Commit Graph

326 Commits

Author SHA1 Message Date
NeilBrown 74018dc306 blk: pass from_schedule to non-request unplug functions.
This will allow md/raid to know why the unplug was called,
and will be able to act according - if !from_schedule it
is safe to perform tasks which could themselves schedule.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-07-31 09:08:15 +02:00
Shaohua Li 2a7d5559b3 block: stack unplug
MD raid1 prepares to dispatch request in unplug callback. If make_request in
low level queue also uses unplug callback to dispatch request, the low level
queue's unplug callback will not be called. Recheck the callback list helps
this case.

Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-07-31 09:08:15 +02:00
NeilBrown 9cbb175088 blk: centralize non-request unplug handling.
Both md and umem has similar code for getting notified on an
blk_finish_plug event.
Centralize this code in block/ and allow each driver to
provide its distinctive difference.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-07-31 09:08:14 +02:00
Tejun Heo a051661ca6 blkcg: implement per-blkg request allocation
Currently, request_queue has one request_list to allocate requests
from regardless of blkcg of the IO being issued.  When the unified
request pool is used up, cfq proportional IO limits become meaningless
- whoever grabs the next request being freed wins the race regardless
of the configured weights.

This can be easily demonstrated by creating a blkio cgroup w/ very low
weight, put a program which can issue a lot of random direct IOs there
and running a sequential IO from a different cgroup.  As soon as the
request pool is used up, the sequential IO bandwidth crashes.

This patch implements per-blkg request_list.  Each blkg has its own
request_list and any IO allocates its request from the matching blkg
making blkcgs completely isolated in terms of request allocation.

* Root blkcg uses the request_list embedded in each request_queue,
  which was renamed to @q->root_rl from @q->rq.  While making blkcg rl
  handling a bit harier, this enables avoiding most overhead for root
  blkcg.

* Queue fullness is properly per request_list but bdi isn't blkcg
  aware yet, so congestion state currently just follows the root
  blkcg.  As writeback isn't aware of blkcg yet, this works okay for
  async congestion but readahead may get the wrong signals.  It's
  better than blkcg completely collapsing with shared request_list but
  needs to be improved with future changes.

* After this change, each block cgroup gets a full request pool making
  resource consumption of each cgroup higher.  This makes allowing
  non-root users to create cgroups less desirable; however, note that
  allowing non-root users to directly manage cgroups is already
  severely broken regardless of this patch - each block cgroup
  consumes kernel memory and skews IO weight (IO weights are not
  hierarchical).

v2: queue-sysfs.txt updated and patch description udpated as suggested
    by Vivek.

v3: blk_get_rl() wasn't checking error return from
    blkg_lookup_create() and may cause oops on lookup failure.  Fix it
    by falling back to root_rl on blkg lookup failures.  This problem
    was spotted by Rakesh Iyer <rni@google.com>.

v4: Updated to accomodate 458f27a982 "block: Avoid missed wakeup in
    request waitqueue".  blk_drain_queue() now wakes up waiters on all
    blkg->rl on the target queue.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-06-26 18:42:49 -04:00
Tejun Heo 5b788ce3e2 block: prepare for multiple request_lists
Request allocation is about to be made per-blkg meaning that there'll
be multiple request lists.

* Make queue full state per request_list.  blk_*queue_full() functions
  are renamed to blk_*rl_full() and takes @rl instead of @q.

* Rename blk_init_free_list() to blk_init_rl() and make it take @rl
  instead of @q.  Also add @gfp_mask parameter.

* Add blk_exit_rl() instead of destroying rl directly from
  blk_release_queue().

* Add request_list->q and make request alloc/free functions -
  blk_free_request(), [__]freed_request(), __get_request() - take @rl
  instead of @q.

This patch doesn't introduce any functional difference.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-06-25 11:53:52 +02:00
Tejun Heo 8a5ecdd428 block: add q->nr_rqs[] and move q->rq.elvpriv to q->nr_rqs_elvpriv
Add q->nr_rqs[] which currently behaves the same as q->rq.count[] and
move q->rq.elvpriv to q->nr_rqs_elvpriv.  blk_drain_queue() is updated
to use q->nr_rqs[] instead of q->rq.count[].

These counters separates queue-wide request statistics from the
request list and allow implementation of per-queue request allocation.

While at it, properly indent fields of struct request_list.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-06-25 11:53:51 +02:00
Tejun Heo 7f4b35d155 block: allocate io_context upfront
Block layer very lazy allocation of ioc.  It waits until the moment
ioc is absolutely necessary; unfortunately, that time could be inside
queue lock and __get_request() performs unlock - try alloc - retry
dancing.

Just allocate it up-front on entry to block layer.  We're not saving
the rain forest by deferring it to the last possible moment and
complicating things unnecessarily.

This patch is to prepare for further updates to request allocation
path.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-06-25 11:53:50 +02:00
Tejun Heo a06e05e6af block: refactor get_request[_wait]()
Currently, there are two request allocation functions - get_request()
and get_request_wait().  The former tries to allocate a request once
and the latter keeps retrying until it succeeds.  The latter wraps the
former and keeps retrying until allocation succeeds.

The combination of two functions deliver fallible non-wait allocation,
fallible wait allocation and unfailing wait allocation.  However,
given that forward progress is guaranteed, fallible wait allocation
isn't all that useful and in fact nobody uses it.

This patch simplifies the interface as follows.

* get_request() is renamed to __get_request() and is only used by the
  wrapper function.

* get_request_wait() is renamed to get_request().  It now takes
  @gfp_mask and retries iff it contains %__GFP_WAIT.

