From: Qu Wenruo wqu@suse.com
[ Upstream commit f333a3c7e8323499aa65038e77fe8f3199d4e283 ]
[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... 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 Signed-off-by: Sasha Levin sashal@kernel.org --- fs/btrfs/tree-checker.c | 47 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+)
diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c index 5d6cfa618dc47..f14825f3d4e82 100644 --- a/fs/btrfs/tree-checker.c +++ b/fs/btrfs/tree-checker.c @@ -1265,6 +1265,19 @@ 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) @@ -1417,6 +1430,8 @@ 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; @@ -1460,11 +1475,26 @@ 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, @@ -1600,6 +1630,8 @@ static int check_extent_data_ref(struct extent_buffer *leaf, return -EUCLEAN; } for (; ptr < end; ptr += sizeof(*dref)) { + u64 root; + u64 objectid; u64 offset;
/* @@ -1607,7 +1639,22 @@ 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",