rbd: use rbd_warn(), not WARN_ON()

Change some calls to WARN_ON() so they use rbd_warn() instead, so we
get consistent messaging.  A few remain but they can probably just
go away eventually.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

drivers/block/rbd.c

@@ -777,7 +777,6 @@ static int rbd_header_from_disk(struct rbd_image_header *header,
 			header->snap_sizes[i] =
 				le64_to_cpu(ondisk->snaps[i].image_size);
 	} else {
-		WARN_ON(ondisk->snap_names_len);
 		header->snap_names = NULL;
 		header->snap_sizes = NULL;
 	}
@@ -2755,8 +2754,11 @@ static void rbd_request_fn(struct request_queue *q)
 		}
 
 		result = -EINVAL;
-		if (WARN_ON(offset && length > U64_MAX - offset + 1))
+		if (offset && length > U64_MAX - offset + 1) {
+			rbd_warn(rbd_dev, "bad request range (%llu~%llu)\n",
+				offset, length);
 			goto end_request;	/* Shouldn't happen */
+		}
 
 		result = -ENOMEM;
 		img_request = rbd_img_request_create(rbd_dev, offset, length,
@@ -2955,7 +2957,7 @@ rbd_dev_v1_header_read(struct rbd_device *rbd_dev, u64 *version)
 				       0, size, ondisk, version);
 		if (ret < 0)
 			goto out_err;
-		if (WARN_ON((size_t) ret < size)) {
+		if ((size_t)ret < size) {
 			ret = -ENXIO;
 			rbd_warn(rbd_dev, "short header read (want %zd got %d)",
 				size, ret);
@@ -3057,7 +3059,8 @@ static int rbd_dev_v1_refresh(struct rbd_device *rbd_dev, u64 *hver)
 	rbd_dev->header.snap_names = h.snap_names;
 	rbd_dev->header.snap_sizes = h.snap_sizes;
 	/* Free the extra copy of the object prefix */
-	WARN_ON(strcmp(rbd_dev->header.object_prefix, h.object_prefix));
+	if (strcmp(rbd_dev->header.object_prefix, h.object_prefix))
+		rbd_warn(rbd_dev, "object prefix changed (ignoring)");
 	kfree(h.object_prefix);
 
 	ret = rbd_dev_snaps_update(rbd_dev);
@@ -3627,8 +3630,11 @@ static int rbd_dev_v2_parent_info(struct rbd_device *rbd_dev)
 	/* The ceph file layout needs to fit pool id in 32 bits */
 
 	ret = -EIO;
-	if (WARN_ON(parent_spec->pool_id > (u64)U32_MAX))
+	if (parent_spec->pool_id > (u64)U32_MAX) {
+		rbd_warn(NULL, "parent pool id too large (%llu > %u)\n",
+			(unsigned long long)parent_spec->pool_id, U32_MAX);
 		goto out_err;
+	}
 
 	image_id = ceph_extract_encoded_string(&p, end, NULL, GFP_KERNEL);
 	if (IS_ERR(image_id)) {
@@ -4864,11 +4870,13 @@ static ssize_t rbd_add(struct bus_type *bus,
 	rc = ceph_pg_poolid_by_name(osdc->osdmap, spec->pool_name);
 	if (rc < 0)
 		goto err_out_client;
-	spec->pool_id = (u64) rc;
+	spec->pool_id = (u64)rc;
 
 	/* The ceph file layout needs to fit pool id in 32 bits */
 
-	if (WARN_ON(spec->pool_id > (u64) U32_MAX)) {
+	if (spec->pool_id > (u64)U32_MAX) {
+		rbd_warn(NULL, "pool id too large (%llu > %u)\n",
+				(unsigned long long)spec->pool_id, U32_MAX);
 		rc = -EIO;
 		goto err_out_client;
 	}
@@ -4902,7 +4910,7 @@ static ssize_t rbd_add(struct bus_type *bus,
 
 	dout("Error adding device %s\n", buf);
 
-	return (ssize_t) rc;
+	return (ssize_t)rc;
 }
 
 static struct rbd_device *__rbd_get_dev(unsigned long dev_id)