btrfs: wake up transaction thread from SYNC_FS ioctl

commit 2fad4e83e12591eb3bd213875b9edc2d18e93383 upstream.

The transaction thread may want to do more work, namely it pokes the
cleaner ktread that will start processing uncleaned subvols.

This can be triggered by user via the 'btrfs fi sync' command, otherwise
there was a delay up to 30 seconds before the cleaner started to clean
old snapshots.

Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index a6d8efa46bfe50129b54ef11e4a854adad3b56ac..752a0e62acbe396c90003d8e51405082911ec456 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -4750,6 +4750,12 @@ long btrfs_ioctl(struct file *file, unsigned int
                if (ret)
                        return ret;
                ret = btrfs_sync_fs(file->f_dentry->d_sb, 1);
+               /*
+                * The transaction thread may want to do more work,
+                * namely it pokes the cleaner ktread that will start
+                * processing uncleaned subvols.
+                */
+               wake_up_process(root->fs_info->transaction_kthread);
                return ret;
        }
        case BTRFS_IOC_START_SYNC: