__smp_call_function_single already avoids multiple IPIs by internally
queing up the items, and now also is available for non-SMP builds as
a trivially correct stub, so there is no need to wrap it.  If the
additional lock roundtrip cause problems my patch to convert the
generic IPI code to llists is waiting to get merged will fix it.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

blk_rq_init() is called in req's complete handler to initialize
the request, so the members of start_time and start_time_ns might
become inaccurate when it is allocated in future.

The patch initializes the two members in blk_mq_rq_ctx_init() to
fix the problem.
Signed-off-by: NMing Lei <tom.leiming@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

blk_mq_free_queue() is called from release handler of
queue kobject, so it needn't be called from drivers.

Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: NMing Lei <tom.leiming@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This patch moves synchronization on mq->delay_work
from blk_mq_free_queue() to blk_sync_queue(), so that
blk_sync_queue can work on mq.

Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: NMing Lei <tom.leiming@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

blk_mq_drain_queue() is introduced so that we can drain
mq queue inside blk_cleanup_queue().

Also don't accept new requests any more if queue is marked
as dying.

Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: NMing Lei <tom.leiming@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

All objects, which are allocated in blk_mq_register_disk, must be
released in blk_mq_unregister_disk.

I use a KVM virtual machine and virtio disk to reproduce this issue.

kmemleak: 18 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
$ cat /sys/kernel/debug/kmemleak | head -n 30
unreferenced object 0xffff8800b6636150 (size 8):
  comm "kworker/0:2", pid 65, jiffies 4294809903 (age 86.358s)
  hex dump (first 8 bytes):
    76 69 72 74 69 6f 34 00                          virtio4.
  backtrace:
    [<ffffffff8165d41e>] kmemleak_alloc+0x4e/0xb0
    [<ffffffff8118cfc5>] __kmalloc_track_caller+0xf5/0x260
    [<ffffffff81155b11>] kstrdup+0x31/0x60
    [<ffffffff812242be>] sysfs_new_dirent+0x2e/0x140
    [<ffffffff81224678>] create_dir+0x38/0xe0
    [<ffffffff812249e3>] sysfs_create_dir_ns+0x73/0xc0
    [<ffffffff8130dfa9>] kobject_add_internal+0xc9/0x340
    [<ffffffff8130e535>] kobject_add+0x65/0xb0
    [<ffffffff813f34f8>] device_add+0x128/0x660
    [<ffffffff813f3a4a>] device_register+0x1a/0x20
    [<ffffffff813ae6f8>] register_virtio_device+0x98/0xe0
    [<ffffffff813b0cce>] virtio_pci_probe+0x12e/0x1c0
    [<ffffffff81340675>] local_pci_probe+0x45/0xa0
    [<ffffffff81341a51>] pci_device_probe+0x121/0x130
    [<ffffffff813f67f7>] driver_probe_device+0x87/0x390
    [<ffffffff813f6b3b>] __device_attach+0x3b/0x40
unreferenced object 0xffff8800b65aa1d8 (size 144):

Fixes: 320ae51f (blk-mq: new multi-queue block IO queueing mechanism)
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: NAndrey Vagin <avagin@openvz.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

If accounting is on, we will do the IO completion accounting after
we have freed the request. Fix that by moving it sooner instead.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

The uninitialized_var() macro appears to not work on structs...
Get rid of it, and manually initialize instead.
Signed-off-by: NKent Overstreet <kmo@daterainc.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

If __GFP_WAIT isn't set and we fail allocating, when we go
to drop the reference on the ctx, we will attempt to dereference
the NULL rq. Fix that.
Signed-off-by: NJeff Moyer <jmoyer@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Signed-off-by: NKent Overstreet <kmo@daterainc.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

It was being open coded in a few places.
Signed-off-by: NKent Overstreet <kmo@daterainc.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joern Engel <joern@logfs.org>
Cc: Prasad Joshi <prasadjoshi.linux@gmail.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Chris Mason <chris.mason@fusionio.com>
Acked-by: NNeilBrown <neilb@suse.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

bio_iovec_idx() and __bio_iovec() don't have any valid uses anymore -
previous users have been converted to bio_iovec_iter() or other methods.

