[SCSI] iscsi: data digest page cache usage fix

Users can write to a page while we are sending it and making
digest calculations. This ends up causing us to retry the command
when a digest error is later reported. By using sock_no_sendpage
when data digests are calculated we can avoid a lot of (not all but it
helps) the retries becuase sock_no_sendpage is not zero copy.

Signed-off-by: Alex Aizman <itn780@yahoo.com>
Signed-off-by: Dmitry Yusupov <dmitry_yus@yahoo.com>
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/scsi/iscsi_tcp.h b/drivers/scsi/iscsi_tcp.h
index 9badafe8820d..c8bb5b0bcb4b 100644
--- a/drivers/scsi/iscsi_tcp.h
+++ b/drivers/scsi/iscsi_tcp.h
@@ -191,6 +191,8 @@ struct iscsi_conn {
         uint32_t                sendpage_failures_cnt;
         uint32_t                discontiguous_hdr_cnt;
         uint32_t                eh_abort_cnt;
+
+        ssize_t (*sendpage)(struct socket *, struct page *, int, size_t, int);
 };
 
 struct iscsi_session {