diff mbox

Btrfs: fix empty symlink after creating symlink and fsync parent dir

Message ID 1461558331-32199-1-git-send-email-fdmanana@kernel.org (mailing list archive)
State Accepted
Headers show

Commit Message

Filipe Manana April 25, 2016, 4:25 a.m. UTC 
From: Filipe Manana <fdmanana@suse.com>

If we create a symlink, fsync its parent directory, crash/power fail and
mount the filesystem, we end up with an empty symlink, which not only is
useless it's also not allowed in linux (the man page symlink(2) is well
explicit about that).  So we just need to make sure to fully log an inode
if it's a symlink, to ensure its inline extent gets logged, ensuring the
same behaviour as ext3, ext4, xfs, reiserfs, f2fs, nilfs2, etc.

Example reproducer:

  $ mkfs.btrfs -f /dev/sdb
  $ mount /dev/sdb /mnt
  $ mkdir /mnt/testdir
  $ sync
  $ ln -s /mnt/foo /mnt/testdir/bar
  $ xfs_io -c fsync /mnt/testdir
  <power fail>
  $ mount /dev/sdb /mnt
  $ readlink /mnt/testdir/bar
  <empty string>

A test case for fstests follows soon.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
---
 fs/btrfs/tree-log.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff mbox

Patch

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 4709932..a24a0ba 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -5158,7 +5158,7 @@  process_leaf:
 			}
 
 			ctx->log_new_dentries = false;
-			if (type == BTRFS_FT_DIR)
+			if (type == BTRFS_FT_DIR || type == BTRFS_FT_SYMLINK)
 				log_mode = LOG_INODE_ALL;
 			btrfs_release_path(path);
 			ret = btrfs_log_inode(trans, root, di_inode,