Merge branch 'for-2.6.37/barrier' of git://git.kernel.dk/linux-2.6-block

* 'for-2.6.37/barrier' of git://git.kernel.dk/linux-2.6-block: (46 commits)
  xen-blkfront: disable barrier/flush write support
  Added blk-lib.c and blk-barrier.c was renamed to blk-flush.c
  block: remove BLKDEV_IFL_WAIT
  aic7xxx_old: removed unused 'req' variable
  block: remove the BH_Eopnotsupp flag
  block: remove the BLKDEV_IFL_BARRIER flag
  block: remove the WRITE_BARRIER flag
  swap: do not send discards as barriers
  fat: do not send discards as barriers
  ext4: do not send discards as barriers
  jbd2: replace barriers with explicit flush / FUA usage
  jbd2: Modify ASYNC_COMMIT code to not rely on queue draining on barrier
  jbd: replace barriers with explicit flush / FUA usage
  nilfs2: replace barriers with explicit flush / FUA usage
  reiserfs: replace barriers with explicit flush / FUA usage
  gfs2: replace barriers with explicit flush / FUA usage
  btrfs: replace barriers with explicit flush / FUA usage
  xfs: replace barriers with explicit flush / FUA usage
  block: pass gfp_mask and flags to sb_issue_discard
  dm: convey that all flushes are processed as empty
  ...

Documentation/DocBook/kernel-api.tmpl

@@ -257,7 +257,8 @@ X!Earch/x86/kernel/mca_32.c
 !Iblock/blk-sysfs.c
 !Eblock/blk-settings.c
 !Eblock/blk-exec.c
-!Eblock/blk-barrier.c
+!Eblock/blk-flush.c
+!Eblock/blk-lib.c
 !Eblock/blk-tag.c
 !Iblock/blk-tag.c
 !Eblock/blk-integrity.c

Documentation/block/00-INDEX

@@ -1,7 +1,5 @@
 00-INDEX
 	- This file
-barrier.txt
-	- I/O Barriers
 biodoc.txt
 	- Notes on the Generic Block Layer Rewrite in Linux 2.5
 capability.txt
@@ -16,3 +14,5 @@ stat.txt
 	- Block layer statistics in /sys/block/<dev>/stat
 switching-sched.txt
 	- Switching I/O schedulers at runtime
+writeback_cache_control.txt
+	- Control of volatile write back caches

Documentation/block/barrier.txt

@@ -1,261 +0,0 @@
-I/O Barriers
-============
-Tejun Heo <htejun@gmail.com>, July 22 2005
-
-I/O barrier requests are used to guarantee ordering around the barrier
-requests.  Unless you're crazy enough to use disk drives for
-implementing synchronization constructs (wow, sounds interesting...),
-the ordering is meaningful only for write requests for things like
-journal checkpoints.  All requests queued before a barrier request
-must be finished (made it to the physical medium) before the barrier
-request is started, and all requests queued after the barrier request
-must be started only after the barrier request is finished (again,
-made it to the physical medium).
-
-In other words, I/O barrier requests have the following two properties.
-
-1. Request ordering
-
-Requests cannot pass the barrier request.  Preceding requests are
-processed before the barrier and following requests after.
-
-Depending on what features a drive supports, this can be done in one
-of the following three ways.
-
-i. For devices which have queue depth greater than 1 (TCQ devices) and
-support ordered tags, block layer can just issue the barrier as an
-ordered request and the lower level driver, controller and drive
-itself are responsible for making sure that the ordering constraint is
-met.  Most modern SCSI controllers/drives should support this.
-
-NOTE: SCSI ordered tag isn't currently used due to limitation in the
-      SCSI midlayer, see the following random notes section.
-
-ii. For devices which have queue depth greater than 1 but don't
-support ordered tags, block layer ensures that the requests preceding
-a barrier request finishes before issuing the barrier request.  Also,
-it defers requests following the barrier until the barrier request is
-finished.  Older SCSI controllers/drives and SATA drives fall in this
-category.
-
-iii. Devices which have queue depth of 1.  This is a degenerate case
-of ii.  Just keeping issue order suffices.  Ancient SCSI
-controllers/drives and IDE drives are in this category.
-
-2. Forced flushing to physical medium
-
-Again, if you're not gonna do synchronization with disk drives (dang,
-it sounds even more appealing now!), the reason you use I/O barriers
-is mainly to protect filesystem integrity when power failure or some
-other events abruptly stop the drive from operating and possibly make
-the drive lose data in its cache.  So, I/O barriers need to guarantee
-that requests actually get written to non-volatile medium in order.
-
-There are four cases,
-
-i. No write-back cache.  Keeping requests ordered is enough.
-
-ii. Write-back cache but no flush operation.  There's no way to
-guarantee physical-medium commit order.  This kind of devices can't to
-I/O barriers.
-
-iii. Write-back cache and flush operation but no FUA (forced unit
-access).  We need two cache flushes - before and after the barrier
-request.
-
-iv. Write-back cache, flush operation and FUA.  We still need one
-flush to make sure requests preceding a barrier are written to medium,
-but post-barrier flush can be avoided by using FUA write on the
-barrier itself.
-
-
-How to support barrier requests in drivers
-------------------------------------------
-
-All barrier handling is done inside block layer proper.  All low level
-drivers have to are implementing its prepare_flush_fn and using one
-the following two functions to indicate what barrier type it supports
-and how to prepare flush requests.  Note that the term 'ordered' is
-used to indicate the whole sequence of performing barrier requests
-including draining and flushing.
-
-typedef void (prepare_flush_fn)(struct request_queue *q, struct request *rq);
-
-int blk_queue_ordered(struct request_queue *q, unsigned ordered,
-		      prepare_flush_fn *prepare_flush_fn);
-
-@q			: the queue in question
-@ordered		: the ordered mode the driver/device supports
-@prepare_flush_fn	: this function should prepare @rq such that it
-			  flushes cache to physical medium when executed
-
-For example, SCSI disk driver's prepare_flush_fn looks like the
-following.
-
-static void sd_prepare_flush(struct request_queue *q, struct request *rq)
-{
-	memset(rq->cmd, 0, sizeof(rq->cmd));
-	rq->cmd_type = REQ_TYPE_BLOCK_PC;
-	rq->timeout = SD_TIMEOUT;
-	rq->cmd[0] = SYNCHRONIZE_CACHE;
-	rq->cmd_len = 10;
-}
-
-The following seven ordered modes are supported.  The following table
-shows which mode should be used depending on what features a
-device/driver supports.  In the leftmost column of table,
-QUEUE_ORDERED_ prefix is omitted from the mode names to save space.
-
-The table is followed by description of each mode.  Note that in the
-descriptions of QUEUE_ORDERED_DRAIN*, '=>' is used whereas '->' is
-used for QUEUE_ORDERED_TAG* descriptions.  '=>' indicates that the
-preceding step must be complete before proceeding to the next step.
-'->' indicates that the next step can start as soon as the previous
-step is issued.
-
-	    write-back cache	ordered tag	flush		FUA
------------------------------------------------------------------------
-NONE		yes/no		N/A		no		N/A
-DRAIN		no		no		N/A		N/A
-DRAIN_FLUSH	yes		no		yes		no
-DRAIN_FUA	yes		no		yes		yes
-TAG		no		yes		N/A		N/A
-TAG_FLUSH	yes		yes		yes		no
-TAG_FUA		yes		yes		yes		yes
-
-
-QUEUE_ORDERED_NONE
-	I/O barriers are not needed and/or supported.
-
-	Sequence: N/A
-
-QUEUE_ORDERED_DRAIN
-	Requests are ordered by draining the request queue and cache
-	flushing isn't needed.
-
-	Sequence: drain => barrier
-
-QUEUE_ORDERED_DRAIN_FLUSH
-	Requests are ordered by draining the request queue and both
-	pre-barrier and post-barrier cache flushings are needed.
-
-	Sequence: drain => preflush => barrier => postflush
-
-QUEUE_ORDERED_DRAIN_FUA
-	Requests are ordered by draining the request queue and
-	pre-barrier cache flushing is needed.  By using FUA on barrier
-	request, post-barrier flushing can be skipped.
-
-	Sequence: drain => preflush => barrier
-
-QUEUE_ORDERED_TAG
-	Requests are ordered by ordered tag and cache flushing isn't
-	needed.
-
-	Sequence: barrier
-
-QUEUE_ORDERED_TAG_FLUSH
-	Requests are ordered by ordered tag and both pre-barrier and
-	post-barrier cache flushings are needed.
-
-	Sequence: preflush -> barrier -> postflush
-
-QUEUE_ORDERED_TAG_FUA
-	Requests are ordered by ordered tag and pre-barrier cache
-	flushing is needed.  By using FUA on barrier request,
-	post-barrier flushing can be skipped.
-
-	Sequence: preflush -> barrier
-
-
-Random notes/caveats
---------------------
-
-* SCSI layer currently can't use TAG ordering even if the drive,
-controller and driver support it.  The problem is that SCSI midlayer
-request dispatch function is not atomic.  It releases queue lock and
-switch to SCSI host lock during issue and it's possible and likely to
-happen in time that requests change their relative positions.  Once
-this problem is solved, TAG ordering can be enabled.
-
-* Currently, no matter which ordered mode is used, there can be only
-one barrier request in progress.  All I/O barriers are held off by
-block layer until the previous I/O barrier is complete.  This doesn't
-make any difference for DRAIN ordered devices, but, for TAG ordered
-devices with very high command latency, passing multiple I/O barriers
-to low level *might* be helpful if they are very frequent.  Well, this
-certainly is a non-issue.  I'm writing this just to make clear that no
-two I/O barrier is ever passed to low-level driver.
-
-* Completion order.  Requests in ordered sequence are issued in order
-but not required to finish in order.  Barrier implementation can
-handle out-of-order completion of ordered sequence.  IOW, the requests
-MUST be processed in order but the hardware/software completion paths
-are allowed to reorder completion notifications - eg. current SCSI
-midlayer doesn't preserve completion order during error handling.
-
-* Requeueing order.  Low-level drivers are free to requeue any request
-after they removed it from the request queue with
-blkdev_dequeue_request().  As barrier sequence should be kept in order
-when requeued, generic elevator code takes care of putting requests in
-order around barrier.  See blk_ordered_req_seq() and
-ELEVATOR_INSERT_REQUEUE handling in __elv_add_request() for details.
-
-Note that block drivers must not requeue preceding requests while
-completing latter requests in an ordered sequence.  Currently, no
-error checking is done against this.
-
-* Error handling.  Currently, block layer will report error to upper
-layer if any of requests in an ordered sequence fails.  Unfortunately,
-this doesn't seem to be enough.  Look at the following request flow.
-QUEUE_ORDERED_TAG_FLUSH is in use.
-
- [0] [1] [2] [3] [pre] [barrier] [post] < [4] [5] [6] ... >
-					  still in elevator
-
-Let's say request [2], [3] are write requests to update file system
-metadata (journal or whatever) and [barrier] is used to mark that
-those updates are valid.  Consider the following sequence.
-
- i.	Requests [0] ~ [post] leaves the request queue and enters
-	low-level driver.
- ii.	After a while, unfortunately, something goes wrong and the
-	drive fails [2].  Note that any of [0], [1] and [3] could have
-	completed by this time, but [pre] couldn't have been finished
-	as the drive must process it in order and it failed before
-	processing that command.
- iii.	Error handling kicks in and determines that the error is
-	unrecoverable and fails [2], and resumes operation.
- iv.	[pre] [barrier] [post] gets processed.
- v.	*BOOM* power fails
-
-The problem here is that the barrier request is *supposed* to indicate
-that filesystem update requests [2] and [3] made it safely to the
-physical medium and, if the machine crashes after the barrier is
-written, filesystem recovery code can depend on that.  Sadly, that
-isn't true in this case anymore.  IOW, the success of a I/O barrier
-should also be dependent on success of some of the preceding requests,
-where only upper layer (filesystem) knows what 'some' is.
-
-This can be solved by implementing a way to tell the block layer which
-requests affect the success of the following barrier request and
-making lower lever drivers to resume operation on error only after
-block layer tells it to do so.
-
-As the probability of this happening is very low and the drive should
-be faulty, implementing the fix is probably an overkill.  But, still,
-it's there.
-
-* In previous drafts of barrier implementation, there was fallback
-mechanism such that, if FUA or ordered TAG fails, less fancy ordered
-mode can be selected and the failed barrier request is retried
-automatically.  The rationale for this feature was that as FUA is
-pretty new in ATA world and ordered tag was never used widely, there
-could be devices which report to support those features but choke when
-actually given such requests.
-
- This was removed for two reasons 1. it's an overkill 2. it's
-impossible to implement properly when TAG ordering is used as low
-level drivers resume after an error automatically.  If it's ever
-needed adding it back and modifying low level drivers accordingly
-shouldn't be difficult.

Documentation/block/writeback_cache_control.txt

@@ -0,0 +1,86 @@
+
+Explicit volatile write back cache control
+=====================================
+
+Introduction
+------------
+
+Many storage devices, especially in the consumer market, come with volatile
+write back caches.  That means the devices signal I/O completion to the
+operating system before data actually has hit the non-volatile storage.  This
+behavior obviously speeds up various workloads, but it means the operating
+system needs to force data out to the non-volatile storage when it performs
+a data integrity operation like fsync, sync or an unmount.
+
+The Linux block layer provides two simple mechanisms that let filesystems
+control the caching behavior of the storage device.  These mechanisms are
+a forced cache flush, and the Force Unit Access (FUA) flag for requests.
+
+
+Explicit cache flushes
+----------------------
+
+The REQ_FLUSH flag can be OR ed into the r/w flags of a bio submitted from
+the filesystem and will make sure the volatile cache of the storage device
+has been flushed before the actual I/O operation is started.  This explicitly
+guarantees that previously completed write requests are on non-volatile
+storage before the flagged bio starts. In addition the REQ_FLUSH flag can be
+set on an otherwise empty bio structure, which causes only an explicit cache
+flush without any dependent I/O.  It is recommend to use
+the blkdev_issue_flush() helper for a pure cache flush.
+
+
+Forced Unit Access
+-----------------
+
+The REQ_FUA flag can be OR ed into the r/w flags of a bio submitted from the
+filesystem and will make sure that I/O completion for this request is only
+signaled after the data has been committed to non-volatile storage.
+
+
+Implementation details for filesystems
+--------------------------------------
+
+Filesystems can simply set the REQ_FLUSH and REQ_FUA bits and do not have to
+worry if the underlying devices need any explicit cache flushing and how
+the Forced Unit Access is implemented.  The REQ_FLUSH and REQ_FUA flags
+may both be set on a single bio.
+
+
+Implementation details for make_request_fn based block drivers
+--------------------------------------------------------------
+
+These drivers will always see the REQ_FLUSH and REQ_FUA bits as they sit
+directly below the submit_bio interface.  For remapping drivers the REQ_FUA
+bits need to be propagated to underlying devices, and a global flush needs
+to be implemented for bios with the REQ_FLUSH bit set.  For real device
+drivers that do not have a volatile cache the REQ_FLUSH and REQ_FUA bits
+on non-empty bios can simply be ignored, and REQ_FLUSH requests without
+data can be completed successfully without doing any work.  Drivers for
+devices with volatile caches need to implement the support for these
+flags themselves without any help from the block layer.
+
+
+Implementation details for request_fn based block drivers
+--------------------------------------------------------------
+
+For devices that do not support volatile write caches there is no driver
+support required, the block layer completes empty REQ_FLUSH requests before
+entering the driver and strips off the REQ_FLUSH and REQ_FUA bits from
+requests that have a payload.  For devices with volatile write caches the
+driver needs to tell the block layer that it supports flushing caches by
+doing:
+
+	blk_queue_flush(sdkp->disk->queue, REQ_FLUSH);
+
+and handle empty REQ_FLUSH requests in its prep_fn/request_fn.  Note that
+REQ_FLUSH requests with a payload are automatically turned into a sequence
+of an empty REQ_FLUSH request followed by the actual write by the block
+layer.  For devices that also support the FUA bit the block layer needs
+to be told to pass through the REQ_FUA bit using:
+
+	blk_queue_flush(sdkp->disk->queue, REQ_FLUSH | REQ_FUA);
+
+and the driver must handle write requests that have the REQ_FUA bit set
+in prep_fn/request_fn.  If the FUA bit is not natively supported the block
+layer turns it into an empty REQ_FLUSH request after the actual write.

Documentation/lguest/lguest.c

@@ -1639,15 +1639,6 @@ static void blk_request(struct virtqueue *vq)
 	 */
 	off = out->sector * 512;
 
-	/*
-	 * The block device implements "barriers", where the Guest indicates
-	 * that it wants all previous writes to occur before this write.  We
-	 * don't have a way of asking our kernel to do a barrier, so we just
-	 * synchronize all the data in the file.  Pretty poor, no?
-	 */
-	if (out->type & VIRTIO_BLK_T_BARRIER)
-		fdatasync(vblk->fd);
-
 	/*
 	 * In general the virtio block driver is allowed to try SCSI commands.
 	 * It'd be nice if we supported eject, for example, but we don't.
@@ -1680,6 +1671,13 @@ static void blk_request(struct virtqueue *vq)
 			/* Die, bad Guest, die. */
 			errx(1, "Write past end %llu+%u", off, ret);
 		}
+
+		wlen = sizeof(*in);
+		*in = (ret >= 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR);
+	} else if (out->type & VIRTIO_BLK_T_FLUSH) {
+		/* Flush */
+		ret = fdatasync(vblk->fd);
+		verbose("FLUSH fdatasync: %i\n", ret);
 		wlen = sizeof(*in);
 		*in = (ret >= 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR);
 	} else {
@@ -1703,15 +1701,6 @@ static void blk_request(struct virtqueue *vq)
 		}
 	}
 
-	/*
-	 * OK, so we noted that it was pretty poor to use an fdatasync as a
-	 * barrier.  But Christoph Hellwig points out that we need a sync
-	 * *afterwards* as well: "Barriers specify no reordering to the front
-	 * or the back."  And Jens Axboe confirmed it, so here we are:
-	 */
-	if (out->type & VIRTIO_BLK_T_BARRIER)
-		fdatasync(vblk->fd);
-
 	/* Finished that request. */
 	add_used(vq, head, wlen);
 }
@@ -1736,8 +1725,8 @@ static void setup_block_file(const char *filename)
 	vblk->fd = open_or_die(filename, O_RDWR|O_LARGEFILE);
 	vblk->len = lseek64(vblk->fd, 0, SEEK_END);
 
-	/* We support barriers. */
-	add_feature(dev, VIRTIO_BLK_F_BARRIER);
+	/* We support FLUSH. */
+	add_feature(dev, VIRTIO_BLK_F_FLUSH);
 
 	/* Tell Guest how many sectors this device has. */
 	conf.capacity = cpu_to_le64(vblk->len / 512);

block/Makefile

@@ -3,7 +3,7 @@
 #
 
 obj-$(CONFIG_BLOCK) := elevator.o blk-core.o blk-tag.o blk-sysfs.o \
-			blk-barrier.o blk-settings.o blk-ioc.o blk-map.o \
+			blk-flush.o blk-settings.o blk-ioc.o blk-map.o \
 			blk-exec.o blk-merge.o blk-softirq.o blk-timeout.o \
 			blk-iopoll.o blk-lib.o ioctl.o genhd.o scsi_ioctl.o
 

