Root/drivers/md/bitmap.c

1/*
2 * bitmap.c two-level bitmap (C) Peter T. Breuer (ptb@ot.uc3m.es) 2003
3 *
4 * bitmap_create - sets up the bitmap structure
5 * bitmap_destroy - destroys the bitmap structure
6 *
7 * additions, Copyright (C) 2003-2004, Paul Clements, SteelEye Technology, Inc.:
8 * - added disk storage for bitmap
9 * - changes to allow various bitmap chunk sizes
10 */
11
12/*
13 * Still to do:
14 *
15 * flush after percent set rather than just time based. (maybe both).
16 */
17
18#include <linux/blkdev.h>
19#include <linux/module.h>
20#include <linux/errno.h>
21#include <linux/slab.h>
22#include <linux/init.h>
23#include <linux/timer.h>
24#include <linux/sched.h>
25#include <linux/list.h>
26#include <linux/file.h>
27#include <linux/mount.h>
28#include <linux/buffer_head.h>
29#include <linux/seq_file.h>
30#include "md.h"
31#include "bitmap.h"
32
33static inline char *bmname(struct bitmap *bitmap)
34{
35    return bitmap->mddev ? mdname(bitmap->mddev) : "mdX";
36}
37
38/*
39 * check a page and, if necessary, allocate it (or hijack it if the alloc fails)
40 *
41 * 1) check to see if this page is allocated, if it's not then try to alloc
42 * 2) if the alloc fails, set the page's hijacked flag so we'll use the
43 * page pointer directly as a counter
44 *
45 * if we find our page, we increment the page's refcount so that it stays
46 * allocated while we're using it
47 */
48static int bitmap_checkpage(struct bitmap_counts *bitmap,
49                unsigned long page, int create)
50__releases(bitmap->lock)
51__acquires(bitmap->lock)
52{
53    unsigned char *mappage;
54
55    if (page >= bitmap->pages) {
56        /* This can happen if bitmap_start_sync goes beyond
57         * End-of-device while looking for a whole page.
58         * It is harmless.
59         */
60        return -EINVAL;
61    }
62
63    if (bitmap->bp[page].hijacked) /* it's hijacked, don't try to alloc */
64        return 0;
65
66    if (bitmap->bp[page].map) /* page is already allocated, just return */
67        return 0;
68
69    if (!create)
70        return -ENOENT;
71
72    /* this page has not been allocated yet */
73
74    spin_unlock_irq(&bitmap->lock);
75    mappage = kzalloc(PAGE_SIZE, GFP_NOIO);
76    spin_lock_irq(&bitmap->lock);
77
78    if (mappage == NULL) {
79        pr_debug("md/bitmap: map page allocation failed, hijacking\n");
80        /* failed - set the hijacked flag so that we can use the
81         * pointer as a counter */
82        if (!bitmap->bp[page].map)
83            bitmap->bp[page].hijacked = 1;
84    } else if (bitmap->bp[page].map ||
85           bitmap->bp[page].hijacked) {
86        /* somebody beat us to getting the page */
87        kfree(mappage);
88        return 0;
89    } else {
90
91        /* no page was in place and we have one, so install it */
92
93        bitmap->bp[page].map = mappage;
94        bitmap->missing_pages--;
95    }
96    return 0;
97}
98
99/* if page is completely empty, put it back on the free list, or dealloc it */
100/* if page was hijacked, unmark the flag so it might get alloced next time */
101/* Note: lock should be held when calling this */
102static void bitmap_checkfree(struct bitmap_counts *bitmap, unsigned long page)
103{
104    char *ptr;
105
106    if (bitmap->bp[page].count) /* page is still busy */
107        return;
108
109    /* page is no longer in use, it can be released */
110
111    if (bitmap->bp[page].hijacked) { /* page was hijacked, undo this now */
112        bitmap->bp[page].hijacked = 0;
113        bitmap->bp[page].map = NULL;
114    } else {
115        /* normal case, free the page */
116        ptr = bitmap->bp[page].map;
117        bitmap->bp[page].map = NULL;
118        bitmap->missing_pages++;
119        kfree(ptr);
120    }
121}
122
123/*
124 * bitmap file handling - read and write the bitmap file and its superblock
125 */
126
127/*
128 * basic page I/O operations
129 */
130
131/* IO operations when bitmap is stored near all superblocks */
132static int read_sb_page(struct mddev *mddev, loff_t offset,
133            struct page *page,
134            unsigned long index, int size)
135{
136    /* choose a good rdev and read the page from there */
137
138    struct md_rdev *rdev;
139    sector_t target;
140
141    rdev_for_each(rdev, mddev) {
142        if (! test_bit(In_sync, &rdev->flags)
143            || test_bit(Faulty, &rdev->flags))
144            continue;
145
146        target = offset + index * (PAGE_SIZE/512);
147
148        if (sync_page_io(rdev, target,
149                 roundup(size, bdev_logical_block_size(rdev->bdev)),
150                 page, READ, true)) {
151            page->index = index;
152            return 0;
153        }
154    }
155    return -EIO;
156}
157
158static struct md_rdev *next_active_rdev(struct md_rdev *rdev, struct mddev *mddev)
159{
160    /* Iterate the disks of an mddev, using rcu to protect access to the
161     * linked list, and raising the refcount of devices we return to ensure
162     * they don't disappear while in use.
163     * As devices are only added or removed when raid_disk is < 0 and
164     * nr_pending is 0 and In_sync is clear, the entries we return will
165     * still be in the same position on the list when we re-enter
166     * list_for_each_entry_continue_rcu.
167     */
168    rcu_read_lock();
169    if (rdev == NULL)
170        /* start at the beginning */
171        rdev = list_entry_rcu(&mddev->disks, struct md_rdev, same_set);
172    else {
173        /* release the previous rdev and start from there. */
174        rdev_dec_pending(rdev, mddev);
175    }
176    list_for_each_entry_continue_rcu(rdev, &mddev->disks, same_set) {
177        if (rdev->raid_disk >= 0 &&
178            !test_bit(Faulty, &rdev->flags)) {
179            /* this is a usable devices */
180            atomic_inc(&rdev->nr_pending);
181            rcu_read_unlock();
182            return rdev;
183        }
184    }
185    rcu_read_unlock();
186    return NULL;
187}
188
189static int write_sb_page(struct bitmap *bitmap, struct page *page, int wait)
190{
191    struct md_rdev *rdev = NULL;
192    struct block_device *bdev;
193    struct mddev *mddev = bitmap->mddev;
194    struct bitmap_storage *store = &bitmap->storage;
195
196    while ((rdev = next_active_rdev(rdev, mddev)) != NULL) {
197        int size = PAGE_SIZE;
198        loff_t offset = mddev->bitmap_info.offset;
199
200        bdev = (rdev->meta_bdev) ? rdev->meta_bdev : rdev->bdev;
201
202        if (page->index == store->file_pages-1) {
203            int last_page_size = store->bytes & (PAGE_SIZE-1);
204            if (last_page_size == 0)
205                last_page_size = PAGE_SIZE;
206            size = roundup(last_page_size,
207                       bdev_logical_block_size(bdev));
208        }
209        /* Just make sure we aren't corrupting data or
210         * metadata
211         */
212        if (mddev->external) {
213            /* Bitmap could be anywhere. */
214            if (rdev->sb_start + offset + (page->index
215                               * (PAGE_SIZE/512))
216                > rdev->data_offset
217                &&
218                rdev->sb_start + offset
219                < (rdev->data_offset + mddev->dev_sectors
220                 + (PAGE_SIZE/512)))
221                goto bad_alignment;
222        } else if (offset < 0) {
223            /* DATA BITMAP METADATA */
224            if (offset
225                + (long)(page->index * (PAGE_SIZE/512))
226                + size/512 > 0)
227                /* bitmap runs in to metadata */
228                goto bad_alignment;
229            if (rdev->data_offset + mddev->dev_sectors
230                > rdev->sb_start + offset)
231                /* data runs in to bitmap */
232                goto bad_alignment;
233        } else if (rdev->sb_start < rdev->data_offset) {
234            /* METADATA BITMAP DATA */
235            if (rdev->sb_start
236                + offset
237                + page->index*(PAGE_SIZE/512) + size/512
238                > rdev->data_offset)
239                /* bitmap runs in to data */
240                goto bad_alignment;
241        } else {
242            /* DATA METADATA BITMAP - no problems */
243        }
244        md_super_write(mddev, rdev,
245                   rdev->sb_start + offset
246                   + page->index * (PAGE_SIZE/512),
247                   size,
248                   page);
249    }
250
251    if (wait)
252        md_super_wait(mddev);
253    return 0;
254
255 bad_alignment:
256    return -EINVAL;
257}
258
259static void bitmap_file_kick(struct bitmap *bitmap);
260/*
261 * write out a page to a file
262 */
263static void write_page(struct bitmap *bitmap, struct page *page, int wait)
264{
265    struct buffer_head *bh;
266
267    if (bitmap->storage.file == NULL) {
268        switch (write_sb_page(bitmap, page, wait)) {
269        case -EINVAL:
270            set_bit(BITMAP_WRITE_ERROR, &bitmap->flags);
271        }
272    } else {
273
274        bh = page_buffers(page);
275
276        while (bh && bh->b_blocknr) {
277            atomic_inc(&bitmap->pending_writes);
278            set_buffer_locked(bh);
279            set_buffer_mapped(bh);
280            submit_bh(WRITE | REQ_SYNC, bh);
281            bh = bh->b_this_page;
282        }
283
284        if (wait)
285            wait_event(bitmap->write_wait,
286                   atomic_read(&bitmap->pending_writes)==0);
287    }
288    if (test_bit(BITMAP_WRITE_ERROR, &bitmap->flags))
289        bitmap_file_kick(bitmap);
290}
291
292static void end_bitmap_write(struct buffer_head *bh, int uptodate)
293{
294    struct bitmap *bitmap = bh->b_private;
295
296    if (!uptodate)
297        set_bit(BITMAP_WRITE_ERROR, &bitmap->flags);
298    if (atomic_dec_and_test(&bitmap->pending_writes))
299        wake_up(&bitmap->write_wait);
300}
301
302/* copied from buffer.c */
303static void
304__clear_page_buffers(struct page *page)
305{
306    ClearPagePrivate(page);
307    set_page_private(page, 0);
308    page_cache_release(page);
309}
310static void free_buffers(struct page *page)
311{
312    struct buffer_head *bh;
313
314    if (!PagePrivate(page))
315        return;
316
317    bh = page_buffers(page);
318    while (bh) {
319        struct buffer_head *next = bh->b_this_page;
320        free_buffer_head(bh);
321        bh = next;
322    }
323    __clear_page_buffers(page);
324    put_page(page);
325}
326
327/* read a page from a file.
328 * We both read the page, and attach buffers to the page to record the
329 * address of each block (using bmap). These addresses will be used
330 * to write the block later, completely bypassing the filesystem.
331 * This usage is similar to how swap files are handled, and allows us
332 * to write to a file with no concerns of memory allocation failing.
333 */
334static int read_page(struct file *file, unsigned long index,
335             struct bitmap *bitmap,
336             unsigned long count,
337             struct page *page)
338{
339    int ret = 0;
340    struct inode *inode = file_inode(file);
341    struct buffer_head *bh;
342    sector_t block;
343
344    pr_debug("read bitmap file (%dB @ %llu)\n", (int)PAGE_SIZE,
345         (unsigned long long)index << PAGE_SHIFT);
346
347    bh = alloc_page_buffers(page, 1<<inode->i_blkbits, 0);
348    if (!bh) {
349        ret = -ENOMEM;
350        goto out;
351    }
352    attach_page_buffers(page, bh);
353    block = index << (PAGE_SHIFT - inode->i_blkbits);
354    while (bh) {
355        if (count == 0)
356            bh->b_blocknr = 0;
357        else {
358            bh->b_blocknr = bmap(inode, block);
359            if (bh->b_blocknr == 0) {
360                /* Cannot use this file! */
361                ret = -EINVAL;
362                goto out;
363            }
364            bh->b_bdev = inode->i_sb->s_bdev;
365            if (count < (1<<inode->i_blkbits))
366                count = 0;
367            else
368                count -= (1<<inode->i_blkbits);
369
370            bh->b_end_io = end_bitmap_write;
371            bh->b_private = bitmap;
372            atomic_inc(&bitmap->pending_writes);
373            set_buffer_locked(bh);
374            set_buffer_mapped(bh);
375            submit_bh(READ, bh);
376        }
377        block++;
378        bh = bh->b_this_page;
379    }
380    page->index = index;
381
382    wait_event(bitmap->write_wait,
383           atomic_read(&bitmap->pending_writes)==0);
384    if (test_bit(BITMAP_WRITE_ERROR, &bitmap->flags))
385        ret = -EIO;
386out:
387    if (ret)
388        printk(KERN_ALERT "md: bitmap read error: (%dB @ %llu): %d\n",
389            (int)PAGE_SIZE,
390            (unsigned long long)index << PAGE_SHIFT,
391            ret);
392    return ret;
393}
394
395/*
396 * bitmap file superblock operations
397 */
398
399/* update the event counter and sync the superblock to disk */
400void bitmap_update_sb(struct bitmap *bitmap)
401{
402    bitmap_super_t *sb;
403
404    if (!bitmap || !bitmap->mddev) /* no bitmap for this array */
405        return;
406    if (bitmap->mddev->bitmap_info.external)
407        return;
408    if (!bitmap->storage.sb_page) /* no superblock */
409        return;
410    sb = kmap_atomic(bitmap->storage.sb_page);
411    sb->events = cpu_to_le64(bitmap->mddev->events);
412    if (bitmap->mddev->events < bitmap->events_cleared)
413        /* rocking back to read-only */
414        bitmap->events_cleared = bitmap->mddev->events;
415    sb->events_cleared = cpu_to_le64(bitmap->events_cleared);
416    sb->state = cpu_to_le32(bitmap->flags);
417    /* Just in case these have been changed via sysfs: */
418    sb->daemon_sleep = cpu_to_le32(bitmap->mddev->bitmap_info.daemon_sleep/HZ);
419    sb->write_behind = cpu_to_le32(bitmap->mddev->bitmap_info.max_write_behind);
420    /* This might have been changed by a reshape */
421    sb->sync_size = cpu_to_le64(bitmap->mddev->resync_max_sectors);
422    sb->chunksize = cpu_to_le32(bitmap->mddev->bitmap_info.chunksize);
423    sb->sectors_reserved = cpu_to_le32(bitmap->mddev->
424                       bitmap_info.space);
425    kunmap_atomic(sb);
426    write_page(bitmap, bitmap->storage.sb_page, 1);
427}
428
429/* print out the bitmap file superblock */
430void bitmap_print_sb(struct bitmap *bitmap)
431{
432    bitmap_super_t *sb;
433
434    if (!bitmap || !bitmap->storage.sb_page)
435        return;
436    sb = kmap_atomic(bitmap->storage.sb_page);
437    printk(KERN_DEBUG "%s: bitmap file superblock:\n", bmname(bitmap));
438    printk(KERN_DEBUG " magic: %08x\n", le32_to_cpu(sb->magic));
439    printk(KERN_DEBUG " version: %d\n", le32_to_cpu(sb->version));
440    printk(KERN_DEBUG " uuid: %08x.%08x.%08x.%08x\n",
441                    *(__u32 *)(sb->uuid+0),
442                    *(__u32 *)(sb->uuid+4),
443                    *(__u32 *)(sb->uuid+8),
444                    *(__u32 *)(sb->uuid+12));
445    printk(KERN_DEBUG " events: %llu\n",
446            (unsigned long long) le64_to_cpu(sb->events));
447    printk(KERN_DEBUG "events cleared: %llu\n",
448            (unsigned long long) le64_to_cpu(sb->events_cleared));
449    printk(KERN_DEBUG " state: %08x\n", le32_to_cpu(sb->state));
450    printk(KERN_DEBUG " chunksize: %d B\n", le32_to_cpu(sb->chunksize));
451    printk(KERN_DEBUG " daemon sleep: %ds\n", le32_to_cpu(sb->daemon_sleep));
452    printk(KERN_DEBUG " sync size: %llu KB\n",
453            (unsigned long long)le64_to_cpu(sb->sync_size)/2);
454    printk(KERN_DEBUG "max write behind: %d\n", le32_to_cpu(sb->write_behind));
455    kunmap_atomic(sb);
456}
457
458/*
459 * bitmap_new_disk_sb
460 * @bitmap
461 *
462 * This function is somewhat the reverse of bitmap_read_sb. bitmap_read_sb
463 * reads and verifies the on-disk bitmap superblock and populates bitmap_info.
464 * This function verifies 'bitmap_info' and populates the on-disk bitmap
465 * structure, which is to be written to disk.
466 *
467 * Returns: 0 on success, -Exxx on error
468 */
469static int bitmap_new_disk_sb(struct bitmap *bitmap)
470{
471    bitmap_super_t *sb;
472    unsigned long chunksize, daemon_sleep, write_behind;
473
474    bitmap->storage.sb_page = alloc_page(GFP_KERNEL);
475    if (bitmap->storage.sb_page == NULL)
476        return -ENOMEM;
477    bitmap->storage.sb_page->index = 0;
478
479    sb = kmap_atomic(bitmap->storage.sb_page);
480
481    sb->magic = cpu_to_le32(BITMAP_MAGIC);
482    sb->version = cpu_to_le32(BITMAP_MAJOR_HI);
483
484    chunksize = bitmap->mddev->bitmap_info.chunksize;
485    BUG_ON(!chunksize);
486    if (!is_power_of_2(chunksize)) {
487        kunmap_atomic(sb);
488        printk(KERN_ERR "bitmap chunksize not a power of 2\n");
489        return -EINVAL;
490    }
491    sb->chunksize = cpu_to_le32(chunksize);
492
493    daemon_sleep = bitmap->mddev->bitmap_info.daemon_sleep;
494    if (!daemon_sleep ||
495        (daemon_sleep < 1) || (daemon_sleep > MAX_SCHEDULE_TIMEOUT)) {
496        printk(KERN_INFO "Choosing daemon_sleep default (5 sec)\n");
497        daemon_sleep = 5 * HZ;
498    }
499    sb->daemon_sleep = cpu_to_le32(daemon_sleep);
500    bitmap->mddev->bitmap_info.daemon_sleep = daemon_sleep;
501
502    /*
503     * FIXME: write_behind for RAID1. If not specified, what
504     * is a good choice? We choose COUNTER_MAX / 2 arbitrarily.
