linux/block
Tejun Heo 4fed947cb3 block: implement REQ_FLUSH/FUA based interface for FLUSH/FUA requests
Now that the backend conversion is complete, export sequenced
FLUSH/FUA capability through REQ_FLUSH/FUA flags.  REQ_FLUSH means the
device cache should be flushed before executing the request.  REQ_FUA
means that the data in the request should be on non-volatile media on
completion.

Block layer will choose the correct way of implementing the semantics
and execute it.  The request may be passed to the device directly if
the device can handle it; otherwise, it will be sequenced using one or
more proxy requests.  Devices will never see REQ_FLUSH and/or FUA
which it doesn't support.

Also, unlike the original REQ_HARDBARRIER, REQ_FLUSH/FUA requests are
never failed with -EOPNOTSUPP.  If the underlying device doesn't
support FLUSH/FUA, the block layer simply make those noop.  IOW, it no
longer distinguishes between writeback cache which doesn't support
cache flush and writethrough/no cache.  Devices which have WB cache
w/o flush are very difficult to come by these days and there's nothing
much we can do anyway, so it doesn't make sense to require everyone to
implement -EOPNOTSUPP handling.  This will simplify filesystems and
block drivers as they can drop -EOPNOTSUPP retry logic for barriers.

* QUEUE_ORDERED_* are removed and QUEUE_FSEQ_* are moved into
  blk-flush.c.

* REQ_FLUSH w/o data can also be directly passed to drivers without
  sequencing but some drivers assume that zero length requests don't
  have rq->bio which isn't true for these requests requiring the use
  of proxy requests.

* REQ_COMMON_MASK now includes REQ_FLUSH | REQ_FUA so that they are
  copied from bio to request.

* WRITE_BARRIER is marked deprecated and WRITE_FLUSH, WRITE_FUA and
  WRITE_FLUSH_FUA are added.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-09-10 12:35:37 +02:00
..
blk-cgroup.c Merge branch 'master' into for-2.6.35 2010-05-21 21:27:26 +02:00
blk-cgroup.h blk-cgroup: config options re-arrangement 2010-04-26 19:27:56 +02:00
blk-core.c block: implement REQ_FLUSH/FUA based interface for FLUSH/FUA requests 2010-09-10 12:35:37 +02:00
blk-exec.c block: remove wrappers for request type/flags 2010-08-07 18:17:56 +02:00
blk-flush.c block: implement REQ_FLUSH/FUA based interface for FLUSH/FUA requests 2010-09-10 12:35:37 +02:00
blk-integrity.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
blk-ioc.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
blk-iopoll.c tree-wide: fix assorted typos all over the place 2009-12-04 15:39:55 +01:00
blk-lib.c block: add secure discard 2010-08-12 08:43:30 -07:00
blk-map.c block: unify flags for struct bio and struct request 2010-08-07 18:20:39 +02:00
blk-merge.c gcc-4.6: block: fix unused but set variables in blk-merge 2010-08-07 18:23:10 +02:00
blk-settings.c block: deprecate barrier and replace blk_queue_ordered() with blk_queue_flush() 2010-09-10 12:35:36 +02:00
blk-softirq.c generic-ipi: remove CSD_FLAG_WAIT 2009-02-25 14:13:44 +01:00
blk-sysfs.c block: add helpers for the trivial queue flag sysfs show/store entries 2010-08-07 18:13:50 +02:00
blk-tag.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
blk-timeout.c block: ensure jiffies wrap is handled correctly in blk_rq_timed_out_timer 2010-04-21 17:42:08 +02:00
blk.h block: implement REQ_FLUSH/FUA based interface for FLUSH/FUA requests 2010-09-10 12:35:37 +02:00
bsg.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
cfq-iosched.c block: unify flags for struct bio and struct request 2010-08-07 18:20:39 +02:00
cfq.h cfq: fix recursive call in cfq_blkiocg_update_completion_stats() 2010-06-21 09:10:55 +02:00
compat_ioctl.c block: add secure discard 2010-08-12 08:43:30 -07:00
deadline-iosched.c block: convert to pos and nr_sectors accessors 2009-05-11 09:50:54 +02:00
elevator.c block: drop barrier ordering by queue draining 2010-09-10 12:35:36 +02:00
genhd.c block: remove all rcu head initializations 2010-05-21 20:01:02 +02:00
ioctl.c block: add secure discard 2010-08-12 08:43:30 -07:00
Kconfig blk-cgroup: config options re-arrangement 2010-04-26 19:27:56 +02:00
Kconfig.iosched blk-cgroup: config options re-arrangement 2010-04-26 19:27:56 +02:00
Makefile block: rename blk-barrier.c to blk-flush.c 2010-09-10 12:35:36 +02:00
noop-iosched.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
scsi_ioctl.c block/scsi_ioctl.c: quiet sparse noise 2009-11-04 09:10:33 +01:00