block/blk-barrier.c

@@ -1,350 +0,0 @@
-/*
- * Functions related to barrier IO handling
- */
-#include <linux/kernel.h>
-#include <linux/module.h>
-#include <linux/bio.h>
-#include <linux/blkdev.h>
-#include <linux/gfp.h>
-
-#include "blk.h"
-
-/**
- * blk_queue_ordered - does this queue support ordered writes
- * @q:        the request queue
- * @ordered:  one of QUEUE_ORDERED_*
- *
- * Description:
- *   For journalled file systems, doing ordered writes on a commit
- *   block instead of explicitly doing wait_on_buffer (which is bad
- *   for performance) can be a big win. Block drivers supporting this
- *   feature should call this function and indicate so.
- *
- **/
-int blk_queue_ordered(struct request_queue *q, unsigned ordered)
-{
-	if (ordered != QUEUE_ORDERED_NONE &&
-	    ordered != QUEUE_ORDERED_DRAIN &&
-	    ordered != QUEUE_ORDERED_DRAIN_FLUSH &&
-	    ordered != QUEUE_ORDERED_DRAIN_FUA &&
-	    ordered != QUEUE_ORDERED_TAG &&
-	    ordered != QUEUE_ORDERED_TAG_FLUSH &&
-	    ordered != QUEUE_ORDERED_TAG_FUA) {
-		printk(KERN_ERR "blk_queue_ordered: bad value %d\n", ordered);
-		return -EINVAL;
-	}
-
-	q->ordered = ordered;
-	q->next_ordered = ordered;
-
-	return 0;
-}
-EXPORT_SYMBOL(blk_queue_ordered);
-
-/*
- * Cache flushing for ordered writes handling
- */
-unsigned blk_ordered_cur_seq(struct request_queue *q)
-{
-	if (!q->ordseq)
-		return 0;
-	return 1 << ffz(q->ordseq);
-}
-
-unsigned blk_ordered_req_seq(struct request *rq)
-{
-	struct request_queue *q = rq->q;
-
-	BUG_ON(q->ordseq == 0);
-
-	if (rq == &q->pre_flush_rq)
-		return QUEUE_ORDSEQ_PREFLUSH;
-	if (rq == &q->bar_rq)
-		return QUEUE_ORDSEQ_BAR;
-	if (rq == &q->post_flush_rq)
-		return QUEUE_ORDSEQ_POSTFLUSH;
-
-	/*
-	 * !fs requests don't need to follow barrier ordering.  Always
-	 * put them at the front.  This fixes the following deadlock.
-	 *
-	 * http://thread.gmane.org/gmane.linux.kernel/537473
-	 */
-	if (rq->cmd_type != REQ_TYPE_FS)
-		return QUEUE_ORDSEQ_DRAIN;
-
-	if ((rq->cmd_flags & REQ_ORDERED_COLOR) ==
-	    (q->orig_bar_rq->cmd_flags & REQ_ORDERED_COLOR))
-		return QUEUE_ORDSEQ_DRAIN;
-	else
-		return QUEUE_ORDSEQ_DONE;
-}
-
-bool blk_ordered_complete_seq(struct request_queue *q, unsigned seq, int error)
-{
-	struct request *rq;
-
-	if (error && !q->orderr)
-		q->orderr = error;
-
-	BUG_ON(q->ordseq & seq);
-	q->ordseq |= seq;
-
-	if (blk_ordered_cur_seq(q) != QUEUE_ORDSEQ_DONE)
-		return false;
-
-	/*
-	 * Okay, sequence complete.
-	 */
-	q->ordseq = 0;
-	rq = q->orig_bar_rq;
-	__blk_end_request_all(rq, q->orderr);
-	return true;
-}
-
-static void pre_flush_end_io(struct request *rq, int error)
-{
-	elv_completed_request(rq->q, rq);
-	blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_PREFLUSH, error);
-}
-
-static void bar_end_io(struct request *rq, int error)
-{
-	elv_completed_request(rq->q, rq);
-	blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_BAR, error);
-}
-
-static void post_flush_end_io(struct request *rq, int error)
-{
-	elv_completed_request(rq->q, rq);
-	blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_POSTFLUSH, error);
-}
-
-static void queue_flush(struct request_queue *q, unsigned which)
-{
-	struct request *rq;
-	rq_end_io_fn *end_io;
-
-	if (which == QUEUE_ORDERED_DO_PREFLUSH) {
-		rq = &q->pre_flush_rq;
-		end_io = pre_flush_end_io;
-	} else {
-		rq = &q->post_flush_rq;
-		end_io = post_flush_end_io;
-	}
-
-	blk_rq_init(q, rq);
-	rq->cmd_type = REQ_TYPE_FS;
-	rq->cmd_flags = REQ_HARDBARRIER | REQ_FLUSH;
-	rq->rq_disk = q->orig_bar_rq->rq_disk;
-	rq->end_io = end_io;
-
-	elv_insert(q, rq, ELEVATOR_INSERT_FRONT);
-}
-
-static inline bool start_ordered(struct request_queue *q, struct request **rqp)
-{
-	struct request *rq = *rqp;
-	unsigned skip = 0;
-
-	q->orderr = 0;
-	q->ordered = q->next_ordered;
-	q->ordseq |= QUEUE_ORDSEQ_STARTED;
-
-	/*
-	 * For an empty barrier, there's no actual BAR request, which
-	 * in turn makes POSTFLUSH unnecessary.  Mask them off.
-	 */
-	if (!blk_rq_sectors(rq)) {
-		q->ordered &= ~(QUEUE_ORDERED_DO_BAR |
-				QUEUE_ORDERED_DO_POSTFLUSH);
-		/*
-		 * Empty barrier on a write-through device w/ ordered
-		 * tag has no command to issue and without any command
-		 * to issue, ordering by tag can't be used.  Drain
-		 * instead.
-		 */
-		if ((q->ordered & QUEUE_ORDERED_BY_TAG) &&
-		    !(q->ordered & QUEUE_ORDERED_DO_PREFLUSH)) {
-			q->ordered &= ~QUEUE_ORDERED_BY_TAG;
-			q->ordered |= QUEUE_ORDERED_BY_DRAIN;
-		}
-	}
-
-	/* stash away the original request */
-	blk_dequeue_request(rq);
-	q->orig_bar_rq = rq;
-	rq = NULL;
-
-	/*
-	 * Queue ordered sequence.  As we stack them at the head, we
-	 * need to queue in reverse order.  Note that we rely on that
-	 * no fs request uses ELEVATOR_INSERT_FRONT and thus no fs
-	 * request gets inbetween ordered sequence.
-	 */
-	if (q->ordered & QUEUE_ORDERED_DO_POSTFLUSH) {
-		queue_flush(q, QUEUE_ORDERED_DO_POSTFLUSH);
-		rq = &q->post_flush_rq;
-	} else
-		skip |= QUEUE_ORDSEQ_POSTFLUSH;
-
-	if (q->ordered & QUEUE_ORDERED_DO_BAR) {
-		rq = &q->bar_rq;
-
-		/* initialize proxy request and queue it */
-		blk_rq_init(q, rq);
-		if (bio_data_dir(q->orig_bar_rq->bio) == WRITE)
-			rq->cmd_flags |= REQ_WRITE;
-		if (q->ordered & QUEUE_ORDERED_DO_FUA)
-			rq->cmd_flags |= REQ_FUA;
-		init_request_from_bio(rq, q->orig_bar_rq->bio);
-		rq->end_io = bar_end_io;
-
-		elv_insert(q, rq, ELEVATOR_INSERT_FRONT);
-	} else
-		skip |= QUEUE_ORDSEQ_BAR;
-
-	if (q->ordered & QUEUE_ORDERED_DO_PREFLUSH) {
-		queue_flush(q, QUEUE_ORDERED_DO_PREFLUSH);
-		rq = &q->pre_flush_rq;
-	} else
-		skip |= QUEUE_ORDSEQ_PREFLUSH;
-
-	if ((q->ordered & QUEUE_ORDERED_BY_DRAIN) && queue_in_flight(q))
-		rq = NULL;
-	else
-		skip |= QUEUE_ORDSEQ_DRAIN;
-
-	*rqp = rq;
-
-	/*
-	 * Complete skipped sequences.  If whole sequence is complete,
-	 * return false to tell elevator that this request is gone.
-	 */
-	return !blk_ordered_complete_seq(q, skip, 0);
-}
-
-bool blk_do_ordered(struct request_queue *q, struct request **rqp)
-{
-	struct request *rq = *rqp;
-	const int is_barrier = rq->cmd_type == REQ_TYPE_FS &&
-				(rq->cmd_flags & REQ_HARDBARRIER);
-
-	if (!q->ordseq) {
-		if (!is_barrier)
-			return true;
-
-		if (q->next_ordered != QUEUE_ORDERED_NONE)
-			return start_ordered(q, rqp);
-		else {
-			/*
-			 * Queue ordering not supported.  Terminate
-			 * with prejudice.
-			 */
-			blk_dequeue_request(rq);
-			__blk_end_request_all(rq, -EOPNOTSUPP);
-			*rqp = NULL;
-			return false;
-		}
-	}
-
-	/*
-	 * Ordered sequence in progress
-	 */
-
-	/* Special requests are not subject to ordering rules. */
-	if (rq->cmd_type != REQ_TYPE_FS &&
-	    rq != &q->pre_flush_rq && rq != &q->post_flush_rq)
-		return true;
-
-	if (q->ordered & QUEUE_ORDERED_BY_TAG) {
-		/* Ordered by tag.  Blocking the next barrier is enough. */
-		if (is_barrier && rq != &q->bar_rq)
-			*rqp = NULL;
-	} else {
-		/* Ordered by draining.  Wait for turn. */
-		WARN_ON(blk_ordered_req_seq(rq) < blk_ordered_cur_seq(q));
-		if (blk_ordered_req_seq(rq) > blk_ordered_cur_seq(q))
-			*rqp = NULL;
-	}
-
-	return true;
-}
-
-static void bio_end_empty_barrier(struct bio *bio, int err)
-{
-	if (err) {
-		if (err == -EOPNOTSUPP)
-			set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
-		clear_bit(BIO_UPTODATE, &bio->bi_flags);
-	}
-	if (bio->bi_private)
-		complete(bio->bi_private);
-	bio_put(bio);
-}
-
-/**
- * blkdev_issue_flush - queue a flush
- * @bdev:	blockdev to issue flush for
- * @gfp_mask:	memory allocation flags (for bio_alloc)
- * @error_sector:	error sector
- * @flags:	BLKDEV_IFL_* flags to control behaviour
- *
- * Description:
- *    Issue a flush for the block device in question. Caller can supply
- *    room for storing the error offset in case of a flush error, if they
- *    wish to. If WAIT flag is not passed then caller may check only what
- *    request was pushed in some internal queue for later handling.
- */
-int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask,
-		sector_t *error_sector, unsigned long flags)
-{
-	DECLARE_COMPLETION_ONSTACK(wait);
-	struct request_queue *q;
-	struct bio *bio;
-	int ret = 0;
-
-	if (bdev->bd_disk == NULL)
-		return -ENXIO;
-
-	q = bdev_get_queue(bdev);
-	if (!q)
-		return -ENXIO;
-
-	/*
-	 * some block devices may not have their queue correctly set up here
-	 * (e.g. loop device without a backing file) and so issuing a flush
-	 * here will panic. Ensure there is a request function before issuing
-	 * the barrier.
-	 */
-	if (!q->make_request_fn)
-		return -ENXIO;
-
-	bio = bio_alloc(gfp_mask, 0);
-	bio->bi_end_io = bio_end_empty_barrier;
-	bio->bi_bdev = bdev;
-	if (test_bit(BLKDEV_WAIT, &flags))
-		bio->bi_private = &wait;
-
-	bio_get(bio);
-	submit_bio(WRITE_BARRIER, bio);
-	if (test_bit(BLKDEV_WAIT, &flags)) {
-		wait_for_completion(&wait);
-		/*
-		 * The driver must store the error location in ->bi_sector, if
-		 * it supports it. For non-stacked drivers, this should be
-		 * copied from blk_rq_pos(rq).
-		 */
-		if (error_sector)
-			*error_sector = bio->bi_sector;
-	}
-
-	if (bio_flagged(bio, BIO_EOPNOTSUPP))
-		ret = -EOPNOTSUPP;
-	else if (!bio_flagged(bio, BIO_UPTODATE))
-		ret = -EIO;
-
-	bio_put(bio);
-	return ret;
-}
-EXPORT_SYMBOL(blkdev_issue_flush);

block/blk-core.c

@@ -139,7 +139,7 @@ static void req_bio_endio(struct request *rq, struct bio *bio,
 {
 	struct request_queue *q = rq->q;
 
-	if (&q->bar_rq != rq) {
+	if (&q->flush_rq != rq) {
 		if (error)
 			clear_bit(BIO_UPTODATE, &bio->bi_flags);
 		else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
@@ -163,13 +163,12 @@ static void req_bio_endio(struct request *rq, struct bio *bio,
 		if (bio->bi_size == 0)
 			bio_endio(bio, error);
 	} else {
-
 		/*
-		 * Okay, this is the barrier request in progress, just
-		 * record the error;
+		 * Okay, this is the sequenced flush request in
+		 * progress, just record the error;
 		 */
-		if (error && !q->orderr)
-			q->orderr = error;
+		if (error && !q->flush_err)
+			q->flush_err = error;
 	}
 }
 
@@ -531,6 +530,7 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
 	init_timer(&q->unplug_timer);
 	setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q);
 	INIT_LIST_HEAD(&q->timeout_list);
+	INIT_LIST_HEAD(&q->pending_flushes);
 	INIT_WORK(&q->unplug_work, blk_unplug_work);
 
 	kobject_init(&q->kobj, &blk_queue_ktype);
@@ -1053,22 +1053,6 @@ void blk_insert_request(struct request_queue *q, struct request *rq,
 }
 EXPORT_SYMBOL(blk_insert_request);
 
-/*
- * add-request adds a request to the linked list.
- * queue lock is held and interrupts disabled, as we muck with the
- * request queue list.
- */
-static inline void add_request(struct request_queue *q, struct request *req)
-{
-	drive_stat_acct(req, 1);
-
-	/*
-	 * elevator indicated where it wants this request to be
-	 * inserted at elevator_merge time
-	 */
-	__elv_add_request(q, req, ELEVATOR_INSERT_SORT, 0);
-}
-
 static void part_round_stats_single(int cpu, struct hd_struct *part,
 				    unsigned long now)
 {
@@ -1217,13 +1201,16 @@ static int __make_request(struct request_queue *q, struct bio *bio)
 	const bool sync = !!(bio->bi_rw & REQ_SYNC);
 	const bool unplug = !!(bio->bi_rw & REQ_UNPLUG);
 	const unsigned long ff = bio->bi_rw & REQ_FAILFAST_MASK;
+	int where = ELEVATOR_INSERT_SORT;
 	int rw_flags;
 
-	if ((bio->bi_rw & REQ_HARDBARRIER) &&
-	    (q->next_ordered == QUEUE_ORDERED_NONE)) {
+	/* 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
@@ -1233,7 +1220,12 @@ static int __make_request(struct request_queue *q, struct bio *bio)
 
 	spin_lock_irq(q->queue_lock);
 
-	if (unlikely((bio->bi_rw & REQ_HARDBARRIER)) || elv_queue_empty(q))
+	if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) {
+		where = ELEVATOR_INSERT_FRONT;
+		goto get_rq;
+	}
+
+	if (elv_queue_empty(q))
 		goto get_rq;
 
 	el_ret = elv_merge(q, &req, bio);
@@ -1330,7 +1322,10 @@ static int __make_request(struct request_queue *q, struct bio *bio)
 		req->cpu = blk_cpu_to_group(smp_processor_id());
 	if (queue_should_plug(q) && elv_queue_empty(q))
 		blk_plug_device(q);
-	add_request(q, req);
+
+	/* insert the request into the elevator */
+	drive_stat_acct(req, 1);
+	__elv_add_request(q, req, where, 0);
 out:
 	if (unplug || !queue_should_plug(q))
 		__generic_unplug_device(q);
@@ -1530,6 +1525,19 @@ static inline void __generic_make_request(struct bio *bio)
 		if (bio_check_eod(bio, nr_sectors))
 			goto end_io;
 
+		/*
+		 * Filter flush bio's early so that make_request based
+		 * drivers without flush support don't have to worry
+		 * about them.
+		 */
+		if ((bio->bi_rw & (REQ_FLUSH | REQ_FUA)) && !q->flush_flags) {
+			bio->bi_rw &= ~(REQ_FLUSH | REQ_FUA);
+			if (!nr_sectors) {
+				err = 0;
+				goto end_io;
+			}
+		}
+
 		if ((bio->bi_rw & REQ_DISCARD) &&
 		    (!blk_queue_discard(q) ||
 		     ((bio->bi_rw & REQ_SECURE) &&
@@ -1794,11 +1802,11 @@ static void blk_account_io_completion(struct request *req, unsigned int bytes)
 static void blk_account_io_done(struct request *req)
 {
 	/*
-	 * Account IO completion.  bar_rq isn't accounted as a normal
-	 * IO on queueing nor completion.  Accounting the containing
-	 * request is enough.
+	 * Account IO completion.  flush_rq isn't accounted as a
+	 * normal IO on queueing nor completion.  Accounting the
+	 * containing request is enough.
 	 */
-	if (blk_do_io_stat(req) && req != &req->q->bar_rq) {
+	if (blk_do_io_stat(req) && req != &req->q->flush_rq) {
 		unsigned long duration = jiffies - req->start_time;
 		const int rw = rq_data_dir(req);
 		struct hd_struct *part;
@@ -2523,9 +2531,7 @@ EXPORT_SYMBOL_GPL(blk_rq_unprep_clone);
 static void __blk_rq_prep_clone(struct request *dst, struct request *src)
 {
 	dst->cpu = src->cpu;
-	dst->cmd_flags = (rq_data_dir(src) | REQ_NOMERGE);
-	if (src->cmd_flags & REQ_DISCARD)
-		dst->cmd_flags |= REQ_DISCARD;
+	dst->cmd_flags = (src->cmd_flags & REQ_CLONE_MASK) | REQ_NOMERGE;
 	dst->cmd_type = src->cmd_type;
 	dst->__sector = blk_rq_pos(src);
 	dst->__data_len = blk_rq_bytes(src);

block/blk-flush.c

@@ -0,0 +1,262 @@
+/*
+ * Functions to sequence FLUSH and FUA writes.
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/bio.h>
+#include <linux/blkdev.h>
+#include <linux/gfp.h>
+
+#include "blk.h"
+
+/* FLUSH/FUA sequences */
+enum {
+	QUEUE_FSEQ_STARTED	= (1 << 0), /* flushing in progress */
+	QUEUE_FSEQ_PREFLUSH	= (1 << 1), /* pre-flushing in progress */
+	QUEUE_FSEQ_DATA		= (1 << 2), /* data write in progress */
+	QUEUE_FSEQ_POSTFLUSH	= (1 << 3), /* post-flushing in progress */
+	QUEUE_FSEQ_DONE		= (1 << 4),
+};
+
+static struct request *queue_next_fseq(struct request_queue *q);
+
+unsigned blk_flush_cur_seq(struct request_queue *q)
+{
+	if (!q->flush_seq)
+		return 0;
+	return 1 << ffz(q->flush_seq);
+}
+
+static struct request *blk_flush_complete_seq(struct request_queue *q,
+					      unsigned seq, int error)
+{
+	struct request *next_rq = NULL;
+
+	if (error && !q->flush_err)
+		q->flush_err = error;
+
+	BUG_ON(q->flush_seq & seq);
+	q->flush_seq |= seq;
+
+	if (blk_flush_cur_seq(q) != QUEUE_FSEQ_DONE) {
+		/* not complete yet, queue the next flush sequence */
+		next_rq = queue_next_fseq(q);
+	} else {
+		/* complete this flush request */
+		__blk_end_request_all(q->orig_flush_rq, q->flush_err);
+		q->orig_flush_rq = NULL;
+		q->flush_seq = 0;
+
+		/* dispatch the next flush if there's one */
+		if (!list_empty(&q->pending_flushes)) {
+			next_rq = list_entry_rq(q->pending_flushes.next);
+			list_move(&next_rq->queuelist, &q->queue_head);
+		}
+	}
+	return next_rq;
+}
+
+static void blk_flush_complete_seq_end_io(struct request_queue *q,
+					  unsigned seq, int error)
+{
+	bool was_empty = elv_queue_empty(q);
+	struct request *next_rq;
+
+	next_rq = blk_flush_complete_seq(q, seq, error);
+
+	/*
+	 * Moving a request silently to empty queue_head may stall the
+	 * queue.  Kick the queue in those cases.
+	 */
+	if (was_empty && next_rq)
+		__blk_run_queue(q);
+}
+
+static void pre_flush_end_io(struct request *rq, int error)
+{
+	elv_completed_request(rq->q, rq);
+	blk_flush_complete_seq_end_io(rq->q, QUEUE_FSEQ_PREFLUSH, error);
+}
+
+static void flush_data_end_io(struct request *rq, int error)
+{
+	elv_completed_request(rq->q, rq);
+	blk_flush_complete_seq_end_io(rq->q, QUEUE_FSEQ_DATA, error);
+}
+
+static void post_flush_end_io(struct request *rq, int error)
+{
+	elv_completed_request(rq->q, rq);
+	blk_flush_complete_seq_end_io(rq->q, QUEUE_FSEQ_POSTFLUSH, error);
+}
+
+static void init_flush_request(struct request *rq, struct gendisk *disk)
+{
+	rq->cmd_type = REQ_TYPE_FS;
+	rq->cmd_flags = WRITE_FLUSH;
+	rq->rq_disk = disk;
+}
+
+static struct request *queue_next_fseq(struct request_queue *q)
+{
+	struct request *orig_rq = q->orig_flush_rq;
+	struct request *rq = &q->flush_rq;
+
+	blk_rq_init(q, rq);
+
+	switch (blk_flush_cur_seq(q)) {
+	case QUEUE_FSEQ_PREFLUSH:
+		init_flush_request(rq, orig_rq->rq_disk);
+		rq->end_io = pre_flush_end_io;
+		break;
+	case QUEUE_FSEQ_DATA:
+		init_request_from_bio(rq, orig_rq->bio);
+		/*
+		 * orig_rq->rq_disk may be different from
+		 * bio->bi_bdev->bd_disk if orig_rq got here through
+		 * remapping drivers.  Make sure rq->rq_disk points
+		 * to the same one as orig_rq.
+		 */
+		rq->rq_disk = orig_rq->rq_disk;
+		rq->cmd_flags &= ~(REQ_FLUSH | REQ_FUA);
+		rq->cmd_flags |= orig_rq->cmd_flags & (REQ_FLUSH | REQ_FUA);
+		rq->end_io = flush_data_end_io;
+		break;
+	case QUEUE_FSEQ_POSTFLUSH:
+		init_flush_request(rq, orig_rq->rq_disk);
+		rq->end_io = post_flush_end_io;
+		break;
+	default:
+		BUG();
+	}
+
+	elv_insert(q, rq, ELEVATOR_INSERT_FRONT);
+	return rq;
+}
+
+struct request *blk_do_flush(struct request_queue *q, struct request *rq)
+{
+	unsigned int fflags = q->flush_flags; /* may change, cache it */
+	bool has_flush = fflags & REQ_FLUSH, has_fua = fflags & REQ_FUA;
+	bool do_preflush = has_flush && (rq->cmd_flags & REQ_FLUSH);
+	bool do_postflush = has_flush && !has_fua && (rq->cmd_flags & REQ_FUA);
+	unsigned skip = 0;
+
+	/*
+	 * Special case.  If there's data but flush is not necessary,
+	 * the request can be issued directly.
+	 *
+	 * Flush w/o data should be able to be issued directly too but
+	 * currently some drivers assume that rq->bio contains
+	 * non-zero data if it isn't NULL and empty FLUSH requests
+	 * getting here usually have bio's without data.
+	 */
+	if (blk_rq_sectors(rq) && !do_preflush && !do_postflush) {
+		rq->cmd_flags &= ~REQ_FLUSH;
+		if (!has_fua)
+			rq->cmd_flags &= ~REQ_FUA;
+		return rq;
+	}
+
+	/*
+	 * Sequenced flushes can't be processed in parallel.  If
+	 * another one is already in progress, queue for later
+	 * processing.
+	 */
+	if (q->flush_seq) {
+		list_move_tail(&rq->queuelist, &q->pending_flushes);
+		return NULL;
+	}
+
+	/*
+	 * Start a new flush sequence
+	 */
+	q->flush_err = 0;
+	q->flush_seq |= QUEUE_FSEQ_STARTED;
+
+	/* adjust FLUSH/FUA of the original request and stash it away */
+	rq->cmd_flags &= ~REQ_FLUSH;
+	if (!has_fua)
+		rq->cmd_flags &= ~REQ_FUA;
+	blk_dequeue_request(rq);
+	q->orig_flush_rq = rq;
+
+	/* skip unneded sequences and return the first one */
+	if (!do_preflush)
+		skip |= QUEUE_FSEQ_PREFLUSH;
+	if (!blk_rq_sectors(rq))
+		skip |= QUEUE_FSEQ_DATA;
+	if (!do_postflush)
+		skip |= QUEUE_FSEQ_POSTFLUSH;
+	return blk_flush_complete_seq(q, skip, 0);
+}
+
+static void bio_end_flush(struct bio *bio, int err)
+{
+	if (err)
+		clear_bit(BIO_UPTODATE, &bio->bi_flags);
+	if (bio->bi_private)
+		complete(bio->bi_private);
+	bio_put(bio);
+}
+
+/**
+ * blkdev_issue_flush - queue a flush
+ * @bdev:	blockdev to issue flush for
+ * @gfp_mask:	memory allocation flags (for bio_alloc)
+ * @error_sector:	error sector
+ *
+ * Description:
+ *    Issue a flush for the block device in question. Caller can supply
+ *    room for storing the error offset in case of a flush error, if they
+ *    wish to. If WAIT flag is not passed then caller may check only what
+ *    request was pushed in some internal queue for later handling.
+ */
+int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask,
+		sector_t *error_sector)
+{
+	DECLARE_COMPLETION_ONSTACK(wait);
+	struct request_queue *q;
+	struct bio *bio;
+	int ret = 0;
+
+	if (bdev->bd_disk == NULL)
+		return -ENXIO;
+
+	q = bdev_get_queue(bdev);
+	if (!q)
+		return -ENXIO;
+
+	/*
+	 * some block devices may not have their queue correctly set up here
+	 * (e.g. loop device without a backing file) and so issuing a flush
+	 * here will panic. Ensure there is a request function before issuing
+	 * the flush.
+	 */
+	if (!q->make_request_fn)
+		return -ENXIO;
+
+	bio = bio_alloc(gfp_mask, 0);
+	bio->bi_end_io = bio_end_flush;
+	bio->bi_bdev = bdev;
+	bio->bi_private = &wait;
+
+	bio_get(bio);
+	submit_bio(WRITE_FLUSH, bio);
+	wait_for_completion(&wait);
+
+	/*
+	 * The driver must store the error location in ->bi_sector, if
+	 * it supports it. For non-stacked drivers, this should be
+	 * copied from blk_rq_pos(rq).
+	 */
+	if (error_sector)
+               *error_sector = bio->bi_sector;
+
+	if (!bio_flagged(bio, BIO_UPTODATE))
+		ret = -EIO;
+
+	bio_put(bio);
+	return ret;
+}
+EXPORT_SYMBOL(blkdev_issue_flush);

block/blk-lib.c

@@ -39,8 +39,7 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 {
 	DECLARE_COMPLETION_ONSTACK(wait);
 	struct request_queue *q = bdev_get_queue(bdev);
-	int type = flags & BLKDEV_IFL_BARRIER ?
-		DISCARD_BARRIER : DISCARD_NOBARRIER;
+	int type = REQ_WRITE | REQ_DISCARD;
 	unsigned int max_discard_sectors;
 	struct bio *bio;
 	int ret = 0;
@@ -62,10 +61,10 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 		max_discard_sectors &= ~(disc_sects - 1);
 	}
 
