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