linux-toradex.git/include/linux/blkdev.h, branch v3.14-rc2

kernel: use lockless list for smp_call_function_single

2014-01-31T00:56:54+00:00

Make smp_call_function_single and friends more efficient by using a
lockless list.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Jan Kara 
Cc: Jens Axboe 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

bcache/md: Use raid stripe size

2014-01-08T21:05:09+00:00

Now that we've got code for raid5/6 stripe awareness, bcache just needs
to know about the stripes and when writing partial stripes is expensive
- we probably don't want to enable this optimization for raid1 or 10,
even though they have stripes. So add a flag to queue_limits.

Signed-off-by: Kent Overstreet

block: Immutable bio vecs

2013-11-24T06:33:49+00:00

This adds a mechanism by which we can advance a bio by an arbitrary
number of bytes without modifying the biovec: bio->bi_iter.bi_bvec_done
indicates the number of bytes completed in the current bvec.

Various driver code still needs to be updated to not refer to the bvec
directly before we can use this for interesting things, like efficient
bio splitting.

Signed-off-by: Kent Overstreet 
Cc: Jens Axboe 
Cc: Lars Ellenberg 
Cc: Paul Clements 
Cc: drbd-user@lists.linbit.com
Cc: nbd-general@lists.sourceforge.net

block: Convert bio_for_each_segment() to bvec_iter

2013-11-24T06:33:49+00:00

More prep work for immutable biovecs - with immutable bvecs drivers
won't be able to use the biovec directly, they'll need to use helpers
that take into account bio->bi_iter.bi_bvec_done.

This updates callers for the new usage without changing the
implementation yet.

Signed-off-by: Kent Overstreet 
Cc: Jens Axboe 
Cc: Geert Uytterhoeven 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: "Ed L. Cashin" 
Cc: Nick Piggin 
Cc: Lars Ellenberg 
Cc: Jiri Kosina 
Cc: Paul Clements 
Cc: Jim Paris 
Cc: Geoff Levand 
Cc: Yehuda Sadeh 
Cc: Sage Weil 
Cc: Alex Elder 
Cc: ceph-devel@vger.kernel.org
Cc: Joshua Morris 
Cc: Philip Kelleher 
Cc: Konrad Rzeszutek Wilk 
Cc: Jeremy Fitzhardinge 
Cc: Neil Brown 
Cc: Martin Schwidefsky 
Cc: Heiko Carstens 
Cc: linux390@de.ibm.com
Cc: Nagalakshmi Nandigama 
Cc: Sreekanth Reddy 
Cc: support@lsi.com
Cc: "James E.J. Bottomley" 
Cc: Greg Kroah-Hartman 
Cc: Alexander Viro 
Cc: Steven Whitehouse 
Cc: Herton Ronaldo Krzesinski 
Cc: Tejun Heo 
Cc: Andrew Morton 
Cc: Guo Chao 
Cc: Asai Thambi S P 
Cc: Selvan Mani 
Cc: Sam Bradshaw 
Cc: Matthew Wilcox 
Cc: Keith Busch 
Cc: Stephen Hemminger 
Cc: Quoc-Son Anh 
Cc: Sebastian Ott 
Cc: Nitin Gupta 
Cc: Minchan Kim 
Cc: Jerome Marchand 
Cc: Seth Jennings 
Cc: "Martin K. Petersen" 
Cc: Mike Snitzer 
Cc: Vivek Goyal 
Cc: "Darrick J. Wong" 
Cc: Chris Metcalf 
Cc: Jan Kara 
Cc: linux-m68k@lists.linux-m68k.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: drbd-user@lists.linbit.com
Cc: nbd-general@lists.sourceforge.net
Cc: cbe-oss-dev@lists.ozlabs.org
Cc: xen-devel@lists.xensource.com
Cc: virtualization@lists.linux-foundation.org
Cc: linux-raid@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Cc: DL-MPTFusionLinux@lsi.com
Cc: linux-scsi@vger.kernel.org
Cc: devel@driverdev.osuosl.org
Cc: linux-fsdevel@vger.kernel.org
Cc: cluster-devel@redhat.com
Cc: linux-mm@kvack.org
Acked-by: Geoff Levand

blk-mq: ensure that we set REQ_IO_STAT so diskstats work

2013-11-19T16:25:07+00:00

If disk stats are enabled on the queue, a request needs to
be marked with REQ_IO_STAT for accounting to be active on
that request. This fixes an issue with virtio-blk not
showing up in /proc/diskstats after the conversion to
blk-mq.

Add QUEUE_FLAG_MQ_DEFAULT, setting stats and same cpu-group
completion on by default.

Reported-by: Dave Chinner 
Signed-off-by: Jens Axboe

blk-mq: new multi-queue block IO queueing mechanism

2013-10-25T10:56:00+00:00

Linux currently has two models for block devices:

- The classic request_fn based approach, where drivers use struct
  request units for IO. The block layer provides various helper
  functionalities to let drivers share code, things like tag
  management, timeout handling, queueing, etc.

- The "stacked" approach, where a driver squeezes in between the
  block layer and IO submitter. Since this bypasses the IO stack,
  driver generally have to manage everything themselves.

