linux/drivers/md/bitmap.c
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   1/*
   2 * bitmap.c two-level bitmap (C) Peter T. Breuer (ptb@ot.uc3m.es) 2003
   3 *
   4 * bitmap_create  - sets up the bitmap structure
   5 * bitmap_destroy - destroys the bitmap structure
   6 *
   7 * additions, Copyright (C) 2003-2004, Paul Clements, SteelEye Technology, Inc.:
   8 * - added disk storage for bitmap
   9 * - changes to allow various bitmap chunk sizes
  10 */
  11
  12/*
  13 * Still to do:
  14 *
  15 * flush after percent set rather than just time based. (maybe both).
  16 */
  17
  18#include <linux/blkdev.h>
  19#include <linux/module.h>
  20#include <linux/errno.h>
  21#include <linux/slab.h>
  22#include <linux/init.h>
  23#include <linux/timer.h>
  24#include <linux/sched.h>
  25#include <linux/list.h>
  26#include <linux/file.h>
  27#include <linux/mount.h>
  28#include <linux/buffer_head.h>
  29#include <linux/seq_file.h>
  30#include "md.h"
  31#include "bitmap.h"
  32
  33static inline char *bmname(struct bitmap *bitmap)
  34{
  35        return bitmap->mddev ? mdname(bitmap->mddev) : "mdX";
  36}
  37
  38/*
  39 * check a page and, if necessary, allocate it (or hijack it if the alloc fails)
  40 *
  41 * 1) check to see if this page is allocated, if it's not then try to alloc
  42 * 2) if the alloc fails, set the page's hijacked flag so we'll use the
  43 *    page pointer directly as a counter
  44 *
  45 * if we find our page, we increment the page's refcount so that it stays
  46 * allocated while we're using it
  47 */
  48static int bitmap_checkpage(struct bitmap_counts *bitmap,
  49                            unsigned long page, int create)
  50__releases(bitmap->lock)
  51__acquires(bitmap->lock)
  52{
  53        unsigned char *mappage;
  54
  55        if (page >= bitmap->pages) {
  56                /* This can happen if bitmap_start_sync goes beyond
  57                 * End-of-device while looking for a whole page.
  58                 * It is harmless.
  59                 */
  60                return -EINVAL;
  61        }
  62
  63        if (bitmap->bp[page].hijacked) /* it's hijacked, don't try to alloc */
  64                return 0;
  65
  66        if (bitmap->bp[page].map) /* page is already allocated, just return */
  67                return 0;
  68
  69        if (!create)
  70                return -ENOENT;
  71
  72        /* this page has not been allocated yet */
  73
  74        spin_unlock_irq(&bitmap->lock);
  75        mappage = kzalloc(PAGE_SIZE, GFP_NOIO);
  76        spin_lock_irq(&bitmap->lock);
  77
  78        if (mappage == NULL) {
  79                pr_debug("md/bitmap: map page allocation failed, hijacking\n");
  80                /* failed - set the hijacked flag so that we can use the
  81                 * pointer as a counter */
  82                if (!bitmap->bp[page].map)
  83                        bitmap->bp[page].hijacked = 1;
  84        } else if (bitmap->bp[page].map ||
  85                   bitmap->bp[page].hijacked) {
  86                /* somebody beat us to getting the page */
  87                kfree(mappage);
  88                return 0;
  89        } else {
  90
  91                /* no page was in place and we have one, so install it */
  92
  93                bitmap->bp[page].map = mappage;
  94                bitmap->missing_pages--;
  95        }
  96        return 0;
  97}
  98
  99/* if page is completely empty, put it back on the free list, or dealloc it */
 100/* if page was hijacked, unmark the flag so it might get alloced next time */
 101/* Note: lock should be held when calling this */
 102static void bitmap_checkfree(struct bitmap_counts *bitmap, unsigned long page)
 103{
 104        char *ptr;
 105
 106        if (bitmap->bp[page].count) /* page is still busy */
 107                return;
 108
 109        /* page is no longer in use, it can be released */
 110
 111        if (bitmap->bp[page].hijacked) { /* page was hijacked, undo this now */
 112                bitmap->bp[page].hijacked = 0;
 113                bitmap->bp[page].map = NULL;
 114        } else {
 115                /* normal case, free the page */
 116                ptr = bitmap->bp[page].map;
 117                bitmap->bp[page].map = NULL;
 118                bitmap->missing_pages++;
 119                kfree(ptr);
 120        }
 121}
 122
 123/*
 124 * bitmap file handling - read and write the bitmap file and its superblock
 125 */
 126
 127/*
 128 * basic page I/O operations
 129 */
 130
 131/* IO operations when bitmap is stored near all superblocks */
 132static int read_sb_page(struct mddev *mddev, loff_t offset,
 133                        struct page *page,
 134                        unsigned long index, int size)
 135{
 136        /* choose a good rdev and read the page from there */
 137
 138        struct md_rdev *rdev;
 139        sector_t target;
 140
 141        rdev_for_each(rdev, mddev) {
 142                if (! test_bit(In_sync, &rdev->flags)
 143                    || test_bit(Faulty, &rdev->flags))
 144                        continue;
 145
 146                target = offset + index * (PAGE_SIZE/512);
 147
 148                if (sync_page_io(rdev, target,
 149                                 roundup(size, bdev_logical_block_size(rdev->bdev)),
 150                                 page, READ, true)) {
 151                        page->index = index;
 152                        return 0;
 153                }
 154        }
 155        return -EIO;
 156}
 157
 158static struct md_rdev *next_active_rdev(struct md_rdev *rdev, struct mddev *mddev)
 159{
 160        /* Iterate the disks of an mddev, using rcu to protect access to the
 161         * linked list, and raising the refcount of devices we return to ensure
 162         * they don't disappear while in use.
 163         * As devices are only added or removed when raid_disk is < 0 and
 164         * nr_pending is 0 and In_sync is clear, the entries we return will
 165         * still be in the same position on the list when we re-enter
 166         * list_for_each_continue_rcu.
 167         */
 168        struct list_head *pos;
 169        rcu_read_lock();
 170        if (rdev == NULL)
 171                /* start at the beginning */
 172                pos = &mddev->disks;
 173        else {
 174                /* release the previous rdev and start from there. */
 175                rdev_dec_pending(rdev, mddev);
 176                pos = &rdev->same_set;
 177        }
 178        list_for_each_continue_rcu(pos, &mddev->disks) {
 179                rdev = list_entry(pos, struct md_rdev, same_set);
 180                if (rdev->raid_disk >= 0 &&
 181                    !test_bit(Faulty, &rdev->flags)) {
 182                        /* this is a usable devices */
 183                        atomic_inc(&rdev->nr_pending);
 184                        rcu_read_unlock();
 185                        return rdev;
 186                }
 187        }
 188        rcu_read_unlock();
 189        return NULL;
 190}
 191
 192static int write_sb_page(struct bitmap *bitmap, struct page *page, int wait)
 193{
 194        struct md_rdev *rdev = NULL;
 195        struct block_device *bdev;
 196        struct mddev *mddev = bitmap->mddev;
 197        struct bitmap_storage *store = &bitmap->storage;
 198
 199        while ((rdev = next_active_rdev(rdev, mddev)) != NULL) {
 200                int size = PAGE_SIZE;
 201                loff_t offset = mddev->bitmap_info.offset;
 202
 203                bdev = (rdev->meta_bdev) ? rdev->meta_bdev : rdev->bdev;
 204
 205                if (page->index == store->file_pages-1) {
 206                        int last_page_size = store->bytes & (PAGE_SIZE-1);
 207                        if (last_page_size == 0)
 208                                last_page_size = PAGE_SIZE;
 209                        size = roundup(last_page_size,
 210                                       bdev_logical_block_size(bdev));
 211                }
 212                /* Just make sure we aren't corrupting data or
 213                 * metadata
 214                 */
 215                if (mddev->external) {
 216                        /* Bitmap could be anywhere. */
 217                        if (rdev->sb_start + offset + (page->index
 218                                                       * (PAGE_SIZE/512))
 219                            > rdev->data_offset
 220                            &&
 221                            rdev->sb_start + offset
 222                            < (rdev->data_offset + mddev->dev_sectors
 223                             + (PAGE_SIZE/512)))
 224                                goto bad_alignment;
 225                } else if (offset < 0) {
 226                        /* DATA  BITMAP METADATA  */
 227                        if (offset
 228                            + (long)(page->index * (PAGE_SIZE/512))
 229                            + size/512 > 0)
 230                                /* bitmap runs in to metadata */
 231                                goto bad_alignment;
 232                        if (rdev->data_offset + mddev->dev_sectors
 233                            > rdev->sb_start + offset)
 234                                /* data runs in to bitmap */
 235                                goto bad_alignment;
 236                } else if (rdev->sb_start < rdev->data_offset) {
 237                        /* METADATA BITMAP DATA */
 238                        if (rdev->sb_start
 239                            + offset
 240                            + page->index*(PAGE_SIZE/512) + size/512
 241                            > rdev->data_offset)
 242                                /* bitmap runs in to data */
 243                                goto bad_alignment;
 244                } else {
 245                        /* DATA METADATA BITMAP - no problems */
 246                }
 247                md_super_write(mddev, rdev,
 248                               rdev->sb_start + offset
 249                               + page->index * (PAGE_SIZE/512),
 250                               size,
 251                               page);
 252        }
 253
 254        if (wait)
 255                md_super_wait(mddev);
 256        return 0;
 257
 258 bad_alignment:
 259        return -EINVAL;
 260}
 261
 262static void bitmap_file_kick(struct bitmap *bitmap);
 263/*
 264 * write out a page to a file
 265 */
 266static void write_page(struct bitmap *bitmap, struct page *page, int wait)
 267{
 268        struct buffer_head *bh;
 269
 270        if (bitmap->storage.file == NULL) {
 271                switch (write_sb_page(bitmap, page, wait)) {
 272                case -EINVAL:
 273                        set_bit(BITMAP_WRITE_ERROR, &bitmap->flags);
 274                }
 275        } else {
 276
 277                bh = page_buffers(page);
 278
 279                while (bh && bh->b_blocknr) {
 280                        atomic_inc(&bitmap->pending_writes);
 281                        set_buffer_locked(bh);
 282                        set_buffer_mapped(bh);
 283                        submit_bh(WRITE | REQ_SYNC, bh);
 284                        bh = bh->b_this_page;
 285                }
 286
 287                if (wait)
 288                        wait_event(bitmap->write_wait,
 289                                   atomic_read(&bitmap->pending_writes)==0);
 290        }
 291        if (test_bit(BITMAP_WRITE_ERROR, &bitmap->flags))
 292                bitmap_file_kick(bitmap);
 293}
 294
 295static void end_bitmap_write(struct buffer_head *bh, int uptodate)
 296{
 297        struct bitmap *bitmap = bh->b_private;
 298
 299        if (!uptodate)
 300                set_bit(BITMAP_WRITE_ERROR, &bitmap->flags);
 301        if (atomic_dec_and_test(&bitmap->pending_writes))
 302                wake_up(&bitmap->write_wait);
 303}
 304
 305/* copied from buffer.c */
 306static void
 307__clear_page_buffers(struct page *page)
 308{
 309        ClearPagePrivate(page);
 310        set_page_private(page, 0);
 311        page_cache_release(page);
 312}
 313static void free_buffers(struct page *page)
 314{
 315        struct buffer_head *bh;
 316
 317        if (!PagePrivate(page))
 318                return;
 319
 320        bh = page_buffers(page);
 321        while (bh) {
 322                struct buffer_head *next = bh->b_this_page;
 323                free_buffer_head(bh);
 324                bh = next;
 325        }
 326        __clear_page_buffers(page);
 327        put_page(page);
 328}
 329
 330/* read a page from a file.
 331 * We both read the page, and attach buffers to the page to record the
 332 * address of each block (using bmap).  These addresses will be used
 333 * to write the block later, completely bypassing the filesystem.
 334 * This usage is similar to how swap files are handled, and allows us
 335 * to write to a file with no concerns of memory allocation failing.
 336 */
 337static int read_page(struct file *file, unsigned long index,
 338                     struct bitmap *bitmap,
 339                     unsigned long count,
 340                     struct page *page)
 341{
 342        int ret = 0;
 343        struct inode *inode = file->f_path.dentry->d_inode;
 344        struct buffer_head *bh;
 345        sector_t block;
 346
 347        pr_debug("read bitmap file (%dB @ %llu)\n", (int)PAGE_SIZE,
 348                 (unsigned long long)index << PAGE_SHIFT);
 349
 350        bh = alloc_page_buffers(page, 1<<inode->i_blkbits, 0);
 351        if (!bh) {
 352                ret = -ENOMEM;
 353                goto out;
 354        }
 355        attach_page_buffers(page, bh);
 356        block = index << (PAGE_SHIFT - inode->i_blkbits);
 357        while (bh) {
 358                if (count == 0)
 359                        bh->b_blocknr = 0;
 360                else {
 361                        bh->b_blocknr = bmap(inode, block);
 362                        if (bh->b_blocknr == 0) {
 363                                /* Cannot use this file! */
 364                                ret = -EINVAL;
 365                                goto out;
 366                        }
 367                        bh->b_bdev = inode->i_sb->s_bdev;
 368                        if (count < (1<<inode->i_blkbits))
 369                                count = 0;
 370                        else
 371                                count -= (1<<inode->i_blkbits);
 372
 373                        bh->b_end_io = end_bitmap_write;
 374                        bh->b_private = bitmap;
 375                        atomic_inc(&bitmap->pending_writes);
 376                        set_buffer_locked(bh);
 377                        set_buffer_mapped(bh);
 378                        submit_bh(READ, bh);
 379                }
 380                block++;
 381                bh = bh->b_this_page;
 382        }
 383        page->index = index;
 384
 385        wait_event(bitmap->write_wait,
 386                   atomic_read(&bitmap->pending_writes)==0);
 387        if (test_bit(BITMAP_WRITE_ERROR, &bitmap->flags))
 388                ret = -EIO;
 389out:
 390        if (ret)
 391                printk(KERN_ALERT "md: bitmap read error: (%dB @ %llu): %d\n",
 392                        (int)PAGE_SIZE,
 393                        (unsigned long long)index << PAGE_SHIFT,
 394                        ret);
 395        return ret;
 396}
 397
 398/*
 399 * bitmap file superblock operations
 400 */
 401
 402/* update the event counter and sync the superblock to disk */
 403void bitmap_update_sb(struct bitmap *bitmap)
 404{
 405        bitmap_super_t *sb;
 406
 407        if (!bitmap || !bitmap->mddev) /* no bitmap for this array */
 408                return;
 409        if (bitmap->mddev->bitmap_info.external)
 410                return;
 411        if (!bitmap->storage.sb_page) /* no superblock */
 412                return;
 413        sb = kmap_atomic(bitmap->storage.sb_page);
 414        sb->events = cpu_to_le64(bitmap->mddev->events);
 415        if (bitmap->mddev->events < bitmap->events_cleared)
 416                /* rocking back to read-only */
 417                bitmap->events_cleared = bitmap->mddev->events;
 418        sb->events_cleared = cpu_to_le64(bitmap->events_cleared);
 419        sb->state = cpu_to_le32(bitmap->flags);
 420        /* Just in case these have been changed via sysfs: */
 421        sb->daemon_sleep = cpu_to_le32(bitmap->mddev->bitmap_info.daemon_sleep/HZ);
 422        sb->write_behind = cpu_to_le32(bitmap->mddev->bitmap_info.max_write_behind);
 423        /* This might have been changed by a reshape */
 424        sb->sync_size = cpu_to_le64(bitmap->mddev->resync_max_sectors);
 425        sb->chunksize = cpu_to_le32(bitmap->mddev->bitmap_info.chunksize);
 426        sb->sectors_reserved = cpu_to_le32(bitmap->mddev->
 427                                           bitmap_info.space);
 428        kunmap_atomic(sb);
 429        write_page(bitmap, bitmap->storage.sb_page, 1);
 430}
 431
 432/* print out the bitmap file superblock */
 433void bitmap_print_sb(struct bitmap *bitmap)
 434{
 435        bitmap_super_t *sb;
 436
 437        if (!bitmap || !bitmap->storage.sb_page)
 438                return;
 439        sb = kmap_atomic(bitmap->storage.sb_page);
 440        printk(KERN_DEBUG "%s: bitmap file superblock:\n", bmname(bitmap));
 441        printk(KERN_DEBUG "         magic: %08x\n", le32_to_cpu(sb->magic));
 442        printk(KERN_DEBUG "       version: %d\n", le32_to_cpu(sb->version));
 443        printk(KERN_DEBUG "          uuid: %08x.%08x.%08x.%08x\n",
 444                                        *(__u32 *)(sb->uuid+0),
 445                                        *(__u32 *)(sb->uuid+4),
 446                                        *(__u32 *)(sb->uuid+8),
 447                                        *(__u32 *)(sb->uuid+12));
 448        printk(KERN_DEBUG "        events: %llu\n",
 449                        (unsigned long long) le64_to_cpu(sb->events));
 450        printk(KERN_DEBUG "events cleared: %llu\n",
 451                        (unsigned long long) le64_to_cpu(sb->events_cleared));
 452        printk(KERN_DEBUG "         state: %08x\n", le32_to_cpu(sb->state));
 453        printk(KERN_DEBUG "     chunksize: %d B\n", le32_to_cpu(sb->chunksize));
 454        printk(KERN_DEBUG "  daemon sleep: %ds\n", le32_to_cpu(sb->daemon_sleep));
 455        printk(KERN_DEBUG "     sync size: %llu KB\n",
 456                        (unsigned long long)le64_to_cpu(sb->sync_size)/2);
 457        printk(KERN_DEBUG "max write behind: %d\n", le32_to_cpu(sb->write_behind));
 458        kunmap_atomic(sb);
 459}
 460
 461/*
 462 * bitmap_new_disk_sb
 463 * @bitmap
 464 *
 465 * This function is somewhat the reverse of bitmap_read_sb.  bitmap_read_sb
 466 * reads and verifies the on-disk bitmap superblock and populates bitmap_info.
 467 * This function verifies 'bitmap_info' and populates the on-disk bitmap
 468 * structure, which is to be written to disk.
 469 *
 470 * Returns: 0 on success, -Exxx on error
 471 */
 472static int bitmap_new_disk_sb(struct bitmap *bitmap)
 473{
 474        bitmap_super_t *sb;
 475        unsigned long chunksize, daemon_sleep, write_behind;
 476        int err = -EINVAL;
 477
 478        bitmap->storage.sb_page = alloc_page(GFP_KERNEL);
 479        if (IS_ERR(bitmap->storage.sb_page)) {
 480                err = PTR_ERR(bitmap->storage.sb_page);
 481                bitmap->storage.sb_page = NULL;
 482                return err;
 483        }
 484        bitmap->storage.sb_page->index = 0;
 485
 486        sb = kmap_atomic(bitmap->storage.sb_page);
 487
 488        sb->magic = cpu_to_le32(BITMAP_MAGIC);
 489        sb->version = cpu_to_le32(BITMAP_MAJOR_HI);
 490
 491        chunksize = bitmap->mddev->bitmap_info.chunksize;
 492        BUG_ON(!chunksize);
 493        if (!is_power_of_2(chunksize)) {
 494                kunmap_atomic(sb);
 495                printk(KERN_ERR "bitmap chunksize not a power of 2\n");
 496                return -EINVAL;
 497        }
 498        sb->chunksize = cpu_to_le32(chunksize);
 499
 500        daemon_sleep = bitmap->mddev->bitmap_info.daemon_sleep;
 501        if (!daemon_sleep ||
 502            (daemon_sleep < 1) || (daemon_sleep > MAX_SCHEDULE_TIMEOUT)) {
 503                printk(KERN_INFO "Choosing daemon_sleep default (5 sec)\n");
 504                daemon_sleep = 5 * HZ;
 505        }
 506        sb->daemon_sleep = cpu_to_le32(daemon_sleep);
 507        bitmap->mddev->bitmap_info.daemon_sleep = daemon_sleep;
 508
 509        /*
 510         * FIXME: write_behind for RAID1.  If not specified, what
 511         * is a good choice?  We choose COUNTER_MAX / 2 arbitrarily.
