Add throtl_grp->td so that the td (throtl_data) a given tg
(throtl_grp) belongs to can be determined, and remove @td argument
from functions which take both @td and @tg as the former now can be
determined from the latter.
This generally simplifies the code and removes a number of cases where
@td is passed as an argument without being actually used. This will
also help hierarchy support implementation.
While at it, in multi-line conditions, move the logical operators
leading broken lines to the end of the previous line.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
blk-throttle is still using function-defining macros to define flag
handling functions, which went out style at least a decade ago.
Just define the flag as bitmask and use direct bit operations.
This patch doesn't make any functional changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
throtl_rb_root will be expanded to cover more roles for hierarchy
support. Rename it to throtl_service_queue and make its fields more
descriptive.
* rb -> pending_tree
* left -> first_pending
* count -> nr_pending
* min_disptime -> first_pending_disptime
This patch is purely cosmetic.
Signed-off-by: Tejun Heo <tj@kernel.org
Acked-by: Vivek Goyal <vgoyal@redhat.com>
throtl_nr_queued() is used in several places to avoid performing
certain operations when the throtl_data is empty. This usually is
useless as those paths usually aren't traveled if there's no bio
queued.
* throtl_schedule_delayed_work() skips scheduling dispatch work item
if @td doesn't have any bios queued; however, the only case it can
be called when @td is empty is from tg_set_conf() which isn't
something we should be optimizing for.
* throtl_schedule_next_dispatch() takes a quick exit if @td is empty;
however, right after that it triggers BUG if the service tree is
empty. The two conditions are equivalent and it can just test
@st->count for the quick exit.
* blk_throtl_dispatch_work_fn() skips dispatch if @td is empty. This
work function isn't usually invoked when @td is empty. The only
possibility is from tg_set_conf() and when it happens the normal
dispatching path can handle empty @td fine. No need to add special
skip path.
This patch removes the above three unnecessary optimizations, which
leave throtl_log() call in blk_throtl_dispatch_work_fn() the only user
of throtl_nr_queued(). Remove throtl_nr_queued() and open code it in
throtl_log(). I don't think we need td->nr_queued[] at all. Maybe we
can remove it later.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Move throtl_schedule_delayed_work() above its first user so that the
forward declaration can be removed.
This patch is pure relocaiton.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
blk-throttle is about to go through major restructuring to support
hierarchy. Do cosmetic updates in preparation.
* s/throtl_data->throtl_work/throtl_data->dispatch_work/
* s/blk_throtl_work()/blk_throtl_dispatch_work_fn()/
* Collapse throtl_dispatch() into blk_throtl_dispatch_work_fn()
This patch is purely cosmetic.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
When bps or iops configuration changes, blk-throttle records the new
configuration and sets a flag indicating that the config has changed.
The flag is checked in the bio dispatch path and applied. This
deferred config application was necessary due to limitations in blkcg
framework, which haven't existed for quite a while now.
This patch removes the deferred config application mechanism and
applies new configurations directly from tg_set_conf(), which is
simpler.
v2: Dropped unnecessary throtl_schedule_delayed_work() call from
tg_set_conf() as suggested by Vivek Goyal.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
throtl_select_dispatch() calls throtl_enqueue_tg() right after
tg_update_disptime(), which always calls the function anyway. The
call is, while harmless, unnecessary. Remove it.
This patch doesn't introduce any behavior difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Currently, when the last reference of a blkcg_gq is put, all then
release operations sans the actual freeing happen directly in
blkg_put(). As blkg_put() may be called under queue_lock, all
pd_exit_fn()s may be too. This makes it impossible for pd_exit_fn()s
to use del_timer_sync() on timers which grab the queue_lock which is
an irq-safe lock due to the deadlock possibility described in the
comment on top of del_timer_sync().
This can be easily avoided by perfoming the release operations in the
RCU callback instead of directly from blkg_put(). This patch moves
the blkcg_gq release operations to the RCU callback.
As this leaves __blkg_release() with only call_rcu() invocation,
blkg_rcu_free() is renamed to __blkg_release_rcu(), exported and
call_rcu() invocation is now done directly from blkg_put() instead of
going through __blkg_release() which is removed.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Currently, when creating a new blkcg_gq, each policy's pd_init_fn() is
invoked in blkg_alloc() before the parent is linked. This makes it
difficult for policies to perform initializations which are dependent
on the parent.
This patch moves pd_init_fn() invocations to blkg_create() after the
parent blkg is linked where the new blkg is fully initialized. As
this means that blkg_free() can't assume that pd's are initialized,
pd_exit_fn() invocations are moved to __blkg_release(). This
guarantees that pd_exit_fn() is also invoked with fully initialized
blkgs with valid parent pointers.
This will help implementing hierarchy support in blk-throttle.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
blk-throttle hierarchy support will make use of it. Move
blkg_for_each_descendant_pre() from block/blk-cgroup.c to
block/blk-cgroup.h.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
In blkg_create(), after lookup of parent fails, the control jumps to
error path with the error code encoded into @blkg. The error path
doesn't use @blkg for the return value. It returns ERR_PTR(ret).
Make lookup fail path set @ret instead of @blkg.
Note that the parent lookup is guaranteed to succeed at that point and
the condition check is purely for sanity and triggers WARN when fails.
As such, I don't think it's necessary to mark it for -stable.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Block layer uses workqueues for multiple purposes. There is no real dependency
of scheduling these on the cpu which scheduled them.
On a idle system, it is observed that and idle cpu wakes up many times just to
service this work. It would be better if we can schedule it on a cpu which the
scheduler believes to be the most appropriate one.
This patch replaces normal workqueues with power efficient versions.
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
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()
...
I dived into lguest again, reworking the pagetable code so we can move
the switcher page: our fixmaps sometimes take more than 2MB now...
Cheers,
Rusty.
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Merge tag 'virtio-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux
Pull virtio & lguest updates from Rusty Russell:
"Lots of virtio work which wasn't quite ready for last merge window.
Plus I dived into lguest again, reworking the pagetable code so we can
move the switcher page: our fixmaps sometimes take more than 2MB now..."
Ugh. Annoying conflicts with the tcm_vhost -> vhost_scsi rename.
Hopefully correctly resolved.
* tag 'virtio-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux: (57 commits)
caif_virtio: Remove bouncing email addresses
lguest: improve code readability in lg_cpu_start.
virtio-net: fill only rx queues which are being used
lguest: map Switcher below fixmap.
lguest: cache last cpu we ran on.
lguest: map Switcher text whenever we allocate a new pagetable.
lguest: don't share Switcher PTE pages between guests.
lguest: expost switcher_pages array (as lg_switcher_pages).
lguest: extract shadow PTE walking / allocating.
lguest: make check_gpte et. al return bool.
lguest: assume Switcher text is a single page.
lguest: rename switcher_page to switcher_pages.
lguest: remove RESERVE_MEM constant.
lguest: check vaddr not pgd for Switcher protection.
lguest: prepare to make SWITCHER_ADDR a variable.
virtio: console: replace EMFILE with EBUSY for already-open port
virtio-scsi: reset virtqueue affinity when doing cpu hotplug
virtio-scsi: introduce multiqueue support
virtio-scsi: push vq lock/unlock into virtscsi_vq_done
virtio-scsi: pass struct virtio_scsi to virtqueue completion function
...
In alloc_read_gpt_entries and alloc_read_gpt_header, the kzalloc'ated
zones are either totally overwritten by the following read_lba call,
or freed. As kmalloc is cheaper than kzalloc, use kmalloc.
Signed-off-by: Philippe De Muyter <phdm@macqel.be>
Cc: Matt Domsch <Matt_Domsch@dell.com>
Cc: Panagiotis Issaris <takis@issaris.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull cgroup updates from Tejun Heo:
- Fixes and a lot of cleanups. Locking cleanup is finally complete.
cgroup_mutex is no longer exposed to individual controlelrs which
used to cause nasty deadlock issues. Li fixed and cleaned up quite a
bit including long standing ones like racy cgroup_path().
- device cgroup now supports proper hierarchy thanks to Aristeu.
- perf_event cgroup now supports proper hierarchy.
- A new mount option "__DEVEL__sane_behavior" is added. As indicated
by the name, this option is to be used for development only at this
point and generates a warning message when used. Unfortunately,
cgroup interface currently has too many brekages and inconsistencies
to implement a consistent and unified hierarchy on top. The new flag
is used to collect the behavior changes which are necessary to
implement consistent unified hierarchy. It's likely that this flag
won't be used verbatim when it becomes ready but will be enabled
implicitly along with unified hierarchy.
The option currently disables some of broken behaviors in cgroup core
and also .use_hierarchy switch in memcg (will be routed through -mm),
which can be used to make very unusual hierarchy where nesting is
partially honored. It will also be used to implement hierarchy
support for blk-throttle which would be impossible otherwise without
introducing a full separate set of control knobs.
This is essentially versioning of interface which isn't very nice but
at this point I can't see any other options which would allow keeping
the interface the same while moving towards hierarchy behavior which
is at least somewhat sane. The planned unified hierarchy is likely
to require some level of adaptation from userland anyway, so I think
it'd be best to take the chance and update the interface such that
it's supportable in the long term.
Maintaining the existing interface does complicate cgroup core but
shouldn't put too much strain on individual controllers and I think
it'd be manageable for the foreseeable future. Maybe we'll be able
to drop it in a decade.
Fix up conflicts (including a semantic one adding a new #include to ppc
that was uncovered by header the file changes) as per Tejun.
* 'for-3.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (45 commits)
cpuset: fix compile warning when CONFIG_SMP=n
cpuset: fix cpu hotplug vs rebuild_sched_domains() race
cpuset: use rebuild_sched_domains() in cpuset_hotplug_workfn()
cgroup: restore the call to eventfd->poll()
cgroup: fix use-after-free when umounting cgroupfs
cgroup: fix broken file xattrs
devcg: remove parent_cgroup.
memcg: force use_hierarchy if sane_behavior
cgroup: remove cgrp->top_cgroup
cgroup: introduce sane_behavior mount option
move cgroupfs_root to include/linux/cgroup.h
cgroup: convert cgroupfs_root flag bits to masks and add CGRP_ prefix
cgroup: make cgroup_path() not print double slashes
Revert "cgroup: remove bind() method from cgroup_subsys."
perf: make perf_event cgroup hierarchical
cgroup: implement cgroup_is_descendant()
cgroup: make sure parent won't be destroyed before its children
cgroup: remove bind() method from cgroup_subsys.
devcg: remove broken_hierarchy tag
cgroup: remove cgroup_lock_is_held()
...
Here's the merge request for the driver core tree for 3.10-rc1
It's pretty small, just a number of driver core and sysfs updates and
fixes, all of which have been in linux-next for a while now.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'driver-core-3.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
Pull driver core update from Greg Kroah-Hartman:
"Here's the merge request for the driver core tree for 3.10-rc1
It's pretty small, just a number of driver core and sysfs updates and
fixes, all of which have been in linux-next for a while now.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>"
Fixed conflict in kernel/rtmutex-tester.c, the locking tree had a better
fix for the same sysfs file mode problem.
* tag 'driver-core-3.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
PM / Runtime: Idle devices asynchronously after probe|release
driver core: handle user namespaces properly with the uid/gid devtmpfs change
driver core: devtmpfs: fix compile failure with CONFIG_UIDGID_STRICT_TYPE_CHECKS
devtmpfs: add base.h include
driver core: add uid and gid to devtmpfs
sysfs: check if one entry has been removed before freeing
sysfs: fix crash_notes_size build warning
sysfs: fix use after free in case of concurrent read/write and readdir
rtmutex-tester: fix mode of sysfs files
Documentation: Add ABI entry for crash_notes and crash_notes_size
sysfs: Add crash_notes_size to export percpu note size
driver core: platform_device.h: fix checkpatch errors and warnings
driver core: platform.c: fix checkpatch errors and warnings
driver core: warn that platform_driver_probe can not use deferred probing
sysfs: use atomic_inc_unless_negative in sysfs_get_active
base: core: WARN() about bogus permissions on device attributes
device: separate all subsys mutexes
This reverts commit 3a366e614d.
Wanlong Gao reports that it causes a kernel panic on his machine several
minutes after boot. Reverting it removes the panic.
Jens says:
"It's not quite clear why that is yet, so I think we should just revert
the commit for 3.9 final (which I'm assuming is pretty close).
The wifi is crap at the LSF hotel, so sending this email instead of
queueing up a revert and pull request."
Reported-by: Wanlong Gao <gaowanlong@cn.fujitsu.com>
Requested-by: Jens Axboe <axboe@kernel.dk>
Cc: Tejun Heo <tj@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now that devtmpfs is caring about uid/gid, we need to use the correct
internal types so users who have USER_NS enabled will have things work
properly for them.
Thanks to Eric for pointing this out, and the patch review.
Reported-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kay Sievers <kay@vrfy.org>
Cc: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Some drivers want to tell userspace what uid and gid should be used for
their device nodes, so allow that information to percolate through the
driver core to userspace in order to make this happen. This means that
some systems (i.e. Android and friends) will not need to even run a
udev-like daemon for their device node manager and can just rely in
devtmpfs fully, reducing their footprint even more.
Signed-off-by: Kay Sievers <kay@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 8761a3dc1f.
There are situations where the destruction path is called
with the bdev->bd_mutex already held, which then deadlocks in
loop_clr_fd(). The normal partition cleanup does a trylock()
on the mutex, but it'd be nice to have a more bullet proof
method in loop. So punt this more involved fix to the next
merge window, and just back out this buggy fix for now.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
As found by gcc-4.8, the QUEUE_SYSFS_BIT_FNS macro creates functions
that use a value generated by queue_var_store independent of whether
that value was set or not.
block/blk-sysfs.c: In function 'queue_store_nonrot':
block/blk-sysfs.c:244:385: warning: 'val' may be used uninitialized in this function [-Wmaybe-uninitialized]
Unlike most other such warnings, this one is not a false positive,
writing any non-number string into the sysfs files indeed has
an undefined result, rather than returning an error.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Tejun writes:
-----
This is the pull request for the earlier patchset[1] with the same
name. It's only three patches (the first one was committed to
workqueue tree) but the merge strategy is a bit involved due to the
dependencies.
* Because the conversion needs features from wq/for-3.10,
block/for-3.10/core is based on rc3, and wq/for-3.10 has conflicts
with rc3, I pulled mainline (rc5) into wq/for-3.10 to prevent those
workqueue conflicts from flaring up in block tree.
* Resolving the issue that Jan and Dave raised about debugging
requires arch-wide changes. The patchset is being worked on[2] but
it'll have to go through -mm after these changes show up in -next,
and not included in this pull request.
The three commits are located in the following git branch.
git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq.git writeback-workqueue
Pulling it into block/for-3.10/core produces a conflict in
drivers/md/raid5.c between the following two commits.
e3620a3ad5 ("MD RAID5: Avoid accessing gendisk or queue structs when not available")
2f6db2a707 ("raid5: use bio_reset()")
The conflict is trivial - one removes an "if ()" conditional while the
other removes "rbi->bi_next = NULL" right above it. We just need to
remove both. The merged branch is available at
git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq.git block-test-merge
so that you can use it for verification. The test merge commit has
proper merge description.
While these changes are a bit of pain to route, they make code simpler
and even have, while minute, measureable performance gain[3] even on a
workload which isn't particularly favorable to showing the benefits of
this conversion.
----
Fixed up the conflict.
Conflicts:
drivers/md/raid5.c
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Just a little convenience macro - main reason to add it now is preparing
for immutable bio vecs, it'll reduce the size of the patch that puts
bi_sector/bi_size/bi_idx into a struct bvec_iter.
Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
CC: Lars Ellenberg <drbd-dev@lists.linbit.com>
CC: Jiri Kosina <jkosina@suse.cz>
CC: Alasdair Kergon <agk@redhat.com>
CC: dm-devel@redhat.com
CC: Neil Brown <neilb@suse.de>
CC: Martin Schwidefsky <schwidefsky@de.ibm.com>
CC: Heiko Carstens <heiko.carstens@de.ibm.com>
CC: linux-s390@vger.kernel.org
CC: Chris Mason <chris.mason@fusionio.com>
CC: Steven Whitehouse <swhiteho@redhat.com>
Acked-by: Steven Whitehouse <swhiteho@redhat.com>
Converts it to use bio_advance(), simplifying it quite a bit in the
process.
Note that req_bio_endio() now always calls bio_advance() - which means
it always loops over the biovec, not just on partial completions. Don't
expect it to affect performance, but worth noting.
Tested it by forcing partial updates, and dumping before and after on
various bio/bvec fields when doing a partial update.
Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
When a request is added:
If device is suspended or is suspending and the request is not a
PM request, resume the device.
When the last request finishes:
Call pm_runtime_mark_last_busy().
When pick a request:
If device is resuming/suspending, then only PM request is allowed
to go.
The idea and API is designed by Alan Stern and described here:
http://marc.info/?l=linux-scsi&m=133727953625963&w=2
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add runtime pm helper functions:
void blk_pm_runtime_init(struct request_queue *q, struct device *dev)
- Initialization function for drivers to call.
int blk_pre_runtime_suspend(struct request_queue *q)
- If any requests are in the queue, mark last busy and return -EBUSY.
Otherwise set q->rpm_status to RPM_SUSPENDING and return 0.
void blk_post_runtime_suspend(struct request_queue *q, int err)
- If the suspend succeeded then set q->rpm_status to RPM_SUSPENDED.
Otherwise set it to RPM_ACTIVE and mark last busy.
void blk_pre_runtime_resume(struct request_queue *q)
- Set q->rpm_status to RPM_RESUMING.
void blk_post_runtime_resume(struct request_queue *q, int err)
- If the resume succeeded then set q->rpm_status to RPM_ACTIVE
and call __blk_run_queue, then mark last busy and autosuspend.
Otherwise set q->rpm_status to RPM_SUSPENDED.
The idea and API is designed by Alan Stern and described here:
http://marc.info/?l=linux-scsi&m=133727953625963&w=2
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Any partitions added by user space to the loop device were being
left in place after detaching the loop device. This was because
the detach path issued a BLKRRPART to clean up partitions if
LO_FLAGS_PARTSCAN was set, meaning that the partitions were auto
scanned on attach. Replace this BLKRRPART with code that
unconditionally cleans up partitions on detach instead.
Signed-off-by: Phillip Susi <psusi@ubuntu.com>
Modified by Jens to export delete_partition().
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This is useful in places that recycle the same scatterlist multiple
times, and do not want to incur the cost of sg_init_table every
time in hot paths.
Acked-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
rename() will change dentry->d_name. The result of this race can
be worse than seeing partially rewritten name, but we might access
a stale pointer because rename() will re-allocate memory to hold
a longer name.
As accessing dentry->name must be protected by dentry->d_lock or
parent inode's i_mutex, while on the other hand cgroup-path() can
be called with some irq-safe spinlocks held, we can't generate
cgroup path using dentry->d_name.
Alternatively we make a copy of dentry->d_name and save it in
cgrp->name when a cgroup is created, and update cgrp->name at
rename().
v5: use flexible array instead of zero-size array.
v4: - allocate root_cgroup_name and all root_cgroup->name points to it.
- add cgroup_name() wrapper.
v3: use kfree_rcu() instead of synchronize_rcu() in user-visible path.
v2: make cgrp->name RCU safe.
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Pull block IO core bits from Jens Axboe:
"Below are the core block IO bits for 3.9. It was delayed a few days
since my workstation kept crashing every 2-8h after pulling it into
current -git, but turns out it is a bug in the new pstate code (divide
by zero, will report separately). In any case, it contains:
- The big cfq/blkcg update from Tejun and and Vivek.
- Additional block and writeback tracepoints from Tejun.
- Improvement of the should sort (based on queues) logic in the plug
flushing.
- _io() variants of the wait_for_completion() interface, using
io_schedule() instead of schedule() to contribute to io wait
properly.
- Various little fixes.
You'll get two trivial merge conflicts, which should be easy enough to
fix up"
Fix up the trivial conflicts due to hlist traversal cleanups (commit
b67bfe0d42: "hlist: drop the node parameter from iterators").
* 'for-3.9/core' of git://git.kernel.dk/linux-block: (39 commits)
block: remove redundant check to bd_openers()
block: use i_size_write() in bd_set_size()
cfq: fix lock imbalance with failed allocations
drivers/block/swim3.c: fix null pointer dereference
block: don't select PERCPU_RWSEM
block: account iowait time when waiting for completion of IO request
sched: add wait_for_completion_io[_timeout]
writeback: add more tracepoints
block: add block_{touch|dirty}_buffer tracepoint
buffer: make touch_buffer() an exported function
block: add @req to bio_{front|back}_merge tracepoints
block: add missing block_bio_complete() tracepoint
block: Remove should_sort judgement when flush blk_plug
block,elevator: use new hashtable implementation
cfq-iosched: add hierarchical cfq_group statistics
cfq-iosched: collect stats from dead cfqgs
cfq-iosched: separate out cfqg_stats_reset() from cfq_pd_reset_stats()
blkcg: make blkcg_print_blkgs() grab q locks instead of blkcg lock
block: RCU free request_queue
blkcg: implement blkg_[rw]stat_recursive_sum() and blkg_[rw]stat_merge()
...
I'm not sure why, but the hlist for each entry iterators were conceived
list_for_each_entry(pos, head, member)
The hlist ones were greedy and wanted an extra parameter:
hlist_for_each_entry(tpos, pos, head, member)
Why did they need an extra pos parameter? I'm not quite sure. Not only
they don't really need it, it also prevents the iterator from looking
exactly like the list iterator, which is unfortunate.
Besides the semantic patch, there was some manual work required:
- Fix up the actual hlist iterators in linux/list.h
- Fix up the declaration of other iterators based on the hlist ones.
- A very small amount of places were using the 'node' parameter, this
was modified to use 'obj->member' instead.
- Coccinelle didn't handle the hlist_for_each_entry_safe iterator
properly, so those had to be fixed up manually.
The semantic patch which is mostly the work of Peter Senna Tschudin is here:
@@
iterator name hlist_for_each_entry, hlist_for_each_entry_continue, hlist_for_each_entry_from, hlist_for_each_entry_rcu, hlist_for_each_entry_rcu_bh, hlist_for_each_entry_continue_rcu_bh, for_each_busy_worker, ax25_uid_for_each, ax25_for_each, inet_bind_bucket_for_each, sctp_for_each_hentry, sk_for_each, sk_for_each_rcu, sk_for_each_from, sk_for_each_safe, sk_for_each_bound, hlist_for_each_entry_safe, hlist_for_each_entry_continue_rcu, nr_neigh_for_each, nr_neigh_for_each_safe, nr_node_for_each, nr_node_for_each_safe, for_each_gfn_indirect_valid_sp, for_each_gfn_sp, for_each_host;
type T;
expression a,c,d,e;
identifier b;
statement S;
@@
-T b;
<+... when != b
(
hlist_for_each_entry(a,
- b,
c, d) S
|
hlist_for_each_entry_continue(a,
- b,
c) S
|
hlist_for_each_entry_from(a,
- b,
c) S
|
hlist_for_each_entry_rcu(a,
- b,
c, d) S
|
hlist_for_each_entry_rcu_bh(a,
- b,
c, d) S
|
hlist_for_each_entry_continue_rcu_bh(a,
- b,
c) S
|
for_each_busy_worker(a, c,
- b,
d) S
|
ax25_uid_for_each(a,
- b,
c) S
|
ax25_for_each(a,
- b,
c) S
|
inet_bind_bucket_for_each(a,
- b,
c) S
|
sctp_for_each_hentry(a,
- b,
c) S
|
sk_for_each(a,
- b,
c) S
|
sk_for_each_rcu(a,
- b,
c) S
|
sk_for_each_from
-(a, b)
+(a)
S
+ sk_for_each_from(a) S
|
sk_for_each_safe(a,
- b,
c, d) S
|
sk_for_each_bound(a,
- b,
c) S
|
hlist_for_each_entry_safe(a,
- b,
c, d, e) S
|
hlist_for_each_entry_continue_rcu(a,
- b,
c) S
|
nr_neigh_for_each(a,
- b,
c) S
|
nr_neigh_for_each_safe(a,
- b,
c, d) S
|
nr_node_for_each(a,
- b,
c) S
|
nr_node_for_each_safe(a,
- b,
c, d) S
|
- for_each_gfn_sp(a, c, d, b) S
+ for_each_gfn_sp(a, c, d) S
|
- for_each_gfn_indirect_valid_sp(a, c, d, b) S
+ for_each_gfn_indirect_valid_sp(a, c, d) S
|
for_each_host(a,
- b,
c) S
|
for_each_host_safe(a,
- b,
c, d) S
|
for_each_mesh_entry(a,
- b,
c, d) S
)
...+>
[akpm@linux-foundation.org: drop bogus change from net/ipv4/raw.c]
[akpm@linux-foundation.org: drop bogus hunk from net/ipv6/raw.c]
[akpm@linux-foundation.org: checkpatch fixes]
[akpm@linux-foundation.org: fix warnings]
[akpm@linux-foudnation.org: redo intrusive kvm changes]
Tested-by: Peter Senna Tschudin <peter.senna@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, sizeof(struct parsed_partitions) may be 64KB in 32bit arch, so
it is easy to trigger page allocation failure by check_partition,
especially in hotplug block device situation(such as, USB mass storage,
MMC card, ...), and Felipe Balbi has observed the failure.
This patch does below optimizations on the allocation of struct
parsed_partitions to try to address the issue:
- make parsed_partitions.parts as pointer so that the pointed memory can
fit in 32KB buffer, then approximate 32KB memory can be saved
- vmalloc the buffer pointed by parsed_partitions.parts because 32KB is
still a bit big for kmalloc
- given that many devices have the partition count limit, so only
allocate disk_max_parts() partitions instead of 256 partitions always
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Reported-by: Felipe Balbi <balbi@ti.com>
Cc: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It isn't necessary to read the information of partitions whose number is
equal and more than state->limit since only maximum state->limit
partitions will be added inside rescan_partitions().
That is also what other kind of partitions are doing.
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
UEFI 2.3.1D will include a change to the spec language mandating that a
GPT header must be greater than *or equal to* the size of the defined
structure. While verifying that this would work on Linux, I discovered
that we're not actually checking the minimum bound at all.
The result of this is that when we verify the checksum, it's possible that
on a malformed header (with header_size of 0), we won't actually verify
any data.
[akpm@linux-foundation.org: fix printk warning]
Signed-off-by: Peter Jones <pjones@redhat.com>
Acked-by: Matt Fleming <matt.fleming@intel.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
AIX formatted disks do not always have the MSDOS 55aa signature.
This happens e.g. for unbootable AIX disks.
Up to now, such disks were not recognized as AIX disks, because of the
missing 55aa. Fix that by inverting the two tests. Let's first
check for the AIX magic strings, and only if that fails check for
the MSDOS magic word.
Signed-off-by: Philippe De Muyter <phdm@macqel.be>
Cc: Andreas Mohr <andi@lisas.de>
Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Olaf Hering <olh@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Convert to the much saner new idr interface. Both bsg and genhd
protect idr w/ mutex making preloading unnecessary.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
idr allocation in blk_alloc_devt() wasn't synchronized against lookup
and removal, and its limit check was off by one - 1 << MINORBITS is
the number of minors allowed, not the maximum allowed minor.
Add locking and rename MAX_EXT_DEVT to NR_EXT_DEVT and fix limit
checking.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
While adding and removing a lot of disks disks and partitions this
sometimes shows up:
WARNING: at fs/sysfs/dir.c:512 sysfs_add_one+0xc9/0x130() (Not tainted)
Hardware name:
sysfs: cannot create duplicate filename '/dev/block/259:751'
Modules linked in: raid1 autofs4 bnx2fc cnic uio fcoe libfcoe libfc 8021q scsi_transport_fc scsi_tgt garp stp llc sunrpc cpufreq_ondemand powernow_k8 freq_table mperf ipv6 dm_mirror dm_region_hash dm_log power_meter microcode dcdbas serio_raw amd64_edac_mod edac_core edac_mce_amd i2c_piix4 i2c_core k10temp bnx2 sg ixgbe dca mdio ext4 mbcache jbd2 dm_round_robin sr_mod cdrom sd_mod crc_t10dif ata_generic pata_acpi pata_atiixp ahci mptsas mptscsih mptbase scsi_transport_sas dm_multipath dm_mod [last unloaded: scsi_wait_scan]
Pid: 44103, comm: async/16 Not tainted 2.6.32-195.el6.x86_64 #1
Call Trace:
warn_slowpath_common+0x87/0xc0
warn_slowpath_fmt+0x46/0x50
sysfs_add_one+0xc9/0x130
sysfs_do_create_link+0x12b/0x170
sysfs_create_link+0x13/0x20
device_add+0x317/0x650
idr_get_new+0x13/0x50
add_partition+0x21c/0x390
rescan_partitions+0x32b/0x470
sd_open+0x81/0x1f0 [sd_mod]
__blkdev_get+0x1b6/0x3c0
blkdev_get+0x10/0x20
register_disk+0x155/0x170
add_disk+0xa6/0x160
sd_probe_async+0x13b/0x210 [sd_mod]
add_wait_queue+0x46/0x60
async_thread+0x102/0x250
default_wake_function+0x0/0x20
async_thread+0x0/0x250
kthread+0x96/0xa0
child_rip+0xa/0x20
kthread+0x0/0xa0
child_rip+0x0/0x20
This most likely happens because dev_t is freed while the number is
still used and idr_get_new() is not protected on every use. The fix
adds a mutex where it wasn't before and moves the dev_t free function so
it is called after device del.
Signed-off-by: Tomas Henzl <thenzl@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Apply the introduced pm_runtime_set_memalloc_noio on block device so
that PM core will teach mm to not allocate memory with GFP_IOFS when
calling the runtime_resume and runtime_suspend callback for block
devices and its ancestors.
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Oliver Neukum <oneukum@suse.de>
Cc: Jiri Kosina <jiri.kosina@suse.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Greg KH <greg@kroah.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: David Decotigny <david.decotigny@google.com>
Cc: Tom Herbert <therbert@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
While stress-running very-small container scenarios with the Kernel Memory
Controller, I've run into a lockdep-detected lock imbalance in
cfq-iosched.c.
I'll apologize beforehand for not posting a backlog: I didn't anticipate
it would be so hard to reproduce, so I didn't save my serial output and
went directly on debugging. Turns out that it did not happen again in
more than 20 runs, making it a quite rare pattern.
But here is my analysis:
When we are in very low-memory situations, we will arrive at
cfq_find_alloc_queue and may not find a queue, having to resort to the oom
queue, in an rcu-locked condition:
if (!cfqq || cfqq == &cfqd->oom_cfqq)
[ ... ]
Next, we will release the rcu lock, and try to allocate a queue, retrying
if we succeed:
rcu_read_unlock();
spin_unlock_irq(cfqd->queue->queue_lock);
new_cfqq = kmem_cache_alloc_node(cfq_pool,
gfp_mask | __GFP_ZERO,
cfqd->queue->node);
spin_lock_irq(cfqd->queue->queue_lock);
if (new_cfqq)
goto retry;
We are unlocked at this point, but it should be fine, since we will
reacquire the rcu_read_lock when we retry.
Except of course, that we may not retry: the allocation may very well fail
and we'll keep on going through the flow:
The next branch is:
if (cfqq) {
[ ... ]
} else
cfqq = &cfqd->oom_cfqq;
And right before exiting, we'll issue rcu_read_unlock().
