drivers/md/bitmap.c

   1 /*
   2  * bitmap.c two-level bitmap (C) Peter T. Breuer (ptb@ot.uc3m.es) 2003
   3  *
   4  * bitmap_create  - sets up the bitmap structure
   5  * bitmap_destroy - destroys the bitmap structure
   6  *
   7  * additions, Copyright (C) 2003-2004, Paul Clements, SteelEye Technology, Inc.:
   8  * - added disk storage for bitmap
   9  * - changes to allow various bitmap chunk sizes
  10  * - added bitmap daemon (to asynchronously clear bitmap bits from disk)
  11  */
  12
  13 /*
  14  * Still to do:
  15  *
  16  * flush after percent set rather than just time based. (maybe both).
  17  * wait if count gets too high, wake when it drops to half.
  18  * allow bitmap to be mirrored with superblock (before or after...)
  19  * allow hot-add to re-instate a current device.
  20  * allow hot-add of bitmap after quiessing device
  21  */
  22
  23 #include <linux/module.h>
  24 #include <linux/errno.h>
  25 #include <linux/slab.h>
  26 #include <linux/init.h>
  27 #include <linux/config.h>
  28 #include <linux/timer.h>
  29 #include <linux/sched.h>
  30 #include <linux/list.h>
  31 #include <linux/file.h>
  32 #include <linux/mount.h>
  33 #include <linux/buffer_head.h>
  34 #include <linux/raid/md.h>
  35 #include <linux/raid/bitmap.h>
  36
  37 /* debug macros */
  38
  39 #define DEBUG 0
  40
  41 #if DEBUG
  42 /* these are for debugging purposes only! */
  43
  44 /* define one and only one of these */
  45 #define INJECT_FAULTS_1 0 /* cause bitmap_alloc_page to fail always */
  46 #define INJECT_FAULTS_2 0 /* cause bitmap file to be kicked when first bit set*/
  47 #define INJECT_FAULTS_3 0 /* treat bitmap file as kicked at init time */
  48 #define INJECT_FAULTS_4 0 /* undef */
  49 #define INJECT_FAULTS_5 0 /* undef */
  50 #define INJECT_FAULTS_6 0
  51
  52 /* if these are defined, the driver will fail! debug only */
  53 #define INJECT_FATAL_FAULT_1 0 /* fail kmalloc, causing bitmap_create to fail */
  54 #define INJECT_FATAL_FAULT_2 0 /* undef */
  55 #define INJECT_FATAL_FAULT_3 0 /* undef */
  56 #endif
  57
  58 //#define DPRINTK PRINTK /* set this NULL to avoid verbose debug output */
  59 #define DPRINTK(x...) do { } while(0)
  60
  61 #ifndef PRINTK
  62 #  if DEBUG > 0
  63 #    define PRINTK(x...) printk(KERN_DEBUG x)
  64 #  else
  65 #    define PRINTK(x...)
  66 #  endif
  67 #endif
  68
  69 static inline char * bmname(struct bitmap *bitmap)
  70 {
  71         return bitmap->mddev ? mdname(bitmap->mddev) : "mdX";
  72 }
  73
  74
  75 /*
  76  * test if the bitmap is active
  77  */
  78 int bitmap_active(struct bitmap *bitmap)
  79 {
  80         unsigned long flags;
  81         int res = 0;
  82
  83         if (!bitmap)
  84                 return res;
  85         spin_lock_irqsave(&bitmap->lock, flags);
  86         res = bitmap->flags & BITMAP_ACTIVE;
  87         spin_unlock_irqrestore(&bitmap->lock, flags);
  88         return res;
  89 }
  90
  91 #define WRITE_POOL_SIZE 256
  92 /* mempool for queueing pending writes on the bitmap file */
  93 static void *write_pool_alloc(gfp_t gfp_flags, void *data)
  94 {
  95         return kmalloc(sizeof(struct page_list), gfp_flags);
  96 }
  97
  98 static void write_pool_free(void *ptr, void *data)
  99 {
 100         kfree(ptr);
 101 }
 102
 103 /*
 104  * just a placeholder - calls kmalloc for bitmap pages
 105  */
 106 static unsigned char *bitmap_alloc_page(struct bitmap *bitmap)
 107 {
 108         unsigned char *page;
 109
 110 #ifdef INJECT_FAULTS_1
 111         page = NULL;
 112 #else
 113         page = kmalloc(PAGE_SIZE, GFP_NOIO);
 114 #endif
 115         if (!page)
 116                 printk("%s: bitmap_alloc_page FAILED\n", bmname(bitmap));
 117         else
 118                 PRINTK("%s: bitmap_alloc_page: allocated page at %p\n",
 119                         bmname(bitmap), page);
 120         return page;
 121 }
 122
 123 /*
 124  * for now just a placeholder -- just calls kfree for bitmap pages
 125  */
 126 static void bitmap_free_page(struct bitmap *bitmap, unsigned char *page)
 127 {
 128         PRINTK("%s: bitmap_free_page: free page %p\n", bmname(bitmap), page);
 129         kfree(page);
 130 }
 131
 132 /*
 133  * check a page and, if necessary, allocate it (or hijack it if the alloc fails)
 134  *
 135  * 1) check to see if this page is allocated, if it's not then try to alloc
 136  * 2) if the alloc fails, set the page's hijacked flag so we'll use the
 137  *    page pointer directly as a counter
 138  *
 139  * if we find our page, we increment the page's refcount so that it stays
 140  * allocated while we're using it
 141  */
 142 static int bitmap_checkpage(struct bitmap *bitmap, unsigned long page, int create)
 143 {
 144         unsigned char *mappage;
 145
 146         if (page >= bitmap->pages) {
 147                 printk(KERN_ALERT
 148                         "%s: invalid bitmap page request: %lu (> %lu)\n",
 149                         bmname(bitmap), page, bitmap->pages-1);
 150                 return -EINVAL;
 151         }
 152
 153
 154         if (bitmap->bp[page].hijacked) /* it's hijacked, don't try to alloc */
 155                 return 0;
 156
 157         if (bitmap->bp[page].map) /* page is already allocated, just return */
 158                 return 0;
 159
 160         if (!create)
 161                 return -ENOENT;
 162
 163         spin_unlock_irq(&bitmap->lock);
 164
 165         /* this page has not been allocated yet */
 166
 167         if ((mappage = bitmap_alloc_page(bitmap)) == NULL) {
 168                 PRINTK("%s: bitmap map page allocation failed, hijacking\n",
 169                         bmname(bitmap));
 170                 /* failed - set the hijacked flag so that we can use the
 171                  * pointer as a counter */
 172                 spin_lock_irq(&bitmap->lock);
 173                 if (!bitmap->bp[page].map)
 174                         bitmap->bp[page].hijacked = 1;
 175                 goto out;
 176         }
 177
 178         /* got a page */
 179
 180         spin_lock_irq(&bitmap->lock);
 181
 182         /* recheck the page */
 183
 184         if (bitmap->bp[page].map || bitmap->bp[page].hijacked) {
 185                 /* somebody beat us to getting the page */
 186                 bitmap_free_page(bitmap, mappage);
 187                 return 0;
 188         }
 189
 190         /* no page was in place and we have one, so install it */
 191
 192         memset(mappage, 0, PAGE_SIZE);
 193         bitmap->bp[page].map = mappage;
 194         bitmap->missing_pages--;
 195 out:
 196         return 0;
 197 }
 198
 199
 200 /* if page is completely empty, put it back on the free list, or dealloc it */
 201 /* if page was hijacked, unmark the flag so it might get alloced next time */
 202 /* Note: lock should be held when calling this */
 203 static void bitmap_checkfree(struct bitmap *bitmap, unsigned long page)
 204 {
 205         char *ptr;
 206
 207         if (bitmap->bp[page].count) /* page is still busy */
 208                 return;
 209
 210         /* page is no longer in use, it can be released */
 211
 212         if (bitmap->bp[page].hijacked) { /* page was hijacked, undo this now */
 213                 bitmap->bp[page].hijacked = 0;
 214                 bitmap->bp[page].map = NULL;
 215                 return;
 216         }
 217
 218         /* normal case, free the page */
 219
 220 #if 0
 221 /* actually ... let's not.  We will probably need the page again exactly when
 222  * memory is tight and we are flusing to disk
 223  */
 224         return;
 225 #else
 226         ptr = bitmap->bp[page].map;
 227         bitmap->bp[page].map = NULL;
 228         bitmap->missing_pages++;
 229         bitmap_free_page(bitmap, ptr);
 230         return;
 231 #endif
 232 }
 233
 234
 235 /*
 236  * bitmap file handling - read and write the bitmap file and its superblock
 237  */
 238
 239 /* copy the pathname of a file to a buffer */
