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btrfs: tree-checker: validate dref root and objectid

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[CORRUPTION]
There is a bug report that btrfs flips RO due to a corruption in the
extent tree, the involved dumps looks like this:

 	item 188 key (402811572224 168 4096) itemoff 14598 itemsize 79
 		extent refs 3 gen 3678544 flags 1
 		ref#0: extent data backref root 13835058055282163977 objectid 281473384125923 offset 81432576 count 1
 		ref#1: shared data backref parent 1947073626112 count 1
 		ref#2: shared data backref parent 1156030103552 count 1
 BTRFS critical (device vdc1: state EA): unable to find ref byte nr 402811572224 parent 0 root 265 owner 28703026 offset 81432576 slot 189
 BTRFS error (device vdc1: state EA): failed to run delayed ref for logical 402811572224 num_bytes 4096 type 178 action 2 ref_mod 1: -2

[CAUSE]
The corrupted entry is ref#0 of item 188.
The root number 13835058055282163977 is beyond the upper limit for root
items (the current limit is 1 << 48), and the objectid also looks
suspicious.

Only the offset and count is correct.

[ENHANCEMENT]
Although it's still unknown why we have such many bytes corrupted
randomly, we can still enhance the tree-checker for data backrefs by:

- Validate the root value
  For now there should only be 3 types of roots can have data backref:
  * subvolume trees
  * data reloc trees
  * root tree
    Only for v1 space cache

- validate the objectid value
  The objectid should be a valid inode number.

Hopefully we can catch such problem in the future with the new checkers.

Reported-by: Kai Krakow <hurikhan77@gmail.com>
Link: https://lore.kernel.org/linux-btrfs/CAMthOuPjg5RDT-G_LXeBBUUtzt3cq=JywF+D1_h+JYxe=WKp-Q@mail.gmail.com/#t
Reviewed-by: Filipe Manana <fdmanana@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>
This commit is contained in:
Qu Wenruo 2024-07-15 16:07:07 +09:30 committed by David Sterba
parent c3ece6b7ff
commit f333a3c7e8
1 changed files with 47 additions and 0 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

47
fs/btrfs/tree-checker.c
View file

@ -1289,6 +1289,19 @@ static void extent_err(const struct extent_buffer *eb, int slot,
va_end(args);
}
static bool is_valid_dref_root(u64 rootid)
{
/*
* The following tree root objectids are allowed to have a data backref:
* - subvolume trees
* - data reloc tree
* - tree root
* For v1 space cache
*/
return is_fstree(rootid) || rootid == BTRFS_DATA_RELOC_TREE_OBJECTID ||
rootid == BTRFS_ROOT_TREE_OBJECTID;
}
static int check_extent_item(struct extent_buffer *leaf,
struct btrfs_key *key, int slot,
struct btrfs_key *prev_key)
@ -1441,6 +1454,8 @@ static int check_extent_item(struct extent_buffer *leaf,
struct btrfs_extent_data_ref *dref;
struct btrfs_shared_data_ref *sref;
u64 seq;
u64 dref_root;
u64 dref_objectid;
u64 dref_offset;
u64 inline_offset;
u8 inline_type;
@ -1484,11 +1499,26 @@ static int check_extent_item(struct extent_buffer *leaf,
*/
case BTRFS_EXTENT_DATA_REF_KEY:
dref = (struct btrfs_extent_data_ref *)(&iref->offset);
dref_root = btrfs_extent_data_ref_root(leaf, dref);
dref_objectid = btrfs_extent_data_ref_objectid(leaf, dref);
dref_offset = btrfs_extent_data_ref_offset(leaf, dref);
seq = hash_extent_data_ref(
btrfs_extent_data_ref_root(leaf, dref),
btrfs_extent_data_ref_objectid(leaf, dref),
btrfs_extent_data_ref_offset(leaf, dref));
if (unlikely(!is_valid_dref_root(dref_root))) {
extent_err(leaf, slot,
"invalid data ref root value %llu",
dref_root);
return -EUCLEAN;
}
if (unlikely(dref_objectid < BTRFS_FIRST_FREE_OBJECTID ||
dref_objectid > BTRFS_LAST_FREE_OBJECTID)) {
extent_err(leaf, slot,
"invalid data ref objectid value %llu",
dref_root);
return -EUCLEAN;
}
if (unlikely(!IS_ALIGNED(dref_offset,
fs_info->sectorsize))) {
extent_err(leaf, slot,
@ -1627,6 +1657,8 @@ static int check_extent_data_ref(struct extent_buffer *leaf,
return -EUCLEAN;
}
for (; ptr < end; ptr += sizeof(*dref)) {
u64 root;
u64 objectid;
u64 offset;
/*
@ -1634,7 +1666,22 @@ static int check_extent_data_ref(struct extent_buffer *leaf,
* overflow from the leaf due to hash collisions.
*/
dref = (struct btrfs_extent_data_ref *)ptr;
root = btrfs_extent_data_ref_root(leaf, dref);
objectid = btrfs_extent_data_ref_objectid(leaf, dref);
offset = btrfs_extent_data_ref_offset(leaf, dref);
if (unlikely(!is_valid_dref_root(root))) {
extent_err(leaf, slot,
"invalid extent data backref root value %llu",
root);
return -EUCLEAN;
}
if (unlikely(objectid < BTRFS_FIRST_FREE_OBJECTID ||
objectid > BTRFS_LAST_FREE_OBJECTID)) {
extent_err(leaf, slot,
"invalid extent data backref objectid value %llu",
root);
return -EUCLEAN;
}
if (unlikely(!IS_ALIGNED(offset, leaf->fs_info->sectorsize))) {
extent_err(leaf, slot,
"invalid extent data backref offset, have %llu expect aligned to %u",