 512         */
 513        write_behind = bitmap->mddev->bitmap_info.max_write_behind;
 514        if (write_behind > COUNTER_MAX)
 515                write_behind = COUNTER_MAX / 2;
 516        sb->write_behind = cpu_to_le32(write_behind);
 517        bitmap->mddev->bitmap_info.max_write_behind = write_behind;
 518
 519        /* keep the array size field of the bitmap superblock up to date */
 520        sb->sync_size = cpu_to_le64(bitmap->mddev->resync_max_sectors);
 521
 522        memcpy(sb->uuid, bitmap->mddev->uuid, 16);
 523
 524        set_bit(BITMAP_STALE, &bitmap->flags);
 525        sb->state = cpu_to_le32(bitmap->flags);
 526        bitmap->events_cleared = bitmap->mddev->events;
 527        sb->events_cleared = cpu_to_le64(bitmap->mddev->events);
 528
 529        kunmap_atomic(sb);
 530
 531        return 0;
 532}
 533
 534/* read the superblock from the bitmap file and initialize some bitmap fields */
 535static int bitmap_read_sb(struct bitmap *bitmap)
 536{
 537        char *reason = NULL;
 538        bitmap_super_t *sb;
 539        unsigned long chunksize, daemon_sleep, write_behind;
 540        unsigned long long events;
 541        unsigned long sectors_reserved = 0;
 542        int err = -EINVAL;
 543        struct page *sb_page;
 544
 545        if (!bitmap->storage.file && !bitmap->mddev->bitmap_info.offset) {
 546                chunksize = 128 * 1024 * 1024;
 547                daemon_sleep = 5 * HZ;
 548                write_behind = 0;
 549                set_bit(BITMAP_STALE, &bitmap->flags);
 550                err = 0;
 551                goto out_no_sb;
 552        }
 553        /* page 0 is the superblock, read it... */
 554        sb_page = alloc_page(GFP_KERNEL);
 555        if (!sb_page)
 556                return -ENOMEM;
 557        bitmap->storage.sb_page = sb_page;
 558
 559        if (bitmap->storage.file) {
 560                loff_t isize = i_size_read(bitmap->storage.file->f_mapping->host);
 561                int bytes = isize > PAGE_SIZE ? PAGE_SIZE : isize;
 562
 563                err = read_page(bitmap->storage.file, 0,
 564                                bitmap, bytes, sb_page);
 565        } else {
 566                err = read_sb_page(bitmap->mddev,
 567                                   bitmap->mddev->bitmap_info.offset,
 568                                   sb_page,
 569                                   0, sizeof(bitmap_super_t));
 570        }
 571        if (err)
 572                return err;
 573
 574        sb = kmap_atomic(sb_page);
 575
 576        chunksize = le32_to_cpu(sb->chunksize);
 577        daemon_sleep = le32_to_cpu(sb->daemon_sleep) * HZ;
 578        write_behind = le32_to_cpu(sb->write_behind);
 579        sectors_reserved = le32_to_cpu(sb->sectors_reserved);
 580
 581        /* verify that the bitmap-specific fields are valid */
 582        if (sb->magic != cpu_to_le32(BITMAP_MAGIC))
 583                reason = "bad magic";
 584        else if (le32_to_cpu(sb->version) < BITMAP_MAJOR_LO ||
 585                 le32_to_cpu(sb->version) > BITMAP_MAJOR_HI)
 586                reason = "unrecognized superblock version";
 587        else if (chunksize < 512)
 588                reason = "bitmap chunksize too small";
 589        else if (!is_power_of_2(chunksize))
 590                reason = "bitmap chunksize not a power of 2";
 591        else if (daemon_sleep < 1 || daemon_sleep > MAX_SCHEDULE_TIMEOUT)
 592                reason = "daemon sleep period out of range";
 593        else if (write_behind > COUNTER_MAX)
 594                reason = "write-behind limit out of range (0 - 16383)";
 595        if (reason) {
 596                printk(KERN_INFO "%s: invalid bitmap file superblock: %s\n",
 597                        bmname(bitmap), reason);
 598                goto out;
 599        }
 600
 601        /* keep the array size field of the bitmap superblock up to date */
 602        sb->sync_size = cpu_to_le64(bitmap->mddev->resync_max_sectors);
 603
 604        if (bitmap->mddev->persistent) {
 605                /*
 606                 * We have a persistent array superblock, so compare the
 607                 * bitmap's UUID and event counter to the mddev's
 608                 */
 609                if (memcmp(sb->uuid, bitmap->mddev->uuid, 16)) {
 610                        printk(KERN_INFO
 611                               "%s: bitmap superblock UUID mismatch\n",
 612                               bmname(bitmap));
 613                        goto out;
 614                }
 615                events = le64_to_cpu(sb->events);
 616                if (events < bitmap->mddev->events) {
 617                        printk(KERN_INFO
 618                               "%s: bitmap file is out of date (%llu < %llu) "
 619                               "-- forcing full recovery\n",
 620                               bmname(bitmap), events,
 621                               (unsigned long long) bitmap->mddev->events);
 622                        set_bit(BITMAP_STALE, &bitmap->flags);
 623                }
 624        }
 625
 626        /* assign fields using values from superblock */
 627        bitmap->flags |= le32_to_cpu(sb->state);
 628        if (le32_to_cpu(sb->version) == BITMAP_MAJOR_HOSTENDIAN)
 629                set_bit(BITMAP_HOSTENDIAN, &bitmap->flags);
 630        bitmap->events_cleared = le64_to_cpu(sb->events_cleared);
 631        err = 0;
 632out:
 633        kunmap_atomic(sb);
 634out_no_sb:
 635        if (test_bit(BITMAP_STALE, &bitmap->flags))
 636                bitmap->events_cleared = bitmap->mddev->events;
 637        bitmap->mddev->bitmap_info.chunksize = chunksize;
 638        bitmap->mddev->bitmap_info.daemon_sleep = daemon_sleep;
 639        bitmap->mddev->bitmap_info.max_write_behind = write_behind;
 640        if (bitmap->mddev->bitmap_info.space == 0 ||
 641            bitmap->mddev->bitmap_info.space > sectors_reserved)
 642                bitmap->mddev->bitmap_info.space = sectors_reserved;
 643        if (err)
 644                bitmap_print_sb(bitmap);
 645        return err;
 646}
 647
 648/*
 649 * general bitmap file operations
 650 */
 651
 652/*
 653 * on-disk bitmap:
 654 *
 655 * Use one bit per "chunk" (block set). We do the disk I/O on the bitmap
 656 * file a page at a time. There's a superblock at the start of the file.
 657 */
 658/* calculate the index of the page that contains this bit */
 659static inline unsigned long file_page_index(struct bitmap_storage *store,
 660                                            unsigned long chunk)
 661{
 662        if (store->sb_page)
 663                chunk += sizeof(bitmap_super_t) << 3;
 664        return chunk >> PAGE_BIT_SHIFT;
 665}
 666
 667/* calculate the (bit) offset of this bit within a page */
 668static inline unsigned long file_page_offset(struct bitmap_storage *store,
 669                                             unsigned long chunk)
 670{
 671        if (store->sb_page)
 672                chunk += sizeof(bitmap_super_t) << 3;
 673        return chunk & (PAGE_BITS - 1);
 674}
 675
 676/*
 677 * return a pointer to the page in the filemap that contains the given bit
 678 *
 679 * this lookup is complicated by the fact that the bitmap sb might be exactly
 680 * 1 page (e.g., x86) or less than 1 page -- so the bitmap might start on page
 681 * 0 or page 1
 682 */
 683static inline struct page *filemap_get_page(struct bitmap_storage *store,
 684                                            unsigned long chunk)
 685{
 686        if (file_page_index(store, chunk) >= store->file_pages)
 687                return NULL;
 688        return store->filemap[file_page_index(store, chunk)
 689                              - file_page_index(store, 0)];
 690}
 691
 692static int bitmap_storage_alloc(struct bitmap_storage *store,
 693                                unsigned long chunks, int with_super)
 694{
 695        int pnum;
 696        unsigned long num_pages;
 697        unsigned long bytes;
 698
 699        bytes = DIV_ROUND_UP(chunks, 8);
 700        if (with_super)
 701                bytes += sizeof(bitmap_super_t);
 702
 703        num_pages = DIV_ROUND_UP(bytes, PAGE_SIZE);
 704
 705        store->filemap = kmalloc(sizeof(struct page *)
 706                                 * num_pages, GFP_KERNEL);
 707        if (!store->filemap)
 708                return -ENOMEM;
 709
 710        if (with_super && !store->sb_page) {
 711                store->sb_page = alloc_page(GFP_KERNEL|__GFP_ZERO);
 712                if (store->sb_page == NULL)
 713                        return -ENOMEM;
 714                store->sb_page->index = 0;
 715        }
 716        pnum = 0;
 717        if (store->sb_page) {
 718                store->filemap[0] = store->sb_page;
 719                pnum = 1;
 720        }
 721        for ( ; pnum < num_pages; pnum++) {
 722                store->filemap[pnum] = alloc_page(GFP_KERNEL|__GFP_ZERO);
 723                if (!store->filemap[pnum]) {
 724                        store->file_pages = pnum;
 725                        return -ENOMEM;
 726                }
 727                store->filemap[pnum]->index = pnum;
 728        }
 729        store->file_pages = pnum;
 730
 731        /* We need 4 bits per page, rounded up to a multiple
 732         * of sizeof(unsigned long) */
 733        store->filemap_attr = kzalloc(
 734                roundup(DIV_ROUND_UP(num_pages*4, 8), sizeof(unsigned long)),
 735                GFP_KERNEL);
 736        if (!store->filemap_attr)
 737                return -ENOMEM;
 738
 739        store->bytes = bytes;
 740
 741        return 0;
 742}
 743
 744static void bitmap_file_unmap(struct bitmap_storage *store)
 745{
 746        struct page **map, *sb_page;
 747        int pages;
 748        struct file *file;
 749
 750        file = store->file;
 751        map = store->filemap;
 752        pages = store->file_pages;
 753        sb_page = store->sb_page;
 754
 755        while (pages--)
 756                if (map[pages] != sb_page) /* 0 is sb_page, release it below */
 757                        free_buffers(map[pages]);
 758        kfree(map);
 759        kfree(store->filemap_attr);
 760
 761        if (sb_page)
 762                free_buffers(sb_page);
 763
 764        if (file) {
 765                struct inode *inode = file->f_path.dentry->d_inode;
 766                invalidate_mapping_pages(inode->i_mapping, 0, -1);
 767                fput(file);
 768        }
 769}
 770
 771/*
 772 * bitmap_file_kick - if an error occurs while manipulating the bitmap file
 773 * then it is no longer reliable, so we stop using it and we mark the file
 774 * as failed in the superblock
 775 */
 776static void bitmap_file_kick(struct bitmap *bitmap)
 777{
 778        char *path, *ptr = NULL;
 779
 780        if (!test_and_set_bit(BITMAP_STALE, &bitmap->flags)) {
 781                bitmap_update_sb(bitmap);
 782
 783                if (bitmap->storage.file) {
 784                        path = kmalloc(PAGE_SIZE, GFP_KERNEL);
 785                        if (path)
 786                                ptr = d_path(&bitmap->storage.file->f_path,
 787                                             path, PAGE_SIZE);
 788
 789                        printk(KERN_ALERT
 790                              "%s: kicking failed bitmap file %s from array!\n",
 791                              bmname(bitmap), IS_ERR(ptr) ? "" : ptr);
 792
 793                        kfree(path);
 794                } else
 795                        printk(KERN_ALERT
 796                               "%s: disabling internal bitmap due to errors\n",
 797                               bmname(bitmap));
