Merge master.kernel.org:/pub/scm/linux/kernel/git/davej/agpgart
[linux-2.6] / 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  * - added bitmap daemon (to asynchronously clear bitmap bits from disk)
11  */
12
13 /*
14  * Still to do:
15  *
16  * flush after percent set rather than just time based. (maybe both).
17  * wait if count gets too high, wake when it drops to half.
18  * allow bitmap to be mirrored with superblock (before or after...)
19  * allow hot-add to re-instate a current device.
20  * allow hot-add of bitmap after quiessing device
21  */
22
23 #include <linux/module.h>
24 #include <linux/errno.h>
25 #include <linux/slab.h>
26 #include <linux/init.h>
27 #include <linux/config.h>
28 #include <linux/timer.h>
29 #include <linux/sched.h>
30 #include <linux/list.h>
31 #include <linux/file.h>
32 #include <linux/mount.h>
33 #include <linux/buffer_head.h>
34 #include <linux/raid/md.h>
35 #include <linux/raid/bitmap.h>
36
37 /* debug macros */
38
39 #define DEBUG 0
40
41 #if DEBUG
42 /* these are for debugging purposes only! */
43
44 /* define one and only one of these */
45 #define INJECT_FAULTS_1 0 /* cause bitmap_alloc_page to fail always */
46 #define INJECT_FAULTS_2 0 /* cause bitmap file to be kicked when first bit set*/
47 #define INJECT_FAULTS_3 0 /* treat bitmap file as kicked at init time */
48 #define INJECT_FAULTS_4 0 /* undef */
49 #define INJECT_FAULTS_5 0 /* undef */
50 #define INJECT_FAULTS_6 0
51
52 /* if these are defined, the driver will fail! debug only */
53 #define INJECT_FATAL_FAULT_1 0 /* fail kmalloc, causing bitmap_create to fail */
54 #define INJECT_FATAL_FAULT_2 0 /* undef */
55 #define INJECT_FATAL_FAULT_3 0 /* undef */
56 #endif
57
58 //#define DPRINTK PRINTK /* set this NULL to avoid verbose debug output */
59 #define DPRINTK(x...) do { } while(0)
60
61 #ifndef PRINTK
62 #  if DEBUG > 0
63 #    define PRINTK(x...) printk(KERN_DEBUG x)
64 #  else
65 #    define PRINTK(x...)
66 #  endif
67 #endif
68
69 static inline char * bmname(struct bitmap *bitmap)
70 {
71         return bitmap->mddev ? mdname(bitmap->mddev) : "mdX";
72 }
73
74
75 /*
76  * test if the bitmap is active
77  */
78 int bitmap_active(struct bitmap *bitmap)
79 {
80         unsigned long flags;
81         int res = 0;
82
83         if (!bitmap)
84                 return res;
85         spin_lock_irqsave(&bitmap->lock, flags);
86         res = bitmap->flags & BITMAP_ACTIVE;
87         spin_unlock_irqrestore(&bitmap->lock, flags);
88         return res;
89 }
90
91 #define WRITE_POOL_SIZE 256
92 /* mempool for queueing pending writes on the bitmap file */
93 static void *write_pool_alloc(gfp_t gfp_flags, void *data)
94 {
95         return kmalloc(sizeof(struct page_list), gfp_flags);
96 }
97
98 static void write_pool_free(void *ptr, void *data)
99 {
100         kfree(ptr);
101 }
102
103 /*
104  * just a placeholder - calls kmalloc for bitmap pages
105  */
106 static unsigned char *bitmap_alloc_page(struct bitmap *bitmap)
107 {
108         unsigned char *page;
109
110 #ifdef INJECT_FAULTS_1
111         page = NULL;
112 #else
113         page = kmalloc(PAGE_SIZE, GFP_NOIO);
114 #endif
115         if (!page)
116                 printk("%s: bitmap_alloc_page FAILED\n", bmname(bitmap));
117         else
118                 PRINTK("%s: bitmap_alloc_page: allocated page at %p\n",
119                         bmname(bitmap), page);
120         return page;
121 }
122
123 /*
124  * for now just a placeholder -- just calls kfree for bitmap pages
125  */
126 static void bitmap_free_page(struct bitmap *bitmap, unsigned char *page)
127 {
128         PRINTK("%s: bitmap_free_page: free page %p\n", bmname(bitmap), page);
129         kfree(page);
130 }
131
132 /*
133  * check a page and, if necessary, allocate it (or hijack it if the alloc fails)
134  *
135  * 1) check to see if this page is allocated, if it's not then try to alloc
136  * 2) if the alloc fails, set the page's hijacked flag so we'll use the
137  *    page pointer directly as a counter
138  *
139  * if we find our page, we increment the page's refcount so that it stays
140  * allocated while we're using it
141  */
142 static int bitmap_checkpage(struct bitmap *bitmap, unsigned long page, int create)
143 {
144         unsigned char *mappage;
145
146         if (page >= bitmap->pages) {
147                 printk(KERN_ALERT
148                         "%s: invalid bitmap page request: %lu (> %lu)\n",
149                         bmname(bitmap), page, bitmap->pages-1);
150                 return -EINVAL;
151         }
152
153
154         if (bitmap->bp[page].hijacked) /* it's hijacked, don't try to alloc */
155                 return 0;
156
157         if (bitmap->bp[page].map) /* page is already allocated, just return */
158                 return 0;
159
160         if (!create)
161                 return -ENOENT;
162
163         spin_unlock_irq(&bitmap->lock);
164
165         /* this page has not been allocated yet */
166
167         if ((mappage = bitmap_alloc_page(bitmap)) == NULL) {
168                 PRINTK("%s: bitmap map page allocation failed, hijacking\n",
169                         bmname(bitmap));
170                 /* failed - set the hijacked flag so that we can use the
171                  * pointer as a counter */
172                 spin_lock_irq(&bitmap->lock);
173                 if (!bitmap->bp[page].map)
174                         bitmap->bp[page].hijacked = 1;
175                 goto out;
176         }
177
178         /* got a page */
179
180         spin_lock_irq(&bitmap->lock);
181
182         /* recheck the page */
183
184         if (bitmap->bp[page].map || bitmap->bp[page].hijacked) {
185                 /* somebody beat us to getting the page */
186                 bitmap_free_page(bitmap, mappage);
187                 return 0;
188         }
189
190         /* no page was in place and we have one, so install it */
191
192         memset(mappage, 0, PAGE_SIZE);
193         bitmap->bp[page].map = mappage;
194         bitmap->missing_pages--;
195 out:
196         return 0;
197 }
198
199
200 /* if page is completely empty, put it back on the free list, or dealloc it */
201 /* if page was hijacked, unmark the flag so it might get alloced next time */
202 /* Note: lock should be held when calling this */
203 static void bitmap_checkfree(struct bitmap *bitmap, unsigned long page)
204 {
205         char *ptr;
206
207         if (bitmap->bp[page].count) /* page is still busy */
208                 return;
209
210         /* page is no longer in use, it can be released */
211
212         if (bitmap->bp[page].hijacked) { /* page was hijacked, undo this now */
213                 bitmap->bp[page].hijacked = 0;
214                 bitmap->bp[page].map = NULL;
215                 return;
216         }
217
218         /* normal case, free the page */
219
220 #if 0
221 /* actually ... let's not.  We will probably need the page again exactly when
222  * memory is tight and we are flusing to disk
223  */
224         return;
225 #else
226         ptr = bitmap->bp[page].map;
227         bitmap->bp[page].map = NULL;
228         bitmap->missing_pages++;
229         bitmap_free_page(bitmap, ptr);
230         return;
231 #endif
232 }
233
234
235 /*
236  * bitmap file handling - read and write the bitmap file and its superblock
237  */
238
239 /* copy the pathname of a file to a buffer */
240 char *file_path(struct file *file, char *buf, int count)
241 {
242         struct dentry *d;
243         struct vfsmount *v;
244
245         if (!buf)
246                 return NULL;
247
248         d = file->f_dentry;
249         v = file->f_vfsmnt;
250
251         buf = d_path(d, v, buf, count);
252
253         return IS_ERR(buf) ? NULL : buf;
254 }
255
256 /*
257  * basic page I/O operations
258  */
259
260 /* IO operations when bitmap is stored near all superblocks */
261 static struct page *read_sb_page(mddev_t *mddev, long offset, unsigned long index)
262 {
263         /* choose a good rdev and read the page from there */
264
265         mdk_rdev_t *rdev;
266         struct list_head *tmp;
267         struct page *page = alloc_page(GFP_KERNEL);
268         sector_t target;
269
270         if (!page)
271                 return ERR_PTR(-ENOMEM);
272
273         ITERATE_RDEV(mddev, rdev, tmp) {
274                 if (! test_bit(In_sync, &rdev->flags)
275                     || test_bit(Faulty, &rdev->flags))
276                         continue;
277
278                 target = (rdev->sb_offset << 1) + offset + index * (PAGE_SIZE/512);
279
280                 if (sync_page_io(rdev->bdev, target, PAGE_SIZE, page, READ)) {
281                         page->index = index;
282                         return page;
283                 }
284         }
285         return ERR_PTR(-EIO);
286
287 }
288
289 static int write_sb_page(mddev_t *mddev, long offset, struct page *page, int wait)
290 {
291         mdk_rdev_t *rdev;
292         struct list_head *tmp;
293
294         ITERATE_RDEV(mddev, rdev, tmp)
295                 if (test_bit(In_sync, &rdev->flags)
296                     && !test_bit(Faulty, &rdev->flags))
297                         md_super_write(mddev, rdev,
298                                        (rdev->sb_offset<<1) + offset
299                                        + page->index * (PAGE_SIZE/512),
300                                        PAGE_SIZE,
301                                        page);
302
303         if (wait)
304                 md_super_wait(mddev);
305         return 0;
306 }
307
308 /*
309  * write out a page to a file
310  */
311 static int write_page(struct bitmap *bitmap, struct page *page, int wait)
312 {
313         int ret = -ENOMEM;
314
315         if (bitmap->file == NULL)
316                 return write_sb_page(bitmap->mddev, bitmap->offset, page, wait);
317
318         flush_dcache_page(page); /* make sure visible to anyone reading the file */
319
320         if (wait)
321                 lock_page(page);
322         else {
323                 if (TestSetPageLocked(page))
324                         return -EAGAIN; /* already locked */
325                 if (PageWriteback(page)) {
326                         unlock_page(page);
327                         return -EAGAIN;
328                 }
329         }
330
331         ret = page->mapping->a_ops->prepare_write(bitmap->file, page, 0, PAGE_SIZE);
332         if (!ret)
333                 ret = page->mapping->a_ops->commit_write(bitmap->file, page, 0,
334                         PAGE_SIZE);
335         if (ret) {
336                 unlock_page(page);
337                 return ret;
338         }
339
340         set_page_dirty(page); /* force it to be written out */
341
342         if (!wait) {
343                 /* add to list to be waited for by daemon */
344                 struct page_list *item = mempool_alloc(bitmap->write_pool, GFP_NOIO);
345                 item->page = page;
346                 get_page(page);
347                 spin_lock(&bitmap->write_lock);
348                 list_add(&item->list, &bitmap->complete_pages);
349                 spin_unlock(&bitmap->write_lock);
350                 md_wakeup_thread(bitmap->writeback_daemon);
351         }
352         return write_one_page(page, wait);
353 }
354
355 /* read a page from a file, pinning it into cache, and return bytes_read */
356 static struct page *read_page(struct file *file, unsigned long index,
357                                         unsigned long *bytes_read)
358 {
359         struct inode *inode = file->f_mapping->host;
360         struct page *page = NULL;
361         loff_t isize = i_size_read(inode);
362         unsigned long end_index = isize >> PAGE_SHIFT;
363
364         PRINTK("read bitmap file (%dB @ %Lu)\n", (int)PAGE_SIZE,
365                         (unsigned long long)index << PAGE_SHIFT);
366
367         page = read_cache_page(inode->i_mapping, index,
368                         (filler_t *)inode->i_mapping->a_ops->readpage, file);
369         if (IS_ERR(page))
370                 goto out;
371         wait_on_page_locked(page);
372         if (!PageUptodate(page) || PageError(page)) {
373                 put_page(page);
374                 page = ERR_PTR(-EIO);
375                 goto out;
376         }
377
378         if (index > end_index) /* we have read beyond EOF */
379                 *bytes_read = 0;
380         else if (index == end_index) /* possible short read */
381                 *bytes_read = isize & ~PAGE_MASK;
382         else
383                 *bytes_read = PAGE_SIZE; /* got a full page */
384 out:
385         if (IS_ERR(page))
386                 printk(KERN_ALERT "md: bitmap read error: (%dB @ %Lu): %ld\n",
387                         (int)PAGE_SIZE,
388                         (unsigned long long)index << PAGE_SHIFT,
389                         PTR_ERR(page));
390         return page;
391 }
392
393 /*
394  * bitmap file superblock operations
395  */
396
397 /* update the event counter and sync the superblock to disk */
398 int bitmap_update_sb(struct bitmap *bitmap)
399 {
400         bitmap_super_t *sb;
401         unsigned long flags;
402
403         if (!bitmap || !bitmap->mddev) /* no bitmap for this array */
404                 return 0;
405         spin_lock_irqsave(&bitmap->lock, flags);
406         if (!bitmap->sb_page) { /* no superblock */
407                 spin_unlock_irqrestore(&bitmap->lock, flags);
408                 return 0;
409         }
410         spin_unlock_irqrestore(&bitmap->lock, flags);
411         sb = (bitmap_super_t *)kmap_atomic(bitmap->sb_page, KM_USER0);
412         sb->events = cpu_to_le64(bitmap->mddev->events);
413         if (!bitmap->mddev->degraded)
414                 sb->events_cleared = cpu_to_le64(bitmap->mddev->events);
415         kunmap_atomic(sb, KM_USER0);
416         return write_page(bitmap, bitmap->sb_page, 1);
417 }
418
419 /* print out the bitmap file superblock */
420 void bitmap_print_sb(struct bitmap *bitmap)
421 {
422         bitmap_super_t *sb;
423
424         if (!bitmap || !bitmap->sb_page)
425                 return;
426         sb = (bitmap_super_t *)kmap_atomic(bitmap->sb_page, KM_USER0);
427         printk(KERN_DEBUG "%s: bitmap file superblock:\n", bmname(bitmap));
428         printk(KERN_DEBUG "         magic: %08x\n", le32_to_cpu(sb->magic));
429         printk(KERN_DEBUG "       version: %d\n", le32_to_cpu(sb->version));
430         printk(KERN_DEBUG "          uuid: %08x.%08x.%08x.%08x\n",
431                                         *(__u32 *)(sb->uuid+0),
432                                         *(__u32 *)(sb->uuid+4),
433                                         *(__u32 *)(sb->uuid+8),
434                                         *(__u32 *)(sb->uuid+12));
435         printk(KERN_DEBUG "        events: %llu\n",
436                         (unsigned long long) le64_to_cpu(sb->events));
437         printk(KERN_DEBUG "events cleared: %llu\n",
438                         (unsigned long long) le64_to_cpu(sb->events_cleared));
439         printk(KERN_DEBUG "         state: %08x\n", le32_to_cpu(sb->state));
440         printk(KERN_DEBUG "     chunksize: %d B\n", le32_to_cpu(sb->chunksize));
441         printk(KERN_DEBUG "  daemon sleep: %ds\n", le32_to_cpu(sb->daemon_sleep));
442         printk(KERN_DEBUG "     sync size: %llu KB\n",
443                         (unsigned long long)le64_to_cpu(sb->sync_size)/2);
444         printk(KERN_DEBUG "max write behind: %d\n", le32_to_cpu(sb->write_behind));
