Re: [PATCH v3 4/5] rbd: ignore unmapped snapshots that no longer exist

[Alex Elder <alex.elder@linaro.org>]

On 09/09/2013 02:17 AM, Josh Durgin wrote:
> This prevents erroring out while adding a device when a snapshot
> unrelated to the current mapping is deleted between reading the
> snapshot context and reading the snapshot names. If the mapped
> snapshot name is not found an error still occurs as usual.

This looks good.

In fact, you could even go as far as ignoring errors
altogether.  This function is determining the name associated
with a snapshot id, and doubles as an existence check.  We
need to look at the whole list to know that the snapshot
id doesn't exist, so errors along the way are just a distraction.

(But don't bother changing it, what you have is good.)

Reviewed-by: Alex Elder <elder@linaro.org>

> Signed-off-by: Josh Durgin <josh.durgin@inktank.com>
> ---
>  drivers/block/rbd.c |    9 +++++++--
>  1 files changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
> index fe5767a..226fa04 100644
> --- a/drivers/block/rbd.c
> +++ b/drivers/block/rbd.c
> @@ -4078,8 +4078,13 @@ static u64 rbd_v2_snap_id_by_name(struct rbd_device *rbd_dev, const char *name)
>  
>  		snap_id = snapc->snaps[which];
>  		snap_name = rbd_dev_v2_snap_name(rbd_dev, snap_id);
> -		if (IS_ERR(snap_name))
> -			break;
> +		if (IS_ERR(snap_name)) {
> +			/* ignore no-longer existing snapshots */
> +			if (PTR_ERR(snap_name) == -ENOENT)
> +				continue;
> +			else
> +				break;
> +		}
>  		found = !strcmp(name, snap_name);
>  		kfree(snap_name);
>  	}
>