505     */
506    write_behind = bitmap->mddev->bitmap_info.max_write_behind;
507    if (write_behind > COUNTER_MAX)
508        write_behind = COUNTER_MAX / 2;
509    sb->write_behind = cpu_to_le32(write_behind);
510    bitmap->mddev->bitmap_info.max_write_behind = write_behind;
511
512    /* keep the array size field of the bitmap superblock up to date */
513    sb->sync_size = cpu_to_le64(bitmap->mddev->resync_max_sectors);
514
515    memcpy(sb->uuid, bitmap->mddev->uuid, 16);
516
517    set_bit(BITMAP_STALE, &bitmap->flags);
518    sb->state = cpu_to_le32(bitmap->flags);
519    bitmap->events_cleared = bitmap->mddev->events;
520    sb->events_cleared = cpu_to_le64(bitmap->mddev->events);
521
522    kunmap_atomic(sb);
523
524    return 0;
525}
526
527/* read the superblock from the bitmap file and initialize some bitmap fields */
528static int bitmap_read_sb(struct bitmap *bitmap)
529{
530    char *reason = NULL;
531    bitmap_super_t *sb;
532    unsigned long chunksize, daemon_sleep, write_behind;
533    unsigned long long events;
534    unsigned long sectors_reserved = 0;
535    int err = -EINVAL;
536    struct page *sb_page;
537
538    if (!bitmap->storage.file && !bitmap->mddev->bitmap_info.offset) {
539        chunksize = 128 * 1024 * 1024;
540        daemon_sleep = 5 * HZ;
541        write_behind = 0;
542        set_bit(BITMAP_STALE, &bitmap->flags);
543        err = 0;
544        goto out_no_sb;
545    }
546    /* page 0 is the superblock, read it... */
547    sb_page = alloc_page(GFP_KERNEL);
548    if (!sb_page)
549        return -ENOMEM;
550    bitmap->storage.sb_page = sb_page;
551
552    if (bitmap->storage.file) {
553        loff_t isize = i_size_read(bitmap->storage.file->f_mapping->host);
554        int bytes = isize > PAGE_SIZE ? PAGE_SIZE : isize;
555
556        err = read_page(bitmap->storage.file, 0,
557                bitmap, bytes, sb_page);
558    } else {
559        err = read_sb_page(bitmap->mddev,
560                   bitmap->mddev->bitmap_info.offset,
561                   sb_page,
562                   0, sizeof(bitmap_super_t));
563    }
564    if (err)
565        return err;
566
567    sb = kmap_atomic(sb_page);
568
569    chunksize = le32_to_cpu(sb->chunksize);
570    daemon_sleep = le32_to_cpu(sb->daemon_sleep) * HZ;
571    write_behind = le32_to_cpu(sb->write_behind);
572    sectors_reserved = le32_to_cpu(sb->sectors_reserved);
573
574    /* verify that the bitmap-specific fields are valid */
575    if (sb->magic != cpu_to_le32(BITMAP_MAGIC))
576        reason = "bad magic";
577    else if (le32_to_cpu(sb->version) < BITMAP_MAJOR_LO ||
578         le32_to_cpu(sb->version) > BITMAP_MAJOR_HI)
579        reason = "unrecognized superblock version";
580    else if (chunksize < 512)
581        reason = "bitmap chunksize too small";
582    else if (!is_power_of_2(chunksize))
583        reason = "bitmap chunksize not a power of 2";
584    else if (daemon_sleep < 1 || daemon_sleep > MAX_SCHEDULE_TIMEOUT)
585        reason = "daemon sleep period out of range";
586    else if (write_behind > COUNTER_MAX)
587        reason = "write-behind limit out of range (0 - 16383)";
588    if (reason) {
589        printk(KERN_INFO "%s: invalid bitmap file superblock: %s\n",
590            bmname(bitmap), reason);
591        goto out;
592    }
593
594    /* keep the array size field of the bitmap superblock up to date */
595    sb->sync_size = cpu_to_le64(bitmap->mddev->resync_max_sectors);
596
597    if (bitmap->mddev->persistent) {
598        /*
599         * We have a persistent array superblock, so compare the
600         * bitmap's UUID and event counter to the mddev's
601         */
602        if (memcmp(sb->uuid, bitmap->mddev->uuid, 16)) {
603            printk(KERN_INFO
604                   "%s: bitmap superblock UUID mismatch\n",
605                   bmname(bitmap));
606            goto out;
607        }
608        events = le64_to_cpu(sb->events);
609        if (events < bitmap->mddev->events) {
610            printk(KERN_INFO
611                   "%s: bitmap file is out of date (%llu < %llu) "
612                   "-- forcing full recovery\n",
613                   bmname(bitmap), events,
614                   (unsigned long long) bitmap->mddev->events);
615            set_bit(BITMAP_STALE, &bitmap->flags);
616        }
617    }
618
619    /* assign fields using values from superblock */
620    bitmap->flags |= le32_to_cpu(sb->state);
621    if (le32_to_cpu(sb->version) == BITMAP_MAJOR_HOSTENDIAN)
622        set_bit(BITMAP_HOSTENDIAN, &bitmap->flags);
623    bitmap->events_cleared = le64_to_cpu(sb->events_cleared);
624    err = 0;
625out:
626    kunmap_atomic(sb);
627out_no_sb:
628    if (test_bit(BITMAP_STALE, &bitmap->flags))
629        bitmap->events_cleared = bitmap->mddev->events;
630    bitmap->mddev->bitmap_info.chunksize = chunksize;
631    bitmap->mddev->bitmap_info.daemon_sleep = daemon_sleep;
632    bitmap->mddev->bitmap_info.max_write_behind = write_behind;
633    if (bitmap->mddev->bitmap_info.space == 0 ||
634        bitmap->mddev->bitmap_info.space > sectors_reserved)
635        bitmap->mddev->bitmap_info.space = sectors_reserved;
636    if (err)
637        bitmap_print_sb(bitmap);
638    return err;
639}
640
641/*
642 * general bitmap file operations
643 */
644
645/*
646 * on-disk bitmap:
647 *
648 * Use one bit per "chunk" (block set). We do the disk I/O on the bitmap
649 * file a page at a time. There's a superblock at the start of the file.
650 */
651/* calculate the index of the page that contains this bit */
652static inline unsigned long file_page_index(struct bitmap_storage *store,
653                        unsigned long chunk)
654{
655    if (store->sb_page)
656        chunk += sizeof(bitmap_super_t) << 3;
657    return chunk >> PAGE_BIT_SHIFT;
658}
659
660/* calculate the (bit) offset of this bit within a page */
661static inline unsigned long file_page_offset(struct bitmap_storage *store,
662                         unsigned long chunk)
663{
664    if (store->sb_page)
665        chunk += sizeof(bitmap_super_t) << 3;
666    return chunk & (PAGE_BITS - 1);
667}
668
669/*
670 * return a pointer to the page in the filemap that contains the given bit
671 *
672 * this lookup is complicated by the fact that the bitmap sb might be exactly
673 * 1 page (e.g., x86) or less than 1 page -- so the bitmap might start on page
674 * 0 or page 1
675 */
676static inline struct page *filemap_get_page(struct bitmap_storage *store,
677                        unsigned long chunk)
678{
679    if (file_page_index(store, chunk) >= store->file_pages)
680        return NULL;
681    return store->filemap[file_page_index(store, chunk)
682                  - file_page_index(store, 0)];
683}
684
685static int bitmap_storage_alloc(struct bitmap_storage *store,
686                unsigned long chunks, int with_super)
687{
688    int pnum;
689    unsigned long num_pages;
690    unsigned long bytes;
691
692    bytes = DIV_ROUND_UP(chunks, 8);
693    if (with_super)
694        bytes += sizeof(bitmap_super_t);
695
696    num_pages = DIV_ROUND_UP(bytes, PAGE_SIZE);
697
698    store->filemap = kmalloc(sizeof(struct page *)
699                 * num_pages, GFP_KERNEL);
700    if (!store->filemap)
701        return -ENOMEM;
702
703    if (with_super && !store->sb_page) {
704        store->sb_page = alloc_page(GFP_KERNEL|__GFP_ZERO);
705        if (store->sb_page == NULL)
706            return -ENOMEM;
707        store->sb_page->index = 0;
708    }
709    pnum = 0;
710    if (store->sb_page) {
711        store->filemap[0] = store->sb_page;
712        pnum = 1;
713    }
714    for ( ; pnum < num_pages; pnum++) {
715        store->filemap[pnum] = alloc_page(GFP_KERNEL|__GFP_ZERO);
716        if (!store->filemap[pnum]) {
717            store->file_pages = pnum;
718            return -ENOMEM;
719        }
720        store->filemap[pnum]->index = pnum;
721    }
722    store->file_pages = pnum;
723
724    /* We need 4 bits per page, rounded up to a multiple
725     * of sizeof(unsigned long) */
726    store->filemap_attr = kzalloc(
727        roundup(DIV_ROUND_UP(num_pages*4, 8), sizeof(unsigned long)),
728        GFP_KERNEL);
729    if (!store->filemap_attr)
730        return -ENOMEM;
731
732    store->bytes = bytes;
733
734    return 0;
735}
736
737static void bitmap_file_unmap(struct bitmap_storage *store)
738{
739    struct page **map, *sb_page;
740    int pages;
741    struct file *file;
742
743    file = store->file;
744    map = store->filemap;
745    pages = store->file_pages;
746    sb_page = store->sb_page;
747
748    while (pages--)
749        if (map[pages] != sb_page) /* 0 is sb_page, release it below */
750            free_buffers(map[pages]);
751    kfree(map);
752    kfree(store->filemap_attr);
753
754    if (sb_page)
755        free_buffers(sb_page);
756
757    if (file) {
758        struct inode *inode = file_inode(file);
759        invalidate_mapping_pages(inode->i_mapping, 0, -1);
760        fput(file);
761    }
762}
763
764/*
765 * bitmap_file_kick - if an error occurs while manipulating the bitmap file
766 * then it is no longer reliable, so we stop using it and we mark the file
767 * as failed in the superblock
768 */
769static void bitmap_file_kick(struct bitmap *bitmap)
770{
771    char *path, *ptr = NULL;
772
773    if (!test_and_set_bit(BITMAP_STALE, &bitmap->flags)) {
774        bitmap_update_sb(bitmap);
775
776        if (bitmap->storage.file) {
777            path = kmalloc(PAGE_SIZE, GFP_KERNEL);
778            if (path)
779                ptr = d_path(&bitmap->storage.file->f_path,
780                         path, PAGE_SIZE);
781
782            printk(KERN_ALERT
783                  "%s: kicking failed bitmap file %s from array!\n",
784                  bmname(bitmap), IS_ERR(ptr) ? "" : ptr);
785
786            kfree(path);
787        } else
788            printk(KERN_ALERT
789                   "%s: disabling internal bitmap due to errors\n",
790                   bmname(bitmap));