__BVEC_END() has to go too - the bvec array can't be used directly for
the last biovec because we might only be using the first portion of it,
we have to iterate over the bvec array with bio_for_each_segment() which
checks against the current value of bi_iter.bi_size.
Signed-off-by: NKent Overstreet <kmo@daterainc.com>
Cc: Jens Axboe <axboe@kernel.dk>

The bio integrity is also stored in a bvec array, so if we use the bvec
iter code we just added, the integrity code won't need to implement its
own iteration stuff (bio_integrity_mark_head(), bio_integrity_mark_tail())
Signed-off-by: NKent Overstreet <kmo@daterainc.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: "James E.J. Bottomley" <JBottomley@parallels.com>

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: NKent Overstreet <kmo@daterainc.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: "Ed L. Cashin" <ecashin@coraid.com>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Lars Ellenberg <drbd-dev@lists.linbit.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Paul Clements <Paul.Clements@steeleye.com>
Cc: Jim Paris <jim@jtan.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Yehuda Sadeh <yehuda@inktank.com>
Cc: Sage Weil <sage@inktank.com>
Cc: Alex Elder <elder@inktank.com>
Cc: ceph-devel@vger.kernel.org
Cc: Joshua Morris <josh.h.morris@us.ibm.com>
Cc: Philip Kelleher <pjk1939@linux.vnet.ibm.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Neil Brown <neilb@suse.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux390@de.ibm.com
Cc: Nagalakshmi Nandigama <Nagalakshmi.Nandigama@lsi.com>
Cc: Sreekanth Reddy <Sreekanth.Reddy@lsi.com>
Cc: support@lsi.com
Cc: "James E.J. Bottomley" <JBottomley@parallels.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Guo Chao <yan@linux.vnet.ibm.com>
Cc: Asai Thambi S P <asamymuthupa@micron.com>
Cc: Selvan Mani <smani@micron.com>
Cc: Sam Bradshaw <sbradshaw@micron.com>
Cc: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Stephen Hemminger <shemminger@vyatta.com>
Cc: Quoc-Son Anh <quoc-sonx.anh@intel.com>
Cc: Sebastian Ott <sebott@linux.vnet.ibm.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Jan Kara <jack@suse.cz>
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: NGeoff Levand <geoff@infradead.org>

Immutable biovecs are going to require an explicit iterator. To
implement immutable bvecs, a later patch is going to add a bi_bvec_done
member to this struct; for now, this patch effectively just renames
things.
Signed-off-by: NKent Overstreet <kmo@daterainc.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: "Ed L. Cashin" <ecashin@coraid.com>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Lars Ellenberg <drbd-dev@lists.linbit.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Yehuda Sadeh <yehuda@inktank.com>
Cc: Sage Weil <sage@inktank.com>
Cc: Alex Elder <elder@inktank.com>
Cc: ceph-devel@vger.kernel.org
Cc: Joshua Morris <josh.h.morris@us.ibm.com>
Cc: Philip Kelleher <pjk1939@linux.vnet.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Neil Brown <neilb@suse.de>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: dm-devel@redhat.com
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux390@de.ibm.com
Cc: Boaz Harrosh <bharrosh@panasas.com>
Cc: Benny Halevy <bhalevy@tonian.com>
Cc: "James E.J. Bottomley" <JBottomley@parallels.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Nicholas A. Bellinger" <nab@linux-iscsi.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Chris Mason <chris.mason@fusionio.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Dave Kleikamp <shaggy@kernel.org>
Cc: Joern Engel <joern@logfs.org>
Cc: Prasad Joshi <prasadjoshi.linux@gmail.com>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: KONISHI Ryusuke <konishi.ryusuke@lab.ntt.co.jp>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Ben Myers <bpm@sgi.com>
Cc: xfs@oss.sgi.com
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Guo Chao <yan@linux.vnet.ibm.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Asai Thambi S P <asamymuthupa@micron.com>
Cc: Selvan Mani <smani@micron.com>
Cc: Sam Bradshaw <sbradshaw@micron.com>
Cc: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Cc: "Roger Pau Monné" <roger.pau@citrix.com>
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com>
Cc: Sebastian Ott <sebott@linux.vnet.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Jiang Liu <jiang.liu@huawei.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Jerome Marchand <jmarchand@redhat.com>
Cc: Joe Perches <joe@perches.com>
Cc: Peng Tao <tao.peng@emc.com>
Cc: Andy Adamson <andros@netapp.com>
Cc: fanchaoting <fanchaoting@cn.fujitsu.com>
Cc: Jie Liu <jeff.liu@oracle.com>
Cc: Sunil Mushran <sunil.mushran@gmail.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Namjae Jeon <namjae.jeon@samsung.com>
Cc: Pankaj Kumar <pankaj.km@samsung.com>
Cc: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: Mel Gorman <mgorman@suse.de>6