 798        }
 799}
 800
 801enum bitmap_page_attr {
 802        BITMAP_PAGE_DIRTY = 0,     /* there are set bits that need to be synced */
 803        BITMAP_PAGE_PENDING = 1,   /* there are bits that are being cleaned.
 804                                    * i.e. counter is 1 or 2. */
 805        BITMAP_PAGE_NEEDWRITE = 2, /* there are cleared bits that need to be synced */
 806};
 807
 808static inline void set_page_attr(struct bitmap *bitmap, int pnum,
 809                                 enum bitmap_page_attr attr)
 810{
 811        set_bit((pnum<<2) + attr, bitmap->storage.filemap_attr);
 812}
 813
 814static inline void clear_page_attr(struct bitmap *bitmap, int pnum,
 815                                   enum bitmap_page_attr attr)
 816{
 817        clear_bit((pnum<<2) + attr, bitmap->storage.filemap_attr);
 818}
 819
 820static inline int test_page_attr(struct bitmap *bitmap, int pnum,
 821                                 enum bitmap_page_attr attr)
 822{
 823        return test_bit((pnum<<2) + attr, bitmap->storage.filemap_attr);
 824}
 825
 826static inline int test_and_clear_page_attr(struct bitmap *bitmap, int pnum,
 827                                           enum bitmap_page_attr attr)
 828{
 829        return test_and_clear_bit((pnum<<2) + attr,
 830                                  bitmap->storage.filemap_attr);
 831}
 832/*
 833 * bitmap_file_set_bit -- called before performing a write to the md device
 834 * to set (and eventually sync) a particular bit in the bitmap file
 835 *
 836 * we set the bit immediately, then we record the page number so that
 837 * when an unplug occurs, we can flush the dirty pages out to disk
 838 */
 839static void bitmap_file_set_bit(struct bitmap *bitmap, sector_t block)
 840{
 841        unsigned long bit;
 842        struct page *page;
 843        void *kaddr;
 844        unsigned long chunk = block >> bitmap->counts.chunkshift;
 845
 846        page = filemap_get_page(&bitmap->storage, chunk);
 847        if (!page)
 848                return;
 849        bit = file_page_offset(&bitmap->storage, chunk);
 850
 851        /* set the bit */
 852        kaddr = kmap_atomic(page);
 853        if (test_bit(BITMAP_HOSTENDIAN, &bitmap->flags))
 854                set_bit(bit, kaddr);
 855        else
 856                test_and_set_bit_le(bit, kaddr);
 857        kunmap_atomic(kaddr);
 858        pr_debug("set file bit %lu page %lu\n", bit, page->index);
 859        /* record page number so it gets flushed to disk when unplug occurs */
 860        set_page_attr(bitmap, page->index, BITMAP_PAGE_DIRTY);
 861}
 862
 863static void bitmap_file_clear_bit(struct bitmap *bitmap, sector_t block)
 864{
 865        unsigned long bit;
 866        struct page *page;
 867        void *paddr;
 868        unsigned long chunk = block >> bitmap->counts.chunkshift;
 869
 870        page = filemap_get_page(&bitmap->storage, chunk);
 871        if (!page)
 872                return;
 873        bit = file_page_offset(&bitmap->storage, chunk);
 874        paddr = kmap_atomic(page);
 875        if (test_bit(BITMAP_HOSTENDIAN, &bitmap->flags))
 876                clear_bit(bit, paddr);
 877        else
 878                test_and_clear_bit_le(bit, paddr);
 879        kunmap_atomic(paddr);
 880        if (!test_page_attr(bitmap, page->index, BITMAP_PAGE_NEEDWRITE)) {
 881                set_page_attr(bitmap, page->index, BITMAP_PAGE_PENDING);
 882                bitmap->allclean = 0;
 883        }
 884}
 885
 886/* this gets called when the md device is ready to unplug its underlying
 887 * (slave) device queues -- before we let any writes go down, we need to
 888 * sync the dirty pages of the bitmap file to disk */
 889void bitmap_unplug(struct bitmap *bitmap)
 890{
 891        unsigned long i;
 892        int dirty, need_write;
 893        int wait = 0;
 894
 895        if (!bitmap || !bitmap->storage.filemap ||
 896            test_bit(BITMAP_STALE, &bitmap->flags))
 897                return;
 898
 899        /* look at each page to see if there are any set bits that need to be
 900         * flushed out to disk */
 901        for (i = 0; i < bitmap->storage.file_pages; i++) {
 902                if (!bitmap->storage.filemap)
 903                        return;
 904                dirty = test_and_clear_page_attr(bitmap, i, BITMAP_PAGE_DIRTY);
 905                need_write = test_and_clear_page_attr(bitmap, i,
 906                                                      BITMAP_PAGE_NEEDWRITE);
 907                if (dirty || need_write) {
 908                        clear_page_attr(bitmap, i, BITMAP_PAGE_PENDING);
 909                        write_page(bitmap, bitmap->storage.filemap[i], 0);
 910                }
 911                if (dirty)
 912                        wait = 1;
 913        }
 914        if (wait) { /* if any writes were performed, we need to wait on them */
 915                if (bitmap->storage.file)
 916                        wait_event(bitmap->write_wait,
 917                                   atomic_read(&bitmap->pending_writes)==0);
 918                else
 919                        md_super_wait(bitmap->mddev);
 920        }
 921        if (test_bit(BITMAP_WRITE_ERROR, &bitmap->flags))
 922                bitmap_file_kick(bitmap);
 923}
 924EXPORT_SYMBOL(bitmap_unplug);
 925
 926static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset, int needed);
 927/* * bitmap_init_from_disk -- called at bitmap_create time to initialize
 928 * the in-memory bitmap from the on-disk bitmap -- also, sets up the
 929 * memory mapping of the bitmap file
 930 * Special cases:
 931 *   if there's no bitmap file, or if the bitmap file had been
 932 *   previously kicked from the array, we mark all the bits as
 933 *   1's in order to cause a full resync.
 934 *
 935 * We ignore all bits for sectors that end earlier than 'start'.
 936 * This is used when reading an out-of-date bitmap...
 937 */
 938static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
 939{
 940        unsigned long i, chunks, index, oldindex, bit;
 941        struct page *page = NULL;
 942        unsigned long bit_cnt = 0;
 943        struct file *file;
 944        unsigned long offset;
 945        int outofdate;
 946        int ret = -ENOSPC;
 947        void *paddr;
 948        struct bitmap_storage *store = &bitmap->storage;
 949
 950        chunks = bitmap->counts.chunks;
 951        file = store->file;
 952
 953        if (!file && !bitmap->mddev->bitmap_info.offset) {
 954                /* No permanent bitmap - fill with '1s'. */
 955                store->filemap = NULL;
 956                store->file_pages = 0;
 957                for (i = 0; i < chunks ; i++) {
 958                        /* if the disk bit is set, set the memory bit */
 959                        int needed = ((sector_t)(i+1) << (bitmap->counts.chunkshift)
 960                                      >= start);
 961                        bitmap_set_memory_bits(bitmap,
 962                                               (sector_t)i << bitmap->counts.chunkshift,
 963                                               needed);
 964                }
 965                return 0;
 966        }
 967
 968        outofdate = test_bit(BITMAP_STALE, &bitmap->flags);
 969        if (outofdate)
 970                printk(KERN_INFO "%s: bitmap file is out of date, doing full "
 971                        "recovery\n", bmname(bitmap));
 972
 973        if (file && i_size_read(file->f_mapping->host) < store->bytes) {
 974                printk(KERN_INFO "%s: bitmap file too short %lu < %lu\n",
 975                       bmname(bitmap),
 976                       (unsigned long) i_size_read(file->f_mapping->host),
 977                       store->bytes);
 978                goto err;
 979        }
 980
 981        oldindex = ~0L;
 982        offset = 0;
 983        if (!bitmap->mddev->bitmap_info.external)
 984                offset = sizeof(bitmap_super_t);
 985
 986        for (i = 0; i < chunks; i++) {
 987                int b;
 988                index = file_page_index(&bitmap->storage, i);
 989                bit = file_page_offset(&bitmap->storage, i);
 990                if (index != oldindex) { /* this is a new page, read it in */
 991                        int count;
 992                        /* unmap the old page, we're done with it */
 993                        if (index == store->file_pages-1)
 994                                count = store->bytes - index * PAGE_SIZE;
 995                        else
 996                                count = PAGE_SIZE;
 997                        page = store->filemap[index];
 998                        if (file)
 999                                ret = read_page(file, index, bitmap,
1000                                                count, page);
1001                        else
1002                                ret = read_sb_page(
1003                                        bitmap->mddev,
1004                                        bitmap->mddev->bitmap_info.offset,
1005                                        page,
1006                                        index, count);
1007
1008                        if (ret)
1009                                goto err;
1010
1011                        oldindex = index;
1012
1013                        if (outofdate) {
1014                                /*
1015                                 * if bitmap is out of date, dirty the
1016                                 * whole page and write it out
1017                                 */
1018                                paddr = kmap_atomic(page);
1019                                memset(paddr + offset, 0xff,
1020                                       PAGE_SIZE - offset);
1021                                kunmap_atomic(paddr);
1022                                write_page(bitmap, page, 1);
1023
1024                                ret = -EIO;
1025                                if (test_bit(BITMAP_WRITE_ERROR,
1026                                             &bitmap->flags))
1027                                        goto err;
1028                        }
1029                }
1030                paddr = kmap_atomic(page);
1031                if (test_bit(BITMAP_HOSTENDIAN, &bitmap->flags))
1032                        b = test_bit(bit, paddr);
1033                else
1034                        b = test_bit_le(bit, paddr);
1035                kunmap_atomic(paddr);
1036                if (b) {
1037                        /* if the disk bit is set, set the memory bit */
1038                        int needed = ((sector_t)(i+1) << bitmap->counts.chunkshift
1039                                      >= start);
1040                        bitmap_set_memory_bits(bitmap,
1041                                               (sector_t)i << bitmap->counts.chunkshift,
1042                                               needed);
1043                        bit_cnt++;
1044                }
1045                offset = 0;
1046        }
1047
1048        printk(KERN_INFO "%s: bitmap initialized from disk: "
1049               "read %lu pages, set %lu of %lu bits\n",
1050               bmname(bitmap), store->file_pages,
1051               bit_cnt, chunks);
1052
1053        return 0;
1054
1055 err:
1056        printk(KERN_INFO "%s: bitmap initialisation failed: %d\n",
1057               bmname(bitmap), ret);
1058        return ret;
1059}
1060
1061void bitmap_write_all(struct bitmap *bitmap)
1062{
1063        /* We don't actually write all bitmap blocks here,
1064         * just flag them as needing to be written
1065         */
1066        int i;
1067
1068        if (!bitmap || !bitmap->storage.filemap)
1069                return;
1070        if (bitmap->storage.file)
1071                /* Only one copy, so nothing needed */
1072                return;
1073
1074        for (i = 0; i < bitmap->storage.file_pages; i++)
1075                set_page_attr(bitmap, i,
1076                              BITMAP_PAGE_NEEDWRITE);
1077        bitmap->allclean = 0;
1078}
1079
1080static void bitmap_count_page(struct bitmap_counts *bitmap,
1081                              sector_t offset, int inc)
1082{
1083        sector_t chunk = offset >> bitmap->chunkshift;
1084        unsigned long page = chunk >> PAGE_COUNTER_SHIFT;
1085        bitmap->bp[page].count += inc;
1086        bitmap_checkfree(bitmap, page);
1087}
1088
1089static void bitmap_set_pending(struct bitmap_counts *bitmap, sector_t offset)
1090{
1091        sector_t chunk = offset >> bitmap->chunkshift;
1092        unsigned long page = chunk >> PAGE_COUNTER_SHIFT;
1093        struct bitmap_page *bp = &bitmap->bp[page];
1094
1095        if (!bp->pending)
1096                bp->pending = 1;
1097}
1098
1099static bitmap_counter_t *bitmap_get_counter(struct bitmap_counts *bitmap,
1100                                            sector_t offset, sector_t *blocks,
1101                                            int create);
1102
1103/*
1104 * bitmap daemon -- periodically wakes up to clean bits and flush pages
1105 *                      out to disk
1106 */
1107
1108void bitmap_daemon_work(struct mddev *mddev)
1109{
1110        struct bitmap *bitmap;
1111        unsigned long j;
1112        unsigned long nextpage;
1113        sector_t blocks;
1114        struct bitmap_counts *counts;
1115
1116        /* Use a mutex to guard daemon_work against
1117         * bitmap_destroy.
1118         */
1119        mutex_lock(&mddev->bitmap_info.mutex);
1120        bitmap = mddev->bitmap;
1121        if (bitmap == NULL) {
1122                mutex_unlock(&mddev->bitmap_info.mutex);
1123                return;
1124        }
1125        if (time_before(jiffies, bitmap->daemon_lastrun
1126                        + mddev->bitmap_info.daemon_sleep))
1127                goto done;
1128
1129        bitmap->daemon_lastrun = jiffies;
1130        if (bitmap->allclean) {
1131                mddev->thread->timeout = MAX_SCHEDULE_TIMEOUT;
1132                goto done;
1133        }
1134        bitmap->allclean = 1;
1135
1136        /* Any file-page which is PENDING now needs to be written.
1137         * So set NEEDWRITE now, then after we make any last-minute changes
1138         * we will write it.
1139         */
1140        for (j = 0; j < bitmap->storage.file_pages; j++)
1141                if (test_and_clear_page_attr(bitmap, j,
1142                                             BITMAP_PAGE_PENDING))
1143                        set_page_attr(bitmap, j,
1144                                      BITMAP_PAGE_NEEDWRITE);
1145
1146        if (bitmap->need_sync &&
1147            mddev->bitmap_info.external == 0) {
1148                /* Arrange for superblock update as well as
1149                 * other changes */
1150                bitmap_super_t *sb;
1151                bitmap->need_sync = 0;
1152                if (bitmap->storage.filemap) {
1153                        sb = kmap_atomic(bitmap->storage.sb_page);
1154                        sb->events_cleared =
1155                                cpu_to_le64(bitmap->events_cleared);
1156                        kunmap_atomic(sb);
1157                        set_page_attr(bitmap, 0,
1158                                      BITMAP_PAGE_NEEDWRITE);
1159                }
1160        }
1161        /* Now look at the bitmap counters and if any are '2' or '1',
1162         * decrement and handle accordingly.
1163         */
1164        counts = &bitmap->counts;
1165        spin_lock_irq(&counts->lock);
1166        nextpage = 0;
1167        for (j = 0; j < counts->chunks; j++) {
1168                bitmap_counter_t *bmc;
1169                sector_t  block = (sector_t)j << counts->chunkshift;
1170
1171                if (j == nextpage) {
1172                        nextpage += PAGE_COUNTER_RATIO;
1173                        if (!counts->bp[j >> PAGE_COUNTER_SHIFT].pending) {
1174                                j |= PAGE_COUNTER_MASK;
1175                                continue;
1176                        }
1177                        counts->bp[j >> PAGE_COUNTER_SHIFT].pending = 0;
1178                }
1179                bmc = bitmap_get_counter(counts,
1180                                         block,
1181                                         &blocks, 0);
1182
1183                if (!bmc) {
1184                        j |= PAGE_COUNTER_MASK;
1185                        continue;
1186                }
1187                if (*bmc == 1 && !bitmap->need_sync) {
1188                        /* We can clear the bit */
1189                        *bmc = 0;
1190                        bitmap_count_page(counts, block, -1);
1191                        bitmap_file_clear_bit(bitmap, block);
1192                } else if (*bmc && *bmc <= 2) {
1193                        *bmc = 1;
1194                        bitmap_set_pending(counts, block);
1195                        bitmap->allclean = 0;
1196                }
1197        }
1198        spin_unlock_irq(&counts->lock);
1199
1200        /* Now start writeout on any page in NEEDWRITE that isn't DIRTY.
1201         * DIRTY pages need to be written by bitmap_unplug so it can wait
1202         * for them.
1203         * If we find any DIRTY page we stop there and let bitmap_unplug
1204         * handle all the rest.  This is important in the case where
1205         * the first blocking holds the superblock and it has been updated.
1206         * We mustn't write any other blocks before the superblock.
1207         */
1208        for (j = 0;
1209             j < bitmap->storage.file_pages
1210                     && !test_bit(BITMAP_STALE, &bitmap->flags);
1211             j++) {
1212
1213                if (test_page_attr(bitmap, j,
1214                                   BITMAP_PAGE_DIRTY))
1215                        /* bitmap_unplug will handle the rest */
1216                        break;
1217                if (test_and_clear_page_attr(bitmap, j,
1218                                             BITMAP_PAGE_NEEDWRITE)) {
1219                        write_page(bitmap, bitmap->storage.filemap[j], 0);
1220                }
1221        }
1222
1223 done:
1224        if (bitmap->allclean == 0)
1225                mddev->thread->timeout =
1226                        mddev->bitmap_info.daemon_sleep;
1227        mutex_unlock(&mddev->bitmap_info.mutex);
1228}
1229
1230static bitmap_counter_t *bitmap_get_counter(struct bitmap_counts *bitmap,
1231                                            sector_t offset, sector_t *blocks,
1232                                            int create)
1233__releases(bitmap->lock)
1234__acquires(bitmap->lock)
1235{
1236        /* If 'create', we might release the lock and reclaim it.
1237         * The lock must have been taken with interrupts enabled.
1238         * If !create, we don't release the lock.
1239         */
1240        sector_t chunk = offset >> bitmap->chunkshift;
1241        unsigned long page = chunk >> PAGE_COUNTER_SHIFT;
1242        unsigned long pageoff = (chunk & PAGE_COUNTER_MASK) << COUNTER_BYTE_SHIFT;
1243        sector_t csize;
1244        int err;
1245
1246        err = bitmap_checkpage(bitmap, page, create);
1247
1248        if (bitmap->bp[page].hijacked ||
1249            bitmap->bp[page].map == NULL)
1250                csize = ((sector_t)1) << (bitmap->chunkshift +
1251                                          PAGE_COUNTER_SHIFT - 1);
1252        else
1253                csize = ((sector_t)1) << bitmap->chunkshift;
1254        *blocks = csize - (offset & (csize - 1));
1255
1256        if (err < 0)
1257                return NULL;
1258
1259        /* now locked ... */
1260
1261        if (bitmap->bp[page].hijacked) { /* hijacked pointer */
1262                /* should we use the first or second counter field
1263                 * of the hijacked pointer? */
1264                int hi = (pageoff > PAGE_COUNTER_MASK);
1265                return  &((bitmap_counter_t *)
1266                          &bitmap->bp[page].map)[hi];
1267        } else /* page is allocated */
1268                return (bitmap_counter_t *)
1269                        &(bitmap->bp[page].map[pageoff]);
1270}
1271
1272int bitmap_startwrite(struct bitmap *bitmap, sector_t offset, unsigned long sectors, int behind)
1273{
1274        if (!bitmap)
1275                return 0;
1276
1277        if (behind) {
1278                int bw;
1279                atomic_inc(&bitmap->behind_writes);
1280                bw = atomic_read(&bitmap->behind_writes);
1281                if (bw > bitmap->behind_writes_used)
1282                        bitmap->behind_writes_used = bw;
1283
1284                pr_debug("inc write-behind count %d/%lu\n",
1285                         bw, bitmap->mddev->bitmap_info.max_write_behind);
1286        }
1287
1288        while (sectors) {
1289                sector_t blocks;
1290                bitmap_counter_t *bmc;
1291
1292                spin_lock_irq(&bitmap->counts.lock);
1293                bmc = bitmap_get_counter(&bitmap->counts, offset, &blocks, 1);
1294                if (!bmc) {
1295                        spin_unlock_irq(&bitmap->counts.lock);
1296                        return 0;
1297                }
1298
1299                if (unlikely(COUNTER(*bmc) == COUNTER_MAX)) {
1300                        DEFINE_WAIT(__wait);
1301                        /* note that it is safe to do the prepare_to_wait
1302                         * after the test as long as we do it before dropping
1303                         * the spinlock.
1304                         */
1305                        prepare_to_wait(&bitmap->overflow_wait, &__wait,
1306                                        TASK_UNINTERRUPTIBLE);
1307                        spin_unlock_irq(&bitmap->counts.lock);
1308                        schedule();
1309                        finish_wait(&bitmap->overflow_wait, &__wait);
1310                        continue;
1311                }
1312
1313                switch (*bmc) {
1314                case 0:
1315                        bitmap_file_set_bit(bitmap, offset);
1316                        bitmap_count_page(&bitmap->counts, offset, 1);
1317                        /* fall through */
1318                case 1:
1319                        *bmc = 2;
1320                }
1321
1322                (*bmc)++;
1323
1324                spin_unlock_irq(&bitmap->counts.lock);
1325
1326                offset += blocks;
1327                if (sectors > blocks)
1328                        sectors -= blocks;
1329                else
1330                        sectors = 0;
1331        }
1332        return 0;
1333}
1334EXPORT_SYMBOL(bitmap_startwrite);
1335
1336void bitmap_endwrite(struct bitmap *bitmap, sector_t offset, unsigned long sectors,
1337                     int success, int behind)
1338{
1339        if (!bitmap)
1340                return;
1341        if (behind) {
1342                if (atomic_dec_and_test(&bitmap->behind_writes))
1343                        wake_up(&bitmap->behind_wait);
1344                pr_debug("dec write-behind count %d/%lu\n",
1345                         atomic_read(&bitmap->behind_writes),
1346                         bitmap->mddev->bitmap_info.max_write_behind);
1347        }
1348
1349        while (sectors) {
1350                sector_t blocks;
1351                unsigned long flags;
1352                bitmap_counter_t *bmc;
1353
1354                spin_lock_irqsave(&bitmap->counts.lock, flags);
1355                bmc = bitmap_get_counter(&bitmap->counts, offset, &blocks, 0);
1356                if (!bmc) {
1357                        spin_unlock_irqrestore(&bitmap->counts.lock, flags);
1358                        return;
1359                }
1360
1361                if (success && !bitmap->mddev->degraded &&
1362                    bitmap->events_cleared < bitmap->mddev->events) {
1363                        bitmap->events_cleared = bitmap->mddev->events;
1364                        bitmap->need_sync = 1;
1365                        sysfs_notify_dirent_safe(bitmap->sysfs_can_clear);
1366                }
1367
1368                if (!success && !NEEDED(*bmc))
1369                        *bmc |= NEEDED_MASK;
1370
1371                if (COUNTER(*bmc) == COUNTER_MAX)
1372                        wake_up(&bitmap->overflow_wait);
1373
1374                (*bmc)--;
1375                if (*bmc <= 2) {
1376                        bitmap_set_pending(&bitmap->counts, offset);
1377                        bitmap->allclean = 0;
1378                }
1379                spin_unlock_irqrestore(&bitmap->counts.lock, flags);
1380                offset += blocks;
1381                if (sectors > blocks)
1382                        sectors -= blocks;
1383                else
1384                        sectors = 0;
1385        }
1386}
1387EXPORT_SYMBOL(bitmap_endwrite);
1388
1389static int __bitmap_start_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks,
1390                               int degraded)
1391{
1392        bitmap_counter_t *bmc;
1393        int rv;
1394        if (bitmap == NULL) {/* FIXME or bitmap set as 'failed' */
1395                *blocks = 1024;
1396                return 1; /* always resync if no bitmap */
1397        }
1398        spin_lock_irq(&bitmap->counts.lock);
1399        bmc = bitmap_get_counter(&bitmap->counts, offset, blocks, 0);
1400        rv = 0;
1401        if (bmc) {
1402                /* locked */
1403                if (RESYNC(*bmc))
1404                        rv = 1;
1405                else if (NEEDED(*bmc)) {
1406                        rv = 1;
1407                        if (!degraded) { /* don't set/clear bits if degraded */
1408                                *bmc |= RESYNC_MASK;
1409                                *bmc &= ~NEEDED_MASK;
1410                        }
1411                }
1412        }
1413        spin_unlock_irq(&bitmap->counts.lock);
1414        return rv;
1415}
1416
1417int bitmap_start_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks,
1418                      int degraded)
1419{
1420        /* bitmap_start_sync must always report on multiples of whole
1421         * pages, otherwise resync (which is very PAGE_SIZE based) will
1422         * get confused.