-	if (flags & BLKDEV_IFL_SECURE) {
+	if (flags & BLKDEV_DISCARD_SECURE) {
 		if (!blk_queue_secdiscard(q))
 			return -EOPNOTSUPP;
-		type |= DISCARD_SECURE;
+		type |= REQ_SECURE;
 	}
 
 	while (nr_sects && !ret) {
@@ -78,8 +77,7 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 		bio->bi_sector = sector;
 		bio->bi_end_io = blkdev_discard_end_io;
 		bio->bi_bdev = bdev;
-		if (flags & BLKDEV_IFL_WAIT)
-			bio->bi_private = &wait;
+		bio->bi_private = &wait;
 
 		if (nr_sects > max_discard_sectors) {
 			bio->bi_size = max_discard_sectors << 9;
@@ -93,8 +91,7 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 		bio_get(bio);
 		submit_bio(type, bio);
 
-		if (flags & BLKDEV_IFL_WAIT)
-			wait_for_completion(&wait);
+		wait_for_completion(&wait);
 
 		if (bio_flagged(bio, BIO_EOPNOTSUPP))
 			ret = -EOPNOTSUPP;
@@ -140,7 +137,6 @@ static void bio_batch_end_io(struct bio *bio, int err)
  * @sector:	start sector
  * @nr_sects:	number of sectors to write
  * @gfp_mask:	memory allocation flags (for bio_alloc)
- * @flags:	BLKDEV_IFL_* flags to control behaviour
  *
  * Description:
  *  Generate and issue number of bios with zerofiled pages.
@@ -149,7 +145,7 @@ static void bio_batch_end_io(struct bio *bio, int err)
  */
 
 int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
-			sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)
+			sector_t nr_sects, gfp_t gfp_mask)
 {
 	int ret;
 	struct bio *bio;
@@ -162,12 +158,6 @@ int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
 	bb.wait = &wait;
 	bb.end_io = NULL;
 
-	if (flags & BLKDEV_IFL_BARRIER) {
-		/* issue async barrier before the data */
-		ret = blkdev_issue_flush(bdev, gfp_mask, NULL, 0);
-		if (ret)
-			return ret;
-	}
 submit:
 	ret = 0;
 	while (nr_sects != 0) {
@@ -181,8 +171,7 @@ int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
 		bio->bi_sector = sector;
 		bio->bi_bdev   = bdev;
 		bio->bi_end_io = bio_batch_end_io;
-		if (flags & BLKDEV_IFL_WAIT)
-			bio->bi_private = &bb;
+		bio->bi_private = &bb;
 
 		while (nr_sects != 0) {
 			sz = min((sector_t) PAGE_SIZE >> 9 , nr_sects);
@@ -199,18 +188,10 @@ int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
 		issued++;
 		submit_bio(WRITE, bio);
 	}
-	/*
-	 * When all data bios are in flight. Send final barrier if requeted.
-	 */
-	if (nr_sects == 0 && flags & BLKDEV_IFL_BARRIER)
-		ret = blkdev_issue_flush(bdev, gfp_mask, NULL,
-					flags & BLKDEV_IFL_WAIT);
-
 
-	if (flags & BLKDEV_IFL_WAIT)
-		/* Wait for bios in-flight */
-		while ( issued != atomic_read(&bb.done))
-			wait_for_completion(&wait);
+	/* Wait for bios in-flight */
+	while (issued != atomic_read(&bb.done))
+		wait_for_completion(&wait);
 
 	if (!test_bit(BIO_UPTODATE, &bb.flags))
 		/* One of bios in the batch was completed with error.*/

block/blk-settings.c

@@ -792,6 +792,26 @@ void blk_queue_update_dma_alignment(struct request_queue *q, int mask)
 }
 EXPORT_SYMBOL(blk_queue_update_dma_alignment);
 
+/**
+ * blk_queue_flush - configure queue's cache flush capability
+ * @q:		the request queue for the device
+ * @flush:	0, REQ_FLUSH or REQ_FLUSH | REQ_FUA
+ *
+ * Tell block layer cache flush capability of @q.  If it supports
+ * flushing, REQ_FLUSH should be set.  If it supports bypassing
+ * write cache for individual writes, REQ_FUA should be set.
+ */
+void blk_queue_flush(struct request_queue *q, unsigned int flush)
+{
+	WARN_ON_ONCE(flush & ~(REQ_FLUSH | REQ_FUA));
+
+	if (WARN_ON_ONCE(!(flush & REQ_FLUSH) && (flush & REQ_FUA)))
+		flush &= ~REQ_FUA;
+
+	q->flush_flags = flush & (REQ_FLUSH | REQ_FUA);
+}
+EXPORT_SYMBOL_GPL(blk_queue_flush);
+
 static int __init blk_settings_init(void)
 {
 	blk_max_low_pfn = max_low_pfn - 1;

block/blk.h

@@ -51,6 +51,8 @@ static inline void blk_clear_rq_complete(struct request *rq)
  */
 #define ELV_ON_HASH(rq)		(!hlist_unhashed(&(rq)->hash))
 
+struct request *blk_do_flush(struct request_queue *q, struct request *rq);
+
 static inline struct request *__elv_next_request(struct request_queue *q)
 {
 	struct request *rq;
@@ -58,7 +60,11 @@ static inline struct request *__elv_next_request(struct request_queue *q)
 	while (1) {
 		while (!list_empty(&q->queue_head)) {
 			rq = list_entry_rq(q->queue_head.next);
-			if (blk_do_ordered(q, &rq))
+			if (!(rq->cmd_flags & (REQ_FLUSH | REQ_FUA)) ||
+			    rq == &q->flush_rq)
+				return rq;
+			rq = blk_do_flush(q, rq);
+			if (rq)
 				return rq;
 		}
 

block/elevator.c

@@ -617,8 +617,6 @@ void elv_quiesce_end(struct request_queue *q)
 
 void elv_insert(struct request_queue *q, struct request *rq, int where)
 {
-	struct list_head *pos;
-	unsigned ordseq;
 	int unplug_it = 1;
 
 	trace_block_rq_insert(q, rq);
@@ -626,9 +624,16 @@ void elv_insert(struct request_queue *q, struct request *rq, int where)
 	rq->q = q;
 
 	switch (where) {
+	case ELEVATOR_INSERT_REQUEUE:
+		/*
+		 * Most requeues happen because of a busy condition,
+		 * don't force unplug of the queue for that case.
+		 * Clear unplug_it and fall through.
+		 */
+		unplug_it = 0;
+
 	case ELEVATOR_INSERT_FRONT:
 		rq->cmd_flags |= REQ_SOFTBARRIER;
-
 		list_add(&rq->queuelist, &q->queue_head);
 		break;
 
@@ -668,36 +673,6 @@ void elv_insert(struct request_queue *q, struct request *rq, int where)
 		q->elevator->ops->elevator_add_req_fn(q, rq);
 		break;
 
-	case ELEVATOR_INSERT_REQUEUE:
-		/*
-		 * If ordered flush isn't in progress, we do front
-		 * insertion; otherwise, requests should be requeued
-		 * in ordseq order.
-		 */
-		rq->cmd_flags |= REQ_SOFTBARRIER;
-
-		/*
-		 * Most requeues happen because of a busy condition,
-		 * don't force unplug of the queue for that case.
-		 */
-		unplug_it = 0;
-
-		if (q->ordseq == 0) {
-			list_add(&rq->queuelist, &q->queue_head);
-			break;
-		}
-
-		ordseq = blk_ordered_req_seq(rq);
-
-		list_for_each(pos, &q->queue_head) {
-			struct request *pos_rq = list_entry_rq(pos);
-			if (ordseq <= blk_ordered_req_seq(pos_rq))
-				break;
-		}
-
-		list_add_tail(&rq->queuelist, pos);
-		break;
-
 	default:
 		printk(KERN_ERR "%s: bad insertion point %d\n",
 		       __func__, where);
@@ -716,26 +691,8 @@ 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 (q->ordcolor)
-		rq->cmd_flags |= REQ_ORDERED_COLOR;
-
 	if (rq->cmd_flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) {
-		/*
-		 * toggle ordered color
-		 */
-		if (rq->cmd_flags & REQ_HARDBARRIER)
-			q->ordcolor ^= 1;
-
-		/*
-		 * barriers implicitly indicate back insertion
-		 */
-		if (where == ELEVATOR_INSERT_SORT)
-			where = ELEVATOR_INSERT_BACK;
-
-		/*
-		 * this request is scheduling boundary, update
-		 * end_sector
-		 */
+		/* barriers are scheduling boundary, update end_sector */
 		if (rq->cmd_type == REQ_TYPE_FS ||
 		    (rq->cmd_flags & REQ_DISCARD)) {
 			q->end_sector = rq_end_sector(rq);
@@ -855,24 +812,6 @@ void elv_completed_request(struct request_queue *q, struct request *rq)
 		    e->ops->elevator_completed_req_fn)
 			e->ops->elevator_completed_req_fn(q, rq);
 	}
-
-	/*
-	 * Check if the queue is waiting for fs requests to be
-	 * drained for flush sequence.
-	 */
-	if (unlikely(q->ordseq)) {
-		struct request *next = NULL;
-
-		if (!list_empty(&q->queue_head))
-			next = list_entry_rq(q->queue_head.next);
-
-		if (!queue_in_flight(q) &&
-		    blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN &&
-		    (!next || blk_ordered_req_seq(next) > QUEUE_ORDSEQ_DRAIN)) {
-			blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0);
-			__blk_run_queue(q);
-		}
-	}
 }
 
 #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr)

block/ioctl.c

@@ -116,7 +116,7 @@ static int blkdev_reread_part(struct block_device *bdev)
 static int blk_ioctl_discard(struct block_device *bdev, uint64_t start,
 			     uint64_t len, int secure)
 {
-	unsigned long flags = BLKDEV_IFL_WAIT;
+	unsigned long flags = 0;
 
 	if (start & 511)
 		return -EINVAL;
@@ -128,7 +128,7 @@ static int blk_ioctl_discard(struct block_device *bdev, uint64_t start,
 	if (start + len > (bdev->bd_inode->i_size >> 9))
 		return -EINVAL;
 	if (secure)
-		flags |= BLKDEV_IFL_SECURE;
+		flags |= BLKDEV_DISCARD_SECURE;
 	return blkdev_issue_discard(bdev, start, len, GFP_KERNEL, flags);
 }
 

drivers/block/brd.c

@@ -483,7 +483,6 @@ static struct brd_device *brd_alloc(int i)
 	if (!brd->brd_queue)
 		goto out_free_dev;
 	blk_queue_make_request(brd->brd_queue, brd_make_request);
-	blk_queue_ordered(brd->brd_queue, QUEUE_ORDERED_TAG);
 	blk_queue_max_hw_sectors(brd->brd_queue, 1024);
 	blk_queue_bounce_limit(brd->brd_queue, BLK_BOUNCE_ANY);
 

drivers/block/drbd/drbd_int.h

@@ -2409,8 +2409,7 @@ static inline void drbd_md_flush(struct drbd_conf *mdev)
 	if (test_bit(MD_NO_BARRIER, &mdev->flags))
 		return;
 
-	r = blkdev_issue_flush(mdev->ldev->md_bdev, GFP_KERNEL, NULL,
-			BLKDEV_IFL_WAIT);
+	r = blkdev_issue_flush(mdev->ldev->md_bdev, GFP_KERNEL, NULL);
 	if (r) {
 		set_bit(MD_NO_BARRIER, &mdev->flags);
 		dev_err(DEV, "meta data flush failed with status %d, disabling md-flushes\n", r);

drivers/block/drbd/drbd_receiver.c

@@ -987,7 +987,7 @@ static enum finish_epoch drbd_flush_after_epoch(struct drbd_conf *mdev, struct d
 
 	if (mdev->write_ordering >= WO_bdev_flush && get_ldev(mdev)) {
 		rv = blkdev_issue_flush(mdev->ldev->backing_bdev, GFP_KERNEL,
-					NULL, BLKDEV_IFL_WAIT);
+					NULL);
 		if (rv) {
 			dev_err(DEV, "local disk flush failed with status %d\n", rv);
 			/* would rather check on EOPNOTSUPP, but that is not reliable.

drivers/block/loop.c

@@ -479,17 +479,17 @@ static int do_bio_filebacked(struct loop_device *lo, struct bio *bio)
 	pos = ((loff_t) bio->bi_sector << 9) + lo->lo_offset;
 
 	if (bio_rw(bio) == WRITE) {
-		bool barrier = !!(bio->bi_rw & REQ_HARDBARRIER);
 		struct file *file = lo->lo_backing_file;
 
-		if (barrier) {
-			if (unlikely(!file->f_op->fsync)) {
-				ret = -EOPNOTSUPP;
-				goto out;
-			}
+		/* 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)) {
+			if (unlikely(ret && ret != -EINVAL)) {
 				ret = -EIO;
 				goto out;
 			}
@@ -497,9 +497,9 @@ static int do_bio_filebacked(struct loop_device *lo, struct bio *bio)
 
 		ret = lo_send(lo, bio, pos);
 
-		if (barrier && !ret) {
+		if ((bio->bi_rw & REQ_FUA) && !ret) {
 			ret = vfs_fsync(file, 0);
-			if (unlikely(ret))
+			if (unlikely(ret && ret != -EINVAL))
 				ret = -EIO;
 		}
 	} else
@@ -931,7 +931,7 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
 	lo->lo_queue->unplug_fn = loop_unplug;
 
 	if (!(lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
-		blk_queue_ordered(lo->lo_queue, QUEUE_ORDERED_DRAIN);
+		blk_queue_flush(lo->lo_queue, REQ_FLUSH);
 
 	set_capacity(lo->lo_disk, size);
 	bd_set_size(bdev, size << 9);

drivers/block/osdblk.c

@@ -310,8 +310,7 @@ static void osdblk_rq_fn(struct request_queue *q)
 			break;
 
 		/* filter out block requests we don't understand */
-		if (rq->cmd_type != REQ_TYPE_FS &&
-		    !(rq->cmd_flags & REQ_HARDBARRIER)) {
+		if (rq->cmd_type != REQ_TYPE_FS) {
 			blk_end_request_all(rq, 0);
 			continue;
 		}
@@ -439,7 +438,7 @@ static int osdblk_init_disk(struct osdblk_device *osdev)
 	blk_queue_stack_limits(q, osd_request_queue(osdev->osd));
 
 	blk_queue_prep_rq(q, blk_queue_start_tag);
-	blk_queue_ordered(q, QUEUE_ORDERED_DRAIN_FLUSH);
+	blk_queue_flush(q, REQ_FLUSH);
 
 	disk->queue = q;
 

drivers/block/pktcdvd.c

@@ -753,7 +753,6 @@ static int pkt_generic_packet(struct pktcdvd_device *pd, struct packet_command *
 
 	rq->timeout = 60*HZ;
 	rq->cmd_type = REQ_TYPE_BLOCK_PC;
-	rq->cmd_flags |= REQ_HARDBARRIER;
 	if (cgc->quiet)
 		rq->cmd_flags |= REQ_QUIET;
 

drivers/block/ps3disk.c

@@ -468,7 +468,7 @@ static int __devinit ps3disk_probe(struct ps3_system_bus_device *_dev)
 	blk_queue_dma_alignment(queue, dev->blk_size-1);
 	blk_queue_logical_block_size(queue, dev->blk_size);
 
-	blk_queue_ordered(queue, QUEUE_ORDERED_DRAIN_FLUSH);
+	blk_queue_flush(queue, REQ_FLUSH);
 
 	blk_queue_max_segments(queue, -1);
 	blk_queue_max_segment_size(queue, dev->bounce_size);

drivers/block/virtio_blk.c

@@ -127,9 +127,6 @@ static bool do_req(struct request_queue *q, struct virtio_blk *vblk,
 		}
 	}
 
-	if (vbr->req->cmd_flags & REQ_HARDBARRIER)
-		vbr->out_hdr.type |= VIRTIO_BLK_T_BARRIER;
-
 	sg_set_buf(&vblk->sg[out++], &vbr->out_hdr, sizeof(vbr->out_hdr));
 
 	/*
@@ -379,31 +376,9 @@ static int __devinit virtblk_probe(struct virtio_device *vdev)
 	vblk->disk->driverfs_dev = &vdev->dev;
 	index++;
 
-	if (virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH)) {
-		/*
-		 * If the FLUSH feature is supported we do have support for
-		 * flushing a volatile write cache on the host.  Use that
-		 * to implement write barrier support.
-		 */
-		blk_queue_ordered(q, QUEUE_ORDERED_DRAIN_FLUSH);
-	} else if (virtio_has_feature(vdev, VIRTIO_BLK_F_BARRIER)) {
-		/*
-		 * If the BARRIER feature is supported the host expects us
-		 * to order request by tags.  This implies there is not
-		 * volatile write cache on the host, and that the host
-		 * never re-orders outstanding I/O.  This feature is not
-		 * useful for real life scenarious and deprecated.
-		 */
-		blk_queue_ordered(q, QUEUE_ORDERED_TAG);
-	} else {
-		/*
-		 * If the FLUSH feature is not supported we must assume that
-		 * the host does not perform any kind of volatile write
-		 * caching. We still need to drain the queue to provider
-		 * proper barrier semantics.
-		 */
-		blk_queue_ordered(q, QUEUE_ORDERED_DRAIN);
-	}
+	/* configure queue flush support */
+	if (virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH))
+		blk_queue_flush(q, REQ_FLUSH);
 
 	/* If disk is read-only in the host, the guest should obey */
 	if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO))
@@ -522,9 +497,9 @@ static const struct virtio_device_id id_table[] = {
 };
 
 static unsigned int features[] = {
-	VIRTIO_BLK_F_BARRIER, VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX,
-	VIRTIO_BLK_F_GEOMETRY, VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE,
-	VIRTIO_BLK_F_SCSI, VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY
+	VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY,
+	VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE, VIRTIO_BLK_F_SCSI,
+	VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY
 };
 
 /*

drivers/block/xen-blkfront.c

@@ -96,7 +96,7 @@ struct blkfront_info
 	struct gnttab_free_callback callback;
 	struct blk_shadow shadow[BLK_RING_SIZE];
 	unsigned long shadow_free;
-	int feature_barrier;
+	unsigned int feature_flush;
 	int is_ready;
 };
 
@@ -419,26 +419,12 @@ static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size)
 }
 
 
-static int xlvbd_barrier(struct blkfront_info *info)
+static void xlvbd_flush(struct blkfront_info *info)
 {
-	int err;
-	const char *barrier;
-
-	switch (info->feature_barrier) {
-	case QUEUE_ORDERED_DRAIN:	barrier = "enabled (drain)"; break;
-	case QUEUE_ORDERED_TAG:		barrier = "enabled (tag)"; break;
-	case QUEUE_ORDERED_NONE:	barrier = "disabled"; break;
-	default:			return -EINVAL;
-	}
-
-	err = blk_queue_ordered(info->rq, info->feature_barrier);
-
-	if (err)
-		return err;
-
+	blk_queue_flush(info->rq, info->feature_flush);
 	printk(KERN_INFO "blkfront: %s: barriers %s\n",
-	       info->gd->disk_name, barrier);
-	return 0;
+	       info->gd->disk_name,
+	       info->feature_flush ? "enabled" : "disabled");
 }
 
 
@@ -517,7 +503,7 @@ static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
 	info->rq = gd->queue;
 	info->gd = gd;
 
-	xlvbd_barrier(info);
+	xlvbd_flush(info);
 
 	if (vdisk_info & VDISK_READONLY)
 		set_disk_ro(gd, 1);
@@ -663,8 +649,8 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id)
 				printk(KERN_WARNING "blkfront: %s: write barrier op failed\n",
 				       info->gd->disk_name);
 				error = -EOPNOTSUPP;
-				info->feature_barrier = QUEUE_ORDERED_NONE;
-				xlvbd_barrier(info);
+				info->feature_flush = 0;
+				xlvbd_flush(info);
 			}
 			/* fall through */
 		case BLKIF_OP_READ:
@@ -1077,20 +1063,20 @@ static void blkfront_connect(struct blkfront_info *info)
 	/*
 	 * If there's no "feature-barrier" defined, then it means
 	 * we're dealing with a very old backend which writes
-	 * synchronously; draining will do what needs to get done.
+	 * synchronously; nothing to do.
 	 *
-	 * If there are barriers, then we can do full queued writes
-	 * with tagged barriers.
-	 *
-	 * If barriers are not supported, then there's no much we can
-	 * do, so just set ordering to NONE.
+	 * If there are barriers, then we use flush.
 	 */
-	if (err)
-		info->feature_barrier = QUEUE_ORDERED_DRAIN;
-	else if (barrier)
-		info->feature_barrier = QUEUE_ORDERED_TAG;
-	else
-		info->feature_barrier = QUEUE_ORDERED_NONE;
+	info->feature_flush = 0;
+
+	/*
+	 * The driver doesn't properly handled empty flushes, so
+	 * lets disable barrier support for now.
+	 */
+#if 0
+	if (!err && barrier)
+		info->feature_flush = REQ_FLUSH;
+#endif
 
 	err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size);
 	if (err) {

drivers/ide/ide-disk.c

@@ -516,10 +516,10 @@ static int ide_do_setfeature(ide_drive_t *drive, u8 feature, u8 nsect)
 	return ide_no_data_taskfile(drive, &cmd);
 }
 
-static void update_ordered(ide_drive_t *drive)
+static void update_flush(ide_drive_t *drive)
 {
 	u16 *id = drive->id;
-	unsigned ordered = QUEUE_ORDERED_NONE;
+	unsigned flush = 0;
 
 	if (drive->dev_flags & IDE_DFLAG_WCACHE) {
 		unsigned long long capacity;
@@ -543,13 +543,12 @@ static void update_ordered(ide_drive_t *drive)
 		       drive->name, barrier ? "" : "not ");
 
 		if (barrier) {
-			ordered = QUEUE_ORDERED_DRAIN_FLUSH;
+			flush = REQ_FLUSH;
 			blk_queue_prep_rq(drive->queue, idedisk_prep_fn);
 		}
-	} else
-		ordered = QUEUE_ORDERED_DRAIN;
+	}
 
-	blk_queue_ordered(drive->queue, ordered);
+	blk_queue_flush(drive->queue, flush);
 }
 
 ide_devset_get_flag(wcache, IDE_DFLAG_WCACHE);
@@ -572,7 +571,7 @@ static int set_wcache(ide_drive_t *drive, int arg)
 		}
 	}
 
-	update_ordered(drive);
+	update_flush(drive);
 
 	return err;
 }

drivers/ide/ide-io.c

@@ -441,19 +441,6 @@ void do_ide_request(struct request_queue *q)
 	struct request	*rq = NULL;
 	ide_startstop_t	startstop;
 
-	/*
-	 * drive is doing pre-flush, ordered write, post-flush sequence. even
-	 * though that is 3 requests, it must be seen as a single transaction.
-	 * we must not preempt this drive until that is complete
-	 */
-	if (blk_queue_flushing(q))
-		/*
-		 * small race where queue could get replugged during
-		 * the 3-request flush cycle, just yank the plug since
-		 * we want it to finish asap
-		 */
-		blk_remove_plug(q);
-
 	spin_unlock_irq(q->queue_lock);
 
 	/* HLD do_request() callback might sleep, make sure it's okay */

drivers/md/dm-crypt.c

@@ -1278,7 +1278,7 @@ static int crypt_map(struct dm_target *ti, struct bio *bio,
 	struct dm_crypt_io *io;
 	struct crypt_config *cc;
 
