block: remove REQ_HARDBARRIER

REQ_HARDBARRIER is dead now, so remove the leftovers.  What's left
at this point is:

 - various checks inside the block layer.
 - sanity checks in bio based drivers.
 - now unused bio_empty_barrier helper.
 - Xen blockfront use of BLKIF_OP_WRITE_BARRIER - it's dead for a while,
   but Xen really needs to sort out it's barrier situaton.
 - setting of ordered tags in uas - dead code copied from old scsi
   drivers.
 - scsi different retry for barriers - it's dead and should have been
   removed when flushes were converted to FS requests.
 - blktrace handling of barriers - removed.  Someone who knows blktrace
   better should add support for REQ_FLUSH and REQ_FUA, though.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

2 files changed, 2 insertions, 9 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index 17fcb83670c..4ce953f1b39 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1194,13 +1194,6 @@ static int __make_request(struct request_queue *q, struct bio *bio)
         int where = ELEVATOR_INSERT_SORT;
         int rw_flags;
 
-        /* REQ_HARDBARRIER is no more */
-        if (WARN_ONCE(bio->bi_rw & REQ_HARDBARRIER,
-                "block: HARDBARRIER is deprecated, use FLUSH/FUA instead\n")) {
-                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
diff --git a/block/elevator.c b/block/elevator.c
index 282e8308f7e..2569512830d 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -429,7 +429,7 @@ void elv_dispatch_sort(struct request_queue *q, struct request *rq)
         q->nr_sorted--;
 
         boundary = q->end_sector;
-        stop_flags = REQ_SOFTBARRIER | REQ_HARDBARRIER | REQ_STARTED;
+        stop_flags = REQ_SOFTBARRIER | REQ_STARTED;
         list_for_each_prev(entry, &q->queue_head) {
                 struct request *pos = list_entry_rq(entry);
 
@@ -691,7 +691,7 @@ void elv_insert(struct request_queue *q, struct request *rq, int where)
 void __elv_add_request(struct request_queue *q, struct request *rq, int where,
                        int plug)
 {
-        if (rq->cmd_flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) {
+        if (rq->cmd_flags & REQ_SOFTBARRIER) {
                 /* barriers are scheduling boundary, update end_sector */
                 if (rq->cmd_type == REQ_TYPE_FS ||
                     (rq->cmd_flags & REQ_DISCARD)) {