ceph: use ceph_create_snap_context()

Now that we have a library routine to create snap contexts, use it.

This is part of:
    http://tracker.ceph.com/issues/4857Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

drivers/block/rbd.c

@@ -672,35 +672,6 @@ static void rbd_client_release(struct kref *kref)
 	kfree(rbdc);
 }
 
-/* Caller has to fill in snapc->seq and snapc->snaps[0..snap_count-1] */
-
-static struct ceph_snap_context *rbd_snap_context_create(u32 snap_count)
-{
-	struct ceph_snap_context *snapc;
-	size_t size;
-
-	size = sizeof (struct ceph_snap_context);
-	size += snap_count * sizeof (snapc->snaps[0]);
-	snapc = kzalloc(size, GFP_KERNEL);
-	if (!snapc)
-		return NULL;
-
-	atomic_set(&snapc->nref, 1);
-	snapc->num_snaps = snap_count;
-
-	return snapc;
-}
-
-static inline void rbd_snap_context_get(struct ceph_snap_context *snapc)
-{
-	(void)ceph_get_snap_context(snapc);
-}
-
-static inline void rbd_snap_context_put(struct ceph_snap_context *snapc)
-{
-	ceph_put_snap_context(snapc);
-}
-
 /*
  * Drop reference to ceph client node. If it's not referenced anymore, release
  * it.
@@ -820,7 +791,7 @@ static int rbd_header_from_disk(struct rbd_image_header *header,
 
 	header->image_size = le64_to_cpu(ondisk->image_size);
 
-	header->snapc = rbd_snap_context_create(snap_count);
+	header->snapc = ceph_create_snap_context(snap_count, GFP_KERNEL);
 	if (!header->snapc)
 		goto out_err;
 	header->snapc->seq = le64_to_cpu(ondisk->snap_seq);
@@ -1753,7 +1724,7 @@ static struct rbd_img_request *rbd_img_request_create(
 
 	if (write_request) {
 		down_read(&rbd_dev->header_rwsem);
-		rbd_snap_context_get(rbd_dev->header.snapc);
+		ceph_get_snap_context(rbd_dev->header.snapc);
 		up_read(&rbd_dev->header_rwsem);
 	}
 
@@ -1805,7 +1776,7 @@ static void rbd_img_request_destroy(struct kref *kref)
 	rbd_assert(img_request->obj_request_count == 0);
 
 	if (img_request_write_test(img_request))
-		rbd_snap_context_put(img_request->snapc);
+		ceph_put_snap_context(img_request->snapc);
 
 	if (img_request_child_test(img_request))
 		rbd_obj_request_put(img_request->obj_request);
@@ -3071,7 +3042,7 @@ static int rbd_dev_v1_refresh(struct rbd_device *rbd_dev, u64 *hver)
 	kfree(rbd_dev->header.snap_sizes);
 	kfree(rbd_dev->header.snap_names);
 	/* osd requests may still refer to snapc */
-	rbd_snap_context_put(rbd_dev->header.snapc);
+	ceph_put_snap_context(rbd_dev->header.snapc);
 
 	if (hver)
 		*hver = h.obj_version;
@@ -3914,7 +3885,7 @@ static int rbd_dev_v2_snap_context(struct rbd_device *rbd_dev, u64 *ver)
 		goto out;
 	ret = 0;
 
-	snapc = rbd_snap_context_create(snap_count);
+	snapc = ceph_create_snap_context(snap_count, GFP_KERNEL);
 	if (!snapc) {
 		ret = -ENOMEM;
 		goto out;
@@ -4590,7 +4561,7 @@ static void rbd_dev_unprobe(struct rbd_device *rbd_dev)
 	/* Free dynamic fields from the header, then zero it out */
 
 	header = &rbd_dev->header;
-	rbd_snap_context_put(header->snapc);
+	ceph_put_snap_context(header->snapc);
 	kfree(header->snap_sizes);
 	kfree(header->snap_names);
 	kfree(header->object_prefix);

fs/ceph/snap.c

@@ -332,10 +332,9 @@ static int build_snap_context(struct ceph_snap_realm *realm)
 	err = -ENOMEM;
 	if (num > (SIZE_MAX - sizeof(*snapc)) / sizeof(u64))
 		goto fail;
-	snapc = kzalloc(sizeof(*snapc) + num*sizeof(u64), GFP_NOFS);
+	snapc = ceph_create_snap_context(num, GFP_NOFS);
 	if (!snapc)
 		goto fail;
-	atomic_set(&snapc->nref, 1);
 
 	/* build (reverse sorted) snap vector */
 	num = 0;