-	if (unlikely(bio_empty_barrier(bio))) {
+	if (bio->bi_rw & REQ_FLUSH) {
 		cc = ti->private;
 		bio->bi_bdev = cc->dev->bdev;
 		return DM_MAPIO_REMAPPED;

drivers/md/dm-io.c

@@ -31,7 +31,6 @@ struct dm_io_client {
  */
 struct io {
 	unsigned long error_bits;
-	unsigned long eopnotsupp_bits;
 	atomic_t count;
 	struct task_struct *sleeper;
 	struct dm_io_client *client;
@@ -130,11 +129,8 @@ static void retrieve_io_and_region_from_bio(struct bio *bio, struct io **io,
  *---------------------------------------------------------------*/
 static void dec_count(struct io *io, unsigned int region, int error)
 {
-	if (error) {
+	if (error)
 		set_bit(region, &io->error_bits);
-		if (error == -EOPNOTSUPP)
-			set_bit(region, &io->eopnotsupp_bits);
-	}
 
 	if (atomic_dec_and_test(&io->count)) {
 		if (io->sleeper)
@@ -310,8 +306,8 @@ static void do_region(int rw, unsigned region, struct dm_io_region *where,
 	sector_t remaining = where->count;
 
 	/*
-	 * where->count may be zero if rw holds a write barrier and we
-	 * need to send a zero-sized barrier.
+	 * where->count may be zero if rw holds a flush and we need to
+	 * send a zero-sized flush.
 	 */
 	do {
 		/*
@@ -364,7 +360,7 @@ static void dispatch_io(int rw, unsigned int num_regions,
 	 */
 	for (i = 0; i < num_regions; i++) {
 		*dp = old_pages;
-		if (where[i].count || (rw & REQ_HARDBARRIER))
+		if (where[i].count || (rw & REQ_FLUSH))
 			do_region(rw, i, where + i, dp, io);
 	}
 
@@ -393,9 +389,7 @@ static int sync_io(struct dm_io_client *client, unsigned int num_regions,
 		return -EIO;
 	}
 
-retry:
 	io->error_bits = 0;
-	io->eopnotsupp_bits = 0;
 	atomic_set(&io->count, 1); /* see dispatch_io() */
 	io->sleeper = current;
 	io->client = client;
@@ -412,11 +406,6 @@ static int sync_io(struct dm_io_client *client, unsigned int num_regions,
 	}
 	set_current_state(TASK_RUNNING);
 
-	if (io->eopnotsupp_bits && (rw & REQ_HARDBARRIER)) {
-		rw &= ~REQ_HARDBARRIER;
-		goto retry;
-	}
-
 	if (error_bits)
 		*error_bits = io->error_bits;
 
@@ -437,7 +426,6 @@ static int async_io(struct dm_io_client *client, unsigned int num_regions,
 
 	io = mempool_alloc(client->pool, GFP_NOIO);
 	io->error_bits = 0;
-	io->eopnotsupp_bits = 0;
 	atomic_set(&io->count, 1); /* see dispatch_io() */
 	io->sleeper = NULL;
 	io->client = client;

drivers/md/dm-log.c

@@ -300,7 +300,7 @@ static int flush_header(struct log_c *lc)
 		.count = 0,
 	};
 
-	lc->io_req.bi_rw = WRITE_BARRIER;
+	lc->io_req.bi_rw = WRITE_FLUSH;
 
 	return dm_io(&lc->io_req, 1, &null_location, NULL);
 }

drivers/md/dm-raid1.c

@@ -259,7 +259,7 @@ static int mirror_flush(struct dm_target *ti)
 	struct dm_io_region io[ms->nr_mirrors];
 	struct mirror *m;
 	struct dm_io_request io_req = {
-		.bi_rw = WRITE_BARRIER,
+		.bi_rw = WRITE_FLUSH,
 		.mem.type = DM_IO_KMEM,
 		.mem.ptr.bvec = NULL,
 		.client = ms->io_client,
@@ -629,7 +629,7 @@ static void do_write(struct mirror_set *ms, struct bio *bio)
 	struct dm_io_region io[ms->nr_mirrors], *dest = io;
 	struct mirror *m;
 	struct dm_io_request io_req = {
-		.bi_rw = WRITE | (bio->bi_rw & WRITE_BARRIER),
+		.bi_rw = WRITE | (bio->bi_rw & WRITE_FLUSH_FUA),
 		.mem.type = DM_IO_BVEC,
 		.mem.ptr.bvec = bio->bi_io_vec + bio->bi_idx,
 		.notify.fn = write_callback,
@@ -670,7 +670,7 @@ static void do_writes(struct mirror_set *ms, struct bio_list *writes)
 	bio_list_init(&requeue);
 
 	while ((bio = bio_list_pop(writes))) {
-		if (unlikely(bio_empty_barrier(bio))) {
+		if (bio->bi_rw & REQ_FLUSH) {
 			bio_list_add(&sync, bio);
 			continue;
 		}
@@ -1203,7 +1203,7 @@ static int mirror_end_io(struct dm_target *ti, struct bio *bio,
 	 * We need to dec pending if this was a write.
 	 */
 	if (rw == WRITE) {
-		if (likely(!bio_empty_barrier(bio)))
+		if (!(bio->bi_rw & REQ_FLUSH))
 			dm_rh_dec(ms->rh, map_context->ll);
 		return error;
 	}

drivers/md/dm-region-hash.c

@@ -81,9 +81,9 @@ struct dm_region_hash {
 	struct list_head failed_recovered_regions;
 
 	/*
-	 * If there was a barrier failure no regions can be marked clean.
+	 * If there was a flush failure no regions can be marked clean.
 	 */
-	int barrier_failure;
+	int flush_failure;
 
 	void *context;
 	sector_t target_begin;
@@ -217,7 +217,7 @@ struct dm_region_hash *dm_region_hash_create(
 	INIT_LIST_HEAD(&rh->quiesced_regions);
 	INIT_LIST_HEAD(&rh->recovered_regions);
 	INIT_LIST_HEAD(&rh->failed_recovered_regions);
-	rh->barrier_failure = 0;
+	rh->flush_failure = 0;
 
 	rh->region_pool = mempool_create_kmalloc_pool(MIN_REGIONS,
 						      sizeof(struct dm_region));
@@ -399,8 +399,8 @@ void dm_rh_mark_nosync(struct dm_region_hash *rh, struct bio *bio)
 	region_t region = dm_rh_bio_to_region(rh, bio);
 	int recovering = 0;
 
-	if (bio_empty_barrier(bio)) {
-		rh->barrier_failure = 1;
+	if (bio->bi_rw & REQ_FLUSH) {
+		rh->flush_failure = 1;
 		return;
 	}
 
@@ -524,7 +524,7 @@ void dm_rh_inc_pending(struct dm_region_hash *rh, struct bio_list *bios)
 	struct bio *bio;
 
 	for (bio = bios->head; bio; bio = bio->bi_next) {
-		if (bio_empty_barrier(bio))
+		if (bio->bi_rw & REQ_FLUSH)
 			continue;
 		rh_inc(rh, dm_rh_bio_to_region(rh, bio));
 	}
@@ -555,9 +555,9 @@ void dm_rh_dec(struct dm_region_hash *rh, region_t region)
 		 */
 
 		/* do nothing for DM_RH_NOSYNC */
-		if (unlikely(rh->barrier_failure)) {
+		if (unlikely(rh->flush_failure)) {
 			/*
-			 * If a write barrier failed some time ago, we
+			 * If a write flush failed some time ago, we
 			 * don't know whether or not this write made it
 			 * to the disk, so we must resync the device.
 			 */

drivers/md/dm-snap-persistent.c

@@ -687,7 +687,7 @@ static void persistent_commit_exception(struct dm_exception_store *store,
 	/*
 	 * Commit exceptions to disk.
 	 */
-	if (ps->valid && area_io(ps, WRITE_BARRIER))
+	if (ps->valid && area_io(ps, WRITE_FLUSH_FUA))
 		ps->valid = 0;
 
 	/*

drivers/md/dm-snap.c

@@ -1585,7 +1585,7 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio,
 	chunk_t chunk;
 	struct dm_snap_pending_exception *pe = NULL;
 
-	if (unlikely(bio_empty_barrier(bio))) {
+	if (bio->bi_rw & REQ_FLUSH) {
 		bio->bi_bdev = s->cow->bdev;
 		return DM_MAPIO_REMAPPED;
 	}
@@ -1689,7 +1689,7 @@ static int snapshot_merge_map(struct dm_target *ti, struct bio *bio,
 	int r = DM_MAPIO_REMAPPED;
 	chunk_t chunk;
 
-	if (unlikely(bio_empty_barrier(bio))) {
+	if (bio->bi_rw & REQ_FLUSH) {
 		if (!map_context->target_request_nr)
 			bio->bi_bdev = s->origin->bdev;
 		else
@@ -2133,7 +2133,7 @@ static int origin_map(struct dm_target *ti, struct bio *bio,
 	struct dm_dev *dev = ti->private;
 	bio->bi_bdev = dev->bdev;
 
-	if (unlikely(bio_empty_barrier(bio)))
+	if (bio->bi_rw & REQ_FLUSH)
 		return DM_MAPIO_REMAPPED;
 
 	/* Only tell snapshots if this is a write */

drivers/md/dm-stripe.c

@@ -271,7 +271,7 @@ static int stripe_map(struct dm_target *ti, struct bio *bio,
 	uint32_t stripe;
 	unsigned target_request_nr;
 
-	if (unlikely(bio_empty_barrier(bio))) {
+	if (bio->bi_rw & REQ_FLUSH) {
 		target_request_nr = map_context->target_request_nr;
 		BUG_ON(target_request_nr >= sc->stripes);
 		bio->bi_bdev = sc->stripe[target_request_nr].dev->bdev;

drivers/md/dm.c

@@ -110,7 +110,6 @@ EXPORT_SYMBOL_GPL(dm_get_rq_mapinfo);
 #define DMF_FREEING 3
 #define DMF_DELETING 4
 #define DMF_NOFLUSH_SUSPENDING 5
-#define DMF_QUEUE_IO_TO_THREAD 6
 
 /*
  * Work processed by per-device workqueue.
@@ -144,24 +143,9 @@ struct mapped_device {
 	spinlock_t deferred_lock;
 
 	/*
-	 * An error from the barrier request currently being processed.
-	 */
-	int barrier_error;
-
-	/*
-	 * Protect barrier_error from concurrent endio processing
-	 * in request-based dm.
-	 */
-	spinlock_t barrier_error_lock;
-
-	/*
-	 * Processing queue (flush/barriers)
+	 * Processing queue (flush)
 	 */
 	struct workqueue_struct *wq;
-	struct work_struct barrier_work;
-
-	/* A pointer to the currently processing pre/post flush request */
-	struct request *flush_request;
 
 	/*
 	 * The current mapping.
@@ -200,8 +184,8 @@ struct mapped_device {
 	/* sysfs handle */
 	struct kobject kobj;
 
-	/* zero-length barrier that will be cloned and submitted to targets */
-	struct bio barrier_bio;
+	/* zero-length flush that will be cloned and submitted to targets */
+	struct bio flush_bio;
 };
 
 /*
@@ -512,7 +496,7 @@ static void end_io_acct(struct dm_io *io)
 
 	/*
 	 * After this is decremented the bio must not be touched if it is
-	 * a barrier.
+	 * a flush.
 	 */
 	dm_disk(md)->part0.in_flight[rw] = pending =
 		atomic_dec_return(&md->pending[rw]);
@@ -528,16 +512,12 @@ static void end_io_acct(struct dm_io *io)
  */
 static void queue_io(struct mapped_device *md, struct bio *bio)
 {
-	down_write(&md->io_lock);
+	unsigned long flags;
 
-	spin_lock_irq(&md->deferred_lock);
+	spin_lock_irqsave(&md->deferred_lock, flags);
 	bio_list_add(&md->deferred, bio);
-	spin_unlock_irq(&md->deferred_lock);
-
-	if (!test_and_set_bit(DMF_QUEUE_IO_TO_THREAD, &md->flags))
-		queue_work(md->wq, &md->work);
-
-	up_write(&md->io_lock);
+	spin_unlock_irqrestore(&md->deferred_lock, flags);
+	queue_work(md->wq, &md->work);
 }
 
 /*
@@ -625,11 +605,9 @@ static void dec_pending(struct dm_io *io, int error)
 			 * Target requested pushing back the I/O.
 			 */
 			spin_lock_irqsave(&md->deferred_lock, flags);
-			if (__noflush_suspending(md)) {
-				if (!(io->bio->bi_rw & REQ_HARDBARRIER))
-					bio_list_add_head(&md->deferred,
-							  io->bio);
-			} else
+			if (__noflush_suspending(md))
+				bio_list_add_head(&md->deferred, io->bio);
+			else
 				/* noflush suspend was interrupted. */
 				io->error = -EIO;
 			spin_unlock_irqrestore(&md->deferred_lock, flags);
@@ -637,32 +615,23 @@ static void dec_pending(struct dm_io *io, int error)
 
 		io_error = io->error;
 		bio = io->bio;
+		end_io_acct(io);
+		free_io(md, io);
+
+		if (io_error == DM_ENDIO_REQUEUE)
+			return;
 
-		if (bio->bi_rw & REQ_HARDBARRIER) {
+		if ((bio->bi_rw & REQ_FLUSH) && bio->bi_size) {
 			/*
-			 * There can be just one barrier request so we use
-			 * a per-device variable for error reporting.
-			 * Note that you can't touch the bio after end_io_acct
-			 *
-			 * We ignore -EOPNOTSUPP for empty flush reported by
-			 * underlying devices. We assume that if the device
-			 * doesn't support empty barriers, it doesn't need
-			 * cache flushing commands.
+			 * Preflush done for flush with data, reissue
+			 * without REQ_FLUSH.
 			 */
-			if (!md->barrier_error &&
-			    !(bio_empty_barrier(bio) && io_error == -EOPNOTSUPP))
-				md->barrier_error = io_error;
-			end_io_acct(io);
-			free_io(md, io);
+			bio->bi_rw &= ~REQ_FLUSH;
+			queue_io(md, bio);
 		} else {
-			end_io_acct(io);
-			free_io(md, io);
-
-			if (io_error != DM_ENDIO_REQUEUE) {
-				trace_block_bio_complete(md->queue, bio);
-
-				bio_endio(bio, io_error);
-			}
+			/* done with normal IO or empty flush */
+			trace_block_bio_complete(md->queue, bio);
+			bio_endio(bio, io_error);
 		}
 	}
 }
@@ -755,23 +724,6 @@ static void end_clone_bio(struct bio *clone, int error)
 	blk_update_request(tio->orig, 0, nr_bytes);
 }
 
-static void store_barrier_error(struct mapped_device *md, int error)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&md->barrier_error_lock, flags);
-	/*
-	 * Basically, the first error is taken, but:
-	 *   -EOPNOTSUPP supersedes any I/O error.
-	 *   Requeue request supersedes any I/O error but -EOPNOTSUPP.
-	 */
-	if (!md->barrier_error || error == -EOPNOTSUPP ||
-	    (md->barrier_error != -EOPNOTSUPP &&
-	     error == DM_ENDIO_REQUEUE))
-		md->barrier_error = error;
-	spin_unlock_irqrestore(&md->barrier_error_lock, flags);
-}
-
 /*
  * Don't touch any member of the md after calling this function because
  * the md may be freed in dm_put() at the end of this function.
@@ -809,13 +761,11 @@ static void free_rq_clone(struct request *clone)
 static void dm_end_request(struct request *clone, int error)
 {
 	int rw = rq_data_dir(clone);
-	int run_queue = 1;
-	bool is_barrier = clone->cmd_flags & REQ_HARDBARRIER;
 	struct dm_rq_target_io *tio = clone->end_io_data;
 	struct mapped_device *md = tio->md;
 	struct request *rq = tio->orig;
 
-	if (rq->cmd_type == REQ_TYPE_BLOCK_PC && !is_barrier) {
+	if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
 		rq->errors = clone->errors;
 		rq->resid_len = clone->resid_len;
 
@@ -829,15 +779,8 @@ static void dm_end_request(struct request *clone, int error)
 	}
 
 	free_rq_clone(clone);
-
-	if (unlikely(is_barrier)) {
-		if (unlikely(error))
-			store_barrier_error(md, error);
-		run_queue = 0;
-	} else
-		blk_end_request_all(rq, error);
-
-	rq_completed(md, rw, run_queue);
+	blk_end_request_all(rq, error);
+	rq_completed(md, rw, true);
 }
 
 static void dm_unprep_request(struct request *rq)
@@ -862,16 +805,6 @@ void dm_requeue_unmapped_request(struct request *clone)
 	struct request_queue *q = rq->q;
 	unsigned long flags;
 
-	if (unlikely(clone->cmd_flags & REQ_HARDBARRIER)) {
-		/*
-		 * Barrier clones share an original request.
-		 * Leave it to dm_end_request(), which handles this special
-		 * case.
-		 */
-		dm_end_request(clone, DM_ENDIO_REQUEUE);
-		return;
-	}
-
 	dm_unprep_request(rq);
 
 	spin_lock_irqsave(q->queue_lock, flags);
@@ -961,19 +894,6 @@ static void dm_complete_request(struct request *clone, int error)
 	struct dm_rq_target_io *tio = clone->end_io_data;
 	struct request *rq = tio->orig;
 
-	if (unlikely(clone->cmd_flags & REQ_HARDBARRIER)) {
-		/*
-		 * Barrier clones share an original request.  So can't use
-		 * softirq_done with the original.
-		 * Pass the clone to dm_done() directly in this special case.
-		 * It is safe (even if clone->q->queue_lock is held here)
-		 * because there is no I/O dispatching during the completion
-		 * of barrier clone.
-		 */
-		dm_done(clone, error, true);
-		return;
-	}
-
 	tio->error = error;
 	rq->completion_data = clone;
 	blk_complete_request(rq);
@@ -990,17 +910,6 @@ void dm_kill_unmapped_request(struct request *clone, int error)
 	struct dm_rq_target_io *tio = clone->end_io_data;
 	struct request *rq = tio->orig;
 
-	if (unlikely(clone->cmd_flags & REQ_HARDBARRIER)) {
-		/*
-		 * Barrier clones share an original request.
-		 * Leave it to dm_end_request(), which handles this special
-		 * case.
-		 */
-		BUG_ON(error > 0);
-		dm_end_request(clone, error);
-		return;
-	}
-
 	rq->cmd_flags |= REQ_FAILED;
 	dm_complete_request(clone, error);
 }
@@ -1119,7 +1028,7 @@ static void dm_bio_destructor(struct bio *bio)
 }
 
 /*
- * Creates a little bio that is just does part of a bvec.
+ * Creates a little bio that just does part of a bvec.
  */
 static struct bio *split_bvec(struct bio *bio, sector_t sector,
 			      unsigned short idx, unsigned int offset,
@@ -1134,7 +1043,7 @@ static struct bio *split_bvec(struct bio *bio, sector_t sector,
 
 	clone->bi_sector = sector;
 	clone->bi_bdev = bio->bi_bdev;
-	clone->bi_rw = bio->bi_rw & ~REQ_HARDBARRIER;
+	clone->bi_rw = bio->bi_rw;
 	clone->bi_vcnt = 1;
 	clone->bi_size = to_bytes(len);
 	clone->bi_io_vec->bv_offset = offset;
@@ -1161,7 +1070,6 @@ static struct bio *clone_bio(struct bio *bio, sector_t sector,
 
 	clone = bio_alloc_bioset(GFP_NOIO, bio->bi_max_vecs, bs);
 	__bio_clone(clone, bio);
-	clone->bi_rw &= ~REQ_HARDBARRIER;
 	clone->bi_destructor = dm_bio_destructor;
 	clone->bi_sector = sector;
 	clone->bi_idx = idx;
@@ -1225,16 +1133,15 @@ static void __issue_target_requests(struct clone_info *ci, struct dm_target *ti,
 		__issue_target_request(ci, ti, request_nr, len);
 }
 
-static int __clone_and_map_empty_barrier(struct clone_info *ci)
+static int __clone_and_map_empty_flush(struct clone_info *ci)
 {
 	unsigned target_nr = 0;
 	struct dm_target *ti;
 
+	BUG_ON(bio_has_data(ci->bio));
 	while ((ti = dm_table_get_target(ci->map, target_nr++)))
 		__issue_target_requests(ci, ti, ti->num_flush_requests, 0);
 
-	ci->sector_count = 0;
-
 	return 0;
 }
 
@@ -1289,9 +1196,6 @@ static int __clone_and_map(struct clone_info *ci)
 	sector_t len = 0, max;
 	struct dm_target_io *tio;
 
-	if (unlikely(bio_empty_barrier(bio)))
-		return __clone_and_map_empty_barrier(ci);
-
 	if (unlikely(bio->bi_rw & REQ_DISCARD))
 		return __clone_and_map_discard(ci);
 
@@ -1383,16 +1287,11 @@ static void __split_and_process_bio(struct mapped_device *md, struct bio *bio)
 
 	ci.map = dm_get_live_table(md);
 	if (unlikely(!ci.map)) {
-		if (!(bio->bi_rw & REQ_HARDBARRIER))
-			bio_io_error(bio);
-		else
-			if (!md->barrier_error)
-				md->barrier_error = -EIO;
+		bio_io_error(bio);
 		return;
 	}
 
 	ci.md = md;
-	ci.bio = bio;
 	ci.io = alloc_io(md);
 	ci.io->error = 0;
 	atomic_set(&ci.io->io_count, 1);
@@ -1400,14 +1299,20 @@ static void __split_and_process_bio(struct mapped_device *md, struct bio *bio)
 	ci.io->md = md;
 	spin_lock_init(&ci.io->endio_lock);
 	ci.sector = bio->bi_sector;
-	ci.sector_count = bio_sectors(bio);
-	if (unlikely(bio_empty_barrier(bio)))
-		ci.sector_count = 1;
 	ci.idx = bio->bi_idx;
 
 	start_io_acct(ci.io);
-	while (ci.sector_count && !error)
-		error = __clone_and_map(&ci);
+	if (bio->bi_rw & REQ_FLUSH) {
+		ci.bio = &ci.md->flush_bio;
+		ci.sector_count = 0;
+		error = __clone_and_map_empty_flush(&ci);
+		/* dec_pending submits any data associated with flush */
+	} else {
+		ci.bio = bio;
+		ci.sector_count = bio_sectors(bio);
+		while (ci.sector_count && !error)
+			error = __clone_and_map(&ci);
+	}
 
 	/* drop the extra reference count */
 	dec_pending(ci.io, error);
@@ -1491,22 +1396,14 @@ static int _dm_request(struct request_queue *q, struct bio *bio)
 	part_stat_add(cpu, &dm_disk(md)->part0, sectors[rw], bio_sectors(bio));
 	part_stat_unlock();
 
-	/*
-	 * If we're suspended or the thread is processing barriers
-	 * we have to queue this io for later.
-	 */
-	if (unlikely(test_bit(DMF_QUEUE_IO_TO_THREAD, &md->flags)) ||
-	    unlikely(bio->bi_rw & REQ_HARDBARRIER)) {
+	/* if we're suspended, we have to queue this io for later */
+	if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags))) {
 		up_read(&md->io_lock);
 
-		if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) &&
-		    bio_rw(bio) == READA) {
+		if (bio_rw(bio) != READA)
+			queue_io(md, bio);
+		else
 			bio_io_error(bio);
-			return 0;
-		}
-
-		queue_io(md, bio);
-
 		return 0;
 	}
 
@@ -1537,14 +1434,6 @@ static int dm_request(struct request_queue *q, struct bio *bio)
 	return _dm_request(q, bio);
 }
 
-static bool dm_rq_is_flush_request(struct request *rq)
-{
-	if (rq->cmd_flags & REQ_FLUSH)
-		return true;
-	else
-		return false;
-}
-
 void dm_dispatch_request(struct request *rq)
 {
 	int r;
@@ -1592,22 +1481,15 @@ static int setup_clone(struct request *clone, struct request *rq,
 {
 	int r;
 
-	if (dm_rq_is_flush_request(rq)) {
-		blk_rq_init(NULL, clone);
-		clone->cmd_type = REQ_TYPE_FS;
-		clone->cmd_flags |= (REQ_HARDBARRIER | WRITE);
-	} else {
-		r = blk_rq_prep_clone(clone, rq, tio->md->bs, GFP_ATOMIC,
-				      dm_rq_bio_constructor, tio);
-		if (r)
-			return r;
-
-		clone->cmd = rq->cmd;
-		clone->cmd_len = rq->cmd_len;
-		clone->sense = rq->sense;
-		clone->buffer = rq->buffer;
-	}
+	r = blk_rq_prep_clone(clone, rq, tio->md->bs, GFP_ATOMIC,
+			      dm_rq_bio_constructor, tio);
+	if (r)
+		return r;
 
