Re: [PATCH] Revert "Btrfs: device_list_add() should not update list when

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

   Looks good to me Chris. Thank you.


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


On 09/18/2014 11:00 PM, Chris Mason wrote:
>
> Johannes and Sam, could you please confirm this patch fixes your mount
> regression for now?  Anand, please make sure I kept the generation check
> properly.
>
> This reverts commit b96de000bc8bc9688b3a2abea4332bd57648a49f.
>
> This commit is triggering failures to mount by subvolume id in some
> configurations.  The main problem is how many different ways this
> scanning function is used, both for scanning while mounted and
> unmounted.  A proper cleanup is too big for late rcs.
>
> For now, just revert the commit and we'll put a better fix into a later
> merge window.
>
> Signed-off-by: Chris Mason <clm@fb.com>
> ---
>   fs/btrfs/volumes.c | 13 ++++++-------
>   1 file changed, 6 insertions(+), 7 deletions(-)
>
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 340a92d..2c2d6d1 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -529,12 +529,12 @@ static noinline int device_list_add(const char *path,
>   		 */
>
>   		/*
> -		 * As of now don't allow update to btrfs_fs_device through
> -		 * the btrfs dev scan cli, after FS has been mounted.
> +		 * For now, we do allow update to btrfs_fs_device through the
> +		 * btrfs dev scan cli after FS has been mounted.  We're still
> +		 * tracking a problem where systems fail mount by subvolume id
> +		 * when we reject replacement on a mounted FS.
>   		 */
> -		if (fs_devices->opened) {
> -			return -EBUSY;
> -		} else {
> +		if (!fs_devices->opened && found_transid < device->generation) {
>   			/*
>   			 * That is if the FS is _not_ mounted and if you
>   			 * are here, that means there is more than one
> @@ -542,8 +542,7 @@ static noinline int device_list_add(const char *path,
>   			 * with larger generation number or the last-in if
>   			 * generation are equal.
>   			 */
> -			if (found_transid < device->generation)
> -				return -EEXIST;
> +			return -EEXIST;
>   		}
>
>   		name = rcu_string_strdup(path, GFP_NOFS);
>