[patch 14/24] blocK: Restore barrier support for md and probably other virtual devices.

[Greg KH]

2.6.30-stable review patch.  If anyone has any objections, please let us know.

------------------

From: NeilBrown <neilb@xxxxxxx>

commit db64f680ba4b5c56c4be59f0698000df89ff0281 upstream.

The next_ordered flag is only meaningful for devices that use __make_request.
So move the test against next_ordered out of generic code and in to
__make_request

Since this test was added, barriers have not worked on md or any
devices that don't use __make_request and so don't bother to set
next_ordered.  (dm explicitly sets something other than
QUEUE_ORDERED_NONE since
  commit 99360b4c18f7675b50d283301d46d755affe75fd
but notes in the comments that it is otherwise meaningless).

Cc: Ken Milmore <ken.milmore@xxxxxxxxxxxxxx>
Signed-off-by: NeilBrown <neilb@xxxxxxx>
Signed-off-by: Jens Axboe <jens.axboe@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 block/blk-core.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1158,6 +1158,11 @@ static int __make_request(struct request
 
 	nr_sectors = bio_sectors(bio);
 
+	if (bio_barrier(bio) && bio_has_data(bio) &&
+	    (q->next_ordered == QUEUE_ORDERED_NONE)) {
+		bio_endio(bio, -EOPNOTSUPP);
+		return 0;
+	}
 	/*
 	 * low level driver can indicate that it wants pages above a
 	 * certain limit bounced to low memory (ie for highmem, or even
@@ -1461,11 +1466,6 @@ static inline void __generic_make_reques
 			err = -EOPNOTSUPP;
 			goto end_io;
 		}
-		if (bio_barrier(bio) && bio_has_data(bio) &&
-		    (q->next_ordered == QUEUE_ORDERED_NONE)) {
-			err = -EOPNOTSUPP;
-			goto end_io;
-		}
 
 		ret = q->make_request_fn(q, bio);
 	} while (ret);


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