Root/drivers/md/dm.c

1/*
2 * Copyright (C) 2001, 2002 Sistina Software (UK) Limited.
3 * Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
4 *
5 * This file is released under the GPL.
6 */
7
8#include "dm.h"
9#include "dm-uevent.h"
10
11#include <linux/init.h>
12#include <linux/module.h>
13#include <linux/mutex.h>
14#include <linux/moduleparam.h>
15#include <linux/blkpg.h>
16#include <linux/bio.h>
17#include <linux/mempool.h>
18#include <linux/slab.h>
19#include <linux/idr.h>
20#include <linux/hdreg.h>
21#include <linux/delay.h>
22
23#include <trace/events/block.h>
24
25#define DM_MSG_PREFIX "core"
26
27#ifdef CONFIG_PRINTK
28/*
29 * ratelimit state to be used in DMXXX_LIMIT().
30 */
31DEFINE_RATELIMIT_STATE(dm_ratelimit_state,
32               DEFAULT_RATELIMIT_INTERVAL,
33               DEFAULT_RATELIMIT_BURST);
34EXPORT_SYMBOL(dm_ratelimit_state);
35#endif
36
37/*
38 * Cookies are numeric values sent with CHANGE and REMOVE
39 * uevents while resuming, removing or renaming the device.
40 */
41#define DM_COOKIE_ENV_VAR_NAME "DM_COOKIE"
42#define DM_COOKIE_LENGTH 24
43
44static const char *_name = DM_NAME;
45
46static unsigned int major = 0;
47static unsigned int _major = 0;
48
49static DEFINE_IDR(_minor_idr);
50
51static DEFINE_SPINLOCK(_minor_lock);
52/*
53 * For bio-based dm.
54 * One of these is allocated per bio.
55 */
56struct dm_io {
57    struct mapped_device *md;
58    int error;
59    atomic_t io_count;
60    struct bio *bio;
61    unsigned long start_time;
62    spinlock_t endio_lock;
63};
64
65/*
66 * For request-based dm.
67 * One of these is allocated per request.
68 */
69struct dm_rq_target_io {
70    struct mapped_device *md;
71    struct dm_target *ti;
72    struct request *orig, clone;
73    int error;
74    union map_info info;
75};
76
77/*
78 * For request-based dm - the bio clones we allocate are embedded in these
79 * structs.
80 *
81 * We allocate these with bio_alloc_bioset, using the front_pad parameter when
82 * the bioset is created - this means the bio has to come at the end of the
83 * struct.
84 */
85struct dm_rq_clone_bio_info {
86    struct bio *orig;
87    struct dm_rq_target_io *tio;
88    struct bio clone;
89};
90
91union map_info *dm_get_mapinfo(struct bio *bio)
92{
93    if (bio && bio->bi_private)
94        return &((struct dm_target_io *)bio->bi_private)->info;
95    return NULL;
96}
97
98union map_info *dm_get_rq_mapinfo(struct request *rq)
99{
100    if (rq && rq->end_io_data)
101        return &((struct dm_rq_target_io *)rq->end_io_data)->info;
102    return NULL;
103}
104EXPORT_SYMBOL_GPL(dm_get_rq_mapinfo);
105
106#define MINOR_ALLOCED ((void *)-1)
107
108/*
109 * Bits for the md->flags field.
110 */
111#define DMF_BLOCK_IO_FOR_SUSPEND 0
112#define DMF_SUSPENDED 1
113#define DMF_FROZEN 2
114#define DMF_FREEING 3
115#define DMF_DELETING 4
116#define DMF_NOFLUSH_SUSPENDING 5
117#define DMF_MERGE_IS_OPTIONAL 6
118
119/*
120 * Work processed by per-device workqueue.
121 */
122struct mapped_device {
123    struct rw_semaphore io_lock;
124    struct mutex suspend_lock;
125    rwlock_t map_lock;
126    atomic_t holders;
127    atomic_t open_count;
128
129    unsigned long flags;
130
131    struct request_queue *queue;
132    unsigned type;
133    /* Protect queue and type against concurrent access. */
134    struct mutex type_lock;
135
136    struct target_type *immutable_target_type;
137
138    struct gendisk *disk;
139    char name[16];
140
141    void *interface_ptr;
142
143    /*
144     * A list of ios that arrived while we were suspended.
145     */
146    atomic_t pending[2];
147    wait_queue_head_t wait;
148    struct work_struct work;
149    struct bio_list deferred;
150    spinlock_t deferred_lock;
151
152    /*
153     * Processing queue (flush)
154     */
155    struct workqueue_struct *wq;
156
157    /*
158     * The current mapping.
159     */
160    struct dm_table *map;
161
162    /*
163     * io objects are allocated from here.
164     */
165    mempool_t *io_pool;
166
167    struct bio_set *bs;
168
169    /*
170     * Event handling.
171     */
172    atomic_t event_nr;
173    wait_queue_head_t eventq;
174    atomic_t uevent_seq;
175    struct list_head uevent_list;
176    spinlock_t uevent_lock; /* Protect access to uevent_list */
177
178    /*
179     * freeze/thaw support require holding onto a super block
180     */
181    struct super_block *frozen_sb;
182    struct block_device *bdev;
183
184    /* forced geometry settings */
185    struct hd_geometry geometry;
186
187    /* sysfs handle */
188    struct kobject kobj;
189
190    /* zero-length flush that will be cloned and submitted to targets */
191    struct bio flush_bio;
192};
193
194/*
195 * For mempools pre-allocation at the table loading time.
196 */
197struct dm_md_mempools {
198    mempool_t *io_pool;
199    struct bio_set *bs;
200};
201
202#define MIN_IOS 256
203static struct kmem_cache *_io_cache;
204static struct kmem_cache *_rq_tio_cache;
205
206static int __init local_init(void)
207{
208    int r = -ENOMEM;
209
210    /* allocate a slab for the dm_ios */
211    _io_cache = KMEM_CACHE(dm_io, 0);
212    if (!_io_cache)
213        return r;
214
215    _rq_tio_cache = KMEM_CACHE(dm_rq_target_io, 0);
216    if (!_rq_tio_cache)
217        goto out_free_io_cache;
218
219    r = dm_uevent_init();
220    if (r)
221        goto out_free_rq_tio_cache;
222
223    _major = major;
224    r = register_blkdev(_major, _name);
225    if (r < 0)
226        goto out_uevent_exit;
227
228    if (!_major)
229        _major = r;
230
231    return 0;
232
233out_uevent_exit:
234    dm_uevent_exit();
235out_free_rq_tio_cache:
236    kmem_cache_destroy(_rq_tio_cache);
237out_free_io_cache:
238    kmem_cache_destroy(_io_cache);
239
240    return r;
241}
242
243static void local_exit(void)
244{
245    kmem_cache_destroy(_rq_tio_cache);
246    kmem_cache_destroy(_io_cache);
247    unregister_blkdev(_major, _name);
248    dm_uevent_exit();
249
250    _major = 0;
251
252    DMINFO("cleaned up");
253}
254
255static int (*_inits[])(void) __initdata = {
256    local_init,
257    dm_target_init,
258    dm_linear_init,
259    dm_stripe_init,
260    dm_io_init,
261    dm_kcopyd_init,
262    dm_interface_init,
263};
264
265static void (*_exits[])(void) = {
266    local_exit,
267    dm_target_exit,
268    dm_linear_exit,
269    dm_stripe_exit,
270    dm_io_exit,
271    dm_kcopyd_exit,
272    dm_interface_exit,
273};
274
275static int __init dm_init(void)
276{
277    const int count = ARRAY_SIZE(_inits);
278
279    int r, i;
280
281    for (i = 0; i < count; i++) {
282        r = _inits[i]();
283        if (r)
284            goto bad;
285    }
286
287    return 0;
288
289      bad:
290    while (i--)
291        _exits[i]();
292
293    return r;
294}
295
296static void __exit dm_exit(void)
297{
298    int i = ARRAY_SIZE(_exits);
299
300    while (i--)
301        _exits[i]();
302
303    /*
304     * Should be empty by this point.
305     */
306    idr_destroy(&_minor_idr);
307}
308
309/*
310 * Block device functions
311 */
312int dm_deleting_md(struct mapped_device *md)
313{
314    return test_bit(DMF_DELETING, &md->flags);
315}
316
317static int dm_blk_open(struct block_device *bdev, fmode_t mode)
318{
319    struct mapped_device *md;
320
321    spin_lock(&_minor_lock);
322
323    md = bdev->bd_disk->private_data;
324    if (!md)
325        goto out;
326
327    if (test_bit(DMF_FREEING, &md->flags) ||
328        dm_deleting_md(md)) {
329        md = NULL;
330        goto out;
331    }
332
333    dm_get(md);
334    atomic_inc(&md->open_count);
335
336out:
337    spin_unlock(&_minor_lock);
338
339    return md ? 0 : -ENXIO;
340}
341
342static int dm_blk_close(struct gendisk *disk, fmode_t mode)
343{
344    struct mapped_device *md = disk->private_data;
345
346    spin_lock(&_minor_lock);
347
348    atomic_dec(&md->open_count);
349    dm_put(md);
350
351    spin_unlock(&_minor_lock);
352
353    return 0;
354}
355
356int dm_open_count(struct mapped_device *md)
357{
358    return atomic_read(&md->open_count);
359}
360
361/*
362 * Guarantees nothing is using the device before it's deleted.
363 */
364int dm_lock_for_deletion(struct mapped_device *md)
365{
366    int r = 0;
367
368    spin_lock(&_minor_lock);
369
370    if (dm_open_count(md))
371        r = -EBUSY;
372    else
373        set_bit(DMF_DELETING, &md->flags);
374
375    spin_unlock(&_minor_lock);
376
377    return r;
378}
379
380static int dm_blk_getgeo(struct block_device *bdev, struct hd_geometry *geo)
381{
382    struct mapped_device *md = bdev->bd_disk->private_data;
383
384    return dm_get_geometry(md, geo);
385}
386
387static int dm_blk_ioctl(struct block_device *bdev, fmode_t mode,
388            unsigned int cmd, unsigned long arg)
389{
390    struct mapped_device *md = bdev->bd_disk->private_data;
391    struct dm_table *map = dm_get_live_table(md);
392    struct dm_target *tgt;
393    int r = -ENOTTY;
394
395    if (!map || !dm_table_get_size(map))
396        goto out;
397
398    /* We only support devices that have a single target */
399    if (dm_table_get_num_targets(map) != 1)
400        goto out;
401
402    tgt = dm_table_get_target(map, 0);
403
404    if (dm_suspended_md(md)) {
405        r = -EAGAIN;
406        goto out;
407    }
408
409    if (tgt->type->ioctl)
410        r = tgt->type->ioctl(tgt, cmd, arg);
411
412out:
413    dm_table_put(map);
414
415    return r;
416}
417
418static struct dm_io *alloc_io(struct mapped_device *md)
419{
420    return mempool_alloc(md->io_pool, GFP_NOIO);
421}
422
423static void free_io(struct mapped_device *md, struct dm_io *io)
424{
425    mempool_free(io, md->io_pool);
426}
427
428static void free_tio(struct mapped_device *md, struct dm_target_io *tio)
429{
430    bio_put(&tio->clone);
431}
432
433static struct dm_rq_target_io *alloc_rq_tio(struct mapped_device *md,
434                        gfp_t gfp_mask)
435{
436    return mempool_alloc(md->io_pool, gfp_mask);
437}
438
439static void free_rq_tio(struct dm_rq_target_io *tio)
440{
441    mempool_free(tio, tio->md->io_pool);
442}
443
444static int md_in_flight(struct mapped_device *md)
445{
446    return atomic_read(&md->pending[READ]) +
447           atomic_read(&md->pending[WRITE]);
448}
449
450static void start_io_acct(struct dm_io *io)
451{
452    struct mapped_device *md = io->md;
453    int cpu;
454    int rw = bio_data_dir(io->bio);
455
456    io->start_time = jiffies;
457
458    cpu = part_stat_lock();
459    part_round_stats(cpu, &dm_disk(md)->part0);
460    part_stat_unlock();
461    atomic_set(&dm_disk(md)->part0.in_flight[rw],
462        atomic_inc_return(&md->pending[rw]));
463}
464
465static void end_io_acct(struct dm_io *io)
466{
467    struct mapped_device *md = io->md;
468    struct bio *bio = io->bio;
469    unsigned long duration = jiffies - io->start_time;
470    int pending, cpu;
471    int rw = bio_data_dir(bio);
472
473    cpu = part_stat_lock();
474    part_round_stats(cpu, &dm_disk(md)->part0);
475    part_stat_add(cpu, &dm_disk(md)->part0, ticks[rw], duration);
476    part_stat_unlock();
477
478    /*
479     * After this is decremented the bio must not be touched if it is
480     * a flush.
481     */
482    pending = atomic_dec_return(&md->pending[rw]);
483    atomic_set(&dm_disk(md)->part0.in_flight[rw], pending);
484    pending += atomic_read(&md->pending[rw^0x1]);
485
486    /* nudge anyone waiting on suspend queue */
487    if (!pending)
488        wake_up(&md->wait);
489}
490
491/*
492 * Add the bio to the list of deferred io.
493 */
494static void queue_io(struct mapped_device *md, struct bio *bio)
495{
496    unsigned long flags;
497
498    spin_lock_irqsave(&md->deferred_lock, flags);
499    bio_list_add(&md->deferred, bio);
500    spin_unlock_irqrestore(&md->deferred_lock, flags);
501    queue_work(md->wq, &md->work);
502}
503
504/*
505 * Everyone (including functions in this file), should use this
506 * function to access the md->map field, and make sure they call
507 * dm_table_put() when finished.
508 */
509struct dm_table *dm_get_live_table(struct mapped_device *md)
510{
511    struct dm_table *t;
512    unsigned long flags;
513
514    read_lock_irqsave(&md->map_lock, flags);
515    t = md->map;
516    if (t)
517        dm_table_get(t);
518    read_unlock_irqrestore(&md->map_lock, flags);
519
520    return t;
521}
522
523/*
524 * Get the geometry associated with a dm device
525 */
526int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo)
527{
528    *geo = md->geometry;
529
530    return 0;
531}
532
533/*
534 * Set the geometry of a device.
535 */
536int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo)
537{
538    sector_t sz = (sector_t)geo->cylinders * geo->heads * geo->sectors;
539
540    if (geo->start > sz) {
541        DMWARN("Start sector is beyond the geometry limits.");
542        return -EINVAL;
543    }
544
545    md->geometry = *geo;
546
547    return 0;
548}
549
550/*-----------------------------------------------------------------
551 * CRUD START:
552 * A more elegant soln is in the works that uses the queue
553 * merge fn, unfortunately there are a couple of changes to
554 * the block layer that I want to make for this. So in the
555 * interests of getting something for people to use I give
556 * you this clearly demarcated crap.
557 *---------------------------------------------------------------*/
558
559static int __noflush_suspending(struct mapped_device *md)
560{
561    return test_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
562}
563
564/*
565 * Decrements the number of outstanding ios that a bio has been
566 * cloned into, completing the original io if necc.
567 */
568static void dec_pending(struct dm_io *io, int error)
569{
570    unsigned long flags;
571    int io_error;
572    struct bio *bio;
573    struct mapped_device *md = io->md;
574
575    /* Push-back supersedes any I/O errors */
576    if (unlikely(error)) {
577        spin_lock_irqsave(&io->endio_lock, flags);
578        if (!(io->error > 0 && __noflush_suspending(md)))
579            io->error = error;
580        spin_unlock_irqrestore(&io->endio_lock, flags);
581    }
582
583    if (atomic_dec_and_test(&io->io_count)) {
584        if (io->error == DM_ENDIO_REQUEUE) {
585            /*
586             * Target requested pushing back the I/O.
587             */
588            spin_lock_irqsave(&md->deferred_lock, flags);
589            if (__noflush_suspending(md))
590                bio_list_add_head(&md->deferred, io->bio);
591            else
592                /* noflush suspend was interrupted. */
593                io->error = -EIO;
594            spin_unlock_irqrestore(&md->deferred_lock, flags);
595        }
596
597        io_error = io->error;
598        bio = io->bio;
599        end_io_acct(io);
600        free_io(md, io);
601
602        if (io_error == DM_ENDIO_REQUEUE)
603            return;
604
605        if ((bio->bi_rw & REQ_FLUSH) && bio->bi_size) {
606            /*
607             * Preflush done for flush with data, reissue
608             * without REQ_FLUSH.
609             */
610            bio->bi_rw &= ~REQ_FLUSH;
611            queue_io(md, bio);
612        } else {
613            /* done with normal IO or empty flush */
614            trace_block_bio_complete(md->queue, bio, io_error);
615            bio_endio(bio, io_error);
616        }
617    }
618}
619
620static void clone_endio(struct bio *bio, int error)
621{
622    int r = 0;
623    struct dm_target_io *tio = bio->bi_private;
624    struct dm_io *io = tio->io;
625    struct mapped_device *md = tio->io->md;
626    dm_endio_fn endio = tio->ti->type->end_io;
627
628    if (!bio_flagged(bio, BIO_UPTODATE) && !error)
629        error = -EIO;
630
631    if (endio) {
632        r = endio(tio->ti, bio, error);
633        if (r < 0 || r == DM_ENDIO_REQUEUE)
634            /*
635             * error and requeue request are handled
636             * in dec_pending().
637             */
638            error = r;
639        else if (r == DM_ENDIO_INCOMPLETE)
640            /* The target will handle the io */
641            return;
642        else if (r) {
643            DMWARN("unimplemented target endio return value: %d", r);
644            BUG();
645        }
646    }
647
648    free_tio(md, tio);
649    dec_pending(io, error);
650}
651
652/*
653 * Partial completion handling for request-based dm
654 */
655static void end_clone_bio(struct bio *clone, int error)
656{
657    struct dm_rq_clone_bio_info *info = clone->bi_private;
658    struct dm_rq_target_io *tio = info->tio;
659    struct bio *bio = info->orig;
660    unsigned int nr_bytes = info->orig->bi_size;
661
662    bio_put(clone);
663
664    if (tio->error)
665        /*
666         * An error has already been detected on the request.
667         * Once error occurred, just let clone->end_io() handle
668         * the remainder.
669         */
670        return;
671    else if (error) {
672        /*
673         * Don't notice the error to the upper layer yet.
674         * The error handling decision is made by the target driver,
675         * when the request is completed.
676         */
677        tio->error = error;
678        return;
679    }
680
681    /*
682     * I/O for the bio successfully completed.
683     * Notice the data completion to the upper layer.
684     */
685
686    /*
687     * bios are processed from the head of the list.
688     * So the completing bio should always be rq->bio.
689     * If it's not, something wrong is happening.
690     */
691    if (tio->orig->bio != bio)
692        DMERR("bio completion is going in the middle of the request");
693
694    /*
695     * Update the original request.
696     * Do not use blk_end_request() here, because it may complete
697     * the original request before the clone, and break the ordering.
698     */
699    blk_update_request(tio->orig, 0, nr_bytes);
700}
701
702/*
703 * Don't touch any member of the md after calling this function because
704 * the md may be freed in dm_put() at the end of this function.
705 * Or do dm_get() before calling this function and dm_put() later.
706 */
707static void rq_completed(struct mapped_device *md, int rw, int run_queue)
708{
709    atomic_dec(&md->pending[rw]);
710
711    /* nudge anyone waiting on suspend queue */
712    if (!md_in_flight(md))
713        wake_up(&md->wait);
714
715    /*
716     * Run this off this callpath, as drivers could invoke end_io while
717     * inside their request_fn (and holding the queue lock). Calling
718     * back into ->request_fn() could deadlock attempting to grab the
719     * queue lock again.
720     */
721    if (run_queue)
722        blk_run_queue_async(md->queue);
723
724    /*
725     * dm_put() must be at the end of this function. See the comment above
726     */
727    dm_put(md);
728}
729
730static void free_rq_clone(struct request *clone)
731{
732    struct dm_rq_target_io *tio = clone->end_io_data;
733
734    blk_rq_unprep_clone(clone);
735    free_rq_tio(tio);
736}
737
738/*
739 * Complete the clone and the original request.
740 * Must be called without queue lock.
741 */
742static void dm_end_request(struct request *clone, int error)
743{
744    int rw = rq_data_dir(clone);
745    struct dm_rq_target_io *tio = clone->end_io_data;
746    struct mapped_device *md = tio->md;
747    struct request *rq = tio->orig;
748
749    if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
750        rq->errors = clone->errors;
751        rq->resid_len = clone->resid_len;
752
753        if (rq->sense)
754            /*
755             * We are using the sense buffer of the original
756             * request.
757             * So setting the length of the sense data is enough.
758             */
759            rq->sense_len = clone->sense_len;
760    }
761
762    free_rq_clone(clone);
763    blk_end_request_all(rq, error);
764    rq_completed(md, rw, true);
765}
766
767static void dm_unprep_request(struct request *rq)
768{
769    struct request *clone = rq->special;
770
771    rq->special = NULL;
772    rq->cmd_flags &= ~REQ_DONTPREP;
773
774    free_rq_clone(clone);
775}
776
777/*
778 * Requeue the original request of a clone.