Being already unlocked, this is the likely source of our imbalance. Since
cfqq is either already NULL or made NULL in the first statement of the
outter branch, the only viable alternative here seems to be to return the
oom queue right away in case of allocation failure.
Please review the following patch and apply if you agree with my analysis.
Signed-off-by: Glauber Costa <glommer@parallels.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The block device doesn't use percpu rw-semaphore anymore, so don't select
it for compilation.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This provides a band-aid to provide stable page writes on jbd without
needing to backport the fixed locking and page writeback bit handling
schemes of jbd2. The band-aid works by using bounce buffers to snapshot
page contents instead of waiting.
For those wondering about the ext3 bandage -- fixing the jbd locking
(which was done as part of ext4dev years ago) is a lot of surgery, and
setting PG_writeback on data pages when we actually hold the page lock
dropped ext3 performance by nearly an order of magnitude. If we're
going to migrate iscsi and raid to use stable page writes, the
complaints about high latency will likely return. We might as well
centralize their page snapshotting thing to one place.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Tested-by: Andy Lutomirski <luto@amacapital.net>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Artem Bityutskiy <dedekind1@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Eric Van Hensbergen <ericvh@gmail.com>
Cc: Ron Minnich <rminnich@sandia.gov>
Cc: Latchesar Ionkov <lucho@ionkov.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patchset ("stable page writes, part 2") makes some key
modifications to the original 'stable page writes' patchset. First, it
provides creators (devices and filesystems) of a backing_dev_info a flag
that declares whether or not it is necessary to ensure that page
contents cannot change during writeout. It is no longer assumed that
this is true of all devices (which was never true anyway). Second, the
flag is used to relaxed the wait_on_page_writeback calls so that wait
only occurs if the device needs it. Third, it fixes up the remaining
disk-backed filesystems to use this improved conditional-wait logic to
provide stable page writes on those filesystems.
It is hoped that (for people not using checksumming devices, anyway)
this patchset will give back unnecessary performance decreases since the
original stable page write patchset went into 3.0. Sorry about not
fixing it sooner.
Complaints were registered by several people about the long write
latencies introduced by the original stable page write patchset.
Generally speaking, the kernel ought to allocate as little extra memory
as possible to facilitate writeout, but for people who simply cannot
wait, a second page stability strategy is (re)introduced: snapshotting
page contents. The waiting behavior is still the default strategy; to
enable page snapshotting, a superblock flag (MS_SNAP_STABLE) must be
set. This flag is used to bandaid^Henable stable page writeback on
ext3[1], and is not used anywhere else.
Given that there are already a few storage devices and network FSes that
have rolled their own page stability wait/page snapshot code, it would
be nice to move towards consolidating all of these. It seems possible
that iscsi and raid5 may wish to use the new stable page write support
to enable zero-copy writeout.
Thank you to Jan Kara for helping fix a couple more filesystems.
Per Andrew Morton's request, here are the result of using dbench to measure
latencies on ext2:
3.8.0-rc3:
Operation Count AvgLat MaxLat
----------------------------------------
WriteX 109347 0.028 59.817
ReadX 347180 0.004 3.391
Flush 15514 29.828 287.283
Throughput 57.429 MB/sec 4 clients 4 procs max_latency=287.290 ms
3.8.0-rc3 + patches:
WriteX 105556 0.029 4.273
ReadX 335004 0.005 4.112
Flush 14982 30.540 298.634
Throughput 55.4496 MB/sec 4 clients 4 procs max_latency=298.650 ms
As you can see, for ext2 the maximum write latency decreases from ~60ms
on a laptop hard disk to ~4ms. I'm not sure why the flush latencies
increase, though I suspect that being able to dirty pages faster gives
the flusher more work to do.
On ext4, the average write latency decreases as well as all the maximum
latencies:
3.8.0-rc3:
WriteX 85624 0.152 33.078
ReadX 272090 0.010 61.210
Flush 12129 36.219 168.260
Throughput 44.8618 MB/sec 4 clients 4 procs max_latency=168.276 ms
3.8.0-rc3 + patches:
WriteX 86082 0.141 30.928
ReadX 273358 0.010 36.124
Flush 12214 34.800 165.689
Throughput 44.9941 MB/sec 4 clients 4 procs max_latency=165.722 ms
XFS seems to exhibit similar latency improvements as ext2:
3.8.0-rc3:
WriteX 125739 0.028 104.343
ReadX 399070 0.005 4.115
Flush 17851 25.004 131.390
Throughput 66.0024 MB/sec 4 clients 4 procs max_latency=131.406 ms
3.8.0-rc3 + patches:
WriteX 123529 0.028 6.299
ReadX 392434 0.005 4.287
Flush 17549 25.120 188.687
Throughput 64.9113 MB/sec 4 clients 4 procs max_latency=188.704 ms
...and btrfs, just to round things out, also shows some latency
decreases:
3.8.0-rc3:
WriteX 67122 0.083 82.355
ReadX 212719 0.005 2.828
Flush 9547 47.561 147.418
Throughput 35.3391 MB/sec 4 clients 4 procs max_latency=147.433 ms
3.8.0-rc3 + patches:
WriteX 64898 0.101 71.631
ReadX 206673 0.005 7.123
Flush 9190 47.963 219.034
Throughput 34.0795 MB/sec 4 clients 4 procs max_latency=219.044 ms
Before this patchset, all filesystems would block, regardless of whether
or not it was necessary. ext3 would wait, but still generate occasional
checksum errors. The network filesystems were left to do their own
thing, so they'd wait too.
After this patchset, all the disk filesystems except ext3 and btrfs will
wait only if the hardware requires it. ext3 (if necessary) snapshots
pages instead of blocking, and btrfs provides its own bdi so the mm will
never wait. Network filesystems haven't been touched, so either they
provide their own wait code, or they don't block at all. The blocking
behavior is back to what it was before 3.0 if you don't have a disk
requiring stable page writes.
This patchset has been tested on 3.8.0-rc3 on x64 with ext3, ext4, and
xfs. I've spot-checked 3.8.0-rc4 and seem to be getting the same
results as -rc3.
[1] The alternative fixes to ext3 include fixing the locking order and
page bit handling like we did for ext4 (but then why not just use
ext4?), or setting PG_writeback so early that ext3 becomes extremely
slow. I tried that, but the number of write()s I could initiate dropped
by nearly an order of magnitude. That was a bit much even for the
author of the stable page series! :)
This patch:
Creates a per-backing-device flag that tracks whether or not pages must
be held immutable during writeout. Eventually it will be used to waive
wait_for_page_writeback() if nothing requires stable pages.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Artem Bityutskiy <dedekind1@gmail.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Eric Van Hensbergen <ericvh@gmail.com>
Cc: Ron Minnich <rminnich@sandia.gov>
Cc: Latchesar Ionkov <lucho@ionkov.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull async changes from Tejun Heo:
"These are followups for the earlier deadlock issue involving async
ending up waiting for itself through block requesting module[1]. The
following changes are made by these commits.
- Instead of requesting default elevator on each request_queue init,
block now requests it once early during boot.
- Kmod triggers warning if invoked from an async worker.
- Async synchronization implementation has been reimplemented. It's
a lot simpler now."
* 'for-3.9-async' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
async: initialise list heads to fix crash
async: replace list of active domains with global list of pending items
async: keep pending tasks on async_domain and remove async_pending
async: use ULLONG_MAX for infinity cookie value
async: bring sanity to the use of words domain and running
async, kmod: warn on synchronous request_module() from async workers
block: don't request module during elevator init
init, block: try to load default elevator module early during boot
Pull scheduler changes from Ingo Molnar:
"Main changes:
- scheduler side full-dynticks (user-space execution is undisturbed
and receives no timer IRQs) preparation changes that convert the
cputime accounting code to be full-dynticks ready, from Frederic
Weisbecker.
- Initial sched.h split-up changes, by Clark Williams
- select_idle_sibling() performance improvement by Mike Galbraith:
" 1 tbench pair (worst case) in a 10 core + SMT package:
pre 15.22 MB/sec 1 procs
post 252.01 MB/sec 1 procs "
- sched_rr_get_interval() ABI fix/change. We think this detail is not
used by apps (so it's not an ABI in practice), but lets keep it
under observation.
- misc RT scheduling cleanups, optimizations"
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
sched/rt: Add <linux/sched/rt.h> header to <linux/init_task.h>
cputime: Remove irqsave from seqlock readers
sched, powerpc: Fix sched.h split-up build failure
cputime: Restore CPU_ACCOUNTING config defaults for PPC64
sched/rt: Move rt specific bits into new header file
sched/rt: Add a tuning knob to allow changing SCHED_RR timeslice
sched: Move sched.h sysctl bits into separate header
sched: Fix signedness bug in yield_to()
sched: Fix select_idle_sibling() bouncing cow syndrome
sched/rt: Further simplify pick_rt_task()
sched/rt: Do not account zero delta_exec in update_curr_rt()
cputime: Safely read cputime of full dynticks CPUs
kvm: Prepare to add generic guest entry/exit callbacks
cputime: Use accessors to read task cputime stats
cputime: Allow dynamic switch between tick/virtual based cputime accounting
cputime: Generic on-demand virtual cputime accounting
cputime: Move default nsecs_to_cputime() to jiffies based cputime file
cputime: Librarize per nsecs resolution cputime definitions
cputime: Avoid multiplication overflow on utime scaling
context_tracking: Export context state for generic vtime
...
Fix up conflict in kernel/context_tracking.c due to comment additions.
Using wait_for_completion() for waiting for a IO request to be executed
results in wrong iowait time accounting. For example, a system having
the only task doing write() and fdatasync() on a block device can be
reported being idle instead of iowaiting as it should because
blkdev_issue_flush() calls wait_for_completion() which in turn calls
schedule() that does not increment the iowait proc counter and thus does
not turn on iowait time accounting.
The patch makes block layer use wait_for_completion_io() instead of
wait_for_completion() where appropriate to account iowait time
correctly.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Move the sysctl-related bits from include/linux/sched.h into
a new file: include/linux/sched/sysctl.h. Then update source
files requiring access to those bits by including the new
header file.
Signed-off-by: Clark Williams <williams@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20130207094659.06dced96@riff.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Block layer allows selecting an elevator which is built as a module to
be selected as system default via kernel param "elevator=". This is
achieved by automatically invoking request_module() whenever a new
block device is initialized and the elevator is not available.
This led to an interesting deadlock problem involving async and module
init. Block device probing running off an async job invokes
request_module(). While the module is being loaded, it performs
async_synchronize_full() which ends up waiting for the async job which
is already waiting for request_module() to finish, leading to
deadlock.
Invoking request_module() from deep in block device init path is
already nasty in itself. It seems best to avoid these situations from
the beginning by moving on-demand module loading out of block init
path.
The previous patch made sure that the default elevator module is
loaded early during boot if available. This patch removes on-demand
loading of the default elevator from elevator init path. As the
module would have been loaded during boot, userland-visible behavior
difference should be minimal.
For more details, please refer to the following thread.
http://thread.gmane.org/gmane.linux.kernel/1420814
v2: The bool parameter was named @request_module which conflicted with
request_module(). This built okay w/ CONFIG_MODULES because
request_module() was defined as a macro. W/o CONFIG_MODULES, it
causes build breakage. Rename the parameter to @try_loading.
Reported by Fengguang.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Alex Riesen <raa.lkml@gmail.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
This patch adds default module loading and uses it to load the default
block elevator. During boot, it's called right after initramfs or
initrd is made available and right before control is passed to
userland. This ensures that as long as the modules are available in
the usual places in initramfs, initrd or the root filesystem, the
default modules are loaded as soon as possible.
This will replace the on-demand elevator module loading from elevator
init path.
v2: Fixed build breakage when !CONFIG_BLOCK. Reported by kbuild test
robot.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Alex Riesen <raa.lkml@gmail.com>
Cc: Fengguang We <fengguang.wu@intel.com>
bio_{front|back}_merge tracepoints report a bio merging into an
existing request but didn't specify which request the bio is being
merged into. Add @req to it. This makes it impossible to share the
event template with block_bio_queue - split it out.
@req isn't used or exported to userland at this point and there is no
userland visible behavior change. Later changes will make use of the
extra parameter.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
bio completion didn't kick block_bio_complete TP. Only dm was
explicitly triggering the TP on IO completion. This makes
block_bio_complete TP useless for tracers which want to know about
bios, and all other bio based drivers skip generating blktrace
completion events.
This patch makes all bio completions via bio_endio() generate
block_bio_complete TP.
* Explicit trace_block_bio_complete() invocation removed from dm and
the trace point is unexported.
* @rq dropped from trace_block_bio_complete(). bios may fly around
w/o queue associated. Verifying and accessing the assocaited queue
belongs to TP probes.
* blktrace now gets both request and bio completions. Make it ignore
bio completions if request completion path is happening.
This makes all bio based drivers generate blktrace completion events
properly and makes the block_bio_complete TP actually useful.
v2: With this change, block_bio_complete TP could be invoked on sg
commands which have bio's with %NULL bi_bdev. Update TP
assignment code to check whether bio->bi_bdev is %NULL before
dereferencing.
Signed-off-by: Tejun Heo <tj@kernel.org>
Original-patch-by: Namhyung Kim <namhyung@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: dm-devel@redhat.com
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Tejun writes:
Hello, Jens.
Please consider pulling from the following branch to receive cfq blkcg
hierarchy support. The branch is based on top of v3.8-rc2.
git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git blkcg-cfq-hierarchy
The patchset was reviewd in the following thread.
http://thread.gmane.org/gmane.linux.kernel.cgroups/5571
In commit 975927b942c932,it add blk_rq_pos to sort rq when flushing.
Although this commit was used for the situation which blk_plug handled
multi devices on the same time like md device.
I think there must be some situations like this but only single
device.
So remove the should_sort judgement.
Because the parameter should_sort is only for this purpose,it can delete
should_sort from blk_plug.
CC: Shaohua Li <shli@kernel.org>
Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Switch elevator to use the new hashtable implementation. This reduces the
amount of generic unrelated code in the elevator.
This also removes the dymanic allocation of the hash table. The size of the table is
constant so there's no point in paying the price of an extra dereference when accessing
it.
This patch depends on d9b482c ("hashtable: introduce a small and naive
hashtable") which was merged in v3.6.
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Unfortunately, at this point, there's no way to make the existing
statistics hierarchical without creating nasty surprises for the
existing users. Just create recursive counterpart of the existing
stats.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
To support hierarchical stats, it's necessary to remember stats from
dead children. Add cfqg->dead_stats and make a dying cfqg transfer
its stats to the parent's dead-stats.
The transfer happens form ->pd_offline_fn() and it is possible that
there are some residual IOs completing afterwards. Currently, we lose
these stats. Given that cgroup removal isn't a very high frequency
operation and the amount of residual IOs on offline are likely to be
nil or small, this shouldn't be a big deal and the complexity needed
to handle residual IOs - another callback and rather elaborate
synchronization to reach and lock the matching q - doesn't seem
justified.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Separate out cfqg_stats_reset() which takes struct cfqg_stats * from
cfq_pd_reset_stats() and move the latter to where other pd methods are
defined. cfqg_stats_reset() will be used to implement hierarchical
stats.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Instead of holding blkcg->lock while walking ->blkg_list and executing
prfill(), RCU walk ->blkg_list and hold the blkg's queue lock while
executing prfill(). This makes prfill() implementations easier as
stats are mostly protected by queue lock.
This will be used to implement hierarchical stats.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
RCU free request_queue so that blkcg_gq->q can be dereferenced under
RCU lock. This will be used to implement hierarchical stats.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Implement blkg_[rw]stat_recursive_sum() and blkg_[rw]stat_merge().