445         kunmap_atomic(sb, KM_USER0);
446 }
447
448 /* read the superblock from the bitmap file and initialize some bitmap fields */
449 static int bitmap_read_sb(struct bitmap *bitmap)
450 {
451         char *reason = NULL;
452         bitmap_super_t *sb;
453         unsigned long chunksize, daemon_sleep, write_behind;
454         unsigned long bytes_read;
455         unsigned long long events;
456         int err = -EINVAL;
457
458         /* page 0 is the superblock, read it... */
459         if (bitmap->file)
460                 bitmap->sb_page = read_page(bitmap->file, 0, &bytes_read);
461         else {
462                 bitmap->sb_page = read_sb_page(bitmap->mddev, bitmap->offset, 0);
463                 bytes_read = PAGE_SIZE;
464         }
465         if (IS_ERR(bitmap->sb_page)) {
466                 err = PTR_ERR(bitmap->sb_page);
467                 bitmap->sb_page = NULL;
468                 return err;
469         }
470
471         sb = (bitmap_super_t *)kmap_atomic(bitmap->sb_page, KM_USER0);
472
473         if (bytes_read < sizeof(*sb)) { /* short read */
474                 printk(KERN_INFO "%s: bitmap file superblock truncated\n",
475                         bmname(bitmap));
476                 err = -ENOSPC;
477                 goto out;
478         }
479
480         chunksize = le32_to_cpu(sb->chunksize);
481         daemon_sleep = le32_to_cpu(sb->daemon_sleep);
482         write_behind = le32_to_cpu(sb->write_behind);
483
484         /* verify that the bitmap-specific fields are valid */
485         if (sb->magic != cpu_to_le32(BITMAP_MAGIC))
486                 reason = "bad magic";
487         else if (le32_to_cpu(sb->version) < BITMAP_MAJOR_LO ||
488                  le32_to_cpu(sb->version) > BITMAP_MAJOR_HI)
489                 reason = "unrecognized superblock version";
490         else if (chunksize < PAGE_SIZE)
491                 reason = "bitmap chunksize too small";
492         else if ((1 << ffz(~chunksize)) != chunksize)
493                 reason = "bitmap chunksize not a power of 2";
494         else if (daemon_sleep < 1 || daemon_sleep > MAX_SCHEDULE_TIMEOUT / HZ)
495                 reason = "daemon sleep period out of range";
496         else if (write_behind > COUNTER_MAX)
497                 reason = "write-behind limit out of range (0 - 16383)";
498         if (reason) {
499                 printk(KERN_INFO "%s: invalid bitmap file superblock: %s\n",
500                         bmname(bitmap), reason);
501                 goto out;
502         }
503
504         /* keep the array size field of the bitmap superblock up to date */
505         sb->sync_size = cpu_to_le64(bitmap->mddev->resync_max_sectors);
506
507         if (!bitmap->mddev->persistent)
508                 goto success;
509
510         /*
511          * if we have a persistent array superblock, compare the
512          * bitmap's UUID and event counter to the mddev's
513          */
514         if (memcmp(sb->uuid, bitmap->mddev->uuid, 16)) {
515                 printk(KERN_INFO "%s: bitmap superblock UUID mismatch\n",
516                         bmname(bitmap));
517                 goto out;
518         }
519         events = le64_to_cpu(sb->events);
520         if (events < bitmap->mddev->events) {
521                 printk(KERN_INFO "%s: bitmap file is out of date (%llu < %llu) "
522                         "-- forcing full recovery\n", bmname(bitmap), events,
523                         (unsigned long long) bitmap->mddev->events);
524                 sb->state |= BITMAP_STALE;
525         }
526 success:
527         /* assign fields using values from superblock */
528         bitmap->chunksize = chunksize;
529         bitmap->daemon_sleep = daemon_sleep;
530         bitmap->daemon_lastrun = jiffies;
531         bitmap->max_write_behind = write_behind;
532         bitmap->flags |= sb->state;
533         if (le32_to_cpu(sb->version) == BITMAP_MAJOR_HOSTENDIAN)
534                 bitmap->flags |= BITMAP_HOSTENDIAN;
535         bitmap->events_cleared = le64_to_cpu(sb->events_cleared);
536         if (sb->state & BITMAP_STALE)
537                 bitmap->events_cleared = bitmap->mddev->events;
538         err = 0;
539 out:
540         kunmap_atomic(sb, KM_USER0);
541         if (err)
542                 bitmap_print_sb(bitmap);
543         return err;
544 }
545
546 enum bitmap_mask_op {
547         MASK_SET,
548         MASK_UNSET
549 };
550
551 /* record the state of the bitmap in the superblock */
552 static void bitmap_mask_state(struct bitmap *bitmap, enum bitmap_state bits,
553                                 enum bitmap_mask_op op)
554 {
555         bitmap_super_t *sb;
556         unsigned long flags;
557
558         spin_lock_irqsave(&bitmap->lock, flags);
559         if (!bitmap->sb_page) { /* can't set the state */
560                 spin_unlock_irqrestore(&bitmap->lock, flags);
561                 return;
562         }
563         get_page(bitmap->sb_page);
564         spin_unlock_irqrestore(&bitmap->lock, flags);
565         sb = (bitmap_super_t *)kmap_atomic(bitmap->sb_page, KM_USER0);
566         switch (op) {
567                 case MASK_SET: sb->state |= bits;
568                                 break;
569                 case MASK_UNSET: sb->state &= ~bits;
570                                 break;
571                 default: BUG();
572         }
573         kunmap_atomic(sb, KM_USER0);
574         put_page(bitmap->sb_page);
575 }
576
577 /*
578  * general bitmap file operations
579  */
580
581 /* calculate the index of the page that contains this bit */
582 static inline unsigned long file_page_index(unsigned long chunk)
583 {
584         return CHUNK_BIT_OFFSET(chunk) >> PAGE_BIT_SHIFT;
585 }
586
587 /* calculate the (bit) offset of this bit within a page */
588 static inline unsigned long file_page_offset(unsigned long chunk)
589 {
590         return CHUNK_BIT_OFFSET(chunk) & (PAGE_BITS - 1);
591 }
592
593 /*
594  * return a pointer to the page in the filemap that contains the given bit
595  *
596  * this lookup is complicated by the fact that the bitmap sb might be exactly
597  * 1 page (e.g., x86) or less than 1 page -- so the bitmap might start on page
598  * 0 or page 1
599  */
600 static inline struct page *filemap_get_page(struct bitmap *bitmap,
601                                         unsigned long chunk)
602 {
603         return bitmap->filemap[file_page_index(chunk) - file_page_index(0)];
604 }
605
606
607 static void bitmap_file_unmap(struct bitmap *bitmap)
608 {
609         struct page **map, *sb_page;
610         unsigned long *attr;
611         int pages;
612         unsigned long flags;
613
614         spin_lock_irqsave(&bitmap->lock, flags);
615         map = bitmap->filemap;
616         bitmap->filemap = NULL;
617         attr = bitmap->filemap_attr;
618         bitmap->filemap_attr = NULL;
619         pages = bitmap->file_pages;
620         bitmap->file_pages = 0;
621         sb_page = bitmap->sb_page;
622         bitmap->sb_page = NULL;
623         spin_unlock_irqrestore(&bitmap->lock, flags);
624
625         while (pages--)
626                 if (map[pages]->index != 0) /* 0 is sb_page, release it below */
627                         put_page(map[pages]);
628         kfree(map);
629         kfree(attr);
630
631         safe_put_page(sb_page);
632 }
633
634 static void bitmap_stop_daemon(struct bitmap *bitmap);
635
636 /* dequeue the next item in a page list -- don't call from irq context */
637 static struct page_list *dequeue_page(struct bitmap *bitmap)
638 {
639         struct page_list *item = NULL;
640         struct list_head *head = &bitmap->complete_pages;
641
642         spin_lock(&bitmap->write_lock);
