btrfs: make subvol creation/deletion killable in the early stages

The subvolume ioctls block on the parent directory mutex that can be
held by other concurrent snapshot activity for a long time. Give the
user at least some chance to get out of this situation by allowing
to send a kill signal.

Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 2c02310ff2d9..9c44d657b795 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -723,7 +723,9 @@ static noinline int btrfs_mksubvol(struct path *parent,
         struct dentry *dentry;
         int error;
 
-        mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT);
+        error = mutex_lock_killable_nested(&dir->i_mutex, I_MUTEX_PARENT);
+        if (error == -EINTR)
+                return error;
 
         dentry = lookup_one_len(name, parent->dentry, namelen);
         error = PTR_ERR(dentry);
@@ -2086,7 +2088,9 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file,
         if (err)
                 goto out;
 
-        mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT);
+        err = mutex_lock_killable_nested(&dir->i_mutex, I_MUTEX_PARENT);
+        if (err == -EINTR)
+                goto out;
         dentry = lookup_one_len(vol_args->name, parent, namelen);
         if (IS_ERR(dentry)) {
                 err = PTR_ERR(dentry);