791    }
792}
793
794enum bitmap_page_attr {
795    BITMAP_PAGE_DIRTY = 0, /* there are set bits that need to be synced */
796    BITMAP_PAGE_PENDING = 1, /* there are bits that are being cleaned.
797                    * i.e. counter is 1 or 2. */
798    BITMAP_PAGE_NEEDWRITE = 2, /* there are cleared bits that need to be synced */
799};
800
801static inline void set_page_attr(struct bitmap *bitmap, int pnum,
802                 enum bitmap_page_attr attr)
803{
804    set_bit((pnum<<2) + attr, bitmap->storage.filemap_attr);
805}
806
807static inline void clear_page_attr(struct bitmap *bitmap, int pnum,
808                   enum bitmap_page_attr attr)
809{
810    clear_bit((pnum<<2) + attr, bitmap->storage.filemap_attr);
811}
812
813static inline int test_page_attr(struct bitmap *bitmap, int pnum,
814                 enum bitmap_page_attr attr)
815{
816    return test_bit((pnum<<2) + attr, bitmap->storage.filemap_attr);
817}
818
819static inline int test_and_clear_page_attr(struct bitmap *bitmap, int pnum,
820                       enum bitmap_page_attr attr)
821{
822    return test_and_clear_bit((pnum<<2) + attr,
823                  bitmap->storage.filemap_attr);
824}
825/*
826 * bitmap_file_set_bit -- called before performing a write to the md device
827 * to set (and eventually sync) a particular bit in the bitmap file
828 *
829 * we set the bit immediately, then we record the page number so that
830 * when an unplug occurs, we can flush the dirty pages out to disk
831 */
832static void bitmap_file_set_bit(struct bitmap *bitmap, sector_t block)
833{
834    unsigned long bit;
835    struct page *page;
836    void *kaddr;
837    unsigned long chunk = block >> bitmap->counts.chunkshift;
838
839    page = filemap_get_page(&bitmap->storage, chunk);
840    if (!page)
841        return;
842    bit = file_page_offset(&bitmap->storage, chunk);
843
844    /* set the bit */
845    kaddr = kmap_atomic(page);
846    if (test_bit(BITMAP_HOSTENDIAN, &bitmap->flags))
847        set_bit(bit, kaddr);
848    else
849        test_and_set_bit_le(bit, kaddr);
850    kunmap_atomic(kaddr);
851    pr_debug("set file bit %lu page %lu\n", bit, page->index);
852    /* record page number so it gets flushed to disk when unplug occurs */
853    set_page_attr(bitmap, page->index, BITMAP_PAGE_DIRTY);
854}
855
856static void bitmap_file_clear_bit(struct bitmap *bitmap, sector_t block)
857{
858    unsigned long bit;
859    struct page *page;
860    void *paddr;
861    unsigned long chunk = block >> bitmap->counts.chunkshift;
862
863    page = filemap_get_page(&bitmap->storage, chunk);
864    if (!page)
865        return;
866    bit = file_page_offset(&bitmap->storage, chunk);
867    paddr = kmap_atomic(page);
868    if (test_bit(BITMAP_HOSTENDIAN, &bitmap->flags))
869        clear_bit(bit, paddr);
870    else
871        test_and_clear_bit_le(bit, paddr);
872    kunmap_atomic(paddr);
873    if (!test_page_attr(bitmap, page->index, BITMAP_PAGE_NEEDWRITE)) {
874        set_page_attr(bitmap, page->index, BITMAP_PAGE_PENDING);
875        bitmap->allclean = 0;
876    }
877}
878
879/* this gets called when the md device is ready to unplug its underlying
880 * (slave) device queues -- before we let any writes go down, we need to
881 * sync the dirty pages of the bitmap file to disk */
882void bitmap_unplug(struct bitmap *bitmap)
883{
884    unsigned long i;
885    int dirty, need_write;
886    int wait = 0;
887
888    if (!bitmap || !bitmap->storage.filemap ||
889        test_bit(BITMAP_STALE, &bitmap->flags))
890        return;
891
892    /* look at each page to see if there are any set bits that need to be
893     * flushed out to disk */
894    for (i = 0; i < bitmap->storage.file_pages; i++) {
895        if (!bitmap->storage.filemap)
896            return;
897        dirty = test_and_clear_page_attr(bitmap, i, BITMAP_PAGE_DIRTY);
898        need_write = test_and_clear_page_attr(bitmap, i,
899                              BITMAP_PAGE_NEEDWRITE);
900        if (dirty || need_write) {
901            clear_page_attr(bitmap, i, BITMAP_PAGE_PENDING);
902            write_page(bitmap, bitmap->storage.filemap[i], 0);
903        }
904        if (dirty)
905            wait = 1;
906    }
907    if (wait) { /* if any writes were performed, we need to wait on them */
908        if (bitmap->storage.file)
909            wait_event(bitmap->write_wait,
910                   atomic_read(&bitmap->pending_writes)==0);
911        else
912            md_super_wait(bitmap->mddev);
913    }
914    if (test_bit(BITMAP_WRITE_ERROR, &bitmap->flags))
915        bitmap_file_kick(bitmap);
916}
917EXPORT_SYMBOL(bitmap_unplug);
918
919static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset, int needed);
920/* * bitmap_init_from_disk -- called at bitmap_create time to initialize
921 * the in-memory bitmap from the on-disk bitmap -- also, sets up the
922 * memory mapping of the bitmap file
923 * Special cases:
924 * if there's no bitmap file, or if the bitmap file had been
925 * previously kicked from the array, we mark all the bits as
926 * 1's in order to cause a full resync.
927 *
928 * We ignore all bits for sectors that end earlier than 'start'.
929 * This is used when reading an out-of-date bitmap...
930 */
931static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
932{
933    unsigned long i, chunks, index, oldindex, bit;
934    struct page *page = NULL;
935    unsigned long bit_cnt = 0;
936    struct file *file;
937    unsigned long offset;
938    int outofdate;
939    int ret = -ENOSPC;
940    void *paddr;
941    struct bitmap_storage *store = &bitmap->storage;
942
943    chunks = bitmap->counts.chunks;
944    file = store->file;
945
946    if (!file && !bitmap->mddev->bitmap_info.offset) {
947        /* No permanent bitmap - fill with '1s'. */
948        store->filemap = NULL;
949        store->file_pages = 0;
950        for (i = 0; i < chunks ; i++) {
951            /* if the disk bit is set, set the memory bit */
952            int needed = ((sector_t)(i+1) << (bitmap->counts.chunkshift)
953                      >= start);
954            bitmap_set_memory_bits(bitmap,
955                           (sector_t)i << bitmap->counts.chunkshift,
956                           needed);
957        }
958        return 0;
959    }
960
961    outofdate = test_bit(BITMAP_STALE, &bitmap->flags);
962    if (outofdate)
963        printk(KERN_INFO "%s: bitmap file is out of date, doing full "
964            "recovery\n", bmname(bitmap));
965
966    if (file && i_size_read(file->f_mapping->host) < store->bytes) {
967        printk(KERN_INFO "%s: bitmap file too short %lu < %lu\n",
968               bmname(bitmap),
969               (unsigned long) i_size_read(file->f_mapping->host),
970               store->bytes);
971        goto err;
972    }
973
974    oldindex = ~0L;
975    offset = 0;
976    if (!bitmap->mddev->bitmap_info.external)
977        offset = sizeof(bitmap_super_t);
978
979    for (i = 0; i < chunks; i++) {
980        int b;
981        index = file_page_index(&bitmap->storage, i);
982        bit = file_page_offset(&bitmap->storage, i);
983        if (index != oldindex) { /* this is a new page, read it in */
984            int count;
985            /* unmap the old page, we're done with it */
986            if (index == store->file_pages-1)
987                count = store->bytes - index * PAGE_SIZE;
988            else
989                count = PAGE_SIZE;
990            page = store->filemap[index];
991            if (file)
992                ret = read_page(file, index, bitmap,
993                        count, page);
994            else
995                ret = read_sb_page(
996                    bitmap->mddev,
997                    bitmap->mddev->bitmap_info.offset,
998                    page,
999                    index, count);
1000
1001            if (ret)
1002                goto err;
1003
1004            oldindex = index;
1005
1006            if (outofdate) {
1007                /*
1008                 * if bitmap is out of date, dirty the
1009                 * whole page and write it out
1010                 */
1011                paddr = kmap_atomic(page);
1012                memset(paddr + offset, 0xff,
1013                       PAGE_SIZE - offset);
1014                kunmap_atomic(paddr);
1015                write_page(bitmap, page, 1);
1016
1017                ret = -EIO;
1018                if (test_bit(BITMAP_WRITE_ERROR,
1019                         &bitmap->flags))
1020                    goto err;
1021            }
1022        }
1023        paddr = kmap_atomic(page);
1024        if (test_bit(BITMAP_HOSTENDIAN, &bitmap->flags))
1025            b = test_bit(bit, paddr);
1026        else
1027            b = test_bit_le(bit, paddr);
1028        kunmap_atomic(paddr);
1029        if (b) {
1030            /* if the disk bit is set, set the memory bit */
1031            int needed = ((sector_t)(i+1) << bitmap->counts.chunkshift
1032                      >= start);
1033            bitmap_set_memory_bits(bitmap,
1034                           (sector_t)i << bitmap->counts.chunkshift,
1035                           needed);
1036            bit_cnt++;
1037        }
1038        offset = 0;
1039    }
1040
1041    printk(KERN_INFO "%s: bitmap initialized from disk: "
1042           "read %lu pages, set %lu of %lu bits\n",
1043           bmname(bitmap), store->file_pages,
1044           bit_cnt, chunks);
1045
1046    return 0;
1047
1048 err:
1049    printk(KERN_INFO "%s: bitmap initialisation failed: %d\n",
1050           bmname(bitmap), ret);
1051    return ret;
1052}
1053
1054void bitmap_write_all(struct bitmap *bitmap)
1055{
1056    /* We don't actually write all bitmap blocks here,
1057     * just flag them as needing to be written
1058     */
1059    int i;
1060
1061    if (!bitmap || !bitmap->storage.filemap)
1062        return;
1063    if (bitmap->storage.file)
1064        /* Only one copy, so nothing needed */
1065        return;
1066
1067    for (i = 0; i < bitmap->storage.file_pages; i++)
1068        set_page_attr(bitmap, i,
1069                  BITMAP_PAGE_NEEDWRITE);
1070    bitmap->allclean = 0;
1071}
1072
1073static void bitmap_count_page(struct bitmap_counts *bitmap,
1074                  sector_t offset, int inc)
1075{
1076    sector_t chunk = offset >> bitmap->chunkshift;
1077    unsigned long page = chunk >> PAGE_COUNTER_SHIFT;
1078    bitmap->bp[page].count += inc;
1079    bitmap_checkfree(bitmap, page);
1080}
1081
1082static void bitmap_set_pending(struct bitmap_counts *bitmap, sector_t offset)
1083{
1084    sector_t chunk = offset >> bitmap->chunkshift;
1085    unsigned long page = chunk >> PAGE_COUNTER_SHIFT;
1086    struct bitmap_page *bp = &bitmap->bp[page];
1087
1088    if (!bp->pending)
1089        bp->pending = 1;
1090}
1091
1092static bitmap_counter_t *bitmap_get_counter(struct bitmap_counts *bitmap,
1093                        sector_t offset, sector_t *blocks,
1094                        int create);
1095
1096/*
1097 * bitmap daemon -- periodically wakes up to clean bits and flush pages
1098 * out to disk
1099 */
1100
1101void bitmap_daemon_work(struct mddev *mddev)
1102{
1103    struct bitmap *bitmap;
1104    unsigned long j;
1105    unsigned long nextpage;
1106    sector_t blocks;
1107    struct bitmap_counts *counts;
1108
1109    /* Use a mutex to guard daemon_work against
1110     * bitmap_destroy.
1111     */
1112    mutex_lock(&mddev->bitmap_info.mutex);
1113    bitmap = mddev->bitmap;
1114    if (bitmap == NULL) {
1115        mutex_unlock(&mddev->bitmap_info.mutex);
1116        return;
1117    }
1118    if (time_before(jiffies, bitmap->daemon_lastrun
1119            + mddev->bitmap_info.daemon_sleep))
1120        goto done;
1121
1122    bitmap->daemon_lastrun = jiffies;
1123    if (bitmap->allclean) {
1124        mddev->thread->timeout = MAX_SCHEDULE_TIMEOUT;
1125        goto done;
1126    }
1127    bitmap->allclean = 1;
1128
1129    /* Any file-page which is PENDING now needs to be written.
1130     * So set NEEDWRITE now, then after we make any last-minute changes
1131     * we will write it.
