags);
3398        }
3399        if (!test_bit(R5_Insync, &dev->flags)) {
3400            /* The ReadError flag will just be confusing now */
3401            clear_bit(R5_ReadError, &dev->flags);
3402            clear_bit(R5_ReWrite, &dev->flags);
3403        }
3404        if (test_bit(R5_ReadError, &dev->flags))
3405            clear_bit(R5_Insync, &dev->flags);
3406        if (!test_bit(R5_Insync, &dev->flags)) {
3407            if (s->failed < 2)
3408                s->failed_num[s->failed] = i;
3409            s->failed++;
3410            if (rdev && !test_bit(Faulty, &rdev->flags))
3411                do_recovery = 1;
3412        }
3413    }
3414    if (test_bit(STRIPE_SYNCING, &sh->state)) {
3415        /* If there is a failed device being replaced,
3416         * we must be recovering.
3417         * else if we are after recovery_cp, we must be syncing
3418         * else if MD_RECOVERY_REQUESTED is set, we also are syncing.
3419         * else we can only be replacing
3420         * sync and recovery both need to read all devices, and so
3421         * use the same flag.
3422         */
3423        if (do_recovery ||
3424            sh->sector >= conf->mddev->recovery_cp ||
3425            test_bit(MD_RECOVERY_REQUESTED, &(conf->mddev->recovery)))
3426            s->syncing = 1;
3427        else
3428            s->replacing = 1;
3429    }
3430    rcu_read_unlock();
3431}
3432
3433static void handle_stripe(struct stripe_head *sh)
3434{
3435    struct stripe_head_state s;
3436    struct r5conf *conf = sh->raid_conf;
3437    int i;
3438    int prexor;
3439    int disks = sh->disks;
3440    struct r5dev *pdev, *qdev;
3441
3442    clear_bit(STRIPE_HANDLE, &sh->state);
3443    if (test_and_set_bit_lock(STRIPE_ACTIVE, &sh->state)) {
3444        /* already being handled, ensure it gets handled
3445         * again when current action finishes */
3446        set_bit(STRIPE_HANDLE, &sh->state);
3447        return;
3448    }
3449
3450    if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
3451        spin_lock(&sh->stripe_lock);
3452        /* Cannot process 'sync' concurrently with 'discard' */
3453        if (!test_bit(STRIPE_DISCARD, &sh->state) &&
3454            test_and_clear_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
3455            set_bit(STRIPE_SYNCING, &sh->state);
3456            clear_bit(STRIPE_INSYNC, &sh->state);
3457        }
3458        spin_unlock(&sh->stripe_lock);
3459    }
3460    clear_bit(STRIPE_DELAYED, &sh->state);
3461
3462    pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
3463        "pd_idx=%d, qd_idx=%d\n, check:%d, reconstruct:%d\n",
3464           (unsigned long long)sh->sector, sh->state,
3465           atomic_read(&sh->count), sh->pd_idx, sh->qd_idx,
3466           sh->check_state, sh->reconstruct_state);
3467
3468    analyse_stripe(sh, &s);
3469
3470    if (s.handle_bad_blocks) {
3471        set_bit(STRIPE_HANDLE, &sh->state);
3472        goto finish;
3473    }
3474
3475    if (unlikely(s.blocked_rdev)) {
3476        if (s.syncing || s.expanding || s.expanded ||
3477            s.replacing || s.to_write || s.written) {
3478            set_bit(STRIPE_HANDLE, &sh->state);
3479            goto finish;
3480        }
3481        /* There is nothing for the blocked_rdev to block */
3482        rdev_dec_pending(s.blocked_rdev, conf->mddev);
3483        s.blocked_rdev = NULL;
3484    }
3485
3486    if (s.to_fill && !test_bit(STRIPE_BIOFILL_RUN, &sh->state)) {
3487        set_bit(STRIPE_OP_BIOFILL, &s.ops_request);
3488        set_bit(STRIPE_BIOFILL_RUN, &sh->state);
3489    }
3490
3491    pr_debug("locked=%d uptodate=%d to_read=%d"
3492           " to_write=%d failed=%d failed_num=%d,%d\n",
3493           s.locked, s.uptodate, s.to_read, s.to_write, s.failed,
3494           s.failed_num[0], s.failed_num[1]);
3495    /* check if the array has lost more than max_degraded devices and,
3496     * if so, some requests might need to be failed.
3497     */
3498    if (s.failed > conf->max_degraded) {
3499        sh->check_state = 0;
3500        sh->reconstruct_state = 0;
3501        if (s.to_read+s.to_write+s.written)
3502            handle_failed_stripe(conf, sh, &s, disks, &s.return_bi);
3503        if (s.syncing + s.replacing)
3504            handle_failed_sync(conf, sh, &s);
3505    }
3506
3507    /* Now we check to see if any write operations have recently
3508     * completed
3509     */
3510    prexor = 0;
3511    if (sh->reconstruct_state == reconstruct_state_prexor_drain_result)
3512        prexor = 1;
3513    if (sh->reconstruct_state == reconstruct_state_drain_result ||
3514        sh->reconstruct_state == reconstruct_state_prexor_drain_result) {
3515        sh->reconstruct_state = reconstruct_state_idle;
3516
3517        /* All the 'written' buffers and the parity block are ready to
3518         * be written back to disk
3519         */
3520        BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags) &&
3521               !test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags));
3522        BUG_ON(sh->qd_idx >= 0 &&
3523               !test_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags) &&
3524               !test_bit(R5_Discard, &sh->dev[sh->qd_idx].flags));
3525        for (i = disks; i--; ) {
3526            struct r5dev *dev = &sh->dev[i];
3527            if (test_bit(R5_LOCKED, &dev->flags) &&
3528                (i == sh->pd_idx || i == sh->qd_idx ||
3529                 dev->written)) {
3530                pr_debug("Writing block %d\n", i);
3531                set_bit(R5_Wantwrite, &dev->flags);
3532                if (prexor)
3533                    continue;
3534                if (!test_bit(R5_Insync, &dev->flags) ||
3535                    ((i == sh->pd_idx || i == sh->qd_idx) &&
3536                     s.failed == 0))
3537                    set_bit(STRIPE_INSYNC, &sh->state);
3538            }
3539        }
3540        if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3541            s.dec_preread_active = 1;
3542    }
3543
3544    /*
3545     * might be able to return some write requests if the parity blocks
3546     * are safe, or on a failed drive
3547     */
3548    pdev = &sh->dev[sh->pd_idx];
3549    s.p_failed = (s.failed >= 1 && s.failed_num[0] == sh->pd_idx)
3550        || (s.failed >= 2 && s.failed_num[1] == sh->pd_idx);
3551    qdev = &sh->dev[sh->qd_idx];
3552    s.q_failed = (s.failed >= 1 && s.failed_num[0] == sh->qd_idx)
3553        || (s.failed >= 2 && s.failed_num[1] == sh->qd_idx)
3554        || conf->level < 6;
3555
3556    if (s.written &&
3557        (s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
3558                 && !test_bit(R5_LOCKED, &pdev->flags)
3559                 && (test_bit(R5_UPTODATE, &pdev->flags) ||
3560                 test_bit(R5_Discard, &pdev->flags))))) &&
3561        (s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
3562                 && !test_bit(R5_LOCKED, &qdev->flags)
3563                 && (test_bit(R5_UPTODATE, &qdev->flags) ||
3564                 test_bit(R5_Discard, &qdev->flags))))))
3565        handle_stripe_clean_event(conf, sh, disks, &s.return_bi);
3566
3567    /* Now we might consider reading some blocks, either to check/generate
3568     * parity, or to satisfy requests
3569     * or to load a block that is being partially written.
3570     */
3571    if (s.to_read || s.non_overwrite
3572        || (conf->level == 6 && s.to_write && s.failed)
3573        || (s.syncing && (s.uptodate + s.compute < disks))
3574        || s.replacing
3575        || s.expanding)
3576        handle_stripe_fill(sh, &s, disks);
3577
3578    /* Now to consider new write requests and what else, if anything
3579     * should be read. We do not handle new writes when:
3580     * 1/ A 'write' operation (copy+xor) is already in flight.
3581     * 2/ A 'check' operation is in flight, as it may clobber the parity
3582     * block.
3583     */
3584    if (s.to_write && !sh->reconstruct_state && !sh->check_state)
3585        handle_stripe_dirtying(conf, sh, &s, disks);
3586
3587    /* maybe we need to check and possibly fix the parity for this stripe
3588     * Any reads will already have been scheduled, so we just see if enough
3589     * data is available. The parity check is held off while parity
3590     * dependent operations are in flight.
