btrfs: fall back to global reservation when removing subvolumes

I recently did some ENOSPC testing that involved filling the disk
while create and removing snapshots in a loop. During the test cycle,
I ran into an ENOSPC when trying to remove a snapshot, leaving the fs
stuck in ENOSPC even after a umount/mount cycle.

This patch allow subvolume removal to fall back onto the global
block reservation in order to succeed when it would have failed
otherwise.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 238a05545ee2..841044b80658 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -396,7 +396,7 @@ static noinline int create_subvol(struct inode *dir,
          * of create_snapshot().
          */
         ret = btrfs_subvolume_reserve_metadata(root, &block_rsv,
-                                               7, &qgroup_reserved);
+                                               7, &qgroup_reserved, false);
         if (ret)
                 return ret;
 
@@ -576,7 +576,8 @@ static int create_snapshot(struct btrfs_root *root, struct inode *dir,
          */
         ret = btrfs_subvolume_reserve_metadata(BTRFS_I(dir)->root,
                                         &pending_snapshot->block_rsv, 7,
-                                        &pending_snapshot->qgroup_reserved);
+                                        &pending_snapshot->qgroup_reserved,
+                                        false);
         if (ret)
                 goto out;
 
@@ -2174,7 +2175,7 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file,
          * ref/backref.
          */
         err = btrfs_subvolume_reserve_metadata(root, &block_rsv,
-                                               5, &qgroup_reserved);
+                                               5, &qgroup_reserved, true);
         if (err)
                 goto out_up_write;