779 */
780void dm_requeue_unmapped_request(struct request *clone)
781{
782    int rw = rq_data_dir(clone);
783    struct dm_rq_target_io *tio = clone->end_io_data;
784    struct mapped_device *md = tio->md;
785    struct request *rq = tio->orig;
786    struct request_queue *q = rq->q;
787    unsigned long flags;
788
789    dm_unprep_request(rq);
790
791    spin_lock_irqsave(q->queue_lock, flags);
792    blk_requeue_request(q, rq);
793    spin_unlock_irqrestore(q->queue_lock, flags);
794
795    rq_completed(md, rw, 0);
796}
797EXPORT_SYMBOL_GPL(dm_requeue_unmapped_request);
798
799static void __stop_queue(struct request_queue *q)
800{
801    blk_stop_queue(q);
802}
803
804static void stop_queue(struct request_queue *q)
805{
806    unsigned long flags;
807
808    spin_lock_irqsave(q->queue_lock, flags);
809    __stop_queue(q);
810    spin_unlock_irqrestore(q->queue_lock, flags);
811}
812
813static void __start_queue(struct request_queue *q)
814{
815    if (blk_queue_stopped(q))
816        blk_start_queue(q);
817}
818
819static void start_queue(struct request_queue *q)
820{
821    unsigned long flags;
822
823    spin_lock_irqsave(q->queue_lock, flags);
824    __start_queue(q);
825    spin_unlock_irqrestore(q->queue_lock, flags);
826}
827
828static void dm_done(struct request *clone, int error, bool mapped)
829{
830    int r = error;
831    struct dm_rq_target_io *tio = clone->end_io_data;
832    dm_request_endio_fn rq_end_io = NULL;
833
834    if (tio->ti) {
835        rq_end_io = tio->ti->type->rq_end_io;
836
837        if (mapped && rq_end_io)
838            r = rq_end_io(tio->ti, clone, error, &tio->info);
839    }
840
841    if (r <= 0)
842        /* The target wants to complete the I/O */
843        dm_end_request(clone, r);
844    else if (r == DM_ENDIO_INCOMPLETE)
845        /* The target will handle the I/O */
846        return;
847    else if (r == DM_ENDIO_REQUEUE)
848        /* The target wants to requeue the I/O */
849        dm_requeue_unmapped_request(clone);
850    else {
851        DMWARN("unimplemented target endio return value: %d", r);
852        BUG();
853    }
854}
855
856/*
857 * Request completion handler for request-based dm
858 */
859static void dm_softirq_done(struct request *rq)
860{
861    bool mapped = true;
862    struct request *clone = rq->completion_data;
863    struct dm_rq_target_io *tio = clone->end_io_data;
864
865    if (rq->cmd_flags & REQ_FAILED)
866        mapped = false;
867
868    dm_done(clone, tio->error, mapped);
869}
870
871/*
872 * Complete the clone and the original request with the error status
873 * through softirq context.
874 */
875static void dm_complete_request(struct request *clone, int error)
876{
877    struct dm_rq_target_io *tio = clone->end_io_data;
878    struct request *rq = tio->orig;
879
880    tio->error = error;
881    rq->completion_data = clone;
882    blk_complete_request(rq);
883}
884
885/*
886 * Complete the not-mapped clone and the original request with the error status
887 * through softirq context.
888 * Target's rq_end_io() function isn't called.
889 * This may be used when the target's map_rq() function fails.
890 */
891void dm_kill_unmapped_request(struct request *clone, int error)
892{
893    struct dm_rq_target_io *tio = clone->end_io_data;
894    struct request *rq = tio->orig;
895
896    rq->cmd_flags |= REQ_FAILED;
897    dm_complete_request(clone, error);
898}
899EXPORT_SYMBOL_GPL(dm_kill_unmapped_request);
900
901/*
902 * Called with the queue lock held
903 */
904static void end_clone_request(struct request *clone, int error)
905{
906    /*
907     * For just cleaning up the information of the queue in which
908     * the clone was dispatched.
909     * The clone is *NOT* freed actually here because it is alloced from
910     * dm own mempool and REQ_ALLOCED isn't set in clone->cmd_flags.
911     */
912    __blk_put_request(clone->q, clone);
913
914    /*
915     * Actual request completion is done in a softirq context which doesn't
916     * hold the queue lock. Otherwise, deadlock could occur because:
917     * - another request may be submitted by the upper level driver
918     * of the stacking during the completion
919     * - the submission which requires queue lock may be done
920     * against this queue
921     */
922    dm_complete_request(clone, error);
923}
924
925/*
926 * Return maximum size of I/O possible at the supplied sector up to the current
927 * target boundary.
928 */
929static sector_t max_io_len_target_boundary(sector_t sector, struct dm_target *ti)
930{
931    sector_t target_offset = dm_target_offset(ti, sector);
932
933    return ti->len - target_offset;
934}
935
936static sector_t max_io_len(sector_t sector, struct dm_target *ti)
937{
938    sector_t len = max_io_len_target_boundary(sector, ti);
939    sector_t offset, max_len;
940
941    /*
942     * Does the target need to split even further?
943     */
944    if (ti->max_io_len) {
945        offset = dm_target_offset(ti, sector);
946        if (unlikely(ti->max_io_len & (ti->max_io_len - 1)))
947            max_len = sector_div(offset, ti->max_io_len);
948        else
949            max_len = offset & (ti->max_io_len - 1);
950        max_len = ti->max_io_len - max_len;
951
952        if (len > max_len)
953            len = max_len;
954    }
955
956    return len;
957}
958
959int dm_set_target_max_io_len(struct dm_target *ti, sector_t len)
960{
961    if (len > UINT_MAX) {
962        DMERR("Specified maximum size of target IO (%llu) exceeds limit (%u)",
963              (unsigned long long)len, UINT_MAX);
964        ti->error = "Maximum size of target IO is too large";
965        return -EINVAL;
966    }
967
968    ti->max_io_len = (uint32_t) len;
969
970    return 0;
971}
972EXPORT_SYMBOL_GPL(dm_set_target_max_io_len);
973
974static void __map_bio(struct dm_target_io *tio)
975{
976    int r;
977    sector_t sector;
978    struct mapped_device *md;
979    struct bio *clone = &tio->clone;
980    struct dm_target *ti = tio->ti;
981
982    clone->bi_end_io = clone_endio;
983    clone->bi_private = tio;
984
985    /*
986     * Map the clone. If r == 0 we don't need to do
987     * anything, the target has assumed ownership of
988     * this io.
989     */
990    atomic_inc(&tio->io->io_count);
991    sector = clone->bi_sector;
992    r = ti->type->map(ti, clone);
993    if (r == DM_MAPIO_REMAPPED) {
994        /* the bio has been remapped so dispatch it */
995
996        trace_block_bio_remap(bdev_get_queue(clone->bi_bdev), clone,
997                      tio->io->bio->bi_bdev->bd_dev, sector);
998
999        generic_make_request(clone);
1000    } else if (r < 0 || r == DM_MAPIO_REQUEUE) {
1001        /* error the io and bail out, or requeue it if needed */
1002        md = tio->io->md;
1003        dec_pending(tio->io, r);
1004        free_tio(md, tio);
1005    } else if (r) {
1006        DMWARN("unimplemented target map return value: %d", r);
1007        BUG();
1008    }
1009}
1010
1011struct clone_info {
1012    struct mapped_device *md;
1013    struct dm_table *map;
1014    struct bio *bio;
1015    struct dm_io *io;
1016    sector_t sector;
1017    sector_t sector_count;
1018    unsigned short idx;
1019};
1020
1021static void bio_setup_sector(struct bio *bio, sector_t sector, sector_t len)
1022{
1023    bio->bi_sector = sector;
1024    bio->bi_size = to_bytes(len);
1025}
1026
1027static void bio_setup_bv(struct bio *bio, unsigned short idx, unsigned short bv_count)
1028{
1029    bio->bi_idx = idx;
1030    bio->bi_vcnt = idx + bv_count;
1031    bio->bi_flags &= ~(1 << BIO_SEG_VALID);
1032}
1033
1034static void clone_bio_integrity(struct bio *bio, struct bio *clone,
1035                unsigned short idx, unsigned len, unsigned offset,
1036                unsigned trim)
1037{
1038    if (!bio_integrity(bio))
1039        return;
1040
1041    bio_integrity_clone(clone, bio, GFP_NOIO);
1042
1043    if (trim)
1044        bio_integrity_trim(clone, bio_sector_offset(bio, idx, offset), len);
1045}
1046
1047/*
1048 * Creates a little bio that just does part of a bvec.
1049 */
1050static void clone_split_bio(struct dm_target_io *tio, struct bio *bio,
1051                sector_t sector, unsigned short idx,
1052                unsigned offset, unsigned len)
1053{
1054    struct bio *clone = &tio->clone;
1055    struct bio_vec *bv = bio->bi_io_vec + idx;
1056
1057    *clone->bi_io_vec = *bv;
1058
1059    bio_setup_sector(clone, sector, len);
1060
1061    clone->bi_bdev = bio->bi_bdev;
1062    clone->bi_rw = bio->bi_rw;
1063    clone->bi_vcnt = 1;
1064    clone->bi_io_vec->bv_offset = offset;
1065    clone->bi_io_vec->bv_len = clone->bi_size;
1066    clone->bi_flags |= 1 << BIO_CLONED;
1067
1068    clone_bio_integrity(bio, clone, idx, len, offset, 1);
1069}
1070
1071/*
1072 * Creates a bio that consists of range of complete bvecs.
1073 */
1074static void clone_bio(struct dm_target_io *tio, struct bio *bio,
1075              sector_t sector, unsigned short idx,
1076              unsigned short bv_count, unsigned len)
1077{
1078    struct bio *clone = &tio->clone;
1079    unsigned trim = 0;
1080
1081    __bio_clone(clone, bio);
1082    bio_setup_sector(clone, sector, len);
1083    bio_setup_bv(clone, idx, bv_count);
1084
1085    if (idx != bio->bi_idx || clone->bi_size < bio->bi_size)
1086        trim = 1;
1087    clone_bio_integrity(bio, clone, idx, len, 0, trim);
1088}
1089
1090static struct dm_target_io *alloc_tio(struct clone_info *ci,
1091                      struct dm_target *ti, int nr_iovecs,
1092                      unsigned target_bio_nr)
1093{
1094    struct dm_target_io *tio;
1095    struct bio *clone;
1096
1097    clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, ci->md->bs);
1098    tio = container_of(clone, struct dm_target_io, clone);
1099
1100    tio->io = ci->io;
1101    tio->ti = ti;
1102    memset(&tio->info, 0, sizeof(tio->info));
1103    tio->target_bio_nr = target_bio_nr;
1104
1105    return tio;
1106}
1107
1108static void __clone_and_map_simple_bio(struct clone_info *ci,
1109                       struct dm_target *ti,
1110                       unsigned target_bio_nr, sector_t len)
1111{
1112    struct dm_target_io *tio = alloc_tio(ci, ti, ci->bio->bi_max_vecs, target_bio_nr);
1113    struct bio *clone = &tio->clone;
1114
1115    /*
1116     * Discard requests require the bio's inline iovecs be initialized.
1117     * ci->bio->bi_max_vecs is BIO_INLINE_VECS anyway, for both flush
1118     * and discard, so no need for concern about wasted bvec allocations.