1132     */
1133    for (j = 0; j < bitmap->storage.file_pages; j++)
1134        if (test_and_clear_page_attr(bitmap, j,
1135                         BITMAP_PAGE_PENDING))
1136            set_page_attr(bitmap, j,
1137                      BITMAP_PAGE_NEEDWRITE);
1138
1139    if (bitmap->need_sync &&
1140        mddev->bitmap_info.external == 0) {
1141        /* Arrange for superblock update as well as
1142         * other changes */
1143        bitmap_super_t *sb;
1144        bitmap->need_sync = 0;
1145        if (bitmap->storage.filemap) {
1146            sb = kmap_atomic(bitmap->storage.sb_page);
1147            sb->events_cleared =
1148                cpu_to_le64(bitmap->events_cleared);
1149            kunmap_atomic(sb);
1150            set_page_attr(bitmap, 0,
1151                      BITMAP_PAGE_NEEDWRITE);
1152        }
1153    }
1154    /* Now look at the bitmap counters and if any are '2' or '1',
1155     * decrement and handle accordingly.
1156     */
1157    counts = &bitmap->counts;
1158    spin_lock_irq(&counts->lock);
1159    nextpage = 0;
1160    for (j = 0; j < counts->chunks; j++) {
1161        bitmap_counter_t *bmc;
1162        sector_t block = (sector_t)j << counts->chunkshift;
1163
1164        if (j == nextpage) {
1165            nextpage += PAGE_COUNTER_RATIO;
1166            if (!counts->bp[j >> PAGE_COUNTER_SHIFT].pending) {
1167                j |= PAGE_COUNTER_MASK;
1168                continue;
1169            }
1170            counts->bp[j >> PAGE_COUNTER_SHIFT].pending = 0;
1171        }
1172        bmc = bitmap_get_counter(counts,
1173                     block,
1174                     &blocks, 0);
1175
1176        if (!bmc) {
1177            j |= PAGE_COUNTER_MASK;
1178            continue;
1179        }
1180        if (*bmc == 1 && !bitmap->need_sync) {
1181            /* We can clear the bit */
1182            *bmc = 0;
1183            bitmap_count_page(counts, block, -1);
1184            bitmap_file_clear_bit(bitmap, block);
1185        } else if (*bmc && *bmc <= 2) {
1186            *bmc = 1;
1187            bitmap_set_pending(counts, block);
1188            bitmap->allclean = 0;
1189        }
1190    }
1191    spin_unlock_irq(&counts->lock);
1192
1193    /* Now start writeout on any page in NEEDWRITE that isn't DIRTY.
1194     * DIRTY pages need to be written by bitmap_unplug so it can wait
1195     * for them.
1196     * If we find any DIRTY page we stop there and let bitmap_unplug
1197     * handle all the rest. This is important in the case where
1198     * the first blocking holds the superblock and it has been updated.
1199     * We mustn't write any other blocks before the superblock.
1200     */
1201    for (j = 0;
1202         j < bitmap->storage.file_pages
1203             && !test_bit(BITMAP_STALE, &bitmap->flags);
1204         j++) {
1205
1206        if (test_page_attr(bitmap, j,
1207                   BITMAP_PAGE_DIRTY))
1208            /* bitmap_unplug will handle the rest */
1209            break;
1210        if (test_and_clear_page_attr(bitmap, j,
1211                         BITMAP_PAGE_NEEDWRITE)) {
1212            write_page(bitmap, bitmap->storage.filemap[j], 0);
1213        }
1214    }
1215
1216 done:
1217    if (bitmap->allclean == 0)
1218        mddev->thread->timeout =
1219            mddev->bitmap_info.daemon_sleep;
1220    mutex_unlock(&mddev->bitmap_info.mutex);
1221}
1222
1223static bitmap_counter_t *bitmap_get_counter(struct bitmap_counts *bitmap,
1224                        sector_t offset, sector_t *blocks,
1225                        int create)
1226__releases(bitmap->lock)
1227__acquires(bitmap->lock)
1228{
1229    /* If 'create', we might release the lock and reclaim it.
1230     * The lock must have been taken with interrupts enabled.
1231     * If !create, we don't release the lock.
1232     */
1233    sector_t chunk = offset >> bitmap->chunkshift;
1234    unsigned long page = chunk >> PAGE_COUNTER_SHIFT;
1235    unsigned long pageoff = (chunk & PAGE_COUNTER_MASK) << COUNTER_BYTE_SHIFT;
1236    sector_t csize;
1237    int err;
1238
1239    err = bitmap_checkpage(bitmap, page, create);
1240
1241    if (bitmap->bp[page].hijacked ||
1242        bitmap->bp[page].map == NULL)
1243        csize = ((sector_t)1) << (bitmap->chunkshift +
1244                      PAGE_COUNTER_SHIFT - 1);
1245    else
1246        csize = ((sector_t)1) << bitmap->chunkshift;
1247    *blocks = csize - (offset & (csize - 1));
1248
1249    if (err < 0)
1250        return NULL;
1251
1252    /* now locked ... */
1253
1254    if (bitmap->bp[page].hijacked) { /* hijacked pointer */
1255        /* should we use the first or second counter field
1256         * of the hijacked pointer? */
1257        int hi = (pageoff > PAGE_COUNTER_MASK);
1258        return &((bitmap_counter_t *)
1259              &bitmap->bp[page].map)[hi];
1260    } else /* page is allocated */
1261        return (bitmap_counter_t *)
1262            &(bitmap->bp[page].map[pageoff]);
1263}
1264
1265int bitmap_startwrite(struct bitmap *bitmap, sector_t offset, unsigned long sectors, int behind)
1266{
1267    if (!bitmap)
1268        return 0;
1269
1270    if (behind) {
1271        int bw;
1272        atomic_inc(&bitmap->behind_writes);
1273        bw = atomic_read(&bitmap->behind_writes);
1274        if (bw > bitmap->behind_writes_used)
1275            bitmap->behind_writes_used = bw;
1276
1277        pr_debug("inc write-behind count %d/%lu\n",
1278             bw, bitmap->mddev->bitmap_info.max_write_behind);
1279    }
1280
1281    while (sectors) {
1282        sector_t blocks;
1283        bitmap_counter_t *bmc;
1284
1285        spin_lock_irq(&bitmap->counts.lock);
1286        bmc = bitmap_get_counter(&bitmap->counts, offset, &blocks, 1);
1287        if (!bmc) {
1288            spin_unlock_irq(&bitmap->counts.lock);
1289            return 0;
1290        }
1291
1292        if (unlikely(COUNTER(*bmc) == COUNTER_MAX)) {
1293            DEFINE_WAIT(__wait);
1294            /* note that it is safe to do the prepare_to_wait
1295             * after the test as long as we do it before dropping
1296             * the spinlock.
1297             */
1298            prepare_to_wait(&bitmap->overflow_wait, &__wait,
1299                    TASK_UNINTERRUPTIBLE);
1300            spin_unlock_irq(&bitmap->counts.lock);
1301            schedule();
1302            finish_wait(&bitmap->overflow_wait, &__wait);
1303            continue;
1304        }
1305
1306        switch (*bmc) {
1307        case 0:
1308            bitmap_file_set_bit(bitmap, offset);
1309            bitmap_count_page(&bitmap->counts, offset, 1);
1310            /* fall through */
1311        case 1:
1312            *bmc = 2;
1313        }
1314
1315        (*bmc)++;
1316
1317        spin_unlock_irq(&bitmap->counts.lock);
1318
1319        offset += blocks;
1320        if (sectors > blocks)
1321            sectors -= blocks;
1322        else
1323            sectors = 0;
1324    }
1325    return 0;
1326}
1327EXPORT_SYMBOL(bitmap_startwrite);
1328
1329void bitmap_endwrite(struct bitmap *bitmap, sector_t offset, unsigned long sectors,
1330             int success, int behind)
1331{
1332    if (!bitmap)
1333        return;
1334    if (behind) {
1335        if (atomic_dec_and_test(&bitmap->behind_writes))
1336            wake_up(&bitmap->behind_wait);
1337        pr_debug("dec write-behind count %d/%lu\n",
1338             atomic_read(&bitmap->behind_writes),
1339             bitmap->mddev->bitmap_info.max_write_behind);
1340    }
1341
1342    while (sectors) {
1343        sector_t blocks;
1344        unsigned long flags;
1345        bitmap_counter_t *bmc;
1346
1347        spin_lock_irqsave(&bitmap->counts.lock, flags);
1348        bmc = bitmap_get_counter(&bitmap->counts, offset, &blocks, 0);
1349        if (!bmc) {
1350            spin_unlock_irqrestore(&bitmap->counts.lock, flags);
1351            return;
1352        }
1353
1354        if (success && !bitmap->mddev->degraded &&
1355            bitmap->events_cleared < bitmap->mddev->events) {
1356            bitmap->events_cleared = bitmap->mddev->events;
1357            bitmap->need_sync = 1;
1358            sysfs_notify_dirent_safe(bitmap->sysfs_can_clear);
1359        }
1360
1361        if (!success && !NEEDED(*bmc))
1362            *bmc |= NEEDED_MASK;
1363
1364        if (COUNTER(*bmc) == COUNTER_MAX)
1365            wake_up(&bitmap->overflow_wait);
1366
1367        (*bmc)--;
1368        if (*bmc <= 2) {
1369            bitmap_set_pending(&bitmap->counts, offset);
1370            bitmap->allclean = 0;
1371        }
1372        spin_unlock_irqrestore(&bitmap->counts.lock, flags);
1373        offset += blocks;
1374        if (sectors > blocks)
1375            sectors -= blocks;
1376        else
1377            sectors = 0;
1378    }
1379}
1380EXPORT_SYMBOL(bitmap_endwrite);
1381
1382static int __bitmap_start_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks,
1383                   int degraded)
1384{
1385    bitmap_counter_t *bmc;
1386    int rv;
1387    if (bitmap == NULL) {/* FIXME or bitmap set as 'failed' */
1388        *blocks = 1024;
1389        return 1; /* always resync if no bitmap */
1390    }
1391    spin_lock_irq(&bitmap->counts.lock);
1392    bmc = bitmap_get_counter(&bitmap->counts, offset, blocks, 0);
1393    rv = 0;
1394    if (bmc) {
1395        /* locked */
1396        if (RESYNC(*bmc))
1397            rv = 1;
1398        else if (NEEDED(*bmc)) {
1399            rv = 1;
1400            if (!degraded) { /* don't set/clear bits if degraded */
1401                *bmc |= RESYNC_MASK;
1402                *bmc &= ~NEEDED_MASK;
1403            }
1404        }
1405    }
1406    spin_unlock_irq(&bitmap->counts.lock);
1407    return rv;
1408}
1409
1410int bitmap_start_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks,
1411              int degraded)
1412{
1413    /* bitmap_start_sync must always report on multiples of whole
1414     * pages, otherwise resync (which is very PAGE_SIZE based) will
1415     * get confused.
1416     * So call __bitmap_start_sync repeatedly (if needed) until
1417     * At least PAGE_SIZE>>9 blocks are covered.
1418     * Return the 'or' of the result.