1423         * So call __bitmap_start_sync repeatedly (if needed) until
1424         * At least PAGE_SIZE>>9 blocks are covered.
1425         * Return the 'or' of the result.
1426         */
1427        int rv = 0;
1428        sector_t blocks1;
1429
1430        *blocks = 0;
1431        while (*blocks < (PAGE_SIZE>>9)) {
1432                rv |= __bitmap_start_sync(bitmap, offset,
1433                                          &blocks1, degraded);
1434                offset += blocks1;
1435                *blocks += blocks1;
1436        }
1437        return rv;
1438}
1439EXPORT_SYMBOL(bitmap_start_sync);
1440
1441void bitmap_end_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks, int aborted)
1442{
1443        bitmap_counter_t *bmc;
1444        unsigned long flags;
1445
1446        if (bitmap == NULL) {
1447                *blocks = 1024;
1448                return;
1449        }
1450        spin_lock_irqsave(&bitmap->counts.lock, flags);
1451        bmc = bitmap_get_counter(&bitmap->counts, offset, blocks, 0);
1452        if (bmc == NULL)
1453                goto unlock;
1454        /* locked */
1455        if (RESYNC(*bmc)) {
1456                *bmc &= ~RESYNC_MASK;
1457
1458                if (!NEEDED(*bmc) && aborted)
1459                        *bmc |= NEEDED_MASK;
1460                else {
1461                        if (*bmc <= 2) {
1462                                bitmap_set_pending(&bitmap->counts, offset);
1463                                bitmap->allclean = 0;
1464                        }
1465                }
1466        }
1467 unlock:
1468        spin_unlock_irqrestore(&bitmap->counts.lock, flags);
1469}
1470EXPORT_SYMBOL(bitmap_end_sync);
1471
1472void bitmap_close_sync(struct bitmap *bitmap)
1473{
1474        /* Sync has finished, and any bitmap chunks that weren't synced
1475         * properly have been aborted.  It remains to us to clear the
1476         * RESYNC bit wherever it is still on
1477         */
1478        sector_t sector = 0;
1479        sector_t blocks;
1480        if (!bitmap)
1481                return;
1482        while (sector < bitmap->mddev->resync_max_sectors) {
1483                bitmap_end_sync(bitmap, sector, &blocks, 0);
1484                sector += blocks;
1485        }
1486}
1487EXPORT_SYMBOL(bitmap_close_sync);
1488
1489void bitmap_cond_end_sync(struct bitmap *bitmap, sector_t sector)
1490{
1491        sector_t s = 0;
1492        sector_t blocks;
1493
1494        if (!bitmap)
1495                return;
1496        if (sector == 0) {
1497                bitmap->last_end_sync = jiffies;
1498                return;
1499        }
1500        if (time_before(jiffies, (bitmap->last_end_sync
1501                                  + bitmap->mddev->bitmap_info.daemon_sleep)))
1502                return;
1503        wait_event(bitmap->mddev->recovery_wait,
1504                   atomic_read(&bitmap->mddev->recovery_active) == 0);
1505
1506        bitmap->mddev->curr_resync_completed = sector;
1507        set_bit(MD_CHANGE_CLEAN, &bitmap->mddev->flags);
1508        sector &= ~((1ULL << bitmap->counts.chunkshift) - 1);
1509        s = 0;
1510        while (s < sector && s < bitmap->mddev->resync_max_sectors) {
1511                bitmap_end_sync(bitmap, s, &blocks, 0);
1512                s += blocks;
1513        }
1514        bitmap->last_end_sync = jiffies;
1515        sysfs_notify(&bitmap->mddev->kobj, NULL, "sync_completed");
1516}
1517EXPORT_SYMBOL(bitmap_cond_end_sync);
1518
1519static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset, int needed)
1520{
1521        /* For each chunk covered by any of these sectors, set the
1522         * counter to 2 and possibly set resync_needed.  They should all
1523         * be 0 at this point
1524         */
1525
1526        sector_t secs;
1527        bitmap_counter_t *bmc;
1528        spin_lock_irq(&bitmap->counts.lock);
1529        bmc = bitmap_get_counter(&bitmap->counts, offset, &secs, 1);
1530        if (!bmc) {
1531                spin_unlock_irq(&bitmap->counts.lock);
1532                return;
1533        }
1534        if (!*bmc) {
1535                *bmc = 2 | (needed ? NEEDED_MASK : 0);
1536                bitmap_count_page(&bitmap->counts, offset, 1);
1537                bitmap_set_pending(&bitmap->counts, offset);
1538                bitmap->allclean = 0;
1539        }
1540        spin_unlock_irq(&bitmap->counts.lock);
1541}
1542
1543/* dirty the memory and file bits for bitmap chunks "s" to "e" */
1544void bitmap_dirty_bits(struct bitmap *bitmap, unsigned long s, unsigned long e)
1545{
1546        unsigned long chunk;
1547
1548        for (chunk = s; chunk <= e; chunk++) {
1549                sector_t sec = (sector_t)chunk << bitmap->counts.chunkshift;
1550                bitmap_set_memory_bits(bitmap, sec, 1);
1551                bitmap_file_set_bit(bitmap, sec);
1552                if (sec < bitmap->mddev->recovery_cp)
1553                        /* We are asserting that the array is dirty,
1554                         * so move the recovery_cp address back so
1555                         * that it is obvious that it is dirty
1556                         */
1557                        bitmap->mddev->recovery_cp = sec;
1558        }
1559}
1560
1561/*
1562 * flush out any pending updates
1563 */
1564void bitmap_flush(struct mddev *mddev)
1565{
1566        struct bitmap *bitmap = mddev->bitmap;
1567        long sleep;
1568
1569        if (!bitmap) /* there was no bitmap */
1570                return;
1571
1572        /* run the daemon_work three time to ensure everything is flushed
1573         * that can be
1574         */
1575        sleep = mddev->bitmap_info.daemon_sleep * 2;
1576        bitmap->daemon_lastrun -= sleep;
1577        bitmap_daemon_work(mddev);
1578        bitmap->daemon_lastrun -= sleep;
1579        bitmap_daemon_work(mddev);
1580        bitmap->daemon_lastrun -= sleep;
1581        bitmap_daemon_work(mddev);
1582        bitmap_update_sb(bitmap);
1583}
1584
1585/*
1586 * free memory that was allocated
1587 */
1588static void bitmap_free(struct bitmap *bitmap)
1589{
1590        unsigned long k, pages;
1591        struct bitmap_page *bp;
1592
1593        if (!bitmap) /* there was no bitmap */
1594                return;
1595
1596        /* Shouldn't be needed - but just in case.... */
1597        wait_event(bitmap->write_wait,
1598                   atomic_read(&bitmap->pending_writes) == 0);
1599
1600        /* release the bitmap file  */
1601        bitmap_file_unmap(&bitmap->storage);
1602
1603        bp = bitmap->counts.bp;
1604        pages = bitmap->counts.pages;
1605
1606        /* free all allocated memory */
1607
1608        if (bp) /* deallocate the page memory */
1609                for (k = 0; k < pages; k++)
1610                        if (bp[k].map && !bp[k].hijacked)
1611                                kfree(bp[k].map);
1612        kfree(bp);
1613        kfree(bitmap);
1614}
1615
1616void bitmap_destroy(struct mddev *mddev)
1617{
1618        struct bitmap *bitmap = mddev->bitmap;
1619
1620        if (!bitmap) /* there was no bitmap */
1621                return;
1622
1623        mutex_lock(&mddev->bitmap_info.mutex);
1624        mddev->bitmap = NULL; /* disconnect from the md device */
1625        mutex_unlock(&mddev->bitmap_info.mutex);
1626        if (mddev->thread)
1627                mddev->thread->timeout = MAX_SCHEDULE_TIMEOUT;
1628
1629        if (bitmap->sysfs_can_clear)
1630                sysfs_put(bitmap->sysfs_can_clear);
1631
1632        bitmap_free(bitmap);
1633}
1634
1635/*
1636 * initialize the bitmap structure
1637 * if this returns an error, bitmap_destroy must be called to do clean up
1638 */
1639int bitmap_create(struct mddev *mddev)
1640{
1641        struct bitmap *bitmap;
1642        sector_t blocks = mddev->resync_max_sectors;
1643        struct file *file = mddev->bitmap_info.file;
1644        int err;
1645        struct sysfs_dirent *bm = NULL;
1646
1647        BUILD_BUG_ON(sizeof(bitmap_super_t) != 256);
1648
1649        BUG_ON(file && mddev->bitmap_info.offset);
1650
1651        bitmap = kzalloc(sizeof(*bitmap), GFP_KERNEL);
1652        if (!bitmap)
1653                return -ENOMEM;
1654
1655        spin_lock_init(&bitmap->counts.lock);
1656        atomic_set(&bitmap->pending_writes, 0);
1657        init_waitqueue_head(&bitmap->write_wait);
1658        init_waitqueue_head(&bitmap->overflow_wait);
1659        init_waitqueue_head(&bitmap->behind_wait);
1660
1661        bitmap->mddev = mddev;
1662
1663        if (mddev->kobj.sd)
1664                bm = sysfs_get_dirent(mddev->kobj.sd, NULL, "bitmap");
1665        if (bm) {
1666                bitmap->sysfs_can_clear = sysfs_get_dirent(bm, NULL, "can_clear");
1667                sysfs_put(bm);
1668        } else
1669                bitmap->sysfs_can_clear = NULL;
1670
1671        bitmap->storage.file = file;
1672        if (file) {
1673                get_file(file);
1674                /* As future accesses to this file will use bmap,
1675                 * and bypass the page cache, we must sync the file
1676                 * first.
1677                 */
1678                vfs_fsync(file, 1);
1679        }
1680        /* read superblock from bitmap file (this sets mddev->bitmap_info.chunksize) */
1681        if (!mddev->bitmap_info.external) {
1682                /*
1683                 * If 'MD_ARRAY_FIRST_USE' is set, then device-mapper is
1684                 * instructing us to create a new on-disk bitmap instance.
