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