RDS: Use page_remainder_alloc() for recv bufs

Instead of splitting up a page into RDS_FRAG_SIZE chunks
ourselves, ask rds_page_remainder_alloc() to do it. While it
is possible PAGE_SIZE > FRAG_SIZE, on x86en it isn't, so having
duplicate "carve up a page into buffers" code seems excessive.

The other modification this spawns is the use of a single
struct scatterlist in rds_page_frag instead of a bare page ptr.
This causes verbosity to increase in some places, and decrease
in others.

Finally, I decided to unify the lifetimes and alloc/free of
rds_page_frag and its page. This is a nice simplification in itself,
but will be extra-nice once we come to adding cmason's recycling
patch.

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

1 files changed, 1 insertions, 6 deletions

diff --git a/net/rds/ib.h b/net/rds/ib.h
index 282ec69fe282..9bb7a7412a44 100644
--- a/net/rds/ib.h
+++ b/net/rds/ib.h
@@ -28,13 +28,9 @@ extern struct list_head rds_ib_devices;
  * try and minimize the amount of memory tied up both the device and
  * socket receive queues.
  */
-/* page offset of the final full frag that fits in the page */
-#define RDS_PAGE_LAST_OFF (((PAGE_SIZE  / RDS_FRAG_SIZE) - 1) * RDS_FRAG_SIZE)
 struct rds_page_frag {
         struct list_head        f_item;
-        struct page             *f_page;
-        unsigned long           f_offset;
-        dma_addr_t              f_mapped;
+        struct scatterlist      f_sg;
 };
 
 struct rds_ib_incoming {
@@ -107,7 +103,6 @@ struct rds_ib_connection {
         struct rds_header       *i_recv_hdrs;
         u64                     i_recv_hdrs_dma;
         struct rds_ib_recv_work *i_recvs;
-        struct rds_page_frag    i_frag;
         u64                     i_ack_recv;     /* last ACK received */
 
         /* sending acks */