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ext4: avoid allocating blocks from corrupted group in ext4_mb_try_best_found()

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Determine if the group block bitmap is corrupted before using ac_b_ex in
ext4_mb_try_best_found() to avoid allocating blocks from a group with a
corrupted block bitmap in the following concurrency and making the
situation worse.

ext4_mb_regular_allocator
  ext4_lock_group(sb, group)
  ext4_mb_good_group
   // check if the group bbitmap is corrupted
  ext4_mb_complex_scan_group
   // Scan group gets ac_b_ex but doesn't use it
  ext4_unlock_group(sb, group)
                           ext4_mark_group_bitmap_corrupted(group)
                           // The block bitmap was corrupted during
                           // the group unlock gap.
  ext4_mb_try_best_found
    ext4_lock_group(ac->ac_sb, group)
    ext4_mb_use_best_found
      mb_mark_used
      // Allocating blocks in block bitmap corrupted group

Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240104142040.2835097-7-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Baokun Li 2024-01-04 22:20:38 +08:00 committed by Theodore Ts'o
parent 993bf0f4c3
commit 4530b3660d
1 changed files with 4 additions and 0 deletions
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4
fs/ext4/mballoc.c
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@ -2299,6 +2299,9 @@ void ext4_mb_try_best_found(struct ext4_allocation_context *ac,
return;
ext4_lock_group(ac->ac_sb, group);
if (unlikely(EXT4_MB_GRP_BBITMAP_CORRUPT(e4b->bd_info)))
goto out;
max = mb_find_extent(e4b, ex.fe_start, ex.fe_len, &ex);
if (max > 0) {
@ -2306,6 +2309,7 @@ void ext4_mb_try_best_found(struct ext4_allocation_context *ac,
ext4_mb_use_best_found(ac, e4b);
}
out:
ext4_unlock_group(ac->ac_sb, group);
ext4_mb_unload_buddy(e4b);
}