+	clone->cmd = rq->cmd;
+	clone->cmd_len = rq->cmd_len;
+	clone->sense = rq->sense;
+	clone->buffer = rq->buffer;
 	clone->end_io = end_clone_request;
 	clone->end_io_data = tio;
 
@@ -1648,9 +1530,6 @@ static int dm_prep_fn(struct request_queue *q, struct request *rq)
 	struct mapped_device *md = q->queuedata;
 	struct request *clone;
 
-	if (unlikely(dm_rq_is_flush_request(rq)))
-		return BLKPREP_OK;
-
 	if (unlikely(rq->special)) {
 		DMWARN("Already has something in rq->special.");
 		return BLKPREP_KILL;
@@ -1727,6 +1606,7 @@ static void dm_request_fn(struct request_queue *q)
 	struct dm_table *map = dm_get_live_table(md);
 	struct dm_target *ti;
 	struct request *rq, *clone;
+	sector_t pos;
 
 	/*
 	 * For suspend, check blk_queue_stopped() and increment
@@ -1739,15 +1619,14 @@ static void dm_request_fn(struct request_queue *q)
 		if (!rq)
 			goto plug_and_out;
 
-		if (unlikely(dm_rq_is_flush_request(rq))) {
-			BUG_ON(md->flush_request);
-			md->flush_request = rq;
-			blk_start_request(rq);
-			queue_work(md->wq, &md->barrier_work);
-			goto out;
-		}
+		/* always use block 0 to find the target for flushes for now */
+		pos = 0;
+		if (!(rq->cmd_flags & REQ_FLUSH))
+			pos = blk_rq_pos(rq);
+
+		ti = dm_table_find_target(map, pos);
+		BUG_ON(!dm_target_is_valid(ti));
 
-		ti = dm_table_find_target(map, blk_rq_pos(rq));
 		if (ti->type->busy && ti->type->busy(ti))
 			goto plug_and_out;
 
@@ -1918,7 +1797,6 @@ static int next_free_minor(int *minor)
 static const struct block_device_operations dm_blk_dops;
 
 static void dm_wq_work(struct work_struct *work);
-static void dm_rq_barrier_work(struct work_struct *work);
 
 static void dm_init_md_queue(struct mapped_device *md)
 {
@@ -1940,6 +1818,7 @@ static void dm_init_md_queue(struct mapped_device *md)
 	blk_queue_bounce_limit(md->queue, BLK_BOUNCE_ANY);
 	md->queue->unplug_fn = dm_unplug_all;
 	blk_queue_merge_bvec(md->queue, dm_merge_bvec);
+	blk_queue_flush(md->queue, REQ_FLUSH | REQ_FUA);
 }
 
 /*
@@ -1972,7 +1851,6 @@ static struct mapped_device *alloc_dev(int minor)
 	mutex_init(&md->suspend_lock);
 	mutex_init(&md->type_lock);
 	spin_lock_init(&md->deferred_lock);
-	spin_lock_init(&md->barrier_error_lock);
 	rwlock_init(&md->map_lock);
 	atomic_set(&md->holders, 1);
 	atomic_set(&md->open_count, 0);
@@ -1995,7 +1873,6 @@ static struct mapped_device *alloc_dev(int minor)
 	atomic_set(&md->pending[1], 0);
 	init_waitqueue_head(&md->wait);
 	INIT_WORK(&md->work, dm_wq_work);
-	INIT_WORK(&md->barrier_work, dm_rq_barrier_work);
 	init_waitqueue_head(&md->eventq);
 
 	md->disk->major = _major;
@@ -2015,6 +1892,10 @@ static struct mapped_device *alloc_dev(int minor)
 	if (!md->bdev)
 		goto bad_bdev;
 
+	bio_init(&md->flush_bio);
+	md->flush_bio.bi_bdev = md->bdev;
+	md->flush_bio.bi_rw = WRITE_FLUSH;
+
 	/* Populate the mapping, nobody knows we exist yet */
 	spin_lock(&_minor_lock);
 	old_md = idr_replace(&_minor_idr, md, minor);
@@ -2245,7 +2126,6 @@ static int dm_init_request_based_queue(struct mapped_device *md)
 	blk_queue_softirq_done(md->queue, dm_softirq_done);
 	blk_queue_prep_rq(md->queue, dm_prep_fn);
 	blk_queue_lld_busy(md->queue, dm_lld_busy);
-	blk_queue_ordered(md->queue, QUEUE_ORDERED_DRAIN_FLUSH);
 
 	elv_register_queue(md->queue);
 
@@ -2406,43 +2286,6 @@ static int dm_wait_for_completion(struct mapped_device *md, int interruptible)
 	return r;
 }
 
-static void dm_flush(struct mapped_device *md)
-{
-	dm_wait_for_completion(md, TASK_UNINTERRUPTIBLE);
-
-	bio_init(&md->barrier_bio);
-	md->barrier_bio.bi_bdev = md->bdev;
-	md->barrier_bio.bi_rw = WRITE_BARRIER;
-	__split_and_process_bio(md, &md->barrier_bio);
-
-	dm_wait_for_completion(md, TASK_UNINTERRUPTIBLE);
-}
-
-static void process_barrier(struct mapped_device *md, struct bio *bio)
-{
-	md->barrier_error = 0;
-
-	dm_flush(md);
-
-	if (!bio_empty_barrier(bio)) {
-		__split_and_process_bio(md, bio);
-		/*
-		 * If the request isn't supported, don't waste time with
-		 * the second flush.
-		 */
-		if (md->barrier_error != -EOPNOTSUPP)
-			dm_flush(md);
-	}
-
-	if (md->barrier_error != DM_ENDIO_REQUEUE)
-		bio_endio(bio, md->barrier_error);
-	else {
-		spin_lock_irq(&md->deferred_lock);
-		bio_list_add_head(&md->deferred, bio);
-		spin_unlock_irq(&md->deferred_lock);
-	}
-}
-
 /*
  * Process the deferred bios
  */
@@ -2452,33 +2295,27 @@ static void dm_wq_work(struct work_struct *work)
 						work);
 	struct bio *c;
 
-	down_write(&md->io_lock);
+	down_read(&md->io_lock);
 
 	while (!test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) {
 		spin_lock_irq(&md->deferred_lock);
 		c = bio_list_pop(&md->deferred);
 		spin_unlock_irq(&md->deferred_lock);
 
-		if (!c) {
-			clear_bit(DMF_QUEUE_IO_TO_THREAD, &md->flags);
+		if (!c)
 			break;
-		}
 
-		up_write(&md->io_lock);
+		up_read(&md->io_lock);
 
 		if (dm_request_based(md))
 			generic_make_request(c);
-		else {
-			if (c->bi_rw & REQ_HARDBARRIER)
-				process_barrier(md, c);
-			else
-				__split_and_process_bio(md, c);
-		}
+		else
+			__split_and_process_bio(md, c);
 
-		down_write(&md->io_lock);
+		down_read(&md->io_lock);
 	}
 
-	up_write(&md->io_lock);
+	up_read(&md->io_lock);
 }
 
 static void dm_queue_flush(struct mapped_device *md)
@@ -2488,73 +2325,6 @@ static void dm_queue_flush(struct mapped_device *md)
 	queue_work(md->wq, &md->work);
 }
 
-static void dm_rq_set_target_request_nr(struct request *clone, unsigned request_nr)
-{
-	struct dm_rq_target_io *tio = clone->end_io_data;
-
-	tio->info.target_request_nr = request_nr;
-}
-
-/* Issue barrier requests to targets and wait for their completion. */
-static int dm_rq_barrier(struct mapped_device *md)
-{
-	int i, j;
-	struct dm_table *map = dm_get_live_table(md);
-	unsigned num_targets = dm_table_get_num_targets(map);
-	struct dm_target *ti;
-	struct request *clone;
-
-	md->barrier_error = 0;
-
-	for (i = 0; i < num_targets; i++) {
-		ti = dm_table_get_target(map, i);
-		for (j = 0; j < ti->num_flush_requests; j++) {
-			clone = clone_rq(md->flush_request, md, GFP_NOIO);
-			dm_rq_set_target_request_nr(clone, j);
-			atomic_inc(&md->pending[rq_data_dir(clone)]);
-			map_request(ti, clone, md);
-		}
-	}
-
-	dm_wait_for_completion(md, TASK_UNINTERRUPTIBLE);
-	dm_table_put(map);
-
-	return md->barrier_error;
-}
-
-static void dm_rq_barrier_work(struct work_struct *work)
-{
-	int error;
-	struct mapped_device *md = container_of(work, struct mapped_device,
-						barrier_work);
-	struct request_queue *q = md->queue;
-	struct request *rq;
-	unsigned long flags;
-
-	/*
-	 * Hold the md reference here and leave it at the last part so that
-	 * the md can't be deleted by device opener when the barrier request
-	 * completes.
-	 */
-	dm_get(md);
-
-	error = dm_rq_barrier(md);
-
-	rq = md->flush_request;
-	md->flush_request = NULL;
-
-	if (error == DM_ENDIO_REQUEUE) {
-		spin_lock_irqsave(q->queue_lock, flags);
-		blk_requeue_request(q, rq);
-		spin_unlock_irqrestore(q->queue_lock, flags);
-	} else
-		blk_end_request_all(rq, error);
-
-	blk_run_queue(q);
-
-	dm_put(md);
-}
-
 /*
  * Swap in a new table, returning the old one for the caller to destroy.
  */
@@ -2677,23 +2447,17 @@ int dm_suspend(struct mapped_device *md, unsigned suspend_flags)
 	 *
 	 * To get all processes out of __split_and_process_bio in dm_request,
 	 * we take the write lock. To prevent any process from reentering
-	 * __split_and_process_bio from dm_request, we set
-	 * DMF_QUEUE_IO_TO_THREAD.
-	 *
-	 * To quiesce the thread (dm_wq_work), we set DMF_BLOCK_IO_FOR_SUSPEND
-	 * and call flush_workqueue(md->wq). flush_workqueue will wait until
-	 * dm_wq_work exits and DMF_BLOCK_IO_FOR_SUSPEND will prevent any
-	 * further calls to __split_and_process_bio from dm_wq_work.
+	 * __split_and_process_bio from dm_request and quiesce the thread
+	 * (dm_wq_work), we set BMF_BLOCK_IO_FOR_SUSPEND and call
+	 * flush_workqueue(md->wq).
 	 */
 	down_write(&md->io_lock);
 	set_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
-	set_bit(DMF_QUEUE_IO_TO_THREAD, &md->flags);
 	up_write(&md->io_lock);
 
 	/*
-	 * Request-based dm uses md->wq for barrier (dm_rq_barrier_work) which
-	 * can be kicked until md->queue is stopped.  So stop md->queue before
-	 * flushing md->wq.
+	 * Stop md->queue before flushing md->wq in case request-based
+	 * dm defers requests to md->wq from md->queue.
 	 */
 	if (dm_request_based(md))
 		stop_queue(md->queue);

drivers/md/linear.c

@@ -294,8 +294,8 @@ static int linear_make_request (mddev_t *mddev, struct bio *bio)
 	dev_info_t *tmp_dev;
 	sector_t start_sector;
 
-	if (unlikely(bio->bi_rw & REQ_HARDBARRIER)) {
-		md_barrier_request(mddev, bio);
+	if (unlikely(bio->bi_rw & REQ_FLUSH)) {
+		md_flush_request(mddev, bio);
 		return 0;
 	}
 

drivers/md/md.c

@@ -227,12 +227,12 @@ static int md_make_request(struct request_queue *q, struct bio *bio)
 		return 0;
 	}
 	rcu_read_lock();
-	if (mddev->suspended || mddev->barrier) {
+	if (mddev->suspended) {
 		DEFINE_WAIT(__wait);
 		for (;;) {
 			prepare_to_wait(&mddev->sb_wait, &__wait,
 					TASK_UNINTERRUPTIBLE);
-			if (!mddev->suspended && !mddev->barrier)
+			if (!mddev->suspended)
 				break;
 			rcu_read_unlock();
 			schedule();
@@ -283,40 +283,29 @@ EXPORT_SYMBOL_GPL(mddev_resume);
 
 int mddev_congested(mddev_t *mddev, int bits)
 {
-	if (mddev->barrier)
-		return 1;
 	return mddev->suspended;
 }
 EXPORT_SYMBOL(mddev_congested);
 
 /*
- * Generic barrier handling for md
+ * Generic flush handling for md
  */
 
-#define POST_REQUEST_BARRIER ((void*)1)
-
-static void md_end_barrier(struct bio *bio, int err)
+static void md_end_flush(struct bio *bio, int err)
 {
 	mdk_rdev_t *rdev = bio->bi_private;
 	mddev_t *mddev = rdev->mddev;
-	if (err == -EOPNOTSUPP && mddev->barrier != POST_REQUEST_BARRIER)
-		set_bit(BIO_EOPNOTSUPP, &mddev->barrier->bi_flags);
 
 	rdev_dec_pending(rdev, mddev);
 
 	if (atomic_dec_and_test(&mddev->flush_pending)) {
-		if (mddev->barrier == POST_REQUEST_BARRIER) {
-			/* This was a post-request barrier */
-			mddev->barrier = NULL;
-			wake_up(&mddev->sb_wait);
-		} else
-			/* The pre-request barrier has finished */
-			schedule_work(&mddev->barrier_work);
+		/* The pre-request flush has finished */
+		schedule_work(&mddev->flush_work);
 	}
 	bio_put(bio);
 }
 
-static void submit_barriers(mddev_t *mddev)
+static void submit_flushes(mddev_t *mddev)
 {
 	mdk_rdev_t *rdev;
 
@@ -333,60 +322,56 @@ static void submit_barriers(mddev_t *mddev)
 			atomic_inc(&rdev->nr_pending);
 			rcu_read_unlock();
 			bi = bio_alloc(GFP_KERNEL, 0);
-			bi->bi_end_io = md_end_barrier;
+			bi->bi_end_io = md_end_flush;
 			bi->bi_private = rdev;
 			bi->bi_bdev = rdev->bdev;
 			atomic_inc(&mddev->flush_pending);
-			submit_bio(WRITE_BARRIER, bi);
+			submit_bio(WRITE_FLUSH, bi);
 			rcu_read_lock();
 			rdev_dec_pending(rdev, mddev);
 		}
 	rcu_read_unlock();
 }
 
-static void md_submit_barrier(struct work_struct *ws)
+static void md_submit_flush_data(struct work_struct *ws)
 {
-	mddev_t *mddev = container_of(ws, mddev_t, barrier_work);
-	struct bio *bio = mddev->barrier;
+	mddev_t *mddev = container_of(ws, mddev_t, flush_work);
+	struct bio *bio = mddev->flush_bio;
 
 	atomic_set(&mddev->flush_pending, 1);
 
-	if (test_bit(BIO_EOPNOTSUPP, &bio->bi_flags))
-		bio_endio(bio, -EOPNOTSUPP);
-	else if (bio->bi_size == 0)
+	if (bio->bi_size == 0)
 		/* an empty barrier - all done */
 		bio_endio(bio, 0);
 	else {
-		bio->bi_rw &= ~REQ_HARDBARRIER;
+		bio->bi_rw &= ~REQ_FLUSH;
 		if (mddev->pers->make_request(mddev, bio))
 			generic_make_request(bio);
-		mddev->barrier = POST_REQUEST_BARRIER;
-		submit_barriers(mddev);
 	}
 	if (atomic_dec_and_test(&mddev->flush_pending)) {
-		mddev->barrier = NULL;
+		mddev->flush_bio = NULL;
 		wake_up(&mddev->sb_wait);
 	}
 }
 
-void md_barrier_request(mddev_t *mddev, struct bio *bio)
+void md_flush_request(mddev_t *mddev, struct bio *bio)
 {
 	spin_lock_irq(&mddev->write_lock);
 	wait_event_lock_irq(mddev->sb_wait,
-			    !mddev->barrier,
+			    !mddev->flush_bio,
 			    mddev->write_lock, /*nothing*/);
-	mddev->barrier = bio;
+	mddev->flush_bio = bio;
 	spin_unlock_irq(&mddev->write_lock);
 
 	atomic_set(&mddev->flush_pending, 1);
-	INIT_WORK(&mddev->barrier_work, md_submit_barrier);
+	INIT_WORK(&mddev->flush_work, md_submit_flush_data);
 
-	submit_barriers(mddev);
+	submit_flushes(mddev);
 
 	if (atomic_dec_and_test(&mddev->flush_pending))
-		schedule_work(&mddev->barrier_work);
+		schedule_work(&mddev->flush_work);
 }
-EXPORT_SYMBOL(md_barrier_request);
+EXPORT_SYMBOL(md_flush_request);
 
 /* Support for plugging.
  * This mirrors the plugging support in request_queue, but does not
@@ -697,31 +682,6 @@ static void super_written(struct bio *bio, int error)
 	bio_put(bio);
 }
 
-static void super_written_barrier(struct bio *bio, int error)
-{
-	struct bio *bio2 = bio->bi_private;
-	mdk_rdev_t *rdev = bio2->bi_private;
-	mddev_t *mddev = rdev->mddev;
-
-	if (!test_bit(BIO_UPTODATE, &bio->bi_flags) &&
-	    error == -EOPNOTSUPP) {
-		unsigned long flags;
-		/* barriers don't appear to be supported :-( */
-		set_bit(BarriersNotsupp, &rdev->flags);
-		mddev->barriers_work = 0;
-		spin_lock_irqsave(&mddev->write_lock, flags);
-		bio2->bi_next = mddev->biolist;
-		mddev->biolist = bio2;
-		spin_unlock_irqrestore(&mddev->write_lock, flags);
-		wake_up(&mddev->sb_wait);
-		bio_put(bio);
-	} else {
-		bio_put(bio2);
-		bio->bi_private = rdev;
-		super_written(bio, error);
-	}
-}
-
 void md_super_write(mddev_t *mddev, mdk_rdev_t *rdev,
 		   sector_t sector, int size, struct page *page)
 {
@@ -730,51 +690,28 @@ void md_super_write(mddev_t *mddev, mdk_rdev_t *rdev,
 	 * and decrement it on completion, waking up sb_wait
 	 * if zero is reached.
 	 * If an error occurred, call md_error
-	 *
-	 * As we might need to resubmit the request if REQ_HARDBARRIER
-	 * causes ENOTSUPP, we allocate a spare bio...
 	 */
 	struct bio *bio = bio_alloc(GFP_NOIO, 1);
-	int rw = REQ_WRITE | REQ_SYNC | REQ_UNPLUG;
 
 	bio->bi_bdev = rdev->bdev;
 	bio->bi_sector = sector;
 	bio_add_page(bio, page, size, 0);
 	bio->bi_private = rdev;
 	bio->bi_end_io = super_written;
-	bio->bi_rw = rw;
 
 	atomic_inc(&mddev->pending_writes);
-	if (!test_bit(BarriersNotsupp, &rdev->flags)) {
-		struct bio *rbio;
-		rw |= REQ_HARDBARRIER;
-		rbio = bio_clone(bio, GFP_NOIO);
-		rbio->bi_private = bio;
-		rbio->bi_end_io = super_written_barrier;
-		submit_bio(rw, rbio);
-	} else
-		submit_bio(rw, bio);
+	submit_bio(REQ_WRITE | REQ_SYNC | REQ_UNPLUG | REQ_FLUSH | REQ_FUA,
+		   bio);
 }
 
 void md_super_wait(mddev_t *mddev)
 {
-	/* wait for all superblock writes that were scheduled to complete.
-	 * if any had to be retried (due to BARRIER problems), retry them
-	 */
+	/* wait for all superblock writes that were scheduled to complete */
 	DEFINE_WAIT(wq);
 	for(;;) {
 		prepare_to_wait(&mddev->sb_wait, &wq, TASK_UNINTERRUPTIBLE);
 		if (atomic_read(&mddev->pending_writes)==0)
 			break;
-		while (mddev->biolist) {
-			struct bio *bio;
-			spin_lock_irq(&mddev->write_lock);
-			bio = mddev->biolist;
-			mddev->biolist = bio->bi_next ;
-			bio->bi_next = NULL;
-			spin_unlock_irq(&mddev->write_lock);
-			submit_bio(bio->bi_rw, bio);
-		}
 		schedule();
 	}
 	finish_wait(&mddev->sb_wait, &wq);
@@ -1071,7 +1008,6 @@ static int super_90_validate(mddev_t *mddev, mdk_rdev_t *rdev)
 	clear_bit(Faulty, &rdev->flags);
 	clear_bit(In_sync, &rdev->flags);
 	clear_bit(WriteMostly, &rdev->flags);
-	clear_bit(BarriersNotsupp, &rdev->flags);
 
 	if (mddev->raid_disks == 0) {
 		mddev->major_version = 0;
@@ -1486,7 +1422,6 @@ static int super_1_validate(mddev_t *mddev, mdk_rdev_t *rdev)
 	clear_bit(Faulty, &rdev->flags);
 	clear_bit(In_sync, &rdev->flags);
 	clear_bit(WriteMostly, &rdev->flags);
-	clear_bit(BarriersNotsupp, &rdev->flags);
 
 	if (mddev->raid_disks == 0) {
 		mddev->major_version = 1;
@@ -4505,7 +4440,6 @@ int md_run(mddev_t *mddev)
 	/* may be over-ridden by personality */
 	mddev->resync_max_sectors = mddev->dev_sectors;
 
-	mddev->barriers_work = 1;
 	mddev->ok_start_degraded = start_dirty_degraded;
 
 	if (start_readonly && mddev->ro == 0)
@@ -4684,7 +4618,6 @@ static void md_clean(mddev_t *mddev)
 	mddev->recovery = 0;
 	mddev->in_sync = 0;
 	mddev->degraded = 0;
-	mddev->barriers_work = 0;
 	mddev->safemode = 0;
 	mddev->bitmap_info.offset = 0;
 	mddev->bitmap_info.default_offset = 0;

drivers/md/md.h

@@ -87,7 +87,6 @@ struct mdk_rdev_s
 #define	Faulty		1		/* device is known to have a fault */
 #define	In_sync		2		/* device is in_sync with rest of array */
 #define	WriteMostly	4		/* Avoid reading if at all possible */
-#define	BarriersNotsupp	5		/* REQ_HARDBARRIER is not supported */
 #define	AllReserved	6		/* If whole device is reserved for
 					 * one array */
 #define	AutoDetected	7		/* added by auto-detect */
@@ -273,13 +272,6 @@ struct mddev_s
 	int				degraded;	/* whether md should consider
 							 * adding a spare
 							 */
-	int				barriers_work;	/* initialised to true, cleared as soon
-							 * as a barrier request to slave
-							 * fails.  Only supported
-							 */
-	struct bio			*biolist; 	/* bios that need to be retried
-							 * because REQ_HARDBARRIER is not supported
-							 */
 
 	atomic_t			recovery_active; /* blocks scheduled, but not written */
 	wait_queue_head_t		recovery_wait;
@@ -339,16 +331,13 @@ struct mddev_s
 	struct attribute_group		*to_remove;
 	struct plug_handle		*plug; /* if used by personality */
 
-	/* Generic barrier handling.
-	 * If there is a pending barrier request, all other
-	 * writes are blocked while the devices are flushed.
-	 * The last to finish a flush schedules a worker to
-	 * submit the barrier request (without the barrier flag),
-	 * then submit more flush requests.
+	/* Generic flush handling.
+	 * The last to finish preflush schedules a worker to submit
+	 * the rest of the request (without the REQ_FLUSH flag).
 	 */
-	struct bio *barrier;
+	struct bio *flush_bio;
 	atomic_t flush_pending;
-	struct work_struct barrier_work;
+	struct work_struct flush_work;
 	struct work_struct event_work;	/* used by dm to report failure event */
 };
 
