+/*
+ * rds_message is getting to be quite complicated, and we'd like to allocate
+ * it all in one go. This figures out how big it needs to be up front.
+ */
+static int rds_rm_size(struct msghdr *msg, int data_len)
+{
+ struct cmsghdr *cmsg;
+ int size = 0;
+ int cmsg_groups = 0;
+ int retval;
+
+ for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg)) {
+ if (!CMSG_OK(msg, cmsg))
+ return -EINVAL;
+
+ if (cmsg->cmsg_level != SOL_RDS)
+ continue;
+
+ switch (cmsg->cmsg_type) {
+ case RDS_CMSG_RDMA_ARGS:
+ cmsg_groups |= 1;
+ retval = rds_rdma_extra_size(CMSG_DATA(cmsg));
+ if (retval < 0)
+ return retval;
+ size += retval;
+
+ break;
+
+ case RDS_CMSG_RDMA_DEST:
+ case RDS_CMSG_RDMA_MAP:
+ cmsg_groups |= 2;
+ /* these are valid but do no add any size */
+ break;
+
+ case RDS_CMSG_ATOMIC_CSWP:
+ case RDS_CMSG_ATOMIC_FADD:
+ case RDS_CMSG_MASKED_ATOMIC_CSWP:
+ case RDS_CMSG_MASKED_ATOMIC_FADD:
+ cmsg_groups |= 1;
+ size += sizeof(struct scatterlist);
+ break;
+
+ default:
+ return -EINVAL;
+ }
+
+ }
+
+ size += ceil(data_len, PAGE_SIZE) * sizeof(struct scatterlist);
+
+ /* Ensure (DEST, MAP) are never used with (ARGS, ATOMIC) */
+ if (cmsg_groups == 3)
+ return -EINVAL;
+
+ return size;
+}
+