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_continue_rcu.
167     */
168    struct list_head *pos;
169    rcu_read_lock();
170    if (rdev == NULL)
171        /* start at the beginning */
172        pos = &mddev->disks;
173    else {
174        /* release the previous rdev and start from there. */
175        rdev_dec_pending(rdev, mddev);
176        pos = &rdev->same_set;
177    }
178    list_for_each_continue_rcu(pos, &mddev->disks) {
179        rdev = list_entry(pos, struct md_rdev, same_set);
180        if (rdev->raid_disk >= 0 &&
181            !test_bit(Faulty, &rdev->flags)) {
182            /* this is a usable devices */
183            atomic_inc(&rdev->nr_pending);
184            rcu_read_unlock();
185            return rdev;
186        }
187    }
188    rcu_read_unlock();
189    return NULL;
190}
191
192static int write_sb_page(struct bitmap *bitmap, struct page *page, int wait)
193{
194    struct md_rdev *rdev = NULL;
195    struct block_device *bdev;
196    struct mddev *mddev = bitmap->mddev;
197    struct bitmap_storage *store = &bitmap->storage;
198
199    while ((rdev = next_active_rdev(rdev, mddev)) != NULL) {
200        int size = PAGE_SIZE;
201        loff_t offset = mddev->bitmap_info.offset;
202
203        bdev = (rdev->meta_bdev) ? rdev->meta_bdev : rdev->bdev;
204
205        if (page->index == store->file_pages-1) {
206            int last_page_size = store->bytes & (PAGE_SIZE-1);
207            if (last_page_size == 0)
208                last_page_size = PAGE_SIZE;
209            size = roundup(last_page_size,
210                       bdev_logical_block_size(bdev));
211        }
212        /* Just make sure we aren't corrupting data or
213         * metadata
214         */
215        if (mddev->external) {
216            /* Bitmap could be anywhere. */
217            if (rdev->sb_start + offset + (page->index
218                               * (PAGE_SIZE/512))
219                > rdev->data_offset
220                &&
221                rdev->sb_start + offset
222                < (rdev->data_offset + mddev->dev_sectors
223                 + (PAGE_SIZE/512)))
224                goto bad_alignment;
225        } else if (offset < 0) {
226            /* DATA BITMAP METADATA */
227            if (offset
228                + (long)(page->index * (PAGE_SIZE/512))
229                + size/512 > 0)
230                /* bitmap runs in to metadata */
231                goto bad_alignment;
232            if (rdev->data_offset + mddev->dev_sectors
233                > rdev->sb_start + offset)
234                /* data runs in to bitmap */
235                goto bad_alignment;
236        } else if (rdev->sb_start < rdev->data_offset) {
237            /* METADATA BITMAP DATA */
238            if (rdev->sb_start
239                + offset
240                + page->index*(PAGE_SIZE/512) + size/512
241                > rdev->data_offset)
242                /* bitmap runs in to data */
243                goto bad_alignment;
244        } else {
245            /* DATA METADATA BITMAP - no problems */
246        }
247        md_super_write(mddev, rdev,
248                   rdev->sb_start + offset
249                   + page->index * (PAGE_SIZE/512),
250                   size,
251                   page);
252    }
253
254    if (wait)
255        md_super_wait(mddev);
256    return 0;
257
258 bad_alignment:
259    return -EINVAL;
260}
261
262static void bitmap_file_kick(struct bitmap *bitmap);
263/*
264 * write out a page to a file
265 */
266static void write_page(struct bitmap *bitmap, struct page *page, int wait)
267{
268    struct buffer_head *bh;
269
270    if (bitmap->storage.file == NULL) {
271        switch (write_sb_page(bitmap, page, wait)) {
272        case -EINVAL:
273            set_bit(BITMAP_WRITE_ERROR, &bitmap->flags);
274        }
275    } else {
276
277        bh = page_buffers(page);
278
279        while (bh && bh->b_blocknr) {
280            atomic_inc(&bitmap->pending_writes);
281            set_buffer_locked(bh);
282            set_buffer_mapped(bh);
283            submit_bh(WRITE | REQ_SYNC, bh);
284            bh = bh->b_this_page;
285        }
286
287        if (wait)
288            wait_event(bitmap->write_wait,
289                   atomic_read(&bitmap->pending_writes)==0);
290    }
291    if (test_bit(BITMAP_WRITE_ERROR, &bitmap->flags))
292        bitmap_file_kick(bitmap);
293}
294
295static void end_bitmap_write(struct buffer_head *bh, int uptodate)
296{
297    struct bitmap *bitmap = bh->b_private;
298
299    if (!uptodate)
300        set_bit(BITMAP_WRITE_ERROR, &bitmap->flags);
301    if (atomic_dec_and_test(&bitmap->pending_writes))
302        wake_up(&bitmap->write_wait);
303}
304
305/* copied from buffer.c */
306static void
307__clear_page_buffers(struct page *page)
308{
309    ClearPagePrivate(page);
310    set_page_private(page, 0);
311    page_cache_release(page);
312}
313static void free_buffers(struct page *page)
314{
315    struct buffer_head *bh;
316
317    if (!PagePrivate(page))
318        return;
319
320    bh = page_buffers(page);
321    while (bh) {
322        struct buffer_head *next = bh->b_this_page;
323        free_buffer_head(bh);
324        bh = next;
325    }
326    __clear_page_buffers(page);
327    put_page(page);
328}
329
330/* read a page from a file.
331 * We both read the page, and attach buffers to the page to record the
332 * address of each block (using bmap). These addresses will be used
333 * to write the block later, completely bypassing the filesystem.
334 * This usage is similar to how swap files are handled, and allows us
335 * to write to a file with no concerns of memory allocation failing.
336 */
337static int read_page(struct file *file, unsigned long index,
338             struct bitmap *bitmap,
339             unsigned long count,
340             struct page *page)
341{
342    int ret = 0;
343    struct inode *inode = file->f_path.dentry->d_inode;
344    struct buffer_head *bh;
345    sector_t block;
346
347    pr_debug("read bitmap file (%dB @ %llu)\n", (int)PAGE_SIZE,
348         (unsigned long long)index << PAGE_SHIFT);
349
350    bh = alloc_page_buffers(page, 1<<inode->i_blkbits, 0);
351    if (!bh) {
352        ret = -ENOMEM;
353        goto out;
354    }
355    attach_page_buffers(page, bh);
356    block = index << (PAGE_SHIFT - inode->i_blkbits);
357    while (bh) {
358        if (count == 0)
359            bh->b_blocknr = 0;
360        else {
361            bh->b_blocknr = bmap(inode, block);
362            if (bh->b_blocknr == 0) {
363                /* Cannot use this file! */
364                ret = -EINVAL;
365                goto out;
366            }
367            bh->b_bdev = inode->i_sb->s_bdev;
368            if (count < (1<<inode->i_blkbits))
369                count = 0;
370            else
371                count -= (1<<inode->i_blkbits);
372
373            bh->b_end_io = end_bitmap_write;
374            bh->b_private = bitmap;
375            atomic_inc(&bitmap->pending_writes);
376            set_buffer_locked(bh);
377            set_buffer_mapped(bh);
378            submit_bh(READ, bh);
379        }
380        block++;
381        bh = bh->b_this_page;
382    }
383    page->index = index;
384
385    wait_event(bitmap->write_wait,
386           atomic_read(&bitmap->pending_writes)==0);
387    if (test_bit(BITMAP_WRITE_ERROR, &bitmap->flags))
388        ret = -EIO;
389out:
390    if (ret)
391        printk(KERN_ALERT "md: bitmap read error: (%dB @ %llu): %d\n",
392            (int)PAGE_SIZE,
393            (unsigned long long)index << PAGE_SHIFT,
394            ret);
395    return ret;
396}
397
398/*
399 * bitmap file superblock operations
400 */
401
402/* update the event counter and sync the superblock to disk */
403void bitmap_update_sb(struct bitmap *bitmap)
404{
405    bitmap_super_t *sb;
406
407    if (!bitmap || !bitmap->mddev) /* no bitmap for this array */
408        return;
409    if (bitmap->mddev->bitmap_info.external)
410        return;
411    if (!bitmap->storage.sb_page) /* no superblock */
412        return;
413    sb = kmap_atomic(bitmap->storage.sb_page);
414    sb->events = cpu_to_le64(bitmap->mddev->events);
415    if (bitmap->mddev->events < bitmap->events_cleared)
416        /* rocking back to read-only */
417        bitmap->events_cleared = bitmap->mddev->events;
418    sb->events_cleared = cpu_to_le64(bitmap->events_cleared);
419    sb->state = cpu_to_le32(bitmap->flags);
420    /* Just in case these have been changed via sysfs: */
421    sb->daemon_sleep = cpu_to_le32(bitmap->mddev->bitmap_info.daemon_sleep/HZ);
422    sb->write_behind = cpu_to_le32(bitmap->mddev->bitmap_info.max_write_behind);
423    /* This might have been changed by a reshape */
424    sb->sync_size = cpu_to_le64(bitmap->mddev->resync_max_sectors);
425    sb->chunksize = cpu_to_le32(bitmap->mddev->bitmap_info.chunksize);
426    sb->sectors_reserved = cpu_to_le32(bitmap->mddev->
427                       bitmap_info.space);
428    kunmap_atomic(sb);
429    write_page(bitmap, bitmap->storage.sb_page, 1);
430}
431
432/* print out the bitmap file superblock */
433void bitmap_print_sb(struct bitmap *bitmap)
434{
435    bitmap_super_t *sb;
436
437    if (!bitmap || !bitmap->storage.sb_page)
438        return;
439    sb = kmap_atomic(bitmap->storage.sb_page);
440    printk(KERN_DEBUG "%s: bitmap file superblock:\n", bmname(bitmap));
441    printk(KERN_DEBUG " magic: %08x\n", le32_to_cpu(sb->magic));
442    printk(KERN_DEBUG " version: %d\n", le32_to_cpu(sb->version));
443    printk(KERN_DEBUG " uuid: %08x.%08x.%08x.%08x\n",
444                    *(__u32 *)(sb->uuid+0),
445                    *(__u32 *)(sb->uuid+4),
446                    *(__u32 *)(sb->uuid+8),
447                    *(__u32 *)(sb->uuid+12));
448    printk(KERN_DEBUG " events: %llu\n",
449            (unsigned long long) le64_to_cpu(sb->events));
450    printk(KERN_DEBUG "events cleared: %llu\n",
451            (unsigned long long) le64_to_cpu(sb->events_cleared));
452    printk(KERN_DEBUG " state: %08x\n", le32_to_cpu(sb->state));
453    printk(KERN_DEBUG " chunksize: %d B\n", le32_to_cpu(sb->chunksize));
454    printk(KERN_DEBUG " daemon sleep: %ds\n", le32_to_cpu(sb->daemon_sleep));
455    printk(KERN_DEBUG " sync size: %llu KB\n",
456            (unsigned long long)le64_to_cpu(sb->sync_size)/2);
457    printk(KERN_DEBUG "max write behind: %d\n", le32_to_cpu(sb->write_behind));
458    kunmap_atomic(sb);
459}
460
461/*
462 * bitmap_new_disk_sb
463 * @bitmap
464 *
465 * This function is somewhat the reverse of bitmap_read_sb. bitmap_read_sb
466 * reads and verifies the on-disk bitmap superblock and populates bitmap_info.