3591     */
3592    if (sh->check_state ||
3593        (s.syncing && s.locked == 0 &&
3594         !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
3595         !test_bit(STRIPE_INSYNC, &sh->state))) {
3596        if (conf->level == 6)
3597            handle_parity_checks6(conf, sh, &s, disks);
3598        else
3599            handle_parity_checks5(conf, sh, &s, disks);
3600    }
3601
3602    if (s.replacing && s.locked == 0
3603        && !test_bit(STRIPE_INSYNC, &sh->state)) {
3604        /* Write out to replacement devices where possible */
3605        for (i = 0; i < conf->raid_disks; i++)
3606            if (test_bit(R5_UPTODATE, &sh->dev[i].flags) &&
3607                test_bit(R5_NeedReplace, &sh->dev[i].flags)) {
3608                set_bit(R5_WantReplace, &sh->dev[i].flags);
3609                set_bit(R5_LOCKED, &sh->dev[i].flags);
3610                s.locked++;
3611            }
3612        set_bit(STRIPE_INSYNC, &sh->state);
3613    }
3614    if ((s.syncing || s.replacing) && s.locked == 0 &&
3615        test_bit(STRIPE_INSYNC, &sh->state)) {
3616        md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
3617        clear_bit(STRIPE_SYNCING, &sh->state);
3618        if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
3619            wake_up(&conf->wait_for_overlap);
3620    }
3621
3622    /* If the failed drives are just a ReadError, then we might need
3623     * to progress the repair/check process
3624     */
3625    if (s.failed <= conf->max_degraded && !conf->mddev->ro)
3626        for (i = 0; i < s.failed; i++) {
3627            struct r5dev *dev = &sh->dev[s.failed_num[i]];
3628            if (test_bit(R5_ReadError, &dev->flags)
3629                && !test_bit(R5_LOCKED, &dev->flags)
3630                && test_bit(R5_UPTODATE, &dev->flags)
3631                ) {
3632                if (!test_bit(R5_ReWrite, &dev->flags)) {
3633                    set_bit(R5_Wantwrite, &dev->flags);
3634                    set_bit(R5_ReWrite, &dev->flags);
3635                    set_bit(R5_LOCKED, &dev->flags);
3636                    s.locked++;
3637                } else {
3638                    /* let's read it back */
3639                    set_bit(R5_Wantread, &dev->flags);
3640                    set_bit(R5_LOCKED, &dev->flags);
3641                    s.locked++;
3642                }
3643            }
3644        }
3645
3646
3647    /* Finish reconstruct operations initiated by the expansion process */
3648    if (sh->reconstruct_state == reconstruct_state_result) {
3649        struct stripe_head *sh_src
3650            = get_active_stripe(conf, sh->sector, 1, 1, 1);
3651        if (sh_src && test_bit(STRIPE_EXPAND_SOURCE, &sh_src->state)) {
3652            /* sh cannot be written until sh_src has been read.
3653             * so arrange for sh to be delayed a little
3654             */
3655            set_bit(STRIPE_DELAYED, &sh->state);
3656            set_bit(STRIPE_HANDLE, &sh->state);
3657            if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE,
3658                          &sh_src->state))
3659                atomic_inc(&conf->preread_active_stripes);
3660            release_stripe(sh_src);
3661            goto finish;
3662        }
3663        if (sh_src)
3664            release_stripe(sh_src);
3665
3666        sh->reconstruct_state = reconstruct_state_idle;
3667        clear_bit(STRIPE_EXPANDING, &sh->state);
3668        for (i = conf->raid_disks; i--; ) {
3669            set_bit(R5_Wantwrite, &sh->dev[i].flags);
3670            set_bit(R5_LOCKED, &sh->dev[i].flags);
3671            s.locked++;
3672        }
3673    }
3674
3675    if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
3676        !sh->reconstruct_state) {
3677        /* Need to write out all blocks after computing parity */
3678        sh->disks = conf->raid_disks;
3679        stripe_set_idx(sh->sector, conf, 0, sh);
3680        schedule_reconstruction(sh, &s, 1, 1);
3681    } else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
3682        clear_bit(STRIPE_EXPAND_READY, &sh->state);
3683        atomic_dec(&conf->reshape_stripes);
3684        wake_up(&conf->wait_for_overlap);
3685        md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
3686    }
3687
3688    if (s.expanding && s.locked == 0 &&
3689        !test_bit(STRIPE_COMPUTE_RUN, &sh->state))
3690        handle_stripe_expansion(conf, sh);
3691
3692finish:
3693    /* wait for this device to become unblocked */
3694    if (unlikely(s.blocked_rdev)) {
3695        if (conf->mddev->external)
3696            md_wait_for_blocked_rdev(s.blocked_rdev,
3697                         conf->mddev);
3698        else
3699            /* Internal metadata will immediately
3700             * be written by raid5d, so we don't
3701             * need to wait here.
3702             */
3703            rdev_dec_pending(s.blocked_rdev,
3704                     conf->mddev);
3705    }
3706
3707    if (s.handle_bad_blocks)
3708        for (i = disks; i--; ) {
3709            struct md_rdev *rdev;
3710            struct r5dev *dev = &sh->dev[i];
3711            if (test_and_clear_bit(R5_WriteError, &dev->flags)) {
3712                /* We own a safe reference to the rdev */
3713                rdev = conf->disks[i].rdev;
3714                if (!rdev_set_badblocks(rdev, sh->sector,
3715                            STRIPE_SECTORS, 0))
3716                    md_error(conf->mddev, rdev);
3717                rdev_dec_pending(rdev, conf->mddev);
3718            }
3719            if (test_and_clear_bit(R5_MadeGood, &dev->flags)) {
3720                rdev = conf->disks[i].rdev;
3721                rdev_clear_badblocks(rdev, sh->sector,
3722                             STRIPE_SECTORS, 0);
3723                rdev_dec_pending(rdev, conf->mddev);
3724            }
3725            if (test_and_clear_bit(R5_MadeGoodRepl, &dev->flags)) {
3726                rdev = conf->disks[i].replacement;
3727                if (!rdev)
3728                    /* rdev have been moved down */
3729                    rdev = conf->disks[i].rdev;
3730                rdev_clear_badblocks(rdev, sh->sector,
3731                             STRIPE_SECTORS, 0);
3732                rdev_dec_pending(rdev, conf->mddev);
3733            }
3734        }
3735
3736    if (s.ops_request)
3737        raid_run_ops(sh, s.ops_request);
3738
3739    ops_run_io(sh, &s);
3740
3741    if (s.dec_preread_active) {
3742        /* We delay this until after ops_run_io so that if make_request
3743         * is waiting on a flush, it won't continue until the writes
3744         * have actually been submitted.
3745         */
3746        atomic_dec(&conf->preread_active_stripes);
3747        if (atomic_read(&conf->preread_active_stripes) <
3748            IO_THRESHOLD)
3749            md_wakeup_thread(conf->mddev->thread);
3750    }
3751
3752    return_io(s.return_bi);
3753
3754    clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
3755}
3756
3757static void raid5_activate_delayed(struct r5conf *conf)
3758{
3759    if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
3760        while (!list_empty(&conf->delayed_list)) {
3761            struct list_head *l = conf->delayed_list.next;
3762            struct stripe_head *sh;
3763            sh = list_entry(l, struct stripe_head, lru);
3764            list_del_init(l);
3765            clear_bit(STRIPE_DELAYED, &sh->state);
3766            if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3767                atomic_inc(&conf->preread_active_stripes);
3768            list_add_tail(&sh->lru, &conf->hold_list);
3769        }
3770    }
3771}
3772
3773static void activate_bit_delay(struct r5conf *conf)
3774{
3775    /* device_lock is held */
3776    struct list_head head;
3777    list_add(&head, &conf->bitmap_list);
3778    list_del_init(&conf->bitmap_list);
3779    while (!list_empty(&head)) {
3780        struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
3781        list_del_init(&sh->lru);
3782        atomic_inc(&sh->count);
3783        __release_stripe(conf, sh);
3784    }
3785}
3786
3787int md_raid5_congested(struct mddev *mddev, int bits)
3788{
3789    struct r5conf *conf = mddev->private;
3790
3791    /* No difference between reads and writes. Just check
3792     * how busy the stripe_cache is
3793     */
3794
3795    if (conf->inactive_blocked)
3796        return 1;
3797    if (conf->quiesce)
3798        return 1;
3799    if (list_empty_careful(&conf->inactive_list))
3800        return 1;
3801
3802    return 0;
3803}
3804EXPORT_SYMBOL_GPL(md_raid5_congested);
3805
3806static int raid5_congested(void *data, int bits)
3807{
3808    struct mddev *mddev = data;
3809
3810    return mddev_congested(mddev, bits) ||
3811        md_raid5_congested(mddev, bits);
3812}
3813
3814/* We want read requests to align with chunks where possible,
3815 * but write requests don't need to.
3816 */
3817static int raid5_mergeable_bvec(struct request_queue *q,
3818                struct bvec_merge_data *bvm,
3819                struct bio_vec *biovec)
3820{
3821    struct mddev *mddev = q->queuedata;
3822    sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
3823    int max;
3824    unsigned int chunk_sectors = mddev->chunk_sectors;
3825    unsigned int bio_sectors = bvm->bi_size >> 9;
3826
3827    if ((bvm->bi_rw & 1) == WRITE)
3828        return biovec->bv_len; /* always allow writes to be mergeable */
3829
3830    if (mddev->new_chunk_sectors < mddev->chunk_sectors)
3831        chunk_sectors = mddev->new_chunk_sectors;
3832    max = (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
3833    if (max < 0) max = 0;
3834    if (max <= biovec->bv_len && bio_sectors == 0)
3835        return biovec->bv_len;
3836    else
3837        return max;
3838}
3839
3840
3841static int in_chunk_boundary(struct mddev *mddev, struct bio *bio)
3842{
3843    sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
3844    unsigned int chunk_sectors = mddev->chunk_sectors;
3845    unsigned int bio_sectors = bio->bi_size >> 9;
3846
3847    if (mddev->new_chunk_sectors < mddev->chunk_sectors)
3848        chunk_sectors = mddev->new_chunk_sectors;
3849    return chunk_sectors >=
3850        ((sector & (chunk_sectors - 1)) + bio_sectors);
3851}
3852
3853/*
3854 * add bio to the retry LIFO ( in O(1) ... we are in interrupt )
3855 * later sampled by raid5d.