It was being open coded in a few places.
Signed-off-by: NKent Overstreet <kmo@daterainc.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joern Engel <joern@logfs.org>
Cc: Prasad Joshi <prasadjoshi.linux@gmail.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Chris Mason <chris.mason@fusionio.com>
Acked-by: NNeilBrown <neilb@suse.de>

Use ARRAY_SIZE instead of sizeof to get proper max for label length.

Since this is just a read out of bounds it's not that bad, but the
problem becomes user-visible eg if one tries to use DEBUG_PAGEALLOC and
DEBUG_RODATA, at least with some enhancements from Hiroshi.  Of course
the destination array can contain garbage when we read beyond the end of
source array so that would be another user-visible problem.
Signed-off-by: NAntti P Miettinen <amiettinen@nvidia.com>
Reviewed-by: NHiroshi Doyu <hdoyu@nvidia.com>
Tested-by: NHiroshi Doyu <hdoyu@nvidia.com>
Cc: Will Drewry <wad@chromium.org>
Cc: Matt Fleming <matt.fleming@intel.com>
Acked-by: NDavidlohr Bueso <davidlohr@hp.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

While u64_stats_fetch_retry is only preempt_disable on 32bit
UP system. This is not enough to avoid preemption by bh and
may read strange 64 bit value.
Signed-off-by: NHong Zhiguo <zhiguohong@tencent.com>
Acked-by: NTejun Heo <tj@kernel.org>
Cc: stable@kernel.org
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We need it to make 'btt' from blktrace happy, otherwise
we are missing one state transition.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

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: NDave Chinner <david@fromorbit.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We've switched over every architecture that supports SMP to it, so
remove the new useless config variable.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Cc: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The new blk-mq code added new instances of __cpuinit usage.
We removed this a couple versions ago; we now want to remove
the compat no-op stubs.  Introducing new users is not what
we want to see at this point in time, as it will break once
the stubs are gone.
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Now that seqcounts are lockdep enabled objects, we need to explicitly
initialize runtime allocated seqcounts so that lockdep can track them.

Without this patch, Fengguang was seeing:

  [    4.127282] INFO: trying to register non-static key.
  [    4.128027] the code is fine but needs lockdep annotation.
  [    4.128027] turning off the locking correctness validator.
  [    4.128027] CPU: 0 PID: 96 Comm: kworker/u4:1 Not tainted 3.12.0-next-20131108-10601-gbad570d #2
  [    4.128027] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
  [    ...     ]
  [    4.128027] Call Trace:
  [    4.128027]  [<7908e744>] ? console_unlock+0x353/0x380
  [    4.128027]  [<79dc7cf2>] dump_stack+0x48/0x60
  [    4.128027]  [<7908953e>] __lock_acquire.isra.26+0x7e3/0xceb
  [    4.128027]  [<7908a1c5>] lock_acquire+0x71/0x9a
  [    4.128027]  [<794079aa>] ? blk_throtl_bio+0x1c3/0x485
  [    4.128027]  [<7940658b>] throtl_update_dispatch_stats+0x7c/0x153
  [    4.128027]  [<794079aa>] ? blk_throtl_bio+0x1c3/0x485
  [    4.128027]  [<794079aa>] blk_throtl_bio+0x1c3/0x485
  ...