1419     */
1420    int rv = 0;
1421    sector_t blocks1;
1422
1423    *blocks = 0;
1424    while (*blocks < (PAGE_SIZE>>9)) {
1425        rv |= __bitmap_start_sync(bitmap, offset,
1426                      &blocks1, degraded);
1427        offset += blocks1;
1428        *blocks += blocks1;
1429    }
1430    return rv;
1431}
1432EXPORT_SYMBOL(bitmap_start_sync);
1433
1434void bitmap_end_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks, int aborted)
1435{
1436    bitmap_counter_t *bmc;
1437    unsigned long flags;
1438
1439    if (bitmap == NULL) {
1440        *blocks = 1024;
1441        return;
1442    }
1443    spin_lock_irqsave(&bitmap->counts.lock, flags);
1444    bmc = bitmap_get_counter(&bitmap->counts, offset, blocks, 0);
1445    if (bmc == NULL)
1446        goto unlock;
1447    /* locked */
1448    if (RESYNC(*bmc)) {
1449        *bmc &= ~RESYNC_MASK;
1450
1451        if (!NEEDED(*bmc) && aborted)
1452            *bmc |= NEEDED_MASK;
1453        else {
1454            if (*bmc <= 2) {
1455                bitmap_set_pending(&bitmap->counts, offset);
1456                bitmap->allclean = 0;
1457            }
1458        }
1459    }
1460 unlock:
1461    spin_unlock_irqrestore(&bitmap->counts.lock, flags);
1462}
1463EXPORT_SYMBOL(bitmap_end_sync);
1464
1465void bitmap_close_sync(struct bitmap *bitmap)
1466{
1467    /* Sync has finished, and any bitmap chunks that weren't synced
1468     * properly have been aborted. It remains to us to clear the
1469     * RESYNC bit wherever it is still on
1470     */
1471    sector_t sector = 0;
1472    sector_t blocks;
1473    if (!bitmap)
1474        return;
1475    while (sector < bitmap->mddev->resync_max_sectors) {
1476        bitmap_end_sync(bitmap, sector, &blocks, 0);
1477        sector += blocks;
1478    }
1479}
1480EXPORT_SYMBOL(bitmap_close_sync);
1481
1482void bitmap_cond_end_sync(struct bitmap *bitmap, sector_t sector)
1483{
1484    sector_t s = 0;
1485    sector_t blocks;
1486
1487    if (!bitmap)
1488        return;
1489    if (sector == 0) {
1490        bitmap->last_end_sync = jiffies;
1491        return;
1492    }
1493    if (time_before(jiffies, (bitmap->last_end_sync
1494                  + bitmap->mddev->bitmap_info.daemon_sleep)))
1495        return;
1496    wait_event(bitmap->mddev->recovery_wait,
1497           atomic_read(&bitmap->mddev->recovery_active) == 0);
1498
1499    bitmap->mddev->curr_resync_completed = sector;
1500    set_bit(MD_CHANGE_CLEAN, &bitmap->mddev->flags);
1501    sector &= ~((1ULL << bitmap->counts.chunkshift) - 1);
1502    s = 0;
1503    while (s < sector && s < bitmap->mddev->resync_max_sectors) {
1504        bitmap_end_sync(bitmap, s, &blocks, 0);
1505        s += blocks;
1506    }
1507    bitmap->last_end_sync = jiffies;
1508    sysfs_notify(&bitmap->mddev->kobj, NULL, "sync_completed");
1509}
1510EXPORT_SYMBOL(bitmap_cond_end_sync);
1511
1512static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset, int needed)
1513{
1514    /* For each chunk covered by any of these sectors, set the
1515     * counter to 2 and possibly set resync_needed. They should all
1516     * be 0 at this point
1517     */
1518
1519    sector_t secs;
1520    bitmap_counter_t *bmc;
1521    spin_lock_irq(&bitmap->counts.lock);
1522    bmc = bitmap_get_counter(&bitmap->counts, offset, &secs, 1);
1523    if (!bmc) {
1524        spin_unlock_irq(&bitmap->counts.lock);
1525        return;
1526    }
1527    if (!*bmc) {
1528        *bmc = 2 | (needed ? NEEDED_MASK : 0);
1529        bitmap_count_page(&bitmap->counts, offset, 1);
1530        bitmap_set_pending(&bitmap->counts, offset);
1531        bitmap->allclean = 0;
1532    }
1533    spin_unlock_irq(&bitmap->counts.lock);
1534}
1535
1536/* dirty the memory and file bits for bitmap chunks "s" to "e" */
1537void bitmap_dirty_bits(struct bitmap *bitmap, unsigned long s, unsigned long e)
1538{
1539    unsigned long chunk;
1540
1541    for (chunk = s; chunk <= e; chunk++) {
1542        sector_t sec = (sector_t)chunk << bitmap->counts.chunkshift;
1543        bitmap_set_memory_bits(bitmap, sec, 1);
1544        bitmap_file_set_bit(bitmap, sec);
1545        if (sec < bitmap->mddev->recovery_cp)
1546            /* We are asserting that the array is dirty,
1547             * so move the recovery_cp address back so
1548             * that it is obvious that it is dirty
1549             */
1550            bitmap->mddev->recovery_cp = sec;
1551    }
1552}
1553
1554/*
1555 * flush out any pending updates
1556 */
1557void bitmap_flush(struct mddev *mddev)
1558{
1559    struct bitmap *bitmap = mddev->bitmap;
1560    long sleep;
1561
1562    if (!bitmap) /* there was no bitmap */
1563        return;
1564
1565    /* run the daemon_work three time to ensure everything is flushed
1566     * that can be
1567     */
1568    sleep = mddev->bitmap_info.daemon_sleep * 2;
1569    bitmap->daemon_lastrun -= sleep;
1570    bitmap_daemon_work(mddev);
1571    bitmap->daemon_lastrun -= sleep;
1572    bitmap_daemon_work(mddev);
1573    bitmap->daemon_lastrun -= sleep;
1574    bitmap_daemon_work(mddev);
1575    bitmap_update_sb(bitmap);
1576}
1577
1578/*
1579 * free memory that was allocated
1580 */
1581static void bitmap_free(struct bitmap *bitmap)
1582{
1583    unsigned long k, pages;
1584    struct bitmap_page *bp;
1585
1586    if (!bitmap) /* there was no bitmap */
1587        return;
1588
1589    /* Shouldn't be needed - but just in case.... */
1590    wait_event(bitmap->write_wait,
1591           atomic_read(&bitmap->pending_writes) == 0);
1592
1593    /* release the bitmap file */
1594    bitmap_file_unmap(&bitmap->storage);
1595
1596    bp = bitmap->counts.bp;
1597    pages = bitmap->counts.pages;
1598
1599    /* free all allocated memory */
1600
1601    if (bp) /* deallocate the page memory */
1602        for (k = 0; k < pages; k++)
1603            if (bp[k].map && !bp[k].hijacked)
1604                kfree(bp[k].map);
1605    kfree(bp);
1606    kfree(bitmap);
1607}
1608
1609void bitmap_destroy(struct mddev *mddev)
1610{
1611    struct bitmap *bitmap = mddev->bitmap;
1612
1613    if (!bitmap) /* there was no bitmap */
1614        return;
1615
1616    mutex_lock(&mddev->bitmap_info.mutex);
1617    mddev->bitmap = NULL; /* disconnect from the md device */
1618    mutex_unlock(&mddev->bitmap_info.mutex);
1619    if (mddev->thread)
1620        mddev->thread->timeout = MAX_SCHEDULE_TIMEOUT;
1621
1622    if (bitmap->sysfs_can_clear)
1623        sysfs_put(bitmap->sysfs_can_clear);
1624
1625    bitmap_free(bitmap);
1626}
1627
1628/*
1629 * initialize the bitmap structure
1630 * if this returns an error, bitmap_destroy must be called to do clean up
1631 */
1632int bitmap_create(struct mddev *mddev)
1633{
1634    struct bitmap *bitmap;
1635    sector_t blocks = mddev->resync_max_sectors;
1636    struct file *file = mddev->bitmap_info.file;
1637    int err;
1638    struct sysfs_dirent *bm = NULL;
1639
1640    BUILD_BUG_ON(sizeof(bitmap_super_t) != 256);
1641
1642    BUG_ON(file && mddev->bitmap_info.offset);
1643
1644    bitmap = kzalloc(sizeof(*bitmap), GFP_KERNEL);
1645    if (!bitmap)
1646        return -ENOMEM;
1647
1648    spin_lock_init(&bitmap->counts.lock);
1649    atomic_set(&bitmap->pending_writes, 0);
1650    init_waitqueue_head(&bitmap->write_wait);
1651    init_waitqueue_head(&bitmap->overflow_wait);
1652    init_waitqueue_head(&bitmap->behind_wait);
1653
1654    bitmap->mddev = mddev;
1655
1656    if (mddev->kobj.sd)
1657        bm = sysfs_get_dirent(mddev->kobj.sd, NULL, "bitmap");
1658    if (bm) {
1659        bitmap->sysfs_can_clear = sysfs_get_dirent(bm, NULL, "can_clear");
1660        sysfs_put(bm);
1661    } else
1662        bitmap->sysfs_can_clear = NULL;
1663
1664    bitmap->storage.file = file;
1665    if (file) {
1666        get_file(file);
1667        /* As future accesses to this file will use bmap,
1668         * and bypass the page cache, we must sync the file
1669         * first.
1670         */
1671        vfs_fsync(file, 1);
1672    }
1673    /* read superblock from bitmap file (this sets mddev->bitmap_info.chunksize) */
1674    if (!mddev->bitmap_info.external) {
1675        /*
1676         * If 'MD_ARRAY_FIRST_USE' is set, then device-mapper is
1677         * instructing us to create a new on-disk bitmap instance.
1678         */
1679        if (test_and_clear_bit(MD_ARRAY_FIRST_USE, &mddev->flags))
1680            err = bitmap_new_disk_sb(bitmap);
1681        else
1682            err = bitmap_read_sb(bitmap);
1683    } else {
1684        err = 0;
1685        if (mddev->bitmap_info.chunksize == 0 ||
1686            mddev->bitmap_info.daemon_sleep == 0)
1687            /* chunksize and time_base need to be
1688             * set first. */
1689            err = -EINVAL;
1690    }
1691    if (err)
1692        goto error;
1693
1694    bitmap->daemon_lastrun = jiffies;
1695    err = bitmap_resize(bitmap, blocks, mddev->bitmap_info.chunksize, 1);
1696    if (err)
1697        goto error;
1698
1699    printk(KERN_INFO "created bitmap (%lu pages) for device %s\n",
1700           bitmap->counts.pages, bmname(bitmap));
1701
1702    mddev->bitmap = bitmap;
1703    return test_bit(BITMAP_WRITE_ERROR, &bitmap->flags) ? -EIO : 0;
1704
1705 error:
1706    bitmap_free(bitmap);
1707    return err;
1708}
1709
1710int bitmap_load(struct mddev *mddev)
1711{
1712    int err = 0;
1713    sector_t start = 0;
1714    sector_t sector = 0;
1715    struct bitmap *bitmap = mddev->bitmap;
1716
1717    if (!bitmap)
1718        goto out;
1719
1720    /* Clear out old bitmap info first: Either there is none, or we
1721     * are resuming after someone else has possibly changed things,
1722     * so we should forget old cached info.
