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Btrfs: detect corruption when non-root leaf has zero item

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Right now we treat leaf which has zero item as a valid one
because we could have an empty tree, that is, a root that is
also a leaf without any item, however, in the same case but
when the leaf is not a root, we can end up with hitting the
BUG_ON(1) in btrfs_extend_item() called by
setup_inline_extent_backref().

This makes us check the situation as a corruption if leaf is
not its own root.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
This commit is contained in:
Liu Bo 2016-08-23 15:22:58 -07:00 committed by Chris Mason
parent 053ab70f06
commit 1ba98d086f
1 changed files with 22 additions and 1 deletions
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23
fs/btrfs/disk-io.c
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@ -560,8 +560,29 @@ static noinline int check_leaf(struct btrfs_root *root,
u32 nritems = btrfs_header_nritems(leaf);
int slot;
if (nritems == 0)
if (nritems == 0) {
struct btrfs_root *check_root;
key.objectid = btrfs_header_owner(leaf);
key.type = BTRFS_ROOT_ITEM_KEY;
key.offset = (u64)-1;
check_root = btrfs_get_fs_root(root->fs_info, &key, false);
/*
* The only reason we also check NULL here is that during
* open_ctree() some roots has not yet been set up.
*/
if (!IS_ERR_OR_NULL(check_root)) {
/* if leaf is the root, then it's fine */
if (leaf->start !=
btrfs_root_bytenr(&check_root->root_item)) {
CORRUPT("non-root leaf's nritems is 0",
leaf, root, 0);
return -EIO;
}
}
return 0;
}
/* Check the 0 item */
if (btrfs_item_offset_nr(leaf, 0) + btrfs_item_size_nr(leaf, 0) !=