Use u64_stats_init() for all affected data structures, which initializes
the seqcount.
Reported-and-Tested-by: NFengguang Wu <fengguang.wu@intel.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
[ Folded in another fix from the mailing list as well as a fix to that fix. Tweaked commit message. ]
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1384314134-6895-1-git-send-email-john.stultz@linaro.org
[ So I actually think that the two SOBs from PeterZ are the right depiction of the patch route. ]
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: NGrygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: NSantosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This patch fixes coccinelle error regarding usage of IS_ERR and
PTR_ERR instead of PTR_ERR_OR_ZERO.
Signed-off-by: NDuan Jiong <duanj.fnst@cn.fujitsu.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This patch fixes coccinelle error regarding usage of IS_ERR and
PTR_ERR instead of PTR_ERR_OR_ZERO.
Signed-off-by: NDuan Jiong <duanj.fnst@cn.fujitsu.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

do_div() (called by sector_div() if CONFIG_LBDAF=y) is meant for divisions
of 64-bit number by 32-bit numbers.  Passing 64-bit divisor types caused
issues in the past on 32-bit platforms, cfr. commit
ea077b1b ("m68k: Truncate base in
do_div()").

As queue_limits.max_discard_sectors and .discard_granularity are unsigned
int, max_discard_sectors and granularity should be unsigned int.
As bdev_discard_alignment() returns int, alignment should be int.
Now 2 calls to sector_div() can be replaced by 32-bit arithmetic:
  - The 64-bit modulo operation can become a 32-bit modulo operation,
  - The 64-bit division and multiplication can be replaced by a 32-bit
    modulo operation and a subtraction.
Signed-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

No need for silly open coding - and struct sg_iovec has exactly the same
layout as struct iovec...
Signed-off-by: NKent Overstreet <kmo@daterainc.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This patch enables the sysfs to control I/O request merge
functionality in the plug list. While this control has been
implemented for the request queue, it was dismissed in the plug list.
Therefore, block layer merges requests together (or attempt to merge)
even if the merge capability was disable using sysfs nomerge parameter
value 2.

This limitation is directly affects functionality of io_submit()
system call. The system call enables user to submit a bunch of IO
requests from user space using struct iocb **ios input argument.
However, the unconditioned merging functionality in the plug list
potentially merges these requests together down the road. Therefore,
there is no way to distinguish between an application sending bunch of
sequential IOs and an application sending one big IO. Ultimately, all
requests generated by the former app merge within the plug list
together and looks similar to the second app.

While the merging functionality is a desirable feature to improve the
performance of IO subsystem for some applications, it is not useful
for other application like ours at all.
Signed-off-by: NAlireza Haghdoost <alireza@cs.umn.edu>
Reviewed-by: NJeff Moyer <jmoyer@redhat.com>

Coding style modified.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Without this patch all DM devices will default to BLK_MAX_SEGMENT_SIZE
(65536) even if the underlying device(s) have a larger value -- this is
due to blk_stack_limits() using min_not_zero() when stacking the
max_segment_size limit.

1073741824

before patch:
65536

after patch:
1073741824
Reported-by: NLukasz Flis <l.flis@cyfronet.pl>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org # v3.3+
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Add locking of q->sysfs_lock into elevator_change() (an exported function)
to ensure it is held to protect q->elevator from elevator_init(), even if
elevator_change() is called from non-sysfs paths.
sysfs path (elv_iosched_store) uses __elevator_change(), non-locking
version, as the lock is already taken by elv_iosched_store().
Signed-off-by: NTomoki Sekiyama <tomoki.sekiyama@hds.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

The soft lockup below happens at the boot time of the system using dm
multipath and the udev rules to switch scheduler.

