btrfs: tree-checker: introduce checks for FREE_SPACE_BITMAP

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Introduce checks for FREE_SPACE_BITMAP item, which include:

- Key alignment check
  Same as FREE_SPACE_EXTENT, the objectid is the logical bytenr of the
  free space, and offset is the length of the free space, so both
  should be aligned to the fs block size.

- Non-zero range check
  A zero key->offset would describe an empty bitmap, which is invalid.

- Item size check
  The item must hold exactly DIV_ROUND_UP(key->offset >> sectorsize_bits,
  BITS_PER_BYTE) bytes.  A mismatch indicates a truncated or otherwise
  corrupt bitmap item; without this check, the bitmap loading path would
  walk past the end of the leaf and trigger a NULL dereference in
  assert_eb_folio_uptodate().

Signed-off-by: ZhengYuan Huang <gality369@gmail.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

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ZhengYuan Huang 2026-03-11 08:26:10 +10:30 • committed by David Sterba

parent b4a1246298

commit 94e445085c

1 changed files with 43 additions and 0 deletions

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fs/btrfs/tree-checker.c

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