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

[Chris Mason <clm@fb.com>]

On 06/23/2016 08:54 AM, Anand Jain wrote:
> 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 */
>

This should do it,I'll check with the xfstest I was able to reliably get 
errors on.

Thanks!

-chris