The former two collect the [rw]stats designated by the target policy
data and offset from the pd's subtree. The latter two add one
[rw]stat to another.
Note that the recursive sum functions require the queue lock to be
held on entry to make blkg online test reliable. This is necessary to
properly handle stats of a dying blkg.
These will be used to implement hierarchical stats.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Hierarchical stats for cfq-iosched will need __blkg_prfill_rwstat().
Export it.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Rename blkg_rwstat_sum() to blkg_rwstat_total(). sum will be used for
summing up stats from multiple blkgs.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Add two blkcg_policy methods, ->online_pd_fn() and ->offline_pd_fn(),
which are invoked as the policy_data gets activated and deactivated
while holding both blkcg and q locks.
Also, add blkcg_gq->online bool, which is set and cleared as the
blkcg_gq gets activated and deactivated. This flag also is toggled
while holding both blkcg and q locks.
These will be used to implement hierarchical stats.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Add pd->plid so that the policy a pd belongs to can be identified
easily. This will be used to implement hierarchical blkg_[rw]stats.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
With the previous two patches, all cfqg scheduling decisions are based
on vfraction and ready for hierarchy support. The only thing which
keeps the behavior flat is cfqg_flat_parent() which makes vfraction
calculation consider all non-root cfqgs children of the root cfqg.
Replace it with cfqg_parent() which returns the real parent. This
enables full blkcg hierarchy support for cfq-iosched. For example,
consider the following hierarchy.
root
/ \
A:500 B:250
/ \
AA:500 AB:1000
For simplicity, let's say all the leaf nodes have active tasks and are
on service tree. For each leaf node, vfraction would be
AA: (500 / 1500) * (500 / 750) =~ 0.2222
AB: (1000 / 1500) * (500 / 750) =~ 0.4444
B: (250 / 750) =~ 0.3333
and vdisktime will be distributed accordingly. For more detail,
please refer to Documentation/block/cfq-iosched.txt.
v2: cfq-iosched.txt updated to describe group scheduling as suggested
by Vivek.
v3: blkio-controller.txt updated.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
cfq_group_slice() calculates slice by taking a fraction of
cfq_target_latency according to the ratio of cfqg->weight against
service_tree->total_weight. This currently works only because all
cfqgs are treated to be at the same level.
To prepare for proper hierarchy support, convert cfq_group_slice() to
base the calculation on cfqg->vfraction. As cfqg->vfraction is always
a fraction of 1 and represents the fraction allocated to the cfqg with
hierarchy considered, the slice can be simply calculated by
multiplying cfqg->vfraction to cfq_target_latency (with fixed point
shift factored in).
As vfraction calculation currently treats all non-root cfqgs as
children of the root cfqg, this patch doesn't introduce noticeable
behavior difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Currently, cfqg charges are scaled directly according to cfqg->weight.
Regardless of the number of active cfqgs or the amount of active
weights, a given weight value always scales charge the same way. This
works fine as long as all cfqgs are treated equally regardless of
their positions in the hierarchy, which is what cfq currently
implements. It can't work in hierarchical settings because the
interpretation of a given weight value depends on where the weight is
located in the hierarchy.
This patch reimplements cfqg charge scaling so that it can be used to
support hierarchy properly. The scheme is fairly simple and
light-weight.
* When a cfqg is added to the service tree, v(disktime)weight is
calculated. It walks up the tree to root calculating the fraction
it has in the hierarchy. At each level, the fraction can be
calculated as
cfqg->weight / parent->level_weight
By compounding these, the global fraction of vdisktime the cfqg has
claim to - vfraction - can be determined.
* When the cfqg needs to be charged, the charge is scaled inversely
proportionally to the vfraction.
The new scaling scheme uses the same CFQ_SERVICE_SHIFT for fixed point
representation as before; however, the smallest scaling factor is now
1 (ie. 1 << CFQ_SERVICE_SHIFT). This is different from before where 1
was for CFQ_WEIGHT_DEFAULT and higher weight would result in smaller
scaling factor.
While this shifts the global scale of vdisktime a bit, it doesn't
change the relative relationships among cfqgs and the scheduling
result isn't different.
cfq_group_notify_queue_add uses fixed CFQ_IDLE_DELAY when appending
new cfqg to the service tree. The specific value of CFQ_IDLE_DELAY
didn't have any relevance to vdisktime before and is unlikely to cause
any visible behavior difference now especially as the scale shift
isn't that large.
As the new scheme now makes proper distinction between cfqg->weight
and ->leaf_weight, reverse the weight aliasing for root cfqgs. For
root, both weights are now mapped to ->leaf_weight instead of the
other way around.
Because we're still using cfqg_flat_parent(), this patch shouldn't
change the scheduling behavior in any noticeable way.
v2: Beefed up comments on vfraction as requested by Vivek.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
To prepare for blkcg hierarchy support, add cfqg->nr_active and
->children_weight. cfqg->nr_active counts the number of active cfqgs
at the cfqg's level and ->children_weight is sum of weights of those
cfqgs. The level covers itself (cfqg->leaf_weight) and immediate
children.
The two values are updated when a cfqg enters and leaves the group
service tree. Unless the hierarchy is very deep, the added overhead
should be negligible.
Currently, the parent is determined using cfqg_flat_parent() which
makes the root cfqg the parent of all other cfqgs. This is to make
the transition to hierarchy-aware scheduling gradual. Scheduling
logic will be converted to use cfqg->children_weight without actually
changing the behavior. When everything is ready,
blkcg_weight_parent() will be replaced with proper parent function.
This patch doesn't introduce any behavior chagne.
v2: s/cfqg->level_weight/cfqg->children_weight/ as per Vivek.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
cfq blkcg is about to grow proper hierarchy handling, where a child
blkg's weight would nest inside the parent's. This makes tasks in a
blkg to compete against both tasks in the sibling blkgs and the tasks
of child blkgs.
We're gonna use the existing weight as the group weight which decides
the blkg's weight against its siblings. This patch introduces a new
weight - leaf_weight - which decides the weight of a blkg against the
child blkgs.
It's named leaf_weight because another way to look at it is that each
internal blkg nodes have a hidden child leaf node which contains all
its tasks and leaf_weight is the weight of the leaf node and handled
the same as the weight of the child blkgs.
This patch only adds leaf_weight fields and exposes it to userland.
The new weight isn't actually used anywhere yet. Note that
cfq-iosched currently offcially supports only single level hierarchy
and root blkgs compete with the first level blkgs - ie. root weight is
basically being used as leaf_weight. For root blkgs, the two weights
are kept in sync for backward compatibility.
v2: cfqd->root_group->leaf_weight initialization was missing from
cfq_init_queue() causing divide by zero when
!CONFIG_CFQ_GROUP_SCHED. Fix it. Reported by Fengguang.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Currently a child blkg (blkcg_gq) can be created even if its parent
doesn't exist. ie. Given a blkg, it's not guaranteed that its
ancestors will exist. This makes it difficult to implement proper
hierarchy support for blkcg policies.
Always create blkgs recursively and make a child blkg hold a reference
to its parent. blkg->parent is added so that finding the parent is
easy. blkcg_parent() is also added in the process.
This change can be visible to userland. e.g. while issuing IO in a
nested cgroup didn't affect the ancestors at all, now it will
initialize all ancestor blkgs and zero stats for the request_queue
will always appear on them. While this is userland visible, this
shouldn't cause any functional difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
* Rename out_* labels to err_*.
* Do ERR_PTR() conversion once in the error return path.
This patch is cosmetic and to prepare for the hierarchy support.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Reorganize such that
* __blkg_lookup() takes bool param @update_hint to determine whether
to update hint.
* __blkg_lookup_create() no longer performs lookup before trying to
create. Renamed to blkg_create().
* blkg_lookup_create() now performs lookup and then invokes
blkg_create() if lookup fails.
* root_blkg creation in blkcg_activate_policy() updated accordingly.
Note that blkcg_activate_policy() no longer updates lookup hint if
root_blkg already exists.
Except for the last lookup hint bit which is immaterial, this is pure
reorganization and doesn't introduce any visible behavior change.
This is to prepare for proper hierarchy support.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
blkg_alloc() was mistakenly checking blkcg_policy_enabled() twice.
The latter test should have been on whether pol->pd_init_fn() exists.
This doesn't cause actual problems because both blkcg policies
implement pol->pd_init_fn(). Fix it.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Currently we attach a character "S" or "A" to the cfqq<pid>, to represent
whether queues is sync or async. Add one more character "N" to represent
whether it is sync-noidle queue or sync queue. So now three different
type of queues will look as follows.
cfq1234S --> sync queus
cfq1234SN --> sync noidle queue
cfq1234A --> Async queue
Previously S/A classification was being printed only if group scheduling
was enabled. This patch also makes sure that this classification is
displayed even if group idling is disabled.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Use of local varibale "n" seems to be unnecessary. Remove it. This brings
it inline with function __cfq_group_st_add(), which is also doing the
similar operation of adding a group to a rb tree.
No functionality change here.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
choose_service_tree() selects/sets both wl_class and wl_type. Rename it to
choose_wl_class_and_type() to make it very clear.
cfq_choose_wl() only selects and sets wl_type. It is easy to confuse
it with choose_st(). So rename it to cfq_choose_wl_type() to make
it clear what does it do.
Just renaming. No functionality change.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
At quite a few places we use the keyword "service_tree". At some places,
especially local variables, I have abbreviated it to "st".
Also at couple of places moved binary operator "+" from beginning of line
to end of previous line, as per Tejun's feedback.
v2:
Reverted most of the service tree name change based on Jeff Moyer's feedback.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Some more renaming. Again making the code uniform w.r.t use of
wl_class/class to represent IO class (RT, BE, IDLE) and using
wl_type/type to represent subclass (SYNC, SYNC-IDLE, ASYNC).
At places this patch shortens the string "workload" to "wl".
Renamed "saved_workload" to "saved_wl_type". Renamed
"saved_serving_class" to "saved_wl_class".
For uniformity with "saved_wl_*" variables, renamed "serving_class"
to "serving_wl_class" and renamed "serving_type" to "serving_wl_type".
Again, just trying to improve upon code uniformity and improve
readability. No functional change.
v2:
- Restored the usage of keyword "service" based on Jeff Moyer's feedback.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Currently CFQ has three IO classes, RT, BE and IDLE. At many a places we
are calling workloads belonging to these classes as "prio". This gets
very confusing as one starts to associate it with ioprio.
So this patch just does bunch of renaming so that reading code becomes
easier. All reference to RT, BE and IDLE workload are done using keyword
"class" and all references to subclass, SYNC, SYNC-IDLE, ASYNC are made
using keyword "type".
This makes me feel much better while I am reading the code. There is no
functionality change due to this patch.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Remove a race condition which causes a warning in disk_clear_events. This
is a race between disk_clear_events() and disk_flush_events().
ev->clearing will be altered by disk_flush_events() even though we are
blocking event checking through disk_flush_events(). If this happens
after ev->clearing was cleared for disk_clear_events(), this can cause the
WARN_ON_ONCE() in that function to be triggered.
This change also has disk_clear_events() not go through a workqueue.
Since we have to wait for the work to complete, we should just call the
function directly. Also, since this work cannot be put on a freezable
workqueue, it will have to contend with increased demand, so calling the
function directly avoids this.
[akpm@linux-foundation.org: fix spello in comment]
Signed-off-by: Derek Basehore <dbasehore@chromium.org>
Cc: Mandeep Singh Baines <msb@chromium.org>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In disk_clear_events, do not put work on system_nrt_freezable_wq.
Instead, put it on system_nrt_wq.
There is a race between probing a usb and suspending the device. Since
probing a usb calls disk_clear_events, which puts work on a frozen
workqueue, probing cannot finish after the workqueue is frozen. However,
suspending cannot finish until the usb probe is finished, so we get a
deadlock, causing the system to reboot.
The way to reproduce this bug is to wake up from suspend with a usb
storage device plugged in, or plugging in a usb storage device right
before suspend. The window of time is on the order of time it takes to
probe the usb device. As long as the workqueues are frozen before the
call to add_disk within sd_probe_async finishes, there will be a deadlock
(which calls blkdev_get, sd_open, check_disk_change, then
disk_clear_events). This is not difficult to reproduce after figuring out
the timings.
[akpm@linux-foundation.org: fix up comment]
Signed-off-by: Derek Basehore <dbasehore@chromium.org>
Reviewed-by: Mandeep Singh Baines <msb@chromium.org>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Merge misc patches from Andrew Morton:
"Incoming:
- lots of misc stuff
- backlight tree updates
- lib/ updates
- Oleg's percpu-rwsem changes
- checkpatch
- rtc
- aoe
- more checkpoint/restart support
I still have a pile of MM stuff pending - Pekka should be merging
later today after which that is good to go. A number of other things
are twiddling thumbs awaiting maintainer merges."
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (180 commits)
scatterlist: don't BUG when we can trivially return a proper error.
docs: update documentation about /proc/<pid>/fdinfo/<fd> fanotify output
fs, fanotify: add @mflags field to fanotify output
docs: add documentation about /proc/<pid>/fdinfo/<fd> output
fs, notify: add procfs fdinfo helper
fs, exportfs: add exportfs_encode_inode_fh() helper
fs, exportfs: escape nil dereference if no s_export_op present
fs, epoll: add procfs fdinfo helper
fs, eventfd: add procfs fdinfo helper
procfs: add ability to plug in auxiliary fdinfo providers
tools/testing/selftests/kcmp/kcmp_test.c: print reason for failure in kcmp_test
breakpoint selftests: print failure status instead of cause make error
kcmp selftests: print fail status instead of cause make error
kcmp selftests: make run_tests fix
mem-hotplug selftests: print failure status instead of cause make error
cpu-hotplug selftests: print failure status instead of cause make error
mqueue selftests: print failure status instead of cause make error
vm selftests: print failure status instead of cause make error
ubifs: use prandom_bytes
mtd: nandsim: use prandom_bytes
...
Pull block driver update from Jens Axboe:
"Now that the core bits are in, here are the driver bits for 3.8. The
branch contains:
- A huge pile of drbd bits that were dumped from the 3.7 merge
window. Following that, it was both made perfectly clear that
there is going to be no more over-the-wall pulls and how the
situation on individual pulls can be improved.
- A few cleanups from Akinobu Mita for drbd and cciss.
- Queue improvement for loop from Lukas. This grew into adding a
generic interface for waiting/checking an even with a specific
lock, allowing this to be pulled out of md and now loop and drbd is
also using it.
- A few fixes for xen back/front block driver from Roger Pau Monne.
- Partition improvements from Stephen Warren, allowing partiion UUID
to be used as an identifier."
* 'for-3.8/drivers' of git://git.kernel.dk/linux-block: (609 commits)
drbd: update Kconfig to match current dependencies
drbd: Fix drbdsetup wait-connect, wait-sync etc... commands
drbd: close race between drbd_set_role and drbd_connect
drbd: respect no-md-barriers setting also when changed online via disk-options
drbd: Remove obsolete check
drbd: fixup after wait_even_lock_irq() addition to generic code
loop: Limit the number of requests in the bio list
wait: add wait_event_lock_irq() interface
xen-blkfront: free allocated page
xen-blkback: move free persistent grants code
block: partition: msdos: provide UUIDs for partitions
init: reduce PARTUUID min length to 1 from 36
block: store partition_meta_info.uuid as a string
cciss: use check_signature()
cciss: cleanup bitops usage
drbd: use copy_highpage
drbd: if the replication link breaks during handshake, keep retrying
drbd: check return of kmalloc in receive_uuids
drbd: Broadcast sync progress no more often than once per second
drbd: don't try to clear bits once the disk has failed
...
Pull block layer core updates from Jens Axboe:
"Here are the core block IO bits for 3.8. The branch contains:
- The final version of the surprise device removal fixups from Bart.
- Don't hide EFI partitions under advanced partition types. It's
fairly wide spread these days. This is especially dangerous for
systems that have both msdos and efi partition tables, where you
want to keep them in sync.
- Cleanup of using -1 instead of the proper NUMA_NO_NODE
- Export control of bdi flusher thread CPU mask and default to using
the home node (if known) from Jeff.
- Export unplug tracepoint for MD.
- Core improvements from Shaohua. Reinstate the recursive merge, as
the original bug has been fixed. Add plugging for discard and also
fix a problem handling non pow-of-2 discard limits.
There's a trivial merge in block/blk-exec.c due to a fix that went
into 3.7-rc at a later point than -rc4 where this is based."
* 'for-3.8/core' of git://git.kernel.dk/linux-block:
block: export block_unplug tracepoint
block: add plug for blkdev_issue_discard
block: discard granularity might not be power of 2
deadline: Allow 0ms deadline latency, increase the read speed
partitions: enable EFI/GPT support by default
bsg: Remove unused function bsg_goose_queue()
block: Make blk_cleanup_queue() wait until request_fn finished
block: Avoid scheduling delayed work on a dead queue
block: Avoid that request_fn is invoked on a dead queue
block: Let blk_drain_queue() caller obtain the queue lock
block: Rename queue dead flag
bdi: add a user-tunable cpu_list for the bdi flusher threads
block: use NUMA_NO_NODE instead of -1
block: recursive merge requests
block CFQ: avoid moving request to different queue
Last post of this patch appears lost, so I resend this.
Now discard merge works, add plug for blkdev_issue_discard. This will help
discard request merge especially for raid0 case. In raid0, a big discard
request is split to small requests, and if correct plug is added, such small
requests can be merged in low layer.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In MD raid case, discard granularity might not be power of 2, for example, a
4-disk raid5 has 3*chunk_size discard granularity. Correct the calculation for
such cases.
Reported-by: Neil Brown <neilb@suse.de>
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull cgroup changes from Tejun Heo:
"A lot of activities on cgroup side. The big changes are focused on
making cgroup hierarchy handling saner.
- cgroup_rmdir() had peculiar semantics - it allowed cgroup
destruction to be vetoed by individual controllers and tried to
drain refcnt synchronously. The vetoing never worked properly and
caused good deal of contortions in cgroup. memcg was the last
reamining user. Michal Hocko removed the usage and cgroup_rmdir()
path has been simplified significantly. This was done in a
separate branch so that the memcg people can base further memcg
changes on top.
- The above allowed cleaning up cgroup lifecycle management and
implementation of generic cgroup iterators which are used to
improve hierarchy support.
- cgroup_freezer updated to allow migration in and out of a frozen
cgroup and handle hierarchy. If a cgroup is frozen, all descendant
cgroups are frozen.
- netcls_cgroup and netprio_cgroup updated to handle hierarchy
properly.
- Various fixes and cleanups.
- Two merge commits. One to pull in memcg and rmdir cleanups (needed
to build iterators). The other pulled in cgroup/for-3.7-fixes for
device_cgroup fixes so that further device_cgroup patches can be
stacked on top."
Fixed up a trivial conflict in mm/memcontrol.c as per Tejun (due to
commit bea8c150a7 ("memcg: fix hotplugged memory zone oops") in master
touching code close to commit 2ef37d3fe4 ("memcg: Simplify
mem_cgroup_force_empty_list error handling") in for-3.8)
* 'for-3.8' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (65 commits)
cgroup: update Documentation/cgroups/00-INDEX
cgroup_rm_file: don't delete the uncreated files
cgroup: remove subsystem files when remounting cgroup
cgroup: use cgroup_addrm_files() in cgroup_clear_directory()
cgroup: warn about broken hierarchies only after css_online
cgroup: list_del_init() on removed events
cgroup: fix lockdep warning for event_control
cgroup: move list add after list head initilization
netprio_cgroup: allow nesting and inherit config on cgroup creation
netprio_cgroup: implement netprio[_set]_prio() helpers
netprio_cgroup: use cgroup->id instead of cgroup_netprio_state->prioidx
netprio_cgroup: reimplement priomap expansion
netprio_cgroup: shorten variable names in extend_netdev_table()
netprio_cgroup: simplify write_priomap()
netcls_cgroup: move config inheritance to ->css_online() and remove .broken_hierarchy marking
cgroup: remove obsolete guarantee from cgroup_task_migrate.
cgroup: add cgroup->id
cgroup, cpuset: remove cgroup_subsys->post_clone()
cgroup: s/CGRP_CLONE_CHILDREN/CGRP_CPUSET_CLONE_CHILDREN/
cgroup: rename ->create/post_create/pre_destroy/destroy() to ->css_alloc/online/offline/free()
...
Change a timer compare from after to after-equals, thus allowing
0 timeout and making deadline schedule FIFO.
Signed-off-by: xiaobing tu <xiaobing.tu@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The Kconfig currently enables MSDOS partitions by default because they
are assumed to be essential, but it's necessary to enable "advanced
partition selection" in order to get GPT support. IMO GPT partitions
are becoming common enought to deserve the same treatment MSDOS
partitions get.
(Side note: I got bit by a disk that had MSDOS and GPT partition
tables, but for some reason the MSDOS table was different from the
GPT one. I was stupid enought to disable "advanced partition
selection" in my .config, which disabled GPT partitioning and made
my btrfs pool unbootable because it couldn't find the partitions)
Signed-off-by: Diego Calleja <diegocg@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The function bsg_goose_queue() does not have any in-tree callers,
so let's remove it.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Some request_fn implementations, e.g. scsi_request_fn(), unlock
the queue lock internally. This may result in multiple threads
executing request_fn for the same queue simultaneously. Keep
track of the number of active request_fn calls and make sure that
blk_cleanup_queue() waits until all active request_fn invocations
have finished. A block driver may start cleaning up resources
needed by its request_fn as soon as blk_cleanup_queue() finished,
so blk_cleanup_queue() must wait for all outstanding request_fn
invocations to finish.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reported-by: Chanho Min <chanho.min@lge.com>
Cc: James Bottomley <JBottomley@Parallels.com>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Running a queue must continue after it has been marked dying until
it has been marked dead. So the function blk_run_queue_async() must
not schedule delayed work after blk_cleanup_queue() has marked a queue
dead. Hence add a test for that queue state in blk_run_queue_async()
and make sure that queue_unplugged() invokes that function with the
queue lock held. This avoids that the queue state can change after
it has been tested and before mod_delayed_work() is invoked. Drop
the queue dying test in queue_unplugged() since it is now
superfluous: __blk_run_queue() already tests whether or not the
queue is dead.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
A block driver may start cleaning up resources needed by its
request_fn as soon as blk_cleanup_queue() finished, so request_fn
must not be invoked after draining finished. This is important
when blk_run_queue() is invoked without any requests in progress.
As an example, if blk_drain_queue() and scsi_run_queue() run in
parallel, blk_drain_queue() may have finished all requests after
scsi_run_queue() has taken a SCSI device off the starved list but
before that last function has had a chance to run the queue.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Cc: James Bottomley <JBottomley@Parallels.com>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Chanho Min <chanho.min@lge.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Let the caller of blk_drain_queue() obtain the queue lock to improve
readability of the patch called "Avoid that request_fn is invoked on
a dead queue".
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: James Bottomley <JBottomley@Parallels.com>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Chanho Min <chanho.min@lge.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
QUEUE_FLAG_DEAD is used to indicate that queuing new requests must
stop. After this flag has been set queue draining starts. However,
during the queue draining phase it is still safe to invoke the
queue's request_fn, so QUEUE_FLAG_DYING is a better name for this
flag.
This patch has been generated by running the following command
over the kernel source tree:
git grep -lEw 'blk_queue_dead|QUEUE_FLAG_DEAD' |
xargs sed -i.tmp -e 's/blk_queue_dead/blk_queue_dying/g' \
-e 's/QUEUE_FLAG_DEAD/QUEUE_FLAG_DYING/g'; \
sed -i.tmp -e "s/QUEUE_FLAG_DYING$(printf \\t)*5/QUEUE_FLAG_DYING$(printf \\t)5/g" \
include/linux/blkdev.h; \
sed -i.tmp -e 's/ DEAD/ DYING/g' -e 's/dead queue/a dying queue/' \
-e 's/Dead queue/A dying queue/' block/blk-core.c
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: James Bottomley <JBottomley@Parallels.com>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Chanho Min <chanho.min@lge.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
After we've done __elv_add_request() and __blk_run_queue() in
blk_execute_rq_nowait(), the request might finish and be freed
immediately. Therefore checking if the type is REQ_TYPE_PM_RESUME
isn't safe afterwards, because if it isn't, rq might be gone.
Instead, check beforehand and stash the result in a temporary.
This fixes crashes in blk_execute_rq_nowait() I get occasionally when
running with lots of memory debugging options enabled -- I think this
race is usually harmless because the window for rq to be reallocated
is so small.
Signed-off-by: Roland Dreier <roland@purestorage.com>
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The MSDOS/MBR partition table includes a 32-bit unique ID, often referred
to as the NT disk signature. When combined with a partition number within
the table, this can form a unique ID similar in concept to EFI/GPT's
partition UUID. Constructing and recording this value in struct
partition_meta_info allows MSDOS partitions to be referred to on the
kernel command-line using the following syntax:
root=PARTUUID=0002dd75-01
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Will Drewry <wad@chromium.org>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This will allow other types of UUID to be stored here, aside from true
UUIDs. This also simplifies code that uses this field, since it's usually
constructed from a, used as a, or compared to other, strings.
Note: A simplistic approach here would be to set uuid_str[36]=0 whenever a
/PARTNROFF option was found to be present. However, this modifies the
input string, and causes subsequent calls to devt_from_partuuid() not to
see the /PARTNROFF option, which causes different results. In order to
avoid misleading future maintainers, this parameter is marked const.
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Will Drewry <wad@chromium.org>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Rename cgroup_subsys css lifetime related callbacks to better describe
what their roles are. Also, update documentation.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
In a workload, thread 1 accesses a, a+2, ..., thread 2 accesses a+1, a+3,....
When the requests are flushed to queue, a and a+1 are merged to (a, a+1), a+2
and a+3 too to (a+2, a+3), but (a, a+1) and (a+2, a+3) aren't merged.
If we do recursive merge for such interleave access, some workloads throughput
get improvement. A recent worload I'm checking on is swap, below change
boostes the throughput around 5% ~ 10%.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
request is queued in cfqq->fifo list. Looks it's possible we are moving a
request from one cfqq to another in request merge case. In such case, adjusting
the fifo list order doesn't make sense and is impossible if we don't iterate
the whole fifo list.
My test does hit one case the two cfqq are different, but didn't cause kernel
crash, maybe it's because fifo list isn't used frequently. Anyway, from the
code logic, this is buggy.
I thought we can re-enable the recusive merge logic after this is fixed.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull rmdir updates into for-3.8 so that further callback updates can
be put on top. This pull created a trivial conflict between the
following two commits.
8c7f6edbda ("cgroup: mark subsystems with broken hierarchy support and whine if cgroups are nested for them")
ed95779340 ("cgroup: kill cgroup_subsys->__DEPRECATED_clear_css_refs")
The former added a field to cgroup_subsys and the latter removed one
from it. They happen to be colocated causing the conflict. Keeping
what's added and removing what's removed resolves the conflict.
Signed-off-by: Tejun Heo <tj@kernel.org>
All ->pre_destory() implementations return 0 now, which is the only
allowed return value. Make it return void.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
My workload is a raid5 which had 16 disks. And used our filesystem to
write using direct-io mode.
I used the blktrace to find those message:
8,16 0 6647 2.453665504 2579 M W 7493152 + 8 [md0_raid5]
8,16 0 6648 2.453672411 2579 Q W 7493160 + 8 [md0_raid5]
8,16 0 6649 2.453672606 2579 M W 7493160 + 8 [md0_raid5]
8,16 0 6650 2.453679255 2579 Q W 7493168 + 8 [md0_raid5]
8,16 0 6651 2.453679441 2579 M W 7493168 + 8 [md0_raid5]
8,16 0 6652 2.453685948 2579 Q W 7493176 + 8 [md0_raid5]
8,16 0 6653 2.453686149 2579 M W 7493176 + 8 [md0_raid5]
8,16 0 6654 2.453693074 2579 Q W 7493184 + 8 [md0_raid5]
8,16 0 6655 2.453693254 2579 M W 7493184 + 8 [md0_raid5]
8,16 0 6656 2.453704290 2579 Q W 7493192 + 8 [md0_raid5]
8,16 0 6657 2.453704482 2579 M W 7493192 + 8 [md0_raid5]
8,16 0 6658 2.453715016 2579 Q W 7493200 + 8 [md0_raid5]
8,16 0 6659 2.453715247 2579 M W 7493200 + 8 [md0_raid5]
8,16 0 6660 2.453721730 2579 Q W 7493208 + 8 [md0_raid5]
8,16 0 6661 2.453721974 2579 M W 7493208 + 8 [md0_raid5]
8,16 0 6662 2.453728202 2579 Q W 7493216 + 8 [md0_raid5]
8,16 0 6663 2.453728436 2579 M W 7493216 + 8 [md0_raid5]
8,16 0 6664 2.453734782 2579 Q W 7493224 + 8 [md0_raid5]
8,16 0 6665 2.453735019 2579 M W 7493224 + 8 [md0_raid5]
8,16 0 6666 2.453741401 2579 Q W 7493232 + 8 [md0_raid5]
8,16 0 6667 2.453741632 2579 M W 7493232 + 8 [md0_raid5]
8,16 0 6668 2.453748148 2579 Q W 7493240 + 8 [md0_raid5]
8,16 0 6669 2.453748386 2579 M W 7493240 + 8 [md0_raid5]
8,16 0 6670 2.453851843 2579 I W 7493144 + 104 [md0_raid5]
8,16 0 0 2.453853661 0 m N cfq2579 insert_request
8,16 0 6671 2.453854064 2579 I W 7493120 + 24 [md0_raid5]
8,16 0 0 2.453854439 0 m N cfq2579 insert_request
8,16 0 6672 2.453854793 2579 U N [md0_raid5] 2
8,16 0 0 2.453855513 0 m N cfq2579 Not idling.st->count:1
8,16 0 0 2.453855927 0 m N cfq2579 dispatch_insert
8,16 0 0 2.453861771 0 m N cfq2579 dispatched a request
8,16 0 0 2.453862248 0 m N cfq2579 activate rq,drv=1
8,16 0 6673 2.453862332 2579 D W 7493120 + 24 [md0_raid5]
8,16 0 0 2.453865957 0 m N cfq2579 Not idling.st->count:1
8,16 0 0 2.453866269 0 m N cfq2579 dispatch_insert
8,16 0 0 2.453866707 0 m N cfq2579 dispatched a request
8,16 0 0 2.453867061 0 m N cfq2579 activate rq,drv=2
8,16 0 6674 2.453867145 2579 D W 7493144 + 104 [md0_raid5]
8,16 0 6675 2.454147608 0 C W 7493120 + 24 [0]
8,16 0 0 2.454149357 0 m N cfq2579 complete rqnoidle 0
8,16 0 6676 2.454791505 0 C W 7493144 + 104 [0]
8,16 0 0 2.454794803 0 m N cfq2579 complete rqnoidle 0
8,16 0 0 2.454795160 0 m N cfq schedule dispatch
From above messages,we can find rq[W 7493144 + 104] and rq[W
7493120 + 24] do not merge.
Because the bio order is:
8,16 0 6638 2.453619407 2579 Q W 7493144 + 8 [md0_raid5]
8,16 0 6639 2.453620460 2579 G W 7493144 + 8 [md0_raid5]
8,16 0 6640 2.453639311 2579 Q W 7493120 + 8 [md0_raid5]
8,16 0 6641 2.453639842 2579 G W 7493120 + 8 [md0_raid5]
The bio(7493144) first and bio(7493120) later.So the subsequent
bios will be divided into two parts.
