Re: [PATCH 1/2] rbd: don't leak rbd_req on synchronous requests

[Josh Durgin <josh.durgin@inktank.com>]

Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

On 11/30/2012 08:04 AM, Alex Elder wrote:
> When rbd_do_request() is called it allocates and populates an
> rbd_req structure to hold information about the osd request to be
> sent.  This is done for the benefit of the callback function (in
> particular, rbd_req_cb()), which uses this in processing when
> the request completes.
>
> Synchronous requests provide no callback function, in which case
> rbd_do_request() waits for the request to complete before returning.
> This case is not handling the needed free of the rbd_req structure
> like it should, so it is getting leaked.
>
> Note however that the synchronous case has no need for the rbd_req
> structure at all.  So rather than simply freeing this structure for
> synchronous requests, just don't allocate it to begin with.
>
> Signed-off-by: Alex Elder <elder@inktank.com>
> ---
>   drivers/block/rbd.c |   48 ++++++++++++++++++++++++------------------------
>   1 file changed, 24 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
> index acdb4a6..78493e7 100644
> --- a/drivers/block/rbd.c
> +++ b/drivers/block/rbd.c
> @@ -1160,20 +1160,11 @@ static int rbd_do_request(struct request *rq,
>   					 struct ceph_msg *),
>   			  u64 *ver)
>   {
> +	struct ceph_osd_client *osdc;
>   	struct ceph_osd_request *osd_req;
> -	int ret;
> +	struct rbd_request *rbd_req = NULL;
>   	struct timespec mtime = CURRENT_TIME;
> -	struct rbd_request *rbd_req;
> -	struct ceph_osd_client *osdc;
> -
> -	rbd_req = kzalloc(sizeof(*rbd_req), GFP_NOIO);
> -	if (!rbd_req)
> -		return -ENOMEM;
> -
> -	if (coll) {
> -		rbd_req->coll = coll;
> -		rbd_req->coll_index = coll_index;
> -	}
> +	int ret;
>
>   	dout("rbd_do_request object_name=%s ofs=%llu len=%llu coll=%p[%d]\n",
>   		object_name, (unsigned long long) ofs,
> @@ -1181,10 +1172,8 @@ static int rbd_do_request(struct request *rq,
>
>   	osdc = &rbd_dev->rbd_client->client->osdc;
>   	osd_req = ceph_osdc_alloc_request(osdc, snapc, 1, false, GFP_NOIO);
> -	if (!osd_req) {
> -		ret = -ENOMEM;
> -		goto done_pages;
> -	}
> +	if (!osd_req)
> +		return -ENOMEM;
>
>   	osd_req->r_flags = flags;
>   	osd_req->r_pages = pages;
> @@ -1192,13 +1181,22 @@ static int rbd_do_request(struct request *rq,
>   		osd_req->r_bio = bio;
>   		bio_get(osd_req->r_bio);
>   	}
> -	osd_req->r_callback = rbd_cb;
>
> -	rbd_req->rq = rq;
> -	rbd_req->bio = bio;
> -	rbd_req->pages = pages;
> -	rbd_req->len = len;
> +	if (rbd_cb) {
> +		ret = -ENOMEM;
> +		rbd_req = kmalloc(sizeof(*rbd_req), GFP_NOIO);
> +		if (!rbd_req)
> +			goto done_osd_req;
> +
> +		rbd_req->rq = rq;
> +		rbd_req->bio = bio;
> +		rbd_req->pages = pages;
> +		rbd_req->len = len;
> +		rbd_req->coll = coll;
> +		rbd_req->coll_index = coll ? coll_index : 0;
> +	}
>
> +	osd_req->r_callback = rbd_cb;
>   	osd_req->r_priv = rbd_req;
>
>   	strncpy(osd_req->r_oid, object_name, sizeof(osd_req->r_oid));
> @@ -1233,10 +1231,12 @@ static int rbd_do_request(struct request *rq,
>   	return ret;
>
>   done_err:
> -	bio_chain_put(rbd_req->bio);
> -	ceph_osdc_put_request(osd_req);
> -done_pages:
> +	if (bio)
> +		bio_chain_put(osd_req->r_bio);
>   	kfree(rbd_req);
> +done_osd_req:
> +	ceph_osdc_put_request(osd_req);
> +
>   	return ret;
>   }
>