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btrfs: add strict extent map alignment checks 

Currently we do not check the alignment of extent_map structure.

The reasons are the inode and extent-map tests use unaligned values
for start offsets and lengths.

Thankfully those legacy problems are properly addressed by previous
patches, now we can finally put the alignment checks into
validate_extent_map().

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2026-01-22 09:38:00 +10:30 committed by David Sterba
parent 385c65f827
commit 71e545d4e3
1 changed files with 12 additions and 0 deletions
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12
fs/btrfs/extent_map.c
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@ -319,8 +319,15 @@ static void dump_extent_map(struct btrfs_fs_info *fs_info, const char *prefix,
/* Internal sanity checks for btrfs debug builds. */
static void validate_extent_map(struct btrfs_fs_info *fs_info, struct extent_map *em)
{
const u32 blocksize = fs_info->sectorsize;
if (!IS_ENABLED(CONFIG_BTRFS_DEBUG))
return;
if (!IS_ALIGNED(em->start, blocksize) ||
!IS_ALIGNED(em->len, blocksize))
dump_extent_map(fs_info, "unaligned start offset or length members", em);
if (em->disk_bytenr < EXTENT_MAP_LAST_BYTE) {
if (em->disk_num_bytes == 0)
dump_extent_map(fs_info, "zero disk_num_bytes", em);
@ -334,6 +341,11 @@ static void validate_extent_map(struct btrfs_fs_info *fs_info, struct extent_map
dump_extent_map(fs_info,
"ram_bytes mismatch with disk_num_bytes for non-compressed em",
em);
if (!IS_ALIGNED(em->disk_bytenr, blocksize) ||
!IS_ALIGNED(em->disk_num_bytes, blocksize) ||
!IS_ALIGNED(em->offset, blocksize) ||
!IS_ALIGNED(em->ram_bytes, blocksize))
dump_extent_map(fs_info, "unaligned members", em);
} else if (em->offset) {
dump_extent_map(fs_info, "non-zero offset for hole/inline", em);
}