[  356.127001] BUG: soft lockup - CPU#3 stuck for 22s! [sh:483]
[  356.127001] RIP: 0010:[<ffffffff81072a7d>]  [<ffffffff81072a7d>] lock_timer_base.isra.35+0x1d/0x50
...
[  356.127001] Call Trace:
[  356.127001]  [<ffffffff81073810>] try_to_del_timer_sync+0x20/0x70
[  356.127001]  [<ffffffff8118b08a>] ? kmem_cache_alloc_node_trace+0x20a/0x230
[  356.127001]  [<ffffffff810738b2>] del_timer_sync+0x52/0x60
[  356.127001]  [<ffffffff812ece22>] cfq_exit_queue+0x32/0xf0
[  356.127001]  [<ffffffff812c98df>] elevator_exit+0x2f/0x50
[  356.127001]  [<ffffffff812c9f21>] elevator_change+0xf1/0x1c0
[  356.127001]  [<ffffffff812caa50>] elv_iosched_store+0x20/0x50
[  356.127001]  [<ffffffff812d1d09>] queue_attr_store+0x59/0xb0
[  356.127001]  [<ffffffff812143f6>] sysfs_write_file+0xc6/0x140
[  356.127001]  [<ffffffff811a326d>] vfs_write+0xbd/0x1e0
[  356.127001]  [<ffffffff811a3ca9>] SyS_write+0x49/0xa0
[  356.127001]  [<ffffffff8164e899>] system_call_fastpath+0x16/0x1b

This is caused by a race between md device initialization by multipathd and
shell script to switch the scheduler using sysfs.

 - multipathd:
   SyS_ioctl -> do_vfs_ioctl -> dm_ctl_ioctl -> ctl_ioctl -> table_load
   -> dm_setup_md_queue -> blk_init_allocated_queue -> elevator_init
    q->elevator = elevator_alloc(q, e); // not yet initialized

 - sh -c 'echo deadline > /sys/$DEVPATH/queue/scheduler':
   elevator_switch (in the call trace above)
    struct elevator_queue *old = q->elevator;
    q->elevator = elevator_alloc(q, new_e);
    elevator_exit(old);                 // lockup! (*)

 - multipathd: (cont.)
    err = e->ops.elevator_init_fn(q);   // init fails; q->elevator is modified

(*) When del_timer_sync() is called, lock_timer_base() will loop infinitely
while timer->base == NULL. In this case, as timer will never initialized,
it results in lockup.

This patch introduces acquisition of q->sysfs_lock around elevator_init()
into blk_init_allocated_queue(), to provide mutual exclusion between
initialization of the q->scheduler and switching of the scheduler.

This should fix this bugzilla:
https://bugzilla.redhat.com/show_bug.cgi?id=902012Signed-off-by: NTomoki Sekiyama <tomoki.sekiyama@hds.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

__get_cpu_var() is used for multiple purposes in the kernel source. One of
them is address calculation via the form &__get_cpu_var(x).  This calculates
the address for the instance of the percpu variable of the current processor
based on an offset.

Other use cases are for storing and retrieving data from the current
processors percpu area.  __get_cpu_var() can be used as an lvalue when
writing data or on the right side of an assignment.

__get_cpu_var() is defined as :

#define __get_cpu_var(var) (*this_cpu_ptr(&(var)))

__get_cpu_var() always only does an address determination. However, store
and retrieve operations could use a segment prefix (or global register on
other platforms) to avoid the address calculation.

this_cpu_write() and this_cpu_read() can directly take an offset into a
percpu area and use optimized assembly code to read and write per cpu
variables.

This patch converts __get_cpu_var into either an explicit address
calculation using this_cpu_ptr() or into a use of this_cpu operations that
use the offset.  Thereby address calculations are avoided and less registers
are used when code is generated.

At the end of the patch set all uses of __get_cpu_var have been removed so
the macro is removed too.

The patch set includes passes over all arches as well. Once these operations
are used throughout then specialized macros can be defined in non -x86
arches as well in order to optimize per cpu access by f.e.  using a global
register that may be set to the per cpu base.

Transformations done to __get_cpu_var()

1. Determine the address of the percpu instance of the current processor.

	DEFINE_PER_CPU(int, y);
	int *x = &__get_cpu_var(y);

    Converts to

	int *x = this_cpu_ptr(&y);

2. Same as #1 but this time an array structure is involved.

	DEFINE_PER_CPU(int, y[20]);
	int *x = __get_cpu_var(y);

    Converts to

	int *x = this_cpu_ptr(y);

3. Retrieve the content of the current processors instance of a per cpu
variable.

	DEFINE_PER_CPU(int, y);
	int x = __get_cpu_var(y)

   Converts to

	int x = __this_cpu_read(y);