3856 */
3857static void add_bio_to_retry(struct bio *bi,struct r5conf *conf)
3858{
3859    unsigned long flags;
3860
3861    spin_lock_irqsave(&conf->device_lock, flags);
3862
3863    bi->bi_next = conf->retry_read_aligned_list;
3864    conf->retry_read_aligned_list = bi;
3865
3866    spin_unlock_irqrestore(&conf->device_lock, flags);
3867    md_wakeup_thread(conf->mddev->thread);
3868}
3869
3870
3871static struct bio *remove_bio_from_retry(struct r5conf *conf)
3872{
3873    struct bio *bi;
3874
3875    bi = conf->retry_read_aligned;
3876    if (bi) {
3877        conf->retry_read_aligned = NULL;
3878        return bi;
3879    }
3880    bi = conf->retry_read_aligned_list;
3881    if(bi) {
3882        conf->retry_read_aligned_list = bi->bi_next;
3883        bi->bi_next = NULL;
3884        /*
3885         * this sets the active strip count to 1 and the processed
3886         * strip count to zero (upper 8 bits)
3887         */
3888        raid5_set_bi_stripes(bi, 1); /* biased count of active stripes */
3889    }
3890
3891    return bi;
3892}
3893
3894
3895/*
3896 * The "raid5_align_endio" should check if the read succeeded and if it
3897 * did, call bio_endio on the original bio (having bio_put the new bio
3898 * first).
3899 * If the read failed..
3900 */
3901static void raid5_align_endio(struct bio *bi, int error)
3902{
3903    struct bio* raid_bi = bi->bi_private;
3904    struct mddev *mddev;
3905    struct r5conf *conf;
3906    int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
3907    struct md_rdev *rdev;
3908
3909    bio_put(bi);
3910
3911    rdev = (void*)raid_bi->bi_next;
3912    raid_bi->bi_next = NULL;
3913    mddev = rdev->mddev;
3914    conf = mddev->private;
3915
3916    rdev_dec_pending(rdev, conf->mddev);
3917
3918    if (!error && uptodate) {
3919        trace_block_bio_complete(bdev_get_queue(raid_bi->bi_bdev),
3920                     raid_bi, 0);
3921        bio_endio(raid_bi, 0);
3922        if (atomic_dec_and_test(&conf->active_aligned_reads))
3923            wake_up(&conf->wait_for_stripe);
3924        return;
3925    }
3926
3927
3928    pr_debug("raid5_align_endio : io error...handing IO for a retry\n");
3929
3930    add_bio_to_retry(raid_bi, conf);
3931}
3932
3933static int bio_fits_rdev(struct bio *bi)
3934{
3935    struct request_queue *q = bdev_get_queue(bi->bi_bdev);
3936
3937    if ((bi->bi_size>>9) > queue_max_sectors(q))
3938        return 0;
3939    blk_recount_segments(q, bi);
3940    if (bi->bi_phys_segments > queue_max_segments(q))
3941        return 0;
3942
3943    if (q->merge_bvec_fn)
3944        /* it's too hard to apply the merge_bvec_fn at this stage,
3945         * just just give up
3946         */
3947        return 0;
3948
3949    return 1;
3950}
3951
3952
3953static int chunk_aligned_read(struct mddev *mddev, struct bio * raid_bio)
3954{
3955    struct r5conf *conf = mddev->private;
3956    int dd_idx;
3957    struct bio* align_bi;
3958    struct md_rdev *rdev;
3959    sector_t end_sector;
3960
3961    if (!in_chunk_boundary(mddev, raid_bio)) {
3962        pr_debug("chunk_aligned_read : non aligned\n");
3963        return 0;
3964    }
3965    /*
3966     * use bio_clone_mddev to make a copy of the bio
3967     */
3968    align_bi = bio_clone_mddev(raid_bio, GFP_NOIO, mddev);
3969    if (!align_bi)
3970        return 0;
3971    /*
3972     * set bi_end_io to a new function, and set bi_private to the
3973     * original bio.
3974     */
3975    align_bi->bi_end_io = raid5_align_endio;
3976    align_bi->bi_private = raid_bio;
3977    /*
3978     * compute position
3979     */
3980    align_bi->bi_sector = raid5_compute_sector(conf, raid_bio->bi_sector,
3981                            0,
3982                            &dd_idx, NULL);
3983
3984    end_sector = align_bi->bi_sector + (align_bi->bi_size >> 9);
3985    rcu_read_lock();
3986    rdev = rcu_dereference(conf->disks[dd_idx].replacement);
3987    if (!rdev || test_bit(Faulty, &rdev->flags) ||
3988        rdev->recovery_offset < end_sector) {
3989        rdev = rcu_dereference(conf->disks[dd_idx].rdev);
3990        if (rdev &&
3991            (test_bit(Faulty, &rdev->flags) ||
3992            !(test_bit(In_sync, &rdev->flags) ||
3993              rdev->recovery_offset >= end_sector)))
3994            rdev = NULL;
3995    }
3996    if (rdev) {
3997        sector_t first_bad;
3998        int bad_sectors;
3999
4000        atomic_inc(&rdev->nr_pending);
4001        rcu_read_unlock();
4002        raid_bio->bi_next = (void*)rdev;
4003        align_bi->bi_bdev = rdev->bdev;
4004        align_bi->bi_flags &= ~(1 << BIO_SEG_VALID);
4005
4006        if (!bio_fits_rdev(align_bi) ||
4007            is_badblock(rdev, align_bi->bi_sector, align_bi->bi_size>>9,
4008                &first_bad, &bad_sectors)) {
4009            /* too big in some way, or has a known bad block */
4010            bio_put(align_bi);
4011            rdev_dec_pending(rdev, mddev);
4012            return 0;
4013        }
4014
4015        /* No reshape active, so we can trust rdev->data_offset */
4016        align_bi->bi_sector += rdev->data_offset;
4017
4018        spin_lock_irq(&conf->device_lock);
4019        wait_event_lock_irq(conf->wait_for_stripe,
4020                    conf->quiesce == 0,
4021                    conf->device_lock);
4022        atomic_inc(&conf->active_aligned_reads);
4023        spin_unlock_irq(&conf->device_lock);
4024
4025        if (mddev->gendisk)
4026            trace_block_bio_remap(bdev_get_queue(align_bi->bi_bdev),
4027                          align_bi, disk_devt(mddev->gendisk),
4028                          raid_bio->bi_sector);
4029        generic_make_request(align_bi);
4030        return 1;
4031    } else {
4032        rcu_read_unlock();
4033        bio_put(align_bi);
4034        return 0;
4035    }
4036}
4037
4038/* __get_priority_stripe - get the next stripe to process
4039 *
4040 * Full stripe writes are allowed to pass preread active stripes up until
4041 * the bypass_threshold is exceeded. In general the bypass_count
4042 * increments when the handle_list is handled before the hold_list; however, it
4043 * will not be incremented when STRIPE_IO_STARTED is sampled set signifying a
4044 * stripe with in flight i/o. The bypass_count will be reset when the
4045 * head of the hold_list has changed, i.e. the head was promoted to the
4046 * handle_list.
