dm: bounce_pfn limit added

Device mapper uses its own bounce_pfn that may differ from one on underlying
device. In that way dm can build incorrect requests that contain sg elements
greater than underlying device is able to handle.

This is the cause of slab corruption in i2o layer, occurred on i386 arch when
very long direct IO requests are addressed to dm-over-i2o device.

Signed-off-by: Vasily Averin <vvs@sw.ru>
Cc: <stable@kernel.org>
Cc: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 37c66d1254b5..b8b7c51389fe 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -116,6 +116,7 @@ struct io_restrictions {
         unsigned short          hardsect_size;
         unsigned int            max_segment_size;
         unsigned long           seg_boundary_mask;
+        unsigned long           bounce_pfn;
         unsigned char           no_cluster; /* inverted so that 0 is default */
 };