1685                 */
1686                if (test_and_clear_bit(MD_ARRAY_FIRST_USE, &mddev->flags))
1687                        err = bitmap_new_disk_sb(bitmap);
1688                else
1689                        err = bitmap_read_sb(bitmap);
1690        } else {
1691                err = 0;
1692                if (mddev->bitmap_info.chunksize == 0 ||
1693                    mddev->bitmap_info.daemon_sleep == 0)
1694                        /* chunksize and time_base need to be
1695                         * set first. */
1696                        err = -EINVAL;
1697        }
1698        if (err)
1699                goto error;
1700
1701        bitmap->daemon_lastrun = jiffies;
1702        err = bitmap_resize(bitmap, blocks, mddev->bitmap_info.chunksize, 1);
1703        if (err)
1704                goto error;
1705
1706        printk(KERN_INFO "created bitmap (%lu pages) for device %s\n",
1707               bitmap->counts.pages, bmname(bitmap));
1708
1709        mddev->bitmap = bitmap;
1710        return test_bit(BITMAP_WRITE_ERROR, &bitmap->flags) ? -EIO : 0;
1711
1712 error:
1713        bitmap_free(bitmap);
1714        return err;
1715}
1716
1717int bitmap_load(struct mddev *mddev)
1718{
1719        int err = 0;
1720        sector_t start = 0;
1721        sector_t sector = 0;
1722        struct bitmap *bitmap = mddev->bitmap;
1723
1724        if (!bitmap)
1725                goto out;
1726
1727        /* Clear out old bitmap info first:  Either there is none, or we
1728         * are resuming after someone else has possibly changed things,
1729         * so we should forget old cached info.
1730         * All chunks should be clean, but some might need_sync.
1731         */
1732        while (sector < mddev->resync_max_sectors) {
1733                sector_t blocks;
1734                bitmap_start_sync(bitmap, sector, &blocks, 0);
1735                sector += blocks;
1736        }
1737        bitmap_close_sync(bitmap);
1738
1739        if (mddev->degraded == 0
1740            || bitmap->events_cleared == mddev->events)
1741                /* no need to keep dirty bits to optimise a
1742                 * re-add of a missing device */
1743                start = mddev->recovery_cp;
1744
1745        mutex_lock(&mddev->bitmap_info.mutex);
1746        err = bitmap_init_from_disk(bitmap, start);
1747        mutex_unlock(&mddev->bitmap_info.mutex);
1748
1749        if (err)
1750                goto out;
1751        clear_bit(BITMAP_STALE, &bitmap->flags);
1752
1753        /* Kick recovery in case any bits were set */
1754        set_bit(MD_RECOVERY_NEEDED, &bitmap->mddev->recovery);
1755
1756        mddev->thread->timeout = mddev->bitmap_info.daemon_sleep;
1757        md_wakeup_thread(mddev->thread);
1758
1759        bitmap_update_sb(bitmap);
1760
1761        if (test_bit(BITMAP_WRITE_ERROR, &bitmap->flags))
1762                err = -EIO;
1763out:
1764        return err;
1765}
1766EXPORT_SYMBOL_GPL(bitmap_load);
1767
1768void bitmap_status(struct seq_file *seq, struct bitmap *bitmap)
1769{
1770        unsigned long chunk_kb;
1771        struct bitmap_counts *counts;
1772
1773        if (!bitmap)
1774                return;
1775
1776        counts = &bitmap->counts;
1777
1778        chunk_kb = bitmap->mddev->bitmap_info.chunksize >> 10;
1779        seq_printf(seq, "bitmap: %lu/%lu pages [%luKB], "
1780                   "%lu%s chunk",
1781                   counts->pages - counts->missing_pages,
1782                   counts->pages,
1783                   (counts->pages - counts->missing_pages)
1784                   << (PAGE_SHIFT - 10),
1785                   chunk_kb ? chunk_kb : bitmap->mddev->bitmap_info.chunksize,
1786                   chunk_kb ? "KB" : "B");
1787        if (bitmap->storage.file) {
1788                seq_printf(seq, ", file: ");
1789                seq_path(seq, &bitmap->storage.file->f_path, " \t\n");
1790        }
1791
1792        seq_printf(seq, "\n");
1793}
1794
1795int bitmap_resize(struct bitmap *bitmap, sector_t blocks,
1796                  int chunksize, int init)
1797{
1798        /* If chunk_size is 0, choose an appropriate chunk size.
1799         * Then possibly allocate new storage space.
1800         * Then quiesce, copy bits, replace bitmap, and re-start
1801         *
1802         * This function is called both to set up the initial bitmap
1803         * and to resize the bitmap while the array is active.
1804         * If this happens as a result of the array being resized,
1805         * chunksize will be zero, and we need to choose a suitable
1806         * chunksize, otherwise we use what we are given.
1807         */
1808        struct bitmap_storage store;
1809        struct bitmap_counts old_counts;
1810        unsigned long chunks;
1811        sector_t block;
1812        sector_t old_blocks, new_blocks;
1813        int chunkshift;
1814        int ret = 0;
1815        long pages;
1816        struct bitmap_page *new_bp;
1817
1818        if (chunksize == 0) {
1819                /* If there is enough space, leave the chunk size unchanged,
1820                 * else increase by factor of two until there is enough space.
1821                 */
1822                long bytes;
1823                long space = bitmap->mddev->bitmap_info.space;
1824
1825                if (space == 0) {
1826                        /* We don't know how much space there is, so limit
1827                         * to current size - in sectors.
1828                         */
1829                        bytes = DIV_ROUND_UP(bitmap->counts.chunks, 8);
1830                        if (!bitmap->mddev->bitmap_info.external)
1831                                bytes += sizeof(bitmap_super_t);
1832                        space = DIV_ROUND_UP(bytes, 512);
1833                        bitmap->mddev->bitmap_info.space = space;
1834                }
1835                chunkshift = bitmap->counts.chunkshift;
1836                chunkshift--;
1837                do {
1838                        /* 'chunkshift' is shift from block size to chunk size */
1839                        chunkshift++;
1840                        chunks = DIV_ROUND_UP_SECTOR_T(blocks, 1 << chunkshift);
1841                        bytes = DIV_ROUND_UP(chunks, 8);
1842                        if (!bitmap->mddev->bitmap_info.external)
1843                                bytes += sizeof(bitmap_super_t);
1844                } while (bytes > (space << 9));
1845        } else
1846                chunkshift = ffz(~chunksize) - BITMAP_BLOCK_SHIFT;
1847
1848        chunks = DIV_ROUND_UP_SECTOR_T(blocks, 1 << chunkshift);
1849        memset(&store, 0, sizeof(store));
1850        if (bitmap->mddev->bitmap_info.offset || bitmap->mddev->bitmap_info.file)
1851                ret = bitmap_storage_alloc(&store, chunks,
1852                                           !bitmap->mddev->bitmap_info.external);
1853        if (ret)
1854                goto err;
1855
1856        pages = DIV_ROUND_UP(chunks, PAGE_COUNTER_RATIO);
1857
1858        new_bp = kzalloc(pages * sizeof(*new_bp), GFP_KERNEL);
1859        ret = -ENOMEM;
1860        if (!new_bp) {
1861                bitmap_file_unmap(&store);
1862                goto err;
1863        }
1864
1865        if (!init)
1866                bitmap->mddev->pers->quiesce(bitmap->mddev, 1);
1867
1868        store.file = bitmap->storage.file;
1869        bitmap->storage.file = NULL;
1870
1871        if (store.sb_page && bitmap->storage.sb_page)
1872                memcpy(page_address(store.sb_page),
1873                       page_address(bitmap->storage.sb_page),
1874                       sizeof(bitmap_super_t));
1875        bitmap_file_unmap(&bitmap->storage);
1876        bitmap->storage = store;
1877
1878        old_counts = bitmap->counts;
1879        bitmap->counts.bp = new_bp;
1880        bitmap->counts.pages = pages;
1881        bitmap->counts.missing_pages = pages;
1882        bitmap->counts.chunkshift = chunkshift;
1883        bitmap->counts.chunks = chunks;
1884        bitmap->mddev->bitmap_info.chunksize = 1 << (chunkshift +
1885                                                     BITMAP_BLOCK_SHIFT);
1886
1887        blocks = min(old_counts.chunks << old_counts.chunkshift,
1888                     chunks << chunkshift);
1889
1890        spin_lock_irq(&bitmap->counts.lock);
1891        for (block = 0; block < blocks; ) {
1892                bitmap_counter_t *bmc_old, *bmc_new;
1893                int set;
1894
1895                bmc_old = bitmap_get_counter(&old_counts, block,
1896                                             &old_blocks, 0);
1897                set = bmc_old && NEEDED(*bmc_old);
1898
1899                if (set) {
1900                        bmc_new = bitmap_get_counter(&bitmap->counts, block,
1901                                                     &new_blocks, 1);
1902                        if (*bmc_new == 0) {
1903                                /* need to set on-disk bits too. */
1904                                sector_t end = block + new_blocks;
1905                                sector_t start = block >> chunkshift;
1906                                start <<= chunkshift;
1907                                while (start < end) {
1908                                        bitmap_file_set_bit(bitmap, block);
1909                                        start += 1 << chunkshift;
1910                                }
1911                                *bmc_new = 2;
1912                                bitmap_count_page(&bitmap->counts,
1913                                                  block, 1);
1914                                bitmap_set_pending(&bitmap->counts,
1915                                                   block);
1916                        }
1917                        *bmc_new |= NEEDED_MASK;
1918                        if (new_blocks < old_blocks)
1919                                old_blocks = new_blocks;
1920                }
1921                block += old_blocks;
1922        }
1923
1924        if (!init) {
1925                int i;
1926                while (block < (chunks << chunkshift)) {
1927                        bitmap_counter_t *bmc;
1928                        bmc = bitmap_get_counter(&bitmap->counts, block,
1929                                                 &new_blocks, 1);
1930                        if (bmc) {
1931                                /* new space.  It needs to be resynced, so
1932                                 * we set NEEDED_MASK.