With drivers being written for new high IOPS devices, the classic
request_fn based driver doesn't work well enough. The design dates
back to when both SMP and high IOPS was rare. It has problems with
scaling to bigger machines, and runs into scaling issues even on
smaller machines when you have IOPS in the hundreds of thousands
per device.

The stacked approach is then most often selected as the model
for the driver. But this means that everybody has to re-invent
everything, and along with that we get all the problems again
that the shared approach solved.

This commit introduces blk-mq, block multi queue support. The
design is centered around per-cpu queues for queueing IO, which
then funnel down into x number of hardware submission queues.
We might have a 1:1 mapping between the two, or it might be
an N:M mapping. That all depends on what the hardware supports.

blk-mq provides various helper functions, which include:

- Scalable support for request tagging. Most devices need to
  be able to uniquely identify a request both in the driver and
  to the hardware. The tagging uses per-cpu caches for freed
  tags, to enable cache hot reuse.

- Timeout handling without tracking request on a per-device
  basis. Basically the driver should be able to get a notification,
  if a request happens to fail.

- Optional support for non 1:1 mappings between issue and
  submission queues. blk-mq can redirect IO completions to the
  desired location.

- Support for per-request payloads. Drivers almost always need
  to associate a request structure with some driver private
  command structure. Drivers can tell blk-mq this at init time,
  and then any request handed to the driver will have the
  required size of memory associated with it.

- Support for merging of IO, and plugging. The stacked model
  gets neither of these. Even for high IOPS devices, merging
  sequential IO reduces per-command overhead and thus
  increases bandwidth.

For now, this is provided as a potential 3rd queueing model, with
the hope being that, as it matures, it can replace both the classic
and stacked model. That would get us back to having just 1 real
model for block devices, leaving the stacked approach to dm/md
devices (as it was originally intended).

Contributions in this patch from the following people:

Shaohua Li 
Alexander Gordeev 
Christoph Hellwig 
Mike Christie 
Matias Bjorling 
Jeff Moyer 

Acked-by: Christoph Hellwig 
Signed-off-by: Jens Axboe

block: remove request ref_count

2013-10-25T10:55:59+00:00

This reference count has been around since before git history, but the only
place where it's used is in blk_execute_rq, and ther it is entirely useless
as it is incremented before submitting the request and decremented in the
end_io handler before waking up the submitter thread.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Jens Axboe

block: make rq->cmd_flags be 64-bit

2013-10-25T10:55:59+00:00

We have officially run out of flags in a 32-bit space. Extend it
to 64-bit even on 32-bit archs.

Reviewed-by: Christoph Hellwig 
Signed-off-by: Jens Axboe

block: Add nr_bios to block_rq_remap tracepoint

2013-09-21T19:57:47+00:00

Adding the number of bios in a remapped request to 'block_rq_remap'
tracepoint.

Request remapper clones bios in a request to track the completion
status of each bio. So the number of bios can be useful information
for investigation.

Related discussions:
  http://www.redhat.com/archives/dm-devel/2013-August/msg00084.html
  http://www.redhat.com/archives/dm-devel/2013-September/msg00024.html

Signed-off-by: Jun'ichi Nomura 
Acked-by: Mike Snitzer 
Cc: Jens Axboe 
Signed-off-by: Jens Axboe

Merge branch 'for-3.10/core' of git://git.kernel.dk/linux-block

2013-05-08T17:13:35+00:00

Pull block core updates from Jens Axboe:

 - Major bit is Kents prep work for immutable bio vecs.

 - Stable candidate fix for a scheduling-while-atomic in the queue
   bypass operation.

 - Fix for the hang on exceeded rq->datalen 32-bit unsigned when merging
   discard bios.

 - Tejuns changes to convert the writeback thread pool to the generic
   workqueue mechanism.

 - Runtime PM framework, SCSI patches exists on top of these in James'
   tree.

 - A few random fixes.

* 'for-3.10/core' of git://git.kernel.dk/linux-block: (40 commits)
  relay: move remove_buf_file inside relay_close_buf
  partitions/efi.c: replace useless kzalloc's by kmalloc's
  fs/block_dev.c: fix iov_shorten() criteria in blkdev_aio_read()
  block: fix max discard sectors limit
  blkcg: fix "scheduling while atomic" in blk_queue_bypass_start
  Documentation: cfq-iosched: update documentation help for cfq tunables
  writeback: expose the bdi_wq workqueue
  writeback: replace custom worker pool implementation with unbound workqueue
  writeback: remove unused bdi_pending_list
  aoe: Fix unitialized var usage
  bio-integrity: Add explicit field for owner of bip_buf
  block: Add an explicit bio flag for bios that own their bvec
  block: Add bio_alloc_pages()
  block: Convert some code to bio_for_each_segment_all()
  block: Add bio_for_each_segment_all()
  bounce: Refactor __blk_queue_bounce to not use bi_io_vec
  raid1: use bio_copy_data()
  pktcdvd: Use bio_reset() in disabled code to kill bi_idx usage
  pktcdvd: use bio_copy_data()
  block: Add bio_copy_data()
  ...