 240 char *file_path(struct file *file, char *buf, int count)
 241 {
 242         struct dentry *d;
 243         struct vfsmount *v;
 244
 245         if (!buf)
 246                 return NULL;
 247
 248         d = file->f_dentry;
 249         v = file->f_vfsmnt;
 250
 251         buf = d_path(d, v, buf, count);
 252
 253         return IS_ERR(buf) ? NULL : buf;
 254 }
 255
 256 /*
 257  * basic page I/O operations
 258  */
 259
 260 /* IO operations when bitmap is stored near all superblocks */
 261 static struct page *read_sb_page(mddev_t *mddev, long offset, unsigned long index)
 262 {
 263         /* choose a good rdev and read the page from there */
 264
 265         mdk_rdev_t *rdev;
 266         struct list_head *tmp;
 267         struct page *page = alloc_page(GFP_KERNEL);
 268         sector_t target;
 269
 270         if (!page)
 271                 return ERR_PTR(-ENOMEM);
 272
 273         ITERATE_RDEV(mddev, rdev, tmp) {
 274                 if (! test_bit(In_sync, &rdev->flags)
 275                     || test_bit(Faulty, &rdev->flags))
 276                         continue;
 277
 278                 target = (rdev->sb_offset << 1) + offset + index * (PAGE_SIZE/512);
 279
 280                 if (sync_page_io(rdev->bdev, target, PAGE_SIZE, page, READ)) {
 281                         page->index = index;
 282                         return page;
 283                 }
 284         }
 285         return ERR_PTR(-EIO);
 286
 287 }
 288
 289 static int write_sb_page(mddev_t *mddev, long offset, struct page *page, int wait)
 290 {
 291         mdk_rdev_t *rdev;
 292         struct list_head *tmp;
 293
 294         ITERATE_RDEV(mddev, rdev, tmp)
 295                 if (test_bit(In_sync, &rdev->flags)
 296                     && !test_bit(Faulty, &rdev->flags))
 297                         md_super_write(mddev, rdev,
 298                                        (rdev->sb_offset<<1) + offset
 299                                        + page->index * (PAGE_SIZE/512),
 300                                        PAGE_SIZE,
 301                                        page);
 302
 303         if (wait)
 304                 md_super_wait(mddev);
 305         return 0;
 306 }
 307
 308 /*
 309  * write out a page to a file
 310  */
 311 static int write_page(struct bitmap *bitmap, struct page *page, int wait)
 312 {
 313         int ret = -ENOMEM;
 314
 315         if (bitmap->file == NULL)
 316                 return write_sb_page(bitmap->mddev, bitmap->offset, page, wait);
 317
 318         flush_dcache_page(page); /* make sure visible to anyone reading the file */
 319
 320         if (wait)
 321                 lock_page(page);
 322         else {
 323                 if (TestSetPageLocked(page))
 324                         return -EAGAIN; /* already locked */
 325                 if (PageWriteback(page)) {
 326                         unlock_page(page);
 327                         return -EAGAIN;
 328                 }
 329         }
 330
 331         ret = page->mapping->a_ops->prepare_write(bitmap->file, page, 0, PAGE_SIZE);
 332         if (!ret)
 333                 ret = page->mapping->a_ops->commit_write(bitmap->file, page, 0,
 334                         PAGE_SIZE);
 335         if (ret) {
 336                 unlock_page(page);
 337                 return ret;
 338         }
 339
 340         set_page_dirty(page); /* force it to be written out */
 341
 342         if (!wait) {
 343                 /* add to list to be waited for by daemon */
 344                 struct page_list *item = mempool_alloc(bitmap->write_pool, GFP_NOIO);
 345                 item->page = page;
 346                 get_page(page);
 347                 spin_lock(&bitmap->write_lock);
 348                 list_add(&item->list, &bitmap->complete_pages);
 349                 spin_unlock(&bitmap->write_lock);
 350                 md_wakeup_thread(bitmap->writeback_daemon);
 351         }
 352         return write_one_page(page, wait);
 353 }
 354
 355 /* read a page from a file, pinning it into cache, and return bytes_read */
 356 static struct page *read_page(struct file *file, unsigned long index,
 357                                         unsigned long *bytes_read)
 358 {
 359         struct inode *inode = file->f_mapping->host;
 360         struct page *page = NULL;
 361         loff_t isize = i_size_read(inode);
 362         unsigned long end_index = isize >> PAGE_SHIFT;
 363
 364         PRINTK("read bitmap file (%dB @ %Lu)\n", (int)PAGE_SIZE,
 365                         (unsigned long long)index << PAGE_SHIFT);
 366
 367         page = read_cache_page(inode->i_mapping, index,
 368                         (filler_t *)inode->i_mapping->a_ops->readpage, file);
 369         if (IS_ERR(page))
 370                 goto out;
 371         wait_on_page_locked(page);
 372         if (!PageUptodate(page) || PageError(page)) {
 373                 put_page(page);
 374                 page = ERR_PTR(-EIO);
 375                 goto out;
 376         }
 377
 378         if (index > end_index) /* we have read beyond EOF */
 379                 *bytes_read = 0;
 380         else if (index == end_index) /* possible short read */
 381                 *bytes_read = isize & ~PAGE_MASK;
 382         else
 383                 *bytes_read = PAGE_SIZE; /* got a full page */
 384 out:
 385         if (IS_ERR(page))
 386                 printk(KERN_ALERT "md: bitmap read error: (%dB @ %Lu): %ld\n",
 387                         (int)PAGE_SIZE,
 388                         (unsigned long long)index << PAGE_SHIFT,
 389                         PTR_ERR(page));
 390         return page;
 391 }
 392
 393 /*
 394  * bitmap file superblock operations
 395  */
 396
 397 /* update the event counter and sync the superblock to disk */
 398 int bitmap_update_sb(struct bitmap *bitmap)
 399 {
 400         bitmap_super_t *sb;
 401         unsigned long flags;
 402
 403         if (!bitmap || !bitmap->mddev) /* no bitmap for this array */
 404                 return 0;
 405         spin_lock_irqsave(&bitmap->lock, flags);
 406         if (!bitmap->sb_page) { /* no superblock */
 407                 spin_unlock_irqrestore(&bitmap->lock, flags);
 408                 return 0;
 409         }
 410         spin_unlock_irqrestore(&bitmap->lock, flags);
 411         sb = (bitmap_super_t *)kmap_atomic(bitmap->sb_page, KM_USER0);
 412         sb->events = cpu_to_le64(bitmap->mddev->events);
 413         if (!bitmap->mddev->degraded)
 414                 sb->events_cleared = cpu_to_le64(bitmap->mddev->events);
 415         kunmap_atomic(sb, KM_USER0);
 416         return write_page(bitmap, bitmap->sb_page, 1);
 417 }
 418
 419 /* print out the bitmap file superblock */
 420 void bitmap_print_sb(struct bitmap *bitmap)
 421 {
 422         bitmap_super_t *sb;
 423
 424         if (!bitmap || !bitmap->sb_page)
 425                 return;
 426         sb = (bitmap_super_t *)kmap_atomic(bitmap->sb_page, KM_USER0);
 427         printk(KERN_DEBUG "%s: bitmap file superblock:\n", bmname(bitmap));
 428         printk(KERN_DEBUG "         magic: %08x\n", le32_to_cpu(sb->magic));
 429         printk(KERN_DEBUG "       version: %d\n", le32_to_cpu(sb->version));
 430         printk(KERN_DEBUG "          uuid: %08x.%08x.%08x.%08x\n",
 431                                         *(__u32 *)(sb->uuid+0),
 432                                         *(__u32 *)(sb->uuid+4),
 433                                         *(__u32 *)(sb->uuid+8),
 434                                         *(__u32 *)(sb->uuid+12));
 435         printk(KERN_DEBUG "        events: %llu\n",
 436                         (unsigned long long) le64_to_cpu(sb->events));
 437         printk(KERN_DEBUG "events cleared: %llu\n",
 438                         (unsigned long long) le64_to_cpu(sb->events_cleared));
 439         printk(KERN_DEBUG "         state: %08x\n", le32_to_cpu(sb->state));
 440         printk(KERN_DEBUG "     chunksize: %d B\n", le32_to_cpu(sb->chunksize));
