3.12-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
@@ -2130,7 +2130,7 @@ 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);
@@ -2293,6 +2293,7 @@ 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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