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blkcg is gonna switch to cgroup common weight range as defined by
CGROUP_WEIGHT_* on the unified hierarchy. In preparation, rename
CFQ_WEIGHT_* constants to CFQ_WEIGHT_LEGACY_*.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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blkcg interface grew to be the biggest of all controllers and
unfortunately most inconsistent too. The interface files are
inconsistent with a number of cloes duplicates. Some files have
recursive variants while others don't. There's distinction between
normal and leaf weights which isn't intuitive and there are a lot of
stat knobs which don't make much sense outside of debugging and expose
too much implementation details to userland.
In the unified hierarchy, everything is always hierarchical and
internal nodes can't have tasks rendering the two structural issues
twisting the current interface. The interface has to be updated in a
significant anyway and this is a good chance to revamp it as a whole.
This patch implements blkcg interface for the unified hierarchy.
* (from a previous patch) blkcg is identified by "io" instead of
"blkio" on the unified hierarchy. Given that the whole interface is
updated anyway, the rename shouldn't carry noticeable conversion
overhead.
* The original interface consisted of 27 files is replaced with the
following three files.
blkio.stat : per-blkcg stats
blkio.weight : per-cgroup and per-cgroup-queue weight settings
blkio.max : per-cgroup-queue bps and iops max limits
Documentation/cgroups/unified-hierarchy.txt updated accordingly.
v2: blkcg_policy->dfl_cftypes wasn't removed on
blkcg_policy_unregister() corrupting the cftypes list. Fixed.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
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* Export blkg_dev_name()
* Drop unnecessary @cft from __cfq_set_weight().
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
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tg_set_conf() is largely consisted of parsing and setting the new
config and the follow-up application and propagation. This patch
separates out the latter part into tg_conf_updated(). This will be
used to implement interface for the unified hierarchy.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
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Currently, blkg_conf_prep() expects input to be of the following form
MAJ:MIN NUM
and reads the NUM part into blkg_conf_ctx->v. This is quite
restrictive and gets in the way in implementing blkcg interface for
the unified hierarchy. This patch updates blkg_conf_prep() so that it
expects
MAJ:MIN BODY_STR
where BODY_STR is an arbitrary string. blkg_conf_ctx->v is replaced
with ->body which is a char pointer pointing to the start of BODY_STR.
Parsing of the body is moved to blkg_conf_prep()'s callers.
To allow using, for example, strsep() on blkg_conf_ctx->val, it is a
non-const pointer and to accommodate that const is dropped from @input
too.
This doesn't cause any behavior changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
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blkcg is about to grow interface for the unified hierarchy. Add
legacy to existing cftypes.
* blkcg_policy->cftypes -> blkcg_policy->legacy_cftypes
* blk-cgroup.c:blkcg_files -> blkcg_legacy_files
* cfq-iosched.c:cfq_blkcg_files -> cfq_blkcg_legacy_files
* blk-throttle.c:throtl_files -> throtl_legacy_files
Pure renames. No functional change.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
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blkio interface has become messy over time and is currently the
largest. In addition to the inconsistent naming scheme, it has
multiple stat files which report more or less the same thing, a number
of debug stat files which expose internal details which shouldn't have
been part of the public interface in the first place, recursive and
non-recursive stats and leaf and non-leaf knobs.
Both recursive vs. non-recursive and leaf vs. non-leaf distinctions
don't make any sense on the unified hierarchy as only leaf cgroups can
contain processes. cgroups is going through a major interface
revision with the unified hierarchy involving significant fundamental
usage changes and given that a significant portion of the interface
doesn't make sense anymore, it's a good time to reorganize the
interface.
As the first step, this patch renames the external visible subsystem
name from "blkio" to "io". This is more concise, matches the other
two major subsystem names, "cpu" and "memory", and better suited as
blkcg will be involved in anything writeback related too whether an
actual block device is involved or not.
As the subsystem legacy_name is set to "blkio", the only userland
visible change outside the unified hierarchy is that blkcg is reported
as "io" instead of "blkio" in the subsystem initialized message during
boot. On the unified hierarchy, blkcg now appears as "io".
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: cgroups@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@fb.com>
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blkcg currently returns -EINVAL for most errors which can be pretty
confusing given that the failure modes are quite varied. Update the
error returns so that
* -EINVAL only for syntactic errors.
* -ERANGE if the value is out of range.
* -ENODEV if the target device can't be found.
* -EOPNOTSUPP if the policy is not enabled on the target device.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
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blkg_to_cfqg() and blkcg_to_cfqgd() on a valid blkg with the policy
enabled are guaranteed to return non-NULL and the counterpart in
blk-throttle doesn't have these checks either. Remove the spurious
NULL checks.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
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The recent percpu conversion of blkg_rwstat triggered the following
warning in certain configurations.
block/blk-cgroup.c:654:1: warning: the frame size of 1360 bytes is larger than 1024 bytes
This is because blkg_rwstat now contains four percpu_counter which can
be pretty big depending on debug options although it shouldn't be a
problem in production configs. This patch removes one of the two
local blkg_rwstat variables used by blkg_rwstat_recursive_sum() to
reduce stack usage.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Link: http://article.gmane.org/gmane.linux.kernel.cgroups/13835
Signed-off-by: Jens Axboe <axboe@fb.com>
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cfq_stats->sectors is a blkg_stat which keeps track of the total
number of sectors serviced; however, this can be trivially calculated
from blkcg_gq->stat_bytes. The only thing necessary is adding up
READs and WRITEs and then dividing by sector size.
Remove cfqg_stats->sectors and make cfq print "sectors" and
"sectors_recursive" from stat_bytes.
While this is a bit more code, it removes duplicate stat allocations
and updates and ensures that the reported stats stay in tune with each
other.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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Currently, both cfq-iosched and blk-throttle keep track of
io_service_bytes and io_serviced stats. While keeping track of them
separately may be useful during development, it doesn't make much
sense otherwise. Also, blk-throttle was counting bio's as IOs while
cfq-iosched request's, which is more confusing than informative.
This patch adds ->stat_bytes and ->stat_ios to blkg (blkcg_gq),
removes the counterparts from cfq-iosched and blk-throttle and let
them print from the common blkg counters. The common counters are
incremented during bio issue in blkcg_bio_issue_check().
The outputs are still filtered by whether the policy has
blkg_policy_data on a given blkg, so cfq's output won't show up if it
has never been used for a given blkg. The only times when the outputs
would differ significantly are when policies are attached on the fly
or elevators are switched back and forth. Those are quite exceptional
operations and I don't think they warrant keeping separate counters.
v3: Update blkio-controller.txt accordingly.
v2: Account IOs during bio issues instead of request completions so
that bio-based drivers can be handled the same way.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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Currently, blkg_[rw]stat_recursive_sum() assume that the target
counter is located in pd (blkg_policy_data); however, some counters
are planned to be moved to blkg (blkcg_gq).
This patch updates blkg_[rw]stat_recursive_sum() to take blkg and
blkg_policy pointers instead of pd. If policy is NULL, it indexes
into blkg. If non-NULL, into the blkg's pd of the policy.
The existing usages are updated to maintain the current behaviors.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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blkcg_[rw]stat are used as stat counters for blkcg policies. It isn't
per-cpu by itself and blk-throttle makes it per-cpu by wrapping around
it. This patch makes blkcg_[rw]stat per-cpu and drop the ad-hoc
per-cpu wrapping in blk-throttle.
* blkg_[rw]stat->cnt is replaced with cpu_cnt which is struct
percpu_counter. This makes syncp unnecessary as remote accesses are
handled by percpu_counter itself.
* blkg_[rw]stat_init() can now fail due to percpu allocation failure
and thus are updated to return int.
* percpu_counters need explicit freeing. blkg_[rw]stat_exit() added.
* As blkg_rwstat->cpu_cnt[] can't be read directly anymore, reading
and summing results are stored in ->aux_cnt[] instead.
* Custom per-cpu stat implementation in blk-throttle is removed.
This makes all blkcg stat counters per-cpu without complicating policy
implmentations.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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cgroup stats are local to each cgroup and doesn't propagate to
ancestors by default. When recursive stats are necessary, the sum is
calculated over all the descendants. This initially was for backward
compatibility to support both group-local and recursive stats but this
mode of operation makes general sense as stat update is much hotter
thafn reporting those stats.
This however ends up losing recursive stats when a child is removed.
To work around this, cfq-iosched adds its stats to its parent
cfq_group->dead_stats which is summed up together when calculating
recursive stats.
It's planned that the core stats will be moved to blkcg_gq, so we want
to move the mechanism for keeping track of the stats of dead children
from cfq to blkcg core. This patch adds blkg_[rw]stat->aux_cnt which
are atomic64_t's keeping track of auxiliary counts which are excluded
when reading local counts but included for recursive.
blkg_[rw]stat_merge() which were used by cfq to implement dead_stats
are replaced by blkg_[rw]stat_add_aux(), and cfq now forwards stats of
a dead cgroup to the aux counts of parent->stats instead of separate
->dead_stats.
This will also help making blkg_[rw]stats per-cpu.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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blkg (blkcg_gq) currently is created by blkcg policies invoking
blkg_lookup_create() which ends up repeating about the same code in
different policies. Theoretically, this can avoid the overhead of
looking and/or creating blkg's if blkcg is enabled but no policy is in
use; however, the cost of blkg lookup / creation is very low
especially if only the root blkcg is in use which is highly likely if
no blkcg policy is in active use - it boils down to a single very
predictable conditional and surrounding RCU protection.
This patch consolidates blkg creation to a new function
blkcg_bio_issue_check() which is called during bio issue from
generic_make_request_checks(). blkcg_bio_issue_check() is now the
only function which tries to create missing blkg's. The subsequent
policy and request_list operations just perform blkg_lookup() and if
missing falls back to the root.
* blk_get_rl() no longer tries to create blkg. It uses blkg_lookup()
instead of blkg_lookup_create().
* blk_throtl_bio() is now called from blkcg_bio_issue_check() with rcu
read locked and blkg already looked up. Both throtl_lookup_tg() and
throtl_lookup_create_tg() are dropped.
* cfq is similarly updated. cfq_lookup_create_cfqg() is replaced with
cfq_lookup_cfqg()which uses blkg_lookup().
This consolidates blkg handling and avoids unnecessary blkg creation
retries under memory pressure. In addition, this provides a common
bio entry point into blkcg where things like common accounting can be
performed.
v2: Build fixes for !CONFIG_CFQ_GROUP_IOSCHED and
!CONFIG_BLK_DEV_THROTTLING.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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If a queue is bypassing, all blkcg policies should become noops but
blk-throttle wasn't. It only became noop if the queue was dying.
While this wouldn't lead to an oops as falling back to the root blkg
is safe in this case, this can be a bit surprising - a bypassing queue
could still be applying throttle limits.
Fix it by removing blk_queue_dying() test in throtl_lookup_create_tg()
and testing blk_queue_bypass() in blk_throtl_bio() and bypassing
before doing anything else.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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Currently, both throttle and cfq policies implement their own root
blkg (blkcg_gq) lookup fast path. This patch moves root blkg
optimization from throtl_lookup_tg() to __blkg_lookup(). cfq-iosched
currently doesn't use blkg_lookup() but will be converted and drop the
optimization too.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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blkg_lookup() checks whether the target queue is bypassing and, if
not, calls __blkg_lookup() which first checks the lookup hint and then
performs radix tree walk. The operations upto hint checking are
trivial and there are many users of this function. This patch inlines
blkg_lookup() and the fast path part of __blkg_lookup(). The radix
tree lookup and hint update are now in blkg_lookup_slowpath().
This will help consolidating blkg handling by easing moving root blkcg
short-circuit to inlined lookup fast path.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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Each active policy has a cpd (blkcg_policy_data) on each blkcg. The
cpd's were allocated by blkcg core and each policy could request to
allocate extra space at the end by setting blkcg_policy->cpd_size
larger than the size of cpd.
This is a bit unusual but blkg (blkcg_gq) policy data used to be
handled this way too so it made sense to be consistent; however, blkg
policy data switched to alloc/free callbacks.
This patch makes similar changes to cpd handling.
blkcg_policy->cpd_alloc/free_fn() are added to replace ->cpd_size. As
cpd allocation is now done from policy side, it can simply allocate a
larger area which embeds cpd at the beginning.
As ->cpd_alloc_fn() may be able to perform all necessary
initializations, this patch makes ->cpd_init_fn() optional.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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* Rename blkcg->pd[] to blkcg->cpd[] so that cpd is consistently used
for blkcg_policy_data.
* Make blkcg_policy->cpd_init_fn() take blkcg_policy_data instead of
blkcg. This makes it consistent with blkg_policy_data methods and
to-be-added cpd alloc/free methods.
* blkcg_policy_data->blkcg and cpd_to_blkcg() added so that
cpd_init_fn() can determine the associated blkcg from
blkcg_policy_data.
v2: blkcg_policy_data->blkcg initializations were missing. Added.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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The newly added ->pd_alloc_fn() and ->pd_free_fn() deal with pd
(blkg_policy_data) while the older ones use blkg (blkcg_gq). As using
blkg doesn't make sense for ->pd_alloc_fn() and after allocation pd
can always be mapped to blkg and given that these are policy-specific
methods, it makes sense to converge on pd.
This patch makes all methods deal with pd instead of blkg. Most
conversions are trivial. In blk-cgroup.c, a couple method invocation
sites now test whether pd exists instead of policy state for
consistency. This shouldn't cause any behavioral differences.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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With the recent addition of alloc and free methods, things became
messier. This patch reorganizes them according to the followings.
* ->pd_alloc_fn()
Responsible for allocation and static initializations - the ones
which can be done independent of where the pd might be attached.
* ->pd_init_fn()
Initializations which require the knowledge of where the pd is
attached.
* ->pd_free_fn()
The counter part of pd_alloc_fn(). Static de-init and freeing.
This leaves ->pd_exit_fn() without any users. Removed.
While at it, collapse an one liner function throtl_pd_exit(), which
has only one user, into its user.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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Because percpu allocator couldn't do non-blocking allocations,
blk-throttle was forced to implement an ad-hoc asynchronous allocation
mechanism for its percpu stats for cases where blkg's (blkcg_gq's) are
allocated from an IO path without sleepable context.
Now that percpu allocator can handle gfp_mask and blkg_policy_data
alloc / free are handled by policy methods, the ad-hoc asynchronous
allocation mechanism can be replaced with direct allocation from
tg_stats_alloc_fn(). Rit it out.
This ensures that an active throtl_grp always has valid non-NULL
->stats_cpu. Remove checks on it.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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A blkg (blkcg_gq) represents the relationship between a cgroup and
request_queue. Each active policy has a pd (blkg_policy_data) on each
blkg. The pd's were allocated by blkcg core and each policy could
request to allocate extra space at the end by setting
blkcg_policy->pd_size larger than the size of pd.
This is a bit unusual but was done this way mostly to simplify error
handling and all the existing use cases could be handled this way;
however, this is becoming too restrictive now that percpu memory can
be allocated without blocking.
This introduces two new mandatory blkcg_policy methods - pd_alloc_fn()
and pd_free_fn() - which are used to allocate and release pd for a
given policy. As pd allocation is now done from policy side, it can
simply allocate a larger area which embeds pd at the beginning. This
change makes ->pd_size pointless. Removed.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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blkg_create() allows NULL ->pd_init_fn() but blkcg_activate_policy()
doesn't. As both in-kernel policies implement ->pd_init_fn, it
currently doesn't break anything. Update blkcg_activate_policy() so
that its behavior is consistent with blkg_create().
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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When a policy gets activated, it needs to allocate and install its
policy data on all existing blkg's (blkcg_gq's). Because blkg
iteration is protected by a spinlock, it currently counts the total
number of blkg's in the system, allocates the matching number of
policy data on a list and installs them during a single iteration.
This can be simplified by using speculative GFP_NOWAIT allocations
while iterating and falling back to a preallocated policy data on
failure. If the preallocated one has already been consumed, it
releases the lock, preallocate with GFP_KERNEL and then restarts the
iteration. This can be a bit more expensive than before but policy
activation is a very cold path and shouldn't matter.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
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blkcg_css_alloc() bypasses policy data allocation and blkcg_css_free()
bypasses policy data and blkcg freeing for blkcg_root. There's no
reason to to treat policy data any differently for blkcg_root. If the
root css gets allocated after policies are registered, policy
registration path will add policy data; otherwise, the alloc path
will. The free path isn't never invoked for root csses.
This patch removes the unnecessary special handling of blkcg_root from
css_alloc/free paths.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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When blkcg_init_queue() fails midway after creating a new blkg, it
performs kfree() directly; however, this doesn't free the policy data
areas. Make it use blkg_free() instead. In turn, blkg_free() is
updated to handle root request_list special case.
While this fixes a possible memory leak, it's on an unlikely failure
path of an already cold path and the size leaked per occurrence is
miniscule too. I don't think it needs to be tagged for -stable.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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Up until now, all async IOs were queued to async queues which are
shared across the whole request_queue, which means that blkcg resource
control is completely void on async IOs including all writeback IOs.
