btrfs: tree-checker: Try to detect missing INODE_ITEM

For the following items, key->objectid is inode number:
- DIR_ITEM
- DIR_INDEX
- XATTR_ITEM
- EXTENT_DATA
- INODE_REF

So in the subvolume tree, such items must have its previous item share the
same objectid, e.g.:

 (257 INODE_ITEM 0)
 (257 DIR_INDEX xxx)
 (257 DIR_ITEM xxx)
 (258 INODE_ITEM 0)
 (258 INODE_REF 0)
 (258 XATTR_ITEM 0)
 (258 EXTENT_DATA 0)

But if we have the following sequence, then there is definitely
something wrong, normally some INODE_ITEM is missing, like:

 (257 INODE_ITEM 0)
 (257 DIR_INDEX xxx)
 (257 DIR_ITEM xxx)
 (258 XATTR_ITEM 0)  <<< objecitd suddenly changed to 258
 (258 EXTENT_DATA 0)

So just by checking the previous key for above inode based key types, we
can detect a missing inode item.

For INODE_REF key type, the check will be added along with INODE_REF
checker.

Reviewed-by: Nikolay Borisov <nborisov@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>

diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
index 076d5b8014fb3091483e93c234cc6284521f74e3..5aca82e67309d4b84af5b2c2d590fbf867e0a48a 100644 (file)
--- a/fs/btrfs/tree-checker.c
+++ b/fs/btrfs/tree-checker.c
@@ -141,6 +141,20 @@ static int check_extent_data_item(struct extent_buffer *leaf,
                return -EUCLEAN;
        }
 
+       /*
+        * Previous key must have the same key->objectid (ino).
+        * It can be XATTR_ITEM, INODE_ITEM or just another EXTENT_DATA.
+        * But if objectids mismatch, it means we have a missing
+        * INODE_ITEM.
+        */
+       if (slot > 0 && is_fstree(btrfs_header_owner(leaf)) &&
+           prev_key->objectid != key->objectid) {
+               file_extent_err(leaf, slot,
+               "invalid previous key objectid, have %llu expect %llu",
+                               prev_key->objectid, key->objectid);
+               return -EUCLEAN;
+       }
+
        fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
 
        if (btrfs_file_extent_type(leaf, fi) > BTRFS_FILE_EXTENT_TYPES) {
@@ -299,13 +313,22 @@ static void dir_item_err(const struct extent_buffer *eb, int slot,
 }
 
 static int check_dir_item(struct extent_buffer *leaf,
-                         struct btrfs_key *key, int slot)
+                         struct btrfs_key *key, struct btrfs_key *prev_key,
+                         int slot)
 {
        struct btrfs_fs_info *fs_info = leaf->fs_info;
        struct btrfs_dir_item *di;
        u32 item_size = btrfs_item_size_nr(leaf, slot);
        u32 cur = 0;
 
+       /* Same check as in check_extent_data_item() */
+       if (slot > 0 && is_fstree(btrfs_header_owner(leaf)) &&
+           prev_key->objectid != key->objectid) {
+               dir_item_err(leaf, slot,
+               "invalid previous key objectid, have %llu expect %llu",
+                            prev_key->objectid, key->objectid);
+               return -EUCLEAN;
+       }
        di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
        while (cur < item_size) {
                u32 name_len;
@@ -1244,7 +1267,7 @@ static int check_leaf_item(struct extent_buffer *leaf,
        case BTRFS_DIR_ITEM_KEY:
        case BTRFS_DIR_INDEX_KEY:
        case BTRFS_XATTR_ITEM_KEY:
-               ret = check_dir_item(leaf, key, slot);
+               ret = check_dir_item(leaf, key, prev_key, slot);
                break;
        case BTRFS_BLOCK_GROUP_ITEM_KEY:
                ret = check_block_group_item(leaf, key, slot);