643         if (list_empty(head))
644                 goto out;
645         item = list_entry(head->prev, struct page_list, list);
646         list_del(head->prev);
647 out:
648         spin_unlock(&bitmap->write_lock);
649         return item;
650 }
651
652 static void drain_write_queues(struct bitmap *bitmap)
653 {
654         struct page_list *item;
655
656         while ((item = dequeue_page(bitmap))) {
657                 /* don't bother to wait */
658                 put_page(item->page);
659                 mempool_free(item, bitmap->write_pool);
660         }
661
662         wake_up(&bitmap->write_wait);
663 }
664
665 static void bitmap_file_put(struct bitmap *bitmap)
666 {
667         struct file *file;
668         struct inode *inode;
669         unsigned long flags;
670
671         spin_lock_irqsave(&bitmap->lock, flags);
672         file = bitmap->file;
673         bitmap->file = NULL;
674         spin_unlock_irqrestore(&bitmap->lock, flags);
675
676         bitmap_stop_daemon(bitmap);
677
678         drain_write_queues(bitmap);
679
680         bitmap_file_unmap(bitmap);
681
682         if (file) {
683                 inode = file->f_mapping->host;
684                 spin_lock(&inode->i_lock);
685                 atomic_set(&inode->i_writecount, 1); /* allow writes again */
686                 spin_unlock(&inode->i_lock);
687                 fput(file);
688         }
689 }
690
691
692 /*
693  * bitmap_file_kick - if an error occurs while manipulating the bitmap file
694  * then it is no longer reliable, so we stop using it and we mark the file
695  * as failed in the superblock
696  */
697 static void bitmap_file_kick(struct bitmap *bitmap)
698 {
699         char *path, *ptr = NULL;
700
701         bitmap_mask_state(bitmap, BITMAP_STALE, MASK_SET);
702         bitmap_update_sb(bitmap);
703
704         if (bitmap->file) {
705                 path = kmalloc(PAGE_SIZE, GFP_KERNEL);
706                 if (path)
707                         ptr = file_path(bitmap->file, path, PAGE_SIZE);
708
709                 printk(KERN_ALERT "%s: kicking failed bitmap file %s from array!\n",
710                        bmname(bitmap), ptr ? ptr : "");
711
712                 kfree(path);
713         }
714
715         bitmap_file_put(bitmap);
716
717         return;
718 }
719
720 enum bitmap_page_attr {
721         BITMAP_PAGE_DIRTY = 1, // there are set bits that need to be synced
722         BITMAP_PAGE_CLEAN = 2, // there are bits that might need to be cleared
723         BITMAP_PAGE_NEEDWRITE=4, // there are cleared bits that need to be synced
724 };
725
726 static inline void set_page_attr(struct bitmap *bitmap, struct page *page,
727                                 enum bitmap_page_attr attr)
728 {
729         bitmap->filemap_attr[page->index] |= attr;
730 }
731
732 static inline void clear_page_attr(struct bitmap *bitmap, struct page *page,
733                                 enum bitmap_page_attr attr)
734 {
735         bitmap->filemap_attr[page->index] &= ~attr;
736 }
737
738 static inline unsigned long get_page_attr(struct bitmap *bitmap, struct page *page)
739 {
740         return bitmap->filemap_attr[page->index];
741 }
742
743 /*
744  * bitmap_file_set_bit -- called before performing a write to the md device
745  * to set (and eventually sync) a particular bit in the bitmap file
746  *
747  * we set the bit immediately, then we record the page number so that
748  * when an unplug occurs, we can flush the dirty pages out to disk
749  */
750 static void bitmap_file_set_bit(struct bitmap *bitmap, sector_t block)
751 {
752         unsigned long bit;
753         struct page *page;
754         void *kaddr;
755         unsigned long chunk = block >> CHUNK_BLOCK_SHIFT(bitmap);
756
757         if (!bitmap->filemap) {
758                 return;
759         }
760
761         page = filemap_get_page(bitmap, chunk);
762         bit = file_page_offset(chunk);
763
764
765         /* make sure the page stays cached until it gets written out */
766         if (! (get_page_attr(bitmap, page) & BITMAP_PAGE_DIRTY))
767                 get_page(page);
768
769         /* set the bit */
770         kaddr = kmap_atomic(page, KM_USER0);
771         if (bitmap->flags & BITMAP_HOSTENDIAN)
772                 set_bit(bit, kaddr);
773         else
774                 ext2_set_bit(bit, kaddr);
775         kunmap_atomic(kaddr, KM_USER0);
776         PRINTK("set file bit %lu page %lu\n", bit, page->index);
777
778         /* record page number so it gets flushed to disk when unplug occurs */
779         set_page_attr(bitmap, page, BITMAP_PAGE_DIRTY);
780
781 }
782
783 /* this gets called when the md device is ready to unplug its underlying
784  * (slave) device queues -- before we let any writes go down, we need to
785  * sync the dirty pages of the bitmap file to disk */
786 int bitmap_unplug(struct bitmap *bitmap)
787 {
788         unsigned long i, attr, flags;
789         struct page *page;
790         int wait = 0;
791         int err;
792
793         if (!bitmap)
794                 return 0;
795
796         /* look at each page to see if there are any set bits that need to be
797          * flushed out to disk */
798         for (i = 0; i < bitmap->file_pages; i++) {
799                 spin_lock_irqsave(&bitmap->lock, flags);
800                 if (!bitmap->filemap) {
801                         spin_unlock_irqrestore(&bitmap->lock, flags);
802                         return 0;
803                 }
804                 page = bitmap->filemap[i];
805                 attr = get_page_attr(bitmap, page);
806                 clear_page_attr(bitmap, page, BITMAP_PAGE_DIRTY);
807                 clear_page_attr(bitmap, page, BITMAP_PAGE_NEEDWRITE);
808                 if ((attr & BITMAP_PAGE_DIRTY))
809                         wait = 1;
810                 spin_unlock_irqrestore(&bitmap->lock, flags);
811
812                 if (attr & (BITMAP_PAGE_DIRTY | BITMAP_PAGE_NEEDWRITE)) {
813                         err = write_page(bitmap, page, 0);
814                         if (err == -EAGAIN) {
815                                 if (attr & BITMAP_PAGE_DIRTY)
816                                         err = write_page(bitmap, page, 1);
817                                 else
818                                         err = 0;
819                         }
820                         if (err)
821                                 return 1;
822                 }
823         }
824         if (wait) { /* if any writes were performed, we need to wait on them */
825                 if (bitmap->file) {
826                         spin_lock_irq(&bitmap->write_lock);
827                         wait_event_lock_irq(bitmap->write_wait,
828                                             list_empty(&bitmap->complete_pages), bitmap->write_lock,
829                                             wake_up_process(bitmap->writeback_daemon->tsk));
830                         spin_unlock_irq(&bitmap->write_lock);
831                 } else
832                         md_super_wait(bitmap->mddev);
833         }
834         return 0;
835 }
836
837 static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset, int needed);
838 /* * bitmap_init_from_disk -- called at bitmap_create time to initialize
839  * the in-memory bitmap from the on-disk bitmap -- also, sets up the
840  * memory mapping of the bitmap file
841  * Special cases:
842  *   if there's no bitmap file, or if the bitmap file had been
843  *   previously kicked from the array, we mark all the bits as
844  *   1's in order to cause a full resync.
845  *
846  * We ignore all bits for sectors that end earlier than 'start'.
847  * This is used when reading an out-of-date bitmap...