4047 */
4048static struct stripe_head *__get_priority_stripe(struct r5conf *conf)
4049{
4050    struct stripe_head *sh;
4051
4052    pr_debug("%s: handle: %s hold: %s full_writes: %d bypass_count: %d\n",
4053          __func__,
4054          list_empty(&conf->handle_list) ? "empty" : "busy",
4055          list_empty(&conf->hold_list) ? "empty" : "busy",
4056          atomic_read(&conf->pending_full_writes), conf->bypass_count);
4057
4058    if (!list_empty(&conf->handle_list)) {
4059        sh = list_entry(conf->handle_list.next, typeof(*sh), lru);
4060
4061        if (list_empty(&conf->hold_list))
4062            conf->bypass_count = 0;
4063        else if (!test_bit(STRIPE_IO_STARTED, &sh->state)) {
4064            if (conf->hold_list.next == conf->last_hold)
4065                conf->bypass_count++;
4066            else {
4067                conf->last_hold = conf->hold_list.next;
4068                conf->bypass_count -= conf->bypass_threshold;
4069                if (conf->bypass_count < 0)
4070                    conf->bypass_count = 0;
4071            }
4072        }
4073    } else if (!list_empty(&conf->hold_list) &&
4074           ((conf->bypass_threshold &&
4075             conf->bypass_count > conf->bypass_threshold) ||
4076            atomic_read(&conf->pending_full_writes) == 0)) {
4077        sh = list_entry(conf->hold_list.next,
4078                typeof(*sh), lru);
4079        conf->bypass_count -= conf->bypass_threshold;
4080        if (conf->bypass_count < 0)
4081            conf->bypass_count = 0;
4082    } else
4083        return NULL;
4084
4085    list_del_init(&sh->lru);
4086    atomic_inc(&sh->count);
4087    BUG_ON(atomic_read(&sh->count) != 1);
4088    return sh;
4089}
4090
4091struct raid5_plug_cb {
4092    struct blk_plug_cb cb;
4093    struct list_head list;
4094};
4095
4096static void raid5_unplug(struct blk_plug_cb *blk_cb, bool from_schedule)
4097{
4098    struct raid5_plug_cb *cb = container_of(
4099        blk_cb, struct raid5_plug_cb, cb);
4100    struct stripe_head *sh;
4101    struct mddev *mddev = cb->cb.data;
4102    struct r5conf *conf = mddev->private;
4103    int cnt = 0;
4104
4105    if (cb->list.next && !list_empty(&cb->list)) {
4106        spin_lock_irq(&conf->device_lock);
4107        while (!list_empty(&cb->list)) {
4108            sh = list_first_entry(&cb->list, struct stripe_head, lru);
4109            list_del_init(&sh->lru);
4110            /*
4111             * avoid race release_stripe_plug() sees
4112             * STRIPE_ON_UNPLUG_LIST clear but the stripe
4113             * is still in our list
4114             */
4115            smp_mb__before_clear_bit();
4116            clear_bit(STRIPE_ON_UNPLUG_LIST, &sh->state);
4117            __release_stripe(conf, sh);
4118            cnt++;
4119        }
4120        spin_unlock_irq(&conf->device_lock);
4121    }
4122    if (mddev->queue)
4123        trace_block_unplug(mddev->queue, cnt, !from_schedule);
4124    kfree(cb);
4125}
4126
4127static void release_stripe_plug(struct mddev *mddev,
4128                struct stripe_head *sh)
4129{
4130    struct blk_plug_cb *blk_cb = blk_check_plugged(
4131        raid5_unplug, mddev,
4132        sizeof(struct raid5_plug_cb));
4133    struct raid5_plug_cb *cb;
4134
4135    if (!blk_cb) {
4136        release_stripe(sh);
4137        return;
4138    }
4139
4140    cb = container_of(blk_cb, struct raid5_plug_cb, cb);
4141
4142    if (cb->list.next == NULL)
4143        INIT_LIST_HEAD(&cb->list);
4144
4145    if (!test_and_set_bit(STRIPE_ON_UNPLUG_LIST, &sh->state))
4146        list_add_tail(&sh->lru, &cb->list);
4147    else
4148        release_stripe(sh);
4149}
4150
4151static void make_discard_request(struct mddev *mddev, struct bio *bi)
4152{
4153    struct r5conf *conf = mddev->private;
4154    sector_t logical_sector, last_sector;
4155    struct stripe_head *sh;
4156    int remaining;
4157    int stripe_sectors;
4158
4159    if (mddev->reshape_position != MaxSector)
4160        /* Skip discard while reshape is happening */
4161        return;
4162
4163    logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4164    last_sector = bi->bi_sector + (bi->bi_size>>9);
4165
4166    bi->bi_next = NULL;
4167    bi->bi_phys_segments = 1; /* over-loaded to count active stripes */
4168
4169    stripe_sectors = conf->chunk_sectors *
4170        (conf->raid_disks - conf->max_degraded);
4171    logical_sector = DIV_ROUND_UP_SECTOR_T(logical_sector,
4172                           stripe_sectors);
4173    sector_div(last_sector, stripe_sectors);
4174
4175    logical_sector *= conf->chunk_sectors;
4176    last_sector *= conf->chunk_sectors;
4177
4178    for (; logical_sector < last_sector;
4179         logical_sector += STRIPE_SECTORS) {
4180        DEFINE_WAIT(w);
4181        int d;
4182    again:
4183        sh = get_active_stripe(conf, logical_sector, 0, 0, 0);
4184        prepare_to_wait(&conf->wait_for_overlap, &w,
4185                TASK_UNINTERRUPTIBLE);
4186        set_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
4187        if (test_bit(STRIPE_SYNCING, &sh->state)) {
4188            release_stripe(sh);
4189            schedule();
4190            goto again;
4191        }
4192        clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
4193        spin_lock_irq(&sh->stripe_lock);
4194        for (d = 0; d < conf->raid_disks; d++) {
4195            if (d == sh->pd_idx || d == sh->qd_idx)
4196                continue;
4197            if (sh->dev[d].towrite || sh->dev[d].toread) {
4198                set_bit(R5_Overlap, &sh->dev[d].flags);
4199                spin_unlock_irq(&sh->stripe_lock);
4200                release_stripe(sh);
4201                schedule();
4202                goto again;
4203            }
4204        }
4205        set_bit(STRIPE_DISCARD, &sh->state);
4206        finish_wait(&conf->wait_for_overlap, &w);
4207        for (d = 0; d < conf->raid_disks; d++) {
4208            if (d == sh->pd_idx || d == sh->qd_idx)
4209                continue;
4210            sh->dev[d].towrite = bi;
4211            set_bit(R5_OVERWRITE, &sh->dev[d].flags);
4212            raid5_inc_bi_active_stripes(bi);
4213        }
4214        spin_unlock_irq(&sh->stripe_lock);
4215        if (conf->mddev->bitmap) {
4216            for (d = 0;
4217                 d < conf->raid_disks - conf->max_degraded;
4218                 d++)
4219                bitmap_startwrite(mddev->bitmap,
4220                          sh->sector,
4221                          STRIPE_SECTORS,
4222                          0);
4223            sh->bm_seq = conf->seq_flush + 1;
4224            set_bit(STRIPE_BIT_DELAY, &sh->state);
4225        }
4226
4227        set_bit(STRIPE_HANDLE, &sh->state);
4228        clear_bit(STRIPE_DELAYED, &sh->state);
4229        if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4230            atomic_inc(&conf->preread_active_stripes);
4231        release_stripe_plug(mddev, sh);
4232    }
4233
4234    remaining = raid5_dec_bi_active_stripes(bi);
4235    if (remaining == 0) {
4236        md_write_end(mddev);
4237        bio_endio(bi, 0);
4238    }
4239}
4240
4241static void make_request(struct mddev *mddev, struct bio * bi)
4242{
4243    struct r5conf *conf = mddev->private;
4244    int dd_idx;
4245    sector_t new_sector;
4246    sector_t logical_sector, last_sector;
4247    struct stripe_head *sh;
4248    const int rw = bio_data_dir(bi);
4249    int remaining;
4250
4251    if (unlikely(bi->bi_rw & REQ_FLUSH)) {
4252        md_flush_request(mddev, bi);
4253        return;
4254    }
4255
4256    md_write_start(mddev, bi);
4257
4258    if (rw == READ &&
4259         mddev->reshape_position == MaxSector &&
4260         chunk_aligned_read(mddev,bi))
4261        return;
4262
4263    if (unlikely(bi->bi_rw & REQ_DISCARD)) {
4264        make_discard_request(mddev, bi);
4265        return;
4266    }
4267
4268    logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4269    last_sector = bi->bi_sector + (bi->bi_size>>9);
4270    bi->bi_next = NULL;
4271    bi->bi_phys_segments = 1; /* over-loaded to count active stripes */
4272
4273    for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
4274        DEFINE_WAIT(w);
4275        int previous;
4276
4277    retry:
4278        previous = 0;
4279        prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
4280        if (unlikely(conf->reshape_progress != MaxSector)) {
4281            /* spinlock is needed as reshape_progress may be
4282             * 64bit on a 32bit platform, and so it might be
4283             * possible to see a half-updated value
4284             * Of course reshape_progress could change after
4285             * the lock is dropped, so once we get a reference
4286             * to the stripe that we think it is, we will have
4287             * to check again.
4288             */
4289            spin_lock_irq(&conf->device_lock);
4290            if (mddev->reshape_backwards
4291                ? logical_sector < conf->reshape_progress
4292                : logical_sector >= conf->reshape_progress) {
4293                previous = 1;
4294            } else {
4295                if (mddev->reshape_backwards
4296                    ? logical_sector < conf->reshape_safe
4297                    : logical_sector >= conf->reshape_safe) {
4298                    spin_unlock_irq(&conf->device_lock);
4299                    schedule();
4300                    goto retry;
4301                }
4302            }
4303            spin_unlock_irq(&conf->device_lock);
4304        }
4305
4306        new_sector = raid5_compute_sector(conf, logical_sector,
4307                          previous,
4308                          &dd_idx, NULL);
4309        pr_debug("raid456: make_request, sector %llu logical %llu\n",
4310            (unsigned long long)new_sector,
4311            (unsigned long long)logical_sector);
4312
4313        sh = get_active_stripe(conf, new_sector, previous,
4314                       (bi->bi_rw&RWA_MASK), 0);
4315        if (sh) {
4316            if (unlikely(previous)) {
4317                /* expansion might have moved on while waiting for a
4318                 * stripe, so we must do the range check again.
4319                 * Expansion could still move past after this
4320                 * test, but as we are holding a reference to
4321                 * 'sh', we know that if that happens,
4322                 * STRIPE_EXPANDING will get set and the expansion
4323                 * won't proceed until we finish with the stripe.
4324                 */
4325                int must_retry = 0;
4326                spin_lock_irq(&conf->device_lock);
4327                if (mddev->reshape_backwards
4328                    ? logical_sector >= conf->reshape_progress
4329                    : logical_sector < conf->reshape_progress)
4330                    /* mismatch, need to try again */
4331                    must_retry = 1;
4332                spin_unlock_irq(&conf->device_lock);
4333                if (must_retry) {
4334                    release_stripe(sh);
4335                    schedule();
4336                    goto retry;
4337                }
4338            }
4339
4340            if (rw == WRITE &&
4341                logical_sector >= mddev->suspend_lo &&
4342                logical_sector < mddev->suspend_hi) {
4343                release_stripe(sh);
4344                /* As the suspend_* range is controlled by
4345                 * userspace, we want an interruptible
4346                 * wait.
