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>

3 files changed, 3 insertions, 10 deletions

diff --git a/include/linux/bio.h b/include/linux/bio.h
index ba679992d39b..35dcdb3589bc 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -66,10 +66,6 @@
 #define bio_offset(bio)         bio_iovec((bio))->bv_offset
 #define bio_segments(bio)       ((bio)->bi_vcnt - (bio)->bi_idx)
 #define bio_sectors(bio)        ((bio)->bi_size >> 9)
-#define bio_empty_barrier(bio) \
-        ((bio->bi_rw & REQ_HARDBARRIER) && \
-         !bio_has_data(bio) && \
-         !(bio->bi_rw & REQ_DISCARD))
 
 static inline unsigned int bio_cur_bytes(struct bio *bio)
 {
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 0437ab6bb54c..46ad5197537a 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -122,7 +122,6 @@ enum rq_flag_bits {
         __REQ_FAILFAST_TRANSPORT, /* no driver retries of transport errors */
         __REQ_FAILFAST_DRIVER,  /* no driver retries of driver errors */
 
-        __REQ_HARDBARRIER,      /* may not be passed by drive either */
         __REQ_SYNC,             /* request is sync (sync write or read) */
         __REQ_META,             /* metadata io request */
         __REQ_DISCARD,          /* request to discard sectors */
@@ -159,7 +158,6 @@ enum rq_flag_bits {
 #define REQ_FAILFAST_DEV        (1 << __REQ_FAILFAST_DEV)
 #define REQ_FAILFAST_TRANSPORT  (1 << __REQ_FAILFAST_TRANSPORT)
 #define REQ_FAILFAST_DRIVER     (1 << __REQ_FAILFAST_DRIVER)
-#define REQ_HARDBARRIER         (1 << __REQ_HARDBARRIER)
 #define REQ_SYNC                (1 << __REQ_SYNC)
 #define REQ_META                (1 << __REQ_META)
 #define REQ_DISCARD             (1 << __REQ_DISCARD)
@@ -168,8 +166,8 @@ enum rq_flag_bits {
 #define REQ_FAILFAST_MASK \
         (REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT | REQ_FAILFAST_DRIVER)
 #define REQ_COMMON_MASK \
-        (REQ_WRITE | REQ_FAILFAST_MASK | REQ_HARDBARRIER | REQ_SYNC | \
-         REQ_META | REQ_DISCARD | REQ_NOIDLE | REQ_FLUSH | REQ_FUA)
+        (REQ_WRITE | REQ_FAILFAST_MASK | REQ_SYNC | REQ_META | REQ_DISCARD | \
+         REQ_NOIDLE | REQ_FLUSH | REQ_FUA)
 #define REQ_CLONE_MASK          REQ_COMMON_MASK
 
 #define REQ_UNPLUG              (1 << __REQ_UNPLUG)
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 5027a599077d..aae86fd10c4f 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -552,8 +552,7 @@ static inline void blk_clear_queue_full(struct request_queue *q, int sync)
  * it already be started by driver.
  */
 #define RQ_NOMERGE_FLAGS        \
-        (REQ_NOMERGE | REQ_STARTED | REQ_HARDBARRIER | REQ_SOFTBARRIER | \
-         REQ_FLUSH | REQ_FUA)
+        (REQ_NOMERGE | REQ_STARTED | REQ_SOFTBARRIER | REQ_FLUSH | REQ_FUA)
 #define rq_mergeable(rq)        \
         (!((rq)->cmd_flags & RQ_NOMERGE_FLAGS) && \
          (((rq)->cmd_flags & REQ_DISCARD) || \