rbd: set snapshot id in rbd_dev_probe_update_spec()

Set the rbd spec's snapshot id for an image getting mapped in
rbd_dev_probe_update_spec() rather than rbd_dev_set_mapping().
This is the more logical place for that to happen (even though
it means we might look up the snapshot by name twice).

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 6b1e9a9f2f726dc76cd27424284d41ddc1fdeab1..c34f8716d1d2109f20e0fa639c2b48d8382db5e0 100644 (file)
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -846,7 +846,6 @@ static int rbd_dev_set_mapping(struct rbd_device *rbd_dev)
 {
        if (!memcmp(rbd_dev->spec->snap_name, RBD_SNAP_HEAD_NAME,
                    sizeof (RBD_SNAP_HEAD_NAME))) {
-               rbd_dev->spec->snap_id = CEPH_NOSNAP;
                rbd_dev->mapping.size = rbd_dev->header.image_size;
                rbd_dev->mapping.features = rbd_dev->header.features;
        } else {
@@ -855,7 +854,6 @@ static int rbd_dev_set_mapping(struct rbd_device *rbd_dev)
                snap = snap_by_name(rbd_dev, rbd_dev->spec->snap_name);
                if (!snap)
                        return -ENOENT;
-               rbd_dev->spec->snap_id = snap->id;
                rbd_dev->mapping.size = snap->size;
                rbd_dev->mapping.features = snap->features;
                rbd_dev->mapping.read_only = true;
@@ -3760,6 +3758,10 @@ out:
  * rbd_dev_snaps_update() has completed because some of the
  * information (in particular, snapshot name) is not available
  * until then.
+ *
+ * When an image being mapped (not a parent) is probed, we have the
+ * pool name and pool id, image name and image id, and the snapshot
+ * name.  The only thing we're missing is the snapshot id.
  */
 static int rbd_dev_probe_update_spec(struct rbd_device *rbd_dev)
 {
@@ -3768,8 +3770,24 @@ static int rbd_dev_probe_update_spec(struct rbd_device *rbd_dev)
        void *reply_buf = NULL;
        int ret;
 
-       if (rbd_dev->spec->pool_name)
-               return 0;       /* Already have the names */
+       /*
+        * An image being mapped will have the pool name (etc.), but
+        * we need to look up the snapshot id.
+        */
+       if (rbd_dev->spec->pool_name) {
+               if (strcmp(rbd_dev->spec->snap_name, RBD_SNAP_HEAD_NAME)) {
+                       struct rbd_snap *snap;
+
+                       snap = snap_by_name(rbd_dev, rbd_dev->spec->snap_name);
+                       if (!snap)
+                               return -ENOENT;
+                       rbd_dev->spec->snap_id = snap->id;
+               } else {
+                       rbd_dev->spec->snap_id = CEPH_NOSNAP;
+               }
+
+               return 0;
+       }
 
        /* Look up the pool name */