block: max hardware sectors limit wrapper

Implement blk_limits_max_hw_sectors() and make
blk_queue_max_hw_sectors() a wrapper around it.

DM needs this to avoid setting queue_limits' max_hw_sectors and
max_sectors directly.  dm_set_device_limits() now leverages
blk_limits_max_hw_sectors() logic to establish the appropriate
max_hw_sectors minimum (PAGE_SIZE).  Fixes issue where DM was
incorrectly setting max_sectors rather than max_hw_sectors (which
caused dm_merge_bvec()'s max_hw_sectors check to be ineffective).

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@kernel.org
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

1 files changed, 2 insertions, 3 deletions

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index e2da1912a2cb..4d705cea0f8c 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -517,9 +517,8 @@ int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev,
          */
 
         if (q->merge_bvec_fn && !ti->type->merge)
-                limits->max_sectors =
-                        min_not_zero(limits->max_sectors,
-                                     (unsigned int) (PAGE_SIZE >> 9));
+                blk_limits_max_hw_sectors(limits,
+                                          (unsigned int) (PAGE_SIZE >> 9));
         return 0;
 }
 EXPORT_SYMBOL_GPL(dm_set_device_limits);