rbd: set the mapping size and features later

Defer setting the size and features fields of a mapped image until
after the Linux disk structure is set up.  Set the capacity of the
disk after that.

Rearrange the definition of rbd_image_header, separating the fields
that are set only once from those that can be updated.

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

1 files changed, 14 insertions, 13 deletions

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index b5cac7931ffc..a05b6e5dc362 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -100,21 +100,20 @@
  * block device image metadata (in-memory version)
  */
 struct rbd_image_header {
-        /* These four fields never change for a given rbd image */
+        /* These six fields never change for a given rbd image */
         char *object_prefix;
-        u64 features;
         __u8 obj_order;
         __u8 crypt_type;
         __u8 comp_type;
+        u64 stripe_unit;
+        u64 stripe_count;
+        u64 features;           /* Might be changeable someday? */
 
         /* The remaining fields need to be updated occasionally */
         u64 image_size;
         struct ceph_snap_context *snapc;
-        char *snap_names;
-        u64 *snap_sizes;
-
-        u64 stripe_unit;
-        u64 stripe_count;
+        char *snap_names;       /* format 1 only */
+        u64 *snap_sizes;        /* format 1 only */
 };
 
 /*
@@ -4637,10 +4636,6 @@ static int rbd_dev_device_setup(struct rbd_device *rbd_dev)
 {
         int ret;
 
-        ret = rbd_dev_mapping_set(rbd_dev);
-        if (ret)
-                return ret;
-
         /* generate unique id: find highest unique id, add one */
         rbd_dev_id_get(rbd_dev);
 
@@ -4662,13 +4657,17 @@ static int rbd_dev_device_setup(struct rbd_device *rbd_dev)
         if (ret)
                 goto err_out_blkdev;
 
-        ret = rbd_bus_add_dev(rbd_dev);
+        ret = rbd_dev_mapping_set(rbd_dev);
         if (ret)
                 goto err_out_disk;
+        set_capacity(rbd_dev->disk, rbd_dev->mapping.size / SECTOR_SIZE);
+
+        ret = rbd_bus_add_dev(rbd_dev);
+        if (ret)
+                goto err_out_mapping;
 
         /* Everything's ready.  Announce the disk to the world. */
 
-        set_capacity(rbd_dev->disk, rbd_dev->mapping.size / SECTOR_SIZE);
         set_bit(RBD_DEV_FLAG_EXISTS, &rbd_dev->flags);
         add_disk(rbd_dev->disk);
 
@@ -4677,6 +4676,8 @@ static int rbd_dev_device_setup(struct rbd_device *rbd_dev)
 
         return ret;
 
+err_out_mapping:
+        rbd_dev_mapping_clear(rbd_dev);
 err_out_disk:
         rbd_free_disk(rbd_dev);
 err_out_blkdev: