4.4-stable review patch. If anyone has any objections, please let me know.
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From: Liu Bo bo.li.liu@oracle.com
commit ef85b25e982b5bba1530b936e283ef129f02ab9d upstream.
This can only happen with CONFIG_BTRFS_FS_CHECK_INTEGRITY=y.
Commit 1ba98d0 ("Btrfs: detect corruption when non-root leaf has zero item") assumes that a leaf is its root when leaf->bytenr == btrfs_root_bytenr(root), however, we should not use btrfs_root_bytenr(root) since it's mainly got updated during committing transaction. So the check can fail when doing COW on this leaf while it is a root.
This changes to use "if (leaf == btrfs_root_node(root))" instead, just like how we check whether leaf is a root in __btrfs_cow_block().
Fixes: 1ba98d086fe3 (Btrfs: detect corruption when non-root leaf has zero item) Reported-by: Jeff Mahoney jeffm@suse.com Signed-off-by: Liu Bo bo.li.liu@oracle.com Reviewed-by: Filipe Manana fdmanana@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Ben Hutchings ben.hutchings@codethink.co.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/btrfs/disk-io.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)
--- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -548,13 +548,17 @@ static noinline int check_leaf(struct bt * open_ctree() some roots has not yet been set up. */ if (!IS_ERR_OR_NULL(check_root)) { + struct extent_buffer *eb; + + eb = btrfs_root_node(check_root); /* if leaf is the root, then it's fine */ - if (leaf->start != - btrfs_root_bytenr(&check_root->root_item)) { + if (leaf != eb) { CORRUPT("non-root leaf's nritems is 0", - leaf, root, 0); + leaf, check_root, 0); + free_extent_buffer(eb); return -EIO; } + free_extent_buffer(eb); } return 0; }