Re: [PATCH 1/7] btrfs: restore uuid_mutex in btrfs_open_devices

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

On 06/21/2018 01:51 AM, David Sterba wrote:
> Commit 542c5908abfe84f7b4c1 ("btrfs: replace uuid_mutex by
> device_list_mutex in btrfs_open_devices") switched to device_list_mutex
> as we need that for the device list traversal, but we also need
> uuid_mutex to protect access to fs_devices::opened to be consistent with
> other users of that item.
> 
> CC: Anand Jain <anand.jain@oracle.com>
> Signed-off-by: David Sterba <dsterba@suse.com>

  I am optimize the uuid_mutex for fsids concurrency on top these set of 
patches, so.

  Reviewed-by: Anand Jain <anand.jain@oracle.com>

Thanks, Anand

> ---
>   fs/btrfs/volumes.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index e034ad9e23b4..1da162928d1a 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -1146,6 +1146,7 @@ int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
>   {
>   	int ret;
>   
> +	mutex_lock(&uuid_mutex);
>   	mutex_lock(&fs_devices->device_list_mutex);
>   	if (fs_devices->opened) {
>   		fs_devices->opened++;
> @@ -1155,6 +1156,7 @@ int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
>   		ret = open_fs_devices(fs_devices, flags, holder);
>   	}
>   	mutex_unlock(&fs_devices->device_list_mutex);
> +	mutex_unlock(&uuid_mutex);
>   
>   	return ret;
>   }
>