 441         printk(KERN_DEBUG "  daemon sleep: %ds\n", le32_to_cpu(sb->daemon_sleep));
 442         printk(KERN_DEBUG "     sync size: %llu KB\n",
 443                         (unsigned long long)le64_to_cpu(sb->sync_size)/2);
 444         printk(KERN_DEBUG "max write behind: %d\n", le32_to_cpu(sb->write_behind));
 445         kunmap_atomic(sb, KM_USER0);
 446 }
 447
 448 /* read the superblock from the bitmap file and initialize some bitmap fields */
 449 static int bitmap_read_sb(struct bitmap *bitmap)
 450 {
 451         char *reason = NULL;
 452         bitmap_super_t *sb;
 453         unsigned long chunksize, daemon_sleep, write_behind;
 454         unsigned long bytes_read;
 455         unsigned long long events;
 456         int err = -EINVAL;
 457
 458         /* page 0 is the superblock, read it... */
 459         if (bitmap->file)
 460                 bitmap->sb_page = read_page(bitmap->file, 0, &bytes_read);
 461         else {
 462                 bitmap->sb_page = read_sb_page(bitmap->mddev, bitmap->offset, 0);
 463                 bytes_read = PAGE_SIZE;
 464         }
 465         if (IS_ERR(bitmap->sb_page)) {
 466                 err = PTR_ERR(bitmap->sb_page);
 467                 bitmap->sb_page = NULL;
 468                 return err;
 469         }
 470
 471         sb = (bitmap_super_t *)kmap_atomic(bitmap->sb_page, KM_USER0);
 472
 473         if (bytes_read < sizeof(*sb)) { /* short read */
 474                 printk(KERN_INFO "%s: bitmap file superblock truncated\n",
 475                         bmname(bitmap));
 476                 err = -ENOSPC;
 477                 goto out;
 478         }
 479
 480         chunksize = le32_to_cpu(sb->chunksize);
 481         daemon_sleep = le32_to_cpu(sb->daemon_sleep);
 482         write_behind = le32_to_cpu(sb->write_behind);
 483
 484         /* verify that the bitmap-specific fields are valid */
 485         if (sb->magic != cpu_to_le32(BITMAP_MAGIC))
 486                 reason = "bad magic";
 487         else if (le32_to_cpu(sb->version) < BITMAP_MAJOR_LO ||
 488                  le32_to_cpu(sb->version) > BITMAP_MAJOR_HI)
 489                 reason = "unrecognized superblock version";
 490         else if (chunksize < PAGE_SIZE)
 491                 reason = "bitmap chunksize too small";
 492         else if ((1 << ffz(~chunksize)) != chunksize)
 493                 reason = "bitmap chunksize not a power of 2";
 494         else if (daemon_sleep < 1 || daemon_sleep > MAX_SCHEDULE_TIMEOUT / HZ)
 495                 reason = "daemon sleep period out of range";
 496         else if (write_behind > COUNTER_MAX)
 497                 reason = "write-behind limit out of range (0 - 16383)";
 498         if (reason) {
 499                 printk(KERN_INFO "%s: invalid bitmap file superblock: %s\n",
 500                         bmname(bitmap), reason);
 501                 goto out;
 502         }
 503
 504         /* keep the array size field of the bitmap superblock up to date */
 505         sb->sync_size = cpu_to_le64(bitmap->mddev->resync_max_sectors);
 506
 507         if (!bitmap->mddev->persistent)
 508                 goto success;
 509
 510         /*
 511          * if we have a persistent array superblock, compare the
 512          * bitmap's UUID and event counter to the mddev's
 513          */
 514         if (memcmp(sb->uuid, bitmap->mddev->uuid, 16)) {
 515                 printk(KERN_INFO "%s: bitmap superblock UUID mismatch\n",
 516                         bmname(bitmap));
 517                 goto out;
 518         }
 519         events = le64_to_cpu(sb->events);
 520         if (events < bitmap->mddev->events) {
 521                 printk(KERN_INFO "%s: bitmap file is out of date (%llu < %llu) "
 522                         "-- forcing full recovery\n", bmname(bitmap), events,
 523                         (unsigned long long) bitmap->mddev->events);
 524                 sb->state |= BITMAP_STALE;
 525         }
 526 success:
 527         /* assign fields using values from superblock */
 528         bitmap->chunksize = chunksize;
 529         bitmap->daemon_sleep = daemon_sleep;
 530         bitmap->daemon_lastrun = jiffies;
 531         bitmap->max_write_behind = write_behind;
 532         bitmap->flags |= sb->state;
 533         if (le32_to_cpu(sb->version) == BITMAP_MAJOR_HOSTENDIAN)
 534                 bitmap->flags |= BITMAP_HOSTENDIAN;
 535         bitmap->events_cleared = le64_to_cpu(sb->events_cleared);
 536         if (sb->state & BITMAP_STALE)
 537                 bitmap->events_cleared = bitmap->mddev->events;
 538         err = 0;
 539 out:
 540         kunmap_atomic(sb, KM_USER0);
 541         if (err)
 542                 bitmap_print_sb(bitmap);
 543         return err;
 544 }
 545
 546 enum bitmap_mask_op {
 547         MASK_SET,
 548         MASK_UNSET
 549 };
 550
 551 /* record the state of the bitmap in the superblock */
 552 static void bitmap_mask_state(struct bitmap *bitmap, enum bitmap_state bits,
 553                                 enum bitmap_mask_op op)
 554 {
 555         bitmap_super_t *sb;
 556         unsigned long flags;
 557
 558         spin_lock_irqsave(&bitmap->lock, flags);
 559         if (!bitmap->sb_page) { /* can't set the state */
 560                 spin_unlock_irqrestore(&bitmap->lock, flags);
 561                 return;
 562         }
 563         get_page(bitmap->sb_page);
 564         spin_unlock_irqrestore(&bitmap->lock, flags);
 565         sb = (bitmap_super_t *)kmap_atomic(bitmap->sb_page, KM_USER0);
 566         switch (op) {
 567                 case MASK_SET: sb->state |= bits;
 568                                 break;
 569                 case MASK_UNSET: sb->state &= ~bits;
 570                                 break;
 571                 default: BUG();
 572         }
 573         kunmap_atomic(sb, KM_USER0);
 574         put_page(bitmap->sb_page);
 575 }
 576
 577 /*
 578  * general bitmap file operations
 579  */
 580
 581 /* calculate the index of the page that contains this bit */
 582 static inline unsigned long file_page_index(unsigned long chunk)
 583 {
 584         return CHUNK_BIT_OFFSET(chunk) >> PAGE_BIT_SHIFT;
 585 }
 586
 587 /* calculate the (bit) offset of this bit within a page */
 588 static inline unsigned long file_page_offset(unsigned long chunk)
 589 {
 590         return CHUNK_BIT_OFFSET(chunk) & (PAGE_BITS - 1);
 591 }
 592
 593 /*
 594  * return a pointer to the page in the filemap that contains the given bit
 595  *
 596  * this lookup is complicated by the fact that the bitmap sb might be exactly
 597  * 1 page (e.g., x86) or less than 1 page -- so the bitmap might start on page
 598  * 0 or page 1
 599  */
 600 static inline struct page *filemap_get_page(struct bitmap *bitmap,
 601                                         unsigned long chunk)
 602 {
 603         return bitmap->filemap[file_page_index(chunk) - file_page_index(0)];
 604 }
 605
 606
 607 static void bitmap_file_unmap(struct bitmap *bitmap)
 608 {
 609         struct page **map, *sb_page;
 610         unsigned long *attr;
 611         int pages;
 612         unsigned long flags;
 613
 614         spin_lock_irqsave(&bitmap->lock, flags);
 615         map = bitmap->filemap;
 616         bitmap->filemap = NULL;
 617         attr = bitmap->filemap_attr;
 618         bitmap->filemap_attr = NULL;
 619         pages = bitmap->file_pages;
 620         bitmap->file_pages = 0;
 621         sb_page = bitmap->sb_page;
 622         bitmap->sb_page = NULL;
 623         spin_unlock_irqrestore(&bitmap->lock, flags);
 624
 625         while (pages--)
 626                 if (map[pages]->index != 0) /* 0 is sb_page, release it below */
 627                         put_page(map[pages]);
 628         kfree(map);
 629         kfree(attr);
 630
 631         safe_put_page(sb_page);
 632 }
 633
 634 static void bitmap_stop_daemon(struct bitmap *bitmap);
 635
 636 /* dequeue the next item in a page list -- don't call from irq context */
