RDS: Explicitly allocate rm in sendmsg()

r_m_copy_from_user used to allocate the rm as well as kernel
buffers for the data, and then copy the data in. Now, sendmsg()
allocates the rm, although the data buffer alloc still happens
in r_m_copy_from_user.

SGs are still allocated with rm, but now r_m_alloc_sgs() is
used to reserve them. This allows multiple SG lists to be
allocated from the one rm -- this is important once we also
want to alloc our rdma sgl from this pool.

Signed-off-by: Andy Grover <andy.grover@oracle.com>

1 files changed, 5 insertions, 2 deletions

diff --git a/net/rds/rds.h b/net/rds/rds.h
index 07a750b3fb31..d29c71aabbd4 100644
--- a/net/rds/rds.h
+++ b/net/rds/rds.h
@@ -268,9 +268,11 @@ struct rds_message {
                 struct {
                         unsigned int            m_nents;
                         unsigned int            m_count;
-                        struct scatterlist      m_sg[0];
+                        struct scatterlist      *m_sg;
                 } data;
         };
+        unsigned int            m_used_sgs;
+        unsigned int            m_total_sgs;
 };
 
 /*
@@ -573,7 +575,8 @@ rds_conn_connecting(struct rds_connection *conn)
 
 /* message.c */
 struct rds_message *rds_message_alloc(unsigned int nents, gfp_t gfp);
-struct rds_message *rds_message_copy_from_user(struct iovec *first_iov,
+struct scatterlist *rds_message_alloc_sgs(struct rds_message *rm, int nents);
+int rds_message_copy_from_user(struct rds_message *rm, struct iovec *first_iov,
                                                size_t total_len);
 struct rds_message *rds_message_map_pages(unsigned long *page_addrs, unsigned int total_len);
 void rds_message_populate_header(struct rds_header *hdr, __be16 sport,