[PATCH] rds: rds-stress show all zeros after few minutes

[shamir rabinovitch <shamir.rabinovitch@oracle.com>]

Issue can be seen on platforms that use 8K and above page size
while rds fragment size is 4K. On those platforms single page is
shared between 2 or more rds fragments. Each fragment has it's own
offeset and rds cong map code need to take this offset to account.
Not taking this offset to account lead to reading the data fragment
as congestion map fragment and hang of the rds transmit due to far
cong map corruption.

Reviewed-by: Wengang Wang <wen.gang.wang@oracle.com>
Reviewed-by: Ajaykumar Hotchandani <ajaykumar.hotchandani@oracle.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Tested-by: Anand Bibhuti <anand.bibhuti@oracle.com>

Signed-off-by: shamir rabinovitch <shamir.rabinovitch@oracle.com>
---
 net/rds/ib_recv.c |    2 +-
 net/rds/iw_recv.c |    2 +-
 net/rds/page.c    |    5 +++--
 3 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/net/rds/ib_recv.c b/net/rds/ib_recv.c
index 977fb86..abc8cc8 100644
--- a/net/rds/ib_recv.c
+++ b/net/rds/ib_recv.c
@@ -796,7 +796,7 @@ static void rds_ib_cong_recv(struct rds_connection *conn,
 
 		addr = kmap_atomic(sg_page(&frag->f_sg));
 
-		src = addr + frag_off;
+		src = addr + frag->f_sg.offset + frag_off;
 		dst = (void *)map->m_page_addrs[map_page] + map_off;
 		for (k = 0; k < to_copy; k += 8) {
 			/* Record ports that became uncongested, ie
diff --git a/net/rds/iw_recv.c b/net/rds/iw_recv.c
index a66d179..62a1738 100644
--- a/net/rds/iw_recv.c
+++ b/net/rds/iw_recv.c
@@ -585,7 +585,7 @@ static void rds_iw_cong_recv(struct rds_connection *conn,
 
 		addr = kmap_atomic(frag->f_page);
 
-		src = addr + frag_off;
+		src = addr +  frag->f_offset + frag_off;
 		dst = (void *)map->m_page_addrs[map_page] + map_off;
 		for (k = 0; k < to_copy; k += 8) {
 			/* Record ports that became uncongested, ie
diff --git a/net/rds/page.c b/net/rds/page.c
index 5a14e6d..715cbaa 100644
--- a/net/rds/page.c
+++ b/net/rds/page.c
@@ -135,8 +135,9 @@ int rds_page_remainder_alloc(struct scatterlist *scat, unsigned long bytes,
 			if (rem->r_offset != 0)
 				rds_stats_inc(s_page_remainder_hit);
 
-			rem->r_offset += bytes;
-			if (rem->r_offset == PAGE_SIZE) {
+			/* some hw (e.g. sparc) require aligned memory */
+			rem->r_offset += ALIGN(bytes, 8);
+			if (rem->r_offset >= PAGE_SIZE) {
 				__free_page(rem->r_page);
 				rem->r_page = NULL;
 			}
-- 
1.7.1