ceph: use kref for ceph_buffer

Signed-off-by: Sage Weil <sage@newdream.net>

fs/ceph/buffer.c

@@ -9,13 +9,25 @@ struct ceph_buffer *ceph_buffer_new(gfp_t gfp)
 	b = kmalloc(sizeof(*b), gfp);
 	if (!b)
 		return NULL;
-	atomic_set(&b->nref, 1);
+	kref_init(&b->kref);
 	b->vec.iov_base = NULL;
 	b->vec.iov_len = 0;
 	b->alloc_len = 0;
 	return b;
 }
 
+void ceph_buffer_release(struct kref *kref)
+{
+	struct ceph_buffer *b = container_of(kref, struct ceph_buffer, kref);
+	if (b->vec.iov_base) {
+		if (b->is_vmalloc)
+			vfree(b->vec.iov_base);
+		else
+			kfree(b->vec.iov_base);
+	}
+	kfree(b);
+}
+
 int ceph_buffer_alloc(struct ceph_buffer *b, int len, gfp_t gfp)
 {
 	b->vec.iov_base = kmalloc(len, gfp | __GFP_NOWARN);

fs/ceph/buffer.h

 #ifndef __FS_CEPH_BUFFER_H
 #define __FS_CEPH_BUFFER_H
 
+#include <linux/kref.h>
 #include <linux/mm.h>
 #include <linux/vmalloc.h>
 #include <linux/types.h>
@@ -13,7 +14,7 @@
  * sizes.
  */
 struct ceph_buffer {
-	atomic_t nref;
+	struct kref kref;
 	struct kvec vec;
 	size_t alloc_len;
 	bool is_vmalloc;
@@ -24,21 +25,16 @@ int ceph_buffer_alloc(struct ceph_buffer *b, int len, gfp_t gfp);
 
 static inline struct ceph_buffer *ceph_buffer_get(struct ceph_buffer *b)
 {
-	atomic_inc(&b->nref);
+	kref_get(&b->kref);
 	return b;
 }
 
+void ceph_buffer_release(struct kref *kref);
+
 static inline void ceph_buffer_put(struct ceph_buffer *b)
 {
-	if (b && atomic_dec_and_test(&b->nref)) {
-		if (b->vec.iov_base) {
-			if (b->is_vmalloc)
-				vfree(b->vec.iov_base);
-			else
-				kfree(b->vec.iov_base);
-		}
-		kfree(b);
-	}
+	if (b)
+		kref_put(&b->kref, ceph_buffer_release);
 }
 
 static inline struct ceph_buffer *ceph_buffer_new_alloc(int len, gfp_t gfp)