1933                                 */
1934                                if (*bmc == 0) {
1935                                        *bmc = NEEDED_MASK | 2;
1936                                        bitmap_count_page(&bitmap->counts,
1937                                                          block, 1);
1938                                        bitmap_set_pending(&bitmap->counts,
1939                                                           block);
1940                                }
1941                        }
1942                        block += new_blocks;
1943                }
1944                for (i = 0; i < bitmap->storage.file_pages; i++)
1945                        set_page_attr(bitmap, i, BITMAP_PAGE_DIRTY);
1946        }
1947        spin_unlock_irq(&bitmap->counts.lock);
1948
1949        if (!init) {
1950                bitmap_unplug(bitmap);
1951                bitmap->mddev->pers->quiesce(bitmap->mddev, 0);
1952        }
1953        ret = 0;
1954err:
1955        return ret;
1956}
1957EXPORT_SYMBOL_GPL(bitmap_resize);
1958
1959static ssize_t
1960location_show(struct mddev *mddev, char *page)
1961{
1962        ssize_t len;
1963        if (mddev->bitmap_info.file)
1964                len = sprintf(page, "file");
1965        else if (mddev->bitmap_info.offset)
1966                len = sprintf(page, "%+lld", (long long)mddev->bitmap_info.offset);
1967        else
1968                len = sprintf(page, "none");
1969        len += sprintf(page+len, "\n");
1970        return len;
1971}
1972
1973static ssize_t
1974location_store(struct mddev *mddev, const char *buf, size_t len)
1975{
1976
1977        if (mddev->pers) {
1978                if (!mddev->pers->quiesce)
1979                        return -EBUSY;
1980                if (mddev->recovery || mddev->sync_thread)
1981                        return -EBUSY;
1982        }
1983
1984        if (mddev->bitmap || mddev->bitmap_info.file ||
1985            mddev->bitmap_info.offset) {
1986                /* bitmap already configured.  Only option is to clear it */
1987                if (strncmp(buf, "none", 4) != 0)
1988                        return -EBUSY;
1989                if (mddev->pers) {
1990                        mddev->pers->quiesce(mddev, 1);
1991                        bitmap_destroy(mddev);
1992                        mddev->pers->quiesce(mddev, 0);
1993                }
1994                mddev->bitmap_info.offset = 0;
1995                if (mddev->bitmap_info.file) {
1996                        struct file *f = mddev->bitmap_info.file;
1997                        mddev->bitmap_info.file = NULL;
1998                        restore_bitmap_write_access(f);
1999                        fput(f);
2000                }
2001        } else {
2002                /* No bitmap, OK to set a location */
2003                long long offset;
2004                if (strncmp(buf, "none", 4) == 0)
2005                        /* nothing to be done */;
2006                else if (strncmp(buf, "file:", 5) == 0) {
2007                        /* Not supported yet */
2008                        return -EINVAL;
2009                } else {
2010                        int rv;
2011                        if (buf[0] == '+')
2012                                rv = strict_strtoll(buf+1, 10, &offset);
2013                        else
2014                                rv = strict_strtoll(buf, 10, &offset);
2015                        if (rv)
2016                                return rv;
2017                        if (offset == 0)
2018                                return -EINVAL;
2019                        if (mddev->bitmap_info.external == 0 &&
2020                            mddev->major_version == 0 &&
2021                            offset != mddev->bitmap_info.default_offset)
2022                                return -EINVAL;
2023                        mddev->bitmap_info.offset = offset;
2024                        if (mddev->pers) {
2025                                mddev->pers->quiesce(mddev, 1);
2026                                rv = bitmap_create(mddev);
2027                                if (!rv)
2028                                        rv = bitmap_load(mddev);
2029                                if (rv) {
2030                                        bitmap_destroy(mddev);
2031                                        mddev->bitmap_info.offset = 0;
2032                                }
2033                                mddev->pers->quiesce(mddev, 0);
2034                                if (rv)
2035                                        return rv;
2036                        }
2037                }
2038        }
2039        if (!mddev->external) {
2040                /* Ensure new bitmap info is stored in
2041                 * metadata promptly.
2042                 */
2043                set_bit(MD_CHANGE_DEVS, &mddev->flags);
2044                md_wakeup_thread(mddev->thread);
2045        }
2046        return len;
2047}
2048
2049static struct md_sysfs_entry bitmap_location =
2050__ATTR(location, S_IRUGO|S_IWUSR, location_show, location_store);
2051
2052/* 'bitmap/space' is the space available at 'location' for the
2053 * bitmap.  This allows the kernel to know when it is safe to
2054 * resize the bitmap to match a resized array.
2055 */
2056static ssize_t
2057space_show(struct mddev *mddev, char *page)
2058{
2059        return sprintf(page, "%lu\n", mddev->bitmap_info.space);
2060}
2061
2062static ssize_t
2063space_store(struct mddev *mddev, const char *buf, size_t len)
2064{
2065        unsigned long sectors;
2066        int rv;
2067
2068        rv = kstrtoul(buf, 10, &sectors);
2069        if (rv)
2070                return rv;
2071
2072        if (sectors == 0)
2073                return -EINVAL;
2074
2075        if (mddev->bitmap &&
2076            sectors < (mddev->bitmap->storage.bytes + 511) >> 9)
2077                return -EFBIG; /* Bitmap is too big for this small space */
2078
2079        /* could make sure it isn't too big, but that isn't really
2080         * needed - user-space should be careful.
2081         */
2082        mddev->bitmap_info.space = sectors;
2083        return len;
2084}
2085
2086static struct md_sysfs_entry bitmap_space =
2087__ATTR(space, S_IRUGO|S_IWUSR, space_show, space_store);
2088
2089static ssize_t
2090timeout_show(struct mddev *mddev, char *page)
2091{
2092        ssize_t len;
2093        unsigned long secs = mddev->bitmap_info.daemon_sleep / HZ;
2094        unsigned long jifs = mddev->bitmap_info.daemon_sleep % HZ;
2095
2096        len = sprintf(page, "%lu", secs);
2097        if (jifs)
2098                len += sprintf(page+len, ".%03u", jiffies_to_msecs(jifs));
2099        len += sprintf(page+len, "\n");
2100        return len;
2101}
2102
2103static ssize_t
2104timeout_store(struct mddev *mddev, const char *buf, size_t len)
2105{
2106        /* timeout can be set at any time */
2107        unsigned long timeout;
2108        int rv = strict_strtoul_scaled(buf, &timeout, 4);
2109        if (rv)
2110                return rv;
2111
2112        /* just to make sure we don't overflow... */
2113        if (timeout >= LONG_MAX / HZ)
2114                return -EINVAL;
2115
2116        timeout = timeout * HZ / 10000;
2117
2118        if (timeout >= MAX_SCHEDULE_TIMEOUT)
2119                timeout = MAX_SCHEDULE_TIMEOUT-1;
2120        if (timeout < 1)
2121                timeout = 1;
2122        mddev->bitmap_info.daemon_sleep = timeout;
2123        if (mddev->thread) {
2124                /* if thread->timeout is MAX_SCHEDULE_TIMEOUT, then
2125                 * the bitmap is all clean and we don't need to
2126                 * adjust the timeout right now
2127                 */
2128                if (mddev->thread->timeout < MAX_SCHEDULE_TIMEOUT) {
2129                        mddev->thread->timeout = timeout;
2130                        md_wakeup_thread(mddev->thread);
2131                }
2132        }
2133        return len;
2134}
2135
2136static struct md_sysfs_entry bitmap_timeout =
2137__ATTR(time_base, S_IRUGO|S_IWUSR, timeout_show, timeout_store);
2138
2139static ssize_t
2140backlog_show(struct mddev *mddev, char *page)
2141{
2142        return sprintf(page, "%lu\n", mddev->bitmap_info.max_write_behind);
2143}
2144
2145static ssize_t
2146backlog_store(struct mddev *mddev, const char *buf, size_t len)
2147{
2148        unsigned long backlog;
2149        int rv = strict_strtoul(buf, 10, &backlog);
2150        if (rv)
2151                return rv;
2152        if (backlog > COUNTER_MAX)
2153                return -EINVAL;
2154        mddev->bitmap_info.max_write_behind = backlog;
2155        return len;
2156}
2157
2158static struct md_sysfs_entry bitmap_backlog =
2159__ATTR(backlog, S_IRUGO|S_IWUSR, backlog_show, backlog_store);
2160
2161static ssize_t
2162chunksize_show(struct mddev *mddev, char *page)
2163{
2164        return sprintf(page, "%lu\n", mddev->bitmap_info.chunksize);
2165}
2166
2167static ssize_t
2168chunksize_store(struct mddev *mddev, const char *buf, size_t len)
2169{
2170        /* Can only be changed when no bitmap is active */
2171        int rv;
2172        unsigned long csize;
2173        if (mddev->bitmap)
2174                return -EBUSY;
2175        rv = strict_strtoul(buf, 10, &csize);
2176        if (rv)
2177                return rv;
2178        if (csize < 512 ||
2179            !is_power_of_2(csize))
2180                return -EINVAL;
2181        mddev->bitmap_info.chunksize = csize;
2182        return len;
2183}
2184
2185static struct md_sysfs_entry bitmap_chunksize =
2186__ATTR(chunksize, S_IRUGO|S_IWUSR, chunksize_show, chunksize_store);
2187
2188static ssize_t metadata_show(struct mddev *mddev, char *page)
2189{
2190        return sprintf(page, "%s\n", (mddev->bitmap_info.external
2191                                      ? "external" : "internal"));
2192}
2193
2194static ssize_t metadata_store(struct mddev *mddev, const char *buf, size_t len)
2195{
2196        if (mddev->bitmap ||
2197            mddev->bitmap_info.file ||
2198            mddev->bitmap_info.offset)
2199                return -EBUSY;
2200        if (strncmp(buf, "external", 8) == 0)
2201                mddev->bitmap_info.external = 1;
2202        else if (strncmp(buf, "internal", 8) == 0)
2203                mddev->bitmap_info.external = 0;
2204        else
2205                return -EINVAL;
2206        return len;
2207}
2208
2209static struct md_sysfs_entry bitmap_metadata =
2210__ATTR(metadata, S_IRUGO|S_IWUSR, metadata_show, metadata_store);
2211
2212static ssize_t can_clear_show(struct mddev *mddev, char *page)
2213{
2214        int len;
2215        if (mddev->bitmap)
2216                len = sprintf(page, "%s\n", (mddev->bitmap->need_sync ?
2217                                             "false" : "true"));
2218        else
2219                len = sprintf(page, "\n");
2220        return len;
2221}
2222
2223static ssize_t can_clear_store(struct mddev *mddev, const char *buf, size_t len)
2224{
2225        if (mddev->bitmap == NULL)
2226                return -ENOENT;
2227        if (strncmp(buf, "false", 5) == 0)
2228                mddev->bitmap->need_sync = 1;
2229        else if (strncmp(buf, "true", 4) == 0) {
2230                if (mddev->degraded)
2231                        return -EBUSY;
2232                mddev->bitmap->need_sync = 0;
2233        } else
2234                return -EINVAL;
2235        return len;
2236}
2237
2238static struct md_sysfs_entry bitmap_can_clear =
2239__ATTR(can_clear, S_IRUGO|S_IWUSR, can_clear_show, can_clear_store);
2240
2241static ssize_t
2242behind_writes_used_show(struct mddev *mddev, char *page)
2243{
2244        if (mddev->bitmap == NULL)
2245                return sprintf(page, "0\n");
2246        return sprintf(page, "%lu\n",
2247                       mddev->bitmap->behind_writes_used);
2248}
2249
2250static ssize_t
2251behind_writes_used_reset(struct mddev *mddev, const char *buf, size_t len)
2252{
2253        if (mddev->bitmap)
2254                mddev->bitmap->behind_writes_used = 0;
2255        return len;
2256}
2257
2258static struct md_sysfs_entry max_backlog_used =
2259__ATTR(max_backlog_used, S_IRUGO | S_IWUSR,
2260       behind_writes_used_show, behind_writes_used_reset);
2261
2262static struct attribute *md_bitmap_attrs[] = {
2263        &bitmap_location.attr,
2264        &bitmap_space.attr,
2265        &bitmap_timeout.attr,
2266        &bitmap_backlog.attr,
2267        &bitmap_chunksize.attr,
2268        &bitmap_metadata.attr,
2269        &bitmap_can_clear.attr,
2270        &max_backlog_used.attr,
2271        NULL
2272};
2273struct attribute_group md_bitmap_group = {
2274        .name = "bitmap",
2275        .attrs = md_bitmap_attrs,
2276};
2277
2278
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