4347                 */
4348                flush_signals(current);
4349                prepare_to_wait(&conf->wait_for_overlap,
4350                        &w, TASK_INTERRUPTIBLE);
4351                if (logical_sector >= mddev->suspend_lo &&
4352                    logical_sector < mddev->suspend_hi)
4353                    schedule();
4354                goto retry;
4355            }
4356
4357            if (test_bit(STRIPE_EXPANDING, &sh->state) ||
4358                !add_stripe_bio(sh, bi, dd_idx, rw)) {
4359                /* Stripe is busy expanding or
4360                 * add failed due to overlap. Flush everything
4361                 * and wait a while
4362                 */
4363                md_wakeup_thread(mddev->thread);
4364                release_stripe(sh);
4365                schedule();
4366                goto retry;
4367            }
4368            finish_wait(&conf->wait_for_overlap, &w);
4369            set_bit(STRIPE_HANDLE, &sh->state);
4370            clear_bit(STRIPE_DELAYED, &sh->state);
4371            if ((bi->bi_rw & REQ_SYNC) &&
4372                !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4373                atomic_inc(&conf->preread_active_stripes);
4374            release_stripe_plug(mddev, sh);
4375        } else {
4376            /* cannot get stripe for read-ahead, just give-up */
4377            clear_bit(BIO_UPTODATE, &bi->bi_flags);
4378            finish_wait(&conf->wait_for_overlap, &w);
4379            break;
4380        }
4381    }
4382
4383    remaining = raid5_dec_bi_active_stripes(bi);
4384    if (remaining == 0) {
4385
4386        if ( rw == WRITE )
4387            md_write_end(mddev);
4388
4389        trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
4390                     bi, 0);
4391        bio_endio(bi, 0);
4392    }
4393}
4394
4395static sector_t raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks);
4396
4397static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *skipped)
4398{
4399    /* reshaping is quite different to recovery/resync so it is
4400     * handled quite separately ... here.
4401     *
4402     * On each call to sync_request, we gather one chunk worth of
4403     * destination stripes and flag them as expanding.
4404     * Then we find all the source stripes and request reads.
4405     * As the reads complete, handle_stripe will copy the data
4406     * into the destination stripe and release that stripe.
4407     */
4408    struct r5conf *conf = mddev->private;
4409    struct stripe_head *sh;
4410    sector_t first_sector, last_sector;
4411    int raid_disks = conf->previous_raid_disks;
4412    int data_disks = raid_disks - conf->max_degraded;
4413    int new_data_disks = conf->raid_disks - conf->max_degraded;
4414    int i;
4415    int dd_idx;
4416    sector_t writepos, readpos, safepos;
4417    sector_t stripe_addr;
4418    int reshape_sectors;
4419    struct list_head stripes;
4420
4421    if (sector_nr == 0) {
4422        /* If restarting in the middle, skip the initial sectors */
4423        if (mddev->reshape_backwards &&
4424            conf->reshape_progress < raid5_size(mddev, 0, 0)) {
4425            sector_nr = raid5_size(mddev, 0, 0)
4426                - conf->reshape_progress;
4427        } else if (!mddev->reshape_backwards &&
4428               conf->reshape_progress > 0)
4429            sector_nr = conf->reshape_progress;
4430        sector_div(sector_nr, new_data_disks);
4431        if (sector_nr) {
4432            mddev->curr_resync_completed = sector_nr;
4433            sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4434            *skipped = 1;
4435            return sector_nr;
4436        }
4437    }
4438
4439    /* We need to process a full chunk at a time.
4440     * If old and new chunk sizes differ, we need to process the
4441     * largest of these
4442     */
4443    if (mddev->new_chunk_sectors > mddev->chunk_sectors)
4444        reshape_sectors = mddev->new_chunk_sectors;
4445    else
4446        reshape_sectors = mddev->chunk_sectors;
4447
4448    /* We update the metadata at least every 10 seconds, or when
4449     * the data about to be copied would over-write the source of
4450     * the data at the front of the range. i.e. one new_stripe
4451     * along from reshape_progress new_maps to after where
4452     * reshape_safe old_maps to
4453     */
4454    writepos = conf->reshape_progress;
4455    sector_div(writepos, new_data_disks);
4456    readpos = conf->reshape_progress;
4457    sector_div(readpos, data_disks);
4458    safepos = conf->reshape_safe;
4459    sector_div(safepos, data_disks);
4460    if (mddev->reshape_backwards) {
4461        writepos -= min_t(sector_t, reshape_sectors, writepos);
4462        readpos += reshape_sectors;
4463        safepos += reshape_sectors;
4464    } else {
4465        writepos += reshape_sectors;
4466        readpos -= min_t(sector_t, reshape_sectors, readpos);
4467        safepos -= min_t(sector_t, reshape_sectors, safepos);
4468    }
4469
4470    /* Having calculated the 'writepos' possibly use it
4471     * to set 'stripe_addr' which is where we will write to.
4472     */
4473    if (mddev->reshape_backwards) {
4474        BUG_ON(conf->reshape_progress == 0);
4475        stripe_addr = writepos;
4476        BUG_ON((mddev->dev_sectors &
4477            ~((sector_t)reshape_sectors - 1))
4478               - reshape_sectors - stripe_addr
4479               != sector_nr);
4480    } else {
4481        BUG_ON(writepos != sector_nr + reshape_sectors);
4482        stripe_addr = sector_nr;
4483    }
4484
4485    /* 'writepos' is the most advanced device address we might write.
4486     * 'readpos' is the least advanced device address we might read.
4487     * 'safepos' is the least address recorded in the metadata as having
4488     * been reshaped.
4489     * If there is a min_offset_diff, these are adjusted either by
4490     * increasing the safepos/readpos if diff is negative, or
4491     * increasing writepos if diff is positive.
4492     * If 'readpos' is then behind 'writepos', there is no way that we can
4493     * ensure safety in the face of a crash - that must be done by userspace
4494     * making a backup of the data. So in that case there is no particular
4495     * rush to update metadata.
4496     * Otherwise if 'safepos' is behind 'writepos', then we really need to
4497     * update the metadata to advance 'safepos' to match 'readpos' so that
4498     * we can be safe in the event of a crash.
4499     * So we insist on updating metadata if safepos is behind writepos and
4500     * readpos is beyond writepos.
4501     * In any case, update the metadata every 10 seconds.
4502     * Maybe that number should be configurable, but I'm not sure it is
4503     * worth it.... maybe it could be a multiple of safemode_delay???
4504     */
4505    if (conf->min_offset_diff < 0) {
4506        safepos += -conf->min_offset_diff;
4507        readpos += -conf->min_offset_diff;
4508    } else
4509        writepos += conf->min_offset_diff;
4510
4511    if ((mddev->reshape_backwards
4512         ? (safepos > writepos && readpos < writepos)
4513         : (safepos < writepos && readpos > writepos)) ||
4514        time_after(jiffies, conf->reshape_checkpoint + 10*HZ)) {
4515        /* Cannot proceed until we've updated the superblock... */
4516        wait_event(conf->wait_for_overlap,
4517               atomic_read(&conf->reshape_stripes)==0);
4518        mddev->reshape_position = conf->reshape_progress;
4519        mddev->curr_resync_completed = sector_nr;
4520        conf->reshape_checkpoint = jiffies;
4521        set_bit(MD_CHANGE_DEVS, &mddev->flags);
4522        md_wakeup_thread(mddev->thread);
4523        wait_event(mddev->sb_wait, mddev->flags == 0 ||
4524               kthread_should_stop());
4525        spin_lock_irq(&conf->device_lock);
4526        conf->reshape_safe = mddev->reshape_position;
4527        spin_unlock_irq(&conf->device_lock);
4528        wake_up(&conf->wait_for_overlap);
4529        sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4530    }
4531
4532    INIT_LIST_HEAD(&stripes);
4533    for (i = 0; i < reshape_sectors; i += STRIPE_SECTORS) {
4534        int j;
4535        int skipped_disk = 0;
4536        sh = get_active_stripe(conf, stripe_addr+i, 0, 0, 1);
4537        set_bit(STRIPE_EXPANDING, &sh->state);
4538        atomic_inc(&conf->reshape_stripes);
4539        /* If any of this stripe is beyond the end of the old
4540         * array, then we need to zero those blocks
4541         */
4542        for (j=sh->disks; j--;) {
4543            sector_t s;
4544            if (j == sh->pd_idx)
4545                continue;
4546            if (conf->level == 6 &&
4547                j == sh->qd_idx)
4548                continue;
4549            s = compute_blocknr(sh, j, 0);
4550            if (s < raid5_size(mddev, 0, 0)) {
4551                skipped_disk = 1;
4552                continue;
4553            }
4554            memset(page_address(sh->dev[j].page), 0, STRIPE_SIZE);
4555            set_bit(R5_Expanded, &sh->dev[j].flags);
4556            set_bit(R5_UPTODATE, &sh->dev[j].flags);
4557        }
4558        if (!skipped_disk) {
4559            set_bit(STRIPE_EXPAND_READY, &sh->state);
4560            set_bit(STRIPE_HANDLE, &sh->state);
4561        }
4562        list_add(&sh->lru, &stripes);
4563    }
4564    spin_lock_irq(&conf->device_lock);
4565    if (mddev->reshape_backwards)
4566        conf->reshape_progress -= reshape_sectors * new_data_disks;
4567    else
4568        conf->reshape_progress += reshape_sectors * new_data_disks;
4569    spin_unlock_irq(&conf->device_lock);
4570    /* Ok, those stripe are ready. We can start scheduling
4571     * reads on the source stripes.
4572     * The source stripes are determined by mapping the first and last
4573     * block on the destination stripes.
4574     */
4575    first_sector =
4576        raid5_compute_sector(conf, stripe_addr*(new_data_disks),
4577                     1, &dd_idx, NULL);
4578    last_sector =
4579        raid5_compute_sector(conf, ((stripe_addr+reshape_sectors)
4580                        * new_data_disks - 1),
4581                     1, &dd_idx, NULL);
4582    if (last_sector >= mddev->dev_sectors)
4583        last_sector = mddev->dev_sectors - 1;
4584    while (first_sector <= last_sector) {
4585        sh = get_active_stripe(conf, first_sector, 1, 0, 1);
4586        set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
4587        set_bit(STRIPE_HANDLE, &sh->state);
4588        release_stripe(sh);
4589        first_sector += STRIPE_SECTORS;
4590    }
4591    /* Now that the sources are clearly marked, we can release
4592     * the destination stripes
4593     */
4594    while (!list_empty(&stripes)) {
4595        sh = list_entry(stripes.next, struct stripe_head, lru);
4596        list_del_init(&sh->lru);
4597        release_stripe(sh);
4598    }
4599    /* If this takes us to the resync_max point where we have to pause,
4600     * then we need to write out the superblock.
4601     */
4602    sector_nr += reshape_sectors;
4603    if ((sector_nr - mddev->curr_resync_completed) * 2
4604        >= mddev->resync_max - mddev->curr_resync_completed) {
4605        /* Cannot proceed until we've updated the superblock... */
4606        wait_event(conf->wait_for_overlap,
4607               atomic_read(&conf->reshape_stripes) == 0);
4608        mddev->reshape_position = conf->reshape_progress;
4609        mddev->curr_resync_completed = sector_nr;
4610        conf->reshape_checkpoint = jiffies;
4611        set_bit(MD_CHANGE_DEVS, &mddev->flags);
4612        md_wakeup_thread(mddev->thread);
4613        wait_event(mddev->sb_wait,
4614               !test_bit(MD_CHANGE_DEVS, &mddev->flags)
4615               || kthread_should_stop());
4616        spin_lock_irq(&conf->device_lock);
4617        conf->reshape_safe = mddev->reshape_position;
4618        spin_unlock_irq(&conf->device_lock);
4619        wake_up(&conf->wait_for_overlap);
4620        sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4621    }
4622    return reshape_sectors;
4623}
4624
4625/* FIXME go_faster isn't used */
4626static inline sector_t sync_request(struct mddev *mddev, sector_t sector_nr, int *skipped, int go_faster)
4627{
4628    struct r5conf *conf = mddev->private;
4629    struct stripe_head *sh;
4630    sector_t max_sector = mddev->dev_sectors;
4631    sector_t sync_blocks;
4632    int still_degraded = 0;
4633    int i;
4634
4635    if (sector_nr >= max_sector) {
4636        /* just being told to finish up .. nothing much to do */
4637
4638        if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
4639            end_reshape(conf);
4640            return 0;
4641        }
4642
4643        if (mddev->curr_resync < max_sector) /* aborted */
4644            bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
4645                    &sync_blocks, 1);
4646        else /* completed sync */
4647            conf->fullsync = 0;
4648        bitmap_close_sync(mddev->bitmap);
4649
4650        return 0;
4651    }
4652
4653    /* Allow raid5_quiesce to complete */
4654    wait_event(conf->wait_for_overlap, conf->quiesce != 2);
4655
4656    if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
4657        return reshape_request(mddev, sector_nr, skipped);
4658
4659    /* No need to check resync_max as we never do more than one
4660     * stripe, and as resync_max will always be on a chunk boundary,
4661     * if the check in md_do_sync didn't fire, there is no chance
4662     * of overstepping resync_max here
4663     */
4664
4665    /* if there is too many failed drives and we are trying
4666     * to resync, then assert that we are finished, because there is
4667     * nothing we can do.
4668     */
4669    if (mddev->degraded >= conf->max_degraded &&
4670        test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
4671        sector_t rv = mddev->dev_sectors - sector_nr;
4672        *skipped = 1;
4673        return rv;
4674    }
4675    if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
4676        !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
4677        !conf->fullsync && sync_blocks >= STRIPE_SECTORS) {
4678        /* we can skip this block, and probably more */
4679        sync_blocks /= STRIPE_SECTORS;
4680        *skipped = 1;
4681        return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
4682    }
4683
4684    bitmap_cond_end_sync(mddev->bitmap, sector_nr);
4685
4686    sh = get_active_stripe(conf, sector_nr, 0, 1, 0);
4687    if (sh == NULL) {
4688        sh = get_active_stripe(conf, sector_nr, 0, 0, 0);
4689        /* make sure we don't swamp the stripe cache if someone else
4690         * is trying to get access
4691         */
4692        schedule_timeout_uninterruptible(1);
4693    }
4694    /* Need to check if array will still be degraded after recovery/resync
4695     * We don't need to check the 'failed' flag as when that gets set,
4696     * recovery aborts.
4697     */
4698    for (i = 0; i < conf->raid_disks; i++)
4699        if (conf->disks[i].rdev == NULL)
4700            still_degraded = 1;
4701
4702    bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
4703
4704    set_bit(STRIPE_SYNC_REQUESTED, &sh->state);
4705
4706    handle_stripe(sh);
4707    release_stripe(sh);
4708
4709    return STRIPE_SECTORS;
4710}
4711
4712static int retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
4713{
4714    /* We may not be able to submit a whole bio at once as there
4715     * may not be enough stripe_heads available.
4716     * We cannot pre-allocate enough stripe_heads as we may need
4717     * more than exist in the cache (if we allow ever large chunks).
4718     * So we do one stripe head at a time and record in
4719     * ->bi_hw_segments how many have been done.
4720     *
4721     * We *know* that this entire raid_bio is in one chunk, so
4722     * it will be only one 'dd_idx' and only need one call to raid5_compute_sector.
4723     */
4724    struct stripe_head *sh;
4725    int dd_idx;
4726    sector_t sector, logical_sector, last_sector;
4727    int scnt = 0;
4728    int remaining;
4729    int handled = 0;
4730
4731    logical_sector = raid_bio->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4732    sector = raid5_compute_sector(conf, logical_sector,
4733                      0, &dd_idx, NULL);
4734    last_sector = raid_bio->bi_sector + (raid_bio->bi_size>>9);
4735
4736    for (; logical_sector < last_sector;
4737         logical_sector += STRIPE_SECTORS,
4738             sector += STRIPE_SECTORS,
4739             scnt++) {
4740
4741        if (scnt < raid5_bi_processed_stripes(raid_bio))
4742            /* already done this stripe */
4743            continue;
4744
4745        sh = get_active_stripe(conf, sector, 0, 1, 0);
4746
4747        if (!sh) {
4748            /* failed to get a stripe - must wait */
4749            raid5_set_bi_processed_stripes(raid_bio, scnt);
4750            conf->retry_read_aligned = raid_bio;
4751            return handled;
4752        }
4753
4754        if (!add_stripe_bio(sh, raid_bio, dd_idx, 0)) {
4755            release_stripe(sh);
4756            raid5_set_bi_processed_stripes(raid_bio, scnt);
4757            conf->retry_read_aligned = raid_bio;
4758            return handled;
4759        }
4760
4761        set_bit(R5_ReadNoMerge, &sh->dev[dd_idx].flags);
4762        handle_stripe(sh);
4763        release_stripe(sh);
4764        handled++;
4765    }
4766    remaining = raid5_dec_bi_active_stripes(raid_bio);
4767    if (remaining == 0) {
4768        trace_block_bio_complete(bdev_get_queue(raid_bio->bi_bdev),
4769                     raid_bio, 0);
4770        bio_endio(raid_bio, 0);
4771    }
4772    if (atomic_dec_and_test(&conf->active_aligned_reads))
4773        wake_up(&conf->wait_for_stripe);
4774    return handled;
4775}
4776
4777#define MAX_STRIPE_BATCH 8
4778static int handle_active_stripes(struct r5conf *conf)
4779{
4780    struct stripe_head *batch[MAX_STRIPE_BATCH], *sh;
4781    int i, batch_size = 0;
4782
4783    while (batch_size < MAX_STRIPE_BATCH &&
4784            (sh = __get_priority_stripe(conf)) != NULL)
4785        batch[batch_size++] = sh;
4786
4787    if (batch_size == 0)
4788        return batch_size;
4789    spin_unlock_irq(&conf->device_lock);
4790
4791    for (i = 0; i < batch_size; i++)
4792        handle_stripe(batch[i]);
4793
4794    cond_resched();
4795
4796    spin_lock_irq(&conf->device_lock);
4797    for (i = 0; i < batch_size; i++)
4798        __release_stripe(conf, batch[i]);
4799    return batch_size;
4800}
4801
4802/*
4803 * This is our raid5 kernel thread.
4804 *
4805 * We scan the hash table for stripes which can be handled now.
4806 * During the scan, completed stripes are saved for us by the interrupt
4807 * handler, so that they will not have to wait for our next wakeup.