1119     */
1120     __bio_clone(clone, ci->bio);
1121    if (len)
1122        bio_setup_sector(clone, ci->sector, len);
1123
1124    __map_bio(tio);
1125}
1126
1127static void __send_duplicate_bios(struct clone_info *ci, struct dm_target *ti,
1128                  unsigned num_bios, sector_t len)
1129{
1130    unsigned target_bio_nr;
1131
1132    for (target_bio_nr = 0; target_bio_nr < num_bios; target_bio_nr++)
1133        __clone_and_map_simple_bio(ci, ti, target_bio_nr, len);
1134}
1135
1136static int __send_empty_flush(struct clone_info *ci)
1137{
1138    unsigned target_nr = 0;
1139    struct dm_target *ti;
1140
1141    BUG_ON(bio_has_data(ci->bio));
1142    while ((ti = dm_table_get_target(ci->map, target_nr++)))
1143        __send_duplicate_bios(ci, ti, ti->num_flush_bios, 0);
1144
1145    return 0;
1146}
1147
1148static void __clone_and_map_data_bio(struct clone_info *ci, struct dm_target *ti,
1149                     sector_t sector, int nr_iovecs,
1150                     unsigned short idx, unsigned short bv_count,
1151                     unsigned offset, unsigned len,
1152                     unsigned split_bvec)
1153{
1154    struct bio *bio = ci->bio;
1155    struct dm_target_io *tio;
1156    unsigned target_bio_nr;
1157    unsigned num_target_bios = 1;
1158
1159    /*
1160     * Does the target want to receive duplicate copies of the bio?
1161     */
1162    if (bio_data_dir(bio) == WRITE && ti->num_write_bios)
1163        num_target_bios = ti->num_write_bios(ti, bio);
1164
1165    for (target_bio_nr = 0; target_bio_nr < num_target_bios; target_bio_nr++) {
1166        tio = alloc_tio(ci, ti, nr_iovecs, target_bio_nr);
1167        if (split_bvec)
1168            clone_split_bio(tio, bio, sector, idx, offset, len);
1169        else
1170            clone_bio(tio, bio, sector, idx, bv_count, len);
1171        __map_bio(tio);
1172    }
1173}
1174
1175typedef unsigned (*get_num_bios_fn)(struct dm_target *ti);
1176
1177static unsigned get_num_discard_bios(struct dm_target *ti)
1178{
1179    return ti->num_discard_bios;
1180}
1181
1182static unsigned get_num_write_same_bios(struct dm_target *ti)
1183{
1184    return ti->num_write_same_bios;
1185}
1186
1187typedef bool (*is_split_required_fn)(struct dm_target *ti);
1188
1189static bool is_split_required_for_discard(struct dm_target *ti)
1190{
1191    return ti->split_discard_bios;
1192}
1193
1194static int __send_changing_extent_only(struct clone_info *ci,
1195                       get_num_bios_fn get_num_bios,
1196                       is_split_required_fn is_split_required)
1197{
1198    struct dm_target *ti;
1199    sector_t len;
1200    unsigned num_bios;
1201
1202    do {
1203        ti = dm_table_find_target(ci->map, ci->sector);
1204        if (!dm_target_is_valid(ti))
1205            return -EIO;
1206
1207        /*
1208         * Even though the device advertised support for this type of
1209         * request, that does not mean every target supports it, and
1210         * reconfiguration might also have changed that since the
1211         * check was performed.
1212         */
1213        num_bios = get_num_bios ? get_num_bios(ti) : 0;
1214        if (!num_bios)
1215            return -EOPNOTSUPP;
1216
1217        if (is_split_required && !is_split_required(ti))
1218            len = min(ci->sector_count, max_io_len_target_boundary(ci->sector, ti));
1219        else
1220            len = min(ci->sector_count, max_io_len(ci->sector, ti));
1221
1222        __send_duplicate_bios(ci, ti, num_bios, len);
1223
1224        ci->sector += len;
1225    } while (ci->sector_count -= len);
1226
1227    return 0;
1228}
1229
1230static int __send_discard(struct clone_info *ci)
1231{
1232    return __send_changing_extent_only(ci, get_num_discard_bios,
1233                       is_split_required_for_discard);
1234}
1235
1236static int __send_write_same(struct clone_info *ci)
1237{
1238    return __send_changing_extent_only(ci, get_num_write_same_bios, NULL);
1239}
1240
1241/*
1242 * Find maximum number of sectors / bvecs we can process with a single bio.
1243 */
1244static sector_t __len_within_target(struct clone_info *ci, sector_t max, int *idx)
1245{
1246    struct bio *bio = ci->bio;
1247    sector_t bv_len, total_len = 0;
1248
1249    for (*idx = ci->idx; max && (*idx < bio->bi_vcnt); (*idx)++) {
1250        bv_len = to_sector(bio->bi_io_vec[*idx].bv_len);
1251
1252        if (bv_len > max)
1253            break;
1254
1255        max -= bv_len;
1256        total_len += bv_len;
1257    }
1258
1259    return total_len;
1260}
1261
1262static int __split_bvec_across_targets(struct clone_info *ci,
1263                       struct dm_target *ti, sector_t max)
1264{
1265    struct bio *bio = ci->bio;
1266    struct bio_vec *bv = bio->bi_io_vec + ci->idx;
1267    sector_t remaining = to_sector(bv->bv_len);
1268    unsigned offset = 0;
1269    sector_t len;
1270
1271    do {
1272        if (offset) {
1273            ti = dm_table_find_target(ci->map, ci->sector);
1274            if (!dm_target_is_valid(ti))
1275                return -EIO;
1276
1277            max = max_io_len(ci->sector, ti);
1278        }
1279
1280        len = min(remaining, max);
1281
1282        __clone_and_map_data_bio(ci, ti, ci->sector, 1, ci->idx, 0,
1283                     bv->bv_offset + offset, len, 1);
1284
1285        ci->sector += len;
1286        ci->sector_count -= len;
1287        offset += to_bytes(len);
1288    } while (remaining -= len);
1289
1290    ci->idx++;
1291
1292    return 0;
1293}
1294
1295/*
1296 * Select the correct strategy for processing a non-flush bio.
1297 */
1298static int __split_and_process_non_flush(struct clone_info *ci)
1299{
1300    struct bio *bio = ci->bio;
1301    struct dm_target *ti;
1302    sector_t len, max;
1303    int idx;
1304
1305    if (unlikely(bio->bi_rw & REQ_DISCARD))
1306        return __send_discard(ci);
1307    else if (unlikely(bio->bi_rw & REQ_WRITE_SAME))
1308        return __send_write_same(ci);
1309
1310    ti = dm_table_find_target(ci->map, ci->sector);
1311    if (!dm_target_is_valid(ti))
1312        return -EIO;
1313
1314    max = max_io_len(ci->sector, ti);
1315
1316    /*
1317     * Optimise for the simple case where we can do all of
1318     * the remaining io with a single clone.
1319     */
1320    if (ci->sector_count <= max) {
1321        __clone_and_map_data_bio(ci, ti, ci->sector, bio->bi_max_vecs,
1322                     ci->idx, bio->bi_vcnt - ci->idx, 0,
1323                     ci->sector_count, 0);
1324        ci->sector_count = 0;
1325        return 0;
1326    }
1327
1328    /*
1329     * There are some bvecs that don't span targets.
1330     * Do as many of these as possible.
1331     */
1332    if (to_sector(bio->bi_io_vec[ci->idx].bv_len) <= max) {
1333        len = __len_within_target(ci, max, &idx);
1334
1335        __clone_and_map_data_bio(ci, ti, ci->sector, bio->bi_max_vecs,
1336                     ci->idx, idx - ci->idx, 0, len, 0);
1337
1338        ci->sector += len;
1339        ci->sector_count -= len;
1340        ci->idx = idx;
1341
1342        return 0;
1343    }
1344
1345    /*
1346     * Handle a bvec that must be split between two or more targets.
1347     */
1348    return __split_bvec_across_targets(ci, ti, max);
1349}
1350
1351/*
1352 * Entry point to split a bio into clones and submit them to the targets.
1353 */
1354static void __split_and_process_bio(struct mapped_device *md, struct bio *bio)
1355{
1356    struct clone_info ci;
1357    int error = 0;
1358
1359    ci.map = dm_get_live_table(md);
1360    if (unlikely(!ci.map)) {
1361        bio_io_error(bio);
1362        return;
1363    }
1364
1365    ci.md = md;
1366    ci.io = alloc_io(md);
1367    ci.io->error = 0;
1368    atomic_set(&ci.io->io_count, 1);
1369    ci.io->bio = bio;
1370    ci.io->md = md;
1371    spin_lock_init(&ci.io->endio_lock);
1372    ci.sector = bio->bi_sector;
1373    ci.idx = bio->bi_idx;
1374
1375    start_io_acct(ci.io);
1376
1377    if (bio->bi_rw & REQ_FLUSH) {
1378        ci.bio = &ci.md->flush_bio;
1379        ci.sector_count = 0;
1380        error = __send_empty_flush(&ci);
1381        /* dec_pending submits any data associated with flush */
1382    } else {
1383        ci.bio = bio;
1384        ci.sector_count = bio_sectors(bio);
1385        while (ci.sector_count && !error)
1386            error = __split_and_process_non_flush(&ci);
1387    }
1388
1389    /* drop the extra reference count */
1390    dec_pending(ci.io, error);
1391    dm_table_put(ci.map);
1392}
1393/*-----------------------------------------------------------------
1394 * CRUD END
1395 *---------------------------------------------------------------*/
1396
1397static int dm_merge_bvec(struct request_queue *q,
1398             struct bvec_merge_data *bvm,
1399             struct bio_vec *biovec)
1400{
1401    struct mapped_device *md = q->queuedata;
1402    struct dm_table *map = dm_get_live_table(md);
1403    struct dm_target *ti;
1404    sector_t max_sectors;
1405    int max_size = 0;
1406
1407    if (unlikely(!map))
1408        goto out;
1409
1410    ti = dm_table_find_target(map, bvm->bi_sector);
1411    if (!dm_target_is_valid(ti))
1412        goto out_table;
1413
1414    /*
1415     * Find maximum amount of I/O that won't need splitting
1416     */
1417    max_sectors = min(max_io_len(bvm->bi_sector, ti),
1418              (sector_t) BIO_MAX_SECTORS);
1419    max_size = (max_sectors << SECTOR_SHIFT) - bvm->bi_size;
1420    if (max_size < 0)
1421        max_size = 0;
1422
1423    /*
1424     * merge_bvec_fn() returns number of bytes
1425     * it can accept at this offset
1426     * max is precomputed maximal io size
1427     */
1428    if (max_size && ti->type->merge)
1429        max_size = ti->type->merge(ti, bvm, biovec, max_size);
1430    /*
1431     * If the target doesn't support merge method and some of the devices
1432     * provided their merge_bvec method (we know this by looking at
1433     * queue_max_hw_sectors), then we can't allow bios with multiple vector
1434     * entries. So always set max_size to 0, and the code below allows
1435     * just one page.
1436     */
1437    else if (queue_max_hw_sectors(q) <= PAGE_SIZE >> 9)
1438
1439        max_size = 0;
1440
1441out_table:
1442    dm_table_put(map);
1443
1444out:
1445    /*
1446     * Always allow an entire first page
1447     */
1448    if (max_size <= biovec->bv_len && !(bvm->bi_size >> SECTOR_SHIFT))
1449        max_size = biovec->bv_len;
1450
1451    return max_size;
1452}
1453
1454/*
1455 * The request function that just remaps the bio built up by
1456 * dm_merge_bvec.
1457 */
1458static void _dm_request(struct request_queue *q, struct bio *bio)
1459{
1460    int rw = bio_data_dir(bio);
1461    struct mapped_device *md = q->queuedata;
1462    int cpu;
1463
1464    down_read(&md->io_lock);
1465
1466    cpu = part_stat_lock();
1467    part_stat_inc(cpu, &dm_disk(md)->part0, ios[rw]);
1468    part_stat_add(cpu, &dm_disk(md)->part0, sectors[rw], bio_sectors(bio));
1469    part_stat_unlock();
1470
1471    /* if we're suspended, we have to queue this io for later */
1472    if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags))) {
1473        up_read(&md->io_lock);
1474
1475        if (bio_rw(bio) != READA)
1476            queue_io(md, bio);
1477        else
1478            bio_io_error(bio);
1479        return;
1480    }
1481
1482    __split_and_process_bio(md, bio);
1483    up_read(&md->io_lock);
1484    return;
1485}
1486
1487static int dm_request_based(struct mapped_device *md)
1488{
1489    return blk_queue_stackable(md->queue);
1490}
1491
1492static void dm_request(struct request_queue *q, struct bio *bio)
1493{
1494    struct mapped_device *md = q->queuedata;
1495
1496    if (dm_request_based(md))
1497        blk_queue_bio(q, bio);
1498    else
1499        _dm_request(q, bio);
1500}
1501
1502void dm_dispatch_request(struct request *rq)
1503{
1504    int r;
1505
1506    if (blk_queue_io_stat(rq->q))
1507        rq->cmd_flags |= REQ_IO_STAT;
1508
1509    rq->start_time = jiffies;
1510    r = blk_insert_cloned_request(rq->q, rq);
1511    if (r)
1512        dm_complete_request(rq, r);
1513}
1514EXPORT_SYMBOL_GPL(dm_dispatch_request);
1515
1516static int dm_rq_bio_constructor(struct bio *bio, struct bio *bio_orig,
1517                 void *data)
1518{
1519    struct dm_rq_target_io *tio = data;
1520    struct dm_rq_clone_bio_info *info =
1521        container_of(bio, struct dm_rq_clone_bio_info, clone);
1522
1523    info->orig = bio_orig;
1524    info->tio = tio;
1525    bio->bi_end_io = end_clone_bio;
1526    bio->bi_private = info;
1527
1528    return 0;
1529}
1530
1531static int setup_clone(struct request *clone, struct request *rq,
1532               struct dm_rq_target_io *tio)
1533{
1534    int r;
1535
1536    r = blk_rq_prep_clone(clone, rq, tio->md->bs, GFP_ATOMIC,
1537                  dm_rq_bio_constructor, tio);
1538    if (r)
1539        return r;
1540
1541    clone->cmd = rq->cmd;
1542    clone->cmd_len = rq->cmd_len;
1543    clone->sense = rq->sense;
1544    clone->buffer = rq->buffer;
1545    clone->end_io = end_clone_request;
1546    clone->end_io_data = tio;
1547
1548    return 0;
1549}
1550
1551static struct request *clone_rq(struct request *rq, struct mapped_device *md,
1552                gfp_t gfp_mask)
1553{
1554    struct request *clone;
1555    struct dm_rq_target_io *tio;
1556
1557    tio = alloc_rq_tio(md, gfp_mask);
1558    if (!tio)
1559        return NULL;
1560
1561    tio->md = md;
1562    tio->ti = NULL;
1563    tio->orig = rq;
1564    tio->error = 0;
1565    memset(&tio->info, 0, sizeof(tio->info));
1566
1567    clone = &tio->clone;
1568    if (setup_clone(clone, rq, tio)) {
1569        /* -ENOMEM */
1570        free_rq_tio(tio);
1571        return NULL;
1572    }
1573
1574    return clone;
1575}
1576
1577/*
1578 * Called with the queue lock held.
1579 */
1580static int dm_prep_fn(struct request_queue *q, struct request *rq)
1581{
1582    struct mapped_device *md = q->queuedata;
1583    struct request *clone;
1584
1585    if (unlikely(rq->special)) {
1586        DMWARN("Already has something in rq->special.");
1587        return BLKPREP_KILL;
1588    }
1589
1590    clone = clone_rq(rq, md, GFP_ATOMIC);
1591    if (!clone)
1592        return BLKPREP_DEFER;
1593
1594    rq->special = clone;
1595    rq->cmd_flags |= REQ_DONTPREP;
1596
1597    return BLKPREP_OK;
1598}
1599
1600/*
1601 * Returns:
1602 * 0 : the request has been processed (not requeued)
1603 * !0 : the request has been requeued
1604 */
1605static int map_request(struct dm_target *ti, struct request *clone,
1606               struct mapped_device *md)
1607{
1608    int r, requeued = 0;
1609    struct dm_rq_target_io *tio = clone->end_io_data;
1610
1611    tio->ti = ti;
1612    r = ti->type->map_rq(ti, clone, &tio->info);
1613    switch (r) {
1614    case DM_MAPIO_SUBMITTED:
1615        /* The target has taken the I/O to submit by itself later */
1616        break;
1617    case DM_MAPIO_REMAPPED:
1618        /* The target has remapped the I/O so dispatch it */
1619        trace_block_rq_remap(clone->q, clone, disk_devt(dm_disk(md)),
1620                     blk_rq_pos(tio->orig));
1621        dm_dispatch_request(clone);
1622        break;
1623    case DM_MAPIO_REQUEUE:
1624        /* The target wants to requeue the I/O */
1625        dm_requeue_unmapped_request(clone);
1626        requeued = 1;
1627        break;
1628    default:
1629        if (r > 0) {
1630            DMWARN("unimplemented target map return value: %d", r);
1631            BUG();
1632        }
1633
1634        /* The target wants to complete the I/O */
1635        dm_kill_unmapped_request(clone, r);
1636        break;
1637    }
1638
1639    return requeued;
1640}
1641
1642static struct request *dm_start_request(struct mapped_device *md, struct request *orig)
1643{
1644    struct request *clone;
1645
1646    blk_start_request(orig);
1647    clone = orig->special;
1648    atomic_inc(&md->pending[rq_data_dir(clone)]);
1649
1650    /*
1651     * Hold the md reference here for the in-flight I/O.
1652     * We can't rely on the reference count by device opener,
1653     * because the device may be closed during the request completion
1654     * when all bios are completed.
1655     * See the comment in rq_completed() too.
1656     */
1657    dm_get(md);
1658
1659    return clone;
1660}
1661
1662/*
1663 * q->request_fn for request-based dm.
1664 * Called with the queue lock held.
1665 */
1666static void dm_request_fn(struct request_queue *q)
1667{
1668    struct mapped_device *md = q->queuedata;
1669    struct dm_table *map = dm_get_live_table(md);
1670    struct dm_target *ti;
1671    struct request *rq, *clone;
1672    sector_t pos;
1673
1674    /*
1675     * For suspend, check blk_queue_stopped() and increment
1676     * ->pending within a single queue_lock not to increment the
1677     * number of in-flight I/Os after the queue is stopped in
1678     * dm_suspend().
1679     */
1680    while (!blk_queue_stopped(q)) {
1681        rq = blk_peek_request(q);
1682        if (!rq)
1683            goto delay_and_out;
1684
1685        /* always use block 0 to find the target for flushes for now */
1686        pos = 0;
1687        if (!(rq->cmd_flags & REQ_FLUSH))
1688            pos = blk_rq_pos(rq);
1689
1690        ti = dm_table_find_target(map, pos);
1691        if (!dm_target_is_valid(ti)) {
1692            /*
1693             * Must perform setup, that dm_done() requires,
1694             * before calling dm_kill_unmapped_request
1695             */
1696            DMERR_LIMIT("request attempted access beyond the end of device");
1697            clone = dm_start_request(md, rq);
1698            dm_kill_unmapped_request(clone, -EIO);
1699            continue;
1700        }
1701
1702        if (ti->type->busy && ti->type->busy(ti))
1703            goto delay_and_out;
1704
1705        clone = dm_start_request(md, rq);
1706
1707        spin_unlock(q->queue_lock);
1708        if (map_request(ti, clone, md))
1709            goto requeued;
1710
1711        BUG_ON(!irqs_disabled());
1712        spin_lock(q->queue_lock);
1713    }
1714
1715    goto out;
1716
1717requeued:
1718    BUG_ON(!irqs_disabled());
1719    spin_lock(q->queue_lock);
1720
1721delay_and_out:
1722    blk_delay_queue(q, HZ / 10);
1723out:
1724    dm_table_put(map);
1725}
1726
1727int dm_underlying_device_busy(struct request_queue *q)
1728{
1729    return blk_lld_busy(q);
1730}
1731EXPORT_SYMBOL_GPL(dm_underlying_device_busy);
1732
1733static int dm_lld_busy(struct request_queue *q)
1734{
1735    int r;
1736    struct mapped_device *md = q->queuedata;
1737    struct dm_table *map = dm_get_live_table(md);
1738
1739    if (!map || test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags))
1740        r = 1;
1741    else
1742        r = dm_table_any_busy_target(map);
1743
1744    dm_table_put(map);
1745
1746    return r;
1747}
1748
1749static int dm_any_congested(void *congested_data, int bdi_bits)
1750{
1751    int r = bdi_bits;
1752    struct mapped_device *md = congested_data;
1753    struct dm_table *map;
1754
1755    if (!test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) {
1756        map = dm_get_live_table(md);
1757        if (map) {
1758            /*
1759             * Request-based dm cares about only own queue for
1760             * the query about congestion status of request_queue
1761             */
1762            if (dm_request_based(md))
1763                r = md->queue->backing_dev_info.state &
1764                    bdi_bits;
1765            else
1766                r = dm_table_any_congested(map, bdi_bits);
1767
1768            dm_table_put(map);
1769        }
1770    }
1771
1772    return r;
1773}
1774
1775/*-----------------------------------------------------------------
1776 * An IDR is used to keep track of allocated minor numbers.
1777 *---------------------------------------------------------------*/
1778static void free_minor(int minor)
1779{
1780    spin_lock(&_minor_lock);
1781    idr_remove(&_minor_idr, minor);
1782    spin_unlock(&_minor_lock);
1783}
1784
1785/*
1786 * See if the device with a specific minor # is free.
1787 */
1788static int specific_minor(int minor)
1789{
1790    int r;
1791
1792    if (minor >= (1 << MINORBITS))
1793        return -EINVAL;
1794
1795    idr_preload(GFP_KERNEL);
1796    spin_lock(&_minor_lock);
1797
1798    r = idr_alloc(&_minor_idr, MINOR_ALLOCED, minor, minor + 1, GFP_NOWAIT);
1799
1800    spin_unlock(&_minor_lock);
1801    idr_preload_end();
1802    if (r < 0)
1803        return r == -ENOSPC ? -EBUSY : r;
1804    return 0;
1805}
1806
1807static int next_free_minor(int *minor)
1808{
1809    int r;
1810
1811    idr_preload(GFP_KERNEL);
1812    spin_lock(&_minor_lock);
1813
1814    r = idr_alloc(&_minor_idr, MINOR_ALLOCED, 0, 1 << MINORBITS, GFP_NOWAIT);
1815
1816    spin_unlock(&_minor_lock);
1817    idr_preload_end();
1818    if (r < 0)
1819        return r;
1820    *minor = r;
1821    return 0;
1822}
1823
1824static const struct block_device_operations dm_blk_dops;
1825
1826static void dm_wq_work(struct work_struct *work);
1827
1828static void dm_init_md_queue(struct mapped_device *md)
1829{
1830    /*
1831     * Request-based dm devices cannot be stacked on top of bio-based dm
1832     * devices. The type of this dm device has not been decided yet.