This patch doesn't introduce any functional change and is to prepare
for further updates to request allocation path.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-06-25 11:53:49 +02:00
Tejun Heo a91a5ac685 mempool: add @gfp_mask to mempool_create_node()
mempool_create_node() currently assumes %GFP_KERNEL.  Its only user,
blk_init_free_list(), is about to be updated to use other allocation
flags - add @gfp_mask argument to the function.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-06-25 11:53:47 +02:00
Asias He 5e5cfac0c6 block: Mitigate lock unbalance caused by lock switching
Commit 777eb1bf15 disconnects externally
supplied queue_lock before blk_drain_queue(). Switching the lock would
introduce lock unbalance because theads which have taken the external
lock might unlock the internal lock in the during the queue drain. This
patch mitigate this by disconnecting the lock after the queue draining
since queue draining makes a lot of request_queue users go away.

However, please note, this patch only makes the problem less likely to
happen. Anyone who still holds a ref might try to issue a new request on
a dead queue after the blk_cleanup_queue() finishes draining, the lock
unbalance might still happen in this case.

 =====================================
 [ BUG: bad unlock balance detected! ]
 3.4.0+ #288 Not tainted
 -------------------------------------
 fio/17706 is trying to release lock (&(&q->__queue_lock)->rlock) at:
 [<ffffffff81329372>] blk_queue_bio+0x2a2/0x380
 but there are no more locks to release!

 other info that might help us debug this:
 1 lock held by fio/17706:
  #0:  (&(&vblk->lock)->rlock){......}, at: [<ffffffff81327f1a>]
 get_request_wait+0x19a/0x250

 stack backtrace:
 Pid: 17706, comm: fio Not tainted 3.4.0+ #288
 Call Trace:
  [<ffffffff81329372>] ? blk_queue_bio+0x2a2/0x380
  [<ffffffff810dea49>] print_unlock_inbalance_bug+0xf9/0x100
  [<ffffffff810dfe4f>] lock_release_non_nested+0x1df/0x330
  [<ffffffff811dae24>] ? dio_bio_end_aio+0x34/0xc0
  [<ffffffff811d6935>] ? bio_check_pages_dirty+0x85/0xe0
  [<ffffffff811daea1>] ? dio_bio_end_aio+0xb1/0xc0
  [<ffffffff81329372>] ? blk_queue_bio+0x2a2/0x380
  [<ffffffff81329372>] ? blk_queue_bio+0x2a2/0x380
  [<ffffffff810e0079>] lock_release+0xd9/0x250
  [<ffffffff81a74553>] _raw_spin_unlock_irq+0x23/0x40
  [<ffffffff81329372>] blk_queue_bio+0x2a2/0x380
  [<ffffffff81328faa>] generic_make_request+0xca/0x100
  [<ffffffff81329056>] submit_bio+0x76/0xf0
  [<ffffffff8115470c>] ? set_page_dirty_lock+0x3c/0x60
  [<ffffffff811d69e1>] ? bio_set_pages_dirty+0x51/0x70
  [<ffffffff811dd1a8>] do_blockdev_direct_IO+0xbf8/0xee0
  [<ffffffff811d8620>] ? blkdev_get_block+0x80/0x80
  [<ffffffff811dd4e5>] __blockdev_direct_IO+0x55/0x60
  [<ffffffff811d8620>] ? blkdev_get_block+0x80/0x80
  [<ffffffff811d92e7>] blkdev_direct_IO+0x57/0x60
  [<ffffffff811d8620>] ? blkdev_get_block+0x80/0x80
  [<ffffffff8114c6ae>] generic_file_aio_read+0x70e/0x760
  [<ffffffff810df7c5>] ? __lock_acquire+0x215/0x5a0
  [<ffffffff811e9924>] ? aio_run_iocb+0x54/0x1a0
  [<ffffffff8114bfa0>] ? grab_cache_page_nowait+0xc0/0xc0
  [<ffffffff811e82cc>] aio_rw_vect_retry+0x7c/0x1e0
  [<ffffffff811e8250>] ? aio_fsync+0x30/0x30
  [<ffffffff811e9936>] aio_run_iocb+0x66/0x1a0
  [<ffffffff811ea9b0>] do_io_submit+0x6f0/0xb80
  [<ffffffff8134de2e>] ? trace_hardirqs_on_thunk+0x3a/0x3f
  [<ffffffff811eae50>] sys_io_submit+0x10/0x20
  [<ffffffff81a7c9e9>] system_call_fastpath+0x16/0x1b

Changes since v2: Update commit log to explain how the code is still
                  broken even if we delay the lock switching after the drain.
Changes since v1: Update commit log as Tejun suggested.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Asias He <asias@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-06-15 08:46:22 +02:00
Asias He 458f27a982 block: Avoid missed wakeup in request waitqueue
After hot-unplug a stressed disk, I found that rl->wait[] is not empty
while rl->count[] is empty and there are theads still sleeping on
get_request after the queue cleanup. With simple debug code, I found
there are exactly nr_sleep - nr_wakeup of theads in D state. So there
are missed wakeup.

  $ dmesg | grep nr_sleep
  [   52.917115] ---> nr_sleep=1046, nr_wakeup=873, delta=173
  $ vmstat 1
  1 173  0 712640  24292  96172 0 0  0  0  419  757  0  0  0 100  0

To quote Tejun:

  Ah, okay, freed_request() wakes up single waiter with the assumption
  that after the wakeup there will at least be one successful allocation
  which in turn will continue the wakeup chain until the wait list is
  empty - ie. waiter wakeup is dependent on successful request
  allocation happening after each wakeup.  With queue marked dead, any
  woken up waiter fails the allocation path, so the wakeup chaining is
  lost and we're left with hung waiters. What we need is wake_up_all()
  after drain completion.

This patch fixes the missed wakeup by waking up all the theads which
are sleeping on wait queue after queue drain.

Changes in v2: Drop waitqueue_active() optimization

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Asias He <asias@redhat.com>

Fixed a bug by me, where stacked devices would oops on calling
blk_drain_queue() since ->rq.wait[] do not get initialized unless
it's a full queue setup.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-06-15 08:45:25 +02:00
Jens Axboe 0b7877d4ee Linux 3.4-rc5
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Merge tag 'v3.4-rc5' into for-3.5/core

The core branch is behind driver commits that we want to build
on for 3.5, hence I'm pulling in a later -rc.

Linux 3.4-rc5

Conflicts:
	Documentation/feature-removal-schedule.txt

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-05-01 14:29:55 +02:00
Tejun Heo aaf7c68068 block: fix elvpriv allocation failure handling
Request allocation is mempool backed to guarantee forward progress
under memory pressure; unfortunately, this property got broken while
adding elvpriv data.  Failures during elvpriv allocation, including
ioc and icq creation failures, currently make get_request() fail as
whole.  There's no forward progress guarantee for these allocations -
they may fail indefinitely under memory pressure stalling IO and
deadlocking the system.

This patch updates get_request() such that elvpriv allocation failure
doesn't make the whole function fail.  If elvpriv allocation fails,
the allocation is degraded into !ELVPRIV.  This will force the request
to ELEVATOR_INSERT_BACK disturbing scheduling but elvpriv alloc
failures should be rare (nothing is per-request) and anything is
better than deadlocking.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-04-20 10:06:40 +02:00
Tejun Heo 29e2b09ab5 block: collapse blk_alloc_request() into get_request()
Allocation failure handling in get_request() is about to be updated.
To ease the update, collapse blk_alloc_request() into get_request().

This patch doesn't introduce any functional change.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-04-20 10:06:40 +02:00
Tejun Heo b82d4b197c blkcg: make request_queue bypassing on allocation
With the previous change to guarantee bypass visiblity for RCU read
lock regions, entering bypass mode involves non-trivial overhead and
future changes are scheduled to make use of bypass mode during init
path.  Combined it may end up adding noticeable delay during boot.

This patch makes request_queue start its life in bypass mode, which is
ended on queue init completion at the end of
blk_init_allocated_queue(), and updates blk_queue_bypass_start() such
that draining and RCU synchronization are performed only when the
queue actually enters bypass mode.

This avoids unnecessarily switching in and out of bypass mode during
init avoiding the overhead and any nasty surprises which may step from
leaving bypass mode on half-initialized queues.

The boot time overhead was pointed out by Vivek.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-04-20 10:06:06 +02:00
Tejun Heo 80fd99792b blkcg: make sure blkg_lookup() returns %NULL if @q is bypassing
Currently, blkg_lookup() doesn't check @q bypass state.  This patch
updates blk_queue_bypass_start() to do synchronize_rcu() before
returning and updates blkg_lookup() to check blk_queue_bypass() and
return %NULL if bypassing.  This ensures blkg_lookup() returns %NULL
if @q is bypassing.

This is to guarantee that nobody is accessing policy data while @q is
bypassing, which is necessary to allow replacing blkio_cgroup->pd[] in
place on policy [de]activation.

v2: Added more comments explaining bypass guarantees as suggested by
    Vivek.

v3: Added more comments explaining why there's no synchronize_rcu() in
    blk_cleanup_queue() as suggested by Vivek.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-04-20 10:06:06 +02:00
Shaohua Li 1b2e19f17e block: make auto block plug flush threshold per-disk based
We do auto block plug flush to reduce latency, the threshold is 16
requests. This works well if the task is accessing one or two drives.
The problem is if the task is accessing a raid 0 device and the raid
disk number is big, say 8 or 16, 16/8 = 2 or 16/16=1, we will have
heavy lock contention.

This patch makes the threshold per-disk based. The latency should be
still ok accessing one or two drives. The setup with application
accessing a lot of drives in the meantime uaually is big machine,
avoiding lock contention is more important, because any contention
will actually increase latency.

Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-04-06 11:37:47 -06:00
Dan Carpenter 00380a404f block: blk_alloc_queue_node(): use caller's GFP flags instead of GFP_KERNEL
We should use the GFP flags that the caller specified instead of picking
our own.  All the callers specify GFP_KERNEL so this doesn't make a
difference to how the kernel runs, it's just a cleanup.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-03-23 09:58:54 +01:00
Tejun Heo 852c788f83 block: implement bio_associate_current()
IO scheduling and cgroup are tied to the issuing task via io_context
and cgroup of %current.  Unfortunately, there are cases where IOs need
to be routed via a different task which makes scheduling and cgroup
limit enforcement applied completely incorrectly.

For example, all bios delayed by blk-throttle end up being issued by a
delayed work item and get assigned the io_context of the worker task
which happens to serve the work item and dumped to the default block
cgroup.  This is double confusing as bios which aren't delayed end up
in the correct cgroup and makes using blk-throttle and cfq propio
together impossible.

Any code which punts IO issuing to another task is affected which is
getting more and more common (e.g. btrfs).  As both io_context and
cgroup are firmly tied to task including userland visible APIs to
manipulate them, it makes a lot of sense to match up tasks to bios.

This patch implements bio_associate_current() which associates the
specified bio with %current.  The bio will record the associated ioc
and blkcg at that point and block layer will use the recorded ones
regardless of which task actually ends up issuing the bio.  bio
release puts the associated ioc and blkcg.

It grabs and remembers ioc and blkcg instead of the task itself
because task may already be dead by the time the bio is issued making
ioc and blkcg inaccessible and those are all block layer cares about.

elevator_set_req_fn() is updated such that the bio elvdata is being
allocated for is available to the elevator.

This doesn't update block cgroup policies yet.  Further patches will
implement the support.

-v2: #ifdef CONFIG_BLK_CGROUP added around bio->bi_ioc dereference in
     rq_ioc() to fix build breakage.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Kent Overstreet <koverstreet@google.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-03-06 21:27:24 +01:00
Tejun Heo 24acfc34fb block: interface update for ioc/icq creation functions
Make the following interface updates to prepare for future ioc related
changes.

* create_io_context() returning ioc only works for %current because it
  doesn't increment ref on the ioc.  Drop @task parameter from it and
  always assume %current.

* Make create_io_context_slowpath() return 0 or -errno and rename it
  to create_task_io_context().