 637 static struct page_list *dequeue_page(struct bitmap *bitmap)
 638 {
 639         struct page_list *item = NULL;
 640         struct list_head *head = &bitmap->complete_pages;
 641
 642         spin_lock(&bitmap->write_lock);
 643         if (list_empty(head))
 644                 goto out;
 645         item = list_entry(head->prev, struct page_list, list);
 646         list_del(head->prev);
 647 out:
 648         spin_unlock(&bitmap->write_lock);
 649         return item;
 650 }
 651
 652 static void drain_write_queues(struct bitmap *bitmap)
 653 {
 654         struct page_list *item;
 655
 656         while ((item = dequeue_page(bitmap))) {
 657                 /* don't bother to wait */
 658                 put_page(item->page);
 659                 mempool_free(item, bitmap->write_pool);
 660         }
 661
 662         wake_up(&bitmap->write_wait);
 663 }
 664
 665 static void bitmap_file_put(struct bitmap *bitmap)
 666 {
 667         struct file *file;
 668         struct inode *inode;
 669         unsigned long flags;
 670
 671         spin_lock_irqsave(&bitmap->lock, flags);
 672         file = bitmap->file;
 673         bitmap->file = NULL;
 674         spin_unlock_irqrestore(&bitmap->lock, flags);
 675
 676         bitmap_stop_daemon(bitmap);
 677
 678         drain_write_queues(bitmap);
 679
 680         bitmap_file_unmap(bitmap);
 681
 682         if (file) {
 683                 inode = file->f_mapping->host;
 684                 spin_lock(&inode->i_lock);
 685                 atomic_set(&inode->i_writecount, 1); /* allow writes again */
 686                 spin_unlock(&inode->i_lock);
 687                 fput(file);
 688         }
 689 }
 690
 691
 692 /*
 693  * bitmap_file_kick - if an error occurs while manipulating the bitmap file
 694  * then it is no longer reliable, so we stop using it and we mark the file
 695  * as failed in the superblock
 696  */
 697 static void bitmap_file_kick(struct bitmap *bitmap)
 698 {
 699         char *path, *ptr = NULL;
 700
 701         bitmap_mask_state(bitmap, BITMAP_STALE, MASK_SET);
 702         bitmap_update_sb(bitmap);
 703
 704         if (bitmap->file) {
 705                 path = kmalloc(PAGE_SIZE, GFP_KERNEL);
 706                 if (path)
 707                         ptr = file_path(bitmap->file, path, PAGE_SIZE);
 708
 709                 printk(KERN_ALERT "%s: kicking failed bitmap file %s from array!\n",
 710                        bmname(bitmap), ptr ? ptr : "");
 711
 712                 kfree(path);
 713         }
 714
 715         bitmap_file_put(bitmap);
 716
 717         return;
 718 }
 719
 720 enum bitmap_page_attr {
 721         BITMAP_PAGE_DIRTY = 1, // there are set bits that need to be synced
 722         BITMAP_PAGE_CLEAN = 2, // there are bits that might need to be cleared
 723         BITMAP_PAGE_NEEDWRITE=4, // there are cleared bits that need to be synced
 724 };
 725
 726 static inline void set_page_attr(struct bitmap *bitmap, struct page *page,
 727                                 enum bitmap_page_attr attr)
 728 {
 729         bitmap->filemap_attr[page->index] |= attr;
 730 }
 731
 732 static inline void clear_page_attr(struct bitmap *bitmap, struct page *page,
 733                                 enum bitmap_page_attr attr)
 734 {
 735         bitmap->filemap_attr[page->index] &= ~attr;
 736 }
 737
 738 static inline unsigned long get_page_attr(struct bitmap *bitmap, struct page *page)
 739 {
 740         return bitmap->filemap_attr[page->index];
 741 }
 742
 743 /*
 744  * bitmap_file_set_bit -- called before performing a write to the md device
 745  * to set (and eventually sync) a particular bit in the bitmap file
 746  *
 747  * we set the bit immediately, then we record the page number so that
 748  * when an unplug occurs, we can flush the dirty pages out to disk
 749  */
 750 static void bitmap_file_set_bit(struct bitmap *bitmap, sector_t block)
 751 {
 752         unsigned long bit;
 753         struct page *page;
 754         void *kaddr;
 755         unsigned long chunk = block >> CHUNK_BLOCK_SHIFT(bitmap);
 756
 757         if (!bitmap->filemap) {
 758                 return;
 759         }
 760
 761         page = filemap_get_page(bitmap, chunk);
 762         bit = file_page_offset(chunk);
 763
 764
 765         /* make sure the page stays cached until it gets written out */
 766         if (! (get_page_attr(bitmap, page) & BITMAP_PAGE_DIRTY))
 767                 get_page(page);
 768
 769         /* set the bit */
 770         kaddr = kmap_atomic(page, KM_USER0);
 771         if (bitmap->flags & BITMAP_HOSTENDIAN)
 772                 set_bit(bit, kaddr);
 773         else
 774                 ext2_set_bit(bit, kaddr);
 775         kunmap_atomic(kaddr, KM_USER0);
 776         PRINTK("set file bit %lu page %lu\n", bit, page->index);
 777
 778         /* record page number so it gets flushed to disk when unplug occurs */
 779         set_page_attr(bitmap, page, BITMAP_PAGE_DIRTY);
 780
 781 }
 782
 783 /* this gets called when the md device is ready to unplug its underlying
 784  * (slave) device queues -- before we let any writes go down, we need to
 785  * sync the dirty pages of the bitmap file to disk */
 786 int bitmap_unplug(struct bitmap *bitmap)
 787 {
 788         unsigned long i, attr, flags;
 789         struct page *page;
 790         int wait = 0;
 791         int err;
 792
 793         if (!bitmap)
 794                 return 0;
 795
 796         /* look at each page to see if there are any set bits that need to be
 797          * flushed out to disk */
 798         for (i = 0; i < bitmap->file_pages; i++) {
 799                 spin_lock_irqsave(&bitmap->lock, flags);
 800                 if (!bitmap->filemap) {
 801                         spin_unlock_irqrestore(&bitmap->lock, flags);
 802                         return 0;
 803                 }
 804                 page = bitmap->filemap[i];
 805                 attr = get_page_attr(bitmap, page);
 806                 clear_page_attr(bitmap, page, BITMAP_PAGE_DIRTY);
 807                 clear_page_attr(bitmap, page, BITMAP_PAGE_NEEDWRITE);
 808                 if ((attr & BITMAP_PAGE_DIRTY))
 809                         wait = 1;
 810                 spin_unlock_irqrestore(&bitmap->lock, flags);
 811
 812                 if (attr & (BITMAP_PAGE_DIRTY | BITMAP_PAGE_NEEDWRITE)) {
 813                         err = write_page(bitmap, page, 0);
 814                         if (err == -EAGAIN) {
 815                                 if (attr & BITMAP_PAGE_DIRTY)
 816                                         err = write_page(bitmap, page, 1);
 817                                 else
 818                                         err = 0;
 819                         }
 820                         if (err)
 821                                 return 1;
 822                 }
 823         }
 824         if (wait) { /* if any writes were performed, we need to wait on them */
 825                 if (bitmap->file) {
 826                         spin_lock_irq(&bitmap->write_lock);
 827                         wait_event_lock_irq(bitmap->write_wait,
 828                                             list_empty(&bitmap->complete_pages), bitmap->write_lock,
 829                                             wake_up_process(bitmap->writeback_daemon->tsk));
 830                         spin_unlock_irq(&bitmap->write_lock);
 831                 } else
 832                         md_super_wait(bitmap->mddev);
 833         }
 834         return 0;
 835 }
 836
 837 static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset, int needed);
 838 /* * bitmap_init_from_disk -- called at bitmap_create time to initialize
 839  * the in-memory bitmap from the on-disk bitmap -- also, sets up the
 840  * memory mapping of the bitmap file
 841  * Special cases:
 842  *   if there's no bitmap file, or if the bitmap file had been
 843  *   previously kicked from the array, we mark all the bits as
 844  *   1's in order to cause a full resync.