467 * This function verifies 'bitmap_info' and populates the on-disk bitmap
468 * structure, which is to be written to disk.
469 *
470 * Returns: 0 on success, -Exxx on error
471 */
472static int bitmap_new_disk_sb(struct bitmap *bitmap)
473{
474    bitmap_super_t *sb;
475    unsigned long chunksize, daemon_sleep, write_behind;
476    int err = -EINVAL;
477
478    bitmap->storage.sb_page = alloc_page(GFP_KERNEL);
479    if (IS_ERR(bitmap->storage.sb_page)) {
480        err = PTR_ERR(bitmap->storage.sb_page);
481        bitmap->storage.sb_page = NULL;
482        return err;
483    }
484    bitmap->storage.sb_page->index = 0;
485
486    sb = kmap_atomic(bitmap->storage.sb_page);
487
488    sb->magic = cpu_to_le32(BITMAP_MAGIC);
489    sb->version = cpu_to_le32(BITMAP_MAJOR_HI);
490
491    chunksize = bitmap->mddev->bitmap_info.chunksize;
492    BUG_ON(!chunksize);
493    if (!is_power_of_2(chunksize)) {
494        kunmap_atomic(sb);
495        printk(KERN_ERR "bitmap chunksize not a power of 2\n");
496        return -EINVAL;
497    }
498    sb->chunksize = cpu_to_le32(chunksize);
499
500    daemon_sleep = bitmap->mddev->bitmap_info.daemon_sleep;
501    if (!daemon_sleep ||
502        (daemon_sleep < 1) || (daemon_sleep > MAX_SCHEDULE_TIMEOUT)) {
503        printk(KERN_INFO "Choosing daemon_sleep default (5 sec)\n");
504        daemon_sleep = 5 * HZ;
505    }
506    sb->daemon_sleep = cpu_to_le32(daemon_sleep);
507    bitmap->mddev->bitmap_info.daemon_sleep = daemon_sleep;
508
509    /*
510     * FIXME: write_behind for RAID1. If not specified, what
511     * is a good choice? We choose COUNTER_MAX / 2 arbitrarily.
512     */
513    write_behind = bitmap->mddev->bitmap_info.max_write_behind;
514    if (write_behind > COUNTER_MAX)
515        write_behind = COUNTER_MAX / 2;
516    sb->write_behind = cpu_to_le32(write_behind);
517    bitmap->mddev->bitmap_info.max_write_behind = write_behind;
518
519    /* keep the array size field of the bitmap superblock up to date */
520    sb->sync_size = cpu_to_le64(bitmap->mddev->resync_max_sectors);
521
522    memcpy(sb->uuid, bitmap->mddev->uuid, 16);
523
524    set_bit(BITMAP_STALE, &bitmap->flags);
525    sb->state = cpu_to_le32(bitmap->flags);
526    bitmap->events_cleared = bitmap->mddev->events;
527    sb->events_cleared = cpu_to_le64(bitmap->mddev->events);
528
529    kunmap_atomic(sb);
530
531    return 0;
532}
533
534/* read the superblock from the bitmap file and initialize some bitmap fields */
535static int bitmap_read_sb(struct bitmap *bitmap)
536{
537    char *reason = NULL;
538    bitmap_super_t *sb;
539    unsigned long chunksize, daemon_sleep, write_behind;
540    unsigned long long events;
541    unsigned long sectors_reserved = 0;
542    int err = -EINVAL;
543    struct page *sb_page;
544
545    if (!bitmap->storage.file && !bitmap->mddev->bitmap_info.offset) {
546        chunksize = 128 * 1024 * 1024;
547        daemon_sleep = 5 * HZ;
548        write_behind = 0;
549        set_bit(BITMAP_STALE, &bitmap->flags);
550        err = 0;
551        goto out_no_sb;
552    }
553    /* page 0 is the superblock, read it... */
554    sb_page = alloc_page(GFP_KERNEL);
555    if (!sb_page)
556        return -ENOMEM;
557    bitmap->storage.sb_page = sb_page;
558
559    if (bitmap->storage.file) {
560        loff_t isize = i_size_read(bitmap->storage.file->f_mapping->host);
561        int bytes = isize > PAGE_SIZE ? PAGE_SIZE : isize;
562
563        err = read_page(bitmap->storage.file, 0,
564                bitmap, bytes, sb_page);
565    } else {
566        err = read_sb_page(bitmap->mddev,
567                   bitmap->mddev->bitmap_info.offset,
568                   sb_page,
569                   0, sizeof(bitmap_super_t));
570    }
571    if (err)
572        return err;
573
574    sb = kmap_atomic(sb_page);
575
576    chunksize = le32_to_cpu(sb->chunksize);
577    daemon_sleep = le32_to_cpu(sb->daemon_sleep) * HZ;
578    write_behind = le32_to_cpu(sb->write_behind);
579    sectors_reserved = le32_to_cpu(sb->sectors_reserved);
580
581    /* verify that the bitmap-specific fields are valid */
582    if (sb->magic != cpu_to_le32(BITMAP_MAGIC))
583        reason = "bad magic";
584    else if (le32_to_cpu(sb->version) < BITMAP_MAJOR_LO ||
585         le32_to_cpu(sb->version) > BITMAP_MAJOR_HI)
586        reason = "unrecognized superblock version";
587    else if (chunksize < 512)
588        reason = "bitmap chunksize too small";
589    else if (!is_power_of_2(chunksize))
590        reason = "bitmap chunksize not a power of 2";
591    else if (daemon_sleep < 1 || daemon_sleep > MAX_SCHEDULE_TIMEOUT)
592        reason = "daemon sleep period out of range";
593    else if (write_behind > COUNTER_MAX)
594        reason = "write-behind limit out of range (0 - 16383)";
595    if (reason) {
596        printk(KERN_INFO "%s: invalid bitmap file superblock: %s\n",
597            bmname(bitmap), reason);
598        goto out;
599    }
600
601    /* keep the array size field of the bitmap superblock up to date */
602    sb->sync_size = cpu_to_le64(bitmap->mddev->resync_max_sectors);
603
604    if (bitmap->mddev->persistent) {
605        /*
606         * We have a persistent array superblock, so compare the
607         * bitmap's UUID and event counter to the mddev's
608         */
609        if (memcmp(sb->uuid, bitmap->mddev->uuid, 16)) {
610            printk(KERN_INFO
611                   "%s: bitmap superblock UUID mismatch\n",
612                   bmname(bitmap));
613            goto out;
614        }
615        events = le64_to_cpu(sb->events);
616        if (events < bitmap->mddev->events) {
617            printk(KERN_INFO
618                   "%s: bitmap file is out of date (%llu < %llu) "
619                   "-- forcing full recovery\n",
620                   bmname(bitmap), events,
621                   (unsigned long long) bitmap->mddev->events);
622            set_bit(BITMAP_STALE, &bitmap->flags);
623        }
624    }
625
626    /* assign fields using values from superblock */
627    bitmap->flags |= le32_to_cpu(sb->state);
628    if (le32_to_cpu(sb->version) == BITMAP_MAJOR_HOSTENDIAN)
629        set_bit(BITMAP_HOSTENDIAN, &bitmap->flags);
630    bitmap->events_cleared = le64_to_cpu(sb->events_cleared);
631    err = 0;
632out:
633    kunmap_atomic(sb);
634out_no_sb:
635    if (test_bit(BITMAP_STALE, &bitmap->flags))
636        bitmap->events_cleared = bitmap->mddev->events;
637    bitmap->mddev->bitmap_info.chunksize = chunksize;
638    bitmap->mddev->bitmap_info.daemon_sleep = daemon_sleep;
639    bitmap->mddev->bitmap_info.max_write_behind = write_behind;
640    if (bitmap->mddev->bitmap_info.space == 0 ||
641        bitmap->mddev->bitmap_info.space > sectors_reserved)
642        bitmap->mddev->bitmap_info.space = sectors_reserved;
643    if (err)
644        bitmap_print_sb(bitmap);
645    return err;
646}
647
648/*
649 * general bitmap file operations
650 */
651
652/*
653 * on-disk bitmap:
654 *
655 * Use one bit per "chunk" (block set). We do the disk I/O on the bitmap
656 * file a page at a time. There's a superblock at the start of the file.