* Make ioc_create_icq() take @ioc as parameter instead of assuming
  that of %current.  The caller, get_request(), is updated to create
  ioc explicitly and then pass it into ioc_create_icq().

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-03-06 21:27:24 +01:00
Tejun Heo b679281a64 block: restructure get_request()
get_request() is structured a bit unusually in that failure path is
inlined in the usual flow with goto labels atop and inside it.
Relocate the error path to the end of the function.

This is to prepare for icq handling changes in get_request() and
doesn't introduce any behavior change.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-03-06 21:27:24 +01:00
Tejun Heo e8989fae38 blkcg: unify blkg's for blkcg policies
Currently, blkg is per cgroup-queue-policy combination.  This is
unnatural and leads to various convolutions in partially used
duplicate fields in blkg, config / stat access, and general management
of blkgs.

This patch make blkg's per cgroup-queue and let them serve all
policies.  blkgs are now created and destroyed by blkcg core proper.
This will allow further consolidation of common management logic into
blkcg core and API with better defined semantics and layering.

As a transitional step to untangle blkg management, elvswitch and
policy [de]registration, all blkgs except the root blkg are being shot
down during elvswitch and bypass.  This patch adds blkg_root_update()
to update root blkg in place on policy change.  This is hacky and racy
but should be good enough as interim step until we get locking
simplified and switch over to proper in-place update for all blkgs.

-v2: Root blkgs need to be updated on elvswitch too and blkg_alloc()
     comment wasn't updated according to the function change.  Fixed.
     Both pointed out by Vivek.

-v3: v2 updated blkg_destroy_all() to invoke update_root_blkg_pd() for
     all policies.  This freed root pd during elvswitch before the
     last queue finished exiting and led to oops.  Directly invoke
     update_root_blkg_pd() only on BLKIO_POLICY_PROP from
     cfq_exit_queue().  This also is closer to what will be done with
     proper in-place blkg update.  Reported by Vivek.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-03-06 21:27:23 +01:00
Tejun Heo 4eef304998 blkcg: move per-queue blkg list heads and counters to queue and blkg
Currently, specific policy implementations are responsible for
maintaining list and number of blkgs.  This duplicates code
unnecessarily, and hinders factoring common code and providing blkcg
API with better defined semantics.

After this patch, request_queue hosts list heads and counters and blkg
has list nodes for both policies.  This patch only relocates the
necessary fields and the next patch will actually move management code
into blkcg core.

Note that request_queue->blkg_list[] and ->nr_blkgs[] are hardcoded to
have 2 elements.  This is to avoid include dependency and will be
removed by the next patch.

This patch doesn't introduce any behavior change.

-v2: Now unnecessary conditional on CONFIG_BLK_CGROUP_MODULE removed
     as pointed out by Vivek.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-03-06 21:27:23 +01:00
Tejun Heo 5efd611351 blkcg: add blkcg_{init|drain|exit}_queue()
Currently block core calls directly into blk-throttle for init, drain
and exit.  This patch adds blkcg_{init|drain|exit}_queue() which wraps
the blk-throttle functions.  This is to give more control and
visiblity to blkcg core layer for proper layering.  Further patches
will add logic common to blkcg policies to the functions.

While at it, collapse blk_throtl_release() into blk_throtl_exit().
There's no reason to keep them separate.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-03-06 21:27:23 +01:00
Tejun Heo f51b802c17 blkcg: use the usual get blkg path for root blkio_group
For root blkg, blk_throtl_init() was using throtl_alloc_tg()
explicitly and cfq_init_queue() was manually initializing embedded
cfqd->root_group, adding unnecessarily different code paths to blkg
handling.

Make both use the usual blkio_group get functions - throtl_get_tg()
and cfq_get_cfqg() - for the root blkio_group too.  Note that
blk_throtl_init() callsite is pushed downwards in
blk_alloc_queue_node() so that @q is sufficiently initialized for
throtl_get_tg().

This simplifies root blkg handling noticeably for cfq and will allow
further modularization of blkcg API.

-v2: Vivek pointed out that using cfq_get_cfqg() won't work if
     CONFIG_CFQ_GROUP_IOSCHED is disabled.  Fix it by factoring out
     initialization of base part of cfqg into cfq_init_cfqg_base() and
     alloc/init/free explicitly if !CONFIG_CFQ_GROUP_IOSCHED.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-03-06 21:27:22 +01:00
Tejun Heo 6ecf23afab block: extend queue bypassing to cover blkcg policies
Extend queue bypassing such that dying queue is always bypassing and
blk-throttle is drained on bypass.  With blkcg policies updated to
test blk_queue_bypass() instead of blk_queue_dead(), this ensures that
no bio or request is held by or going through blkcg policies on a
bypassing queue.

This will be used to implement blkg cleanup on elevator switches and
policy changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-03-06 21:27:22 +01:00
Tejun Heo d732580b4e block: implement blk_queue_bypass_start/end()
Rename and extend elv_queisce_start/end() to
blk_queue_bypass_start/end() which are exported and supports nesting
via @q->bypass_depth.  Also add blk_queue_bypass() to test bypass
state.

This will be further extended and used for blkio_group management.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-03-06 21:27:21 +01:00
Tejun Heo b855b04a0b block: blk-throttle should be drained regardless of q->elevator
Currently, blk_cleanup_queue() doesn't call elv_drain_elevator() if
q->elevator doesn't exist; however, bio based drivers don't have
elevator initialized but can still use blk-throttle.  This patch moves
q->elevator test inside blk_drain_queue() such that only
elv_drain_elevator() is skipped if !q->elevator.

-v2: loop can have registered queue which has NULL request_fn.  Make
     sure we don't call into __blk_run_queue() in such cases.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Vivek Goyal <vgoyal@redhat.com>

Fold in bug fix from Vivek.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-03-06 21:24:55 +01:00
Tejun Heo 07c2bd3735 block: don't call elevator callbacks for plug merges
Plug merge calls two elevator callbacks outside queue lock -
elevator_allow_merge_fn() and elevator_bio_merged_fn().  Although
attempt_plug_merge() suggests that elevator is guaranteed to be there
through the existing request on the plug list, nothing prevents plug
merge from calling into dying or initializing elevator.

For regular merges, bypass ensures elvpriv count to reach zero, which
in turn prevents merges as all !ELVPRIV requests get REQ_SOFTBARRIER
from forced back insertion.  Plug merge doesn't check ELVPRIV, and, as
the requests haven't gone through elevator insertion yet, it doesn't
have SOFTBARRIER set allowing merges on a bypassed queue.

This, for example, leads to the following crash during elevator
switch.

 BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
 IP: [<ffffffff813b34e9>] cfq_allow_merge+0x49/0xa0
 PGD 112cbc067 PUD 115d5c067 PMD 0
 Oops: 0000 [#1] PREEMPT SMP
 CPU 1
 Modules linked in: deadline_iosched

 Pid: 819, comm: dd Not tainted 3.3.0-rc2-work+ #76 Bochs Bochs
 RIP: 0010:[<ffffffff813b34e9>]  [<ffffffff813b34e9>] cfq_allow_merge+0x49/0xa0
 RSP: 0018:ffff8801143a38f8  EFLAGS: 00010297
 RAX: 0000000000000000 RBX: ffff88011817ce28 RCX: ffff880116eb6cc0
 RDX: 0000000000000000 RSI: ffff880118056e20 RDI: ffff8801199512f8
 RBP: ffff8801143a3908 R08: 0000000000000000 R09: 0000000000000000
 R10: 0000000000000001 R11: 0000000000000000 R12: ffff880118195708
 R13: ffff880118052aa0 R14: ffff8801143a3d50 R15: ffff880118195708
 FS:  00007f19f82cb700(0000) GS:ffff88011fc80000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
 CR2: 0000000000000008 CR3: 0000000112c6a000 CR4: 00000000000006e0
 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
 Process dd (pid: 819, threadinfo ffff8801143a2000, task ffff880116eb6cc0)
 Stack:
  ffff88011817ce28 ffff880118195708 ffff8801143a3928 ffffffff81391bba
  ffff88011817ce28 ffff880118195708 ffff8801143a3948 ffffffff81391bf1
  ffff88011817ce28 0000000000000000 ffff8801143a39a8 ffffffff81398e3e
 Call Trace:
  [<ffffffff81391bba>] elv_rq_merge_ok+0x4a/0x60
  [<ffffffff81391bf1>] elv_try_merge+0x21/0x40
  [<ffffffff81398e3e>] blk_queue_bio+0x8e/0x390
  [<ffffffff81396a5a>] generic_make_request+0xca/0x100
  [<ffffffff81396b04>] submit_bio+0x74/0x100
  [<ffffffff811d45c2>] __blockdev_direct_IO+0x1ce2/0x3450
  [<ffffffff811d0dc7>] blkdev_direct_IO+0x57/0x60
  [<ffffffff811460b5>] generic_file_aio_read+0x6d5/0x760
  [<ffffffff811986b2>] do_sync_read+0xe2/0x120
  [<ffffffff81199345>] vfs_read+0xc5/0x180
  [<ffffffff81199501>] sys_read+0x51/0x90
  [<ffffffff81aeac12>] system_call_fastpath+0x16/0x1b

There are multiple ways to fix this including making plug merge check
ELVPRIV; however,

* Calling into elevator outside queue lock is confusing and
  error-prone.

* Requests on plug list aren't known to the elevator.  They aren't on
  the elevator yet, so there's no elevator specific state to update.

* Given the nature of plug merges - collecting bio's for the same
  purpose from the same issuer - elevator specific restrictions aren't
  applicable.

So, simply don't call into elevator methods from plug merge by moving
elv_bio_merged() from bio_attempt_*_merge() to blk_queue_bio(), and
using blk_try_merge() in attempt_plug_merge().

This is based on Jens' patch to skip elevator_allow_merge_fn() from
plug merge.

Note that this makes per-cgroup merged stats skip plug merging.

Signed-off-by: Tejun Heo <tj@kernel.org>
LKML-Reference: <4F16F3CA.90904@kernel.dk>
Original-patch-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-02-08 09:19:42 +01:00
Tejun Heo 050c8ea80e block: separate out blk_rq_merge_ok() and blk_try_merge() from elevator functions
blk_rq_merge_ok() is the elevator-neutral part of merge eligibility
test.  blk_try_merge() determines merge direction and expects the
caller to have tested elv_rq_merge_ok() previously.

elv_rq_merge_ok() now wraps blk_rq_merge_ok() and then calls
elv_iosched_allow_merge().  elv_try_merge() is removed and the two
callers are updated to call elv_rq_merge_ok() explicitly followed by
blk_try_merge().  While at it, make rq_merge_ok() functions return
bool.

This is to prepare for plug merge update and doesn't introduce any
behavior change.

This is based on Jens' patch to skip elevator_allow_merge_fn() from
plug merge.

Signed-off-by: Tejun Heo <tj@kernel.org>
LKML-Reference: <4F16F3CA.90904@kernel.dk>
Original-patch-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-02-08 09:19:38 +01:00
Tejun Heo 11a3122f6c block: strip out locking optimization in put_io_context()
put_io_context() performed a complex trylock dancing to avoid
deferring ioc release to workqueue.  It was also broken on UP because
trylock was always assumed to succeed which resulted in unbalanced
preemption count.

While there are ways to fix the UP breakage, even the most
pathological microbench (forced ioc allocation and tight fork/exit
loop) fails to show any appreciable performance benefit of the
optimization.  Strip it out.  If there turns out to be workloads which
are affected by this change, simpler optimization from the discussion
thread can be applied later.

Signed-off-by: Tejun Heo <tj@kernel.org>
LKML-Reference: <1328514611.21268.66.camel@sli10-conroe>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-02-07 07:51:30 +01:00
Shaohua Li 05c30b9551 block: fix NULL icq_cache reference
Vivek reported a kernel crash:
[   94.217015] BUG: unable to handle kernel NULL pointer dereference at 000000000000001c
[   94.218004] IP: [<ffffffff81142fae>] kmem_cache_free+0x5e/0x200
[   94.218004] PGD 13abda067 PUD 137d52067 PMD 0
[   94.218004] Oops: 0000 [#1] SMP DEBUG_PAGEALLOC
[   94.218004] CPU 0
[   94.218004] Modules linked in: [last unloaded: scsi_wait_scan]
[   94.218004]
[   94.218004] Pid: 0, comm: swapper/0 Not tainted 3.2.0+ #16 Hewlett-Packard HP xw6600 Workstation/0A9Ch
[   94.218004] RIP: 0010:[<ffffffff81142fae>]  [<ffffffff81142fae>] kmem_cache_free+0x5e/0x200
[   94.218004] RSP: 0018:ffff88013fc03de0  EFLAGS: 00010006
[   94.218004] RAX: ffffffff81e0d020 RBX: ffff880138b3c680 RCX: 00000001801c001b
[   94.218004] RDX: 00000000003aac1d RSI: ffff880138b3c680 RDI: ffffffff81142fae
[   94.218004] RBP: ffff88013fc03e10 R08: ffff880137830238 R09: 0000000000000001
[   94.218004] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
[   94.218004] R13: ffffea0004e2cf00 R14: ffffffff812f6eb6 R15: 0000000000000246
[   94.218004] FS:  0000000000000000(0000) GS:ffff88013fc00000(0000) knlGS:0000000000000000
[   94.218004] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[   94.218004] CR2: 000000000000001c CR3: 00000001395ab000 CR4: 00000000000006f0
[   94.218004] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[   94.218004] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[   94.218004] Process swapper/0 (pid: 0, threadinfo ffffffff81e00000, task ffffffff81e0d020)
[   94.218004] Stack:
[   94.218004]  0000000000000102 ffff88013fc0db20 ffffffff81e22700 ffff880139500f00
[   94.218004]  0000000000000001 000000000000000a ffff88013fc03e20 ffffffff812f6eb6
[   94.218004]  ffff88013fc03e90 ffffffff810c8da2 ffffffff81e01fd8 ffff880137830240
[   94.218004] Call Trace:
[   94.218004]  <IRQ>
[   94.218004]  [<ffffffff812f6eb6>] icq_free_icq_rcu+0x16/0x20
[   94.218004]  [<ffffffff810c8da2>] __rcu_process_callbacks+0x1c2/0x420
[   94.218004]  [<ffffffff810c9038>] rcu_process_callbacks+0x38/0x250
[   94.218004]  [<ffffffff810405ee>] __do_softirq+0xce/0x3e0
[   94.218004]  [<ffffffff8108ed04>] ? clockevents_program_event+0x74/0x100
[   94.218004]  [<ffffffff81090104>] ? tick_program_event+0x24/0x30
[   94.218004]  [<ffffffff8183ed1c>] call_softirq+0x1c/0x30
[   94.218004]  [<ffffffff8100422d>] do_softirq+0x8d/0xc0
[   94.218004]  [<ffffffff81040c3e>] irq_exit+0xae/0xe0
[   94.218004]  [<ffffffff8183f4be>] smp_apic_timer_interrupt+0x6e/0x99
[   94.218004]  [<ffffffff8183e330>] apic_timer_interrupt+0x70/0x80

Once a queue is quiesced, it's not supposed to have any elvpriv data or
icq's, and elevator switching depends on that.  Request alloc path
followed the rule for elvpriv data but forgot apply it to icq's
leading to the following crash during elevator switch. Fix it by not
allocating icq's if ELVPRIV is not set for the request.

Reported-by: Vivek Goyal <vgoyal@redhat.com>
Tested-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-01-19 09:20:10 +01:00
Linus Torvalds b3c9dd182e Merge branch 'for-3.3/core' of git://git.kernel.dk/linux-block
* 'for-3.3/core' of git://git.kernel.dk/linux-block: (37 commits)
  Revert "block: recursive merge requests"
  block: Stop using macro stubs for the bio data integrity calls
  blockdev: convert some macros to static inlines
  fs: remove unneeded plug in mpage_readpages()
  block: Add BLKROTATIONAL ioctl
  block: Introduce blk_set_stacking_limits function
  block: remove WARN_ON_ONCE() in exit_io_context()
  block: an exiting task should be allowed to create io_context
  block: ioc_cgroup_changed() needs to be exported
  block: recursive merge requests
  block, cfq: fix empty queue crash caused by request merge
  block, cfq: move icq creation and rq->elv.icq association to block core
  block, cfq: restructure io_cq creation path for io_context interface cleanup
  block, cfq: move io_cq exit/release to blk-ioc.c
  block, cfq: move icq cache management to block core
  block, cfq: move io_cq lookup to blk-ioc.c
  block, cfq: move cfqd->icq_list to request_queue and add request->elv.icq
  block, cfq: reorganize cfq_io_context into generic and cfq specific parts
  block: remove elevator_queue->ops
  block: reorder elevator switch sequence
  ...