848  */
849 static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
850 {
851         unsigned long i, chunks, index, oldindex, bit;
852         struct page *page = NULL, *oldpage = NULL;
853         unsigned long num_pages, bit_cnt = 0;
854         struct file *file;
855         unsigned long bytes, offset, dummy;
856         int outofdate;
857         int ret = -ENOSPC;
858         void *paddr;
859
860         chunks = bitmap->chunks;
861         file = bitmap->file;
862
863         BUG_ON(!file && !bitmap->offset);
864
865 #ifdef INJECT_FAULTS_3
866         outofdate = 1;
867 #else
868         outofdate = bitmap->flags & BITMAP_STALE;
869 #endif
870         if (outofdate)
871                 printk(KERN_INFO "%s: bitmap file is out of date, doing full "
872                         "recovery\n", bmname(bitmap));
873
874         bytes = (chunks + 7) / 8;
875
876         num_pages = (bytes + sizeof(bitmap_super_t) + PAGE_SIZE - 1) / PAGE_SIZE;
877
878         if (file && i_size_read(file->f_mapping->host) < bytes + sizeof(bitmap_super_t)) {
879                 printk(KERN_INFO "%s: bitmap file too short %lu < %lu\n",
880                         bmname(bitmap),
881                         (unsigned long) i_size_read(file->f_mapping->host),
882                         bytes + sizeof(bitmap_super_t));
883                 goto out;
884         }
885
886         ret = -ENOMEM;
887
888         bitmap->filemap = kmalloc(sizeof(struct page *) * num_pages, GFP_KERNEL);
889         if (!bitmap->filemap)
890                 goto out;
891
892         bitmap->filemap_attr = kzalloc(sizeof(long) * num_pages, GFP_KERNEL);
893         if (!bitmap->filemap_attr)
894                 goto out;
895
896         oldindex = ~0L;
897
898         for (i = 0; i < chunks; i++) {
899                 int b;
900                 index = file_page_index(i);
901                 bit = file_page_offset(i);
902                 if (index != oldindex) { /* this is a new page, read it in */
903                         /* unmap the old page, we're done with it */
904                         if (index == 0) {
905                                 /*
906                                  * if we're here then the superblock page
907                                  * contains some bits (PAGE_SIZE != sizeof sb)
908                                  * we've already read it in, so just use it
909                                  */
910                                 page = bitmap->sb_page;
911                                 offset = sizeof(bitmap_super_t);
912                         } else if (file) {
913                                 page = read_page(file, index, &dummy);
914                                 offset = 0;
915                         } else {
916                                 page = read_sb_page(bitmap->mddev, bitmap->offset, index);
917                                 offset = 0;
918                         }
919                         if (IS_ERR(page)) { /* read error */
920                                 ret = PTR_ERR(page);
921                                 goto out;
922                         }
923
924                         oldindex = index;
925                         oldpage = page;
926
927                         if (outofdate) {
928                                 /*
929                                  * if bitmap is out of date, dirty the
930                                  * whole page and write it out
931                                  */
932                                 paddr = kmap_atomic(page, KM_USER0);
933                                 memset(paddr + offset, 0xff,
934                                        PAGE_SIZE - offset);
935                                 kunmap_atomic(paddr, KM_USER0);
936                                 ret = write_page(bitmap, page, 1);
937                                 if (ret) {
938                                         /* release, page not in filemap yet */
939                                         put_page(page);
940                                         goto out;
941                                 }
942                         }
943
944                         bitmap->filemap[bitmap->file_pages++] = page;
945                 }
946                 paddr = kmap_atomic(page, KM_USER0);
947                 if (bitmap->flags & BITMAP_HOSTENDIAN)
948                         b = test_bit(bit, paddr);
949                 else
950                         b = ext2_test_bit(bit, paddr);
951                 kunmap_atomic(paddr, KM_USER0);
952                 if (b) {
953                         /* if the disk bit is set, set the memory bit */
954                         bitmap_set_memory_bits(bitmap, i << CHUNK_BLOCK_SHIFT(bitmap),
955                                                ((i+1) << (CHUNK_BLOCK_SHIFT(bitmap)) >= start)
956                                 );
957                         bit_cnt++;
958                         set_page_attr(bitmap, page, BITMAP_PAGE_CLEAN);
959                 }
960         }
961
962         /* everything went OK */
963         ret = 0;
964         bitmap_mask_state(bitmap, BITMAP_STALE, MASK_UNSET);
965
966         if (bit_cnt) { /* Kick recovery if any bits were set */
967                 set_bit(MD_RECOVERY_NEEDED, &bitmap->mddev->recovery);
968                 md_wakeup_thread(bitmap->mddev->thread);
969         }
970
971 out:
972         printk(KERN_INFO "%s: bitmap initialized from disk: "
973                 "read %lu/%lu pages, set %lu bits, status: %d\n",
974                 bmname(bitmap), bitmap->file_pages, num_pages, bit_cnt, ret);
975
976         return ret;
977 }
978
979 void bitmap_write_all(struct bitmap *bitmap)
980 {
981         /* We don't actually write all bitmap blocks here,
982          * just flag them as needing to be written
983          */
984
985         unsigned long chunks = bitmap->chunks;
986         unsigned long bytes = (chunks+7)/8 + sizeof(bitmap_super_t);
987         unsigned long num_pages = (bytes + PAGE_SIZE-1) / PAGE_SIZE;
988         while (num_pages--)
989                 bitmap->filemap_attr[num_pages] |= BITMAP_PAGE_NEEDWRITE;
990 }
991
992
993 static void bitmap_count_page(struct bitmap *bitmap, sector_t offset, int inc)
994 {
995         sector_t chunk = offset >> CHUNK_BLOCK_SHIFT(bitmap);
996         unsigned long page = chunk >> PAGE_COUNTER_SHIFT;
997         bitmap->bp[page].count += inc;
998 /*
999         if (page == 0) printk("count page 0, offset %llu: %d gives %d\n",
1000                               (unsigned long long)offset, inc, bitmap->bp[page].count);
1001 */
1002         bitmap_checkfree(bitmap, page);
1003 }
1004 static bitmap_counter_t *bitmap_get_counter(struct bitmap *bitmap,
1005                                             sector_t offset, int *blocks,
1006                                             int create);
1007
1008 /*
1009  * bitmap daemon -- periodically wakes up to clean bits and flush pages
1010  *                      out to disk
1011  */
1012
1013 int bitmap_daemon_work(struct bitmap *bitmap)
1014 {
1015         unsigned long j;
1016         unsigned long flags;
1017         struct page *page = NULL, *lastpage = NULL;
1018         int err = 0;
1019         int blocks;
1020         int attr;
1021         void *paddr;
1022
1023         if (bitmap == NULL)
1024                 return 0;
1025         if (time_before(jiffies, bitmap->daemon_lastrun + bitmap->daemon_sleep*HZ))
1026                 return 0;
1027         bitmap->daemon_lastrun = jiffies;
1028
1029         for (j = 0; j < bitmap->chunks; j++) {
1030                 bitmap_counter_t *bmc;
1031                 spin_lock_irqsave(&bitmap->lock, flags);
1032                 if (!bitmap->filemap) {
1033                         /* error or shutdown */
1034                         spin_unlock_irqrestore(&bitmap->lock, flags);
1035                         break;
1036                 }
1037
1038                 page = filemap_get_page(bitmap, j);
1039
1040                 if (page != lastpage) {
1041                         /* skip this page unless it's marked as needing cleaning */
1042                         if (!((attr=get_page_attr(bitmap, page)) & BITMAP_PAGE_CLEAN)) {
1043                                 if (attr & BITMAP_PAGE_NEEDWRITE) {
1044                                         get_page(page);
1045                                         clear_page_attr(bitmap, page, BITMAP_PAGE_NEEDWRITE);
1046                                 }
1047                                 spin_unlock_irqrestore(&bitmap->lock, flags);
1048                                 if (attr & BITMAP_PAGE_NEEDWRITE) {
1049                                         switch (write_page(bitmap, page, 0)) {
1050                                         case -EAGAIN:
1051                                                 set_page_attr(bitmap, page, BITMAP_PAGE_NEEDWRITE);
1052                                                 break;
1053                                         case 0:
1054                                                 break;
1055                                         default:
