rbd: record mapped size

Add the size of the mapped image to the set of mapping-specific
fields in an rbd_device, and use it when setting the capacity of the
disk.

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 dff621060432..4377a8302fc3 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -151,6 +151,7 @@ struct rbd_snap {
 struct rbd_mapping {
         char                    *snap_name;
         u64                     snap_id;
+        u64                     size;
         bool                    snap_exists;
         bool                    read_only;
 };
@@ -643,7 +644,7 @@ static int snap_by_name(struct rbd_image_header *header, const char *snap_name,
         return -ENOENT;
 }
 
-static int rbd_header_set_snap(struct rbd_device *rbd_dev, u64 *size)
+static int rbd_header_set_snap(struct rbd_device *rbd_dev)
 {
         int ret;
 
@@ -652,19 +653,16 @@ static int rbd_header_set_snap(struct rbd_device *rbd_dev, u64 *size)
         if (!memcmp(rbd_dev->mapping.snap_name, RBD_SNAP_HEAD_NAME,
                     sizeof (RBD_SNAP_HEAD_NAME))) {
                 rbd_dev->mapping.snap_id = CEPH_NOSNAP;
+                rbd_dev->mapping.size = rbd_dev->header.image_size;
                 rbd_dev->mapping.snap_exists = false;
                 rbd_dev->mapping.read_only = rbd_dev->rbd_opts.read_only;
-                if (size)
-                        *size = rbd_dev->header.image_size;
         } else {
-                u64 snap_id = 0;
-
                 ret = snap_by_name(&rbd_dev->header,
                                         rbd_dev->mapping.snap_name,
-                                        &snap_id, size);
+                                        &rbd_dev->mapping.snap_id,
+                                        &rbd_dev->mapping.size);
                 if (ret < 0)
                         goto done;
-                rbd_dev->mapping.snap_id = snap_id;
                 rbd_dev->mapping.snap_exists = true;
                 rbd_dev->mapping.read_only = true;
         }
@@ -1830,8 +1828,12 @@ static int __rbd_refresh_header(struct rbd_device *rbd_dev, u64 *hver)
         if (rbd_dev->mapping.snap_id == CEPH_NOSNAP) {
                 sector_t size = (sector_t) h.image_size / SECTOR_SIZE;
 
-                dout("setting size to %llu sectors", (unsigned long long) size);
-                set_capacity(rbd_dev->disk, size);
+                if (size != (sector_t) rbd_dev->mapping.size) {
+                        dout("setting size to %llu sectors",
+                                (unsigned long long) size);
+                        rbd_dev->mapping.size = (u64) size;
+                        set_capacity(rbd_dev->disk, size);
+                }
         }
 
         /* rbd_dev->header.object_prefix shouldn't change */
@@ -1875,7 +1877,6 @@ static int rbd_init_disk(struct rbd_device *rbd_dev)
         struct request_queue *q;
         int rc;
         u64 segment_size;
-        u64 total_size = 0;
 
         /* contact OSD, request size info about the object being mapped */
         rc = rbd_read_header(rbd_dev, &rbd_dev->header);
@@ -1887,7 +1888,7 @@ static int rbd_init_disk(struct rbd_device *rbd_dev)
         if (rc)
                 return rc;
 
-        rc = rbd_header_set_snap(rbd_dev, &total_size);
+        rc = rbd_header_set_snap(rbd_dev);
         if (rc)
                 return rc;
 
@@ -1928,11 +1929,11 @@ static int rbd_init_disk(struct rbd_device *rbd_dev)
         rbd_dev->disk = disk;
 
         /* finally, announce the disk to the world */
-        set_capacity(disk, total_size / SECTOR_SIZE);
+        set_capacity(disk, (sector_t) rbd_dev->mapping.size / SECTOR_SIZE);
         add_disk(disk);
 
         pr_info("%s: added with size 0x%llx\n",
-                disk->disk_name, (unsigned long long)total_size);
+                disk->disk_name, (unsigned long long) rbd_dev->mapping.size);
         return 0;
 
 out_disk: