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btrfs: tree-checker: add remap-tree checks to check_block_group_item()

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Add some write-time checks for block group items relating to the remap
tree.

Here we're checking:

* That the REMAPPED or METADATA_REMAP flags aren't set unless the
  REMAP_TREE incompat flag is also set
* That `remap_bytes` isn't more than the size of the block group
* That `identity_remap_count` isn't more than the number of sectors in
  the block group

Signed-off-by: Mark Harmstone <mark@harmstone.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Mark Harmstone 2026-03-25 12:53:43 +00:00 • committed by David Sterba
commit b753612be0
1 changed files with 41 additions and 0 deletions
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41
fs/btrfs/tree-checker.c
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@ -777,6 +777,47 @@ static int check_block_group_item(struct extent_buffer *leaf,
BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA);
return -EUCLEAN;
}
if (unlikely(!btrfs_fs_incompat(fs_info, REMAP_TREE) &&
type == BTRFS_BLOCK_GROUP_METADATA_REMAP)) {
block_group_err(leaf, slot,
"invalid type, METADATA_REMAP set but REMAP_TREE incompat flag not set");
return -EUCLEAN;
}
if (unlikely(!btrfs_fs_incompat(fs_info, REMAP_TREE) &&
flags & BTRFS_BLOCK_GROUP_REMAPPED)) {
block_group_err(leaf, slot,
"invalid flags, REMAPPED set but REMAP_TREE incompat flag not set");
return -EUCLEAN;
}
if (item_size == sizeof(struct btrfs_block_group_item_v2)) {
struct btrfs_block_group_item_v2 *bgi2;
u64 remap_bytes;
u32 identity_remap_count;
bgi2 = btrfs_item_ptr(leaf, slot, struct btrfs_block_group_item_v2);
remap_bytes = btrfs_block_group_v2_remap_bytes(leaf, bgi2);
if (unlikely(remap_bytes > key->offset)) {
block_group_err(leaf, slot,
"invalid remap_bytes, have %llu expect [0, %llu]",
remap_bytes, key->offset);
return -EUCLEAN;
}
identity_remap_count = btrfs_block_group_v2_identity_remap_count(leaf, bgi2);
if (unlikely((u64)identity_remap_count >
key->offset >> fs_info->sectorsize_bits)) {
block_group_err(leaf, slot,
"invalid identity_remap_count, have %u expect [0, %llu]",
identity_remap_count,
key->offset >> fs_info->sectorsize_bits);
return -EUCLEAN;
}
}
return 0;
}