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>

11 files changed, 11 insertions, 51 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index 17fcb83670c0..4ce953f1b390 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 282e8308f7e2..2569512830d3 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)) {
diff --git a/drivers/block/aoe/aoeblk.c b/drivers/block/aoe/aoeblk.c
index 541e18879965..528f6318ded1 100644
--- a/drivers/block/aoe/aoeblk.c
+++ b/drivers/block/aoe/aoeblk.c
@@ -180,9 +180,6 @@ aoeblk_make_request(struct request_queue *q, struct bio *bio)
                 BUG();
                 bio_endio(bio, -ENXIO);
                 return 0;
-        } else if (bio->bi_rw & REQ_HARDBARRIER) {
-                bio_endio(bio, -EOPNOTSUPP);
-                return 0;
         } else if (bio->bi_io_vec == NULL) {
                 printk(KERN_ERR "aoe: bi_io_vec is NULL\n");
                 BUG();
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 1e5284ef65fa..7ea0bea2f7e3 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -481,12 +481,6 @@ static int do_bio_filebacked(struct loop_device *lo, struct bio *bio)
         if (bio_rw(bio) == WRITE) {
                 struct file *file = lo->lo_backing_file;
 
-                /* REQ_HARDBARRIER is deprecated */
-                if (bio->bi_rw & REQ_HARDBARRIER) {
-                        ret = -EOPNOTSUPP;
-                        goto out;
-                }
-
                 if (bio->bi_rw & REQ_FLUSH) {
                         ret = vfs_fsync(file, 0);
                         if (unlikely(ret && ret != -EINVAL)) {
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 06e2812ba124..255035cfc88a 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -289,8 +289,6 @@ static int blkif_queue_request(struct request *req)
 
         ring_req->operation = rq_data_dir(req) ?
                 BLKIF_OP_WRITE : BLKIF_OP_READ;
-        if (req->cmd_flags & REQ_HARDBARRIER)
-                ring_req->operation = BLKIF_OP_WRITE_BARRIER;
 
         ring_req->nr_segments = blk_rq_map_sg(req->q, req, info->sg);
         BUG_ON(ring_req->nr_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST);
diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 1de30eb83bb0..f3cf924a2cd9 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -320,19 +320,11 @@ static int scsi_check_sense(struct scsi_cmnd *scmd)
                                     "changed. The Linux SCSI layer does not "
                                     "automatically adjust these parameters.\n");
 
-                if (scmd->request->cmd_flags & REQ_HARDBARRIER)
-                        /*
-                         * barrier requests should always retry on UA
-                         * otherwise block will get a spurious error
-                         */
-                        return NEEDS_RETRY;
-                else
-                        /*
-                         * for normal (non barrier) commands, pass the
-                         * UA upwards for a determination in the
-                         * completion functions
-                         */
-                        return SUCCESS;
+                /*
+                 * Pass the UA upwards for a determination in the completion
+                 * functions.
+                 */
+                return SUCCESS;
 
                 /* these three are not supported */
         case COPY_ABORTED:
diff --git a/drivers/usb/storage/uas.c b/drivers/usb/storage/uas.c
index 2054b1e25a65..d1268191acbd 100644
--- a/drivers/usb/storage/uas.c
+++ b/drivers/usb/storage/uas.c
@@ -331,10 +331,7 @@ static struct urb *uas_alloc_cmd_urb(struct uas_dev_info *devinfo, gfp_t gfp,
 
         iu->iu_id = IU_ID_COMMAND;
         iu->tag = cpu_to_be16(stream_id);
-        if (sdev->ordered_tags && (cmnd->request->cmd_flags & REQ_HARDBARRIER))
-                iu->prio_attr = UAS_ORDERED_TAG;
-        else
-                iu->prio_attr = UAS_SIMPLE_TAG;
+        iu->prio_attr = UAS_SIMPLE_TAG;
         iu->len = len;
         int_to_scsilun(sdev->lun, &iu->lun);
         memcpy(iu->cdb, cmnd->cmnd, cmnd->cmd_len);
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 {