1723     * All chunks should be clean, but some might need_sync.
1724     */
1725    while (sector < mddev->resync_max_sectors) {
1726        sector_t blocks;
1727        bitmap_start_sync(bitmap, sector, &blocks, 0);
1728        sector += blocks;
1729    }
1730    bitmap_close_sync(bitmap);
1731
1732    if (mddev->degraded == 0
1733        || bitmap->events_cleared == mddev->events)
1734        /* no need to keep dirty bits to optimise a
1735         * re-add of a missing device */
1736        start = mddev->recovery_cp;
1737
1738    mutex_lock(&mddev->bitmap_info.mutex);
1739    err = bitmap_init_from_disk(bitmap, start);
1740    mutex_unlock(&mddev->bitmap_info.mutex);
1741
1742    if (err)
1743        goto out;
1744    clear_bit(BITMAP_STALE, &bitmap->flags);
1745
1746    /* Kick recovery in case any bits were set */
1747    set_bit(MD_RECOVERY_NEEDED, &bitmap->mddev->recovery);
1748
1749    mddev->thread->timeout = mddev->bitmap_info.daemon_sleep;
1750    md_wakeup_thread(mddev->thread);
1751
1752    bitmap_update_sb(bitmap);
1753
1754    if (test_bit(BITMAP_WRITE_ERROR, &bitmap->flags))
1755        err = -EIO;
1756out:
1757    return err;
1758}
1759EXPORT_SYMBOL_GPL(bitmap_load);
1760
1761void bitmap_status(struct seq_file *seq, struct bitmap *bitmap)
1762{
1763    unsigned long chunk_kb;
1764    struct bitmap_counts *counts;
1765
1766    if (!bitmap)
1767        return;
1768
1769    counts = &bitmap->counts;
1770
1771    chunk_kb = bitmap->mddev->bitmap_info.chunksize >> 10;
1772    seq_printf(seq, "bitmap: %lu/%lu pages [%luKB], "
1773           "%lu%s chunk",
1774           counts->pages - counts->missing_pages,
1775           counts->pages,
1776           (counts->pages - counts->missing_pages)
1777           << (PAGE_SHIFT - 10),
1778           chunk_kb ? chunk_kb : bitmap->mddev->bitmap_info.chunksize,
1779           chunk_kb ? "KB" : "B");
1780    if (bitmap->storage.file) {
1781        seq_printf(seq, ", file: ");
1782        seq_path(seq, &bitmap->storage.file->f_path, " \t\n");
1783    }
1784
1785    seq_printf(seq, "\n");
1786}
1787
1788int bitmap_resize(struct bitmap *bitmap, sector_t blocks,
1789          int chunksize, int init)
1790{
1791    /* If chunk_size is 0, choose an appropriate chunk size.
1792     * Then possibly allocate new storage space.
1793     * Then quiesce, copy bits, replace bitmap, and re-start
1794     *
1795     * This function is called both to set up the initial bitmap
1796     * and to resize the bitmap while the array is active.
1797     * If this happens as a result of the array being resized,
1798     * chunksize will be zero, and we need to choose a suitable
1799     * chunksize, otherwise we use what we are given.
1800     */
1801    struct bitmap_storage store;
1802    struct bitmap_counts old_counts;
1803    unsigned long chunks;
1804    sector_t block;
1805    sector_t old_blocks, new_blocks;
1806    int chunkshift;
1807    int ret = 0;
1808    long pages;
1809    struct bitmap_page *new_bp;
1810
1811    if (chunksize == 0) {
1812        /* If there is enough space, leave the chunk size unchanged,
1813         * else increase by factor of two until there is enough space.
1814         */
1815        long bytes;
1816        long space = bitmap->mddev->bitmap_info.space;
1817
1818        if (space == 0) {
1819            /* We don't know how much space there is, so limit
1820             * to current size - in sectors.
1821             */
1822            bytes = DIV_ROUND_UP(bitmap->counts.chunks, 8);
1823            if (!bitmap->mddev->bitmap_info.external)
1824                bytes += sizeof(bitmap_super_t);
1825            space = DIV_ROUND_UP(bytes, 512);
1826            bitmap->mddev->bitmap_info.space = space;
1827        }
1828        chunkshift = bitmap->counts.chunkshift;
1829        chunkshift--;
1830        do {
1831            /* 'chunkshift' is shift from block size to chunk size */
1832            chunkshift++;
1833            chunks = DIV_ROUND_UP_SECTOR_T(blocks, 1 << chunkshift);
1834            bytes = DIV_ROUND_UP(chunks, 8);
1835            if (!bitmap->mddev->bitmap_info.external)
1836                bytes += sizeof(bitmap_super_t);
1837        } while (bytes > (space << 9));
1838    } else
1839        chunkshift = ffz(~chunksize) - BITMAP_BLOCK_SHIFT;
1840
1841    chunks = DIV_ROUND_UP_SECTOR_T(blocks, 1 << chunkshift);
1842    memset(&store, 0, sizeof(store));
1843    if (bitmap->mddev->bitmap_info.offset || bitmap->mddev->bitmap_info.file)
1844        ret = bitmap_storage_alloc(&store, chunks,
1845                       !bitmap->mddev->bitmap_info.external);
1846    if (ret)
1847        goto err;
1848
1849    pages = DIV_ROUND_UP(chunks, PAGE_COUNTER_RATIO);
1850
1851    new_bp = kzalloc(pages * sizeof(*new_bp), GFP_KERNEL);
1852    ret = -ENOMEM;
1853    if (!new_bp) {
1854        bitmap_file_unmap(&store);
1855        goto err;
1856    }
1857
1858    if (!init)
1859        bitmap->mddev->pers->quiesce(bitmap->mddev, 1);
1860
1861    store.file = bitmap->storage.file;
1862    bitmap->storage.file = NULL;
1863
1864    if (store.sb_page && bitmap->storage.sb_page)
1865        memcpy(page_address(store.sb_page),
1866               page_address(bitmap->storage.sb_page),
1867               sizeof(bitmap_super_t));
1868    bitmap_file_unmap(&bitmap->storage);
1869    bitmap->storage = store;
1870
1871    old_counts = bitmap->counts;
1872    bitmap->counts.bp = new_bp;
1873    bitmap->counts.pages = pages;
1874    bitmap->counts.missing_pages = pages;
1875    bitmap->counts.chunkshift = chunkshift;
1876    bitmap->counts.chunks = chunks;
1877    bitmap->mddev->bitmap_info.chunksize = 1 << (chunkshift +
1878                             BITMAP_BLOCK_SHIFT);
1879
1880    blocks = min(old_counts.chunks << old_counts.chunkshift,
1881             chunks << chunkshift);
1882
1883    spin_lock_irq(&bitmap->counts.lock);
1884    for (block = 0; block < blocks; ) {
1885        bitmap_counter_t *bmc_old, *bmc_new;
1886        int set;
1887
1888        bmc_old = bitmap_get_counter(&old_counts, block,
1889                         &old_blocks, 0);
1890        set = bmc_old && NEEDED(*bmc_old);
1891
1892        if (set) {
1893            bmc_new = bitmap_get_counter(&bitmap->counts, block,
1894                             &new_blocks, 1);
1895            if (*bmc_new == 0) {
1896                /* need to set on-disk bits too. */
1897                sector_t end = block + new_blocks;
1898                sector_t start = block >> chunkshift;
1899                start <<= chunkshift;
1900                while (start < end) {
1901                    bitmap_file_set_bit(bitmap, block);
1902                    start += 1 << chunkshift;
1903                }
1904                *bmc_new = 2;
1905                bitmap_count_page(&bitmap->counts,
1906                          block, 1);
1907                bitmap_set_pending(&bitmap->counts,
1908                           block);
1909            }
1910            *bmc_new |= NEEDED_MASK;
1911            if (new_blocks < old_blocks)
1912                old_blocks = new_blocks;
1913        }
1914        block += old_blocks;
1915    }
1916
1917    if (!init) {
1918        int i;
1919        while (block < (chunks << chunkshift)) {
1920            bitmap_counter_t *bmc;
1921            bmc = bitmap_get_counter(&bitmap->counts, block,
1922                         &new_blocks, 1);
1923            if (bmc) {
1924                /* new space. It needs to be resynced, so
1925                 * we set NEEDED_MASK.