657 */
658/* calculate the index of the page that contains this bit */
659static inline unsigned long file_page_index(struct bitmap_storage *store,
660                        unsigned long chunk)
661{
662    if (store->sb_page)
663        chunk += sizeof(bitmap_super_t) << 3;
664    return chunk >> PAGE_BIT_SHIFT;
665}
666
667/* calculate the (bit) offset of this bit within a page */
668static inline unsigned long file_page_offset(struct bitmap_storage *store,
669                         unsigned long chunk)
670{
671    if (store->sb_page)
672        chunk += sizeof(bitmap_super_t) << 3;
673    return chunk & (PAGE_BITS - 1);
674}
675
676/*
677 * return a pointer to the page in the filemap that contains the given bit
678 *
679 * this lookup is complicated by the fact that the bitmap sb might be exactly
680 * 1 page (e.g., x86) or less than 1 page -- so the bitmap might start on page
681 * 0 or page 1
682 */
683static inline struct page *filemap_get_page(struct bitmap_storage *store,
684                        unsigned long chunk)
685{
686    if (file_page_index(store, chunk) >= store->file_pages)
687        return NULL;
688    return store->filemap[file_page_index(store, chunk)
689                  - file_page_index(store, 0)];
690}
691
692static int bitmap_storage_alloc(struct bitmap_storage *store,
693                unsigned long chunks, int with_super)
694{
695    int pnum;
696    unsigned long num_pages;
697    unsigned long bytes;
698
699    bytes = DIV_ROUND_UP(chunks, 8);
700    if (with_super)
701        bytes += sizeof(bitmap_super_t);
702
703    num_pages = DIV_ROUND_UP(bytes, PAGE_SIZE);
704
705    store->filemap = kmalloc(sizeof(struct page *)
706                 * num_pages, GFP_KERNEL);
707    if (!store->filemap)
708        return -ENOMEM;
709
710    if (with_super && !store->sb_page) {
711        store->sb_page = alloc_page(GFP_KERNEL|__GFP_ZERO);
712        if (store->sb_page == NULL)
713            return -ENOMEM;
714        store->sb_page->index = 0;
715    }
716    pnum = 0;
717    if (store->sb_page) {
718        store->filemap[0] = store->sb_page;
719        pnum = 1;
720    }
721    for ( ; pnum < num_pages; pnum++) {
722        store->filemap[pnum] = alloc_page(GFP_KERNEL|__GFP_ZERO);
723        if (!store->filemap[pnum]) {
724            store->file_pages = pnum;
725            return -ENOMEM;
726        }
727        store->filemap[pnum]->index = pnum;
728    }
729    store->file_pages = pnum;
730
731    /* We need 4 bits per page, rounded up to a multiple
732     * of sizeof(unsigned long) */
733    store->filemap_attr = kzalloc(
734        roundup(DIV_ROUND_UP(num_pages*4, 8), sizeof(unsigned long)),
735        GFP_KERNEL);
736    if (!store->filemap_attr)
737        return -ENOMEM;
738
739    store->bytes = bytes;
740
741    return 0;
742}
743
744static void bitmap_file_unmap(struct bitmap_storage *store)
745{
746    struct page **map, *sb_page;
747    int pages;
748    struct file *file;
749
750    file = store->file;
751    map = store->filemap;
752    pages = store->file_pages;
753    sb_page = store->sb_page;
754
755    while (pages--)
756        if (map[pages] != sb_page) /* 0 is sb_page, release it below */
757            free_buffers(map[pages]);
758    kfree(map);
759    kfree(store->filemap_attr);
760
761    if (sb_page)
762        free_buffers(sb_page);
763
764    if (file) {
765        struct inode *inode = file->f_path.dentry->d_inode;
766        invalidate_mapping_pages(inode->i_mapping, 0, -1);
767        fput(file);
768    }
769}
770
771/*
772 * bitmap_file_kick - if an error occurs while manipulating the bitmap file
773 * then it is no longer reliable, so we stop using it and we mark the file
774 * as failed in the superblock
775 */
776static void bitmap_file_kick(struct bitmap *bitmap)
777{
778    char *path, *ptr = NULL;
779
780    if (!test_and_set_bit(BITMAP_STALE, &bitmap->flags)) {
781        bitmap_update_sb(bitmap);
782
783        if (bitmap->storage.file) {
784            path = kmalloc(PAGE_SIZE, GFP_KERNEL);
785            if (path)
786                ptr = d_path(&bitmap->storage.file->f_path,
787                         path, PAGE_SIZE);
788
789            printk(KERN_ALERT
790                  "%s: kicking failed bitmap file %s from array!\n",
791                  bmname(bitmap), IS_ERR(ptr) ? "" : ptr);
792
793            kfree(path);
794        } else
795            printk(KERN_ALERT
796                   "%s: disabling internal bitmap due to errors\n",
797                   bmname(bitmap));
798    }
799}
800
801enum bitmap_page_attr {
802    BITMAP_PAGE_DIRTY = 0, /* there are set bits that need to be synced */
803    BITMAP_PAGE_PENDING = 1, /* there are bits that are being cleaned.
804                    * i.e. counter is 1 or 2. */
805    BITMAP_PAGE_NEEDWRITE = 2, /* there are cleared bits that need to be synced */
806};
807
808static inline void set_page_attr(struct bitmap *bitmap, int pnum,
809                 enum bitmap_page_attr attr)
810{
811    set_bit((pnum<<2) + attr, bitmap->storage.filemap_attr);
812}
813
814static inline void clear_page_attr(struct bitmap *bitmap, int pnum,
815                   enum bitmap_page_attr attr)
816{
817    clear_bit((pnum<<2) + attr, bitmap->storage.filemap_attr);
818}
819
820static inline int test_page_attr(struct bitmap *bitmap, int pnum,
821                 enum bitmap_page_attr attr)
822{
823    return test_bit((pnum<<2) + attr, bitmap->storage.filemap_attr);
824}
825
826static inline int test_and_clear_page_attr(struct bitmap *bitmap, int pnum,
827                       enum bitmap_page_attr attr)
828{
829    return test_and_clear_bit((pnum<<2) + attr,
830                  bitmap->storage.filemap_attr);
831}
832/*
833 * bitmap_file_set_bit -- called before performing a write to the md device
834 * to set (and eventually sync) a particular bit in the bitmap file
835 *
836 * we set the bit immediately, then we record the page number so that
837 * when an unplug occurs, we can flush the dirty pages out to disk
838 */
839static void bitmap_file_set_bit(struct bitmap *bitmap, sector_t block)
840{
841    unsigned long bit;
842    struct page *page;
843    void *kaddr;
844    unsigned long chunk = block >> bitmap->counts.chunkshift;
845
846    page = filemap_get_page(&bitmap->storage, chunk);
847    if (!page)
848        return;
849    bit = file_page_offset(&bitmap->storage, chunk);
850
851    /* set the bit */
852    kaddr = kmap_atomic(page);
853    if (test_bit(BITMAP_HOSTENDIAN, &bitmap->flags))
854        set_bit(bit, kaddr);
855    else
856        test_and_set_bit_le(bit, kaddr);
857    kunmap_atomic(kaddr);
858    pr_debug("set file bit %lu page %lu\n", bit, page->index);
859    /* record page number so it gets flushed to disk when unplug occurs */
860    set_page_attr(bitmap, page->index, BITMAP_PAGE_DIRTY);
861}
862
863static void bitmap_file_clear_bit(struct bitmap *bitmap, sector_t block)
864{
865    unsigned long bit;
866    struct page *page;
867    void *paddr;
868    unsigned long chunk = block >> bitmap->counts.chunkshift;
869
870    page = filemap_get_page(&bitmap->storage, chunk);
871    if (!page)
872        return;
873    bit = file_page_offset(&bitmap->storage, chunk);
874    paddr = kmap_atomic(page);
875    if (test_bit(BITMAP_HOSTENDIAN, &bitmap->flags))
876        clear_bit(bit, paddr);
877    else
878        test_and_clear_bit_le(bit, paddr);
879    kunmap_atomic(paddr);
880    if (!test_page_attr(bitmap, page->index, BITMAP_PAGE_NEEDWRITE)) {
881        set_page_attr(bitmap, page->index, BITMAP_PAGE_PENDING);
882        bitmap->allclean = 0;
883    }
884}
885
886/* this gets called when the md device is ready to unplug its underlying
887 * (slave) device queues -- before we let any writes go down, we need to
888 * sync the dirty pages of the bitmap file to disk */
889void bitmap_unplug(struct bitmap *bitmap)
890{
891    unsigned long i;
892    int dirty, need_write;
893    int wait = 0;
894
895    if (!bitmap || !bitmap->storage.filemap ||
896        test_bit(BITMAP_STALE, &bitmap->flags))
897        return;
898
899    /* look at each page to see if there are any set bits that need to be
900     * flushed out to disk */
901    for (i = 0; i < bitmap->storage.file_pages; i++) {
902        if (!bitmap->storage.filemap)
903            return;
904        dirty = test_and_clear_page_attr(bitmap, i, BITMAP_PAGE_DIRTY);
905        need_write = test_and_clear_page_attr(bitmap, i,
906                              BITMAP_PAGE_NEEDWRITE);
907        if (dirty || need_write) {
908            clear_page_attr(bitmap, i, BITMAP_PAGE_PENDING);
909            write_page(bitmap, bitmap->storage.filemap[i], 0);
910        }
911        if (dirty)
912            wait = 1;
913    }
914    if (wait) { /* if any writes were performed, we need to wait on them */
915        if (bitmap->storage.file)
916            wait_event(bitmap->write_wait,
917                   atomic_read(&bitmap->pending_writes)==0);
918        else
919            md_super_wait(bitmap->mddev);
920    }
921    if (test_bit(BITMAP_WRITE_ERROR, &bitmap->flags))
922        bitmap_file_kick(bitmap);
923}
924EXPORT_SYMBOL(bitmap_unplug);
925
926static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset, int needed);
927/* * bitmap_init_from_disk -- called at bitmap_create time to initialize
928 * the in-memory bitmap from the on-disk bitmap -- also, sets up the
929 * memory mapping of the bitmap file
930 * Special cases:
931 * if there's no bitmap file, or if the bitmap file had been
932 * previously kicked from the array, we mark all the bits as
933 * 1's in order to cause a full resync.
934 *
935 * We ignore all bits for sectors that end earlier than 'start'.
936 * This is used when reading an out-of-date bitmap...