It was done this way because writeback didn't support writeback and
there was no way of telling which writeback IO belonged to which
cgroup; however, writeback recently became cgroup aware and writeback
bio's are sent down properly tagged with the blkcg's to charge them
against.
This patch makes async cfq_queues per-cfq_cgroup instead of
per-cfq_data so that each async IO is charged to the blkcg that it was
tagged for instead of unconditionally attributing it to root.
* cfq_data->async_cfqq and ->async_idle_cfqq are moved to cfq_group
and alloc / destroy paths are updated accordingly.
* cfq_link_cfqq_cfqg() no longer overrides @cfqg to root for async
queues.
* check_blkcg_changed() now also invalidates async queues as they no
longer stay the same across cgroups.
After this patch, cfq's proportional IO control through blkio.weight
works correctly when cgroup writeback is in use.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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cfq_find_alloc_queue() checks whether a queue actually needs to be
allocated, which is unnecessary as its sole caller, cfq_get_queue(),
only calls it if so. Also, the oom queue fallback logic is scattered
between cfq_get_queue() and cfq_find_alloc_queue(). There really
isn't much going on in the latter and things can be made simpler by
folding it into cfq_get_queue().
This patch collapses cfq_find_alloc_queue() into cfq_get_queue(). The
change is fairly straight-forward with one exception - async_cfqq is
now initialized to NULL and the "!is_sync" test in the last if
conditional is replaced with "async_cfqq" test. This is because gcc
(5.1.1) gets confused for some reason and warns that async_cfqq may be
used uninitialized otherwise. Oh well, the code isn't necessarily
worse this way.
This patch doesn't cause any functional difference.
v2: Updated to reflect GFP_ATOMIC -> GPF_NOWAIT.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
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This is necessary for making async cfq_cgroups per-cfq_group instead
of per-cfq_data. While this change makes cfq_get_queue() perform RCU
locking and look up cfq_group even when it reuses async queue, the
extra overhead is extremely unlikely to be noticeable given that this
is already sitting behind cic->cfqq[] cache and the overall cost of
cfq operation.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
|
|
Even when allocations fail, cfq_find_alloc_queue() always returns a
valid cfq_queue by falling back to the oom cfq_queue. As such, there
isn't much point in taking @gfp_mask and trying "harder" if __GFP_WAIT
is set. GFP_NOWAIT allocations don't fail often and even when they do
the degraded behavior is acceptable and temporary.
After all, the only reason get_request(), which ultimately determines
the gfp_mask, cares about __GFP_WAIT is to guarantee request
allocation, assuming IO forward progress, for callers which are
willing to wait. There's no reason for cfq_find_alloc_queue() to
behave differently on __GFP_WAIT when it already has a fallback
mechanism.
Remove @gfp_mask from cfq_find_alloc_queue() and propagate the changes
to its callers. This simplifies the function quite a bit and will
help making async queues per-cfq_group.
v2: Updated to reflect GFP_ATOMIC -> GPF_NOWAIT.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
|
|
blkcg performs several allocations to track IOs per cgroup and enforce
resource control. Most of these allocations are performed lazily on
demand in the IO path and thus can't involve reclaim path. Currently,
these allocations use GFP_ATOMIC; however, blkcg can gracefully deal
with occassional failures of these allocations by punting IOs to the
root cgroup and there's no reason to reach into the emergency reserve.
This patch replaces GFP_ATOMIC with GFP_NOWAIT for the following
allocations.
* bdi_writeback_congested and blkcg_gq allocations in blkg_create().
* radix tree node allocations for blkcg->blkg_tree.
* cfq_queue allocation on ioprio changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Suggested-and-Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Suggested-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
|
|
* Some were accessing cic->cfqq[] directly. Always use cic_to_cfqq()
and cic_set_cfqq().
* check_ioprio_changed() doesn't need to verify cfq_get_queue()'s
return for NULL. It's always non-NULL. Simplify accordingly.
This patch doesn't cause any functional changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
|
|
If the cfq_queue cached in cfq_io_cq is the oom one, cfq_set_request()
replaces it by invoking cfq_get_queue() again without putting the oom
queue leaking the reference it was holding. While oom queues are not
released through reference counting, they're still reference counted
and this can theoretically lead to the reference count overflowing and
incorrectly invoke the usual release path on it.