4808 */
4809static void raid5d(struct md_thread *thread)
4810{
4811    struct mddev *mddev = thread->mddev;
4812    struct r5conf *conf = mddev->private;
4813    int handled;
4814    struct blk_plug plug;
4815
4816    pr_debug("+++ raid5d active\n");
4817
4818    md_check_recovery(mddev);
4819
4820    blk_start_plug(&plug);
4821    handled = 0;
4822    spin_lock_irq(&conf->device_lock);
4823    while (1) {
4824        struct bio *bio;
4825        int batch_size;
4826
4827        if (
4828            !list_empty(&conf->bitmap_list)) {
4829            /* Now is a good time to flush some bitmap updates */
4830            conf->seq_flush++;
4831            spin_unlock_irq(&conf->device_lock);
4832            bitmap_unplug(mddev->bitmap);
4833            spin_lock_irq(&conf->device_lock);
4834            conf->seq_write = conf->seq_flush;
4835            activate_bit_delay(conf);
4836        }
4837        raid5_activate_delayed(conf);
4838
4839        while ((bio = remove_bio_from_retry(conf))) {
4840            int ok;
4841            spin_unlock_irq(&conf->device_lock);
4842            ok = retry_aligned_read(conf, bio);
4843            spin_lock_irq(&conf->device_lock);
4844            if (!ok)
4845                break;
4846            handled++;
4847        }
4848
4849        batch_size = handle_active_stripes(conf);
4850        if (!batch_size)
4851            break;
4852        handled += batch_size;
4853
4854        if (mddev->flags & ~(1<<MD_CHANGE_PENDING)) {
4855            spin_unlock_irq(&conf->device_lock);
4856            md_check_recovery(mddev);
4857            spin_lock_irq(&conf->device_lock);
4858        }
4859    }
4860    pr_debug("%d stripes handled\n", handled);
4861
4862    spin_unlock_irq(&conf->device_lock);
4863
4864    async_tx_issue_pending_all();
4865    blk_finish_plug(&plug);
4866
4867    pr_debug("--- raid5d inactive\n");
4868}
4869
4870static ssize_t
4871raid5_show_stripe_cache_size(struct mddev *mddev, char *page)
4872{
4873    struct r5conf *conf = mddev->private;
4874    if (conf)
4875        return sprintf(page, "%d\n", conf->max_nr_stripes);
4876    else
4877        return 0;
4878}
4879
4880int
4881raid5_set_cache_size(struct mddev *mddev, int size)
4882{
4883    struct r5conf *conf = mddev->private;
4884    int err;
4885
4886    if (size <= 16 || size > 32768)
4887        return -EINVAL;
4888    while (size < conf->max_nr_stripes) {
4889        if (drop_one_stripe(conf))
4890            conf->max_nr_stripes--;
4891        else
4892            break;
4893    }
4894    err = md_allow_write(mddev);
4895    if (err)
4896        return err;
4897    while (size > conf->max_nr_stripes) {
4898        if (grow_one_stripe(conf))
4899            conf->max_nr_stripes++;
4900        else break;
4901    }
4902    return 0;
4903}
4904EXPORT_SYMBOL(raid5_set_cache_size);
4905
4906static ssize_t
4907raid5_store_stripe_cache_size(struct mddev *mddev, const char *page, size_t len)
4908{
4909    struct r5conf *conf = mddev->private;
4910    unsigned long new;
4911    int err;
4912
4913    if (len >= PAGE_SIZE)
4914        return -EINVAL;
4915    if (!conf)
4916        return -ENODEV;
4917
4918    if (strict_strtoul(page, 10, &new))
4919        return -EINVAL;
4920    err = raid5_set_cache_size(mddev, new);
4921    if (err)
4922        return err;
4923    return len;
4924}
4925
4926static struct md_sysfs_entry
4927raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
4928                raid5_show_stripe_cache_size,
4929                raid5_store_stripe_cache_size);
4930
4931static ssize_t
4932raid5_show_preread_threshold(struct mddev *mddev, char *page)
4933{
4934    struct r5conf *conf = mddev->private;
4935    if (conf)
4936        return sprintf(page, "%d\n", conf->bypass_threshold);
4937    else
4938        return 0;
4939}
4940
4941static ssize_t
4942raid5_store_preread_threshold(struct mddev *mddev, const char *page, size_t len)
4943{
4944    struct r5conf *conf = mddev->private;
4945    unsigned long new;
4946    if (len >= PAGE_SIZE)
4947        return -EINVAL;
4948    if (!conf)
4949        return -ENODEV;
4950
4951    if (strict_strtoul(page, 10, &new))
4952        return -EINVAL;
4953    if (new > conf->max_nr_stripes)
4954        return -EINVAL;
4955    conf->bypass_threshold = new;
4956    return len;
4957}
4958
4959static struct md_sysfs_entry
4960raid5_preread_bypass_threshold = __ATTR(preread_bypass_threshold,
4961                    S_IRUGO | S_IWUSR,
4962                    raid5_show_preread_threshold,
4963                    raid5_store_preread_threshold);
4964
4965static ssize_t
4966stripe_cache_active_show(struct mddev *mddev, char *page)
4967{
4968    struct r5conf *conf = mddev->private;
4969    if (conf)
4970        return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
4971    else
4972        return 0;
4973}
4974
4975static struct md_sysfs_entry
4976raid5_stripecache_active = __ATTR_RO(stripe_cache_active);
4977
4978static struct attribute *raid5_attrs[] = {
4979    &raid5_stripecache_size.attr,
4980    &raid5_stripecache_active.attr,
4981    &raid5_preread_bypass_threshold.attr,
4982    NULL,
4983};
4984static struct attribute_group raid5_attrs_group = {
4985    .name = NULL,
4986    .attrs = raid5_attrs,
4987};
4988
4989static sector_t
4990raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks)
4991{
4992    struct r5conf *conf = mddev->private;
4993
4994    if (!sectors)
4995        sectors = mddev->dev_sectors;
4996    if (!raid_disks)
4997        /* size is defined by the smallest of previous and new size */
4998        raid_disks = min(conf->raid_disks, conf->previous_raid_disks);
4999
5000    sectors &= ~((sector_t)mddev->chunk_sectors - 1);
5001    sectors &= ~((sector_t)mddev->new_chunk_sectors - 1);
5002    return sectors * (raid_disks - conf->max_degraded);
5003}
5004
5005static void raid5_free_percpu(struct r5conf *conf)
5006{
5007    struct raid5_percpu *percpu;
5008    unsigned long cpu;
5009
5010    if (!conf->percpu)
5011        return;
5012
5013    get_online_cpus();
5014    for_each_possible_cpu(cpu) {
5015        percpu = per_cpu_ptr(conf->percpu, cpu);
5016        safe_put_page(percpu->spare_page);
5017        kfree(percpu->scribble);
5018    }
5019#ifdef CONFIG_HOTPLUG_CPU
5020    unregister_cpu_notifier(&conf->cpu_notify);
5021#endif
5022    put_online_cpus();
5023
5024    free_percpu(conf->percpu);
5025}
5026
5027static void free_conf(struct r5conf *conf)
5028{
5029    shrink_stripes(conf);
5030    raid5_free_percpu(conf);
5031    kfree(conf->disks);
5032    kfree(conf->stripe_hashtbl);
5033    kfree(conf);
5034}
5035
5036#ifdef CONFIG_HOTPLUG_CPU
5037static int raid456_cpu_notify(struct notifier_block *nfb, unsigned long action,
5038                  void *hcpu)
5039{
5040    struct r5conf *conf = container_of(nfb, struct r5conf, cpu_notify);
5041    long cpu = (long)hcpu;
5042    struct raid5_percpu *percpu = per_cpu_ptr(conf->percpu, cpu);
5043
5044    switch (action) {
5045    case CPU_UP_PREPARE:
5046    case CPU_UP_PREPARE_FROZEN:
5047        if (conf->level == 6 && !percpu->spare_page)
5048            percpu->spare_page = alloc_page(GFP_KERNEL);
5049        if (!percpu->scribble)
5050            percpu->scribble = kmalloc(conf->scribble_len, GFP_KERNEL);
5051
5052        if (!percpu->scribble ||
5053            (conf->level == 6 && !percpu->spare_page)) {
5054            safe_put_page(percpu->spare_page);
5055            kfree(percpu->scribble);
5056            pr_err("%s: failed memory allocation for cpu%ld\n",
5057                   __func__, cpu);
5058            return notifier_from_errno(-ENOMEM);
5059        }
5060        break;
5061    case CPU_DEAD:
5062    case CPU_DEAD_FROZEN:
5063        safe_put_page(percpu->spare_page);
5064        kfree(percpu->scribble);
5065        percpu->spare_page = NULL;
5066        percpu->scribble = NULL;
5067        break;
5068    default:
5069        break;
5070    }
5071    return NOTIFY_OK;
5072}
5073#endif
5074
5075static int raid5_alloc_percpu(struct r5conf *conf)
5076{
5077    unsigned long cpu;
5078    struct page *spare_page;
5079    struct raid5_percpu __percpu *allcpus;
5080    void *scribble;
5081    int err;
5082
5083    allcpus = alloc_percpu(struct raid5_percpu);
5084    if (!allcpus)
5085        return -ENOMEM;
5086    conf->percpu = allcpus;
5087
5088    get_online_cpus();
5089    err = 0;
5090    for_each_present_cpu(cpu) {
5091        if (conf->level == 6) {
5092            spare_page = alloc_page(GFP_KERNEL);
5093            if (!spare_page) {
5094                err = -ENOMEM;
5095                break;
5096            }
5097            per_cpu_ptr(conf->percpu, cpu)->spare_page = spare_page;
5098        }
5099        scribble = kmalloc(conf->scribble_len, GFP_KERNEL);