937 */
938static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
939{
940    unsigned long i, chunks, index, oldindex, bit;
941    struct page *page = NULL;
942    unsigned long bit_cnt = 0;
943    struct file *file;
944    unsigned long offset;
945    int outofdate;
946    int ret = -ENOSPC;
947    void *paddr;
948    struct bitmap_storage *store = &bitmap->storage;
949
950    chunks = bitmap->counts.chunks;
951    file = store->file;
952
953    if (!file && !bitmap->mddev->bitmap_info.offset) {
954        /* No permanent bitmap - fill with '1s'. */
955        store->filemap = NULL;
956        store->file_pages = 0;
957        for (i = 0; i < chunks ; i++) {
958            /* if the disk bit is set, set the memory bit */
959            int needed = ((sector_t)(i+1) << (bitmap->counts.chunkshift)
960                      >= start);
961            bitmap_set_memory_bits(bitmap,
962                           (sector_t)i << bitmap->counts.chunkshift,
963                           needed);
964        }
965        return 0;
966    }
967
968    outofdate = test_bit(BITMAP_STALE, &bitmap->flags);
969    if (outofdate)
970        printk(KERN_INFO "%s: bitmap file is out of date, doing full "
971            "recovery\n", bmname(bitmap));
972
973    if (file && i_size_read(file->f_mapping->host) < store->bytes) {
974        printk(KERN_INFO "%s: bitmap file too short %lu < %lu\n",
975               bmname(bitmap),
976               (unsigned long) i_size_read(file->f_mapping->host),
977               store->bytes);
978        goto err;
979    }
980
981    oldindex = ~0L;
982    offset = 0;
983    if (!bitmap->mddev->bitmap_info.external)
984        offset = sizeof(bitmap_super_t);
985
986    for (i = 0; i < chunks; i++) {
987        int b;
988        index = file_page_index(&bitmap->storage, i);
989        bit = file_page_offset(&bitmap->storage, i);
990        if (index != oldindex) { /* this is a new page, read it in */
991            int count;
992            /* unmap the old page, we're done with it */
993            if (index == store->file_pages-1)
994                count = store->bytes - index * PAGE_SIZE;
995            else
996                count = PAGE_SIZE;
997            page = store->filemap[index];
998            if (file)
999                ret = read_page(file, index, bitmap,
1000                        count, page);
1001            else
1002                ret = read_sb_page(
1003                    bitmap->mddev,
1004                    bitmap->mddev->bitmap_info.offset,
1005                    page,
1006                    index, count);
1007
1008            if (ret)
1009                goto err;
1010
1011            oldindex = index;
1012
1013            if (outofdate) {
1014                /*
1015                 * if bitmap is out of date, dirty the
1016                 * whole page and write it out
1017                 */
1018                paddr = kmap_atomic(page);
1019                memset(paddr + offset, 0xff,
1020                       PAGE_SIZE - offset);
1021                kunmap_atomic(paddr);
1022                write_page(bitmap, page, 1);
1023
1024                ret = -EIO;
1025                if (test_bit(BITMAP_WRITE_ERROR,
1026                         &bitmap->flags))
1027                    goto err;
1028            }
1029        }
1030        paddr = kmap_atomic(page);
1031        if (test_bit(BITMAP_HOSTENDIAN, &bitmap->flags))
1032            b = test_bit(bit, paddr);
1033        else
1034            b = test_bit_le(bit, paddr);
1035        kunmap_atomic(paddr);
1036        if (b) {
1037            /* if the disk bit is set, set the memory bit */
1038            int needed = ((sector_t)(i+1) << bitmap->counts.chunkshift
1039                      >= start);
1040            bitmap_set_memory_bits(bitmap,
1041                           (sector_t)i << bitmap->counts.chunkshift,
1042                           needed);
1043            bit_cnt++;
1044        }
1045        offset = 0;
1046    }
1047
1048    printk(KERN_INFO "%s: bitmap initialized from disk: "
1049           "read %lu pages, set %lu of %lu bits\n",
1050           bmname(bitmap), store->file_pages,
1051           bit_cnt, chunks);
1052
1053    return 0;
1054
1055 err:
1056    printk(KERN_INFO "%s: bitmap initialisation failed: %d\n",
1057           bmname(bitmap), ret);
1058    return ret;
1059}
1060
1061void bitmap_write_all(struct bitmap *bitmap)
1062{
1063    /* We don't actually write all bitmap blocks here,
1064     * just flag them as needing to be written
1065     */
1066    int i;
1067
1068    if (!bitmap || !bitmap->storage.filemap)
1069        return;
1070    if (bitmap->storage.file)
1071        /* Only one copy, so nothing needed */
1072        return;
1073
1074    for (i = 0; i < bitmap->storage.file_pages; i++)
1075        set_page_attr(bitmap, i,
1076                  BITMAP_PAGE_NEEDWRITE);
1077    bitmap->allclean = 0;
1078}
1079
1080static void bitmap_count_page(struct bitmap_counts *bitmap,
1081                  sector_t offset, int inc)
1082{
1083    sector_t chunk = offset >> bitmap->chunkshift;
1084    unsigned long page = chunk >> PAGE_COUNTER_SHIFT;
1085    bitmap->bp[page].count += inc;
1086    bitmap_checkfree(bitmap, page);
1087}
1088
1089static void bitmap_set_pending(struct bitmap_counts *bitmap, sector_t offset)
1090{
1091    sector_t chunk = offset >> bitmap->chunkshift;
1092    unsigned long page = chunk >> PAGE_COUNTER_SHIFT;
1093    struct bitmap_page *bp = &bitmap->bp[page];
1094
1095    if (!bp->pending)
1096        bp->pending = 1;
1097}
1098
1099static bitmap_counter_t *bitmap_get_counter(struct bitmap_counts *bitmap,
1100                        sector_t offset, sector_t *blocks,
1101                        int create);
1102
1103/*
1104 * bitmap daemon -- periodically wakes up to clean bits and flush pages
1105 * out to disk
1106 */
1107
1108void bitmap_daemon_work(struct mddev *mddev)
1109{
1110    struct bitmap *bitmap;
1111    unsigned long j;
1112    unsigned long nextpage;
1113    sector_t blocks;
1114    struct bitmap_counts *counts;
1115
1116    /* Use a mutex to guard daemon_work against
1117     * bitmap_destroy.
1118     */
1119    mutex_lock(&mddev->bitmap_info.mutex);
1120    bitmap = mddev->bitmap;
1121    if (bitmap == NULL) {
1122        mutex_unlock(&mddev->bitmap_info.mutex);
1123        return;
1124    }
1125    if (time_before(jiffies, bitmap->daemon_lastrun
1126            + mddev->bitmap_info.daemon_sleep))
1127        goto done;
1128
1129    bitmap->daemon_lastrun = jiffies;
1130    if (bitmap->allclean) {
1131        mddev->thread->timeout = MAX_SCHEDULE_TIMEOUT;
1132        goto done;
1133    }
1134    bitmap->allclean = 1;
1135
1136    /* Any file-page which is PENDING now needs to be written.
1137     * So set NEEDWRITE now, then after we make any last-minute changes
1138     * we will write it.
1139     */
1140    for (j = 0; j < bitmap->storage.file_pages; j++)
1141        if (test_and_clear_page_attr(bitmap, j,
1142                         BITMAP_PAGE_PENDING))
1143            set_page_attr(bitmap, j,
1144                      BITMAP_PAGE_NEEDWRITE);
1145
1146    if (bitmap->need_sync &&
1147        mddev->bitmap_info.external == 0) {
1148        /* Arrange for superblock update as well as
1149         * other changes */
1150        bitmap_super_t *sb;
1151        bitmap->need_sync = 0;
1152        if (bitmap->storage.filemap) {
1153            sb = kmap_atomic(bitmap->storage.sb_page);
1154            sb->events_cleared =
1155                cpu_to_le64(bitmap->events_cleared);
1156            kunmap_atomic(sb);
1157            set_page_attr(bitmap, 0,
1158                      BITMAP_PAGE_NEEDWRITE);
1159        }
1160    }
1161    /* Now look at the bitmap counters and if any are '2' or '1',
1162     * decrement and handle accordingly.
1163     */
1164    counts = &bitmap->counts;
1165    spin_lock_irq(&counts->lock);
1166    nextpage = 0;
1167    for (j = 0; j < counts->chunks; j++) {
1168        bitmap_counter_t *bmc;
1169        sector_t block = (sector_t)j << counts->chunkshift;
1170
1171        if (j == nextpage) {
1172            nextpage += PAGE_COUNTER_RATIO;
1173            if (!counts->bp[j >> PAGE_COUNTER_SHIFT].pending) {
1174                j |= PAGE_COUNTER_MASK;
1175                continue;
1176            }
1177            counts->bp[j >> PAGE_COUNTER_SHIFT].pending = 0;
1178        }
1179        bmc = bitmap_get_counter(counts,
1180                     block,
1181                     &blocks, 0);
1182
1183        if (!bmc) {
1184            j |= PAGE_COUNTER_MASK;
1185            continue;
1186        }
1187        if (*bmc == 1 && !bitmap->need_sync) {
1188            /* We can clear the bit */
1189            *bmc = 0;
1190            bitmap_count_page(counts, block, -1);
1191            bitmap_file_clear_bit(bitmap, block);
1192        } else if (*bmc && *bmc <= 2) {
1193            *bmc = 1;
1194            bitmap_set_pending(counts, block);
1195            bitmap->allclean = 0;
1196        }
1197    }
1198    spin_unlock_irq(&counts->lock);
1199
1200    /* Now start writeout on any page in NEEDWRITE that isn't DIRTY.
1201     * DIRTY pages need to be written by bitmap_unplug so it can wait
1202     * for them.
1203     * If we find any DIRTY page we stop there and let bitmap_unplug
1204     * handle all the rest. This is important in the case where
1205     * the first blocking holds the superblock and it has been updated.
1206     * We mustn't write any other blocks before the superblock.
1207     */
1208    for (j = 0;
1209         j < bitmap->storage.file_pages
1210             && !test_bit(BITMAP_STALE, &bitmap->flags);
1211         j++) {
1212
1213        if (test_page_attr(bitmap, j,
1214                   BITMAP_PAGE_DIRTY))
1215            /* bitmap_unplug will handle the rest */
1216            break;
1217        if (test_and_clear_page_attr(bitmap, j,
1218                         BITMAP_PAGE_NEEDWRITE)) {
1219            write_page(bitmap, bitmap->storage.filemap[j], 0);
1220        }
1221    }
1222
1223 done:
1224    if (bitmap->allclean == 0)
1225        mddev->thread->timeout =
1226            mddev->bitmap_info.daemon_sleep;
1227    mutex_unlock(&mddev->bitmap_info.mutex);
1228}
1229
1230static bitmap_counter_t *bitmap_get_counter(struct bitmap_counts *bitmap,
1231                        sector_t offset, sector_t *blocks,
1232                        int create)
1233__releases(bitmap->lock)
1234__acquires(bitmap->lock)
1235{
1236    /* If 'create', we might release the lock and reclaim it.
1237     * The lock must have been taken with interrupts enabled.
1238     * If !create, we don't release the lock.
1239     */
1240    sector_t chunk = offset >> bitmap->chunkshift;
1241    unsigned long page = chunk >> PAGE_COUNTER_SHIFT;
1242    unsigned long pageoff = (chunk & PAGE_COUNTER_MASK) << COUNTER_BYTE_SHIFT;
1243    sector_t csize;
1244    int err;
1245
1246    err = bitmap_checkpage(bitmap, page, create);
1247
1248    if (bitmap->bp[page].hijacked ||
1249        bitmap->bp[page].map == NULL)
1250        csize = ((sector_t)1) << (bitmap->chunkshift +
1251                      PAGE_COUNTER_SHIFT - 1);
1252    else
1253        csize = ((sector_t)1) << bitmap->chunkshift;
1254    *blocks = csize - (offset & (csize - 1));
1255
1256    if (err < 0)
1257        return NULL;
1258
1259    /* now locked ... */
1260
1261    if (bitmap->bp[page].hijacked) { /* hijacked pointer */
1262        /* should we use the first or second counter field
1263         * of the hijacked pointer? */
1264        int hi = (pageoff > PAGE_COUNTER_MASK);
1265        return &((bitmap_counter_t *)
1266              &bitmap->bp[page].map)[hi];
1267    } else /* page is allocated */
1268        return (bitmap_counter_t *)
1269            &(bitmap->bp[page].map[pageoff]);
1270}
1271
1272int bitmap_startwrite(struct bitmap *bitmap, sector_t offset, unsigned long sectors, int behind)
1273{
1274    if (!bitmap)
1275        return 0;
1276
1277    if (behind) {
1278        int bw;
1279        atomic_inc(&bitmap->behind_writes);
1280        bw = atomic_read(&bitmap->behind_writes);
1281        if (bw > bitmap->behind_writes_used)
1282            bitmap->behind_writes_used = bw;
1283
1284        pr_debug("inc write-behind count %d/%lu\n",
1285             bw, bitmap->mddev->bitmap_info.max_write_behind);
1286    }
1287
1288    while (sectors) {
1289        sector_t blocks;
1290        bitmap_counter_t *bmc;
1291
1292        spin_lock_irq(&bitmap->counts.lock);
1293        bmc = bitmap_get_counter(&bitmap->counts, offset, &blocks, 1);
1294        if (!bmc) {
1295            spin_unlock_irq(&bitmap->counts.lock);
1296            return 0;
1297        }
1298
1299        if (unlikely(COUNTER(*bmc) == COUNTER_MAX)) {
1300            DEFINE_WAIT(__wait);
1301            /* note that it is safe to do the prepare_to_wait
1302             * after the test as long as we do it before dropping
1303             * the spinlock.
1304             */
1305            prepare_to_wait(&bitmap->overflow_wait, &__wait,
1306                    TASK_UNINTERRUPTIBLE);
1307            spin_unlock_irq(&bitmap->counts.lock);
1308            schedule();
1309            finish_wait(&bitmap->overflow_wait, &__wait);
1310            continue;
1311        }
1312
1313        switch (*bmc) {
1314        case 0:
1315            bitmap_file_set_bit(bitmap, offset);
1316            bitmap_count_page(&bitmap->counts, offset, 1);
1317            /* fall through */
1318        case 1:
1319            *bmc = 2;
1320        }
1321
1322        (*bmc)++;
1323
1324        spin_unlock_irq(&bitmap->counts.lock);
1325
1326        offset += blocks;
1327        if (sectors > blocks)
1328            sectors -= blocks;
1329        else
1330            sectors = 0;
1331    }
1332    return 0;
1333}
1334EXPORT_SYMBOL(bitmap_startwrite);
1335
1336void bitmap_endwrite(struct bitmap *bitmap, sector_t offset, unsigned long sectors,
1337             int success, int behind)
1338{
1339    if (!bitmap)
1340        return;
1341    if (behind) {
1342        if (atomic_dec_and_test(&bitmap->behind_writes))
1343            wake_up(&bitmap->behind_wait);
1344        pr_debug("dec write-behind count %d/%lu\n",
1345             atomic_read(&bitmap->behind_writes),
1346             bitmap->mddev->bitmap_info.max_write_behind);
1347    }
1348
1349    while (sectors) {
1350        sector_t blocks;
1351        unsigned long flags;
1352        bitmap_counter_t *bmc;
1353
1354        spin_lock_irqsave(&bitmap->counts.lock, flags);
1355        bmc = bitmap_get_counter(&bitmap->counts, offset, &blocks, 0);
1356        if (!bmc) {
1357            spin_unlock_irqrestore(&bitmap->counts.lock, flags);
1358            return;
1359        }
1360
1361        if (success && !bitmap->mddev->degraded &&
1362            bitmap->events_cleared < bitmap->mddev->events) {
1363            bitmap->events_cleared = bitmap->mddev->events;
1364            bitmap->need_sync = 1;
1365            sysfs_notify_dirent_safe(bitmap->sysfs_can_clear);
1366        }
1367
1368        if (!success && !NEEDED(*bmc))
1369            *bmc |= NEEDED_MASK;
1370
1371        if (COUNTER(*bmc) == COUNTER_MAX)
1372            wake_up(&bitmap->overflow_wait);
1373
1374        (*bmc)--;
1375        if (*bmc <= 2) {
1376            bitmap_set_pending(&bitmap->counts, offset);
1377            bitmap->allclean = 0;
1378        }
1379        spin_unlock_irqrestore(&bitmap->counts.lock, flags);
1380        offset += blocks;
1381        if (sectors > blocks)
1382            sectors -= blocks;
1383        else
1384            sectors = 0;
1385    }
1386}
1387EXPORT_SYMBOL(bitmap_endwrite);
1388
1389static int __bitmap_start_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks,
1390                   int degraded)
1391{
1392    bitmap_counter_t *bmc;
1393    int rv;
1394    if (bitmap == NULL) {/* FIXME or bitmap set as 'failed' */
1395        *blocks = 1024;
1396        return 1; /* always resync if no bitmap */
1397    }
1398    spin_lock_irq(&bitmap->counts.lock);
1399    bmc = bitmap_get_counter(&bitmap->counts, offset, blocks, 0);
1400    rv = 0;
1401    if (bmc) {
1402        /* locked */
1403        if (RESYNC(*bmc))
1404            rv = 1;
1405        else if (NEEDED(*bmc)) {
1406            rv = 1;
1407            if (!degraded) { /* don't set/clear bits if degraded */
1408                *bmc |= RESYNC_MASK;
1409                *bmc &= ~NEEDED_MASK;
1410            }
1411        }
1412    }
1413    spin_unlock_irq(&bitmap->counts.lock);
1414    return rv;
1415}
1416
1417int bitmap_start_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks,
1418              int degraded)
1419{
1420    /* bitmap_start_sync must always report on multiples of whole
1421     * pages, otherwise resync (which is very PAGE_SIZE based) will
1422     * get confused.
1423     * So call __bitmap_start_sync repeatedly (if needed) until
1424     * At least PAGE_SIZE>>9 blocks are covered.
1425     * Return the 'or' of the result.
1426     */
1427    int rv = 0;
1428    sector_t blocks1;
1429
1430    *blocks = 0;
1431    while (*blocks < (PAGE_SIZE>>9)) {
1432        rv |= __bitmap_start_sync(bitmap, offset,
1433                      &blocks1, degraded);
1434        offset += blocks1;
1435        *blocks += blocks1;
1436    }
1437    return rv;
1438}
1439EXPORT_SYMBOL(bitmap_start_sync);
1440
1441void bitmap_end_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks, int aborted)
1442{
1443    bitmap_counter_t *bmc;
1444    unsigned long flags;
1445
1446    if (bitmap == NULL) {
1447        *blocks = 1024;
1448        return;
1449    }
1450    spin_lock_irqsave(&bitmap->counts.lock, flags);
1451    bmc = bitmap_get_counter(&bitmap->counts, offset, blocks, 0);
1452    if (bmc == NULL)
1453        goto unlock;
1454    /* locked */
1455    if (RESYNC(*bmc)) {
1456        *bmc &= ~RESYNC_MASK;
1457
1458        if (!NEEDED(*bmc) && aborted)
1459            *bmc |= NEEDED_MASK;
1460        else {
1461            if (*bmc <= 2) {
1462                bitmap_set_pending(&bitmap->counts, offset);
1463                bitmap->allclean = 0;
1464            }
1465        }
1466    }
1467 unlock:
1468    spin_unlock_irqrestore(&bitmap->counts.lock, flags);
1469}
1470EXPORT_SYMBOL(bitmap_end_sync);
1471
1472void bitmap_close_sync(struct bitmap *bitmap)
1473{
1474    /* Sync has finished, and any bitmap chunks that weren't synced
1475     * properly have been aborted. It remains to us to clear the
1476     * RESYNC bit wherever it is still on
1477     */
1478    sector_t sector = 0;
1479    sector_t blocks;
1480    if (!bitmap)
1481        return;
1482    while (sector < bitmap->mddev->resync_max_sectors) {
1483        bitmap_end_sync(bitmap, sector, &blocks, 0);
1484        sector += blocks;
1485    }
1486}
1487EXPORT_SYMBOL(bitmap_close_sync);
1488
1489void bitmap_cond_end_sync(struct bitmap *bitmap, sector_t sector)
1490{
1491    sector_t s = 0;
1492    sector_t blocks;
1493
1494    if (!bitmap)
1495        return;
1496    if (sector == 0) {
1497        bitmap->last_end_sync = jiffies;
1498        return;
1499    }
1500    if (time_before(jiffies, (bitmap->last_end_sync
1501                  + bitmap->mddev->bitmap_info.daemon_sleep)))
1502        return;
1503    wait_event(bitmap->mddev->recovery_wait,
1504           atomic_read(&bitmap->mddev->recovery_active) == 0);
1505
1506    bitmap->mddev->curr_resync_completed = sector;
1507    set_bit(MD_CHANGE_CLEAN, &bitmap->mddev->flags);
1508    sector &= ~((1ULL << bitmap->counts.chunkshift) - 1);
1509    s = 0;
1510    while (s < sector && s < bitmap->mddev->resync_max_sectors) {
1511        bitmap_end_sync(bitmap, s, &blocks, 0);
1512        s += blocks;
1513    }
1514    bitmap->last_end_sync = jiffies;
1515    sysfs_notify(&bitmap->mddev->kobj, NULL, "sync_completed");
1516}
1517EXPORT_SYMBOL(bitmap_cond_end_sync);
1518
1519static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset, int needed)
1520{
1521    /* For each chunk covered by any of these sectors, set the
1522     * counter to 2 and possibly set resync_needed. They should all
1523     * be 0 at this point
1524     */
1525
1526    sector_t secs;
1527    bitmap_counter_t *bmc;
1528    spin_lock_irq(&bitmap->counts.lock);
1529    bmc = bitmap_get_counter(&bitmap->counts, offset, &secs, 1);
1530    if (!bmc) {
1531        spin_unlock_irq(&bitmap->counts.lock);
1532        return;
1533    }
1534    if (!*bmc) {
1535        *bmc = 2 | (needed ? NEEDED_MASK : 0);
1536        bitmap_count_page(&bitmap->counts, offset, 1);
1537        bitmap_set_pending(&bitmap->counts, offset);
1538        bitmap->allclean = 0;
1539    }
1540    spin_unlock_irq(&bitmap->counts.lock);
1541}
1542
1543/* dirty the memory and file bits for bitmap chunks "s" to "e" */
1544void bitmap_dirty_bits(struct bitmap *bitmap, unsigned long s, unsigned long e)
1545{
1546    unsigned long chunk;
1547
1548    for (chunk = s; chunk <= e; chunk++) {
1549        sector_t sec = (sector_t)chunk << bitmap->counts.chunkshift;
1550        bitmap_set_memory_bits(bitmap, sec, 1);
1551        bitmap_file_set_bit(bitmap, sec);
1552        if (sec < bitmap->mddev->recovery_cp)
1553            /* We are asserting that the array is dirty,
1554             * so move the recovery_cp address back so
1555             * that it is obvious that it is dirty
1556             */
1557            bitmap->mddev->recovery_cp = sec;
1558    }
1559}
1560
1561/*
1562 * flush out any pending updates
1563 */
1564void bitmap_flush(struct mddev *mddev)
1565{
1566    struct bitmap *bitmap = mddev->bitmap;
1567    long sleep;
1568
1569    if (!bitmap) /* there was no bitmap */
1570        return;
1571
1572    /* run the daemon_work three time to ensure everything is flushed
1573     * that can be
1574     */
1575    sleep = mddev->bitmap_info.daemon_sleep * 2;
1576    bitmap->daemon_lastrun -= sleep;
1577    bitmap_daemon_work(mddev);
1578    bitmap->daemon_lastrun -= sleep;
1579    bitmap_daemon_work(mddev);
1580    bitmap->daemon_lastrun -= sleep;
1581    bitmap_daemon_work(mddev);
1582    bitmap_update_sb(bitmap);
1583}
1584
1585/*
1586 * free memory that was allocated
1587 */
1588static void bitmap_free(struct bitmap *bitmap)
1589{
1590    unsigned long k, pages;
1591    struct bitmap_page *bp;
1592
1593    if (!bitmap) /* there was no bitmap */
1594        return;
1595
1596    /* Shouldn't be needed - but just in case.... */
1597    wait_event(bitmap->write_wait,
1598           atomic_read(&bitmap->pending_writes) == 0);
1599
1600    /* release the bitmap file */
1601    bitmap_file_unmap(&bitmap->storage);
1602
1603    bp = bitmap->counts.bp;
1604    pages = bitmap->counts.pages;
1605
1606    /* free all allocated memory */
1607
1608    if (bp) /* deallocate the page memory */
1609        for (k = 0; k < pages; k++)
1610            if (bp[k].map && !bp[k].hijacked)
1611                kfree(bp[k].map);
1612    kfree(bp);
1613    kfree(bitmap);
1614}
1615
1616void bitmap_destroy(struct mddev *mddev)
1617{
1618    struct bitmap *bitmap = mddev->bitmap;
1619
1620    if (!bitmap) /* there was no bitmap */
1621        return;
1622
1623    mutex_lock(&mddev->bitmap_info.mutex);
1624    mddev->bitmap = NULL; /* disconnect from the md device */
1625    mutex_unlock(&mddev->bitmap_info.mutex);
1626    if (mddev->thread)
1627        mddev->thread->timeout = MAX_SCHEDULE_TIMEOUT;
1628
1629    if (bitmap->sysfs_can_clear)
1630        sysfs_put(bitmap->sysfs_can_clear);
1631
1632    bitmap_free(bitmap);
1633}
1634
1635/*
1636 * initialize the bitmap structure
1637 * if this returns an error, bitmap_destroy must be called to do clean up
1638 */
1639int bitmap_create(struct mddev *mddev)
1640{
1641    struct bitmap *bitmap;
1642    sector_t blocks = mddev->resync_max_sectors;
1643    struct file *file = mddev->bitmap_info.file;
1644    int err;
1645    struct sysfs_dirent *bm = NULL;
1646
1647    BUILD_BUG_ON(sizeof(bitmap_super_t) != 256);
1648
1649    BUG_ON(file && mddev->bitmap_info.offset);
1650
1651    bitmap = kzalloc(sizeof(*bitmap), GFP_KERNEL);
1652    if (!bitmap)
1653        return -ENOMEM;
1654
1655    spin_lock_init(&bitmap->counts.lock);
1656    atomic_set(&bitmap->pending_writes, 0);
1657    init_waitqueue_head(&bitmap->write_wait);
1658    init_waitqueue_head(&bitmap->overflow_wait);
1659    init_waitqueue_head(&bitmap->behind_wait);
1660
1661    bitmap->mddev = mddev;
1662
1663    if (mddev->kobj.sd)
1664        bm = sysfs_get_dirent(mddev->kobj.sd, NULL, "bitmap");
1665    if (bm) {
1666        bitmap->sysfs_can_clear = sysfs_get_dirent(bm, NULL, "can_clear");
1667        sysfs_put(bm);
1668    } else
1669        bitmap->sysfs_can_clear = NULL;
1670
1671    bitmap->storage.file = file;
1672    if (file) {
1673        get_file(file);
1674        /* As future accesses to this file will use bmap,
1675         * and bypass the page cache, we must sync the file
1676         * first.
1677         */
1678        vfs_fsync(file, 1);
1679    }
1680    /* read superblock from bitmap file (this sets mddev->bitmap_info.chunksize) */
1681    if (!mddev->bitmap_info.external) {
1682        /*
1683         * If 'MD_ARRAY_FIRST_USE' is set, then device-mapper is
1684         * instructing us to create a new on-disk bitmap instance.
1685         */
1686        if (test_and_clear_bit(MD_ARRAY_FIRST_USE, &mddev->flags))
1687            err = bitmap_new_disk_sb(bitmap);
1688        else
1689            err = bitmap_read_sb(bitmap);
1690    } else {
1691        err = 0;
1692        if (mddev->bitmap_info.chunksize == 0 ||
1693            mddev->bitmap_info.daemon_sleep == 0)
1694            /* chunksize and time_base need to be
1695             * set first. */
1696            err = -EINVAL;
1697    }
1698    if (err)
1699        goto error;
1700
1701    bitmap->daemon_lastrun = jiffies;
1702    err = bitmap_resize(bitmap, blocks, mddev->bitmap_info.chunksize, 1);
1703    if (err)
1704        goto error;
1705
1706    printk(KERN_INFO "created bitmap (%lu pages) for device %s\n",
1707           bitmap->counts.pages, bmname(bitmap));
1708
1709    mddev->bitmap = bitmap;
1710    return test_bit(BITMAP_WRITE_ERROR, &bitmap->flags) ? -EIO : 0;
1711
1712 error:
1713    bitmap_free(bitmap);
1714    return err;
1715}
1716
1717int bitmap_load(struct mddev *mddev)
1718{
1719    int err = 0;
1720    sector_t start = 0;
1721    sector_t sector = 0;
1722    struct bitmap *bitmap = mddev->bitmap;
1723
1724    if (!bitmap)
1725        goto out;
1726
1727    /* Clear out old bitmap info first: Either there is none, or we
1728     * are resuming after someone else has possibly changed things,
1729     * so we should forget old cached info.
1730     * All chunks should be clean, but some might need_sync.