1056                                                 bitmap_file_kick(bitmap);
1057                                         }
1058                                         put_page(page);
1059                                 }
1060                                 continue;
1061                         }
1062
1063                         /* grab the new page, sync and release the old */
1064                         get_page(page);
1065                         if (lastpage != NULL) {
1066                                 if (get_page_attr(bitmap, lastpage) & BITMAP_PAGE_NEEDWRITE) {
1067                                         clear_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
1068                                         spin_unlock_irqrestore(&bitmap->lock, flags);
1069                                         err = write_page(bitmap, lastpage, 0);
1070                                         if (err == -EAGAIN) {
1071                                                 err = 0;
1072                                                 set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
1073                                         }
1074                                 } else {
1075                                         set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
1076                                         spin_unlock_irqrestore(&bitmap->lock, flags);
1077                                 }
1078                                 put_page(lastpage);
1079                                 if (err)
1080                                         bitmap_file_kick(bitmap);
1081                         } else
1082                                 spin_unlock_irqrestore(&bitmap->lock, flags);
1083                         lastpage = page;
1084 /*
1085                         printk("bitmap clean at page %lu\n", j);
1086 */
1087                         spin_lock_irqsave(&bitmap->lock, flags);
1088                         clear_page_attr(bitmap, page, BITMAP_PAGE_CLEAN);
1089                 }
1090                 bmc = bitmap_get_counter(bitmap, j << CHUNK_BLOCK_SHIFT(bitmap),
1091                                         &blocks, 0);
1092                 if (bmc) {
1093 /*
1094   if (j < 100) printk("bitmap: j=%lu, *bmc = 0x%x\n", j, *bmc);
1095 */
1096                         if (*bmc == 2) {
1097                                 *bmc=1; /* maybe clear the bit next time */
1098                                 set_page_attr(bitmap, page, BITMAP_PAGE_CLEAN);
1099                         } else if (*bmc == 1) {
1100                                 /* we can clear the bit */
1101                                 *bmc = 0;
1102                                 bitmap_count_page(bitmap, j << CHUNK_BLOCK_SHIFT(bitmap),
1103                                                   -1);
1104
1105                                 /* clear the bit */
1106                                 paddr = kmap_atomic(page, KM_USER0);
1107                                 if (bitmap->flags & BITMAP_HOSTENDIAN)
1108                                         clear_bit(file_page_offset(j), paddr);
1109                                 else
1110                                         ext2_clear_bit(file_page_offset(j), paddr);
1111                                 kunmap_atomic(paddr, KM_USER0);
1112                         }
1113                 }
1114                 spin_unlock_irqrestore(&bitmap->lock, flags);
1115         }
1116
1117         /* now sync the final page */
1118         if (lastpage != NULL) {
1119                 spin_lock_irqsave(&bitmap->lock, flags);
1120                 if (get_page_attr(bitmap, lastpage) &BITMAP_PAGE_NEEDWRITE) {
1121                         clear_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
1122                         spin_unlock_irqrestore(&bitmap->lock, flags);
1123                         err = write_page(bitmap, lastpage, 0);
1124                         if (err == -EAGAIN) {
1125                                 set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
1126                                 err = 0;
1127                         }
1128                 } else {
1129                         set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
1130                         spin_unlock_irqrestore(&bitmap->lock, flags);
1131                 }
1132
1133                 put_page(lastpage);
1134         }
1135
1136         return err;
1137 }
1138
1139 static void daemon_exit(struct bitmap *bitmap, mdk_thread_t **daemon)
1140 {
1141         mdk_thread_t *dmn;
1142         unsigned long flags;
1143
1144         /* if no one is waiting on us, we'll free the md thread struct
1145          * and exit, otherwise we let the waiter clean things up */
1146         spin_lock_irqsave(&bitmap->lock, flags);
1147         if ((dmn = *daemon)) { /* no one is waiting, cleanup and exit */
1148                 *daemon = NULL;
1149                 spin_unlock_irqrestore(&bitmap->lock, flags);
1150                 kfree(dmn);
1151                 complete_and_exit(NULL, 0); /* do_exit not exported */
1152         }
1153         spin_unlock_irqrestore(&bitmap->lock, flags);
1154 }
1155
1156 static void bitmap_writeback_daemon(mddev_t *mddev)
1157 {
1158         struct bitmap *bitmap = mddev->bitmap;
1159         struct page *page;
1160         struct page_list *item;
1161         int err = 0;
1162
1163         if (signal_pending(current)) {
1164                 printk(KERN_INFO
1165                        "%s: bitmap writeback daemon got signal, exiting...\n",
1166                        bmname(bitmap));
1167                 err = -EINTR;
1168                 goto out;
1169         }
1170         if (bitmap == NULL)
1171                 /* about to be stopped. */
1172                 return;
1173
1174         PRINTK("%s: bitmap writeback daemon woke up...\n", bmname(bitmap));
1175         /* wait on bitmap page writebacks */
1176         while ((item = dequeue_page(bitmap))) {
1177                 page = item->page;
1178                 mempool_free(item, bitmap->write_pool);
1179                 PRINTK("wait on page writeback: %p\n", page);
1180                 wait_on_page_writeback(page);
1181                 PRINTK("finished page writeback: %p\n", page);
1182
1183                 err = PageError(page);
1184                 put_page(page);
1185                 if (err) {
1186                         printk(KERN_WARNING "%s: bitmap file writeback "
1187                                "failed (page %lu): %d\n",
1188                                bmname(bitmap), page->index, err);
1189                         bitmap_file_kick(bitmap);
1190                         goto out;
1191                 }
1192         }
1193  out:
1194         wake_up(&bitmap->write_wait);
1195         if (err) {
1196                 printk(KERN_INFO "%s: bitmap writeback daemon exiting (%d)\n",
1197                        bmname(bitmap), err);
1198                 daemon_exit(bitmap, &bitmap->writeback_daemon);
1199         }
1200 }
1201
1202 static mdk_thread_t *bitmap_start_daemon(struct bitmap *bitmap,
1203                                 void (*func)(mddev_t *), char *name)
1204 {
1205         mdk_thread_t *daemon;
1206         char namebuf[32];
1207
1208 #ifdef INJECT_FATAL_FAULT_2
1209         daemon = NULL;
1210 #else
1211         sprintf(namebuf, "%%s_%s", name);
1212         daemon = md_register_thread(func, bitmap->mddev, namebuf);
1213 #endif
1214         if (!daemon) {
1215                 printk(KERN_ERR "%s: failed to start bitmap daemon\n",
1216                         bmname(bitmap));
1217                 return ERR_PTR(-ECHILD);
1218         }
1219
1220         md_wakeup_thread(daemon); /* start it running */
1221
1222         PRINTK("%s: %s daemon (pid %d) started...\n",
1223                 bmname(bitmap), name, daemon->tsk->pid);
1224
1225         return daemon;
1226 }
1227
1228 static void bitmap_stop_daemon(struct bitmap *bitmap)
1229 {
1230         /* the daemon can't stop itself... it'll just exit instead... */
1231         if (bitmap->writeback_daemon && ! IS_ERR(bitmap->writeback_daemon) &&
1232             current->pid != bitmap->writeback_daemon->tsk->pid) {
1233                 mdk_thread_t *daemon;
1234                 unsigned long flags;
1235
1236                 spin_lock_irqsave(&bitmap->lock, flags);
1237                 daemon = bitmap->writeback_daemon;
1238                 bitmap->writeback_daemon = NULL;
1239                 spin_unlock_irqrestore(&bitmap->lock, flags);
1240                 if (daemon && ! IS_ERR(daemon))
1241                         md_unregister_thread(daemon); /* destroy the thread */
1242         }
1243 }
1244
1245 static bitmap_counter_t *bitmap_get_counter(struct bitmap *bitmap,
1246                                             sector_t offset, int *blocks,
1247                                             int create)
1248 {
1249         /* If 'create', we might release the lock and reclaim it.
1250          * The lock must have been taken with interrupts enabled.
1251          * If !create, we don't release the lock.
