libceph, rbd: add error handling for osd_req_op_cls_init()

Add proper error handling for osd_req_op_cls_init() to replace
BUG_ON statement when failing from memory allocation.
Signed-off-by: Chengguang Xu <cgxu519@gmx.com>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

drivers/block/rbd.c

@@ -2339,6 +2339,7 @@ static bool is_zero_bvecs(struct bio_vec *bvecs, u32 bytes)
 static int rbd_obj_issue_copyup(struct rbd_obj_request *obj_req, u32 bytes)
 {
 	unsigned int num_osd_ops = obj_req->osd_req->r_num_ops;
+	int ret;
 
 	dout("%s obj_req %p bytes %u\n", __func__, obj_req, bytes);
 	rbd_assert(obj_req->osd_req->r_ops[0].op == CEPH_OSD_OP_STAT);
@@ -2353,6 +2354,11 @@ static int rbd_obj_issue_copyup(struct rbd_obj_request *obj_req, u32 bytes)
 	if (!obj_req->osd_req)
 		return -ENOMEM;
 
+	ret = osd_req_op_cls_init(obj_req->osd_req, 0, CEPH_OSD_OP_CALL, "rbd",
+				  "copyup");
+	if (ret)
+		return ret;
+
 	/*
 	 * Only send non-zero copyup data to save some I/O and network
 	 * bandwidth -- zero copyup data is equivalent to the object not
@@ -2362,9 +2368,6 @@ static int rbd_obj_issue_copyup(struct rbd_obj_request *obj_req, u32 bytes)
 		dout("%s obj_req %p detected zeroes\n", __func__, obj_req);
 		bytes = 0;
 	}
-
-	osd_req_op_cls_init(obj_req->osd_req, 0, CEPH_OSD_OP_CALL, "rbd",
-			    "copyup");
 	osd_req_op_cls_request_data_bvecs(obj_req->osd_req, 0,
 					  obj_req->copyup_bvecs,
 					  obj_req->copyup_bvec_count,

include/linux/ceph/osd_client.h

@@ -440,7 +440,7 @@ extern void osd_req_op_cls_response_data_pages(struct ceph_osd_request *,
 					struct page **pages, u64 length,
 					u32 alignment, bool pages_from_pool,
 					bool own_pages);
-extern void osd_req_op_cls_init(struct ceph_osd_request *osd_req,
+extern int osd_req_op_cls_init(struct ceph_osd_request *osd_req,
 					unsigned int which, u16 opcode,
 					const char *class, const char *method);
 extern int osd_req_op_xattr_init(struct ceph_osd_request *osd_req, unsigned int which,

net/ceph/osd_client.c

@@ -767,7 +767,7 @@ void osd_req_op_extent_dup_last(struct ceph_osd_request *osd_req,
 }
 EXPORT_SYMBOL(osd_req_op_extent_dup_last);
 
-void osd_req_op_cls_init(struct ceph_osd_request *osd_req, unsigned int which,
+int osd_req_op_cls_init(struct ceph_osd_request *osd_req, unsigned int which,
 			u16 opcode, const char *class, const char *method)
 {
 	struct ceph_osd_req_op *op = _osd_req_op_init(osd_req, which,
@@ -779,7 +779,9 @@ void osd_req_op_cls_init(struct ceph_osd_request *osd_req, unsigned int which,
 	BUG_ON(opcode != CEPH_OSD_OP_CALL);
 
 	pagelist = kmalloc(sizeof (*pagelist), GFP_NOFS);
-	BUG_ON(!pagelist);
+	if (!pagelist)
+		return -ENOMEM;
+
 	ceph_pagelist_init(pagelist);
 
 	op->cls.class_name = class;
@@ -799,6 +801,7 @@ void osd_req_op_cls_init(struct ceph_osd_request *osd_req, unsigned int which,
 	osd_req_op_cls_request_info_pagelist(osd_req, which, pagelist);
 
 	op->indata_len = payload_len;
+	return 0;
 }
 EXPORT_SYMBOL(osd_req_op_cls_init);
 
@@ -4928,7 +4931,10 @@ int ceph_osdc_call(struct ceph_osd_client *osdc,
 	if (ret)
 		goto out_put_req;
 
-	osd_req_op_cls_init(req, 0, CEPH_OSD_OP_CALL, class, method);
+	ret = osd_req_op_cls_init(req, 0, CEPH_OSD_OP_CALL, class, method);
+	if (ret)
+		goto out_put_req;
+
 	if (req_page)
 		osd_req_op_cls_request_data_pages(req, 0, &req_page, req_len,
 						  0, false, false);