[PATCH v3 2/2] btrfs: make sure device is synced before return

[Anand Jain <anand.jain@oracle.com>]

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>
---
 v2: Also to make sure bdev_closing is set it needs rcu_barrier(),
     restored rcu_barrier().
 v3: Removed the complicated timed-wait on blkdev_put code,
     but make synced and invalidated before umount is returned.
     So sorry that I have to change the title of this patch
     as well (was: btrfs: wait for bdev put).

 fs/btrfs/volumes.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 604daf315669..f741ade130a4 100644
--- 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 */
-- 
2.7.0