1252          */
1253         sector_t chunk = offset >> CHUNK_BLOCK_SHIFT(bitmap);
1254         unsigned long page = chunk >> PAGE_COUNTER_SHIFT;
1255         unsigned long pageoff = (chunk & PAGE_COUNTER_MASK) << COUNTER_BYTE_SHIFT;
1256         sector_t csize;
1257
1258         if (bitmap_checkpage(bitmap, page, create) < 0) {
1259                 csize = ((sector_t)1) << (CHUNK_BLOCK_SHIFT(bitmap));
1260                 *blocks = csize - (offset & (csize- 1));
1261                 return NULL;
1262         }
1263         /* now locked ... */
1264
1265         if (bitmap->bp[page].hijacked) { /* hijacked pointer */
1266                 /* should we use the first or second counter field
1267                  * of the hijacked pointer? */
1268                 int hi = (pageoff > PAGE_COUNTER_MASK);
1269                 csize = ((sector_t)1) << (CHUNK_BLOCK_SHIFT(bitmap) +
1270                                           PAGE_COUNTER_SHIFT - 1);
1271                 *blocks = csize - (offset & (csize- 1));
1272                 return  &((bitmap_counter_t *)
1273                           &bitmap->bp[page].map)[hi];
1274         } else { /* page is allocated */
1275                 csize = ((sector_t)1) << (CHUNK_BLOCK_SHIFT(bitmap));
1276                 *blocks = csize - (offset & (csize- 1));
1277                 return (bitmap_counter_t *)
1278                         &(bitmap->bp[page].map[pageoff]);
1279         }
1280 }
1281
1282 int bitmap_startwrite(struct bitmap *bitmap, sector_t offset, unsigned long sectors, int behind)
1283 {
1284         if (!bitmap) return 0;
1285
1286         if (behind) {
1287                 atomic_inc(&bitmap->behind_writes);
1288                 PRINTK(KERN_DEBUG "inc write-behind count %d/%d\n",
1289                   atomic_read(&bitmap->behind_writes), bitmap->max_write_behind);
1290         }
1291
1292         while (sectors) {
1293                 int blocks;
1294                 bitmap_counter_t *bmc;
1295
1296                 spin_lock_irq(&bitmap->lock);
1297                 bmc = bitmap_get_counter(bitmap, offset, &blocks, 1);
1298                 if (!bmc) {
1299                         spin_unlock_irq(&bitmap->lock);
1300                         return 0;
1301                 }
1302
1303                 switch(*bmc) {
1304                 case 0:
1305                         bitmap_file_set_bit(bitmap, offset);
1306                         bitmap_count_page(bitmap,offset, 1);
1307                         blk_plug_device(bitmap->mddev->queue);
1308                         /* fall through */
1309                 case 1:
1310                         *bmc = 2;
1311                 }
1312                 BUG_ON((*bmc & COUNTER_MAX) == COUNTER_MAX);
1313                 (*bmc)++;
1314
1315                 spin_unlock_irq(&bitmap->lock);
1316
1317                 offset += blocks;
1318                 if (sectors > blocks)
1319                         sectors -= blocks;
1320                 else sectors = 0;
1321         }
1322         return 0;
1323 }
1324
1325 void bitmap_endwrite(struct bitmap *bitmap, sector_t offset, unsigned long sectors,
1326                      int success, int behind)
1327 {
1328         if (!bitmap) return;
1329         if (behind) {
1330                 atomic_dec(&bitmap->behind_writes);
1331                 PRINTK(KERN_DEBUG "dec write-behind count %d/%d\n",
1332                   atomic_read(&bitmap->behind_writes), bitmap->max_write_behind);
1333         }
1334
1335         while (sectors) {
1336                 int blocks;
1337                 unsigned long flags;
1338                 bitmap_counter_t *bmc;
1339
1340                 spin_lock_irqsave(&bitmap->lock, flags);
1341                 bmc = bitmap_get_counter(bitmap, offset, &blocks, 0);
1342                 if (!bmc) {
1343                         spin_unlock_irqrestore(&bitmap->lock, flags);
1344                         return;
1345                 }
1346
1347                 if (!success && ! (*bmc & NEEDED_MASK))
1348                         *bmc |= NEEDED_MASK;
1349
1350                 (*bmc)--;
1351                 if (*bmc <= 2) {
1352                         set_page_attr(bitmap,
1353                                       filemap_get_page(bitmap, offset >> CHUNK_BLOCK_SHIFT(bitmap)),
1354                                       BITMAP_PAGE_CLEAN);
1355                 }
1356                 spin_unlock_irqrestore(&bitmap->lock, flags);
1357                 offset += blocks;
1358                 if (sectors > blocks)
1359                         sectors -= blocks;
1360                 else sectors = 0;
1361         }
1362 }
1363
1364 int bitmap_start_sync(struct bitmap *bitmap, sector_t offset, int *blocks,
1365                         int degraded)
1366 {
1367         bitmap_counter_t *bmc;
1368         int rv;
1369         if (bitmap == NULL) {/* FIXME or bitmap set as 'failed' */
1370                 *blocks = 1024;
1371                 return 1; /* always resync if no bitmap */
1372         }
1373         spin_lock_irq(&bitmap->lock);
1374         bmc = bitmap_get_counter(bitmap, offset, blocks, 0);
1375         rv = 0;
1376         if (bmc) {
1377                 /* locked */
1378                 if (RESYNC(*bmc))
1379                         rv = 1;
1380                 else if (NEEDED(*bmc)) {
1381                         rv = 1;
1382                         if (!degraded) { /* don't set/clear bits if degraded */
1383                                 *bmc |= RESYNC_MASK;
1384                                 *bmc &= ~NEEDED_MASK;
1385                         }
1386                 }
1387         }
1388         spin_unlock_irq(&bitmap->lock);
1389         return rv;
1390 }
1391
1392 void bitmap_end_sync(struct bitmap *bitmap, sector_t offset, int *blocks, int aborted)
1393 {
1394         bitmap_counter_t *bmc;
1395         unsigned long flags;
1396 /*
1397         if (offset == 0) printk("bitmap_end_sync 0 (%d)\n", aborted);
1398 */      if (bitmap == NULL) {
1399                 *blocks = 1024;
1400                 return;
1401         }
1402         spin_lock_irqsave(&bitmap->lock, flags);
1403         bmc = bitmap_get_counter(bitmap, offset, blocks, 0);
1404         if (bmc == NULL)
1405                 goto unlock;
1406         /* locked */
1407 /*
1408         if (offset == 0) printk("bitmap_end sync found 0x%x, blocks %d\n", *bmc, *blocks);
1409 */
1410         if (RESYNC(*bmc)) {
1411                 *bmc &= ~RESYNC_MASK;
1412
1413                 if (!NEEDED(*bmc) && aborted)
1414                         *bmc |= NEEDED_MASK;
1415                 else {
1416                         if (*bmc <= 2) {
1417                                 set_page_attr(bitmap,
1418                                               filemap_get_page(bitmap, offset >> CHUNK_BLOCK_SHIFT(bitmap)),
1419                                               BITMAP_PAGE_CLEAN);
1420                         }
1421                 }
1422         }
1423  unlock:
1424         spin_unlock_irqrestore(&bitmap->lock, flags);
1425 }
1426
1427 void bitmap_close_sync(struct bitmap *bitmap)
1428 {
1429         /* Sync has finished, and any bitmap chunks that weren't synced
1430          * properly have been aborted.  It remains to us to clear the
1431          * RESYNC bit wherever it is still on
1432          */
1433         sector_t sector = 0;
1434         int blocks;
1435         if (!bitmap) return;
1436         while (sector < bitmap->mddev->resync_max_sectors) {