4. Retrieve the content of a percpu struct

	DEFINE_PER_CPU(struct mystruct, y);
	struct mystruct x = __get_cpu_var(y);

   Converts to

	memcpy(&x, this_cpu_ptr(&y), sizeof(x));

5. Assignment to a per cpu variable

	DEFINE_PER_CPU(int, y)
	__get_cpu_var(y) = x;

   Converts to

	this_cpu_write(y, x);

6. Increment/Decrement etc of a per cpu variable

	DEFINE_PER_CPU(int, y);
	__get_cpu_var(y)++

   Converts to

	this_cpu_inc(y)
Signed-off-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

If blkcg_init_queue fails, blk_alloc_queue_node doesn't call bdi_destroy
to clean up structures allocated by the backing dev.

------------[ cut here ]------------
WARNING: at lib/debugobjects.c:260 debug_print_object+0x85/0xa0()
ODEBUG: free active (active state 0) object type: percpu_counter hint:           (null)
Modules linked in: dm_loop dm_mod ip6table_filter ip6_tables uvesafb cfbcopyarea cfbimgblt cfbfillrect fbcon font bitblit fbcon_rotate fbcon_cw fbcon_ud fbcon_ccw softcursor fb fbdev ipt_MASQUERADE iptable_nat nf_nat_ipv4 msr nf_conntrack_ipv4 nf_defrag_ipv4 xt_state ipt_REJECT xt_tcpudp iptable_filter ip_tables x_tables bridge stp llc tun ipv6 cpufreq_userspace cpufreq_stats cpufreq_powersave cpufreq_ondemand cpufreq_conservative spadfs fuse hid_generic usbhid hid raid0 md_mod dmi_sysfs nf_nat_ftp nf_nat nf_conntrack_ftp nf_conntrack lm85 hwmon_vid snd_usb_audio snd_pcm_oss snd_mixer_oss snd_pcm snd_timer snd_page_alloc snd_hwdep snd_usbmidi_lib snd_rawmidi snd soundcore acpi_cpufreq freq_table mperf sata_svw serverworks kvm_amd ide_core ehci_pci ohci_hcd libata ehci_hcd kvm usbcore tg3 usb_common libphy k10temp pcspkr ptp i2c_piix4 i2c_core evdev microcode hwmon rtc_cmos pps_core e100 skge floppy mii processor button unix
CPU: 0 PID: 2739 Comm: lvchange Tainted: G        W
3.10.15-devel #14
Hardware name: empty empty/S3992-E, BIOS 'V1.06   ' 06/09/2009
 0000000000000009 ffff88023c3c1ae8 ffffffff813c8fd4 ffff88023c3c1b20
 ffffffff810399eb ffff88043d35cd58 ffffffff81651940 ffff88023c3c1bf8
 ffffffff82479d90 0000000000000005 ffff88023c3c1b80 ffffffff81039a67
Call Trace:
 [<ffffffff813c8fd4>] dump_stack+0x19/0x1b
 [<ffffffff810399eb>] warn_slowpath_common+0x6b/0xa0
 [<ffffffff81039a67>] warn_slowpath_fmt+0x47/0x50
 [<ffffffff8122aaaf>] ? debug_check_no_obj_freed+0xcf/0x250
 [<ffffffff81229a15>] debug_print_object+0x85/0xa0
 [<ffffffff8122abe3>] debug_check_no_obj_freed+0x203/0x250
 [<ffffffff8113c4ac>] kmem_cache_free+0x20c/0x3a0
 [<ffffffff811f6709>] blk_alloc_queue_node+0x2a9/0x2c0
 [<ffffffff811f672e>] blk_alloc_queue+0xe/0x10
 [<ffffffffa04c0093>] dm_create+0x1a3/0x530 [dm_mod]
 [<ffffffffa04c6bb0>] ? list_version_get_info+0xe0/0xe0 [dm_mod]
 [<ffffffffa04c6c07>] dev_create+0x57/0x2b0 [dm_mod]
 [<ffffffffa04c6bb0>] ? list_version_get_info+0xe0/0xe0 [dm_mod]
 [<ffffffffa04c6bb0>] ? list_version_get_info+0xe0/0xe0 [dm_mod]
 [<ffffffffa04c6528>] ctl_ioctl+0x268/0x500 [dm_mod]
 [<ffffffff81097662>] ? get_lock_stats+0x22/0x70
 [<ffffffffa04c67ce>] dm_ctl_ioctl+0xe/0x20 [dm_mod]
 [<ffffffff81161aad>] do_vfs_ioctl+0x2ed/0x520
 [<ffffffff8116cfc7>] ? fget_light+0x377/0x4e0
 [<ffffffff81161d2b>] SyS_ioctl+0x4b/0x90
 [<ffffffff813cff16>] system_call_fastpath+0x1a/0x1f
---[ end trace 4b5ff0d55673d986 ]---
------------[ cut here ]------------