1833     * The type is decided at the first table loading time.
1834     * To prevent problematic device stacking, clear the queue flag
1835     * for request stacking support until then.
1836     *
1837     * This queue is new, so no concurrency on the queue_flags.
1838     */
1839    queue_flag_clear_unlocked(QUEUE_FLAG_STACKABLE, md->queue);
1840
1841    md->queue->queuedata = md;
1842    md->queue->backing_dev_info.congested_fn = dm_any_congested;
1843    md->queue->backing_dev_info.congested_data = md;
1844    blk_queue_make_request(md->queue, dm_request);
1845    blk_queue_bounce_limit(md->queue, BLK_BOUNCE_ANY);
1846    blk_queue_merge_bvec(md->queue, dm_merge_bvec);
1847}
1848
1849/*
1850 * Allocate and initialise a blank device with a given minor.
1851 */
1852static struct mapped_device *alloc_dev(int minor)
1853{
1854    int r;
1855    struct mapped_device *md = kzalloc(sizeof(*md), GFP_KERNEL);
1856    void *old_md;
1857
1858    if (!md) {
1859        DMWARN("unable to allocate device, out of memory.");
1860        return NULL;
1861    }
1862
1863    if (!try_module_get(THIS_MODULE))
1864        goto bad_module_get;
1865
1866    /* get a minor number for the dev */
1867    if (minor == DM_ANY_MINOR)
1868        r = next_free_minor(&minor);
1869    else
1870        r = specific_minor(minor);
1871    if (r < 0)
1872        goto bad_minor;
1873
1874    md->type = DM_TYPE_NONE;
1875    init_rwsem(&md->io_lock);
1876    mutex_init(&md->suspend_lock);
1877    mutex_init(&md->type_lock);
1878    spin_lock_init(&md->deferred_lock);
1879    rwlock_init(&md->map_lock);
1880    atomic_set(&md->holders, 1);
1881    atomic_set(&md->open_count, 0);
1882    atomic_set(&md->event_nr, 0);
1883    atomic_set(&md->uevent_seq, 0);
1884    INIT_LIST_HEAD(&md->uevent_list);
1885    spin_lock_init(&md->uevent_lock);
1886
1887    md->queue = blk_alloc_queue(GFP_KERNEL);
1888    if (!md->queue)
1889        goto bad_queue;
1890
1891    dm_init_md_queue(md);
1892
1893    md->disk = alloc_disk(1);
1894    if (!md->disk)
1895        goto bad_disk;
1896
1897    atomic_set(&md->pending[0], 0);
1898    atomic_set(&md->pending[1], 0);
1899    init_waitqueue_head(&md->wait);
1900    INIT_WORK(&md->work, dm_wq_work);
1901    init_waitqueue_head(&md->eventq);
1902
1903    md->disk->major = _major;
1904    md->disk->first_minor = minor;
1905    md->disk->fops = &dm_blk_dops;
1906    md->disk->queue = md->queue;
1907    md->disk->private_data = md;
1908    sprintf(md->disk->disk_name, "dm-%d", minor);
1909    add_disk(md->disk);
1910    format_dev_t(md->name, MKDEV(_major, minor));
1911
1912    md->wq = alloc_workqueue("kdmflush",
1913                 WQ_NON_REENTRANT | WQ_MEM_RECLAIM, 0);
1914    if (!md->wq)
1915        goto bad_thread;
1916
1917    md->bdev = bdget_disk(md->disk, 0);
1918    if (!md->bdev)
1919        goto bad_bdev;
1920
1921    bio_init(&md->flush_bio);
1922    md->flush_bio.bi_bdev = md->bdev;
1923    md->flush_bio.bi_rw = WRITE_FLUSH;
1924
1925    /* Populate the mapping, nobody knows we exist yet */
1926    spin_lock(&_minor_lock);
1927    old_md = idr_replace(&_minor_idr, md, minor);
1928    spin_unlock(&_minor_lock);
1929
1930    BUG_ON(old_md != MINOR_ALLOCED);
1931
1932    return md;
1933
1934bad_bdev:
1935    destroy_workqueue(md->wq);
1936bad_thread:
1937    del_gendisk(md->disk);
1938    put_disk(md->disk);
1939bad_disk:
1940    blk_cleanup_queue(md->queue);
1941bad_queue:
1942    free_minor(minor);
1943bad_minor:
1944    module_put(THIS_MODULE);
1945bad_module_get:
1946    kfree(md);
1947    return NULL;
1948}
1949
1950static void unlock_fs(struct mapped_device *md);
1951
1952static void free_dev(struct mapped_device *md)
1953{
1954    int minor = MINOR(disk_devt(md->disk));
1955
1956    unlock_fs(md);
1957    bdput(md->bdev);
1958    destroy_workqueue(md->wq);
1959    if (md->io_pool)
1960        mempool_destroy(md->io_pool);
1961    if (md->bs)
1962        bioset_free(md->bs);
1963    blk_integrity_unregister(md->disk);
1964    del_gendisk(md->disk);
1965    free_minor(minor);
1966
1967    spin_lock(&_minor_lock);
1968    md->disk->private_data = NULL;
1969    spin_unlock(&_minor_lock);
1970
1971    put_disk(md->disk);
1972    blk_cleanup_queue(md->queue);
1973    module_put(THIS_MODULE);
1974    kfree(md);
1975}
1976
1977static void __bind_mempools(struct mapped_device *md, struct dm_table *t)
1978{
1979    struct dm_md_mempools *p = dm_table_get_md_mempools(t);
1980
1981    if (md->io_pool && md->bs) {
1982        /* The md already has necessary mempools. */
1983        if (dm_table_get_type(t) == DM_TYPE_BIO_BASED) {
1984            /*
1985             * Reload bioset because front_pad may have changed
1986             * because a different table was loaded.
1987             */
1988            bioset_free(md->bs);
1989            md->bs = p->bs;
1990            p->bs = NULL;
1991        } else if (dm_table_get_type(t) == DM_TYPE_REQUEST_BASED) {
1992            /*
1993             * There's no need to reload with request-based dm
1994             * because the size of front_pad doesn't change.
1995             * Note for future: If you are to reload bioset,
1996             * prep-ed requests in the queue may refer
1997             * to bio from the old bioset, so you must walk
1998             * through the queue to unprep.
1999             */
2000        }
2001        goto out;
2002    }
2003
2004    BUG_ON(!p || md->io_pool || md->bs);
2005
2006    md->io_pool = p->io_pool;
2007    p->io_pool = NULL;
2008    md->bs = p->bs;
2009    p->bs = NULL;
2010
2011out:
2012    /* mempool bind completed, now no need any mempools in the table */
2013    dm_table_free_md_mempools(t);
2014}
2015
2016/*
2017 * Bind a table to the device.
2018 */
2019static void event_callback(void *context)
2020{
2021    unsigned long flags;
2022    LIST_HEAD(uevents);
2023    struct mapped_device *md = (struct mapped_device *) context;
2024
2025    spin_lock_irqsave(&md->uevent_lock, flags);
2026    list_splice_init(&md->uevent_list, &uevents);
2027    spin_unlock_irqrestore(&md->uevent_lock, flags);
2028
2029    dm_send_uevents(&uevents, &disk_to_dev(md->disk)->kobj);
2030
2031    atomic_inc(&md->event_nr);
2032    wake_up(&md->eventq);
2033}
2034
2035/*
2036 * Protected by md->suspend_lock obtained by dm_swap_table().
2037 */
2038static void __set_size(struct mapped_device *md, sector_t size)
2039{
2040    set_capacity(md->disk, size);
2041
2042    i_size_write(md->bdev->bd_inode, (loff_t)size << SECTOR_SHIFT);
2043}
2044
2045/*
2046 * Return 1 if the queue has a compulsory merge_bvec_fn function.
2047 *
2048 * If this function returns 0, then the device is either a non-dm
2049 * device without a merge_bvec_fn, or it is a dm device that is
2050 * able to split any bios it receives that are too big.
2051 */
2052int dm_queue_merge_is_compulsory(struct request_queue *q)
2053{
2054    struct mapped_device *dev_md;
2055
2056    if (!q->merge_bvec_fn)
2057        return 0;
2058
2059    if (q->make_request_fn == dm_request) {
2060        dev_md = q->queuedata;
2061        if (test_bit(DMF_MERGE_IS_OPTIONAL, &dev_md->flags))
2062            return 0;
2063    }
2064
2065    return 1;
2066}
2067
2068static int dm_device_merge_is_compulsory(struct dm_target *ti,
2069                     struct dm_dev *dev, sector_t start,
2070                     sector_t len, void *data)
2071{
2072    struct block_device *bdev = dev->bdev;
2073    struct request_queue *q = bdev_get_queue(bdev);
2074
2075    return dm_queue_merge_is_compulsory(q);
2076}
2077
2078/*
2079 * Return 1 if it is acceptable to ignore merge_bvec_fn based
2080 * on the properties of the underlying devices.
2081 */
2082static int dm_table_merge_is_optional(struct dm_table *table)
2083{
2084    unsigned i = 0;
2085    struct dm_target *ti;
2086
2087    while (i < dm_table_get_num_targets(table)) {
2088        ti = dm_table_get_target(table, i++);
2089
2090        if (ti->type->iterate_devices &&
2091            ti->type->iterate_devices(ti, dm_device_merge_is_compulsory, NULL))
2092            return 0;
2093    }
2094
2095    return 1;
2096}
2097
2098/*
2099 * Returns old map, which caller must destroy.
2100 */
2101static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
2102                   struct queue_limits *limits)
2103{
2104    struct dm_table *old_map;
2105    struct request_queue *q = md->queue;
2106    sector_t size;
2107    unsigned long flags;
2108    int merge_is_optional;
2109
2110    size = dm_table_get_size(t);
2111
2112    /*
2113     * Wipe any geometry if the size of the table changed.
2114     */
2115    if (size != get_capacity(md->disk))
2116        memset(&md->geometry, 0, sizeof(md->geometry));
2117
2118    __set_size(md, size);
2119
2120    dm_table_event_callback(t, event_callback, md);
2121
2122    /*
2123     * The queue hasn't been stopped yet, if the old table type wasn't
2124     * for request-based during suspension. So stop it to prevent
2125     * I/O mapping before resume.
2126     * This must be done before setting the queue restrictions,
2127     * because request-based dm may be run just after the setting.
2128     */
2129    if (dm_table_request_based(t) && !blk_queue_stopped(q))
2130        stop_queue(q);
2131
2132    __bind_mempools(md, t);
2133
2134    merge_is_optional = dm_table_merge_is_optional(t);
2135
2136    write_lock_irqsave(&md->map_lock, flags);
2137    old_map = md->map;
2138    md->map = t;
2139    md->immutable_target_type = dm_table_get_immutable_target_type(t);
2140
2141    dm_table_set_restrictions(t, q, limits);
2142    if (merge_is_optional)
2143        set_bit(DMF_MERGE_IS_OPTIONAL, &md->flags);
2144    else
2145        clear_bit(DMF_MERGE_IS_OPTIONAL, &md->flags);
2146    write_unlock_irqrestore(&md->map_lock, flags);
2147
2148    return old_map;
2149}
2150
2151/*
2152 * Returns unbound table for the caller to free.
2153 */
2154static struct dm_table *__unbind(struct mapped_device *md)
2155{
2156    struct dm_table *map = md->map;
2157    unsigned long flags;
2158
2159    if (!map)
2160        return NULL;
2161
2162    dm_table_event_callback(map, NULL, NULL);
2163    write_lock_irqsave(&md->map_lock, flags);
2164    md->map = NULL;
2165    write_unlock_irqrestore(&md->map_lock, flags);
2166
2167    return map;
2168}
2169
2170/*
2171 * Constructor for a new device.
2172 */
2173int dm_create(int minor, struct mapped_device **result)
2174{
2175    struct mapped_device *md;
2176
2177    md = alloc_dev(minor);
2178    if (!md)
2179        return -ENXIO;
2180
2181    dm_sysfs_init(md);
2182
2183    *result = md;
2184    return 0;
2185}
2186
2187/*
2188 * Functions to manage md->type.
2189 * All are required to hold md->type_lock.
2190 */
2191void dm_lock_md_type(struct mapped_device *md)
2192{
2193    mutex_lock(&md->type_lock);
2194}
2195
2196void dm_unlock_md_type(struct mapped_device *md)
2197{
2198    mutex_unlock(&md->type_lock);
2199}
2200
2201void dm_set_md_type(struct mapped_device *md, unsigned type)
2202{
2203    md->type = type;
2204}
2205
2206unsigned dm_get_md_type(struct mapped_device *md)
2207{
2208    return md->type;
2209}
2210
2211struct target_type *dm_get_immutable_target_type(struct mapped_device *md)
2212{
2213    return md->immutable_target_type;
2214}
2215
2216/*
2217 * Fully initialize a request-based queue (->elevator, ->request_fn, etc).
2218 */
2219static int dm_init_request_based_queue(struct mapped_device *md)
2220{
2221    struct request_queue *q = NULL;
2222
2223    if (md->queue->elevator)
2224        return 1;
2225
2226    /* Fully initialize the queue */
2227    q = blk_init_allocated_queue(md->queue, dm_request_fn, NULL);
2228    if (!q)
2229        return 0;
2230
2231    md->queue = q;
2232    dm_init_md_queue(md);
2233    blk_queue_softirq_done(md->queue, dm_softirq_done);
2234    blk_queue_prep_rq(md->queue, dm_prep_fn);
2235    blk_queue_lld_busy(md->queue, dm_lld_busy);
2236
2237    elv_register_queue(md->queue);
2238
2239    return 1;
2240}
2241
2242/*
2243 * Setup the DM device's queue based on md's type
2244 */
2245int dm_setup_md_queue(struct mapped_device *md)
2246{
2247    if ((dm_get_md_type(md) == DM_TYPE_REQUEST_BASED) &&
2248        !dm_init_request_based_queue(md)) {
2249        DMWARN("Cannot initialize queue for request-based mapped device");
2250        return -EINVAL;
2251    }
2252
2253    return 0;
2254}
2255
2256static struct mapped_device *dm_find_md(dev_t dev)
2257{
2258    struct mapped_device *md;
2259    unsigned minor = MINOR(dev);
2260
2261    if (MAJOR(dev) != _major || minor >= (1 << MINORBITS))
2262        return NULL;
2263
2264    spin_lock(&_minor_lock);
2265
2266    md = idr_find(&_minor_idr, minor);
2267    if (md && (md == MINOR_ALLOCED ||
2268           (MINOR(disk_devt(dm_disk(md))) != minor) ||
2269           dm_deleting_md(md) ||
2270           test_bit(DMF_FREEING, &md->flags))) {
2271        md = NULL;
2272        goto out;
2273    }
2274
2275out:
2276    spin_unlock(&_minor_lock);
2277
2278    return md;
2279}
2280
2281struct mapped_device *dm_get_md(dev_t dev)
2282{
2283    struct mapped_device *md = dm_find_md(dev);
2284
2285    if (md)
2286        dm_get(md);
2287
2288    return md;
2289}
2290EXPORT_SYMBOL_GPL(dm_get_md);
2291
2292void *dm_get_mdptr(struct mapped_device *md)
2293{
2294    return md->interface_ptr;
2295}
2296
2297void dm_set_mdptr(struct mapped_device *md, void *ptr)
2298{
2299    md->interface_ptr = ptr;
2300}
2301
2302void dm_get(struct mapped_device *md)
2303{
2304    atomic_inc(&md->holders);
2305    BUG_ON(test_bit(DMF_FREEING, &md->flags));
2306}
2307
2308const char *dm_device_name(struct mapped_device *md)
2309{
2310    return md->name;
2311}
2312EXPORT_SYMBOL_GPL(dm_device_name);
2313
2314static void __dm_destroy(struct mapped_device *md, bool wait)
2315{
2316    struct dm_table *map;
2317
2318    might_sleep();
2319
2320    spin_lock(&_minor_lock);
2321    map = dm_get_live_table(md);
2322    idr_replace(&_minor_idr, MINOR_ALLOCED, MINOR(disk_devt(dm_disk(md))));
2323    set_bit(DMF_FREEING, &md->flags);
2324    spin_unlock(&_minor_lock);
2325
2326    if (!dm_suspended_md(md)) {
2327        dm_table_presuspend_targets(map);
2328        dm_table_postsuspend_targets(map);
2329    }
2330
2331    /*
2332     * Rare, but there may be I/O requests still going to complete,
2333     * for example. Wait for all references to disappear.
2334     * No one should increment the reference count of the mapped_device,
2335     * after the mapped_device state becomes DMF_FREEING.
2336     */
2337    if (wait)
2338        while (atomic_read(&md->holders))
2339            msleep(1);
2340    else if (atomic_read(&md->holders))
2341        DMWARN("%s: Forcibly removing mapped_device still in use! (%d users)",
2342               dm_device_name(md), atomic_read(&md->holders));
2343
2344    dm_sysfs_exit(md);
2345    dm_table_put(map);
2346    dm_table_destroy(__unbind(md));
2347    free_dev(md);
2348}
2349
2350void dm_destroy(struct mapped_device *md)
2351{
2352    __dm_destroy(md, true);
2353}
2354
2355void dm_destroy_immediate(struct mapped_device *md)
2356{
2357    __dm_destroy(md, false);
2358}
2359
2360void dm_put(struct mapped_device *md)
2361{
2362    atomic_dec(&md->holders);
2363}
2364EXPORT_SYMBOL_GPL(dm_put);
2365
2366static int dm_wait_for_completion(struct mapped_device *md, int interruptible)
2367{
2368    int r = 0;
2369    DECLARE_WAITQUEUE(wait, current);
2370
2371    add_wait_queue(&md->wait, &wait);
2372
2373    while (1) {
2374        set_current_state(interruptible);
2375
2376        if (!md_in_flight(md))
2377            break;
2378
2379        if (interruptible == TASK_INTERRUPTIBLE &&
2380            signal_pending(current)) {
2381            r = -EINTR;
2382            break;
2383        }
2384
2385        io_schedule();
2386    }
2387    set_current_state(TASK_RUNNING);
2388
2389    remove_wait_queue(&md->wait, &wait);
2390
2391    return r;
2392}
2393
2394/*
2395 * Process the deferred bios
2396 */
2397static void dm_wq_work(struct work_struct *work)
2398{
2399    struct mapped_device *md = container_of(work, struct mapped_device,
2400                        work);
2401    struct bio *c;
2402
2403    down_read(&md->io_lock);
2404
2405    while (!test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) {
2406        spin_lock_irq(&md->deferred_lock);
2407        c = bio_list_pop(&md->deferred);
2408        spin_unlock_irq(&md->deferred_lock);
2409
2410        if (!c)
2411            break;
2412
2413        up_read(&md->io_lock);
2414
2415        if (dm_request_based(md))
2416            generic_make_request(c);
2417        else
2418            __split_and_process_bio(md, c);
2419
2420        down_read(&md->io_lock);
2421    }
2422
2423    up_read(&md->io_lock);
2424}
2425
2426static void dm_queue_flush(struct mapped_device *md)
2427{
2428    clear_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
2429    smp_mb__after_clear_bit();
2430    queue_work(md->wq, &md->work);
2431}
2432
2433/*
2434 * Swap in a new table, returning the old one for the caller to destroy.
2435 */
2436struct dm_table *dm_swap_table(struct mapped_device *md, struct dm_table *table)
2437{
2438    struct dm_table *live_map = NULL, *map = ERR_PTR(-EINVAL);
2439    struct queue_limits limits;
2440    int r;
2441
2442    mutex_lock(&md->suspend_lock);
2443
2444    /* device must be suspended */
2445    if (!dm_suspended_md(md))
2446        goto out;
2447
2448    /*
2449     * If the new table has no data devices, retain the existing limits.
2450     * This helps multipath with queue_if_no_path if all paths disappear,
2451     * then new I/O is queued based on these limits, and then some paths
2452     * reappear.
2453     */
2454    if (dm_table_has_no_data_devices(table)) {
2455        live_map = dm_get_live_table(md);
2456        if (live_map)
2457            limits = md->queue->limits;
2458        dm_table_put(live_map);
2459    }
2460
2461    if (!live_map) {
2462        r = dm_calculate_queue_limits(table, &limits);
2463        if (r) {
2464            map = ERR_PTR(r);
2465            goto out;
2466        }
2467    }
2468
2469    map = __bind(md, table, &limits);
2470
2471out:
2472    mutex_unlock(&md->suspend_lock);
2473    return map;
2474}
2475
2476/*
2477 * Functions to lock and unlock any filesystem running on the
2478 * device.
2479 */
2480static int lock_fs(struct mapped_device *md)
2481{
2482    int r;
2483
2484    WARN_ON(md->frozen_sb);
2485
2486    md->frozen_sb = freeze_bdev(md->bdev);
2487    if (IS_ERR(md->frozen_sb)) {
2488        r = PTR_ERR(md->frozen_sb);
2489        md->frozen_sb = NULL;
2490        return r;
2491    }
2492
2493    set_bit(DMF_FROZEN, &md->flags);
2494
2495    return 0;
2496}
2497
2498static void unlock_fs(struct mapped_device *md)
2499{
2500    if (!test_bit(DMF_FROZEN, &md->flags))
2501        return;
2502
2503    thaw_bdev(md->bdev, md->frozen_sb);
2504    md->frozen_sb = NULL;
2505    clear_bit(DMF_FROZEN, &md->flags);
2506}
2507
2508/*
2509 * We need to be able to change a mapping table under a mounted
2510 * filesystem. For example we might want to move some data in
2511 * the background. Before the table can be swapped with
2512 * dm_bind_table, dm_suspend must be called to flush any in
2513 * flight bios and ensure that any further io gets deferred.