@@ -502,7 +491,7 @@ extern void md_done_sync(mddev_t *mddev, int blocks, int ok);
 extern void md_error(mddev_t *mddev, mdk_rdev_t *rdev);
 
 extern int mddev_congested(mddev_t *mddev, int bits);
-extern void md_barrier_request(mddev_t *mddev, struct bio *bio);
+extern void md_flush_request(mddev_t *mddev, struct bio *bio);
 extern void md_super_write(mddev_t *mddev, mdk_rdev_t *rdev,
 			   sector_t sector, int size, struct page *page);
 extern void md_super_wait(mddev_t *mddev);

drivers/md/multipath.c

@@ -142,8 +142,8 @@ static int multipath_make_request(mddev_t *mddev, struct bio * bio)
 	struct multipath_bh * mp_bh;
 	struct multipath_info *multipath;
 
-	if (unlikely(bio->bi_rw & REQ_HARDBARRIER)) {
-		md_barrier_request(mddev, bio);
+	if (unlikely(bio->bi_rw & REQ_FLUSH)) {
+		md_flush_request(mddev, bio);
 		return 0;
 	}
 

drivers/md/raid0.c

@@ -483,8 +483,8 @@ static int raid0_make_request(mddev_t *mddev, struct bio *bio)
 	struct strip_zone *zone;
 	mdk_rdev_t *tmp_dev;
 
-	if (unlikely(bio->bi_rw & REQ_HARDBARRIER)) {
-		md_barrier_request(mddev, bio);
+	if (unlikely(bio->bi_rw & REQ_FLUSH)) {
+		md_flush_request(mddev, bio);
 		return 0;
 	}
 

drivers/md/raid1.c

@@ -319,83 +319,74 @@ static void raid1_end_write_request(struct bio *bio, int error)
 		if (r1_bio->bios[mirror] == bio)
 			break;
 
-	if (error == -EOPNOTSUPP && test_bit(R1BIO_Barrier, &r1_bio->state)) {
-		set_bit(BarriersNotsupp, &conf->mirrors[mirror].rdev->flags);
-		set_bit(R1BIO_BarrierRetry, &r1_bio->state);
-		r1_bio->mddev->barriers_work = 0;
-		/* Don't rdev_dec_pending in this branch - keep it for the retry */
-	} else {
+	/*
+	 * 'one mirror IO has finished' event handler:
+	 */
+	r1_bio->bios[mirror] = NULL;
+	to_put = bio;
+	if (!uptodate) {
+		md_error(r1_bio->mddev, conf->mirrors[mirror].rdev);
+		/* an I/O failed, we can't clear the bitmap */
+		set_bit(R1BIO_Degraded, &r1_bio->state);
+	} else
 		/*
-		 * this branch is our 'one mirror IO has finished' event handler:
+		 * Set R1BIO_Uptodate in our master bio, so that we
+		 * will return a good error code for to the higher
+		 * levels even if IO on some other mirrored buffer
+		 * fails.
+		 *
+		 * The 'master' represents the composite IO operation
+		 * to user-side. So if something waits for IO, then it
+		 * will wait for the 'master' bio.
 		 */
-		r1_bio->bios[mirror] = NULL;
-		to_put = bio;
-		if (!uptodate) {
-			md_error(r1_bio->mddev, conf->mirrors[mirror].rdev);
-			/* an I/O failed, we can't clear the bitmap */
-			set_bit(R1BIO_Degraded, &r1_bio->state);
-		} else
-			/*
-			 * Set R1BIO_Uptodate in our master bio, so that
-			 * we will return a good error code for to the higher
-			 * levels even if IO on some other mirrored buffer fails.
-			 *
-			 * The 'master' represents the composite IO operation to
-			 * user-side. So if something waits for IO, then it will
-			 * wait for the 'master' bio.
-			 */
-			set_bit(R1BIO_Uptodate, &r1_bio->state);
-
-		update_head_pos(mirror, r1_bio);
-
-		if (behind) {
-			if (test_bit(WriteMostly, &conf->mirrors[mirror].rdev->flags))
-				atomic_dec(&r1_bio->behind_remaining);
-
-			/* In behind mode, we ACK the master bio once the I/O has safely
-			 * reached all non-writemostly disks. Setting the Returned bit
-			 * ensures that this gets done only once -- we don't ever want to
-			 * return -EIO here, instead we'll wait */
-
-			if (atomic_read(&r1_bio->behind_remaining) >= (atomic_read(&r1_bio->remaining)-1) &&
-			    test_bit(R1BIO_Uptodate, &r1_bio->state)) {
-				/* Maybe we can return now */
-				if (!test_and_set_bit(R1BIO_Returned, &r1_bio->state)) {
-					struct bio *mbio = r1_bio->master_bio;
-					PRINTK(KERN_DEBUG "raid1: behind end write sectors %llu-%llu\n",
-					       (unsigned long long) mbio->bi_sector,
-					       (unsigned long long) mbio->bi_sector +
-					       (mbio->bi_size >> 9) - 1);
-					bio_endio(mbio, 0);
-				}
+		set_bit(R1BIO_Uptodate, &r1_bio->state);
+
+	update_head_pos(mirror, r1_bio);
+
+	if (behind) {
+		if (test_bit(WriteMostly, &conf->mirrors[mirror].rdev->flags))
+			atomic_dec(&r1_bio->behind_remaining);
+
+		/*
+		 * In behind mode, we ACK the master bio once the I/O
+		 * has safely reached all non-writemostly
+		 * disks. Setting the Returned bit ensures that this
+		 * gets done only once -- we don't ever want to return
+		 * -EIO here, instead we'll wait
+		 */
+		if (atomic_read(&r1_bio->behind_remaining) >= (atomic_read(&r1_bio->remaining)-1) &&
+		    test_bit(R1BIO_Uptodate, &r1_bio->state)) {
+			/* Maybe we can return now */
+			if (!test_and_set_bit(R1BIO_Returned, &r1_bio->state)) {
+				struct bio *mbio = r1_bio->master_bio;
+				PRINTK(KERN_DEBUG "raid1: behind end write sectors %llu-%llu\n",
+				       (unsigned long long) mbio->bi_sector,
+				       (unsigned long long) mbio->bi_sector +
+				       (mbio->bi_size >> 9) - 1);
+				bio_endio(mbio, 0);
 			}
 		}
-		rdev_dec_pending(conf->mirrors[mirror].rdev, conf->mddev);
 	}
+	rdev_dec_pending(conf->mirrors[mirror].rdev, conf->mddev);
+
 	/*
-	 *
 	 * Let's see if all mirrored write operations have finished
 	 * already.
 	 */
 	if (atomic_dec_and_test(&r1_bio->remaining)) {
-		if (test_bit(R1BIO_BarrierRetry, &r1_bio->state))
-			reschedule_retry(r1_bio);
-		else {
-			/* it really is the end of this request */
-			if (test_bit(R1BIO_BehindIO, &r1_bio->state)) {
-				/* free extra copy of the data pages */
-				int i = bio->bi_vcnt;
-				while (i--)
-					safe_put_page(bio->bi_io_vec[i].bv_page);
-			}
-			/* clear the bitmap if all writes complete successfully */
-			bitmap_endwrite(r1_bio->mddev->bitmap, r1_bio->sector,
-					r1_bio->sectors,
-					!test_bit(R1BIO_Degraded, &r1_bio->state),
-					behind);
-			md_write_end(r1_bio->mddev);
-			raid_end_bio_io(r1_bio);
+		if (test_bit(R1BIO_BehindIO, &r1_bio->state)) {
+			/* free extra copy of the data pages */
+			int i = bio->bi_vcnt;
+			while (i--)
+				safe_put_page(bio->bi_io_vec[i].bv_page);
 		}
+		/* clear the bitmap if all writes complete successfully */
+		bitmap_endwrite(r1_bio->mddev->bitmap, r1_bio->sector,
+				r1_bio->sectors,
+				!test_bit(R1BIO_Degraded, &r1_bio->state),
+				behind);
+		md_write_end(r1_bio->mddev);
+		raid_end_bio_io(r1_bio);
 	}
 
 	if (to_put)
@@ -788,16 +779,13 @@ static int make_request(mddev_t *mddev, struct bio * bio)
 	struct page **behind_pages = NULL;
 	const int rw = bio_data_dir(bio);
 	const unsigned long do_sync = (bio->bi_rw & REQ_SYNC);
-	unsigned long do_barriers;
+	const unsigned long do_flush_fua = (bio->bi_rw & (REQ_FLUSH | REQ_FUA));
 	mdk_rdev_t *blocked_rdev;
 
 	/*
 	 * Register the new request and wait if the reconstruction
 	 * thread has put up a bar for new requests.
 	 * Continue immediately if no resync is active currently.
-	 * We test barriers_work *after* md_write_start as md_write_start
-	 * may cause the first superblock write, and that will check out
-	 * if barriers work.
 	 */
 
 	md_write_start(mddev, bio); /* wait on superblock update early */
@@ -821,13 +809,6 @@ static int make_request(mddev_t *mddev, struct bio * bio)
 		}
 		finish_wait(&conf->wait_barrier, &w);
 	}
-	if (unlikely(!mddev->barriers_work &&
-		     (bio->bi_rw & REQ_HARDBARRIER))) {
-		if (rw == WRITE)
-			md_write_end(mddev);
-		bio_endio(bio, -EOPNOTSUPP);
-		return 0;
-	}
 
 	wait_barrier(conf);
 
@@ -959,10 +940,6 @@ static int make_request(mddev_t *mddev, struct bio * bio)
 	atomic_set(&r1_bio->remaining, 0);
 	atomic_set(&r1_bio->behind_remaining, 0);
 
-	do_barriers = bio->bi_rw & REQ_HARDBARRIER;
-	if (do_barriers)
-		set_bit(R1BIO_Barrier, &r1_bio->state);
-
 	bio_list_init(&bl);
 	for (i = 0; i < disks; i++) {
 		struct bio *mbio;
@@ -975,7 +952,7 @@ static int make_request(mddev_t *mddev, struct bio * bio)
 		mbio->bi_sector	= r1_bio->sector + conf->mirrors[i].rdev->data_offset;
 		mbio->bi_bdev = conf->mirrors[i].rdev->bdev;
 		mbio->bi_end_io	= raid1_end_write_request;
-		mbio->bi_rw = WRITE | do_barriers | do_sync;
+		mbio->bi_rw = WRITE | do_flush_fua | do_sync;
 		mbio->bi_private = r1_bio;
 
 		if (behind_pages) {
@@ -1634,41 +1611,6 @@ static void raid1d(mddev_t *mddev)
 		if (test_bit(R1BIO_IsSync, &r1_bio->state)) {
 			sync_request_write(mddev, r1_bio);
 			unplug = 1;
-		} else if (test_bit(R1BIO_BarrierRetry, &r1_bio->state)) {
-			/* some requests in the r1bio were REQ_HARDBARRIER
-			 * requests which failed with -EOPNOTSUPP.  Hohumm..
-			 * Better resubmit without the barrier.
-			 * We know which devices to resubmit for, because
-			 * all others have had their bios[] entry cleared.
-			 * We already have a nr_pending reference on these rdevs.
-			 */
-			int i;
-			const unsigned long do_sync = (r1_bio->master_bio->bi_rw & REQ_SYNC);
-			clear_bit(R1BIO_BarrierRetry, &r1_bio->state);
-			clear_bit(R1BIO_Barrier, &r1_bio->state);
-			for (i=0; i < conf->raid_disks; i++)
-				if (r1_bio->bios[i])
-					atomic_inc(&r1_bio->remaining);
-			for (i=0; i < conf->raid_disks; i++)
-				if (r1_bio->bios[i]) {
-					struct bio_vec *bvec;
-					int j;
-
-					bio = bio_clone(r1_bio->master_bio, GFP_NOIO);
-					/* copy pages from the failed bio, as
-					 * this might be a write-behind device */
-					__bio_for_each_segment(bvec, bio, j, 0)
-						bvec->bv_page = bio_iovec_idx(r1_bio->bios[i], j)->bv_page;
-					bio_put(r1_bio->bios[i]);
-					bio->bi_sector = r1_bio->sector +
-						conf->mirrors[i].rdev->data_offset;
-					bio->bi_bdev = conf->mirrors[i].rdev->bdev;
-					bio->bi_end_io = raid1_end_write_request;
-					bio->bi_rw = WRITE | do_sync;
-					bio->bi_private = r1_bio;
-					r1_bio->bios[i] = bio;
-					generic_make_request(bio);
-				}
 		} else {
 			int disk;
 

drivers/md/raid1.h

@@ -117,8 +117,6 @@ struct r1bio_s {
 #define	R1BIO_IsSync	1
 #define	R1BIO_Degraded	2
 #define	R1BIO_BehindIO	3
-#define	R1BIO_Barrier	4
-#define R1BIO_BarrierRetry 5
 /* For write-behind requests, we call bi_end_io when
  * the last non-write-behind device completes, providing
  * any write was successful.  Otherwise we call when

drivers/md/raid10.c

@@ -800,12 +800,13 @@ static int make_request(mddev_t *mddev, struct bio * bio)
 	int chunk_sects = conf->chunk_mask + 1;
 	const int rw = bio_data_dir(bio);
 	const unsigned long do_sync = (bio->bi_rw & REQ_SYNC);
+	const unsigned long do_fua = (bio->bi_rw & REQ_FUA);
 	struct bio_list bl;
 	unsigned long flags;
 	mdk_rdev_t *blocked_rdev;
 
-	if (unlikely(bio->bi_rw & REQ_HARDBARRIER)) {
-		md_barrier_request(mddev, bio);
+	if (unlikely(bio->bi_rw & REQ_FLUSH)) {
+		md_flush_request(mddev, bio);
 		return 0;
 	}
 
@@ -965,7 +966,7 @@ static int make_request(mddev_t *mddev, struct bio * bio)
 			conf->mirrors[d].rdev->data_offset;
 		mbio->bi_bdev = conf->mirrors[d].rdev->bdev;
 		mbio->bi_end_io	= raid10_end_write_request;
-		mbio->bi_rw = WRITE | do_sync;
+		mbio->bi_rw = WRITE | do_sync | do_fua;
 		mbio->bi_private = r10_bio;
 
 		atomic_inc(&r10_bio->remaining);

drivers/md/raid5.c

@@ -506,9 +506,12 @@ static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
 		int rw;
 		struct bio *bi;
 		mdk_rdev_t *rdev;
-		if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags))
-			rw = WRITE;
-		else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
+		if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags)) {
+			if (test_and_clear_bit(R5_WantFUA, &sh->dev[i].flags))
+				rw = WRITE_FUA;
+			else
+				rw = WRITE;
+		} else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
 			rw = READ;
 		else
 			continue;
@@ -1031,6 +1034,8 @@ ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
 
 			while (wbi && wbi->bi_sector <
 				dev->sector + STRIPE_SECTORS) {
+				if (wbi->bi_rw & REQ_FUA)
+					set_bit(R5_WantFUA, &dev->flags);
 				tx = async_copy_data(1, wbi, dev->page,
 					dev->sector, tx);
 				wbi = r5_next_bio(wbi, dev->sector);
@@ -1048,15 +1053,22 @@ static void ops_complete_reconstruct(void *stripe_head_ref)
 	int pd_idx = sh->pd_idx;
 	int qd_idx = sh->qd_idx;
 	int i;
+	bool fua = false;
 
 	pr_debug("%s: stripe %llu\n", __func__,
 		(unsigned long long)sh->sector);
 
+	for (i = disks; i--; )
+		fua |= test_bit(R5_WantFUA, &sh->dev[i].flags);
+
 	for (i = disks; i--; ) {
 		struct r5dev *dev = &sh->dev[i];
 
-		if (dev->written || i == pd_idx || i == qd_idx)
+		if (dev->written || i == pd_idx || i == qd_idx) {
 			set_bit(R5_UPTODATE, &dev->flags);
+			if (fua)
+				set_bit(R5_WantFUA, &dev->flags);
+		}
 	}
 
 	if (sh->reconstruct_state == reconstruct_state_drain_run)
@@ -3281,7 +3293,7 @@ static void handle_stripe5(struct stripe_head *sh)
 
 	if (dec_preread_active) {
 		/* We delay this until after ops_run_io so that if make_request
-		 * is waiting on a barrier, it won't continue until the writes
+		 * is waiting on a flush, it won't continue until the writes
 		 * have actually been submitted.
 		 */
 		atomic_dec(&conf->preread_active_stripes);
@@ -3583,7 +3595,7 @@ static void handle_stripe6(struct stripe_head *sh)
 
 	if (dec_preread_active) {
 		/* We delay this until after ops_run_io so that if make_request
-		 * is waiting on a barrier, it won't continue until the writes
+		 * is waiting on a flush, it won't continue until the writes
 		 * have actually been submitted.
 		 */
 		atomic_dec(&conf->preread_active_stripes);
@@ -3978,14 +3990,8 @@ static int make_request(mddev_t *mddev, struct bio * bi)
 	const int rw = bio_data_dir(bi);
 	int remaining;
 
-	if (unlikely(bi->bi_rw & REQ_HARDBARRIER)) {
-		/* Drain all pending writes.  We only really need
-		 * to ensure they have been submitted, but this is
-		 * easier.
-		 */
-		mddev->pers->quiesce(mddev, 1);
-		mddev->pers->quiesce(mddev, 0);
-		md_barrier_request(mddev, bi);
+	if (unlikely(bi->bi_rw & REQ_FLUSH)) {
+		md_flush_request(mddev, bi);
 		return 0;
 	}
 
@@ -4103,7 +4109,7 @@ static int make_request(mddev_t *mddev, struct bio * bi)
 			finish_wait(&conf->wait_for_overlap, &w);
 			set_bit(STRIPE_HANDLE, &sh->state);
 			clear_bit(STRIPE_DELAYED, &sh->state);
-			if (mddev->barrier && 
+			if ((bi->bi_rw & REQ_SYNC) &&
 			    !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
 				atomic_inc(&conf->preread_active_stripes);
 			release_stripe(sh);
@@ -4126,13 +4132,6 @@ static int make_request(mddev_t *mddev, struct bio * bi)
 		bio_endio(bi, 0);
 	}
 
-	if (mddev->barrier) {
-		/* We need to wait for the stripes to all be handled.
-		 * So: wait for preread_active_stripes to drop to 0.
-		 */
-		wait_event(mddev->thread->wqueue,
-			   atomic_read(&conf->preread_active_stripes) == 0);
-	}
 	return 0;
 }
 

drivers/md/raid5.h

@@ -275,6 +275,7 @@ struct r6_state {
 				    * filling
 				    */
 #define R5_Wantdrain	13 /* dev->towrite needs to be drained */
+#define R5_WantFUA	14	/* Write should be FUA */
 /*
  * Write method
  */

drivers/mmc/card/queue.c

@@ -128,7 +128,6 @@ int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card, spinlock_t *lock
 	mq->req = NULL;
 
 	blk_queue_prep_rq(mq->queue, mmc_prep_request);
-	blk_queue_ordered(mq->queue, QUEUE_ORDERED_DRAIN);
 	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, mq->queue);
 	if (mmc_can_erase(card)) {
 		queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mq->queue);

drivers/s390/block/dasd.c

@@ -2196,7 +2196,6 @@ static void dasd_setup_queue(struct dasd_block *block)
 	 */
 	blk_queue_max_segment_size(block->request_queue, PAGE_SIZE);
 	blk_queue_segment_boundary(block->request_queue, PAGE_SIZE - 1);
-	blk_queue_ordered(block->request_queue, QUEUE_ORDERED_DRAIN);
 }
 
 /*

drivers/scsi/aic7xxx_old.c

@@ -2850,12 +2850,6 @@ aic7xxx_done(struct aic7xxx_host *p, struct aic7xxx_scb *scb)
       aic_dev->r_total++;
       ptr = aic_dev->r_bins;
     }
-    if(cmd->device->simple_tags && cmd->request->cmd_flags & REQ_HARDBARRIER)
-    {
-      aic_dev->barrier_total++;
-      if(scb->tag_action == MSG_ORDERED_Q_TAG)
-        aic_dev->ordered_total++;
-    }
     x = scb->sg_length;
     x >>= 10;
     for(i=0; i<6; i++)
@@ -10125,7 +10119,6 @@ static void aic7xxx_buildscb(struct aic7xxx_host *p, struct scsi_cmnd *cmd,
   struct aic_dev_data *aic_dev = cmd->device->hostdata;
   struct scsi_device *sdptr = cmd->device;
   unsigned char tindex = TARGET_INDEX(cmd);
-  struct request *req = cmd->request;
   int use_sg;
 
   mask = (0x01 << tindex);
@@ -10144,19 +10137,8 @@ static void aic7xxx_buildscb(struct aic7xxx_host *p, struct scsi_cmnd *cmd,
     /* We always force TEST_UNIT_READY to untagged */
     if (cmd->cmnd[0] != TEST_UNIT_READY && sdptr->simple_tags)
     {
-      if (req->cmd_flags & REQ_HARDBARRIER)
-      {
-	if(sdptr->ordered_tags)
-	{
-          hscb->control |= MSG_ORDERED_Q_TAG;
-          scb->tag_action = MSG_ORDERED_Q_TAG;
-	}
-      }
-      else
-      {
-        hscb->control |= MSG_SIMPLE_Q_TAG;
-        scb->tag_action = MSG_SIMPLE_Q_TAG;
-      }
+      hscb->control |= MSG_SIMPLE_Q_TAG;
+      scb->tag_action = MSG_SIMPLE_Q_TAG;
     }
   }
   if ( !(aic_dev->dtr_pending) &&

drivers/scsi/libsas/sas_scsi_host.c

@@ -130,17 +130,6 @@ static void sas_scsi_task_done(struct sas_task *task)
 	sc->scsi_done(sc);
 }
 
-static enum task_attribute sas_scsi_get_task_attr(struct scsi_cmnd *cmd)
-{
-	enum task_attribute ta = TASK_ATTR_SIMPLE;
-	if (cmd->request && blk_rq_tagged(cmd->request)) {
-		if (cmd->device->ordered_tags &&
-		    (cmd->request->cmd_flags & REQ_HARDBARRIER))
-			ta = TASK_ATTR_ORDERED;
-	}
-	return ta;
-}
-
 static struct sas_task *sas_create_task(struct scsi_cmnd *cmd,
 					       struct domain_device *dev,
 					       gfp_t gfp_flags)
@@ -160,7 +149,7 @@ static struct sas_task *sas_create_task(struct scsi_cmnd *cmd,
 	task->ssp_task.retry_count = 1;
 	int_to_scsilun(cmd->device->lun, &lun);
 	memcpy(task->ssp_task.LUN, &lun.scsi_lun, 8);
-	task->ssp_task.task_attr = sas_scsi_get_task_attr(cmd);
+	task->ssp_task.task_attr = TASK_ATTR_SIMPLE;
 	memcpy(task->ssp_task.cdb, cmd->cmnd, 16);
 
 	task->scatter = scsi_sglist(cmd);

drivers/scsi/sd.c

@@ -2109,7 +2109,7 @@ static int sd_revalidate_disk(struct gendisk *disk)
 	struct scsi_disk *sdkp = scsi_disk(disk);
 	struct scsi_device *sdp = sdkp->device;
 	unsigned char *buffer;
-	unsigned ordered;
+	unsigned flush = 0;
 
 	SCSI_LOG_HLQUEUE(3, sd_printk(KERN_INFO, sdkp,
 				      "sd_revalidate_disk\n"));
@@ -2151,17 +2151,15 @@ static int sd_revalidate_disk(struct gendisk *disk)
 
