[PATCH 3.10 57/78] btrfs: call mnt_drop_write after interrupted subvol deletion

From: Greg Kroah-Hartman
Date: Wed Dec 18 2013 - 16:58:05 EST


3.10-stable review patch. If anyone has any objections, please let me know.

------------------

From: David Sterba <dsterba@xxxxxxx>

commit e43f998e47bae27e37e159915625e8d4b130153b upstream.

If btrfs_ioctl_snap_destroy blocks on the mutex and the process is
killed, mnt_write count is unbalanced and leads to unmountable
filesystem.

Signed-off-by: David Sterba <dsterba@xxxxxxx>
Signed-off-by: Chris Mason <clm@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
fs/btrfs/ioctl.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2093,7 +2093,7 @@ static noinline int btrfs_ioctl_snap_des

err = mutex_lock_killable_nested(&dir->i_mutex, I_MUTEX_PARENT);
if (err == -EINTR)
- goto out;
+ goto out_drop_write;
dentry = lookup_one_len(vol_args->name, parent, namelen);
if (IS_ERR(dentry)) {
err = PTR_ERR(dentry);
@@ -2235,6 +2235,7 @@ out_dput:
dput(dentry);
out_unlock_dir:
mutex_unlock(&dir->i_mutex);
+out_drop_write:
mnt_drop_write_file(file);
out:
kfree(vol_args);


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