When flushing plug-list,because elv_attempt_insert_merge only support
backmerge,not supporting frontmerge.
So rq[7493120 + 24] can't merge with rq[7493144 + 104].
From my test,i found those situation can count 25% in our system.
Using this patch, there is no this situation.
Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>
CC:Shaohua Li <shli@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This config item has not carried much meaning for a while now and is
almost always enabled by default. As agreed during the Linux kernel
summit, remove it.
CC: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
__blk_queue_next_rl() finds next request list based on blkg_list
while skipping root_blkg in the list.
OTOH, root_rl is special as it may exist even without root_blkg.
Though the later part of the function handles such a case correctly,
exiting early is good for readability of the code.
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Cc: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull block IO update from Jens Axboe:
"Core block IO bits for 3.7. Not a huge round this time, it contains:
- First series from Kent cleaning up and generalizing bio allocation
and freeing.
- WRITE_SAME support from Martin.
- Mikulas patches to prevent O_DIRECT crashes when someone changes
the block size of a device.
- Make bio_split() work on data-less bio's (like trim/discards).
- A few other minor fixups."
Fixed up silent semantic mis-merge as per Mikulas Patocka and Andrew
Morton. It is due to the VM no longer using a prio-tree (see commit
6b2dbba8b6: "mm: replace vma prio_tree with an interval tree").
So make set_blocksize() use mapping_mapped() instead of open-coding the
internal VM knowledge that has changed.
* 'for-3.7/core' of git://git.kernel.dk/linux-block: (26 commits)
block: makes bio_split support bio without data
scatterlist: refactor the sg_nents
scatterlist: add sg_nents
fs: fix include/percpu-rwsem.h export error
percpu-rw-semaphore: fix documentation typos
fs/block_dev.c:1644:5: sparse: symbol 'blkdev_mmap' was not declared
blockdev: turn a rw semaphore into a percpu rw semaphore
Fix a crash when block device is read and block size is changed at the same time
block: fix request_queue->flags initialization
block: lift the initial queue bypass mode on blk_register_queue() instead of blk_init_allocated_queue()
block: ioctl to zero block ranges
block: Make blkdev_issue_zeroout use WRITE SAME
block: Implement support for WRITE SAME
block: Consolidate command flag and queue limit checks for merges
block: Clean up special command handling logic
block/blk-tag.c: Remove useless kfree
block: remove the duplicated setting for congestion_threshold
block: reject invalid queue attribute values
block: Add bio_clone_bioset(), bio_clone_kmalloc()
block: Consolidate bio_alloc_bioset(), bio_kmalloc()
...
Pull cgroup hierarchy update from Tejun Heo:
"Currently, different cgroup subsystems handle nested cgroups
completely differently. There's no consistency among subsystems and
the behaviors often are outright broken.
People at least seem to agree that the broken hierarhcy behaviors need
to be weeded out if any progress is gonna be made on this front and
that the fallouts from deprecating the broken behaviors should be
acceptable especially given that the current behaviors don't make much
sense when nested.
This patch makes cgroup emit warning messages if cgroups for
subsystems with broken hierarchy behavior are nested to prepare for
fixing them in the future. This was put in a separate branch because
more related changes were expected (didn't make it this round) and the
memory cgroup wanted to pull in this and make changes on top."
* 'for-3.7-hierarchy' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup: mark subsystems with broken hierarchy support and whine if cgroups are nested for them
Pull workqueue changes from Tejun Heo:
"This is workqueue updates for v3.7-rc1. A lot of activities this
round including considerable API and behavior cleanups.
* delayed_work combines a timer and a work item. The handling of the
timer part has always been a bit clunky leading to confusing
cancelation API with weird corner-case behaviors. delayed_work is
updated to use new IRQ safe timer and cancelation now works as
expected.
* Another deficiency of delayed_work was lack of the counterpart of
mod_timer() which led to cancel+queue combinations or open-coded
timer+work usages. mod_delayed_work[_on]() are added.
These two delayed_work changes make delayed_work provide interface
and behave like timer which is executed with process context.
* A work item could be executed concurrently on multiple CPUs, which
is rather unintuitive and made flush_work() behavior confusing and
half-broken under certain circumstances. This problem doesn't
exist for non-reentrant workqueues. While non-reentrancy check
isn't free, the overhead is incurred only when a work item bounces
across different CPUs and even in simulated pathological scenario
the overhead isn't too high.
All workqueues are made non-reentrant. This removes the
distinction between flush_[delayed_]work() and
flush_[delayed_]_work_sync(). The former is now as strong as the
latter and the specified work item is guaranteed to have finished
execution of any previous queueing on return.
* In addition to the various bug fixes, Lai redid and simplified CPU
hotplug handling significantly.
* Joonsoo introduced system_highpri_wq and used it during CPU
hotplug.
There are two merge commits - one to pull in IRQ safe timer from
tip/timers/core and the other to pull in CPU hotplug fixes from
wq/for-3.6-fixes as Lai's hotplug restructuring depended on them."
Fixed a number of trivial conflicts, but the more interesting conflicts
were silent ones where the deprecated interfaces had been used by new
code in the merge window, and thus didn't cause any real data conflicts.
Tejun pointed out a few of them, I fixed a couple more.
* 'for-3.7' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: (46 commits)
workqueue: remove spurious WARN_ON_ONCE(in_irq()) from try_to_grab_pending()
workqueue: use cwq_set_max_active() helper for workqueue_set_max_active()
workqueue: introduce cwq_set_max_active() helper for thaw_workqueues()
workqueue: remove @delayed from cwq_dec_nr_in_flight()
workqueue: fix possible stall on try_to_grab_pending() of a delayed work item
workqueue: use hotcpu_notifier() for workqueue_cpu_down_callback()
workqueue: use __cpuinit instead of __devinit for cpu callbacks
workqueue: rename manager_mutex to assoc_mutex
workqueue: WORKER_REBIND is no longer necessary for idle rebinding
workqueue: WORKER_REBIND is no longer necessary for busy rebinding
workqueue: reimplement idle worker rebinding
workqueue: deprecate __cancel_delayed_work()
workqueue: reimplement cancel_delayed_work() using try_to_grab_pending()
workqueue: use mod_delayed_work() instead of __cancel + queue
workqueue: use irqsafe timer for delayed_work
workqueue: clean up delayed_work initializers and add missing one
workqueue: make deferrable delayed_work initializer names consistent
workqueue: cosmetic whitespace updates for macro definitions
workqueue: deprecate system_nrt[_freezable]_wq
workqueue: deprecate flush[_delayed]_work_sync()
...
In some usage scenarios it is desireable to work with disk images or
virtualized DASD devices. One problem that prevents such applications
is the partition detection in ibm.c. Currently it works only for
devices that support the BIODASDINFO2 ioctl, in other words, it only
works for devices that belong to the DASD device driver.
The information gained from the BIODASDINFO2 ioctl is only for a small
set of legacy cases abolutely necessary. All current VOL1, LNX1 and
CMS1 type of disk labels can be interpreted correctly without this
information, as long as the generic HDIO_GETGEO ioctl works and
provides a correct disk geometry.
This patch makes the ibm.c partition detection as independent as
possible from the BIODASDINFO2 ioctl. Only the following two cases are
still restricted to real DASDs:
- An FBA DASD, or LDL formatted ECKD DASD without any disk label.
- An old style LNX1 label (without large volume support) on a disk
with inconsistent device geometry.
Signed-off-by: Stefan Weinhuber <wein@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
A queue newly allocated with blk_alloc_queue_node() has only
QUEUE_FLAG_BYPASS set. For request-based drivers,
blk_init_allocated_queue() is called and q->queue_flags is overwritten
with QUEUE_FLAG_DEFAULT which doesn't include BYPASS even though the
initial bypass is still in effect.
In blk_init_allocated_queue(), or QUEUE_FLAG_DEFAULT to q->queue_flags
instead of overwriting.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
b82d4b197c ("blkcg: make request_queue bypassing on allocation") made
request_queues bypassed on allocation to avoid switching on and off
bypass mode on a queue being initialized. Some drivers allocate and
then destroy a lot of queues without fully initializing them and
incurring bypass latency overhead on each of them could add upto
significant overhead.
Unfortunately, blk_init_allocated_queue() is never used by queues of
bio-based drivers, which means that all bio-based driver queues are in
bypass mode even after initialization and registration complete
successfully.
Due to the limited way request_queues are used by bio drivers, this
problem is hidden pretty well but it shows up when blk-throttle is
used in combination with a bio-based driver. Trying to configure
(echoing to cgroupfs file) blk-throttle for a bio-based driver hangs
indefinitely in blkg_conf_prep() waiting for bypass mode to end.
This patch moves the initial blk_queue_bypass_end() call from
blk_init_allocated_queue() to blk_register_queue() which is called for
any userland-visible queues regardless of its type.
I believe this is correct because I don't think there is any block
driver which needs or wants working elevator and blk-cgroup on a queue
which isn't visible to userland. If there are such users, we need a
different solution.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Joseph Glanville <joseph.glanville@orionvm.com.au>
Cc: stable@vger.kernel.org
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Introduce a BLKZEROOUT ioctl which can be used to clear block ranges by
way of blkdev_issue_zeroout().
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
If the device supports WRITE SAME, use that to optimize zeroing of
blocks. If the device does not support WRITE SAME or if the operation
fails, fall back to writing zeroes the old-fashioned way.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The WRITE SAME command supported on some SCSI devices allows the same
block to be efficiently replicated throughout a block range. Only a
single logical block is transferred from the host and the storage device
writes the same data to all blocks described by the I/O.
This patch implements support for WRITE SAME in the block layer. The
blkdev_issue_write_same() function can be used by filesystems and block
drivers to replicate a buffer across a block range. This can be used to
efficiently initialize software RAID devices, etc.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
- blk_check_merge_flags() verifies that cmd_flags / bi_rw are
compatible. This function is called for both req-req and req-bio
merging.
- blk_rq_get_max_sectors() and blk_queue_get_max_sectors() can be used
to query the maximum sector count for a given request or queue. The
calls will return the right value from the queue limits given the
type of command (RW, discard, write same, etc.)
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Remove special-casing of non-rw fs style requests (discard). The nomerge
flags are consolidated in blk_types.h, and rq_mergeable() and
bio_mergeable() have been modified to use them.
bio_is_rw() is used in place of bio_has_data() a few places. This is
done to to distinguish true reads and writes from other fs type requests
that carry a payload (e.g. write same).
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
65536 should be ludicrous anyway but without it we overflow the
memory computation doing the allocation and badness occurs.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Currently, cgroup hierarchy support is a mess. cpu related subsystems
behave correctly - configuration, accounting and control on a parent
properly cover its children. blkio and freezer completely ignore
hierarchy and treat all cgroups as if they're directly under the root
cgroup. Others show yet different behaviors.
These differing interpretations of cgroup hierarchy make using cgroup
confusing and it impossible to co-mount controllers into the same
hierarchy and obtain sane behavior.
Eventually, we want full hierarchy support from all subsystems and
probably a unified hierarchy. Users using separate hierarchies
expecting completely different behaviors depending on the mounted
subsystem is deterimental to making any progress on this front.
This patch adds cgroup_subsys.broken_hierarchy and sets it to %true
for controllers which are lacking in hierarchy support. The goal of
this patch is two-fold.
* Move users away from using hierarchy on currently non-hierarchical
subsystems, so that implementing proper hierarchy support on those
doesn't surprise them.
* Keep track of which controllers are broken how and nudge the
subsystems to implement proper hierarchy support.
For now, start with a single warning message. We can whine louder
later on.
v2: Fixed a typo spotted by Michal. Warning message updated.
v3: Updated memcg part so that it doesn't generate warning in the
cases where .use_hierarchy=false doesn't make the behavior
different from root.use_hierarchy=true. Fixed a typo spotted by
Glauber.
v4: Check ->broken_hierarchy after cgroup creation is complete so that
->create() can affect the result per Michal. Dropped unnecessary
memcg root handling per Michal.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Serge E. Hallyn <serue@us.ibm.com>
Cc: Glauber Costa <glommer@parallels.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Turner <pjt@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Thomas Graf <tgraf@suug.ch>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Remove useless kfree() and clean up code related to the removal.
The semantic patch that finds this problem is as follows:
(http://coccinelle.lip6.fr/)
// <smpl>
@r exists@
position p1,p2;
expression x;
@@
if (x@p1 == NULL) { ... kfree@p2(x); ... return ...; }
@unchanged exists@
position r.p1,r.p2;
expression e <= r.x,x,e1;
iterator I;
statement S;
@@
if (x@p1 == NULL) { ... when != I(x,...) S
when != e = e1
when != e += e1
when != e -= e1
when != ++e
when != --e
when != e++
when != e--
when != &e
kfree@p2(x); ... return ...; }
@ok depends on unchanged exists@
position any r.p1;
position r.p2;
expression x;
@@
... when != true x@p1 == NULL
kfree@p2(x);
@depends on !ok && unchanged@
position r.p2;
expression x;
@@
*kfree@p2(x);
// </smpl>
Signed-off-by: Peter Senna Tschudin <peter.senna@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Before call the blk_queue_congestion_threshold(),
the blk_queue_congestion_threshold() is already called at blk_queue_make_rquest().
Because this code is the duplicated, it has removed.
Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Instead of using simple_strtoul which "converts" invalid numbers to 0,
use strict_strtoul and perform error checking to ensure that userspace
passes us a valid unsigned long. This addresses problems with functions
such as writev, which might want to write a trailing newline -- the
newline should rightfully be rejected, but the value preceeding it
should be preserved.
Fixes BZ#46981.
Signed-off-by: Dave Reisner <dreisner@archlinux.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Previously, there was bio_clone() but it only allocated from the fs bio
set; as a result various users were open coding it and using
__bio_clone().
This changes bio_clone() to become bio_clone_bioset(), and then we add
bio_clone() and bio_clone_kmalloc() as wrappers around it, making use of
the functionality the last patch adedd.
This will also help in a later patch changing how bio cloning works.
Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
CC: NeilBrown <neilb@suse.de>
CC: Alasdair Kergon <agk@redhat.com>
CC: Boaz Harrosh <bharrosh@panasas.com>
CC: Jeff Garzik <jeff@garzik.org>
Acked-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Now that we've got generic code for freeing bios allocated from bio
pools, this isn't needed anymore.
This patch also makes bio_free() static, since without bi_destructor
there should be no need for it to be called anywhere else.
bio_free() is now only called from bio_put, so we can refactor those a
bit - move some code from bio_put() to bio_free() and kill the redundant
bio->bi_next = NULL.
v5: Switch to BIO_KMALLOC_POOL ((void *)~0), per Boaz
v6: BIO_KMALLOC_POOL now NULL, drop bio_free's EXPORT_SYMBOL
v7: No #define BIO_KMALLOC_POOL anymore
Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Now that bios keep track of where they were allocated from,
bio_integrity_alloc_bioset() becomes redundant.
Remove bio_integrity_alloc_bioset() and drop bio_set argument from the
related functions and make them use bio->bi_pool.
Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
CC: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When performing a cable pull test w/ active stress I/O using fio over
a dual port Intel 82599 FCoE CNA, w/ 256LUNs on one port and about 32LUNs
on the other, it is observed that the system becomes not usable due to
scsi-ml being busy printing the error messages for all the failing commands.
I don't believe this problem is specific to FCoE and these commands are
anyway failing due to link being down (DID_NO_CONNECT), just rate-limit
the messages here to solve this issue.
v2->v1: use __ratelimit() as Tomas Henzl mentioned as the proper way for
rate-limit per function. However, in this case, the failed i/o gets to
blk_end_request_err() and then blk_update_request(), which also has to
be rate-limited, as added in the v2 of this patch.
v3-v2: resolved conflict to apply on current 3.6-rc3 upstream tip.