 845  *
 846  * We ignore all bits for sectors that end earlier than 'start'.
 847  * This is used when reading an out-of-date bitmap...
 848  */
 849 static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
 850 {
 851         unsigned long i, chunks, index, oldindex, bit;
 852         struct page *page = NULL, *oldpage = NULL;
 853         unsigned long num_pages, bit_cnt = 0;
 854         struct file *file;
 855         unsigned long bytes, offset, dummy;
 856         int outofdate;
 857         int ret = -ENOSPC;
 858         void *paddr;
 859
 860         chunks = bitmap->chunks;
 861         file = bitmap->file;
 862
 863         BUG_ON(!file && !bitmap->offset);
 864
 865 #ifdef INJECT_FAULTS_3
 866         outofdate = 1;
 867 #else
 868         outofdate = bitmap->flags & BITMAP_STALE;
 869 #endif
 870         if (outofdate)
 871                 printk(KERN_INFO "%s: bitmap file is out of date, doing full "
 872                         "recovery\n", bmname(bitmap));
 873
 874         bytes = (chunks + 7) / 8;
 875
 876         num_pages = (bytes + sizeof(bitmap_super_t) + PAGE_SIZE - 1) / PAGE_SIZE;
 877
 878         if (file && i_size_read(file->f_mapping->host) < bytes + sizeof(bitmap_super_t)) {
 879                 printk(KERN_INFO "%s: bitmap file too short %lu < %lu\n",
 880                         bmname(bitmap),
 881                         (unsigned long) i_size_read(file->f_mapping->host),
 882                         bytes + sizeof(bitmap_super_t));
 883                 goto out;
 884         }
 885
 886         ret = -ENOMEM;
 887
 888         bitmap->filemap = kmalloc(sizeof(struct page *) * num_pages, GFP_KERNEL);
 889         if (!bitmap->filemap)
 890                 goto out;
 891
 892         bitmap->filemap_attr = kzalloc(sizeof(long) * num_pages, GFP_KERNEL);
 893         if (!bitmap->filemap_attr)
 894                 goto out;
 895
 896         oldindex = ~0L;
 897
 898         for (i = 0; i < chunks; i++) {
 899                 int b;
 900                 index = file_page_index(i);
 901                 bit = file_page_offset(i);
 902                 if (index != oldindex) { /* this is a new page, read it in */
 903                         /* unmap the old page, we're done with it */
 904                         if (index == 0) {
 905                                 /*
 906                                  * if we're here then the superblock page
 907                                  * contains some bits (PAGE_SIZE != sizeof sb)
 908                                  * we've already read it in, so just use it
 909                                  */
 910                                 page = bitmap->sb_page;
 911                                 offset = sizeof(bitmap_super_t);
 912                         } else if (file) {
 913                                 page = read_page(file, index, &dummy);
 914                                 offset = 0;
 915                         } else {
 916                                 page = read_sb_page(bitmap->mddev, bitmap->offset, index);
 917                                 offset = 0;
 918                         }
 919                         if (IS_ERR(page)) { /* read error */
 920                                 ret = PTR_ERR(page);
 921                                 goto out;
 922                         }
 923
 924                         oldindex = index;
 925                         oldpage = page;
 926
 927                         if (outofdate) {
 928                                 /*
 929                                  * if bitmap is out of date, dirty the
 930                                  * whole page and write it out
 931                                  */
 932                                 paddr = kmap_atomic(page, KM_USER0);
 933                                 memset(paddr + offset, 0xff,
 934                                        PAGE_SIZE - offset);
 935                                 kunmap_atomic(paddr, KM_USER0);
 936                                 ret = write_page(bitmap, page, 1);
 937                                 if (ret) {
 938                                         /* release, page not in filemap yet */
 939                                         put_page(page);
 940                                         goto out;
 941                                 }
 942                         }
 943
 944                         bitmap->filemap[bitmap->file_pages++] = page;
 945                 }
 946                 paddr = kmap_atomic(page, KM_USER0);
 947                 if (bitmap->flags & BITMAP_HOSTENDIAN)
 948                         b = test_bit(bit, paddr);
 949                 else
 950                         b = ext2_test_bit(bit, paddr);
 951                 kunmap_atomic(paddr, KM_USER0);
 952                 if (b) {
 953                         /* if the disk bit is set, set the memory bit */
 954                         bitmap_set_memory_bits(bitmap, i << CHUNK_BLOCK_SHIFT(bitmap),
 955                                                ((i+1) << (CHUNK_BLOCK_SHIFT(bitmap)) >= start)
 956                                 );
 957                         bit_cnt++;
 958                         set_page_attr(bitmap, page, BITMAP_PAGE_CLEAN);
 959                 }
 960         }
 961
 962         /* everything went OK */
 963         ret = 0;
 964         bitmap_mask_state(bitmap, BITMAP_STALE, MASK_UNSET);
 965
 966         if (bit_cnt) { /* Kick recovery if any bits were set */
 967                 set_bit(MD_RECOVERY_NEEDED, &bitmap->mddev->recovery);
 968                 md_wakeup_thread(bitmap->mddev->thread);
 969         }
 970
 971 out:
 972         printk(KERN_INFO "%s: bitmap initialized from disk: "
 973                 "read %lu/%lu pages, set %lu bits, status: %d\n",
 974                 bmname(bitmap), bitmap->file_pages, num_pages, bit_cnt, ret);
 975
 976         return ret;
 977 }
 978
 979 void bitmap_write_all(struct bitmap *bitmap)
 980 {
 981         /* We don't actually write all bitmap blocks here,
 982          * just flag them as needing to be written
 983          */
 984
 985         unsigned long chunks = bitmap->chunks;
 986         unsigned long bytes = (chunks+7)/8 + sizeof(bitmap_super_t);
 987         unsigned long num_pages = (bytes + PAGE_SIZE-1) / PAGE_SIZE;
 988         while (num_pages--)
 989                 bitmap->filemap_attr[num_pages] |= BITMAP_PAGE_NEEDWRITE;
 990 }
 991
 992
 993 static void bitmap_count_page(struct bitmap *bitmap, sector_t offset, int inc)
 994 {
 995         sector_t chunk = offset >> CHUNK_BLOCK_SHIFT(bitmap);
 996         unsigned long page = chunk >> PAGE_COUNTER_SHIFT;
 997         bitmap->bp[page].count += inc;
 998 /*
 999         if (page == 0) printk("count page 0, offset %llu: %d gives %d\n",
1000                               (unsigned long long)offset, inc, bitmap->bp[page].count);
1001 */
1002         bitmap_checkfree(bitmap, page);
1003 }
1004 static bitmap_counter_t *bitmap_get_counter(struct bitmap *bitmap,
1005                                             sector_t offset, int *blocks,
1006                                             int create);
1007
1008 /*
1009  * bitmap daemon -- periodically wakes up to clean bits and flush pages
1010  *                      out to disk
1011  */
1012
1013 int bitmap_daemon_work(struct bitmap *bitmap)
1014 {
1015         unsigned long j;
1016         unsigned long flags;
1017         struct page *page = NULL, *lastpage = NULL;
1018         int err = 0;
1019         int blocks;
1020         int attr;
1021         void *paddr;
1022
1023         if (bitmap == NULL)
1024                 return 0;
1025         if (time_before(jiffies, bitmap->daemon_lastrun + bitmap->daemon_sleep*HZ))
1026                 return 0;
1027         bitmap->daemon_lastrun = jiffies;
1028
1029         for (j = 0; j < bitmap->chunks; j++) {
1030                 bitmap_counter_t *bmc;
1031                 spin_lock_irqsave(&bitmap->lock, flags);
1032                 if (!bitmap->filemap) {
1033                         /* error or shutdown */
1034                         spin_unlock_irqrestore(&bitmap->lock, flags);
1035                         break;
1036                 }
1037
1038                 page = filemap_get_page(bitmap, j);
1039
1040                 if (page != lastpage) {
1041                         /* skip this page unless it's marked as needing cleaning */
1042                         if (!((attr=get_page_attr(bitmap, page)) & BITMAP_PAGE_CLEAN)) {
1043                                 if (attr & BITMAP_PAGE_NEEDWRITE) {
1044                                         get_page(page);
1045                                         clear_page_attr(bitmap, page, BITMAP_PAGE_NEEDWRITE);
1046                                 }
1047                                 spin_unlock_irqrestore(&bitmap->lock, flags);
1048                                 if (attr & BITMAP_PAGE_NEEDWRITE) {
1049                                         switch (write_page(bitmap, page, 0)) {
1050                                         case -EAGAIN:
1051                                                 set_page_attr(bitmap, page, BITMAP_PAGE_NEEDWRITE);
1052                                                 break;
1053                                         case 0:
1054                                                 break;
1055                                         default:
1056                                                 bitmap_file_kick(bitmap);
1057                                         }
1058                                         put_page(page);
1059                                 }
1060                                 continue;
1061                         }
1062
1063                         /* grab the new page, sync and release the old */
1064                         get_page(page);
1065                         if (lastpage != NULL) {
1066                                 if (get_page_attr(bitmap, lastpage) & BITMAP_PAGE_NEEDWRITE) {
1067                                         clear_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
1068                                         spin_unlock_irqrestore(&bitmap->lock, flags);
1069                                         err = write_page(bitmap, lastpage, 0);
1070                                         if (err == -EAGAIN) {
1071                                                 err = 0;
1072                                                 set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
1073                                         }
1074                                 } else {
1075                                         set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
1076                                         spin_unlock_irqrestore(&bitmap->lock, flags);
1077                                 }
1078                                 put_page(lastpage);
1079                                 if (err)
1080                                         bitmap_file_kick(bitmap);
1081                         } else
1082                                 spin_unlock_irqrestore(&bitmap->lock, flags);
1083                         lastpage = page;
1084 /*
1085                         printk("bitmap clean at page %lu\n", j);
1086 */
1087                         spin_lock_irqsave(&bitmap->lock, flags);
1088                         clear_page_attr(bitmap, page, BITMAP_PAGE_CLEAN);
1089                 }
1090                 bmc = bitmap_get_counter(bitmap, j << CHUNK_BLOCK_SHIFT(bitmap),
1091                                         &blocks, 0);
1092                 if (bmc) {
1093 /*
1094   if (j < 100) printk("bitmap: j=%lu, *bmc = 0x%x\n", j, *bmc);
1095 */
1096                         if (*bmc == 2) {
1097                                 *bmc=1; /* maybe clear the bit next time */
1098                                 set_page_attr(bitmap, page, BITMAP_PAGE_CLEAN);
1099                         } else if (*bmc == 1) {
1100                                 /* we can clear the bit */
1101                                 *bmc = 0;
1102                                 bitmap_count_page(bitmap, j << CHUNK_BLOCK_SHIFT(bitmap),
1103                                                   -1);
1104
1105                                 /* clear the bit */
1106                                 paddr = kmap_atomic(page, KM_USER0);
1107                                 if (bitmap->flags & BITMAP_HOSTENDIAN)
1108                                         clear_bit(file_page_offset(j), paddr);
1109                                 else
1110                                         ext2_clear_bit(file_page_offset(j), paddr);
1111                                 kunmap_atomic(paddr, KM_USER0);
1112                         }
1113                 }
1114                 spin_unlock_irqrestore(&bitmap->lock, flags);
1115         }
1116
1117         /* now sync the final page */
1118         if (lastpage != NULL) {
1119                 spin_lock_irqsave(&bitmap->lock, flags);
1120                 if (get_page_attr(bitmap, lastpage) &BITMAP_PAGE_NEEDWRITE) {
1121                         clear_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
1122                         spin_unlock_irqrestore(&bitmap->lock, flags);
1123                         err = write_page(bitmap, lastpage, 0);
1124                         if (err == -EAGAIN) {
1125                                 set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
1126                                 err = 0;
1127                         }
1128                 } else {
1129                         set_page_attr(bitmap, lastpage, BITMAP_PAGE_NEEDWRITE);
1130                         spin_unlock_irqrestore(&bitmap->lock, flags);
1131                 }
1132
1133                 put_page(lastpage);
1134         }
1135
1136         return err;
1137 }
1138
1139 static void daemon_exit(struct bitmap *bitmap, mdk_thread_t **daemon)
1140 {
1141         mdk_thread_t *dmn;
1142         unsigned long flags;
1143
1144         /* if no one is waiting on us, we'll free the md thread struct
1145          * and exit, otherwise we let the waiter clean things up */
1146         spin_lock_irqsave(&bitmap->lock, flags);
1147         if ((dmn = *daemon)) { /* no one is waiting, cleanup and exit */
1148                 *daemon = NULL;
1149                 spin_unlock_irqrestore(&bitmap->lock, flags);
1150                 kfree(dmn);
1151                 complete_and_exit(NULL, 0); /* do_exit not exported */
1152         }
1153         spin_unlock_irqrestore(&bitmap->lock, flags);
1154 }
1155
1156 static void bitmap_writeback_daemon(mddev_t *mddev)
1157 {
1158         struct bitmap *bitmap = mddev->bitmap;
1159         struct page *page;
1160         struct page_list *item;
1161         int err = 0;
1162
1163         if (signal_pending(current)) {
1164                 printk(KERN_INFO
1165                        "%s: bitmap writeback daemon got signal, exiting...\n",
1166                        bmname(bitmap));
1167                 err = -EINTR;
1168                 goto out;
1169         }
1170         if (bitmap == NULL)
1171                 /* about to be stopped. */
1172                 return;
1173
1174         PRINTK("%s: bitmap writeback daemon woke up...\n", bmname(bitmap));
1175         /* wait on bitmap page writebacks */
1176         while ((item = dequeue_page(bitmap))) {
1177                 page = item->page;
1178                 mempool_free(item, bitmap->write_pool);
1179                 PRINTK("wait on page writeback: %p\n", page);
1180                 wait_on_page_writeback(page);
1181                 PRINTK("finished page writeback: %p\n", page);
1182
1183                 err = PageError(page);
1184                 put_page(page);
1185                 if (err) {
1186                         printk(KERN_WARNING "%s: bitmap file writeback "
1187                                "failed (page %lu): %d\n",
1188                                bmname(bitmap), page->index, err);
1189                         bitmap_file_kick(bitmap);
1190                         goto out;
1191                 }
1192         }
1193  out:
1194         wake_up(&bitmap->write_wait);
1195         if (err) {
1196                 printk(KERN_INFO "%s: bitmap writeback daemon exiting (%d)\n",
1197                        bmname(bitmap), err);
1198                 daemon_exit(bitmap, &bitmap->writeback_daemon);
1199         }
1200 }
1201
1202 static mdk_thread_t *bitmap_start_daemon(struct bitmap *bitmap,
1203                                 void (*func)(mddev_t *), char *name)
1204 {
1205         mdk_thread_t *daemon;
1206         char namebuf[32];
1207
1208 #ifdef INJECT_FATAL_FAULT_2
1209         daemon = NULL;
1210 #else
1211         sprintf(namebuf, "%%s_%s", name);
1212         daemon = md_register_thread(func, bitmap->mddev, namebuf);
1213 #endif
1214         if (!daemon) {
1215                 printk(KERN_ERR "%s: failed to start bitmap daemon\n",
1216                         bmname(bitmap));
1217                 return ERR_PTR(-ECHILD);
1218         }
1219
1220         md_wakeup_thread(daemon); /* start it running */
1221
1222         PRINTK("%s: %s daemon (pid %d) started...\n",
1223                 bmname(bitmap), name, daemon->tsk->pid);
1224
1225         return daemon;
1226 }
1227
1228 static void bitmap_stop_daemon(struct bitmap *bitmap)
1229 {
1230         /* the daemon can't stop itself... it'll just exit instead... */
1231         if (bitmap->writeback_daemon && ! IS_ERR(bitmap->writeback_daemon) &&
1232             current->pid != bitmap->writeback_daemon->tsk->pid) {
1233                 mdk_thread_t *daemon;
1234                 unsigned long flags;
1235
1236                 spin_lock_irqsave(&bitmap->lock, flags);
1237                 daemon = bitmap->writeback_daemon;
1238                 bitmap->writeback_daemon = NULL;
1239                 spin_unlock_irqrestore(&bitmap->lock, flags);
1240                 if (daemon && ! IS_ERR(daemon))
1241                         md_unregister_thread(daemon); /* destroy the thread */
1242         }
1243 }
1244
1245 static bitmap_counter_t *bitmap_get_counter(struct bitmap *bitmap,
1246                                             sector_t offset, int *blocks,
1247                                             int create)
1248 {
1249         /* If 'create', we might release the lock and reclaim it.
