Btrfs: allow for canceling restriper

Implement an ioctl for canceling restriper.  Currently we wait until
relocation of the current block group is finished, in future this can be
done by triggering a commit.  Balance item is deleted and no memory
about the interrupted balance is kept.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 1afda75d5414..dfc136cc07d7 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1216,6 +1216,7 @@ struct btrfs_fs_info {
         struct mutex balance_mutex;
         atomic_t balance_running;
         atomic_t balance_pause_req;
+        atomic_t balance_cancel_req;
         struct btrfs_balance_control *balance_ctl;
         wait_queue_head_t balance_wait_q;