5100        if (!scribble) {
5101            err = -ENOMEM;
5102            break;
5103        }
5104        per_cpu_ptr(conf->percpu, cpu)->scribble = scribble;
5105    }
5106#ifdef CONFIG_HOTPLUG_CPU
5107    conf->cpu_notify.notifier_call = raid456_cpu_notify;
5108    conf->cpu_notify.priority = 0;
5109    if (err == 0)
5110        err = register_cpu_notifier(&conf->cpu_notify);
5111#endif
5112    put_online_cpus();
5113
5114    return err;
5115}
5116
5117static struct r5conf *setup_conf(struct mddev *mddev)
5118{
5119    struct r5conf *conf;
5120    int raid_disk, memory, max_disks;
5121    struct md_rdev *rdev;
5122    struct disk_info *disk;
5123    char pers_name[6];
5124
5125    if (mddev->new_level != 5
5126        && mddev->new_level != 4
5127        && mddev->new_level != 6) {
5128        printk(KERN_ERR "md/raid:%s: raid level not set to 4/5/6 (%d)\n",
5129               mdname(mddev), mddev->new_level);
5130        return ERR_PTR(-EIO);
5131    }
5132    if ((mddev->new_level == 5
5133         && !algorithm_valid_raid5(mddev->new_layout)) ||
5134        (mddev->new_level == 6
5135         && !algorithm_valid_raid6(mddev->new_layout))) {
5136        printk(KERN_ERR "md/raid:%s: layout %d not supported\n",
5137               mdname(mddev), mddev->new_layout);
5138        return ERR_PTR(-EIO);
5139    }
5140    if (mddev->new_level == 6 && mddev->raid_disks < 4) {
5141        printk(KERN_ERR "md/raid:%s: not enough configured devices (%d, minimum 4)\n",
5142               mdname(mddev), mddev->raid_disks);
5143        return ERR_PTR(-EINVAL);
5144    }
5145
5146    if (!mddev->new_chunk_sectors ||
5147        (mddev->new_chunk_sectors << 9) % PAGE_SIZE ||
5148        !is_power_of_2(mddev->new_chunk_sectors)) {
5149        printk(KERN_ERR "md/raid:%s: invalid chunk size %d\n",
5150               mdname(mddev), mddev->new_chunk_sectors << 9);
5151        return ERR_PTR(-EINVAL);
5152    }
5153
5154    conf = kzalloc(sizeof(struct r5conf), GFP_KERNEL);
5155    if (conf == NULL)
5156        goto abort;
5157    spin_lock_init(&conf->device_lock);
5158    init_waitqueue_head(&conf->wait_for_stripe);
5159    init_waitqueue_head(&conf->wait_for_overlap);
5160    INIT_LIST_HEAD(&conf->handle_list);
5161    INIT_LIST_HEAD(&conf->hold_list);
5162    INIT_LIST_HEAD(&conf->delayed_list);
5163    INIT_LIST_HEAD(&conf->bitmap_list);
5164    INIT_LIST_HEAD(&conf->inactive_list);
5165    atomic_set(&conf->active_stripes, 0);
5166    atomic_set(&conf->preread_active_stripes, 0);
5167    atomic_set(&conf->active_aligned_reads, 0);
5168    conf->bypass_threshold = BYPASS_THRESHOLD;
5169    conf->recovery_disabled = mddev->recovery_disabled - 1;
5170
5171    conf->raid_disks = mddev->raid_disks;
5172    if (mddev->reshape_position == MaxSector)
5173        conf->previous_raid_disks = mddev->raid_disks;
5174    else
5175        conf->previous_raid_disks = mddev->raid_disks - mddev->delta_disks;
5176    max_disks = max(conf->raid_disks, conf->previous_raid_disks);
5177    conf->scribble_len = scribble_len(max_disks);
5178
5179    conf->disks = kzalloc(max_disks * sizeof(struct disk_info),
5180                  GFP_KERNEL);
5181    if (!conf->disks)
5182        goto abort;
5183
5184    conf->mddev = mddev;
5185
5186    if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)
5187        goto abort;
5188
5189    conf->level = mddev->new_level;
5190    if (raid5_alloc_percpu(conf) != 0)
5191        goto abort;
5192
5193    pr_debug("raid456: run(%s) called.\n", mdname(mddev));
5194
5195    rdev_for_each(rdev, mddev) {
5196        raid_disk = rdev->raid_disk;
5197        if (raid_disk >= max_disks
5198            || raid_disk < 0)
5199            continue;
5200        disk = conf->disks + raid_disk;
5201
5202        if (test_bit(Replacement, &rdev->flags)) {
5203            if (disk->replacement)
5204                goto abort;
5205            disk->replacement = rdev;
5206        } else {
5207            if (disk->rdev)
5208                goto abort;
5209            disk->rdev = rdev;
5210        }
5211
5212        if (test_bit(In_sync, &rdev->flags)) {
5213            char b[BDEVNAME_SIZE];
5214            printk(KERN_INFO "md/raid:%s: device %s operational as raid"
5215                   " disk %d\n",
5216                   mdname(mddev), bdevname(rdev->bdev, b), raid_disk);
5217        } else if (rdev->saved_raid_disk != raid_disk)
5218            /* Cannot rely on bitmap to complete recovery */
5219            conf->fullsync = 1;
5220    }
5221
5222    conf->chunk_sectors = mddev->new_chunk_sectors;
5223    conf->level = mddev->new_level;
5224    if (conf->level == 6)
5225        conf->max_degraded = 2;
5226    else
5227        conf->max_degraded = 1;
5228    conf->algorithm = mddev->new_layout;
5229    conf->max_nr_stripes = NR_STRIPES;
5230    conf->reshape_progress = mddev->reshape_position;
5231    if (conf->reshape_progress != MaxSector) {
5232        conf->prev_chunk_sectors = mddev->chunk_sectors;
5233        conf->prev_algo = mddev->layout;
5234    }
5235
5236    memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +
5237         max_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
5238    if (grow_stripes(conf, conf->max_nr_stripes)) {
5239        printk(KERN_ERR
5240               "md/raid:%s: couldn't allocate %dkB for buffers\n",
5241               mdname(mddev), memory);
5242        goto abort;
5243    } else
5244        printk(KERN_INFO "md/raid:%s: allocated %dkB\n",
5245               mdname(mddev), memory);
5246
5247    sprintf(pers_name, "raid%d", mddev->new_level);
5248    conf->thread = md_register_thread(raid5d, mddev, pers_name);
5249    if (!conf->thread) {
5250        printk(KERN_ERR
5251               "md/raid:%s: couldn't allocate thread.\n",
5252               mdname(mddev));
5253        goto abort;
5254    }
5255
5256    return conf;
5257
5258 abort:
5259    if (conf) {
5260        free_conf(conf);
5261        return ERR_PTR(-EIO);
5262    } else
5263        return ERR_PTR(-ENOMEM);
5264}
5265
5266
5267static int only_parity(int raid_disk, int algo, int raid_disks, int max_degraded)
5268{
5269    switch (algo) {
5270    case ALGORITHM_PARITY_0:
5271        if (raid_disk < max_degraded)
5272            return 1;
5273        break;
5274    case ALGORITHM_PARITY_N:
5275        if (raid_disk >= raid_disks - max_degraded)
5276            return 1;
5277        break;
5278    case ALGORITHM_PARITY_0_6:
5279        if (raid_disk == 0 ||
5280            raid_disk == raid_disks - 1)
5281            return 1;
5282        break;
5283    case ALGORITHM_LEFT_ASYMMETRIC_6:
5284    case ALGORITHM_RIGHT_ASYMMETRIC_6:
5285    case ALGORITHM_LEFT_SYMMETRIC_6:
5286    case ALGORITHM_RIGHT_SYMMETRIC_6:
5287        if (raid_disk == raid_disks - 1)
5288            return 1;
5289    }
5290    return 0;
5291}
5292
5293static int run(struct mddev *mddev)
5294{
5295    struct r5conf *conf;
5296    int working_disks = 0;
5297    int dirty_parity_disks = 0;
5298    struct md_rdev *rdev;
5299    sector_t reshape_offset = 0;
5300    int i;
5301    long long min_offset_diff = 0;
5302    int first = 1;
5303
5304    if (mddev->recovery_cp != MaxSector)
5305        printk(KERN_NOTICE "md/raid:%s: not clean"
5306               " -- starting background reconstruction\n",
5307               mdname(mddev));
5308
5309    rdev_for_each(rdev, mddev) {
5310        long long diff;
5311        if (rdev->raid_disk < 0)
5312            continue;
5313        diff = (rdev->new_data_offset - rdev->data_offset);
5314        if (first) {
5315            min_offset_diff = diff;
5316            first = 0;
5317        } else if (mddev->reshape_backwards &&
5318             diff < min_offset_diff)
5319            min_offset_diff = diff;
5320        else if (!mddev->reshape_backwards &&
5321             diff > min_offset_diff)
5322            min_offset_diff = diff;
5323    }
5324
5325    if (mddev->reshape_position != MaxSector) {
5326        /* Check that we can continue the reshape.
5327         * Difficulties arise if the stripe we would write to
5328         * next is at or after the stripe we would read from next.
5329         * For a reshape that changes the number of devices, this
5330         * is only possible for a very short time, and mdadm makes
5331         * sure that time appears to have past before assembling
5332         * the array. So we fail if that time hasn't passed.
5333         * For a reshape that keeps the number of devices the same
5334         * mdadm must be monitoring the reshape can keeping the
5335         * critical areas read-only and backed up. It will start
5336         * the array in read-only mode, so we check for that.
5337         */
5338        sector_t here_new, here_old;
5339        int old_disks;
5340