[SCSI] iscsi: use pageslab

From: FUJITA Tomonori <tomof@acm.org> and zhenyu.z.wang@intel.com:

We cannot handle filesystems like XFS becuase of the pages they
are sending us. We had thought page_count could be used to
work around this, but the correct test is for PageSlab.

The proper solution is to figure out what type of pages
filesystems can use so we do not have to add tests like
this or handle it in the block layer for all network block drivers
but the issue still has not been resolved on fs-devel
so we are sending this patch as a temporary fix.

This is last patch just in case it is Nakd with the explanation
that we need to push the correct fix through fs-devel, mm
or the block layer. The rest of the patchset can live without
the patch, but the driver will not work with filesystems like
XFS.

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>

diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
index 4e4b1061a5e92d589cd207a5cf67429ecef4da89..1b495afe6d1735fb67f9f87769ecc96212acd46a 100644 (file)
--- a/drivers/scsi/iscsi_tcp.c
+++ b/drivers/scsi/iscsi_tcp.c
@@ -109,7 +109,7 @@ iscsi_buf_init_sg(struct iscsi_buf *ibuf, struct scatterlist *sg)
        /*
         * Fastpath: sg element fits into single page
         */
-       if (sg->length + sg->offset <= PAGE_SIZE && page_count(sg->page) >= 2)
+       if (sg->length + sg->offset <= PAGE_SIZE && !PageSlab(sg->page))
                ibuf->use_sendmsg = 0;
        else
                ibuf->use_sendmsg = 1;