1731     */
1732    while (sector < mddev->resync_max_sectors) {
1733        sector_t blocks;
1734        bitmap_start_sync(bitmap, sector, &blocks, 0);
1735        sector += blocks;
1736    }
1737    bitmap_close_sync(bitmap);
1738
1739    if (mddev->degraded == 0
1740        || bitmap->events_cleared == mddev->events)
1741        /* no need to keep dirty bits to optimise a
1742         * re-add of a missing device */
1743        start = mddev->recovery_cp;
1744
1745    mutex_lock(&mddev->bitmap_info.mutex);
1746    err = bitmap_init_from_disk(bitmap, start);
1747    mutex_unlock(&mddev->bitmap_info.mutex);
1748
1749    if (err)
1750        goto out;
1751    clear_bit(BITMAP_STALE, &bitmap->flags);
1752
1753    /* Kick recovery in case any bits were set */
1754    set_bit(MD_RECOVERY_NEEDED, &bitmap->mddev->recovery);
1755
1756    mddev->thread->timeout = mddev->bitmap_info.daemon_sleep;
1757    md_wakeup_thread(mddev->thread);
1758
1759    bitmap_update_sb(bitmap);
1760
1761    if (test_bit(BITMAP_WRITE_ERROR, &bitmap->flags))
1762        err = -EIO;
1763out:
1764    return err;
1765}
1766EXPORT_SYMBOL_GPL(bitmap_load);
1767
1768void bitmap_status(struct seq_file *seq, struct bitmap *bitmap)
1769{
1770    unsigned long chunk_kb;
1771    struct bitmap_counts *counts;
1772
1773    if (!bitmap)
1774        return;
1775
1776    counts = &bitmap->counts;
1777
1778    chunk_kb = bitmap->mddev->bitmap_info.chunksize >> 10;
1779    seq_printf(seq, "bitmap: %lu/%lu pages [%luKB], "
1780           "%lu%s chunk",
1781           counts->pages - counts->missing_pages,
1782           counts->pages,
1783           (counts->pages - counts->missing_pages)
1784           << (PAGE_SHIFT - 10),
1785           chunk_kb ? chunk_kb : bitmap->mddev->bitmap_info.chunksize,
1786           chunk_kb ? "KB" : "B");
1787    if (bitmap->storage.file) {
1788        seq_printf(seq, ", file: ");
1789        seq_path(seq, &bitmap->storage.file->f_path, " \t\n");
1790    }
1791
1792    seq_printf(seq, "\n");
1793}
1794
1795int bitmap_resize(struct bitmap *bitmap, sector_t blocks,
1796          int chunksize, int init)
1797{
1798    /* If chunk_size is 0, choose an appropriate chunk size.
1799     * Then possibly allocate new storage space.
1800     * Then quiesce, copy bits, replace bitmap, and re-start
1801     *
1802     * This function is called both to set up the initial bitmap
1803     * and to resize the bitmap while the array is active.
1804     * If this happens as a result of the array being resized,
1805     * chunksize will be zero, and we need to choose a suitable
1806     * chunksize, otherwise we use what we are given.
1807     */
1808    struct bitmap_storage store;
1809    struct bitmap_counts old_counts;
1810    unsigned long chunks;
1811    sector_t block;
1812    sector_t old_blocks, new_blocks;
1813    int chunkshift;
1814    int ret = 0;
1815    long pages;
1816    struct bitmap_page *new_bp;
1817
1818    if (chunksize == 0) {
1819        /* If there is enough space, leave the chunk size unchanged,
1820         * else increase by factor of two until there is enough space.
1821         */
1822        long bytes;
1823        long space = bitmap->mddev->bitmap_info.space;
1824
1825        if (space == 0) {
1826            /* We don't know how much space there is, so limit
1827             * to current size - in sectors.
1828             */
1829            bytes = DIV_ROUND_UP(bitmap->counts.chunks, 8);
1830            if (!bitmap->mddev->bitmap_info.external)
1831                bytes += sizeof(bitmap_super_t);
1832            space = DIV_ROUND_UP(bytes, 512);
1833            bitmap->mddev->bitmap_info.space = space;
1834        }
1835        chunkshift = bitmap->counts.chunkshift;
1836        chunkshift--;
1837        do {
1838            /* 'chunkshift' is shift from block size to chunk size */
1839            chunkshift++;
1840            chunks = DIV_ROUND_UP_SECTOR_T(blocks, 1 << chunkshift);
1841            bytes = DIV_ROUND_UP(chunks, 8);
1842            if (!bitmap->mddev->bitmap_info.external)
1843                bytes += sizeof(bitmap_super_t);
1844        } while (bytes > (space << 9));
1845    } else
1846        chunkshift = ffz(~chunksize) - BITMAP_BLOCK_SHIFT;
1847
1848    chunks = DIV_ROUND_UP_SECTOR_T(blocks, 1 << chunkshift);
1849    memset(&store, 0, sizeof(store));
1850    if (bitmap->mddev->bitmap_info.offset || bitmap->mddev->bitmap_info.file)
1851        ret = bitmap_storage_alloc(&store, chunks,
1852                       !bitmap->mddev->bitmap_info.external);
1853    if (ret)
1854        goto err;
1855
1856    pages = DIV_ROUND_UP(chunks, PAGE_COUNTER_RATIO);
1857
1858    new_bp = kzalloc(pages * sizeof(*new_bp), GFP_KERNEL);
1859    ret = -ENOMEM;
1860    if (!new_bp) {
1861        bitmap_file_unmap(&store);
1862        goto err;
1863    }
1864
1865    if (!init)
1866        bitmap->mddev->pers->quiesce(bitmap->mddev, 1);
1867
1868    store.file = bitmap->storage.file;
1869    bitmap->storage.file = NULL;
1870
1871    if (store.sb_page && bitmap->storage.sb_page)
1872        memcpy(page_address(store.sb_page),
1873               page_address(bitmap->storage.sb_page),
1874               sizeof(bitmap_super_t));
1875    bitmap_file_unmap(&bitmap->storage);
1876    bitmap->storage = store;
1877
1878    old_counts = bitmap->counts;
1879    bitmap->counts.bp = new_bp;
1880    bitmap->counts.pages = pages;
1881    bitmap->counts.missing_pages = pages;
1882    bitmap->counts.chunkshift = chunkshift;
1883    bitmap->counts.chunks = chunks;
1884    bitmap->mddev->bitmap_info.chunksize = 1 << (chunkshift +
1885                             BITMAP_BLOCK_SHIFT);
1886
1887    blocks = min(old_counts.chunks << old_counts.chunkshift,
1888             chunks << chunkshift);
1889
1890    spin_lock_irq(&bitmap->counts.lock);
1891    for (block = 0; block < blocks; ) {
1892        bitmap_counter_t *bmc_old, *bmc_new;
1893        int set;
1894
1895        bmc_old = bitmap_get_counter(&old_counts, block,
1896                         &old_blocks, 0);
1897        set = bmc_old && NEEDED(*bmc_old);
1898
1899        if (set) {
1900            bmc_new = bitmap_get_counter(&bitmap->counts, block,
1901                             &new_blocks, 1);
1902            if (*bmc_new == 0) {
1903                /* need to set on-disk bits too. */
1904                sector_t end = block + new_blocks;
1905                sector_t start = block >> chunkshift;
1906                start <<= chunkshift;
1907                while (start < end) {
1908                    bitmap_file_set_bit(bitmap, block);
1909                    start += 1 << chunkshift;
1910                }
1911                *bmc_new = 2;
1912                bitmap_count_page(&bitmap->counts,
1913                          block, 1);
1914                bitmap_set_pending(&bitmap->counts,
1915                           block);
1916            }
1917            *bmc_new |= NEEDED_MASK;
1918            if (new_blocks < old_blocks)
1919                old_blocks = new_blocks;
1920        }
1921        block += old_blocks;
1922    }
1923
1924    if (!init) {
1925        int i;
1926        while (block < (chunks << chunkshift)) {
1927            bitmap_counter_t *bmc;
1928            bmc = bitmap_get_counter(&bitmap->counts, block,
1929                         &new_blocks, 1);
1930            if (bmc) {
1931                /* new space. It needs to be resynced, so
1932                 * we set NEEDED_MASK.
1933                 */
1934                if (*bmc == 0) {
1935                    *bmc = NEEDED_MASK | 2;
1936                    bitmap_count_page(&bitmap->counts,
1937                              block, 1);
1938                    bitmap_set_pending(&bitmap->counts,
1939                               block);
1940                }
1941            }
1942            block += new_blocks;
1943        }
1944        for (i = 0; i < bitmap->storage.file_pages; i++)
1945            set_page_attr(bitmap, i, BITMAP_PAGE_DIRTY);
1946    }
1947    spin_unlock_irq(&bitmap->counts.lock);
1948
1949    if (!init) {
1950        bitmap_unplug(bitmap);
1951        bitmap->mddev->pers->quiesce(bitmap->mddev, 0);
1952    }
1953    ret = 0;
1954err:
1955    return ret;
1956}
1957EXPORT_SYMBOL_GPL(bitmap_resize);
1958
1959static ssize_t
1960location_show(struct mddev *mddev, char *page)
1961{
1962    ssize_t len;
1963    if (mddev->bitmap_info.file)
1964        len = sprintf(page, "file");
1965    else if (mddev->bitmap_info.offset)
1966        len = sprintf(page, "%+lld", (long long)mddev->bitmap_info.offset);
1967    else
1968        len = sprintf(page, "none");
1969    len += sprintf(page+len, "\n");
1970    return len;
1971}
1972
1973static ssize_t
1974location_store(struct mddev *mddev, const char *buf, size_t len)
1975{
1976
1977    if (mddev->pers) {
1978        if (!mddev->pers->quiesce)
1979            return -EBUSY;
1980        if (mddev->recovery || mddev->sync_thread)
1981            return -EBUSY;
1982    }
1983
1984    if (mddev->bitmap || mddev->bitmap_info.file ||
1985        mddev->bitmap_info.offset) {
1986        /* bitmap already configured. Only option is to clear it */
1987        if (strncmp(buf, "none", 4) != 0)
1988            return -EBUSY;
1989        if (mddev->pers) {
1990            mddev->pers->quiesce(mddev, 1);
1991            bitmap_destroy(mddev);
1992            mddev->pers->quiesce(mddev, 0);
1993        }
1994        mddev->bitmap_info.offset = 0;
1995        if (mddev->bitmap_info.file) {
1996            struct file *f = mddev->bitmap_info.file;
1997            mddev->bitmap_info.file = NULL;
1998            restore_bitmap_write_access(f);
1999            fput(f);
2000        }
2001    } else {
2002        /* No bitmap, OK to set a location */
2003        long long offset;
2004        if (strncmp(buf, "none", 4) == 0)
2005            /* nothing to be done */;
2006        else if (strncmp(buf, "file:", 5) == 0) {
2007            /* Not supported yet */
2008            return -EINVAL;
2009        } else {
2010            int rv;
2011            if (buf[0] == '+')
2012                rv = strict_strtoll(buf+1, 10, &offset);
2013            else
2014                rv = strict_strtoll(buf, 10, &offset);
2015            if (rv)
2016                return rv;
2017            if (offset == 0)
2018                return -EINVAL;
2019            if (mddev->bitmap_info.external == 0 &&
2020                mddev->major_version == 0 &&
2021                offset != mddev->bitmap_info.default_offset)
2022                return -EINVAL;
2023            mddev->bitmap_info.offset = offset;
2024            if (mddev->pers) {
2025                mddev->pers->quiesce(mddev, 1);
2026                rv = bitmap_create(mddev);
2027                if (!rv)
2028                    rv = bitmap_load(mddev);
2029                if (rv) {
2030                    bitmap_destroy(mddev);
2031                    mddev->bitmap_info.offset = 0;
2032                }
2033                mddev->pers->quiesce(mddev, 0);
2034                if (rv)
2035                    return rv;
2036            }
2037        }
2038    }
2039    if (!mddev->external) {
2040        /* Ensure new bitmap info is stored in
2041         * metadata promptly.
