Re: [PATCH 08/16] rbd: don't store pool name in struct rbd_dev

[Alex Elder <elder@inktank.com>]

On 07/11/2012 02:36 PM, Josh Durgin wrote:
> On 07/11/2012 07:02 AM, Alex Elder wrote:
>> An rbd device's pool name is used to specify the pool to use for an
>> rbd image when it gets mapped (via rbd_add()).  However, only the
>> pool id can be relied on to be invariant--the name of a pool can
>> change at any time.
>>
>> This means that the name of the pool is potentially stale as soon as
>> the image is mapped, so it's a bad idea to record this information.
>> So only store the pool id, not its name, in an rbd_dev.
>>
>> Here are a few specific notes about this change:
>>      - The "pool" name device attribute (/sys/bus/rbd/devices/<N>/pool)
>>        goes away.  In its place is a "pool_id" attribute that provide
>>        the numeric pool id for the rbd image.
> 
> We're using the pool name for udev to provide a predictable device name
> (/dev/rbd/poolname/imagename[@snapname]), so we probably want to keep
> the sysfs attribute. I don't think there's a good way for us to detect
> pool renames right now though, so we should document that the pool
> name reported does not reflect any potential renames.

OK.  I'll put the "pool" name entry back, but will still include the
new "pool_id" entry as well.  Do you want me to re-post after that,
or can I consider this reviewed?

					-Alex

>>      - rbd_add_parse_args() now returns a pointer to a dynamically-
>>        allocated copy of the pool name taken from the arguments.
>>      - rbd_add() has been changed to handle freeing the pool name,
>>        both in error cases and in the normal case after the pool id
>>        has been recorded.
>>
>> Signed-off-by: Alex Elder<elder@inktank.com>

. . .