[PATCH] rbd: don't destroy ceph_opts in rbd_add()

[PATCH] rbd: don't destroy ceph_opts in rbd_add()

[Alex Elder]

(Note: this patch and the two I'm about to re-post are available
in the "review/wip-4559" branch of the ceph-client git repository.)



Whether rbd_client_create() successfully creates a new client or
not, it takes responsibility for getting the ceph_opts structure
it's passed destroyed.  If successful, the structure becomes
associated with the created client; if not, rbd_client_create()
will destroy it.

Previously, rbd_get_client() would call ceph_destroy_options()
if rbd_get_client() failed, and that meant it got called twice.
That led freeing various pointers more than once, which is never a
good idea.

This resolves:
    http://tracker.ceph.com/issues/4559

Reported-by: Dan van der Ster <dan@vanderster.com>
Signed-off-by: Alex Elder <elder@inktank.com>
---
 drivers/block/rbd.c |   10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index e8d4693..ade30dd 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -521,8 +521,8 @@ static const struct block_device_operations
rbd_bd_ops = {
 };

 /*
- * Initialize an rbd client instance.
- * We own *ceph_opts.
+ * Initialize an rbd client instance.  Success or not, this function
+ * consumes ceph_opts.
  */
 static struct rbd_client *rbd_client_create(struct ceph_options *ceph_opts)
 {
@@ -677,7 +677,8 @@ static int parse_rbd_opts_token(char *c, void *private)

 /*
  * Get a ceph client with specific addr and configuration, if one does
- * not exist create it.
+ * not exist create it.  Either way, ceph_opts is consumed by this
+ * function.
  */
 static struct rbd_client *rbd_get_client(struct ceph_options *ceph_opts)
 {
@@ -4994,7 +4995,6 @@ static ssize_t rbd_add(struct bus_type *bus,
 		rc = PTR_ERR(rbdc);
 		goto err_out_args;
 	}
-	ceph_opts = NULL;	/* rbd_dev client now owns this */

 	/* pick the pool */
 	osdc = &rbdc->client->osdc;
@@ -5038,8 +5038,6 @@ err_out_rbd_dev:
 err_out_client:
 	rbd_put_client(rbdc);
 err_out_args:
-	if (ceph_opts)
-		ceph_destroy_options(ceph_opts);
 	kfree(rbd_opts);
 	rbd_spec_put(spec);
 err_out_module:
-- 
1.7.9.5

Re: [PATCH] rbd: don't destroy ceph_opts in rbd_add()

[Josh Durgin]

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

On 05/16/2013 02:29 PM, Alex Elder wrote:
> (Note: this patch and the two I'm about to re-post are available
> in the "review/wip-4559" branch of the ceph-client git repository.)
>
>
>
> Whether rbd_client_create() successfully creates a new client or
> not, it takes responsibility for getting the ceph_opts structure
> it's passed destroyed.  If successful, the structure becomes
> associated with the created client; if not, rbd_client_create()
> will destroy it.
>
> Previously, rbd_get_client() would call ceph_destroy_options()
> if rbd_get_client() failed, and that meant it got called twice.
> That led freeing various pointers more than once, which is never a
> good idea.
>
> This resolves:
>      http://tracker.ceph.com/issues/4559
>
> Reported-by: Dan van der Ster <dan@vanderster.com>
> Signed-off-by: Alex Elder <elder@inktank.com>
> ---
>   drivers/block/rbd.c |   10 ++++------
>   1 file changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
> index e8d4693..ade30dd 100644
> --- a/drivers/block/rbd.c
> +++ b/drivers/block/rbd.c
> @@ -521,8 +521,8 @@ static const struct block_device_operations
> rbd_bd_ops = {
>   };
>
>   /*
> - * Initialize an rbd client instance.
> - * We own *ceph_opts.
> + * Initialize an rbd client instance.  Success or not, this function
> + * consumes ceph_opts.
>    */
>   static struct rbd_client *rbd_client_create(struct ceph_options *ceph_opts)
>   {
> @@ -677,7 +677,8 @@ static int parse_rbd_opts_token(char *c, void *private)
>
>   /*
>    * Get a ceph client with specific addr and configuration, if one does
> - * not exist create it.
> + * not exist create it.  Either way, ceph_opts is consumed by this
> + * function.
>    */
>   static struct rbd_client *rbd_get_client(struct ceph_options *ceph_opts)
>   {
> @@ -4994,7 +4995,6 @@ static ssize_t rbd_add(struct bus_type *bus,
>   		rc = PTR_ERR(rbdc);
>   		goto err_out_args;
>   	}
> -	ceph_opts = NULL;	/* rbd_dev client now owns this */
>
>   	/* pick the pool */
>   	osdc = &rbdc->client->osdc;
> @@ -5038,8 +5038,6 @@ err_out_rbd_dev:
>   err_out_client:
>   	rbd_put_client(rbdc);
>   err_out_args:
> -	if (ceph_opts)
> -		ceph_destroy_options(ceph_opts);
>   	kfree(rbd_opts);
>   	rbd_spec_put(spec);
>   err_out_module:
>