This fix should be backported to stable kernels starting with 2.6.37. Note
that in the kernels prior to 3.5 the affected code is different, but the
bug is still there - bdi_init is called and bdi_destroy isn't.
Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Acked-by: NTejun Heo <tj@kernel.org>
Cc: stable@kernel.org	# 2.6.37+
Signed-off-by: NJens Axboe <axboe@kernel.dk>

crocode i2c_i801 i2c_core iTCO_wdt iTCO_vendor_support shpchp ioatdma dca be2net sg ses enclosure ext4 mbcache jbd2 sd_mod crc_t10dif ahci megaraid_sas(U) dm_mirror dm_region_hash dm_log dm_mod [last unloaded: scsi_wait_scan]

Pid: 491, comm: scsi_eh_0 Tainted: G        W  ----------------   2.6.32-220.13.1.el6.x86_64 #1 IBM  -[8722PAX]-/00D1461
RIP: 0010:[<ffffffff8124e424>]  [<ffffffff8124e424>] blk_requeue_request+0x94/0xa0
RSP: 0018:ffff881057eefd60  EFLAGS: 00010012
RAX: ffff881d99e3e8a8 RBX: ffff881d99e3e780 RCX: ffff881d99e3e8a8
RDX: ffff881d99e3e8a8 RSI: ffff881d99e3e780 RDI: ffff881d99e3e780
RBP: ffff881057eefd80 R08: ffff881057eefe90 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff881057f92338
R13: 0000000000000000 R14: ffff881057f92338 R15: ffff883058188000
FS:  0000000000000000(0000) GS:ffff880040200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0018 ES: 0018 CR0: 000000008005003b
CR2: 00000000006d3ec0 CR3: 000000302cd7d000 CR4: 00000000000406b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process scsi_eh_0 (pid: 491, threadinfo ffff881057eee000, task ffff881057e29540)
Stack:
 0000000000001057 0000000000000286 ffff8810275efdc0 ffff881057f16000
<0> ffff881057eefdd0 ffffffff81362323 ffff881057eefe20 ffffffff8135f393
<0> ffff881057e29af8 ffff8810275efdc0 ffff881057eefe78 ffff881057eefe90
Call Trace:
 [<ffffffff81362323>] __scsi_queue_insert+0xa3/0x150
 [<ffffffff8135f393>] ? scsi_eh_ready_devs+0x5e3/0x850
 [<ffffffff81362a23>] scsi_queue_insert+0x13/0x20
 [<ffffffff8135e4d4>] scsi_eh_flush_done_q+0x104/0x160
 [<ffffffff8135fb6b>] scsi_error_handler+0x35b/0x660
 [<ffffffff8135f810>] ? scsi_error_handler+0x0/0x660
 [<ffffffff810908c6>] kthread+0x96/0xa0
 [<ffffffff8100c14a>] child_rip+0xa/0x20
 [<ffffffff81090830>] ? kthread+0x0/0xa0
 [<ffffffff8100c140>] ? child_rip+0x0/0x20
Code: 00 00 eb d1 4c 8b 2d 3c 8f 97 00 4d 85 ed 74 bf 49 8b 45 00 49 83 c5 08 48 89 de 4c 89 e7 ff d0 49 8b 45 00 48 85 c0 75 eb eb a4 <0f> 0b eb fe 0f 1f 84 00 00 00 00 00 55 48 89 e5 0f 1f 44 00 00
RIP  [<ffffffff8124e424>] blk_requeue_request+0x94/0xa0
 RSP <ffff881057eefd60>

The RIP is this line:
        BUG_ON(blk_queued_rq(rq));

After digging through the code, I think there may be a race between the
request completion and the timer handler running.