1250          * The lock must have been taken with interrupts enabled.
1251          * If !create, we don't release the lock.
1252          */
1253         sector_t chunk = offset >> CHUNK_BLOCK_SHIFT(bitmap);
1254         unsigned long page = chunk >> PAGE_COUNTER_SHIFT;
1255         unsigned long pageoff = (chunk & PAGE_COUNTER_MASK) << COUNTER_BYTE_SHIFT;
1256         sector_t csize;
1257
1258         if (bitmap_checkpage(bitmap, page, create) < 0) {
1259                 csize = ((sector_t)1) << (CHUNK_BLOCK_SHIFT(bitmap));
1260                 *blocks = csize - (offset & (csize- 1));
1261                 return NULL;
1262         }
1263         /* now locked ... */
1264
1265         if (bitmap->bp[page].hijacked) { /* hijacked pointer */
1266                 /* should we use the first or second counter field
1267                  * of the hijacked pointer? */
1268                 int hi = (pageoff > PAGE_COUNTER_MASK);
1269                 csize = ((sector_t)1) << (CHUNK_BLOCK_SHIFT(bitmap) +
1270                                           PAGE_COUNTER_SHIFT - 1);
1271                 *blocks = csize - (offset & (csize- 1));
1272                 return  &((bitmap_counter_t *)
1273                           &bitmap->bp[page].map)[hi];
1274         } else { /* page is allocated */
1275                 csize = ((sector_t)1) << (CHUNK_BLOCK_SHIFT(bitmap));
1276                 *blocks = csize - (offset & (csize- 1));
1277                 return (bitmap_counter_t *)
1278                         &(bitmap->bp[page].map[pageoff]);
1279         }
1280 }
1281
1282 int bitmap_startwrite(struct bitmap *bitmap, sector_t offset, unsigned long sectors, int behind)
1283 {
1284         if (!bitmap) return 0;
1285
1286         if (behind) {
1287                 atomic_inc(&bitmap->behind_writes);
1288                 PRINTK(KERN_DEBUG "inc write-behind count %d/%d\n",
1289                   atomic_read(&bitmap->behind_writes), bitmap->max_write_behind);
1290         }
1291
1292         while (sectors) {
1293                 int blocks;
1294                 bitmap_counter_t *bmc;
1295
1296                 spin_lock_irq(&bitmap->lock);
1297                 bmc = bitmap_get_counter(bitmap, offset, &blocks, 1);
1298                 if (!bmc) {
1299                         spin_unlock_irq(&bitmap->lock);
1300                         return 0;
1301                 }
1302
1303                 switch(*bmc) {
1304                 case 0:
1305                         bitmap_file_set_bit(bitmap, offset);
1306                         bitmap_count_page(bitmap,offset, 1);
1307                         blk_plug_device(bitmap->mddev->queue);
1308                         /* fall through */
1309                 case 1:
1310                         *bmc = 2;
1311                 }
1312                 if ((*bmc & COUNTER_MAX) == COUNTER_MAX) BUG();
1313                 (*bmc)++;
1314
1315                 spin_unlock_irq(&bitmap->lock);
1316
1317                 offset += blocks;
1318                 if (sectors > blocks)
1319                         sectors -= blocks;
1320                 else sectors = 0;
1321         }
1322         return 0;
1323 }
1324
1325 void bitmap_endwrite(struct bitmap *bitmap, sector_t offset, unsigned long sectors,
1326                      int success, int behind)
1327 {
1328         if (!bitmap) return;
1329         if (behind) {
1330                 atomic_dec(&bitmap->behind_writes);
1331                 PRINTK(KERN_DEBUG "dec write-behind count %d/%d\n",
1332                   atomic_read(&bitmap->behind_writes), bitmap->max_write_behind);
1333         }
1334
1335         while (sectors) {
1336                 int blocks;
1337                 unsigned long flags;
1338                 bitmap_counter_t *bmc;
1339
1340                 spin_lock_irqsave(&bitmap->lock, flags);
1341                 bmc = bitmap_get_counter(bitmap, offset, &blocks, 0);
1342                 if (!bmc) {
1343                         spin_unlock_irqrestore(&bitmap->lock, flags);
1344                         return;
1345                 }
1346
1347                 if (!success && ! (*bmc & NEEDED_MASK))
1348                         *bmc |= NEEDED_MASK;
1349
1350                 (*bmc)--;
1351                 if (*bmc <= 2) {
1352                         set_page_attr(bitmap,
1353                                       filemap_get_page(bitmap, offset >> CHUNK_BLOCK_SHIFT(bitmap)),
1354                                       BITMAP_PAGE_CLEAN);
1355                 }
1356                 spin_unlock_irqrestore(&bitmap->lock, flags);
1357                 offset += blocks;
1358                 if (sectors > blocks)
1359                         sectors -= blocks;
1360                 else sectors = 0;
1361         }
1362 }
1363
1364 int bitmap_start_sync(struct bitmap *bitmap, sector_t offset, int *blocks,
1365                         int degraded)
1366 {
1367         bitmap_counter_t *bmc;
1368         int rv;
1369         if (bitmap == NULL) {/* FIXME or bitmap set as 'failed' */
1370                 *blocks = 1024;
1371                 return 1; /* always resync if no bitmap */
1372         }
1373         spin_lock_irq(&bitmap->lock);
1374         bmc = bitmap_get_counter(bitmap, offset, blocks, 0);
1375         rv = 0;
1376         if (bmc) {
1377                 /* locked */
1378                 if (RESYNC(*bmc))
1379                         rv = 1;
1380                 else if (NEEDED(*bmc)) {
1381                         rv = 1;
1382                         if (!degraded) { /* don't set/clear bits if degraded */
1383                                 *bmc |= RESYNC_MASK;
1384                                 *bmc &= ~NEEDED_MASK;
1385                         }
1386                 }
1387         }
1388         spin_unlock_irq(&bitmap->lock);
1389         return rv;
1390 }
1391
1392 void bitmap_end_sync(struct bitmap *bitmap, sector_t offset, int *blocks, int aborted)
1393 {
1394         bitmap_counter_t *bmc;
1395         unsigned long flags;
1396 /*
1397         if (offset == 0) printk("bitmap_end_sync 0 (%d)\n", aborted);
1398 */      if (bitmap == NULL) {
1399                 *blocks = 1024;
1400                 return;
1401         }
1402         spin_lock_irqsave(&bitmap->lock, flags);
1403         bmc = bitmap_get_counter(bitmap, offset, blocks, 0);
1404         if (bmc == NULL)
1405                 goto unlock;
1406         /* locked */
1407 /*
1408         if (offset == 0) printk("bitmap_end sync found 0x%x, blocks %d\n", *bmc, *blocks);
1409 */
1410         if (RESYNC(*bmc)) {
1411                 *bmc &= ~RESYNC_MASK;
1412
1413                 if (!NEEDED(*bmc) && aborted)
1414                         *bmc |= NEEDED_MASK;
1415                 else {
1416                         if (*bmc <= 2) {
1417                                 set_page_attr(bitmap,
1418                                               filemap_get_page(bitmap, offset >> CHUNK_BLOCK_SHIFT(bitmap)),
1419                                               BITMAP_PAGE_CLEAN);
1420                         }
1421                 }
1422         }
1423  unlock:
1424         spin_unlock_irqrestore(&bitmap->lock, flags);
1425 }
1426
1427 void bitmap_close_sync(struct bitmap *bitmap)
1428 {
1429         /* Sync has finished, and any bitmap chunks that weren't synced
1430          * properly have been aborted.  It remains to us to clear the
1431          * RESYNC bit wherever it is still on
1432          */
1433         sector_t sector = 0;
1434         int blocks;
1435         if (!bitmap) return;