1437                 bitmap_end_sync(bitmap, sector, &blocks, 0);
1438 /*
1439                 if (sector < 500) printk("bitmap_close_sync: sec %llu blks %d\n",
1440                                          (unsigned long long)sector, blocks);
1441 */              sector += blocks;
1442         }
1443 }
1444
1445 static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset, int needed)
1446 {
1447         /* For each chunk covered by any of these sectors, set the
1448          * counter to 1 and set resync_needed.  They should all
1449          * be 0 at this point
1450          */
1451
1452         int secs;
1453         bitmap_counter_t *bmc;
1454         spin_lock_irq(&bitmap->lock);
1455         bmc = bitmap_get_counter(bitmap, offset, &secs, 1);
1456         if (!bmc) {
1457                 spin_unlock_irq(&bitmap->lock);
1458                 return;
1459         }
1460         if (! *bmc) {
1461                 struct page *page;
1462                 *bmc = 1 | (needed?NEEDED_MASK:0);
1463                 bitmap_count_page(bitmap, offset, 1);
1464                 page = filemap_get_page(bitmap, offset >> CHUNK_BLOCK_SHIFT(bitmap));
1465                 set_page_attr(bitmap, page, BITMAP_PAGE_CLEAN);
1466         }
1467         spin_unlock_irq(&bitmap->lock);
1468
1469 }
1470
1471 /*
1472  * flush out any pending updates
1473  */
1474 void bitmap_flush(mddev_t *mddev)
1475 {
1476         struct bitmap *bitmap = mddev->bitmap;
1477         int sleep;
1478
1479         if (!bitmap) /* there was no bitmap */
1480                 return;
1481
1482         /* run the daemon_work three time to ensure everything is flushed
1483          * that can be
1484          */
1485         sleep = bitmap->daemon_sleep;
1486         bitmap->daemon_sleep = 0;
1487         bitmap_daemon_work(bitmap);
1488         bitmap_daemon_work(bitmap);
1489         bitmap_daemon_work(bitmap);
1490         bitmap->daemon_sleep = sleep;
1491         bitmap_update_sb(bitmap);
1492 }
1493
1494 /*
1495  * free memory that was allocated
1496  */
1497 static void bitmap_free(struct bitmap *bitmap)
1498 {
1499         unsigned long k, pages;
1500         struct bitmap_page *bp;
1501
1502         if (!bitmap) /* there was no bitmap */
1503                 return;
1504
1505         /* release the bitmap file and kill the daemon */
1506         bitmap_file_put(bitmap);
1507
1508         bp = bitmap->bp;
1509         pages = bitmap->pages;
1510
1511         /* free all allocated memory */
1512
1513         mempool_destroy(bitmap->write_pool);
1514
1515         if (bp) /* deallocate the page memory */
1516                 for (k = 0; k < pages; k++)
1517                         if (bp[k].map && !bp[k].hijacked)
1518                                 kfree(bp[k].map);
1519         kfree(bp);
1520         kfree(bitmap);
1521 }
1522 void bitmap_destroy(mddev_t *mddev)
1523 {
1524         struct bitmap *bitmap = mddev->bitmap;
1525
1526         if (!bitmap) /* there was no bitmap */
1527                 return;
1528
1529         mddev->bitmap = NULL; /* disconnect from the md device */
1530         if (mddev->thread)
1531                 mddev->thread->timeout = MAX_SCHEDULE_TIMEOUT;
1532
1533         bitmap_free(bitmap);
1534 }
1535
1536 /*
1537  * initialize the bitmap structure
1538  * if this returns an error, bitmap_destroy must be called to do clean up
1539  */
1540 int bitmap_create(mddev_t *mddev)
1541 {
1542         struct bitmap *bitmap;
1543         unsigned long blocks = mddev->resync_max_sectors;
1544         unsigned long chunks;
1545         unsigned long pages;
1546         struct file *file = mddev->bitmap_file;
1547         int err;
1548         sector_t start;
1549
1550         BUG_ON(sizeof(bitmap_super_t) != 256);
1551
1552         if (!file && !mddev->bitmap_offset) /* bitmap disabled, nothing to do */
1553                 return 0;
1554
1555         BUG_ON(file && mddev->bitmap_offset);
1556
1557         bitmap = kzalloc(sizeof(*bitmap), GFP_KERNEL);
1558         if (!bitmap)
1559                 return -ENOMEM;
1560
1561         spin_lock_init(&bitmap->lock);
1562         bitmap->mddev = mddev;
1563
1564         spin_lock_init(&bitmap->write_lock);
1565         INIT_LIST_HEAD(&bitmap->complete_pages);
1566         init_waitqueue_head(&bitmap->write_wait);
1567         bitmap->write_pool = mempool_create(WRITE_POOL_SIZE, write_pool_alloc,
1568                                 write_pool_free, NULL);
1569         err = -ENOMEM;
1570         if (!bitmap->write_pool)
1571                 goto error;
1572
1573         bitmap->file = file;
1574         bitmap->offset = mddev->bitmap_offset;
1575         if (file) get_file(file);
1576         /* read superblock from bitmap file (this sets bitmap->chunksize) */
1577         err = bitmap_read_sb(bitmap);
1578         if (err)
1579                 goto error;
1580
1581         bitmap->chunkshift = find_first_bit(&bitmap->chunksize,
1582                                         sizeof(bitmap->chunksize));
1583
1584         /* now that chunksize and chunkshift are set, we can use these macros */
1585         chunks = (blocks + CHUNK_BLOCK_RATIO(bitmap) - 1) /
1586                         CHUNK_BLOCK_RATIO(bitmap);
1587         pages = (chunks + PAGE_COUNTER_RATIO - 1) / PAGE_COUNTER_RATIO;
1588
1589         BUG_ON(!pages);
1590
1591         bitmap->chunks = chunks;
1592         bitmap->pages = pages;
1593         bitmap->missing_pages = pages;
1594         bitmap->counter_bits = COUNTER_BITS;
1595
1596         bitmap->syncchunk = ~0UL;
1597
1598 #ifdef INJECT_FATAL_FAULT_1
1599         bitmap->bp = NULL;
1600 #else
1601         bitmap->bp = kzalloc(pages * sizeof(*bitmap->bp), GFP_KERNEL);
1602 #endif
1603         err = -ENOMEM;
1604         if (!bitmap->bp)
1605                 goto error;
1606
1607         bitmap->flags |= BITMAP_ACTIVE;
1608
1609         /* now that we have some pages available, initialize the in-memory
1610          * bitmap from the on-disk bitmap */
1611         start = 0;
1612         if (mddev->degraded == 0
1613             || bitmap->events_cleared == mddev->events)
1614                 /* no need to keep dirty bits to optimise a re-add of a missing device */
1615                 start = mddev->recovery_cp;
1616         err = bitmap_init_from_disk(bitmap, start);
1617
1618         if (err)
1619                 goto error;
1620
1621         printk(KERN_INFO "created bitmap (%lu pages) for device %s\n",
1622                 pages, bmname(bitmap));
1623
1624         mddev->bitmap = bitmap;
1625
1626         if (file)
1627                 /* kick off the bitmap writeback daemon */
1628                 bitmap->writeback_daemon =
1629                         bitmap_start_daemon(bitmap,
1630                                             bitmap_writeback_daemon,
1631                                             "bitmap_wb");
1632
1633         if (IS_ERR(bitmap->writeback_daemon))
1634                 return PTR_ERR(bitmap->writeback_daemon);
1635         mddev->thread->timeout = bitmap->daemon_sleep * HZ;
1636
1637         return bitmap_update_sb(bitmap);
1638
1639  error:
1640         bitmap_free(bitmap);
1641         return err;
1642 }
1643
1644 /* the bitmap API -- for raid personalities */
1645 EXPORT_SYMBOL(bitmap_startwrite);
1646 EXPORT_SYMBOL(bitmap_endwrite);
1647 EXPORT_SYMBOL(bitmap_start_sync);
1648 EXPORT_SYMBOL(bitmap_end_sync);
1649 EXPORT_SYMBOL(bitmap_unplug);
1650 EXPORT_SYMBOL(bitmap_close_sync);
1651 EXPORT_SYMBOL(bitmap_daemon_work);