2042         */
2043        set_bit(MD_CHANGE_DEVS, &mddev->flags);
2044        md_wakeup_thread(mddev->thread);
2045    }
2046    return len;
2047}
2048
2049static struct md_sysfs_entry bitmap_location =
2050__ATTR(location, S_IRUGO|S_IWUSR, location_show, location_store);
2051
2052/* 'bitmap/space' is the space available at 'location' for the
2053 * bitmap. This allows the kernel to know when it is safe to
2054 * resize the bitmap to match a resized array.
2055 */
2056static ssize_t
2057space_show(struct mddev *mddev, char *page)
2058{
2059    return sprintf(page, "%lu\n", mddev->bitmap_info.space);
2060}
2061
2062static ssize_t
2063space_store(struct mddev *mddev, const char *buf, size_t len)
2064{
2065    unsigned long sectors;
2066    int rv;
2067
2068    rv = kstrtoul(buf, 10, &sectors);
2069    if (rv)
2070        return rv;
2071
2072    if (sectors == 0)
2073        return -EINVAL;
2074
2075    if (mddev->bitmap &&
2076        sectors < (mddev->bitmap->storage.bytes + 511) >> 9)
2077        return -EFBIG; /* Bitmap is too big for this small space */
2078
2079    /* could make sure it isn't too big, but that isn't really
2080     * needed - user-space should be careful.
2081     */
2082    mddev->bitmap_info.space = sectors;
2083    return len;
2084}
2085
2086static struct md_sysfs_entry bitmap_space =
2087__ATTR(space, S_IRUGO|S_IWUSR, space_show, space_store);
2088
2089static ssize_t
2090timeout_show(struct mddev *mddev, char *page)
2091{
2092    ssize_t len;
2093    unsigned long secs = mddev->bitmap_info.daemon_sleep / HZ;
2094    unsigned long jifs = mddev->bitmap_info.daemon_sleep % HZ;
2095
2096    len = sprintf(page, "%lu", secs);
2097    if (jifs)
2098        len += sprintf(page+len, ".%03u", jiffies_to_msecs(jifs));
2099    len += sprintf(page+len, "\n");
2100    return len;
2101}
2102
2103static ssize_t
2104timeout_store(struct mddev *mddev, const char *buf, size_t len)
2105{
2106    /* timeout can be set at any time */
2107    unsigned long timeout;
2108    int rv = strict_strtoul_scaled(buf, &timeout, 4);
2109    if (rv)
2110        return rv;
2111
2112    /* just to make sure we don't overflow... */
2113    if (timeout >= LONG_MAX / HZ)
2114        return -EINVAL;
2115
2116    timeout = timeout * HZ / 10000;
2117
2118    if (timeout >= MAX_SCHEDULE_TIMEOUT)
2119        timeout = MAX_SCHEDULE_TIMEOUT-1;
2120    if (timeout < 1)
2121        timeout = 1;
2122    mddev->bitmap_info.daemon_sleep = timeout;
2123    if (mddev->thread) {
2124        /* if thread->timeout is MAX_SCHEDULE_TIMEOUT, then
2125         * the bitmap is all clean and we don't need to
2126         * adjust the timeout right now
2127         */
2128        if (mddev->thread->timeout < MAX_SCHEDULE_TIMEOUT) {
2129            mddev->thread->timeout = timeout;
2130            md_wakeup_thread(mddev->thread);
2131        }
2132    }
2133    return len;
2134}
2135
2136static struct md_sysfs_entry bitmap_timeout =
2137__ATTR(time_base, S_IRUGO|S_IWUSR, timeout_show, timeout_store);
2138
2139static ssize_t
2140backlog_show(struct mddev *mddev, char *page)
2141{
2142    return sprintf(page, "%lu\n", mddev->bitmap_info.max_write_behind);
2143}
2144
2145static ssize_t
2146backlog_store(struct mddev *mddev, const char *buf, size_t len)
2147{
2148    unsigned long backlog;
2149    int rv = strict_strtoul(buf, 10, &backlog);
2150    if (rv)
2151        return rv;
2152    if (backlog > COUNTER_MAX)
2153        return -EINVAL;
2154    mddev->bitmap_info.max_write_behind = backlog;
2155    return len;
2156}
2157
2158static struct md_sysfs_entry bitmap_backlog =
2159__ATTR(backlog, S_IRUGO|S_IWUSR, backlog_show, backlog_store);
2160
2161static ssize_t
2162chunksize_show(struct mddev *mddev, char *page)
2163{
2164    return sprintf(page, "%lu\n", mddev->bitmap_info.chunksize);
2165}
2166
2167static ssize_t
2168chunksize_store(struct mddev *mddev, const char *buf, size_t len)
2169{
2170    /* Can only be changed when no bitmap is active */
2171    int rv;
2172    unsigned long csize;
2173    if (mddev->bitmap)
2174        return -EBUSY;
2175    rv = strict_strtoul(buf, 10, &csize);
2176    if (rv)
2177        return rv;
2178    if (csize < 512 ||
2179        !is_power_of_2(csize))
2180        return -EINVAL;
2181    mddev->bitmap_info.chunksize = csize;
2182    return len;
2183}
2184
2185static struct md_sysfs_entry bitmap_chunksize =
2186__ATTR(chunksize, S_IRUGO|S_IWUSR, chunksize_show, chunksize_store);
2187
2188static ssize_t metadata_show(struct mddev *mddev, char *page)
2189{
2190    return sprintf(page, "%s\n", (mddev->bitmap_info.external
2191                      ? "external" : "internal"));
2192}
2193
2194static ssize_t metadata_store(struct mddev *mddev, const char *buf, size_t len)
2195{
2196    if (mddev->bitmap ||
2197        mddev->bitmap_info.file ||
2198        mddev->bitmap_info.offset)
2199        return -EBUSY;
2200    if (strncmp(buf, "external", 8) == 0)
2201        mddev->bitmap_info.external = 1;
2202    else if (strncmp(buf, "internal", 8) == 0)
2203        mddev->bitmap_info.external = 0;
2204    else
2205        return -EINVAL;
2206    return len;
2207}
2208
2209static struct md_sysfs_entry bitmap_metadata =
2210__ATTR(metadata, S_IRUGO|S_IWUSR, metadata_show, metadata_store);
2211
2212static ssize_t can_clear_show(struct mddev *mddev, char *page)
2213{
2214    int len;
2215    if (mddev->bitmap)
2216        len = sprintf(page, "%s\n", (mddev->bitmap->need_sync ?
2217                         "false" : "true"));
2218    else
2219        len = sprintf(page, "\n");
2220    return len;
2221}
2222
2223static ssize_t can_clear_store(struct mddev *mddev, const char *buf, size_t len)
2224{
2225    if (mddev->bitmap == NULL)
2226        return -ENOENT;
2227    if (strncmp(buf, "false", 5) == 0)
2228        mddev->bitmap->need_sync = 1;
2229    else if (strncmp(buf, "true", 4) == 0) {
2230        if (mddev->degraded)
2231            return -EBUSY;
2232        mddev->bitmap->need_sync = 0;
2233    } else
2234        return -EINVAL;
2235    return len;
2236}
2237
2238static struct md_sysfs_entry bitmap_can_clear =
2239__ATTR(can_clear, S_IRUGO|S_IWUSR, can_clear_show, can_clear_store);
2240
2241static ssize_t
2242behind_writes_used_show(struct mddev *mddev, char *page)
2243{
2244    if (mddev->bitmap == NULL)
2245        return sprintf(page, "0\n");
2246    return sprintf(page, "%lu\n",
2247               mddev->bitmap->behind_writes_used);
2248}
2249
2250static ssize_t
2251behind_writes_used_reset(struct mddev *mddev, const char *buf, size_t len)
2252{
2253    if (mddev->bitmap)
2254        mddev->bitmap->behind_writes_used = 0;
2255    return len;
2256}
2257
2258static struct md_sysfs_entry max_backlog_used =
2259__ATTR(max_backlog_used, S_IRUGO | S_IWUSR,
2260       behind_writes_used_show, behind_writes_used_reset);
2261
2262static struct attribute *md_bitmap_attrs[] = {
2263    &bitmap_location.attr,
2264    &bitmap_space.attr,
2265    &bitmap_timeout.attr,
2266    &bitmap_backlog.attr,
2267    &bitmap_chunksize.attr,
2268    &bitmap_metadata.attr,
2269    &bitmap_can_clear.attr,
2270    &max_backlog_used.attr,
2271    NULL
2272};
2273struct attribute_group md_bitmap_group = {
2274    .name = "bitmap",
2275    .attrs = md_bitmap_attrs,
2276};
2277
2278

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