AcoSail/kernel_optimize_test
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fa1bf42ff9
kernel_optimize_test/block
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Jeff Moyer fa1bf42ff9 allow blk_flush_policy to return REQ_FSEQ_DATA independent of *FLUSH 
blk_insert_flush has the following check:

	/*
	 * If there's data but flush is not necessary, the request can be
	 * processed directly without going through flush machinery.  Queue
	 * for normal execution.
	 */
	if ((policy & REQ_FSEQ_DATA) &&
	    !(policy & (REQ_FSEQ_PREFLUSH | REQ_FSEQ_POSTFLUSH))) {
		list_add_tail(&rq->queuelist, &q->queue_head);
		return;
	}

However, blk_flush_policy will not return with policy set to only
REQ_FSEQ_DATA:

static unsigned int blk_flush_policy(unsigned int fflags, struct request *rq)
{
	unsigned int policy = 0;

	if (fflags & REQ_FLUSH) {
		if (rq->cmd_flags & REQ_FLUSH)
			policy |= REQ_FSEQ_PREFLUSH;
		if (blk_rq_sectors(rq))
			policy |= REQ_FSEQ_DATA;
		if (!(fflags & REQ_FUA) && (rq->cmd_flags & REQ_FUA))
			policy |= REQ_FSEQ_POSTFLUSH;
	}
	return policy;
}

Notice that REQ_FSEQ_DATA is only set if REQ_FLUSH is set.  Fix this
mismatch by moving the setting of REQ_FSEQ_DATA outside of the REQ_FLUSH
check.

Tejun notes:

  Hmmm... yes, this can become a correctness issue if (and only if)
  blk_queue_flush() is called to change q->flush_flags while requests
  are in-flight; otherwise, requests wouldn't reach the function at all.
  Also, I think it would be a generally good idea to always set
  FSEQ_DATA if the request has data.

Cheers,
Jeff

Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2011-08-09 20:32:09 +02:00
..
blk-cgroup.c cgroups: add per-thread subsystem callbacks 2011-05-26 17:12:34 -07:00
blk-cgroup.h cfq-iosched: Make IO merge related stats per cpu 2011-05-23 10:02:19 +02:00
blk-core.c fail_make_request: cleanup should_fail_request 2011-07-26 16:49:46 -07:00
blk-exec.c [SCSI] fix crash in scsi_dispatch_cmd() 2011-07-21 14:21:18 -07:00
blk-flush.c allow blk_flush_policy to return REQ_FSEQ_DATA independent of *FLUSH 2011-08-09 20:32:09 +02:00
blk-integrity.c
blk-ioc.c Merge branch 'for-linus' into for-3.1/core 2011-07-01 16:17:13 +02:00
blk-iopoll.c
blk-lib.c block: fix patch import error in max_discard_sectors check 2011-07-23 20:34:59 +02:00
blk-map.c
blk-merge.c
blk-settings.c block: Fix discard topology stacking and reporting 2011-05-18 10:37:35 +02:00
blk-softirq.c block: Make rq_affinity = 1 work as expected 2011-08-05 09:37:47 +02:00
blk-sysfs.c block: strict rq_affinity 2011-07-23 20:44:25 +02:00
blk-tag.c
blk-throttle.c blk-throttle: correctly determine sync bio 2011-08-01 10:31:06 +02:00
blk-timeout.c
blk.h Merge branch 'for-linus' into for-2.6.40/core 2011-05-20 20:36:16 +02:00
bsg-lib.c bsg-lib: add module.h include 2011-08-02 10:43:35 +02:00
bsg.c bsg: fix address space warning from sparse 2011-06-20 13:27:45 +02:00
cfq-iosched.c cfq-iosched: Reduce linked group count upon group destruction 2011-08-02 09:24:09 +02:00
cfq.h
compat_ioctl.c compat_ioctl: fix warning caused by qemu 2011-07-01 22:32:26 +02:00
deadline-iosched.c iosched: prevent aliased requests from starving other I/O 2011-06-02 21:19:05 +02:00
elevator.c iosched: prevent aliased requests from starving other I/O 2011-06-02 21:19:05 +02:00
genhd.c block/genhd.c: remove useless cast in diskstats_show() 2011-08-02 12:43:50 +02:00
ioctl.c
Kconfig block: add bsg helper library 2011-07-31 22:05:09 +02:00
Kconfig.iosched
Makefile block: add bsg helper library 2011-07-31 22:05:09 +02:00
noop-iosched.c
scsi_ioctl.c