rbd: use sizeof (object) instead of sizeof (type)

Fix a few spots in rbd_header_from_disk() to use sizeof (object)
rather than sizeof (type).  Use a local variable to record sizes
to shorten some lines and improve readability.

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

1 files changed, 15 insertions, 13 deletions

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index e5eaa70e8826..2a94f8e81f67 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -494,17 +494,21 @@ static int rbd_header_from_disk(struct rbd_image_header *header,
                                  u32 allocated_snaps)
 {
         u32 snap_count;
+        size_t size;
 
         if (!rbd_dev_ondisk_valid(ondisk))
                 return -ENXIO;
 
         snap_count = le32_to_cpu(ondisk->snap_count);
-        if (snap_count > (SIZE_MAX - sizeof(struct ceph_snap_context))
-                                 / sizeof (u64))
+
+        /* Make sure we don't overflow below */
+        size = SIZE_MAX - sizeof (struct ceph_snap_context);
+        if (snap_count > size / sizeof (header->snapc->snaps[0]))
                 return -EINVAL;
-        header->snapc = kmalloc(sizeof(struct ceph_snap_context) +
-                                snap_count * sizeof(u64),
-                                GFP_KERNEL);
+
+        size = sizeof (struct ceph_snap_context);
+        size += snap_count * sizeof (header->snapc->snaps[0]);
+        header->snapc = kmalloc(size, GFP_KERNEL);
         if (!header->snapc)
                 return -ENOMEM;
 
@@ -515,8 +519,8 @@ static int rbd_header_from_disk(struct rbd_image_header *header,
                                              GFP_KERNEL);
                 if (!header->snap_names)
                         goto err_snapc;
-                header->snap_sizes = kmalloc(snap_count * sizeof(u64),
-                                             GFP_KERNEL);
+                size = snap_count * sizeof (*header->snap_sizes);
+                header->snap_sizes = kmalloc(size, GFP_KERNEL);
                 if (!header->snap_sizes)
                         goto err_names;
         } else {
@@ -526,14 +530,12 @@ static int rbd_header_from_disk(struct rbd_image_header *header,
                 header->snap_sizes = NULL;
         }
 
-        header->object_prefix = kmalloc(sizeof (ondisk->block_name) + 1,
-                                        GFP_KERNEL);
+        size = sizeof (ondisk->block_name) + 1;
+        header->object_prefix = kmalloc(size, GFP_KERNEL);
         if (!header->object_prefix)
                 goto err_sizes;
-
-        memcpy(header->object_prefix, ondisk->block_name,
-               sizeof(ondisk->block_name));
-        header->object_prefix[sizeof (ondisk->block_name)] = '\0';
+        memcpy(header->object_prefix, ondisk->block_name, size - 1);
+        header->object_prefix[size - 1] = '\0';
 
         header->image_size = le64_to_cpu(ondisk->image_size);
         header->obj_order = ondisk->options.order;