A timer is started for each request put on the device's queue (see
blk_start_request->blk_add_timer).  If the request does not complete
before the timer expires, the timer handler (blk_rq_timed_out_timer)
will mark the request complete atomically:

static inline int blk_mark_rq_complete(struct request *rq)
{
        return test_and_set_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
}

and then call blk_rq_timed_out.  The latter function will call
scsi_times_out, which will return one of BLK_EH_HANDLED,
BLK_EH_RESET_TIMER or BLK_EH_NOT_HANDLED.  If BLK_EH_RESET_TIMER is
returned, blk_clear_rq_complete is called, and blk_add_timer is again
called to simply wait longer for the request to complete.

Now, if the request happens to complete while this is going on, what
happens?  Given that we know the completion handler will bail if it
finds the REQ_ATOM_COMPLETE bit set, we need to focus on the completion
handler running after that bit is cleared.  So, from the above
paragraph, after the call to blk_clear_rq_complete.  If the completion
sets REQ_ATOM_COMPLETE before the BUG_ON in blk_add_timer, we go boom
there (I haven't seen this in the cores).  Next, if we get the
completion before the call to list_add_tail, then the timer will
eventually fire for an old req, which may either be freed or reallocated
(there is evidence that this might be the case).  Finally, if the
completion comes in *after* the addition to the timeout list, I think
it's harmless.  The request will be removed from the timeout list,
req_atom_complete will be set, and all will be well.

This will only actually explain the coredumps *IF* the request
structure was freed, reallocated *and* queued before the error handler
thread had a chance to process it.  That is possible, but it may make
sense to keep digging for another race.  I think that if this is what
was happening, we would see other instances of this problem showing up
as null pointer or garbage pointer dereferences, for example when the
request structure was not re-used.  It looks like we actually do run
into that situation in other reports.

This patch moves the BUG_ON(test_bit(REQ_ATOM_COMPLETE,
&req->atomic_flags)); from blk_add_timer to the only caller that could
trip over it (blk_start_request).  It then inverts the calls to
blk_clear_rq_complete and blk_add_timer in blk_rq_timed_out to address
the race.  I've boot tested this patch, but nothing more.
Signed-off-by: NJeff Moyer <jmoyer@redhat.com>
Acked-by: NHannes Reinecke <hare@suse.de>
Cc: stable@kernel.org
Signed-off-by: NJens Axboe <axboe@kernel.dk>

The blk_queue_bounce_limit() API parameter 'dma_mask' is actually the
maximum address the device can handle rather than a dma_mask. Rename
it accordingly to avoid it being interpreted as dma_mask.

No functional change.

The idea is to fix the bad assumptions about dma_mask wherever it could
be miss-interpreted.

Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: NSantosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

For blk-mq, if a driver has requested per-request payload data
to carry command structures, they are stuffed into req->special.
For an old style request based driver, req->special is used
for the same purpose but indicates that a per-driver request
structure has been prepared for the request already. So for the
old style driver, we do not merge such requests.

As most/all blk-mq drivers will use the payload feature, and
since we have no problem merging on these, make this check
dependent on whether it's a blk-mq enabled driver or not.
Reported-by: NShaohua Li <shli@fusionio.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We switched to plug mq_list for mq, but some code are still using old list.
Signed-off-by: NShaohua Li <shli@fusionio.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

The flush state machine takes in a struct request, which then is
submitted multiple times to the underling driver.  The old block code
requeses the same request for each of those, so it does not have an
issue with tapping into the request pool.  The new one on the other hand
allocates a new request for each of the actualy steps of the flush
sequence. If have already allocated all of the tags for IO, we will
fail allocating the flush request.

Set aside a reserved request just for flushes.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Add a helper to iterate over all hw queues and stop them.  This is useful
for driver that implement PM suspend functionality.
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Modified to just call blk_mq_stop_hw_queue() by Jens.
Signed-off-by: NJens Axboe <axboe@kernel.dk>