1926                 */
1927                if (*bmc == 0) {
1928                    *bmc = NEEDED_MASK | 2;
1929                    bitmap_count_page(&bitmap->counts,
1930                              block, 1);
1931                    bitmap_set_pending(&bitmap->counts,
1932                               block);
1933                }
1934            }
1935            block += new_blocks;
1936        }
1937        for (i = 0; i < bitmap->storage.file_pages; i++)
1938            set_page_attr(bitmap, i, BITMAP_PAGE_DIRTY);
1939    }
1940    spin_unlock_irq(&bitmap->counts.lock);
1941
1942    if (!init) {
1943        bitmap_unplug(bitmap);
1944        bitmap->mddev->pers->quiesce(bitmap->mddev, 0);
1945    }
1946    ret = 0;
1947err:
1948    return ret;
1949}
1950EXPORT_SYMBOL_GPL(bitmap_resize);
1951
1952static ssize_t
1953location_show(struct mddev *mddev, char *page)
1954{
1955    ssize_t len;
1956    if (mddev->bitmap_info.file)
1957        len = sprintf(page, "file");
1958    else if (mddev->bitmap_info.offset)
1959        len = sprintf(page, "%+lld", (long long)mddev->bitmap_info.offset);
1960    else
1961        len = sprintf(page, "none");
1962    len += sprintf(page+len, "\n");
1963    return len;
1964}
1965
1966static ssize_t
1967location_store(struct mddev *mddev, const char *buf, size_t len)
1968{
1969
1970    if (mddev->pers) {
1971        if (!mddev->pers->quiesce)
1972            return -EBUSY;
1973        if (mddev->recovery || mddev->sync_thread)
1974            return -EBUSY;
1975    }
1976
1977    if (mddev->bitmap || mddev->bitmap_info.file ||
1978        mddev->bitmap_info.offset) {
1979        /* bitmap already configured. Only option is to clear it */
1980        if (strncmp(buf, "none", 4) != 0)
1981            return -EBUSY;
1982        if (mddev->pers) {
1983            mddev->pers->quiesce(mddev, 1);
1984            bitmap_destroy(mddev);
1985            mddev->pers->quiesce(mddev, 0);
1986        }
1987        mddev->bitmap_info.offset = 0;
1988        if (mddev->bitmap_info.file) {
1989            struct file *f = mddev->bitmap_info.file;
1990            mddev->bitmap_info.file = NULL;
1991            restore_bitmap_write_access(f);
1992            fput(f);
1993        }
1994    } else {
1995        /* No bitmap, OK to set a location */
1996        long long offset;
1997        if (strncmp(buf, "none", 4) == 0)
1998            /* nothing to be done */;
1999        else if (strncmp(buf, "file:", 5) == 0) {
2000            /* Not supported yet */
2001            return -EINVAL;
2002        } else {
2003            int rv;
2004            if (buf[0] == '+')
2005                rv = strict_strtoll(buf+1, 10, &offset);
2006            else
2007                rv = strict_strtoll(buf, 10, &offset);
2008            if (rv)
2009                return rv;
2010            if (offset == 0)
2011                return -EINVAL;
2012            if (mddev->bitmap_info.external == 0 &&
2013                mddev->major_version == 0 &&
2014                offset != mddev->bitmap_info.default_offset)
2015                return -EINVAL;
2016            mddev->bitmap_info.offset = offset;
2017            if (mddev->pers) {
2018                mddev->pers->quiesce(mddev, 1);
2019                rv = bitmap_create(mddev);
2020                if (!rv)
2021                    rv = bitmap_load(mddev);
2022                if (rv) {
2023                    bitmap_destroy(mddev);
2024                    mddev->bitmap_info.offset = 0;
2025                }
2026                mddev->pers->quiesce(mddev, 0);
2027                if (rv)
2028                    return rv;
2029            }
2030        }
2031    }
2032    if (!mddev->external) {
2033        /* Ensure new bitmap info is stored in
2034         * metadata promptly.
2035         */
2036        set_bit(MD_CHANGE_DEVS, &mddev->flags);
2037        md_wakeup_thread(mddev->thread);
2038    }
2039    return len;
2040}
2041
2042static struct md_sysfs_entry bitmap_location =
2043__ATTR(location, S_IRUGO|S_IWUSR, location_show, location_store);
2044
2045/* 'bitmap/space' is the space available at 'location' for the
2046 * bitmap. This allows the kernel to know when it is safe to
2047 * resize the bitmap to match a resized array.
2048 */
2049static ssize_t
2050space_show(struct mddev *mddev, char *page)
2051{
2052    return sprintf(page, "%lu\n", mddev->bitmap_info.space);
2053}
2054
2055static ssize_t
2056space_store(struct mddev *mddev, const char *buf, size_t len)
2057{
2058    unsigned long sectors;
2059    int rv;
2060
2061    rv = kstrtoul(buf, 10, &sectors);
2062    if (rv)
2063        return rv;
2064
2065    if (sectors == 0)
2066        return -EINVAL;
2067
2068    if (mddev->bitmap &&
2069        sectors < (mddev->bitmap->storage.bytes + 511) >> 9)
2070        return -EFBIG; /* Bitmap is too big for this small space */
2071
2072    /* could make sure it isn't too big, but that isn't really
2073     * needed - user-space should be careful.
2074     */
2075    mddev->bitmap_info.space = sectors;
2076    return len;
2077}
2078
2079static struct md_sysfs_entry bitmap_space =
2080__ATTR(space, S_IRUGO|S_IWUSR, space_show, space_store);
2081
2082static ssize_t
2083timeout_show(struct mddev *mddev, char *page)
2084{
2085    ssize_t len;
2086    unsigned long secs = mddev->bitmap_info.daemon_sleep / HZ;
2087    unsigned long jifs = mddev->bitmap_info.daemon_sleep % HZ;
2088
2089    len = sprintf(page, "%lu", secs);
2090    if (jifs)
2091        len += sprintf(page+len, ".%03u", jiffies_to_msecs(jifs));
2092    len += sprintf(page+len, "\n");
2093    return len;
2094}
2095
2096static ssize_t
2097timeout_store(struct mddev *mddev, const char *buf, size_t len)
2098{
2099    /* timeout can be set at any time */
2100    unsigned long timeout;
2101    int rv = strict_strtoul_scaled(buf, &timeout, 4);
2102    if (rv)
2103        return rv;
2104
2105    /* just to make sure we don't overflow... */
2106    if (timeout >= LONG_MAX / HZ)
2107        return -EINVAL;
2108
2109    timeout = timeout * HZ / 10000;
2110
2111    if (timeout >= MAX_SCHEDULE_TIMEOUT)
2112        timeout = MAX_SCHEDULE_TIMEOUT-1;
2113    if (timeout < 1)
2114        timeout = 1;
2115    mddev->bitmap_info.daemon_sleep = timeout;
2116    if (mddev->thread) {
2117        /* if thread->timeout is MAX_SCHEDULE_TIMEOUT, then
2118         * the bitmap is all clean and we don't need to
2119         * adjust the timeout right now
2120         */
2121        if (mddev->thread->timeout < MAX_SCHEDULE_TIMEOUT) {
2122            mddev->thread->timeout = timeout;
2123            md_wakeup_thread(mddev->thread);
2124        }
2125    }
2126    return len;
2127}
2128
2129static struct md_sysfs_entry bitmap_timeout =
2130__ATTR(time_base, S_IRUGO|S_IWUSR, timeout_show, timeout_store);
2131
2132static ssize_t
2133backlog_show(struct mddev *mddev, char *page)
2134{
2135    return sprintf(page, "%lu\n", mddev->bitmap_info.max_write_behind);
2136}
2137
2138static ssize_t
2139backlog_store(struct mddev *mddev, const char *buf, size_t len)
2140{
2141    unsigned long backlog;
2142    int rv = strict_strtoul(buf, 10, &backlog);
2143    if (rv)
2144        return rv;
2145    if (backlog > COUNTER_MAX)
2146        return -EINVAL;
2147    mddev->bitmap_info.max_write_behind = backlog;
2148    return len;
2149}
2150
2151static struct md_sysfs_entry bitmap_backlog =
2152__ATTR(backlog, S_IRUGO|S_IWUSR, backlog_show, backlog_store);
2153
2154static ssize_t
2155chunksize_show(struct mddev *mddev, char *page)
2156{
2157    return sprintf(page, "%lu\n", mddev->bitmap_info.chunksize);
2158}
2159
2160static ssize_t
2161chunksize_store(struct mddev *mddev, const char *buf, size_t len)
2162{
2163    /* Can only be changed when no bitmap is active */
2164    int rv;
2165    unsigned long csize;
2166    if (mddev->bitmap)
2167        return -EBUSY;
2168    rv = strict_strtoul(buf, 10, &csize);
2169    if (rv)
2170        return rv;
2171    if (csize < 512 ||
2172        !is_power_of_2(csize))
2173        return -EINVAL;
2174    mddev->bitmap_info.chunksize = csize;
2175    return len;
2176}
2177
2178static struct md_sysfs_entry bitmap_chunksize =
2179__ATTR(chunksize, S_IRUGO|S_IWUSR, chunksize_show, chunksize_store);
2180
2181static ssize_t metadata_show(struct mddev *mddev, char *page)
2182{
2183    return sprintf(page, "%s\n", (mddev->bitmap_info.external
2184                      ? "external" : "internal"));
2185}
2186
2187static ssize_t metadata_store(struct mddev *mddev, const char *buf, size_t len)
2188{
2189    if (mddev->bitmap ||
2190        mddev->bitmap_info.file ||
2191        mddev->bitmap_info.offset)
2192        return -EBUSY;
2193    if (strncmp(buf, "external", 8) == 0)
2194        mddev->bitmap_info.external = 1;
2195    else if (strncmp(buf, "internal", 8) == 0)
2196        mddev->bitmap_info.external = 0;
2197    else
2198        return -EINVAL;
2199    return len;
2200}
2201
2202static struct md_sysfs_entry bitmap_metadata =
2203__ATTR(metadata, S_IRUGO|S_IWUSR, metadata_show, metadata_store);
2204
2205static ssize_t can_clear_show(struct mddev *mddev, char *page)
2206{
2207    int len;
2208    if (mddev->bitmap)
2209        len = sprintf(page, "%s\n", (mddev->bitmap->need_sync ?
2210                         "false" : "true"));
2211    else
2212        len = sprintf(page, "\n");
2213    return len;
2214}
2215
2216static ssize_t can_clear_store(struct mddev *mddev, const char *buf, size_t len)
2217{
2218    if (mddev->bitmap == NULL)
2219        return -ENOENT;
2220    if (strncmp(buf, "false", 5) == 0)
2221        mddev->bitmap->need_sync = 1;
2222    else if (strncmp(buf, "true", 4) == 0) {
2223        if (mddev->degraded)
2224            return -EBUSY;
2225        mddev->bitmap->need_sync = 0;
2226    } else
2227        return -EINVAL;
2228    return len;
2229}
2230
2231static struct md_sysfs_entry bitmap_can_clear =
2232__ATTR(can_clear, S_IRUGO|S_IWUSR, can_clear_show, can_clear_store);
2233
2234static ssize_t
2235behind_writes_used_show(struct mddev *mddev, char *page)
2236{
2237    if (mddev->bitmap == NULL)
2238        return sprintf(page, "0\n");
2239    return sprintf(page, "%lu\n",
2240               mddev->bitmap->behind_writes_used);
2241}
2242
2243static ssize_t
2244behind_writes_used_reset(struct mddev *mddev, const char *buf, size_t len)
2245{
2246    if (mddev->bitmap)
2247        mddev->bitmap->behind_writes_used = 0;
2248    return len;
2249}
2250
2251static struct md_sysfs_entry max_backlog_used =
2252__ATTR(max_backlog_used, S_IRUGO | S_IWUSR,
2253       behind_writes_used_show, behind_writes_used_reset);
2254
2255static struct attribute *md_bitmap_attrs[] = {
2256    &bitmap_location.attr,
2257    &bitmap_space.attr,
2258    &bitmap_timeout.attr,
2259    &bitmap_backlog.attr,
2260    &bitmap_chunksize.attr,
2261    &bitmap_metadata.attr,
2262    &bitmap_can_clear.attr,
2263    &max_backlog_used.attr,
2264    NULL
2265};
2266struct attribute_group md_bitmap_group = {
2267    .name = "bitmap",
2268    .attrs = md_bitmap_attrs,
2269};
2270
2271

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