2514 */
2515/*
2516 * Suspend mechanism in request-based dm.
2517 *
2518 * 1. Flush all I/Os by lock_fs() if needed.
2519 * 2. Stop dispatching any I/O by stopping the request_queue.
2520 * 3. Wait for all in-flight I/Os to be completed or requeued.
2521 *
2522 * To abort suspend, start the request_queue.
2523 */
2524int dm_suspend(struct mapped_device *md, unsigned suspend_flags)
2525{
2526    struct dm_table *map = NULL;
2527    int r = 0;
2528    int do_lockfs = suspend_flags & DM_SUSPEND_LOCKFS_FLAG ? 1 : 0;
2529    int noflush = suspend_flags & DM_SUSPEND_NOFLUSH_FLAG ? 1 : 0;
2530
2531    mutex_lock(&md->suspend_lock);
2532
2533    if (dm_suspended_md(md)) {
2534        r = -EINVAL;
2535        goto out_unlock;
2536    }
2537
2538    map = dm_get_live_table(md);
2539
2540    /*
2541     * DMF_NOFLUSH_SUSPENDING must be set before presuspend.
2542     * This flag is cleared before dm_suspend returns.
2543     */
2544    if (noflush)
2545        set_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
2546
2547    /* This does not get reverted if there's an error later. */
2548    dm_table_presuspend_targets(map);
2549
2550    /*
2551     * Flush I/O to the device.
2552     * Any I/O submitted after lock_fs() may not be flushed.
2553     * noflush takes precedence over do_lockfs.
2554     * (lock_fs() flushes I/Os and waits for them to complete.)
2555     */
2556    if (!noflush && do_lockfs) {
2557        r = lock_fs(md);
2558        if (r)
2559            goto out;
2560    }
2561
2562    /*
2563     * Here we must make sure that no processes are submitting requests
2564     * to target drivers i.e. no one may be executing
2565     * __split_and_process_bio. This is called from dm_request and
2566     * dm_wq_work.
2567     *
2568     * To get all processes out of __split_and_process_bio in dm_request,
2569     * we take the write lock. To prevent any process from reentering
2570     * __split_and_process_bio from dm_request and quiesce the thread
2571     * (dm_wq_work), we set BMF_BLOCK_IO_FOR_SUSPEND and call
2572     * flush_workqueue(md->wq).
2573     */
2574    down_write(&md->io_lock);
2575    set_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
2576    up_write(&md->io_lock);
2577
2578    /*
2579     * Stop md->queue before flushing md->wq in case request-based
2580     * dm defers requests to md->wq from md->queue.
2581     */
2582    if (dm_request_based(md))
2583        stop_queue(md->queue);
2584
2585    flush_workqueue(md->wq);
2586
2587    /*
2588     * At this point no more requests are entering target request routines.
2589     * We call dm_wait_for_completion to wait for all existing requests
2590     * to finish.
2591     */
2592    r = dm_wait_for_completion(md, TASK_INTERRUPTIBLE);
2593
2594    down_write(&md->io_lock);
2595    if (noflush)
2596        clear_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
2597    up_write(&md->io_lock);
2598
2599    /* were we interrupted ? */
2600    if (r < 0) {
2601        dm_queue_flush(md);
2602
2603        if (dm_request_based(md))
2604            start_queue(md->queue);
2605
2606        unlock_fs(md);
2607        goto out; /* pushback list is already flushed, so skip flush */
2608    }
2609
2610    /*
2611     * If dm_wait_for_completion returned 0, the device is completely
2612     * quiescent now. There is no request-processing activity. All new
2613     * requests are being added to md->deferred list.
2614     */
2615
2616    set_bit(DMF_SUSPENDED, &md->flags);
2617
2618    dm_table_postsuspend_targets(map);
2619
2620out:
2621    dm_table_put(map);
2622
2623out_unlock:
2624    mutex_unlock(&md->suspend_lock);
2625    return r;
2626}
2627
2628int dm_resume(struct mapped_device *md)
2629{
2630    int r = -EINVAL;
2631    struct dm_table *map = NULL;
2632
2633    mutex_lock(&md->suspend_lock);
2634    if (!dm_suspended_md(md))
2635        goto out;
2636
2637    map = dm_get_live_table(md);
2638    if (!map || !dm_table_get_size(map))
2639        goto out;
2640
2641    r = dm_table_resume_targets(map);
2642    if (r)
2643        goto out;
2644
2645    dm_queue_flush(md);
2646
2647    /*
2648     * Flushing deferred I/Os must be done after targets are resumed
2649     * so that mapping of targets can work correctly.
2650     * Request-based dm is queueing the deferred I/Os in its request_queue.
2651     */
2652    if (dm_request_based(md))
2653        start_queue(md->queue);
2654
2655    unlock_fs(md);
2656
2657    clear_bit(DMF_SUSPENDED, &md->flags);
2658
2659    r = 0;
2660out:
2661    dm_table_put(map);
2662    mutex_unlock(&md->suspend_lock);
2663
2664    return r;
2665}
2666
2667/*-----------------------------------------------------------------
2668 * Event notification.
2669 *---------------------------------------------------------------*/
2670int dm_kobject_uevent(struct mapped_device *md, enum kobject_action action,
2671               unsigned cookie)
2672{
2673    char udev_cookie[DM_COOKIE_LENGTH];
2674    char *envp[] = { udev_cookie, NULL };
2675
2676    if (!cookie)
2677        return kobject_uevent(&disk_to_dev(md->disk)->kobj, action);
2678    else {
2679        snprintf(udev_cookie, DM_COOKIE_LENGTH, "%s=%u",
2680             DM_COOKIE_ENV_VAR_NAME, cookie);
2681        return kobject_uevent_env(&disk_to_dev(md->disk)->kobj,
2682                      action, envp);
2683    }
2684}
2685
2686uint32_t dm_next_uevent_seq(struct mapped_device *md)
2687{
2688    return atomic_add_return(1, &md->uevent_seq);
2689}
2690
2691uint32_t dm_get_event_nr(struct mapped_device *md)
2692{
2693    return atomic_read(&md->event_nr);
2694}
2695
2696int dm_wait_event(struct mapped_device *md, int event_nr)
2697{
2698    return wait_event_interruptible(md->eventq,
2699            (event_nr != atomic_read(&md->event_nr)));
2700}
2701
2702void dm_uevent_add(struct mapped_device *md, struct list_head *elist)
2703{
2704    unsigned long flags;
2705
2706    spin_lock_irqsave(&md->uevent_lock, flags);
2707    list_add(elist, &md->uevent_list);
2708    spin_unlock_irqrestore(&md->uevent_lock, flags);
2709}
2710
2711/*
2712 * The gendisk is only valid as long as you have a reference
2713 * count on 'md'.
2714 */
2715struct gendisk *dm_disk(struct mapped_device *md)
2716{
2717    return md->disk;
2718}
2719
2720struct kobject *dm_kobject(struct mapped_device *md)
2721{
2722    return &md->kobj;
2723}
2724
2725/*
2726 * struct mapped_device should not be exported outside of dm.c
2727 * so use this check to verify that kobj is part of md structure
2728 */
2729struct mapped_device *dm_get_from_kobject(struct kobject *kobj)
2730{
2731    struct mapped_device *md;
2732
2733    md = container_of(kobj, struct mapped_device, kobj);
2734    if (&md->kobj != kobj)
2735        return NULL;
2736
2737    if (test_bit(DMF_FREEING, &md->flags) ||
2738        dm_deleting_md(md))
2739        return NULL;
2740
2741    dm_get(md);
2742    return md;
2743}
2744
2745int dm_suspended_md(struct mapped_device *md)
2746{
2747    return test_bit(DMF_SUSPENDED, &md->flags);
2748}
2749
2750int dm_suspended(struct dm_target *ti)
2751{
2752    return dm_suspended_md(dm_table_get_md(ti->table));
2753}
2754EXPORT_SYMBOL_GPL(dm_suspended);
2755
2756int dm_noflush_suspending(struct dm_target *ti)
2757{
2758    return __noflush_suspending(dm_table_get_md(ti->table));
2759}
2760EXPORT_SYMBOL_GPL(dm_noflush_suspending);
2761
2762struct dm_md_mempools *dm_alloc_md_mempools(unsigned type, unsigned integrity, unsigned per_bio_data_size)
2763{
2764    struct dm_md_mempools *pools = kzalloc(sizeof(*pools), GFP_KERNEL);
2765    struct kmem_cache *cachep;
2766    unsigned int pool_size;
2767    unsigned int front_pad;
2768
2769    if (!pools)
2770        return NULL;
2771
2772    if (type == DM_TYPE_BIO_BASED) {
2773        cachep = _io_cache;
2774        pool_size = 16;
2775        front_pad = roundup(per_bio_data_size, __alignof__(struct dm_target_io)) + offsetof(struct dm_target_io, clone);
2776    } else if (type == DM_TYPE_REQUEST_BASED) {
2777        cachep = _rq_tio_cache;
2778        pool_size = MIN_IOS;
2779        front_pad = offsetof(struct dm_rq_clone_bio_info, clone);
2780        /* per_bio_data_size is not used. See __bind_mempools(). */
2781        WARN_ON(per_bio_data_size != 0);
2782    } else
2783        goto out;
2784
2785    pools->io_pool = mempool_create_slab_pool(MIN_IOS, cachep);
2786    if (!pools->io_pool)
2787        goto out;
2788
2789    pools->bs = bioset_create(pool_size, front_pad);
2790    if (!pools->bs)
2791        goto out;
2792
2793    if (integrity && bioset_integrity_create(pools->bs, pool_size))
2794        goto out;
2795
2796    return pools;
2797
2798out:
2799    dm_free_md_mempools(pools);
2800
2801    return NULL;
2802}
2803
2804void dm_free_md_mempools(struct dm_md_mempools *pools)
2805{
2806    if (!pools)
2807        return;
2808
2809    if (pools->io_pool)
2810        mempool_destroy(pools->io_pool);
2811
2812    if (pools->bs)
2813        bioset_free(pools->bs);
2814
2815    kfree(pools);
2816}
2817
2818static const struct block_device_operations dm_blk_dops = {
2819    .open = dm_blk_open,
2820    .release = dm_blk_close,
2821    .ioctl = dm_blk_ioctl,
2822    .getgeo = dm_blk_getgeo,
2823    .owner = THIS_MODULE
2824};
2825
2826EXPORT_SYMBOL(dm_get_mapinfo);
2827
2828/*
2829 * module hooks
2830 */
2831module_init(dm_init);
2832module_exit(dm_exit);
2833
2834module_param(major, uint, 0);
2835MODULE_PARM_DESC(major, "The major number of the device mapper");
2836MODULE_DESCRIPTION(DM_NAME " driver");
2837MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
2838MODULE_LICENSE("GPL");
2839

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