Fix up conflicts in:
 - block/blk-cgroup.c
	Switch from can_attach_task to can_attach
 - block/cfq-iosched.c
	conflict with now removed cic index changes (we now use q->id instead)
2012-01-15 12:24:45 -08:00
Tejun Heo 4eabc94125 block: don't kick empty queue in blk_drain_queue()
While probing, fd sets up queue, probes hardware and tears down the
queue if probing fails.  In the process, blk_drain_queue() kicks the
queue which failed to finish initialization and fd is unhappy about
that.

  floppy0: no floppy controllers found
  ------------[ cut here ]------------
  WARNING: at drivers/block/floppy.c:2929 do_fd_request+0xbf/0xd0()
  Hardware name: To Be Filled By O.E.M.
  VFS: do_fd_request called on non-open device
  Modules linked in:
  Pid: 1, comm: swapper Not tainted 3.2.0-rc4-00077-g5983fe2 #2
  Call Trace:
   [<ffffffff81039a6a>] warn_slowpath_common+0x7a/0xb0
   [<ffffffff81039b41>] warn_slowpath_fmt+0x41/0x50
   [<ffffffff813d657f>] do_fd_request+0xbf/0xd0
   [<ffffffff81322b95>] blk_drain_queue+0x65/0x80
   [<ffffffff81322c93>] blk_cleanup_queue+0xe3/0x1a0
   [<ffffffff818a809d>] floppy_init+0xdeb/0xe28
   [<ffffffff818a72b2>] ? daring+0x6b/0x6b
   [<ffffffff810002af>] do_one_initcall+0x3f/0x170
   [<ffffffff81884b34>] kernel_init+0x9d/0x11e
   [<ffffffff810317c2>] ? schedule_tail+0x22/0xa0
   [<ffffffff815dbb14>] kernel_thread_helper+0x4/0x10
   [<ffffffff81884a97>] ? start_kernel+0x2be/0x2be
   [<ffffffff815dbb10>] ? gs_change+0xb/0xb

Avoid it by making blk_drain_queue() kick queue iff dispatch queue has
something on it.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Ralf Hildebrandt <Ralf.Hildebrandt@charite.de>
Reported-by: Wu Fengguang <fengguang.wu@intel.com>
Tested-by: Sergei Trofimovich <slyich@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-12-15 20:03:04 +01:00
Tejun Heo f1f8cc9465 block, cfq: move icq creation and rq->elv.icq association to block core
Now block layer knows everything necessary to create and associate
icq's with requests.  Move ioc_create_icq() to blk-ioc.c and update
get_request() such that, if elevator_type->icq_size is set, requests
are automatically associated with their matching icq's before
elv_set_request().  io_context reference is also managed by block core
on request alloc/free.

* Only ioprio/cgroup changed handling remains from cfq_get_cic().
  Collapsed into cfq_set_request().

* This removes queue kicking on icq allocation failure (for now).  As
  icq allocation failure is rare and the only effect of queue kicking
  achieved was possibily accelerating queue processing, this change
  shouldn't be noticeable.

  There is a larger underlying problem.  Unlike request allocation,
  icq allocation is not guaranteed to succeed eventually after
  retries.  The number of icq is unbound and thus mempool can't be the
  solution either.  This effectively adds allocation dependency on
  memory free path and thus possibility of deadlock.

  This usually wouldn't happen because icq allocation is not a hot
  path and, even when the condition triggers, it's highly unlikely
  that none of the writeback workers already has icq.

  However, this is still possible especially if elevator is being
  switched under high memory pressure, so we better get it fixed.
  Probably the only solution is just bypassing elevator and appending
  to dispatch queue on any elevator allocation failure.

* Comment added to explain how icq's are managed and synchronized.

This completes cleanup of io_context interface.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-12-14 00:33:42 +01:00
Tejun Heo a612fddf0d block, cfq: move cfqd->icq_list to request_queue and add request->elv.icq
Most of icq management is about to be moved out of cfq into blk-ioc.
This patch prepares for it.

* Move cfqd->icq_list to request_queue->icq_list

* Make request explicitly point to icq instead of through elevator
  private data.  ->elevator_private[3] is replaced with sub struct elv
  which contains icq pointer and priv[2].  cfq is updated accordingly.

* Meaningless clearing of ->elevator_private[0] removed from
  elv_set_request().  At that point in code, the field was guaranteed
  to be %NULL anyway.

This patch doesn't introduce any functional change.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-12-14 00:33:41 +01:00
Tejun Heo f2dbd76a0a block, cfq: replace current_io_context() with create_io_context()
When called under queue_lock, current_io_context() triggers lockdep
warning if it hits allocation path.  This is because io_context
installation is protected by task_lock which is not IRQ safe, so it
triggers irq-unsafe-lock -> irq -> irq-safe-lock -> irq-unsafe-lock
deadlock warning.

Given the restriction, accessor + creator rolled into one doesn't work
too well.  Drop current_io_context() and let the users access
task->io_context directly inside queue_lock combined with explicit
creation using create_io_context().

Future ioc updates will further consolidate ioc access and the create
interface will be unexported.

While at it, relocate ioc internal interface declarations in blk.h and
add section comments before and after.

This patch does not introduce functional change.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-12-14 00:33:40 +01:00
Tejun Heo 09ac46c429 block: misc updates to blk_get_queue()
* blk_get_queue() is peculiar in that it returns 0 on success and 1 on
  failure instead of 0 / -errno or boolean.  Update it such that it
  returns %true on success and %false on failure.

* Make sure the caller checks for the return value.

* Separate out __blk_get_queue() which doesn't check whether @q is
  dead and put it in blk.h.  This will be used later.

This patch doesn't introduce any functional changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-12-14 00:33:38 +01:00
Tejun Heo a73f730d01 block, cfq: move cfqd->cic_index to q->id
cfq allocates per-queue id using ida and uses it to index cic radix
tree from io_context.  Move it to q->id and allocate on queue init and
free on queue release.  This simplifies cfq a bit and will allow for
further improvements of io context life-cycle management.

This patch doesn't introduce any functional difference.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-12-14 00:33:37 +01:00
Tejun Heo 8ba61435d7 block: add missing blk_queue_dead() checks
blk_insert_cloned_request(), blk_execute_rq_nowait() and
blk_flush_plug_list() either didn't check whether the queue was dead
or did it without holding queue_lock.  Update them so that dead state
is checked while holding queue_lock.

AFAICS, this plugs all holes (requeue doesn't matter as the request is
transitioning atomically from in_flight to queued).

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-12-14 00:33:37 +01:00
Tejun Heo 481a7d6479 block: fix drain_all condition in blk_drain_queue()
When trying to drain all requests, blk_drain_queue() checked only
q->rq.count[]; however, this only tracks REQ_ALLOCED requests.  This
patch updates blk_drain_queue() such that it looks at all the counters
and queues so that request_queue is actually empty on completion.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-12-14 00:33:37 +01:00
Tejun Heo 34f6055c80 block: add blk_queue_dead()
There are a number of QUEUE_FLAG_DEAD tests.  Add blk_queue_dead()
macro and use it.

This patch doesn't introduce any functional difference.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-12-14 00:33:37 +01:00
Tejun Heo 1ba64edef6 block, sx8: kill blk_insert_request()
The only user left for blk_insert_request() is sx8 and it can be
trivially switched to use blk_execute_rq_nowait() - special requests
aren't included in io stat and sx8 doesn't use block layer tagging.
Switch sx8 and kill blk_insert_requeset().

This patch doesn't introduce any functional difference.

Only compile tested.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Jeff Garzik <jgarzik@pobox.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-12-14 00:33:37 +01:00
Mike Snitzer 5151412dd4 block: initialize request_queue's numa node during
struct request_queue is allocated with __GFP_ZERO so its "node" field is
zero before initialization.  This causes an oops if node 0 is offline in
the page allocator because its zonelists are not initialized.  From Dave
Young's dmesg:

	SRAT: Node 1 PXM 2 0-d0000000
	SRAT: Node 1 PXM 2 100000000-330000000
	SRAT: Node 0 PXM 1 330000000-630000000
	Initmem setup node 1 0000000000000000-000000000affb000
	...
	Built 1 zonelists in Node order, mobility grouping on.
	...
	BUG: unable to handle kernel paging request at 0000000000001c08
	IP: [<ffffffff8111c355>] __alloc_pages_nodemask+0xb5/0x870

and __alloc_pages_nodemask+0xb5 translates to a NULL pointer on
zonelist->_zonerefs.

The fix is to initialize q->node at the time of allocation so the correct
node is passed to the slab allocator later.

Since blk_init_allocated_queue_node() is no longer needed, merge it with
blk_init_allocated_queue().

[rientjes@google.com: changelog, initializing q->node]
Cc: stable@vger.kernel.org [2.6.37+]
Reported-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Tested-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-11-23 10:59:13 +01:00
Shaohua Li 019ceb7d5d block: add missed trace_block_plug
After flush plug list, the list has no request, so we need to add a
trace_block_plug().

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Reviewed-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-11-16 09:21:50 +01:00
Shaohua Li 3540d5e89b block: avoid unnecessary plug list flush
get_request_wait() could sleep and flush the plug list.  If the list is
already flushed, don't flush again.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Reviewed-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-11-16 09:21:50 +01:00
Tejun Heo 6dd9ad7df2 block: don't call blk_drain_queue() if elevator is not up
blk_cleanup_queue() may be called before elevator is set up on a
queue which triggers the following oops.

 BUG: unable to handle kernel NULL pointer dereference at           (null)
 IP: [<ffffffff8125a69c>] elv_drain_elevator+0x1c/0x70
 ...
 Pid: 830, comm: kworker/0:2 Not tainted 3.1.0-next-20111025_64+ #1590
 Bochs Bochs
 RIP: 0010:[<ffffffff8125a69c>]  [<ffffffff8125a69c>] elv_drain_elevator+0x1c/0x70
 ...
 Call Trace:
  [<ffffffff8125da92>] blk_drain_queue+0x42/0x70
  [<ffffffff8125db90>] blk_cleanup_queue+0xd0/0x1c0
  [<ffffffff81469640>] md_free+0x50/0x70
  [<ffffffff8126f43b>] kobject_release+0x8b/0x1d0
  [<ffffffff81270d56>] kref_put+0x36/0xa0
  [<ffffffff8126f2b7>] kobject_put+0x27/0x60
  [<ffffffff814693af>] mddev_delayed_delete+0x2f/0x40
  [<ffffffff81083450>] process_one_work+0x100/0x3b0
  [<ffffffff8108527f>] worker_thread+0x15f/0x3a0
  [<ffffffff81089937>] kthread+0x87/0x90
  [<ffffffff81621834>] kernel_thread_helper+0x4/0x10

Fix it by making blk_cleanup_queue() check whether q->elevator is set
up before invoking blk_drain_queue.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-and-tested-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-11-03 18:52:11 +01:00
Jens Axboe 83157223de Merge branch 'for-linus' into for-3.2/core 2011-10-24 16:24:38 +02:00
Jeff Moyer e67b77c791 blk-flush: move the queue kick into
A dm-multipath user reported[1] a problem when trying to boot
a kernel with commit 4853abaae7
(block: fix flush machinery for stacking drivers with differring
flush flags) applied.  It turns out that an empty flush request
can be sent into blk_insert_flush.  When the BUG_ON was fixed
to allow for this, I/O on the underlying device would stall.  The
reason is that blk_insert_cloned_request does not kick the queue.
In the aforementioned commit, I had added a special case to
kick the queue if data was sent down but the queue flags did
not require a flush.  A better solution is to push the queue
kick up into blk_insert_cloned_request.

This patch, along with a follow-on which fixes the BUG_ON, fixes
the issue reported.

[1] http://www.redhat.com/archives/dm-devel/2011-September/msg00154.html

Reported-by: Christophe Saout <christophe@saout.de>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>

Stable note: 3.1
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-10-24 16:24:31 +02:00
Tao Ma 9562ad9ab3 block: Remove the control of complete cpu from bio.
bio originally has the functionality to set the complete cpu, but
it is broken.

Chirstoph said that "This code is unused, and from the all the
discussions lately pretty obviously broken.  The only thing keeping
it serves is creating more confusion and possibly more bugs."

And Jens replied with "We can kill bio_set_completion_cpu(). I'm fine
with leaving cpu control to the request based drivers, they are the
only ones that can toggle the setting anyway".

So this patch tries to remove all the work of controling complete cpu
from a bio.

Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-10-24 16:11:30 +02:00