rbd: make rbd_create_rw_ops() return a pointer

Either rbd_create_rw_ops() will succeed, or it will fail because a
memory allocation failed.  Have it just return a valid pointer or
null rather than stuffing a pointer into a provided address and
returning an errno.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com> 

1 files changed, 39 insertions, 31 deletions

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index aba0d71a0345..28670c0c68d5 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -788,22 +788,24 @@ err_out:
 /*
  * helpers for osd request op vectors.
  */
-static int rbd_create_rw_ops(struct ceph_osd_req_op **ops,
-                            int num_ops,
-                            int opcode,
-                            u32 payload_len)
-{
-        *ops = kzalloc(sizeof(struct ceph_osd_req_op) * (num_ops + 1),
-                       GFP_NOIO);
-        if (!*ops)
-                return -ENOMEM;
-        (*ops)[0].op = opcode;
+static struct ceph_osd_req_op *rbd_create_rw_ops(int num_ops,
+                                        int opcode, u32 payload_len)
+{
+        struct ceph_osd_req_op *ops;
+
+        ops = kzalloc(sizeof (*ops) * (num_ops + 1), GFP_NOIO);
+        if (!ops)
+                return NULL;
+
+        ops[0].op = opcode;
+
         /*
          * op extent offset and length will be set later on
          * in calc_raw_layout()
          */
-        (*ops)[0].payload_len = payload_len;
-        return 0;
+        ops[0].payload_len = payload_len;
+
+        return ops;
 }
 
 static void rbd_destroy_ops(struct ceph_osd_req_op *ops)
@@ -1040,8 +1042,9 @@ static int rbd_req_sync_op(struct rbd_device *rbd_dev,
 
         if (!orig_ops) {
                 payload_len = (flags & CEPH_OSD_FLAG_WRITE ? len : 0);
-                ret = rbd_create_rw_ops(&ops, 1, opcode, payload_len);
-                if (ret < 0)
+                ret = -ENOMEM;
+                ops = rbd_create_rw_ops(1, opcode, payload_len);
+                if (!ops)
                         goto done;
 
                 if ((flags & CEPH_OSD_FLAG_WRITE) && buf) {
@@ -1104,8 +1107,9 @@ static int rbd_do_op(struct request *rq,
 
         payload_len = (flags & CEPH_OSD_FLAG_WRITE ? seg_len : 0);
 
-        ret = rbd_create_rw_ops(&ops, 1, opcode, payload_len);
-        if (ret < 0)
+        ret = -ENOMEM;
+        ops = rbd_create_rw_ops(1, opcode, payload_len);
+        if (!ops)
                 goto done;
 
         /* we've taken care of segment sizes earlier when we
@@ -1191,9 +1195,9 @@ static int rbd_req_sync_notify_ack(struct rbd_device *rbd_dev,
         struct ceph_osd_req_op *ops;
         int ret;
 
-        ret = rbd_create_rw_ops(&ops, 1, CEPH_OSD_OP_NOTIFY_ACK, 0);
-        if (ret < 0)
-                return ret;
+        ops = rbd_create_rw_ops(1, CEPH_OSD_OP_NOTIFY_ACK, 0);
+        if (!ops)
+                return -ENOMEM;
 
         ops[0].watch.ver = cpu_to_le64(ver);
         ops[0].watch.cookie = notify_id;
@@ -1241,10 +1245,11 @@ static int rbd_req_sync_watch(struct rbd_device *rbd_dev)
 {
         struct ceph_osd_req_op *ops;
         struct ceph_osd_client *osdc = &rbd_dev->rbd_client->client->osdc;
+        int ret;
 
-        int ret = rbd_create_rw_ops(&ops, 1, CEPH_OSD_OP_WATCH, 0);
-        if (ret < 0)
-                return ret;
+        ops = rbd_create_rw_ops(1, CEPH_OSD_OP_WATCH, 0);
+        if (!ops)
+                return -ENOMEM;
 
         ret = ceph_osdc_create_event(osdc, rbd_watch_cb, 0,
                                      (void *)rbd_dev, &rbd_dev->watch_event);
@@ -1284,10 +1289,11 @@ fail:
 static int rbd_req_sync_unwatch(struct rbd_device *rbd_dev)
 {
         struct ceph_osd_req_op *ops;
+        int ret;
 
-        int ret = rbd_create_rw_ops(&ops, 1, CEPH_OSD_OP_WATCH, 0);
-        if (ret < 0)
-                return ret;
+        ops = rbd_create_rw_ops(1, CEPH_OSD_OP_WATCH, 0);
+        if (!ops)
+                return -ENOMEM;
 
         ops[0].watch.ver = 0;
         ops[0].watch.cookie = cpu_to_le64(rbd_dev->watch_event->cookie);
@@ -1335,9 +1341,9 @@ static int rbd_req_sync_notify(struct rbd_device *rbd_dev)
         int payload_len = sizeof(u32) + sizeof(u32);
         int ret;
 
-        ret = rbd_create_rw_ops(&ops, 1, CEPH_OSD_OP_NOTIFY, payload_len);
-        if (ret < 0)
-                return ret;
+        ops = rbd_create_rw_ops(1, CEPH_OSD_OP_NOTIFY, payload_len);
+        if (!ops)
+                return -ENOMEM;
 
         info.rbd_dev = rbd_dev;
 
@@ -1388,10 +1394,12 @@ static int rbd_req_sync_exec(struct rbd_device *rbd_dev,
         struct ceph_osd_req_op *ops;
         int class_name_len = strlen(class_name);
         int method_name_len = strlen(method_name);
-        int ret = rbd_create_rw_ops(&ops, 1, CEPH_OSD_OP_CALL,
+        int ret;
+
+        ops = rbd_create_rw_ops(1, CEPH_OSD_OP_CALL,
                                     class_name_len + method_name_len + len);
-        if (ret < 0)
-                return ret;
+        if (!ops)
+                return -ENOMEM;
 
         ops[0].cls.class_name = class_name;
         ops[0].cls.class_len = (__u8) class_name_len;