rbd: use rbd_segment_name_free() instead of kfree()

Free memory allocated using kmem_cache_zalloc using kmem_cache_free
rather than kfree. The helper rbd_segment_name_free does the job here.
Its position is shifted above the calling function.

The Coccinelle semantic patch that detects this change is as follows:

// <smpl>
@@
expression x,E,c;
@@

 x = \(kmem_cache_alloc\|kmem_cache_zalloc\|kmem_cache_alloc_node\)(c,...)
 ... when != x = E
     when != &x
?-kfree(x)
+kmem_cache_free(c,x)
// </smpl>
Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Ilya Dryomov <ilya.dryomov@inktank.com>

drivers/block/rbd.c

@@ -1139,6 +1139,13 @@ static void rbd_dev_mapping_clear(struct rbd_device *rbd_dev)
 	rbd_dev->mapping.features = 0;
 }
 
+static void rbd_segment_name_free(const char *name)
+{
+	/* The explicit cast here is needed to drop the const qualifier */
+
+	kmem_cache_free(rbd_segment_name_cache, (void *)name);
+}
+
 static const char *rbd_segment_name(struct rbd_device *rbd_dev, u64 offset)
 {
 	char *name;
@@ -1158,20 +1165,13 @@ static const char *rbd_segment_name(struct rbd_device *rbd_dev, u64 offset)
 	if (ret < 0 || ret > CEPH_MAX_OID_NAME_LEN) {
 		pr_err("error formatting segment name for #%llu (%d)\n",
 			segment, ret);
-		kfree(name);
+		rbd_segment_name_free(name);
 		name = NULL;
 	}
 
 	return name;
 }
 
-static void rbd_segment_name_free(const char *name)
-{
-	/* The explicit cast here is needed to drop the const qualifier */
-
-	kmem_cache_free(rbd_segment_name_cache, (void *)name);
-}
-
 static u64 rbd_segment_offset(struct rbd_device *rbd_dev, u64 offset)
 {
 	u64 segment_size = (u64) 1 << rbd_dev->header.obj_order;