Signed-off-by: Yi Zou <yi.zou@intel.com>
Cc: www.Open-FCoE.org <devel@open-fcoe.org>
Cc: Tomas Henzl <thenzl@redhat.com>
Cc: <linux-scsi@vger.kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Now that cancel_delayed_work() can be safely called from IRQ handlers,
there's no reason to use __cancel_delayed_work(). Use
cancel_delayed_work() instead of __cancel_delayed_work() and mark the
latter deprecated.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Jens Axboe <axboe@kernel.dk>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Roland Dreier <roland@kernel.org>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Now that mod_delayed_work() is safe to call from IRQ handlers,
__cancel_delayed_work() followed by queue_delayed_work() can be
replaced with mod_delayed_work().
Most conversions are straight-forward except for the following.
* net/core/link_watch.c: linkwatch_schedule_work() was doing a quite
elaborate dancing around its delayed_work. Collapse it such that
linkwatch_work is queued for immediate execution if LW_URGENT and
existing timer is kept otherwise.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
system_nrt[_freezable]_wq are now spurious. Mark them deprecated and
convert all users to system[_freezable]_wq.
If you're cc'd and wondering what's going on: Now all workqueues are
non-reentrant, so there's no reason to use system_nrt[_freezable]_wq.
Please use system[_freezable]_wq instead.
This patch doesn't make any functional difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-By: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: David Airlie <airlied@linux.ie>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: David Howells <dhowells@redhat.com>
Convert delayed_work users doing cancel_delayed_work() followed by
queue_delayed_work() to mod_delayed_work().
Most conversions are straight-forward. Ones worth mentioning are,
* drivers/edac/edac_mc.c: edac_mc_workq_setup() converted to always
use mod_delayed_work() and cancel loop in
edac_mc_reset_delay_period() is dropped.
* drivers/platform/x86/thinkpad_acpi.c: No need to remember whether
watchdog is active or not. @fan_watchdog_active and related code
dropped.
* drivers/power/charger-manager.c: Seemingly a lot of
delayed_work_pending() abuse going on here.
[delayed_]work_pending() are unsynchronized and racy when used like
this. I converted one instance in fullbatt_handler(). Please
conver the rest so that it invokes workqueue APIs for the intended
target state rather than trying to game work item pending state
transitions. e.g. if timer should be modified - call
mod_delayed_work(), canceled - call cancel_delayed_work[_sync]().
* drivers/thermal/thermal_sys.c: thermal_zone_device_set_polling()
simplified. Note that round_jiffies() calls in this function are
meaningless. round_jiffies() work on absolute jiffies not delta
delay used by delayed_work.
v2: Tomi pointed out that __cancel_delayed_work() users can't be
safely converted to mod_delayed_work(). They could be calling it
from irq context and if that happens while delayed_work_timer_fn()
is running, it could deadlock. __cancel_delayed_work() users are
dropped.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Acked-by: Anton Vorontsov <cbouatmailru@gmail.com>
Acked-by: David Howells <dhowells@redhat.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Doug Thompson <dougthompson@xmission.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Roland Dreier <roland@kernel.org>
Cc: "John W. Linville" <linville@tuxdriver.com>
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Len Brown <len.brown@intel.com>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
I met a odd prblem:read /proc/partitions may return zero.
I wrote a file test.c:
int main()
{
char buff[4096];
int ret;
int fd;
printf("pid=%d\n",getpid());
while (1) {
fd = open("/proc/partitions", O_RDONLY);
if (fd < 0) {
printf("open error %s\n", strerror(errno));
return 0;
}
ret = read(fd, buff, 4096);
if (ret <= 0)
printf("ret=%d, %s, %ld\n", ret,
strerror(errno), lseek(fd,0,SEEK_CUR));
close(fd);
}
exit(0);
}
You can reproduce by:
1:while true;do cat /proc/partitions > /dev/null ;done
2:./test
I reviewed the code and found:
>> static void *show_partition_start(struct seq_file *seqf, loff_t *pos)
>> {
>> static void *p;
>>
>> p = disk_seqf_start(seqf, pos);
>> if (!IS_ERR_OR_NULL(p) && !*pos)
>> seq_puts(seqf, "major minor #blocks name\n\n");
>> return p;
>> }
test cat /proc/partitions
p = disk_seqf_start()(Not NULL)
p = disk_seqf_start()(NULL because pos)
if (!IS_ERR_OR_NULL(p) && !*pos)
Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add a helper to map a bio to a scatterlist, modelled after
blk_rq_map_sg.
This helper is useful for any driver that wants to create
a scatterlist from its ->make_request_fn method.
Changes in v2:
- Use __blk_segment_map_sg to avoid duplicated code
- Add cocbook style function comment
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Tejun Heo <tj@kernel.org>
Cc: Shaohua Li <shli@kernel.org>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: virtualization@lists.linux-foundation.org
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: Asias He <asias@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Split the mapping code in blk_rq_map_sg() to a helper
__blk_segment_map_sg(), so that other mapping function, e.g.
blk_bio_map_sg(), can share the code.
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Tejun Heo <tj@kernel.org>
Cc: Shaohua Li <shli@kernel.org>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: virtualization@lists.linux-foundation.org
Suggested-by: Jens Axboe <axboe@kernel.dk>
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Asias He <asias@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When a disk has large discard_granularity and small max_discard_sectors,
discards are not split with optimal alignment. In the limit case of
discard_granularity == max_discard_sectors, no request could be aligned
correctly, so in fact you might end up with no discarded logical blocks
at all.
Another example that helps showing the condition in the patch is with
discard_granularity == 64, max_discard_sectors == 128. A request that is
submitted for 256 sectors 2..257 will be split in two: 2..129, 130..257.
However, only 2 aligned blocks out of 3 are included in the request;
128..191 may be left intact and not discarded. With this patch, the
first request will be truncated to ensure good alignment of what's left,
and the split will be 2..127, 128..255, 256..257. The patch will also
take into account the discard_alignment.
At most one extra request will be introduced, because the first request
will be reduced by at most granularity-1 sectors, and granularity
must be less than max_discard_sectors. Subsequent requests will run
on round_down(max_discard_sectors, granularity) sectors, as in the
current code.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Tested-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Mostly a preparation for the next patch.
In principle this fixes an infinite loop if max_discard_sectors < granularity,
but that really shouldn't happen.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Tested-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull block driver changes from Jens Axboe:
- Making the plugging support for drivers a bit more sane from Neil.
This supersedes the plugging change from Shaohua as well.
- The usual round of drbd updates.
- Using a tail add instead of a head add in the request completion for
ndb, making us find the most completed request more quickly.
- A few floppy changes, getting rid of a duplicated flag and also
running the floppy init async (since it takes forever in boot terms)
from Andi.
* 'for-3.6/drivers' of git://git.kernel.dk/linux-block:
floppy: remove duplicated flag FD_RAW_NEED_DISK
blk: pass from_schedule to non-request unplug functions.
block: stack unplug
blk: centralize non-request unplug handling.
md: remove plug_cnt feature of plugging.
block/nbd: micro-optimization in nbd request completion
drbd: announce FLUSH/FUA capability to upper layers
drbd: fix max_bio_size to be unsigned
drbd: flush drbd work queue before invalidate/invalidate remote
drbd: fix potential access after free
drbd: call local-io-error handler early
drbd: do not reset rs_pending_cnt too early
drbd: reset congestion information before reporting it in /proc/drbd
drbd: report congestion if we are waiting for some userland callback
drbd: differentiate between normal and forced detach
drbd: cleanup, remove two unused global flags
floppy: Run floppy initialization asynchronous
Pull core block IO bits from Jens Axboe:
"The most complicated part if this is the request allocation rework by
Tejun, which has been queued up for a long time and has been in
for-next ditto as well.
There are a few commits from yesterday and today, mostly trivial and
obvious fixes. So I'm pretty confident that it is sound. It's also
smaller than usual."
* 'for-3.6/core' of git://git.kernel.dk/linux-block:
block: remove dead func declaration
block: add partition resize function to blkpg ioctl
block: uninitialized ioc->nr_tasks triggers WARN_ON
block: do not artificially constrain max_sectors for stacking drivers
blkcg: implement per-blkg request allocation
block: prepare for multiple request_lists
block: add q->nr_rqs[] and move q->rq.elvpriv to q->nr_rqs_elvpriv
blkcg: inline bio_blkcg() and friends
block: allocate io_context upfront
block: refactor get_request[_wait]()
block: drop custom queue draining used by scsi_transport_{iscsi|fc}
mempool: add @gfp_mask to mempool_create_node()
blkcg: make root blkcg allocation use %GFP_KERNEL
blkcg: __blkg_lookup_create() doesn't need radix preload
__generic_unplug_device() function is removed with commit
7eaceaccab, which forgot to
remove the declaration at meantime. Here remove it.
Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add a new operation code (BLKPG_RESIZE_PARTITION) to the BLKPG ioctl that
allows altering the size of an existing partition, even if it is currently
in use.
This patch converts hd_struct->nr_sects into sequence counter because
One might extend a partition while IO is happening to it and update of
nr_sects can be non-atomic on 32bit machines with 64bit sector_t. This
can lead to issues like reading inconsistent size of a partition. Sequence
counter have been used so that readers don't have to take bdev mutex lock
as we call sector_in_part() very frequently.
Now all the access to hd_struct->nr_sects should happen using sequence
counter read/update helper functions part_nr_sects_read/part_nr_sects_write.
There is one exception though, set_capacity()/get_capacity(). I think
theoritically race should exist there too but this patch does not
modify set_capacity()/get_capacity() due to sheer number of call sites
and I am afraid that change might break something. I have left that as a
TODO item. We can handle it later if need be. This patch does not introduce
any new races as such w.r.t set_capacity()/get_capacity().
v2: Add CONFIG_LBDAF test to UP preempt case as suggested by Phillip.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Phillip Susi <psusi@ubuntu.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Hi,
I'm using the old-fashioned 'dump' backup tool, and I noticed that it spews the
below warning as of 3.5-rc1 and later (3.4 is fine):
[ 10.886893] ------------[ cut here ]------------
[ 10.886904] WARNING: at include/linux/iocontext.h:140 copy_process+0x1488/0x1560()
[ 10.886905] Hardware name: Bochs
[ 10.886906] Modules linked in:
[ 10.886908] Pid: 2430, comm: dump Not tainted 3.5.0-rc7+ #27
[ 10.886908] Call Trace:
[ 10.886911] [<ffffffff8107ce8a>] warn_slowpath_common+0x7a/0xb0
[ 10.886912] [<ffffffff8107ced5>] warn_slowpath_null+0x15/0x20
[ 10.886913] [<ffffffff8107c088>] copy_process+0x1488/0x1560
[ 10.886914] [<ffffffff8107c244>] do_fork+0xb4/0x340
[ 10.886918] [<ffffffff8108effa>] ? recalc_sigpending+0x1a/0x50
[ 10.886919] [<ffffffff8108f6b2>] ? __set_task_blocked+0x32/0x80
[ 10.886920] [<ffffffff81091afa>] ? __set_current_blocked+0x3a/0x60
[ 10.886923] [<ffffffff81051db3>] sys_clone+0x23/0x30
[ 10.886925] [<ffffffff8179bd73>] stub_clone+0x13/0x20
[ 10.886927] [<ffffffff8179baa2>] ? system_call_fastpath+0x16/0x1b
[ 10.886928] ---[ end trace 32a14af7ee6a590b ]---
Reproducing is easy, I can hit it on a KVM system with a very basic
config (x86_64 make defconfig + enable the drivers needed). To hit it,
just install dump (on debian/ubuntu, not sure what the package might be
called on Fedora), and:
dump -o -f /tmp/foo /
You'll see the warning in dmesg once it forks off the I/O process and
starts dumping filesystem contents.
I bisected it down to the following commit:
commit f6e8d01bee
Author: Tejun Heo <tj@kernel.org>
Date: Mon Mar 5 13:15:26 2012 -0800
block: add io_context->active_ref
Currently ioc->nr_tasks is used to decide two things - whether an ioc
is done issuing IOs and whether it's shared by multiple tasks. This
patch separate out the first into ioc->active_ref, which is acquired
and released using {get|put}_io_context_active() respectively.
This will be used to associate bio's with a given task. This patch
doesn't introduce any visible behavior change.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
It seems like the init of ioc->nr_tasks was removed in that patch,
so it starts out at 0 instead of 1.
Tejun, is the right thing here to add back the init, or should something else
be done?
The below patch removes the warning, but I haven't done any more extensive
testing on it.
Signed-off-by: Olof Johansson <olof@lixom.net>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
blk_set_stacking_limits is intended to allow stacking drivers to build
up the limits of the stacked device based on the underlying devices'
limits. But defaulting 'max_sectors' to BLK_DEF_MAX_SECTORS (1024)
doesn't allow the stacking driver to inherit a max_sectors larger than
1024 -- due to blk_stack_limits' use of min_not_zero.
It is now clear that this artificial limit is getting in the way so
change blk_set_stacking_limits's max_sectors to UINT_MAX (which allows
stacking drivers like dm-multipath to inherit 'max_sectors' from the
underlying paths).
Reported-by: Vijay Chauhan <vijay.chauhan@netapp.com>
Tested-by: Vijay Chauhan <vijay.chauhan@netapp.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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>
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>
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>
If the queue is dead blk_execute_rq_nowait() doesn't invoke the done()
callback function. That will result in blk_execute_rq() being stuck
in wait_for_completion(). Avoid this by initializing rq->end_io to the
done() callback before we check the queue state. Also, make sure the
queue lock is held around the invocation of the done() callback. Found
this through source code review.
Signed-off-by: Muthukumar Ratty <muthur@gmail.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Tejun Heo <tj@kernel.org>
Acked-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
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>
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>
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>
Make bio_blkcg() and friends inline. They all are very simple and
used only in few places.
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>
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>
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>
iscsi_remove_host() uses bsg_remove_queue() which implements custom
queue draining. fc_bsg_remove() open-codes mostly identical logic.
The draining logic isn't correct in that blk_stop_queue() doesn't
prevent new requests from being queued - it just stops processing, so
nothing prevents new requests to be queued after the logic determines
that the queue is drained.
blk_cleanup_queue() now implements proper queue draining and these
custom draining logics aren't necessary. Drop them and use
bsg_unregister_queue() + blk_cleanup_queue() instead.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: James Smart <james.smart@emulex.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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>
Currently, blkcg_activate_policy() depends on %GFP_ATOMIC allocation
from __blkg_lookup_create() for root blkcg creation. This could make
policy fail unnecessarily.
Make blkg_alloc() take @gfp_mask, __blkg_lookup_create() take an
optional @new_blkg for preallocated blkg, and blkcg_activate_policy()
preload radix tree and preallocate blkg with %GFP_KERNEL before trying
to create the root blkg.
v2: __blkg_lookup_create() was returning %NULL on blkg alloc failure
instead of ERR_PTR() value. Fixed.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
There's no point in calling radix_tree_preload() if preloading doesn't
use more permissible GFP mask. Drop preloading from
__blkg_lookup_create().
While at it, drop sparse locking annotation which no longer applies.
v2: Vivek pointed out the odd preload usage. Instead of updating,
just drop it.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Sometimes, warnings about ioctls to partition happen often enough that they
form majority of the warnings in the kernel log and users complain. In some
cases warnings are about ioctls such as SG_IO so it's not good to get rid of
the warnings completely as they can ease debugging of userspace problems
when ioctl is refused.
Since I have seen warnings from lots of commands, including some proprietary
userspace applications, I don't think disallowing the ioctls for processes
with CAP_SYS_RAWIO will happen in the near future if ever. So lets just
stop warning for processes with CAP_SYS_RAWIO for which ioctl is allowed.
