btrfs: make sure device is synced before return

An inconsistent behavior due to stale reads from the
disk was reported

  mail-archive.com/linux-btrfs@vger.kernel.org/msg54188.html

This patch will make sure devices are synced before
return in the unmount thread.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index e54b3fe92e90bc3338d075fc6695649efa343e9b..51bd3ee8e64f43c9271245d179e287a841ebbc8c 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -870,6 +870,11 @@ static void btrfs_close_one_device(struct btrfs_device *device)
        if (device->missing)
                fs_devices->missing_devices--;
 
+       if (device->bdev && device->writeable) {
+               sync_blockdev(device->bdev);
+               invalidate_bdev(device->bdev);
+       }
+
        new_device = btrfs_alloc_device(NULL, &device->devid,
                                        device->uuid);
        BUG_ON(IS_ERR(new_device)); /* -ENOMEM */