rbd: preserve snapc->seq in rbd_header_set_snap()

In rbd_header_set_snap(), there is logic to make the snap context's
seq field get set to a particular snapshot id, or 0 if there is no
snapshot for the rbd image.

This seems to be an artifact of how the current snapshot id for an
rbd_dev was recorded before the rbd_dev->snap_id field began to be
used for that purpose.

There's no need to update the value of snapc->seq here any more, so
stop doing it.  Tidy up a few local variables in that function
while we're at it.

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 8a46599..ac8a83f 100644 (file)
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -588,29 +588,25 @@ static int snap_by_name(struct rbd_image_header *header, const char *snap_name,
 
 static int rbd_header_set_snap(struct rbd_device *rbd_dev, u64 *size)
 {
-       struct rbd_image_header *header = &rbd_dev->header;
-       struct ceph_snap_context *snapc = header->snapc;
-       int ret = -ENOENT;
+       int ret;
 
        down_write(&rbd_dev->header_rwsem);
 
        if (!memcmp(rbd_dev->snap_name, RBD_SNAP_HEAD_NAME,
                    sizeof (RBD_SNAP_HEAD_NAME))) {
-               if (header->total_snaps)
-                       snapc->seq = header->snap_seq;
-               else
-                       snapc->seq = 0;
                rbd_dev->snap_id = CEPH_NOSNAP;
                rbd_dev->snap_exists = false;
                rbd_dev->read_only = 0;
                if (size)
-                       *size = header->image_size;
+                       *size = rbd_dev->header.image_size;
        } else {
-               ret = snap_by_name(header, rbd_dev->snap_name,
-                                       &snapc->seq, size);
+               u64 snap_id = 0;
+
+               ret = snap_by_name(&rbd_dev->header, rbd_dev->snap_name,
+                                       &snap_id, size);
                if (ret < 0)
                        goto done;
-               rbd_dev->snap_id = snapc->seq;
+               rbd_dev->snap_id = snap_id;
                rbd_dev->snap_exists = true;
                rbd_dev->read_only = 1;
        }