 	/*
 	 * We now have all cache related info, determine how we deal
-	 * with ordered requests.  Note that as the current SCSI
-	 * dispatch function can alter request order, we cannot use
-	 * QUEUE_ORDERED_TAG_* even when ordered tag is supported.
+	 * with flush requests.
 	 */
-	if (sdkp->WCE)
-		ordered = sdkp->DPOFUA
-			? QUEUE_ORDERED_DRAIN_FUA : QUEUE_ORDERED_DRAIN_FLUSH;
-	else
-		ordered = QUEUE_ORDERED_DRAIN;
+	if (sdkp->WCE) {
+		flush |= REQ_FLUSH;
+		if (sdkp->DPOFUA)
+			flush |= REQ_FUA;
+	}
 
-	blk_queue_ordered(sdkp->disk->queue, ordered);
+	blk_queue_flush(sdkp->disk->queue, flush);
 
 	set_capacity(disk, sdkp->capacity);
 	kfree(buffer);

fs/block_dev.c

@@ -370,7 +370,7 @@ int blkdev_fsync(struct file *filp, int datasync)
 	 */
 	mutex_unlock(&bd_inode->i_mutex);
 
-	error = blkdev_issue_flush(bdev, GFP_KERNEL, NULL, BLKDEV_IFL_WAIT);
+	error = blkdev_issue_flush(bdev, GFP_KERNEL, NULL);
 	if (error == -EOPNOTSUPP)
 		error = 0;
 

fs/btrfs/disk-io.c

@@ -2063,7 +2063,7 @@ static void btrfs_end_buffer_write_sync(struct buffer_head *bh, int uptodate)
 	if (uptodate) {
 		set_buffer_uptodate(bh);
 	} else {
-		if (!buffer_eopnotsupp(bh) && printk_ratelimit()) {
+		if (printk_ratelimit()) {
 			printk(KERN_WARNING "lost page write due to "
 					"I/O error on %s\n",
 				       bdevname(bh->b_bdev, b));
@@ -2200,21 +2200,10 @@ static int write_dev_supers(struct btrfs_device *device,
 			bh->b_end_io = btrfs_end_buffer_write_sync;
 		}
 
-		if (i == last_barrier && do_barriers && device->barriers) {
-			ret = submit_bh(WRITE_BARRIER, bh);
-			if (ret == -EOPNOTSUPP) {
-				printk("btrfs: disabling barriers on dev %s\n",
-				       device->name);
-				set_buffer_uptodate(bh);
-				device->barriers = 0;
-				/* one reference for submit_bh */
-				get_bh(bh);
-				lock_buffer(bh);
-				ret = submit_bh(WRITE_SYNC, bh);
-			}
-		} else {
+		if (i == last_barrier && do_barriers)
+			ret = submit_bh(WRITE_FLUSH_FUA, bh);
+		else
 			ret = submit_bh(WRITE_SYNC, bh);
-		}
 
 		if (ret)
 			errors++;

fs/btrfs/extent-tree.c

@@ -1695,8 +1695,7 @@ static int remove_extent_backref(struct btrfs_trans_handle *trans,
 static void btrfs_issue_discard(struct block_device *bdev,
 				u64 start, u64 len)
 {
-	blkdev_issue_discard(bdev, start >> 9, len >> 9, GFP_KERNEL,
-			BLKDEV_IFL_WAIT | BLKDEV_IFL_BARRIER);
+	blkdev_issue_discard(bdev, start >> 9, len >> 9, GFP_KERNEL, 0);
 }
 
 static int btrfs_discard_extent(struct btrfs_root *root, u64 bytenr,

fs/btrfs/volumes.c

@@ -398,7 +398,6 @@ static noinline int device_list_add(const char *path,
 		device->work.func = pending_bios_fn;
 		memcpy(device->uuid, disk_super->dev_item.uuid,
 		       BTRFS_UUID_SIZE);
-		device->barriers = 1;
 		spin_lock_init(&device->io_lock);
 		device->name = kstrdup(path, GFP_NOFS);
 		if (!device->name) {
@@ -462,7 +461,6 @@ static struct btrfs_fs_devices *clone_fs_devices(struct btrfs_fs_devices *orig)
 		device->devid = orig_dev->devid;
 		device->work.func = pending_bios_fn;
 		memcpy(device->uuid, orig_dev->uuid, sizeof(device->uuid));
-		device->barriers = 1;
 		spin_lock_init(&device->io_lock);
 		INIT_LIST_HEAD(&device->dev_list);
 		INIT_LIST_HEAD(&device->dev_alloc_list);
@@ -1489,7 +1487,6 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
 	trans = btrfs_start_transaction(root, 0);
 	lock_chunks(root);
 
-	device->barriers = 1;
 	device->writeable = 1;
 	device->work.func = pending_bios_fn;
 	generate_random_uuid(device->uuid);
@@ -3084,7 +3081,6 @@ static struct btrfs_device *add_missing_dev(struct btrfs_root *root,
 		return NULL;
 	list_add(&device->dev_list,
 		 &fs_devices->devices);
-	device->barriers = 1;
 	device->dev_root = root->fs_info->dev_root;
 	device->devid = devid;
 	device->work.func = pending_bios_fn;

fs/btrfs/volumes.h

@@ -42,7 +42,6 @@ struct btrfs_device {
 	int running_pending;
 	u64 generation;
 
-	int barriers;
 	int writeable;
 	int in_fs_metadata;
 

fs/buffer.c

@@ -156,7 +156,7 @@ void end_buffer_write_sync(struct buffer_head *bh, int uptodate)
 	if (uptodate) {
 		set_buffer_uptodate(bh);
 	} else {
-		if (!buffer_eopnotsupp(bh) && !quiet_error(bh)) {
+		if (!quiet_error(bh)) {
 			buffer_io_error(bh);
 			printk(KERN_WARNING "lost page write due to "
 					"I/O error on %s\n",
@@ -2891,7 +2891,6 @@ static void end_bio_bh_io_sync(struct bio *bio, int err)
 
 	if (err == -EOPNOTSUPP) {
 		set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
-		set_bit(BH_Eopnotsupp, &bh->b_state);
 	}
 
 	if (unlikely (test_bit(BIO_QUIET,&bio->bi_flags)))
@@ -3031,10 +3030,6 @@ int __sync_dirty_buffer(struct buffer_head *bh, int rw)
 		bh->b_end_io = end_buffer_write_sync;
 		ret = submit_bh(rw, bh);
 		wait_on_buffer(bh);
-		if (buffer_eopnotsupp(bh)) {
-			clear_buffer_eopnotsupp(bh);
-			ret = -EOPNOTSUPP;
-		}
 		if (!ret && !buffer_uptodate(bh))
 			ret = -EIO;
 	} else {

fs/ext3/fsync.c

@@ -90,7 +90,6 @@ int ext3_sync_file(struct file *file, int datasync)
 	 * storage
 	 */
 	if (needs_barrier)
-		blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL,
-				BLKDEV_IFL_WAIT);
+		blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
 	return ret;
 }

fs/ext4/fsync.c

@@ -128,10 +128,9 @@ int ext4_sync_file(struct file *file, int datasync)
 		    (journal->j_fs_dev != journal->j_dev) &&
 		    (journal->j_flags & JBD2_BARRIER))
 			blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL,
-					NULL, BLKDEV_IFL_WAIT);
+					NULL);
 		ret = jbd2_log_wait_commit(journal, commit_tid);
 	} else if (journal->j_flags & JBD2_BARRIER)
-		blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL,
-			BLKDEV_IFL_WAIT);
+		blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
 	return ret;
 }

fs/ext4/mballoc.c

@@ -2566,7 +2566,7 @@ static inline void ext4_issue_discard(struct super_block *sb,
 	discard_block = block + ext4_group_first_block_no(sb, block_group);
 	trace_ext4_discard_blocks(sb,
 			(unsigned long long) discard_block, count);
-	ret = sb_issue_discard(sb, discard_block, count);
+	ret = sb_issue_discard(sb, discard_block, count, GFP_NOFS, 0);
 	if (ret == EOPNOTSUPP) {
 		ext4_warning(sb, "discard not supported, disabling");
 		clear_opt(EXT4_SB(sb)->s_mount_opt, DISCARD);

fs/fat/fatent.c

@@ -577,7 +577,8 @@ int fat_free_clusters(struct inode *inode, int cluster)
 
 				sb_issue_discard(sb,
 					fat_clus_to_blknr(sbi, first_cl),
-					nr_clus * sbi->sec_per_clus);
+					nr_clus * sbi->sec_per_clus,
+					GFP_NOFS, 0);
 
 				first_cl = cluster;
 			}

fs/fat/misc.c

@@ -255,10 +255,7 @@ int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs)
 
 	for (i = 0; i < nr_bhs; i++) {
 		wait_on_buffer(bhs[i]);
-		if (buffer_eopnotsupp(bhs[i])) {
-			clear_buffer_eopnotsupp(bhs[i]);
-			err = -EOPNOTSUPP;
-		} else if (!err && !buffer_uptodate(bhs[i]))
+		if (!err && !buffer_uptodate(bhs[i]))
 			err = -EIO;
 	}
 	return err;

fs/gfs2/log.c

@@ -592,22 +592,13 @@ static void log_write_header(struct gfs2_sbd *sdp, u32 flags, int pull)
 	lh->lh_hash = cpu_to_be32(hash);
 
 	bh->b_end_io = end_buffer_write_sync;
-	if (test_bit(SDF_NOBARRIERS, &sdp->sd_flags))
-		goto skip_barrier;
 	get_bh(bh);
-	submit_bh(WRITE_BARRIER | REQ_META, bh);
-	wait_on_buffer(bh);
-	if (buffer_eopnotsupp(bh)) {
-		clear_buffer_eopnotsupp(bh);
-		set_buffer_uptodate(bh);
-		fs_info(sdp, "barrier sync failed - disabling barriers\n");
-		set_bit(SDF_NOBARRIERS, &sdp->sd_flags);
-		lock_buffer(bh);
-skip_barrier:
-		get_bh(bh);
+	if (test_bit(SDF_NOBARRIERS, &sdp->sd_flags))
 		submit_bh(WRITE_SYNC | REQ_META, bh);
-		wait_on_buffer(bh);
-	}
+	else
+		submit_bh(WRITE_FLUSH_FUA | REQ_META, bh);
+	wait_on_buffer(bh);
+
 	if (!buffer_uptodate(bh))
 		gfs2_io_error_bh(sdp, bh);
 	brelse(bh);

fs/gfs2/rgrp.c

@@ -866,8 +866,7 @@ static void gfs2_rgrp_send_discards(struct gfs2_sbd *sdp, u64 offset,
 				if ((start + nr_sects) != blk) {
 					rv = blkdev_issue_discard(bdev, start,
 							    nr_sects, GFP_NOFS,
-							    BLKDEV_IFL_WAIT |
-							    BLKDEV_IFL_BARRIER);
+							    0);
 					if (rv)
 						goto fail;
 					nr_sects = 0;
@@ -881,8 +880,7 @@ static void gfs2_rgrp_send_discards(struct gfs2_sbd *sdp, u64 offset,
 		}
 	}
 	if (nr_sects) {
-		rv = blkdev_issue_discard(bdev, start, nr_sects, GFP_NOFS,
-					 BLKDEV_IFL_WAIT | BLKDEV_IFL_BARRIER);
+		rv = blkdev_issue_discard(bdev, start, nr_sects, GFP_NOFS, 0);
 		if (rv)
 			goto fail;
 	}

fs/jbd/commit.c

@@ -137,34 +137,10 @@ static int journal_write_commit_record(journal_t *journal,
 	JBUFFER_TRACE(descriptor, "write commit block");
 	set_buffer_dirty(bh);
 
-	if (journal->j_flags & JFS_BARRIER) {
-		ret = __sync_dirty_buffer(bh, WRITE_SYNC | WRITE_BARRIER);
-
-		/*
-		 * Is it possible for another commit to fail at roughly
-		 * the same time as this one?  If so, we don't want to
-		 * trust the barrier flag in the super, but instead want
-		 * to remember if we sent a barrier request
-		 */
-		if (ret == -EOPNOTSUPP) {
-			char b[BDEVNAME_SIZE];
-
-			printk(KERN_WARNING
-				"JBD: barrier-based sync failed on %s - "
-				"disabling barriers\n",
-				bdevname(journal->j_dev, b));
-			spin_lock(&journal->j_state_lock);
-			journal->j_flags &= ~JFS_BARRIER;
-			spin_unlock(&journal->j_state_lock);
-
-			/* And try again, without the barrier */
-			set_buffer_uptodate(bh);
-			set_buffer_dirty(bh);
-			ret = sync_dirty_buffer(bh);
-		}
-	} else {
+	if (journal->j_flags & JFS_BARRIER)
+		ret = __sync_dirty_buffer(bh, WRITE_SYNC | WRITE_FLUSH_FUA);
+	else
 		ret = sync_dirty_buffer(bh);
-	}
 
 	put_bh(bh);		/* One for getblk() */
 	journal_put_journal_head(descriptor);

fs/jbd2/checkpoint.c

@@ -532,8 +532,7 @@ int jbd2_cleanup_journal_tail(journal_t *journal)
 	 */
 	if ((journal->j_fs_dev != journal->j_dev) &&
 	    (journal->j_flags & JBD2_BARRIER))
-		blkdev_issue_flush(journal->j_fs_dev, GFP_KERNEL, NULL,
-			BLKDEV_IFL_WAIT);
+		blkdev_issue_flush(journal->j_fs_dev, GFP_KERNEL, NULL);
 	if (!(journal->j_flags & JBD2_ABORT))
 		jbd2_journal_update_superblock(journal, 1);
 	return 0;

fs/jbd2/commit.c

@@ -134,25 +134,11 @@ static int journal_submit_commit_record(journal_t *journal,
 
 	if (journal->j_flags & JBD2_BARRIER &&
 	    !JBD2_HAS_INCOMPAT_FEATURE(journal,
-				       JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) {
-		ret = submit_bh(WRITE_SYNC_PLUG | WRITE_BARRIER, bh);
-		if (ret == -EOPNOTSUPP) {
-			printk(KERN_WARNING
-			       "JBD2: Disabling barriers on %s, "
-			       "not supported by device\n", journal->j_devname);
-			write_lock(&journal->j_state_lock);
-			journal->j_flags &= ~JBD2_BARRIER;
-			write_unlock(&journal->j_state_lock);
-
-			/* And try again, without the barrier */
-			lock_buffer(bh);
-			set_buffer_uptodate(bh);
-			clear_buffer_dirty(bh);
-			ret = submit_bh(WRITE_SYNC_PLUG, bh);
-		}
-	} else {
+				       JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT))
+		ret = submit_bh(WRITE_SYNC_PLUG | WRITE_FLUSH_FUA, bh);
+	else
 		ret = submit_bh(WRITE_SYNC_PLUG, bh);
-	}
+
 	*cbh = bh;
 	return ret;
 }
@@ -166,29 +152,8 @@ static int journal_wait_on_commit_record(journal_t *journal,
 {
 	int ret = 0;
 
-retry:
 	clear_buffer_dirty(bh);
 	wait_on_buffer(bh);
-	if (buffer_eopnotsupp(bh) && (journal->j_flags & JBD2_BARRIER)) {
-		printk(KERN_WARNING
-		       "JBD2: %s: disabling barries on %s - not supported "
-		       "by device\n", __func__, journal->j_devname);
-		write_lock(&journal->j_state_lock);
-		journal->j_flags &= ~JBD2_BARRIER;
-		write_unlock(&journal->j_state_lock);
-
-		lock_buffer(bh);
-		clear_buffer_dirty(bh);
-		set_buffer_uptodate(bh);
-		bh->b_end_io = journal_end_buffer_io_sync;
-
-		ret = submit_bh(WRITE_SYNC_PLUG, bh);
-		if (ret) {
-			unlock_buffer(bh);
-			return ret;
-		}
-		goto retry;
-	}
 
 	if (unlikely(!buffer_uptodate(bh)))
 		ret = -EIO;
@@ -701,6 +666,16 @@ void jbd2_journal_commit_transaction(journal_t *journal)
 		}
 	}
 
+	err = journal_finish_inode_data_buffers(journal, commit_transaction);
+	if (err) {
+		printk(KERN_WARNING
+			"JBD2: Detected IO errors while flushing file data "
+		       "on %s\n", journal->j_devname);
+		if (journal->j_flags & JBD2_ABORT_ON_SYNCDATA_ERR)
+			jbd2_journal_abort(journal, err);
+		err = 0;
+	}
+
 	/* 
 	 * If the journal is not located on the file system device,
 	 * then we must flush the file system device before we issue
@@ -709,8 +684,7 @@ void jbd2_journal_commit_transaction(journal_t *journal)
 	if (commit_transaction->t_flushed_data_blocks &&
 	    (journal->j_fs_dev != journal->j_dev) &&
 	    (journal->j_flags & JBD2_BARRIER))
-		blkdev_issue_flush(journal->j_fs_dev, GFP_KERNEL, NULL,
-			BLKDEV_IFL_WAIT);
+		blkdev_issue_flush(journal->j_fs_dev, GFP_KERNEL, NULL);
 
 	/* Done it all: now write the commit record asynchronously. */
 	if (JBD2_HAS_INCOMPAT_FEATURE(journal,
@@ -719,19 +693,6 @@ void jbd2_journal_commit_transaction(journal_t *journal)
 						 &cbh, crc32_sum);
 		if (err)
 			__jbd2_journal_abort_hard(journal);
-		if (journal->j_flags & JBD2_BARRIER)
-			blkdev_issue_flush(journal->j_dev, GFP_KERNEL, NULL,
-				BLKDEV_IFL_WAIT);
-	}
-
-	err = journal_finish_inode_data_buffers(journal, commit_transaction);
-	if (err) {
-		printk(KERN_WARNING
-			"JBD2: Detected IO errors while flushing file data "
-		       "on %s\n", journal->j_devname);
-		if (journal->j_flags & JBD2_ABORT_ON_SYNCDATA_ERR)
-			jbd2_journal_abort(journal, err);
-		err = 0;
 	}
 
 	/* Lo and behold: we have just managed to send a transaction to
@@ -845,6 +806,11 @@ void jbd2_journal_commit_transaction(journal_t *journal)
 	}
 	if (!err && !is_journal_aborted(journal))
 		err = journal_wait_on_commit_record(journal, cbh);
+	if (JBD2_HAS_INCOMPAT_FEATURE(journal,
+				      JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT) &&
+	    journal->j_flags & JBD2_BARRIER) {
+		blkdev_issue_flush(journal->j_dev, GFP_KERNEL, NULL);
+	}
 
 	if (err)
 		jbd2_journal_abort(journal, err);

fs/nilfs2/super.c

@@ -177,17 +177,9 @@ static int nilfs_sync_super(struct nilfs_sb_info *sbi, int flag)
 
  retry:
 	set_buffer_dirty(nilfs->ns_sbh[0]);
-
 	if (nilfs_test_opt(sbi, BARRIER)) {
 		err = __sync_dirty_buffer(nilfs->ns_sbh[0],
-					  WRITE_SYNC | WRITE_BARRIER);
-		if (err == -EOPNOTSUPP) {
-			nilfs_warning(sbi->s_super, __func__,
-				      "barrier-based sync failed. "
-				      "disabling barriers\n");
-			nilfs_clear_opt(sbi, BARRIER);
-			goto retry;
-		}
+					  WRITE_SYNC | WRITE_FLUSH_FUA);
 	} else {
 		err = sync_dirty_buffer(nilfs->ns_sbh[0]);
 	}

fs/nilfs2/the_nilfs.c

@@ -775,9 +775,7 @@ int nilfs_discard_segments(struct the_nilfs *nilfs, __u64 *segnump,
 			ret = blkdev_issue_discard(nilfs->ns_bdev,
 						   start * sects_per_block,
 						   nblocks * sects_per_block,
-						   GFP_NOFS,
-						   BLKDEV_IFL_WAIT |
-						   BLKDEV_IFL_BARRIER);
+						   GFP_NOFS, 0);
 			if (ret < 0)
 				return ret;
 			nblocks = 0;
@@ -787,8 +785,7 @@ int nilfs_discard_segments(struct the_nilfs *nilfs, __u64 *segnump,
 		ret = blkdev_issue_discard(nilfs->ns_bdev,
 					   start * sects_per_block,
 					   nblocks * sects_per_block,
-					   GFP_NOFS,
-					  BLKDEV_IFL_WAIT | BLKDEV_IFL_BARRIER);
+					   GFP_NOFS, 0);
 	return ret;
 }
 

fs/reiserfs/file.c

@@ -152,8 +152,7 @@ static int reiserfs_sync_file(struct file *filp, int datasync)
 	barrier_done = reiserfs_commit_for_inode(inode);
 	reiserfs_write_unlock(inode->i_sb);
 	if (barrier_done != 1 && reiserfs_barrier_flush(inode->i_sb))
-		blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL, 
-			BLKDEV_IFL_WAIT);
+		blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
 	if (barrier_done < 0)
 		return barrier_done;
 	return (err < 0) ? -EIO : 0;

fs/reiserfs/journal.c

@@ -138,13 +138,6 @@ static int reiserfs_clean_and_file_buffer(struct buffer_head *bh)
 	return 0;
 }
 
-static void disable_barrier(struct super_block *s)
-{
-	REISERFS_SB(s)->s_mount_opt &= ~(1 << REISERFS_BARRIER_FLUSH);
-	printk("reiserfs: disabling flush barriers on %s\n",
-	       reiserfs_bdevname(s));
-}
-
 static struct reiserfs_bitmap_node *allocate_bitmap_node(struct super_block
 							 *sb)
 {
@@ -677,30 +670,6 @@ static void submit_ordered_buffer(struct buffer_head *bh)
 	submit_bh(WRITE, bh);
 }
 
-static int submit_barrier_buffer(struct buffer_head *bh)
-{
-	get_bh(bh);
-	bh->b_end_io = reiserfs_end_ordered_io;
-	clear_buffer_dirty(bh);
-	if (!buffer_uptodate(bh))
-		BUG();
-	return submit_bh(WRITE_BARRIER, bh);
-}
-
-static void check_barrier_completion(struct super_block *s,
-				     struct buffer_head *bh)
-{
-	if (buffer_eopnotsupp(bh)) {
-		clear_buffer_eopnotsupp(bh);
-		disable_barrier(s);
-		set_buffer_uptodate(bh);
-		set_buffer_dirty(bh);
-		reiserfs_write_unlock(s);
-		sync_dirty_buffer(bh);
-		reiserfs_write_lock(s);
-	}
-}
-
 #define CHUNK_SIZE 32
 struct buffer_chunk {
 	struct buffer_head *bh[CHUNK_SIZE];
@@ -1009,7 +978,6 @@ static int flush_commit_list(struct super_block *s,
 	struct buffer_head *tbh = NULL;
 	unsigned int trans_id = jl->j_trans_id;
 	struct reiserfs_journal *journal = SB_JOURNAL(s);
-	int barrier = 0;
 	int retval = 0;
 	int write_len;
 
@@ -1094,24 +1062,6 @@ static int flush_commit_list(struct super_block *s,
 	}
 	atomic_dec(&journal->j_async_throttle);
 
-	/* We're skipping the commit if there's an error */
-	if (retval || reiserfs_is_journal_aborted(journal))
-		barrier = 0;
-
-	/* wait on everything written so far before writing the commit
-	 * if we are in barrier mode, send the commit down now
-	 */
-	barrier = reiserfs_barrier_flush(s);
-	if (barrier) {
-		int ret;
-		lock_buffer(jl->j_commit_bh);
-		ret = submit_barrier_buffer(jl->j_commit_bh);
-		if (ret == -EOPNOTSUPP) {
-			set_buffer_uptodate(jl->j_commit_bh);
-			disable_barrier(s);
-			barrier = 0;
-		}
-	}
 	for (i = 0; i < (jl->j_len + 1); i++) {
 		bn = SB_ONDISK_JOURNAL_1st_BLOCK(s) +
 		    (jl->j_start + i) % SB_ONDISK_JOURNAL_SIZE(s);
@@ -1143,27 +1093,22 @@ static int flush_commit_list(struct super_block *s,
 
