Alex Elder <elder@xxxxxxxxxxx> wrote: >If more than one rbd image has the same ceph cluster configuration >(same options, same set of monitors, same keys) they normally share >a single rbd client. > >When an image is getting mapped, rbd looks to see if an existing >client can be used, and creates a new one if not. > >The lookup and creation are not done under a common lock though, so >mapping two images concurrently could lead to duplicate clients >getting set up needlessly. This isn't a major problem, but it's >wasteful and different from what's intended. > >This patch fixes that by using the control mutex to protect >both the lookup and (if needed) creation of the client. It >was previously used just when creating. > >This resolves: > http://tracker.ceph.com/issues/3094 > >Signed-off-by: Alex Elder <elder@xxxxxxxxxxx> >--- > drivers/block/rbd.c | 7 +++---- > 1 file changed, 3 insertions(+), 4 deletions(-) > >diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c >index aec2438..d255541 100644 >--- a/drivers/block/rbd.c >+++ b/drivers/block/rbd.c >@@ -522,7 +522,7 @@ static const struct block_device_operations >rbd_bd_ops = { > > /* > * Initialize an rbd client instance. Success or not, this function >- * consumes ceph_opts. >+ * consumes ceph_opts. Caller holds ctl_mutex > */ >static struct rbd_client *rbd_client_create(struct ceph_options >*ceph_opts) > { >@@ -537,8 +537,6 @@ static struct rbd_client *rbd_client_create(struct >ceph_options *ceph_opts) > kref_init(&rbdc->kref); > INIT_LIST_HEAD(&rbdc->node); > >- mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING); >- > rbdc->client = ceph_create_client(ceph_opts, rbdc, 0, 0); > if (IS_ERR(rbdc->client)) > goto out_mutex; >@@ -552,7 +550,6 @@ static struct rbd_client *rbd_client_create(struct >ceph_options *ceph_opts) > list_add_tail(&rbdc->node, &rbd_client_list); > spin_unlock(&rbd_client_list_lock); > >- mutex_unlock(&ctl_mutex); > dout("%s: rbdc %p\n", __func__, rbdc); > > return rbdc; >@@ -684,11 +681,13 @@ static struct rbd_client *rbd_get_client(struct >ceph_options *ceph_opts) > { > struct rbd_client *rbdc; > >+ mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING); > rbdc = rbd_client_find(ceph_opts); > if (rbdc) /* using an existing client */ > ceph_destroy_options(ceph_opts); > else > rbdc = rbd_client_create(ceph_opts); >+ mutex_unlock(&ctl_mutex); > > return rbdc; > } Reviewed-by: Josh Durgin <josh.durgin@xxxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
