Btrfs: add ioctl to wait for qgroup rescan completion

btrfs_qgroup_wait_for_completion waits until the currently running qgroup
operation completes. It returns immediately when no rescan process is in
progress. This is useful to automate things around the rescan process (e.g.
testing).

Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 0f81d67cdc8d..1e0dda1feefe 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3937,6 +3937,16 @@ static long btrfs_ioctl_quota_rescan_status(struct file *file, void __user *arg)
         return ret;
 }
 
+static long btrfs_ioctl_quota_rescan_wait(struct file *file, void __user *arg)
+{
+        struct btrfs_root *root = BTRFS_I(fdentry(file)->d_inode)->root;
+
+        if (!capable(CAP_SYS_ADMIN))
+                return -EPERM;
+
+        return btrfs_qgroup_wait_for_completion(root->fs_info);
+}
+
 static long btrfs_ioctl_set_received_subvol(struct file *file,
                                             void __user *arg)
 {
@@ -4179,6 +4189,8 @@ long btrfs_ioctl(struct file *file, unsigned int
                 return btrfs_ioctl_quota_rescan(file, argp);
         case BTRFS_IOC_QUOTA_RESCAN_STATUS:
                 return btrfs_ioctl_quota_rescan_status(file, argp);
+        case BTRFS_IOC_QUOTA_RESCAN_WAIT:
+                return btrfs_ioctl_quota_rescan_wait(file, argp);
         case BTRFS_IOC_DEV_REPLACE:
                 return btrfs_ioctl_dev_replace(root, argp);
         case BTRFS_IOC_GET_FSLABEL: