From: Filipe Manana fdmanana@suse.com
commit 60d9f50308e5df19bc18c2fefab0eba4a843900a upstream.
While logging an inode we follow its ancestors and for each one we mark it as logged in the current transaction, even if we have not logged it. As a consequence if we change an attribute of an ancestor, such as the UID or GID for example, and then explicitly fsync it, we end up not logging the inode at all despite returning success to user space, which results in the attribute being lost if a power failure happens after the fsync.
Sample reproducer:
$ mkfs.btrfs -f /dev/sdb $ mount /dev/sdb /mnt
$ mkdir /mnt/dir $ chown 6007:6007 /mnt/dir
$ sync
$ chown 9003:9003 /mnt/dir $ touch /mnt/dir/file $ xfs_io -c fsync /mnt/dir/file
# fsync our directory after fsync'ing the new file, should persist the # new values for the uid and gid. $ xfs_io -c fsync /mnt/dir
<power failure>
$ mount /dev/sdb /mnt $ stat -c %u:%g /mnt/dir 6007:6007
--> should be 9003:9003, the uid and gid were not persisted, despite the explicit fsync on the directory prior to the power failure
Fix this by not updating the logged_trans field of ancestor inodes when logging an inode, since we have not logged them. Let only future calls to btrfs_log_inode() to mark inodes as logged.
This could be triggered by my recent fsync fuzz tester for fstests, for which an fstests patch exists titled "fstests: generic, fsync fuzz tester with fsstress".
Fixes: 12fcfd22fe5b ("Btrfs: tree logging unlink/rename fixes") CC: stable@vger.kernel.org # 4.4+ Signed-off-by: Filipe Manana fdmanana@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/btrfs/tree-log.c | 12 ------------ 1 file changed, 12 deletions(-)
--- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -5469,7 +5469,6 @@ static noinline int check_parent_dirs_fo { int ret = 0; struct dentry *old_parent = NULL; - struct btrfs_inode *orig_inode = inode;
/* * for regular files, if its inode is already on disk, we don't @@ -5489,16 +5488,6 @@ static noinline int check_parent_dirs_fo }
while (1) { - /* - * If we are logging a directory then we start with our inode, - * not our parent's inode, so we need to skip setting the - * logged_trans so that further down in the log code we don't - * think this inode has already been logged. - */ - if (inode != orig_inode) - inode->logged_trans = trans->transid; - smp_mb(); - if (btrfs_must_commit_transaction(trans, inode)) { ret = 1; break; @@ -6227,7 +6216,6 @@ void btrfs_record_unlink_dir(struct btrf * if this directory was already logged any new * names for this file/dir will get recorded */ - smp_mb(); if (dir->logged_trans == trans->transid) return;