 	BUG_ON(atomic_read(&(jl->j_commit_left)) != 1);
 
-	if (!barrier) {
-		/* If there was a write error in the journal - we can't commit
-		 * this transaction - it will be invalid and, if successful,
-		 * will just end up propagating the write error out to
-		 * the file system. */
-		if (likely(!retval && !reiserfs_is_journal_aborted (journal))) {
-			if (buffer_dirty(jl->j_commit_bh))
-				BUG();
-			mark_buffer_dirty(jl->j_commit_bh) ;
-			reiserfs_write_unlock(s);
-			sync_dirty_buffer(jl->j_commit_bh) ;
-			reiserfs_write_lock(s);
-		}
-	} else {
+	/* If there was a write error in the journal - we can't commit
+	 * this transaction - it will be invalid and, if successful,
+	 * will just end up propagating the write error out to
+	 * the file system. */
+	if (likely(!retval && !reiserfs_is_journal_aborted (journal))) {
+		if (buffer_dirty(jl->j_commit_bh))
+			BUG();
+		mark_buffer_dirty(jl->j_commit_bh) ;
 		reiserfs_write_unlock(s);
-		wait_on_buffer(jl->j_commit_bh);
+		if (reiserfs_barrier_flush(s))
+			__sync_dirty_buffer(jl->j_commit_bh, WRITE_FLUSH_FUA);
+		else
+			sync_dirty_buffer(jl->j_commit_bh);
 		reiserfs_write_lock(s);
 	}
 
-	check_barrier_completion(s, jl->j_commit_bh);
-
 	/* If there was a write error in the journal - we can't commit this
 	 * transaction - it will be invalid and, if successful, will just end
 	 * up propagating the write error out to the filesystem. */
@@ -1319,26 +1264,15 @@ static int _update_journal_header_block(struct super_block *sb,
 		jh->j_first_unflushed_offset = cpu_to_le32(offset);
 		jh->j_mount_id = cpu_to_le32(journal->j_mount_id);
 
-		if (reiserfs_barrier_flush(sb)) {
-			int ret;
-			lock_buffer(journal->j_header_bh);
-			ret = submit_barrier_buffer(journal->j_header_bh);
-			if (ret == -EOPNOTSUPP) {
-				set_buffer_uptodate(journal->j_header_bh);
-				disable_barrier(sb);
-				goto sync;
-			}
-			reiserfs_write_unlock(sb);
-			wait_on_buffer(journal->j_header_bh);
-			reiserfs_write_lock(sb);
-			check_barrier_completion(sb, journal->j_header_bh);
-		} else {
-		      sync:
-			set_buffer_dirty(journal->j_header_bh);
-			reiserfs_write_unlock(sb);
+		set_buffer_dirty(journal->j_header_bh);
+		reiserfs_write_unlock(sb);
+
+		if (reiserfs_barrier_flush(sb))
+			__sync_dirty_buffer(journal->j_header_bh, WRITE_FLUSH_FUA);
+		else
 			sync_dirty_buffer(journal->j_header_bh);
-			reiserfs_write_lock(sb);
-		}
+
+		reiserfs_write_lock(sb);
 		if (!buffer_uptodate(journal->j_header_bh)) {
 			reiserfs_warning(sb, "journal-837",
 					 "IO error during journal replay");

fs/xfs/linux-2.6/xfs_buf.c

@@ -924,19 +924,7 @@ xfs_buf_iodone_work(
 	xfs_buf_t		*bp =
 		container_of(work, xfs_buf_t, b_iodone_work);
 
-	/*
-	 * We can get an EOPNOTSUPP to ordered writes.  Here we clear the
-	 * ordered flag and reissue them.  Because we can't tell the higher
-	 * layers directly that they should not issue ordered I/O anymore, they
-	 * need to check if the _XFS_BARRIER_FAILED flag was set during I/O completion.
-	 */
-	if ((bp->b_error == EOPNOTSUPP) &&
-	    (bp->b_flags & (XBF_ORDERED|XBF_ASYNC)) == (XBF_ORDERED|XBF_ASYNC)) {
-		trace_xfs_buf_ordered_retry(bp, _RET_IP_);
-		bp->b_flags &= ~XBF_ORDERED;
-		bp->b_flags |= _XFS_BARRIER_FAILED;
-		xfs_buf_iorequest(bp);
-	} else if (bp->b_iodone)
+	if (bp->b_iodone)
 		(*(bp->b_iodone))(bp);
 	else if (bp->b_flags & XBF_ASYNC)
 		xfs_buf_relse(bp);
@@ -1195,7 +1183,7 @@ _xfs_buf_ioapply(
 
 	if (bp->b_flags & XBF_ORDERED) {
 		ASSERT(!(bp->b_flags & XBF_READ));
-		rw = WRITE_BARRIER;
+		rw = WRITE_FLUSH_FUA;
 	} else if (bp->b_flags & XBF_LOG_BUFFER) {
 		ASSERT(!(bp->b_flags & XBF_READ_AHEAD));
 		bp->b_flags &= ~_XBF_RUN_QUEUES;

fs/xfs/linux-2.6/xfs_buf.h

@@ -86,14 +86,6 @@ typedef enum {
  */
 #define _XBF_PAGE_LOCKED	(1 << 22)
 
-/*
- * If we try a barrier write, but it fails we have to communicate
- * this to the upper layers.  Unfortunately b_error gets overwritten
- * when the buffer is re-issued so we have to add another flag to
- * keep this information.
- */
-#define _XFS_BARRIER_FAILED	(1 << 23)
-
 typedef unsigned int xfs_buf_flags_t;
 
 #define XFS_BUF_FLAGS \
@@ -114,8 +106,7 @@ typedef unsigned int xfs_buf_flags_t;
 	{ _XBF_PAGES,		"PAGES" }, \
 	{ _XBF_RUN_QUEUES,	"RUN_QUEUES" }, \
 	{ _XBF_DELWRI_Q,	"DELWRI_Q" }, \
-	{ _XBF_PAGE_LOCKED,	"PAGE_LOCKED" }, \
-	{ _XFS_BARRIER_FAILED,	"BARRIER_FAILED" }
+	{ _XBF_PAGE_LOCKED,	"PAGE_LOCKED" }
 
 
 typedef enum {

fs/xfs/linux-2.6/xfs_super.c

@@ -693,8 +693,7 @@ void
 xfs_blkdev_issue_flush(
 	xfs_buftarg_t		*buftarg)
 {
-	blkdev_issue_flush(buftarg->bt_bdev, GFP_KERNEL, NULL,
-			BLKDEV_IFL_WAIT);
+	blkdev_issue_flush(buftarg->bt_bdev, GFP_KERNEL, NULL);
 }
 
 STATIC void

fs/xfs/linux-2.6/xfs_trace.h

@@ -325,7 +325,6 @@ DEFINE_BUF_EVENT(xfs_buf_lock);
 DEFINE_BUF_EVENT(xfs_buf_lock_done);
 DEFINE_BUF_EVENT(xfs_buf_cond_lock);
 DEFINE_BUF_EVENT(xfs_buf_unlock);
-DEFINE_BUF_EVENT(xfs_buf_ordered_retry);
 DEFINE_BUF_EVENT(xfs_buf_iowait);
 DEFINE_BUF_EVENT(xfs_buf_iowait_done);
 DEFINE_BUF_EVENT(xfs_buf_delwri_queue);

fs/xfs/xfs_log.c

@@ -916,19 +916,6 @@ xlog_iodone(xfs_buf_t *bp)
 	aborted = 0;
 	l = iclog->ic_log;
 
-	/*
-	 * If the _XFS_BARRIER_FAILED flag was set by a lower
-	 * layer, it means the underlying device no longer supports
-	 * barrier I/O. Warn loudly and turn off barriers.
-	 */
-	if (bp->b_flags & _XFS_BARRIER_FAILED) {
-		bp->b_flags &= ~_XFS_BARRIER_FAILED;
-		l->l_mp->m_flags &= ~XFS_MOUNT_BARRIER;
-		xfs_fs_cmn_err(CE_WARN, l->l_mp,
-				"xlog_iodone: Barriers are no longer supported"
-				" by device. Disabling barriers\n");
-	}
-
 	/*
 	 * Race to shutdown the filesystem if we see an error.
 	 */

include/linux/blk_types.h

@@ -146,7 +146,6 @@ enum rq_flag_bits {
 	__REQ_FAILED,		/* set if the request failed */
 	__REQ_QUIET,		/* don't worry about errors */
 	__REQ_PREEMPT,		/* set for "ide_preempt" requests */
-	__REQ_ORDERED_COLOR,	/* is before or after barrier */
 	__REQ_ALLOCED,		/* request came from our alloc pool */
 	__REQ_COPY_USER,	/* contains copies of user pages */
 	__REQ_FLUSH,		/* request for cache flush */
@@ -170,7 +169,8 @@ enum rq_flag_bits {
 	(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_META | REQ_DISCARD | REQ_NOIDLE | REQ_FLUSH | REQ_FUA)
+#define REQ_CLONE_MASK		REQ_COMMON_MASK
 
 #define REQ_UNPLUG		(1 << __REQ_UNPLUG)
 #define REQ_RAHEAD		(1 << __REQ_RAHEAD)
@@ -187,7 +187,6 @@ enum rq_flag_bits {
 #define REQ_FAILED		(1 << __REQ_FAILED)
 #define REQ_QUIET		(1 << __REQ_QUIET)
 #define REQ_PREEMPT		(1 << __REQ_PREEMPT)
-#define REQ_ORDERED_COLOR	(1 << __REQ_ORDERED_COLOR)
 #define REQ_ALLOCED		(1 << __REQ_ALLOCED)
 #define REQ_COPY_USER		(1 << __REQ_COPY_USER)
 #define REQ_FLUSH		(1 << __REQ_FLUSH)

include/linux/blkdev.h

@@ -360,12 +360,14 @@ struct request_queue
 	struct blk_trace	*blk_trace;
 #endif
 	/*
-	 * reserved for flush operations
+	 * for flush operations
 	 */
-	unsigned int		ordered, next_ordered, ordseq;
-	int			orderr, ordcolor;
-	struct request		pre_flush_rq, bar_rq, post_flush_rq;
-	struct request		*orig_bar_rq;
+	unsigned int		flush_flags;
+	unsigned int		flush_seq;
+	int			flush_err;
+	struct request		flush_rq;
+	struct request		*orig_flush_rq;
+	struct list_head	pending_flushes;
 
 	struct mutex		sysfs_lock;
 
@@ -472,56 +474,6 @@ static inline void queue_flag_clear(unsigned int flag, struct request_queue *q)
 	__clear_bit(flag, &q->queue_flags);
 }
 
-enum {
-	/*
-	 * Hardbarrier is supported with one of the following methods.
-	 *
-	 * NONE		: hardbarrier unsupported
-	 * DRAIN	: ordering by draining is enough
-	 * DRAIN_FLUSH	: ordering by draining w/ pre and post flushes
-	 * DRAIN_FUA	: ordering by draining w/ pre flush and FUA write
-	 * TAG		: ordering by tag is enough
-	 * TAG_FLUSH	: ordering by tag w/ pre and post flushes
-	 * TAG_FUA	: ordering by tag w/ pre flush and FUA write
-	 */
-	QUEUE_ORDERED_BY_DRAIN		= 0x01,
-	QUEUE_ORDERED_BY_TAG		= 0x02,
-	QUEUE_ORDERED_DO_PREFLUSH	= 0x10,
-	QUEUE_ORDERED_DO_BAR		= 0x20,
-	QUEUE_ORDERED_DO_POSTFLUSH	= 0x40,
-	QUEUE_ORDERED_DO_FUA		= 0x80,
-
-	QUEUE_ORDERED_NONE		= 0x00,
-
-	QUEUE_ORDERED_DRAIN		= QUEUE_ORDERED_BY_DRAIN |
-					  QUEUE_ORDERED_DO_BAR,
-	QUEUE_ORDERED_DRAIN_FLUSH	= QUEUE_ORDERED_DRAIN |
-					  QUEUE_ORDERED_DO_PREFLUSH |
-					  QUEUE_ORDERED_DO_POSTFLUSH,
-	QUEUE_ORDERED_DRAIN_FUA		= QUEUE_ORDERED_DRAIN |
-					  QUEUE_ORDERED_DO_PREFLUSH |
-					  QUEUE_ORDERED_DO_FUA,
-
-	QUEUE_ORDERED_TAG		= QUEUE_ORDERED_BY_TAG |
-					  QUEUE_ORDERED_DO_BAR,
-	QUEUE_ORDERED_TAG_FLUSH		= QUEUE_ORDERED_TAG |
-					  QUEUE_ORDERED_DO_PREFLUSH |
-					  QUEUE_ORDERED_DO_POSTFLUSH,
-	QUEUE_ORDERED_TAG_FUA		= QUEUE_ORDERED_TAG |
-					  QUEUE_ORDERED_DO_PREFLUSH |
-					  QUEUE_ORDERED_DO_FUA,
-
-	/*
-	 * Ordered operation sequence
-	 */
-	QUEUE_ORDSEQ_STARTED	= 0x01,	/* flushing in progress */
-	QUEUE_ORDSEQ_DRAIN	= 0x02,	/* waiting for the queue to be drained */
-	QUEUE_ORDSEQ_PREFLUSH	= 0x04,	/* pre-flushing in progress */
-	QUEUE_ORDSEQ_BAR	= 0x08,	/* original barrier req in progress */
-	QUEUE_ORDSEQ_POSTFLUSH	= 0x10,	/* post-flushing in progress */
-	QUEUE_ORDSEQ_DONE	= 0x20,
-};
-
 #define blk_queue_plugged(q)	test_bit(QUEUE_FLAG_PLUGGED, &(q)->queue_flags)
 #define blk_queue_tagged(q)	test_bit(QUEUE_FLAG_QUEUED, &(q)->queue_flags)
 #define blk_queue_stopped(q)	test_bit(QUEUE_FLAG_STOPPED, &(q)->queue_flags)
@@ -531,7 +483,6 @@ enum {
 #define blk_queue_nonrot(q)	test_bit(QUEUE_FLAG_NONROT, &(q)->queue_flags)
 #define blk_queue_io_stat(q)	test_bit(QUEUE_FLAG_IO_STAT, &(q)->queue_flags)
 #define blk_queue_add_random(q)	test_bit(QUEUE_FLAG_ADD_RANDOM, &(q)->queue_flags)
-#define blk_queue_flushing(q)	((q)->ordseq)
 #define blk_queue_stackable(q)	\
 	test_bit(QUEUE_FLAG_STACKABLE, &(q)->queue_flags)
 #define blk_queue_discard(q)	test_bit(QUEUE_FLAG_DISCARD, &(q)->queue_flags)
@@ -602,7 +553,8 @@ 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_NOMERGE | REQ_STARTED | REQ_HARDBARRIER | REQ_SOFTBARRIER | \
+	 REQ_FLUSH | REQ_FUA)
 #define rq_mergeable(rq)	\
 	(!((rq)->cmd_flags & RQ_NOMERGE_FLAGS) && \
 	 (((rq)->cmd_flags & REQ_DISCARD) || \
@@ -891,12 +843,8 @@ extern void blk_queue_update_dma_alignment(struct request_queue *, int);
 extern void blk_queue_softirq_done(struct request_queue *, softirq_done_fn *);
 extern void blk_queue_rq_timed_out(struct request_queue *, rq_timed_out_fn *);
 extern void blk_queue_rq_timeout(struct request_queue *, unsigned int);
+extern void blk_queue_flush(struct request_queue *q, unsigned int flush);
 extern struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev);
-extern int blk_queue_ordered(struct request_queue *, unsigned);
-extern bool blk_do_ordered(struct request_queue *, struct request **);
-extern unsigned blk_ordered_cur_seq(struct request_queue *);
-extern unsigned blk_ordered_req_seq(struct request *);
-extern bool blk_ordered_complete_seq(struct request_queue *, unsigned, int);
 
 extern int blk_rq_map_sg(struct request_queue *, struct request *, struct scatterlist *);
 extern void blk_dump_rq_flags(struct request *, char *);
@@ -929,27 +877,20 @@ static inline struct request *blk_map_queue_find_tag(struct blk_queue_tag *bqt,
 		return NULL;
 	return bqt->tag_index[tag];
 }
-enum{
-	BLKDEV_WAIT,	/* wait for completion */
-	BLKDEV_BARRIER,	/* issue request with barrier */
-	BLKDEV_SECURE,	/* secure discard */
-};
-#define BLKDEV_IFL_WAIT		(1 << BLKDEV_WAIT)
-#define BLKDEV_IFL_BARRIER	(1 << BLKDEV_BARRIER)
-#define BLKDEV_IFL_SECURE	(1 << BLKDEV_SECURE)
-extern int blkdev_issue_flush(struct block_device *, gfp_t, sector_t *,
-			unsigned long);
+
+#define BLKDEV_DISCARD_SECURE  0x01    /* secure discard */
+
+extern int blkdev_issue_flush(struct block_device *, gfp_t, sector_t *);
 extern int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 		sector_t nr_sects, gfp_t gfp_mask, unsigned long flags);
 extern int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
-			sector_t nr_sects, gfp_t gfp_mask, unsigned long flags);
-static inline int sb_issue_discard(struct super_block *sb,
-				   sector_t block, sector_t nr_blocks)
-{
-	block <<= (sb->s_blocksize_bits - 9);
-	nr_blocks <<= (sb->s_blocksize_bits - 9);
-	return blkdev_issue_discard(sb->s_bdev, block, nr_blocks, GFP_NOFS,
-				   BLKDEV_IFL_WAIT | BLKDEV_IFL_BARRIER);
+			sector_t nr_sects, gfp_t gfp_mask);
+static inline int sb_issue_discard(struct super_block *sb, sector_t block,
+		sector_t nr_blocks, gfp_t gfp_mask, unsigned long flags)
+{
+	return blkdev_issue_discard(sb->s_bdev, block << (sb->s_blocksize_bits - 9),
+				    nr_blocks << (sb->s_blocksize_bits - 9),
+				    gfp_mask, flags);
 }
 
 extern int blk_verify_command(unsigned char *cmd, fmode_t has_write_perm);

include/linux/buffer_head.h

@@ -32,7 +32,6 @@ enum bh_state_bits {
 	BH_Delay,	/* Buffer is not yet allocated on disk */
 	BH_Boundary,	/* Block is followed by a discontiguity */
 	BH_Write_EIO,	/* I/O error on write */
-	BH_Eopnotsupp,	/* operation not supported (barrier) */
 	BH_Unwritten,	/* Buffer is allocated on disk but not written */
 	BH_Quiet,	/* Buffer Error Prinks to be quiet */
 
@@ -124,7 +123,6 @@ BUFFER_FNS(Async_Write, async_write)
 BUFFER_FNS(Delay, delay)
 BUFFER_FNS(Boundary, boundary)
 BUFFER_FNS(Write_EIO, write_io_error)
-BUFFER_FNS(Eopnotsupp, eopnotsupp)
 BUFFER_FNS(Unwritten, unwritten)
 
 #define bh_offset(bh)		((unsigned long)(bh)->b_data & ~PAGE_MASK)

include/linux/fs.h

@@ -135,12 +135,12 @@ struct inodes_stat_t {
  *			immediately after submission. The write equivalent
  *			of READ_SYNC.
  * WRITE_ODIRECT_PLUG	Special case write for O_DIRECT only.
- * WRITE_BARRIER	Like WRITE_SYNC, but tells the block layer that all
- *			previously submitted writes must be safely on storage
- *			before this one is started. Also guarantees that when
- *			this write is complete, it itself is also safely on
- *			storage. Prevents reordering of writes on both sides
- *			of this IO.
+ * WRITE_FLUSH		Like WRITE_SYNC but with preceding cache flush.
+ * WRITE_FUA		Like WRITE_SYNC but data is guaranteed to be on
+ *			non-volatile media on completion.
+ * WRITE_FLUSH_FUA	Combination of WRITE_FLUSH and FUA. The IO is preceded
+ *			by a cache flush and data is guaranteed to be on
+ *			non-volatile media on completion.
  *
  */
 #define RW_MASK			REQ_WRITE
@@ -156,16 +156,12 @@ struct inodes_stat_t {
 #define WRITE_SYNC		(WRITE | REQ_SYNC | REQ_NOIDLE | REQ_UNPLUG)
 #define WRITE_ODIRECT_PLUG	(WRITE | REQ_SYNC)
 #define WRITE_META		(WRITE | REQ_META)
-#define WRITE_BARRIER		(WRITE | REQ_SYNC | REQ_NOIDLE | REQ_UNPLUG | \
-				 REQ_HARDBARRIER)
-
-/*
- * These aren't really reads or writes, they pass down information about
- * parts of device that are now unused by the file system.
- */
-#define DISCARD_NOBARRIER	(WRITE | REQ_DISCARD)
-#define DISCARD_BARRIER		(WRITE | REQ_DISCARD | REQ_HARDBARRIER)
-#define DISCARD_SECURE		(DISCARD_NOBARRIER | REQ_SECURE)
+#define WRITE_FLUSH		(WRITE | REQ_SYNC | REQ_NOIDLE | REQ_UNPLUG | \
+				 REQ_FLUSH)
+#define WRITE_FUA		(WRITE | REQ_SYNC | REQ_NOIDLE | REQ_UNPLUG | \
+				 REQ_FUA)
+#define WRITE_FLUSH_FUA		(WRITE | REQ_SYNC | REQ_NOIDLE | REQ_UNPLUG | \
+				 REQ_FLUSH | REQ_FUA)
 
 #define SEL_IN		1
 #define SEL_OUT		2

include/scsi/scsi_tcq.h

@@ -97,13 +97,9 @@ static inline void scsi_deactivate_tcq(struct scsi_device *sdev, int depth)
 static inline int scsi_populate_tag_msg(struct scsi_cmnd *cmd, char *msg)
 {
         struct request *req = cmd->request;
-	struct scsi_device *sdev = cmd->device;
 
         if (blk_rq_tagged(req)) {
-		if (sdev->ordered_tags && req->cmd_flags & REQ_HARDBARRIER)
-        	        *msg++ = MSG_ORDERED_TAG;
-        	else
-        	        *msg++ = MSG_SIMPLE_TAG;
+		*msg++ = MSG_SIMPLE_TAG;
         	*msg++ = req->tag;
         	return 2;
 	}

mm/swapfile.c

@@ -139,7 +139,7 @@ static int discard_swap(struct swap_info_struct *si)
 	nr_blocks = ((sector_t)se->nr_pages - 1) << (PAGE_SHIFT - 9);
 	if (nr_blocks) {
 		err = blkdev_issue_discard(si->bdev, start_block,
-				nr_blocks, GFP_KERNEL, BLKDEV_IFL_WAIT);
+				nr_blocks, GFP_KERNEL, 0);
 		if (err)
 			return err;
 		cond_resched();
@@ -150,7 +150,7 @@ static int discard_swap(struct swap_info_struct *si)
 		nr_blocks = (sector_t)se->nr_pages << (PAGE_SHIFT - 9);
 
 		err = blkdev_issue_discard(si->bdev, start_block,
-				nr_blocks, GFP_KERNEL, BLKDEV_IFL_WAIT);
+				nr_blocks, GFP_KERNEL, 0);
 		if (err)
 			break;
 
@@ -189,7 +189,7 @@ static void discard_swap_cluster(struct swap_info_struct *si,
 			start_block <<= PAGE_SHIFT - 9;
 			nr_blocks <<= PAGE_SHIFT - 9;
 			if (blkdev_issue_discard(si->bdev, start_block,
-				    nr_blocks, GFP_NOIO, BLKDEV_IFL_WAIT))
+				    nr_blocks, GFP_NOIO, 0))
 				break;
 		}