1436         while (sector < bitmap->mddev->resync_max_sectors) {
1437                 bitmap_end_sync(bitmap, sector, &blocks, 0);
1438 /*
1439                 if (sector < 500) printk("bitmap_close_sync: sec %llu blks %d\n",
1440                                          (unsigned long long)sector, blocks);
1441 */              sector += blocks;
1442         }
1443 }
1444
1445 static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset, int needed)
1446 {
1447         /* For each chunk covered by any of these sectors, set the
1448          * counter to 1 and set resync_needed.  They should all
1449          * be 0 at this point
1450          */
1451
1452         int secs;
1453         bitmap_counter_t *bmc;
1454         spin_lock_irq(&bitmap->lock);
1455         bmc = bitmap_get_counter(bitmap, offset, &secs, 1);
1456         if (!bmc) {
1457                 spin_unlock_irq(&bitmap->lock);
1458                 return;
1459         }
1460         if (! *bmc) {
1461                 struct page *page;
1462                 *bmc = 1 | (needed?NEEDED_MASK:0);
1463                 bitmap_count_page(bitmap, offset, 1);
1464                 page = filemap_get_page(bitmap, offset >> CHUNK_BLOCK_SHIFT(bitmap));
1465                 set_page_attr(bitmap, page, BITMAP_PAGE_CLEAN);
1466         }
1467         spin_unlock_irq(&bitmap->lock);
1468
1469 }
1470
1471 /*
1472  * flush out any pending updates
1473  */
1474 void bitmap_flush(mddev_t *mddev)
1475 {
1476         struct bitmap *bitmap = mddev->bitmap;
1477         int sleep;
1478
1479         if (!bitmap) /* there was no bitmap */
1480                 return;
1481
1482         /* run the daemon_work three time to ensure everything is flushed
1483          * that can be
1484          */
1485         sleep = bitmap->daemon_sleep;
1486         bitmap->daemon_sleep = 0;
1487         bitmap_daemon_work(bitmap);
1488         bitmap_daemon_work(bitmap);
1489         bitmap_daemon_work(bitmap);
1490         bitmap->daemon_sleep = sleep;
1491         bitmap_update_sb(bitmap);
1492 }
1493
1494 /*
1495  * free memory that was allocated
1496  */
1497 static void bitmap_free(struct bitmap *bitmap)
1498 {
1499         unsigned long k, pages;
1500         struct bitmap_page *bp;
1501
1502         if (!bitmap) /* there was no bitmap */
1503                 return;
1504
1505         /* release the bitmap file and kill the daemon */
1506         bitmap_file_put(bitmap);
1507
1508         bp = bitmap->bp;
1509         pages = bitmap->pages;
1510
1511         /* free all allocated memory */
1512
1513         mempool_destroy(bitmap->write_pool);
1514
1515         if (bp) /* deallocate the page memory */
1516                 for (k = 0; k < pages; k++)
1517                         if (bp[k].map && !bp[k].hijacked)
1518                                 kfree(bp[k].map);
1519         kfree(bp);
1520         kfree(bitmap);
1521 }
1522 void bitmap_destroy(mddev_t *mddev)
1523 {
1524         struct bitmap *bitmap = mddev->bitmap;
1525
1526         if (!bitmap) /* there was no bitmap */
1527                 return;
1528
1529         mddev->bitmap = NULL; /* disconnect from the md device */
1530         if (mddev->thread)
1531                 mddev->thread->timeout = MAX_SCHEDULE_TIMEOUT;
1532
1533         bitmap_free(bitmap);
1534 }
1535
1536 /*
1537  * initialize the bitmap structure
1538  * if this returns an error, bitmap_destroy must be called to do clean up
1539  */
1540 int bitmap_create(mddev_t *mddev)
1541 {
1542         struct bitmap *bitmap;
1543         unsigned long blocks = mddev->resync_max_sectors;
1544         unsigned long chunks;
1545         unsigned long pages;
1546         struct file *file = mddev->bitmap_file;
1547         int err;
1548         sector_t start;
1549
1550         BUG_ON(sizeof(bitmap_super_t) != 256);
1551
1552         if (!file && !mddev->bitmap_offset) /* bitmap disabled, nothing to do */
1553                 return 0;
1554
1555         BUG_ON(file && mddev->bitmap_offset);
1556
1557         bitmap = kzalloc(sizeof(*bitmap), GFP_KERNEL);
1558         if (!bitmap)
1559                 return -ENOMEM;
1560
1561         spin_lock_init(&bitmap->lock);
1562         bitmap->mddev = mddev;
1563
1564         spin_lock_init(&bitmap->write_lock);
1565         INIT_LIST_HEAD(&bitmap->complete_pages);
1566         init_waitqueue_head(&bitmap->write_wait);
1567         bitmap->write_pool = mempool_create(WRITE_POOL_SIZE, write_pool_alloc,
1568                                 write_pool_free, NULL);
1569         err = -ENOMEM;
1570         if (!bitmap->write_pool)
1571                 goto error;
1572
1573         bitmap->file = file;
1574         bitmap->offset = mddev->bitmap_offset;
1575         if (file) get_file(file);
1576         /* read superblock from bitmap file (this sets bitmap->chunksize) */
1577         err = bitmap_read_sb(bitmap);
1578         if (err)
1579                 goto error;
1580
1581         bitmap->chunkshift = find_first_bit(&bitmap->chunksize,
1582                                         sizeof(bitmap->chunksize));
1583
1584         /* now that chunksize and chunkshift are set, we can use these macros */
1585         chunks = (blocks + CHUNK_BLOCK_RATIO(bitmap) - 1) /
1586                         CHUNK_BLOCK_RATIO(bitmap);
1587         pages = (chunks + PAGE_COUNTER_RATIO - 1) / PAGE_COUNTER_RATIO;
1588
1589         BUG_ON(!pages);
1590
1591         bitmap->chunks = chunks;
1592         bitmap->pages = pages;
1593         bitmap->missing_pages = pages;
1594         bitmap->counter_bits = COUNTER_BITS;
1595
1596         bitmap->syncchunk = ~0UL;
1597
1598 #ifdef INJECT_FATAL_FAULT_1
1599         bitmap->bp = NULL;
1600 #else
1601         bitmap->bp = kzalloc(pages * sizeof(*bitmap->bp), GFP_KERNEL);
1602 #endif
1603         err = -ENOMEM;
1604         if (!bitmap->bp)
1605                 goto error;
1606
1607         bitmap->flags |= BITMAP_ACTIVE;
1608
1609         /* now that we have some pages available, initialize the in-memory
1610          * bitmap from the on-disk bitmap */
1611         start = 0;
1612         if (mddev->degraded == 0
1613             || bitmap->events_cleared == mddev->events)
1614                 /* no need to keep dirty bits to optimise a re-add of a missing device */
1615                 start = mddev->recovery_cp;
1616         err = bitmap_init_from_disk(bitmap, start);
1617
1618         if (err)
1619                 goto error;
1620
1621         printk(KERN_INFO "created bitmap (%lu pages) for device %s\n",
1622                 pages, bmname(bitmap));
1623
1624         mddev->bitmap = bitmap;
1625
1626         if (file)
1627                 /* kick off the bitmap writeback daemon */
1628                 bitmap->writeback_daemon =
1629                         bitmap_start_daemon(bitmap,
1630                                             bitmap_writeback_daemon,
1631                                             "bitmap_wb");
1632
1633         if (IS_ERR(bitmap->writeback_daemon))
1634                 return PTR_ERR(bitmap->writeback_daemon);
1635         mddev->thread->timeout = bitmap->daemon_sleep * HZ;
1636
1637         return bitmap_update_sb(bitmap);
1638
1639  error:
1640         bitmap_free(bitmap);
1641         return err;
1642 }
1643
1644 /* the bitmap API -- for raid personalities */
1645 EXPORT_SYMBOL(bitmap_startwrite);
1646 EXPORT_SYMBOL(bitmap_endwrite);
1647 EXPORT_SYMBOL(bitmap_start_sync);
1648 EXPORT_SYMBOL(bitmap_end_sync);
1649 EXPORT_SYMBOL(bitmap_unplug);
1650 EXPORT_SYMBOL(bitmap_close_sync);
1651 EXPORT_SYMBOL(bitmap_daemon_work);