CC: Paolo Bonzini <pbonzini@redhat.com>
CC: James Bottomley <JBottomley@parallels.com>
CC: linux-scsi@vger.kernel.org
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This function was only used by btrfs code in btrfs_abort_devices()
(seems in a wrong way).
It was removed in commit d07eb91170,
So, Let's remove the dead code to avoid any confusion.
Changes in v2: update commit log, btrfs_abort_devices() was removed
already.
Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-kernel@vger.kernel.org
Cc: Chris Mason <chris.mason@oracle.com>
Cc: linux-btrfs@vger.kernel.org
Cc: David Sterba <dave@jikos.cz>
Signed-off-by: Asias He <asias@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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>
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>
blkg_destroy() caches @blkg->q in local variable @q. While there are
two places which needs @blkg->q, only lockdep_assert_held() used the
local variable leading to unused local variable warning if lockdep is
configured out. Drop the local variable and just use @blkg->q
directly.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Rakesh Iyer <rni@google.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When policy data allocation fails in the middle, blkg_alloc() invokes
blkg_free() to destroy the half constructed blkg. This ends up
calling pd_exit_fn() on policy datas which didn't go through
pd_init_fn(). Fix it by making blkg_alloc() call pd_init_fn()
immediately after each policy data allocation.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
cfq may be built w/ or w/o blkcg support depending on
CONFIG_CFQ_CGROUP_IOSCHED. If blkcg support is disabled, most of
related code is ifdef'd out but some part is left dangling -
blkcg_policy_cfq is left zero-filled and blkcg_policy_[un]register()
calls are made on it.
Feeding zero filled policy to blkcg_policy_register() is incorrect and
triggers the following WARN_ON() if CONFIG_BLK_CGROUP &&
!CONFIG_CFQ_GROUP_IOSCHED.
------------[ cut here ]------------
WARNING: at block/blk-cgroup.c:867
Modules linked in:
Modules linked in:
CPU: 3 Not tainted 3.4.0-09547-gfb21aff #1
Process swapper/0 (pid: 1, task: 000000003ff80000, ksp: 000000003ff7f8b8)
Krnl PSW : 0704100180000000 00000000003d76ca (blkcg_policy_register+0xca/0xe0)
R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:0 CC:1 PM:0 EA:3
Krnl GPRS: 0000000000000000 00000000014b85ec 00000000014b85b0 0000000000000000
000000000096fb60 0000000000000000 00000000009a8e78 0000000000000048
000000000099c070 0000000000b6f000 0000000000000000 000000000099c0b8
00000000014b85b0 0000000000667580 000000003ff7fd98 000000003ff7fd70
Krnl Code: 00000000003d76be: a7280001 lhi %r2,1
00000000003d76c2: a7f4ffdf brc 15,3d7680
#00000000003d76c6: a7f40001 brc 15,3d76c8
>00000000003d76ca: a7c8ffea lhi %r12,-22
00000000003d76ce: a7f4ffce brc 15,3d766a
00000000003d76d2: a7f40001 brc 15,3d76d4
00000000003d76d6: a7c80000 lhi %r12,0
00000000003d76da: a7f4ffc2 brc 15,3d765e
Call Trace:
([<0000000000b6f000>] initcall_debug+0x0/0x4)
[<0000000000989e8a>] cfq_init+0x62/0xd4
[<00000000001000ba>] do_one_initcall+0x3a/0x170
[<000000000096fb60>] kernel_init+0x214/0x2bc
[<0000000000623202>] kernel_thread_starter+0x6/0xc
[<00000000006231fc>] kernel_thread_starter+0x0/0xc
no locks held by swapper/0/1.
Last Breaking-Event-Address:
[<00000000003d76c6>] blkcg_policy_register+0xc6/0xe0
---[ end trace b8ef4903fcbf9dd3 ]---
This patch fixes the problem by ensuring all blkcg support code is
inside CONFIG_CFQ_GROUP_IOSCHED.
* blkcg_policy_cfq declaration and blkg_to_cfqg() definition are moved
inside the first CONFIG_CFQ_GROUP_IOSCHED block. __maybe_unused is
dropped from blkcg_policy_cfq decl.
* blkcg_deactivate_poilcy() invocation is moved inside ifdef. This
also makes the activation logic match cfq_init_queue().
* All blkcg_policy_[un]register() invocations are moved inside ifdef.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com>
LKML-Reference: <20120601112954.GC3535@osiris.boeblingen.de.ibm.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
cfq_init() would return zero after kmem cache creation failure. Fix
so that it returns -ENOMEM.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Calling get_task_io_context() on a exiting task which isn't %current can
loop forever. This triggers at boot time on my dev machine.
BUG: soft lockup - CPU#3 stuck for 22s ! [mountall.1603]
Fix this by making create_task_io_context() returns -EBUSY in this case
to break the loop.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Alan Cox <alan@linux.intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Merge block/IO core bits from Jens Axboe:
"This is a bit bigger on the core side than usual, but that is purely
because we decided to hold off on parts of Tejun's submission on 3.4
to give it a bit more time to simmer. As a consequence, it's seen a
long cycle in for-next.
It contains:
- Bug fix from Dan, wrong locking type.
- Relax splice gifting restriction from Eric.
- A ton of updates from Tejun, primarily for blkcg. This improves
the code a lot, making the API nicer and cleaner, and also includes
fixes for how we handle and tie policies and re-activate on
switches. The changes also include generic bug fixes.
- A simple fix from Vivek, along with a fix for doing proper delayed
allocation of the blkcg stats."
Fix up annoying conflict just due to different merge resolution in
Documentation/feature-removal-schedule.txt
* 'for-3.5/core' of git://git.kernel.dk/linux-block: (92 commits)
blkcg: tg_stats_alloc_lock is an irq lock
vmsplice: relax alignement requirements for SPLICE_F_GIFT
blkcg: use radix tree to index blkgs from blkcg
blkcg: fix blkcg->css ref leak in __blkg_lookup_create()
block: fix elvpriv allocation failure handling
block: collapse blk_alloc_request() into get_request()
blkcg: collapse blkcg_policy_ops into blkcg_policy
blkcg: embed struct blkg_policy_data in policy specific data
blkcg: mass rename of blkcg API
blkcg: style cleanups for blk-cgroup.h
blkcg: remove blkio_group->path[]
blkcg: blkg_rwstat_read() was missing inline
blkcg: shoot down blkgs if all policies are deactivated
blkcg: drop stuff unused after per-queue policy activation update
blkcg: implement per-queue policy activation
blkcg: add request_queue->root_blkg
blkcg: make request_queue bypassing on allocation
blkcg: make sure blkg_lookup() returns %NULL if @q is bypassing
blkcg: make blkg_conf_prep() take @pol and return with queue lock held
blkcg: remove static policy ID enums
...
tg_stats_alloc_lock nests inside queue lock and should always be held
with irq disabled. throtl_pd_{init|exit}() were using non-irqsafe
spinlock ops which triggered inverse lock ordering via irq warning via
RCU freeing of blkg invoking throtl_pd_exit() w/o disabling IRQ.
Update both functions to use irq safe operations.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Sasha Levin <sasha.levin@oracle.com>
LKML-Reference: <1335339396.16988.80.camel@lappy>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull cgroup updates from Tejun Heo:
"cgroup file type addition / removal is updated so that file types are
added and removed instead of individual files so that dynamic file
type addition / removal can be implemented by cgroup and used by
controllers. blkio controller changes which will come through block
tree are dependent on this. Other changes include res_counter cleanup
and disallowing kthread / PF_THREAD_BOUND threads to be attached to
non-root cgroups.
There's a reported bug with the file type addition / removal handling
which can lead to oops on cgroup umount. The issue is being looked
into. It shouldn't cause problems for most setups and isn't a
security concern."
Fix up trivial conflict in Documentation/feature-removal-schedule.txt
* 'for-3.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (21 commits)
res_counter: Account max_usage when calling res_counter_charge_nofail()
res_counter: Merge res_counter_charge and res_counter_charge_nofail
cgroups: disallow attaching kthreadd or PF_THREAD_BOUND threads
cgroup: remove cgroup_subsys->populate()
cgroup: get rid of populate for memcg
cgroup: pass struct mem_cgroup instead of struct cgroup to socket memcg
cgroup: make css->refcnt clearing on cgroup removal optional
cgroup: use negative bias on css->refcnt to block css_tryget()
cgroup: implement cgroup_rm_cftypes()
cgroup: introduce struct cfent
cgroup: relocate __d_cgrp() and __d_cft()
cgroup: remove cgroup_add_file[s]()
cgroup: convert memcg controller to the new cftype interface
memcg: always create memsw files if CONFIG_CGROUP_MEM_RES_CTLR_SWAP
cgroup: convert all non-memcg controllers to the new cftype interface
cgroup: relocate cftype and cgroup_subsys definitions in controllers
cgroup: merge cft_release_agent cftype array into the base files array
cgroup: implement cgroup_add_cftypes() and friends
cgroup: build list of all cgroups under a given cgroupfs_root
cgroup: move cgroup_clear_directory() call out of cgroup_populate_dir()
...
To avoid confusion while formatting a DASD device change the level of
the "Expected VOL1 label not found" message from warning to info.
Signed-off-by: Stefan Haberland <stefan.haberland@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
6d1d8050b4 "block, partition: add partition_meta_info to hd_struct"
added part_unpack_uuid() which assumes that the passed in buffer has
enough space for sprintfing "%pU" - 37 characters including '\0'.
Unfortunately, b5af921ec0 "init: add support for root devices
specified by partition UUID" supplied 33 bytes buffer to the function
leading to the following panic with stackprotector enabled.
Kernel panic - not syncing: stack-protector: Kernel stack corrupted in: ffffffff81b14c7e
[<ffffffff815e226b>] panic+0xba/0x1c6
[<ffffffff81b14c7e>] ? printk_all_partitions+0x259/0x26xb
[<ffffffff810566bb>] __stack_chk_fail+0x1b/0x20
[<ffffffff81b15c7e>] printk_all_paritions+0x259/0x26xb
[<ffffffff81aedfe0>] mount_block_root+0x1bc/0x27f
[<ffffffff81aee0fa>] mount_root+0x57/0x5b
[<ffffffff81aee23b>] prepare_namespace+0x13d/0x176
[<ffffffff8107eec0>] ? release_tgcred.isra.4+0x330/0x30
[<ffffffff81aedd60>] kernel_init+0x155/0x15a
[<ffffffff81087b97>] ? schedule_tail+0x27/0xb0
[<ffffffff815f4d24>] kernel_thread_helper+0x5/0x10
[<ffffffff81aedc0b>] ? start_kernel+0x3c5/0x3c5
[<ffffffff815f4d20>] ? gs_change+0x13/0x13
Increase the buffer size, remove the dangerous part_unpack_uuid() and
use snprintf() directly from printk_all_partitions().
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Szymon Gruszczynski <sz.gruszczynski@googlemail.com>
Cc: Will Drewry <wad@chromium.org>
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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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>
blkg lookup is currently performed by traversing linked list anchored
at blkcg->blkg_list. This is very unscalable and with blk-throttle
enabled and enough request queues on the system, this can get very
ugly quickly (blk-throttle performs look up on every bio submission).
This patch makes blkcg use radix tree to index blkgs combined with
simple last-looked-up hint. This is mostly identical to how icqs are
indexed from ioc.
Note that because __blkg_lookup() may be invoked without holding queue
lock, hint is only updated from __blkg_lookup_create(). Due to cfq's
cfqq caching, this makes hint updates overly lazy. This will be
improved with scheduled blkcg aware request allocation.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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>
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>
There's no reason to keep blkcg_policy_ops separate. Collapse it into
blkcg_policy.
This patch doesn't introduce any functional change.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Currently blkg_policy_data carries policy specific data as char flex
array instead of being embedded in policy specific data. This was
forced by oddities around blkg allocation which are all gone now.
This patch makes blkg_policy_data embedded in policy specific data -
throtl_grp and cfq_group so that it's more conventional and consistent
with how io_cq is handled.
* blkcg_policy->pdata_size is renamed to ->pd_size.
* Functions which used to take void *pdata now takes struct
blkg_policy_data *pd.
* blkg_to_pdata/pdata_to_blkg() updated to blkg_to_pd/pd_to_blkg().
* Dummy struct blkg_policy_data definition added. Dummy
pdata_to_blkg() definition was unused and inconsistent with the
non-dummy version - correct dummy pd_to_blkg() added.
* throtl and cfq updated accordingly.
* As dummy blkg_to_pd/pd_to_blkg() are provided,
blkg_to_cfqg/cfqg_to_blkg() don't need to be ifdef'd. Moved outside
ifdef block.
This patch doesn't introduce any functional change.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
During the recent blkcg cleanup, most of blkcg API has changed to such
extent that mass renaming wouldn't cause any noticeable pain. Take
the chance and cleanup the naming.
* Rename blkio_cgroup to blkcg.
* Drop blkio / blkiocg prefixes and consistently use blkcg.
* Rename blkio_group to blkcg_gq, which is consistent with io_cq but
keep the blkg prefix / variable name.
* Rename policy method type and field names to signify they're dealing
with policy data.
* Rename blkio_policy_type to blkcg_policy.
This patch doesn't cause any functional change.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
* Update indentation on struct field declarations.
* Uniformly don't use "extern" on function declarations.
* Merge the two #ifdef CONFIG_BLK_CGROUP blocks.
All changes in this patch are cosmetic.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
blkio_group->path[] stores the path of the associated cgroup and is
used only for debug messages. Just format the path from blkg->cgroup
when printing debug messages.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
There's no reason to keep blkgs around if no policy is activated for
the queue. This patch moves queue locking out of blkg_destroy_all()
and call it from blkg_deactivate_policy() on deactivation of the last
policy on the queue.
This change was 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>
* All_q_list is unused. Drop all_q_{mutex|list}.
* @for_root of blkg_lookup_create() is always %false when called from
outside blk-cgroup.c proper. Factor out __blkg_lookup_create() so
that it doesn't check whether @q is bypassing and use the
underscored version for the @for_root callsite.
* blkg_destroy_all() is used only from blkcg proper and @destroy_root
is always %true. Make it static and drop @destroy_root.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
All blkcg policies were assumed to be enabled on all request_queues.
Due to various implementation obstacles, during the recent blkcg core
updates, this was temporarily implemented as shooting down all !root
blkgs on elevator switch and policy [de]registration combined with
half-broken in-place root blkg updates. In addition to being buggy
and racy, this meant losing all blkcg configurations across those
events.
Now that blkcg is cleaned up enough, this patch replaces the temporary
implementation with proper per-queue policy activation. Each blkcg
policy should call the new blkcg_[de]activate_policy() to enable and
disable the policy on a specific queue. blkcg_activate_policy()
allocates and installs policy data for the policy for all existing
blkgs. blkcg_deactivate_policy() does the reverse. If a policy is
not enabled for a given queue, blkg printing / config functions skip
the respective blkg for the queue.
blkcg_activate_policy() also takes care of root blkg creation, and
cfq_init_queue() and blk_throtl_init() are updated accordingly.
This replaces blkcg_bypass_{start|end}() and update_root_blkg_pd()
unnecessary. Dropped.
v2: cfq_init_queue() was returning uninitialized @ret on root_group
alloc failure if !CONFIG_CFQ_GROUP_IOSCHED. Fixed.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
With per-queue policy activation, root blkg creation will be moved to
blkcg core. Add q->root_blkg in preparation. For blk-throtl, this
replaces throtl_data->root_tg; however, cfq needs to keep
cfqd->root_group for !CONFIG_CFQ_GROUP_IOSCHED.
This is to prepare for per-queue policy activation and doesn't cause
any functional difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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>
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>