Fix it by making cfq_set_request() put the ref it was holding.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
|
|
Async cfqq's (cfq_queue's) are shared across cfq_data. When
cfq_get_queue() obtains a new queue from cfq_find_alloc_queue(), it
stashes the pointer in cfq_data and reuses it from then on; however,
the function doesn't consider that cfq_find_alloc_queue() may return
the oom_cfqq under memory pressure and installs the returned queue
unconditionally.
If the oom_cfqq is installed as an async cfqq, cfq_set_request() will
continue calling cfq_get_queue() hoping to replace it with a proper
queue; however, cfq_get_queue() will keep returning the cached queue
for the slot - the oom_cfqq.
Fix it by skipping caching if the queue is the oom one.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
|
|
cfq_get_queue()'s control flow looks like the following.
async_cfqq = NULL;
cfqq = NULL;
if (!is_sync) {
...
async_cfqq = ...;
cfqq = *async_cfqq;
}
if (!cfqq)
cfqq = ...;
if (!is_sync && !(*async_cfqq))
...;
The only thing the local variable init, the second if, and the
async_cfqq test in the third if achieves is to skip cfqq creation and
installation if *async_cfqq was already non-NULL. This is needlessly
complicated with different tests examining the same condition.
Simplify it to the following.
if (!is_sync) {
...
async_cfqq = ...;
cfqq = *async_cfqq;
if (cfqq)
goto out;
}
cfqq = ...;
if (!is_sync)
...;
out:
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
|
|
This reverts commit 34b48db66e08ca1c1bc07cf305d672ac940268dc.
That commit caused performance regressions for streaming I/O
workloads on a number of different storage devices, from
SATA disks to external RAID arrays. It also managed to
trip up some buggy firmware in at least one drive, causing
data corruption.
The next patch will bump the default max_sectors_kb value to
1280, which will accommodate a 10-data-disk stripe write
with chunk size 128k. In the testing I've done using iozone,
fio, and aio-stress, a value of 1280 does not show a big
performance difference from 512. This will hopefully still
help the software RAID setup that Christoph saw the original
performance gains with while still not regressing other
storage configurations.
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
|
|
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
[hch: split from a larger patch by Dan]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
|
|
Pull SCSI fixes from James Bottomley:
"This has two libfc fixes for bugs causing rare crashes, one iscsi fix
for a potential hang on shutdown, and a fix for an I/O blocksize issue
which caused a regression"
* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
sd: Fix maximum I/O size for BLOCK_PC requests
libfc: Fix fc_fcp_cleanup_each_cmd()
libfc: Fix fc_exch_recv_req() error path
libiscsi: Fix host busy blocking during connection teardown
|
|
Inside timeout handler, blk_mq_tag_to_rq() is called
to retrieve the request from one tag. This way is obviously
wrong because the request can be freed any time and some
fiedds of the request can't be trusted, then kernel oops
might be triggered[1].
Currently wrt. blk_mq_tag_to_rq(), the only special case is
that the flush request can share same tag with the request
cloned from, and the two requests can't be active at the same
time, so this patch fixes the above issue by updating tags->rqs[tag]
with the active request(either flush rq or the request cloned
from) of the tag.
Also blk_mq_tag_to_rq() gets much simplified with this patch.
Given blk_mq_tag_to_rq() is mainly for drivers and the caller must
make sure the request can't be freed, so in bt_for_each() this
helper is replaced with tags->rqs[tag].
[1] kernel oops log
[ 439.696220] BUG: unable to handle kernel NULL pointer dereference at 0000000000000158^M
[ 439.697162] IP: [<ffffffff812d89ba>] blk_mq_tag_to_rq+0x21/0x6e^M
[ 439.700653] PGD 7ef765067 PUD 7ef764067 PMD 0 ^M
[ 439.700653] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC ^M
[ 439.700653] Dumping ftrace buffer:^M
[ 439.700653] (ftrace buffer empty)^M
[ 439.700653] Modules linked in: nbd ipv6 kvm_intel kvm serio_raw^M
[ 439.700653] CPU: 6 PID: 2779 Comm: stress-ng-sigfd Not tainted 4.2.0-rc5-next-20150805+ #265^M
[ 439.730500] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011^M
[ 439.730500] task: ffff880605308000 ti: ffff88060530c000 task.ti: ffff88060530c000^M
[ 439.730500] RIP: 0010:[<ffffffff812d89ba>] [<ffffffff812d89ba>] blk_mq_tag_to_rq+0x21/0x6e^M
[ 439.730500] RSP: 0018:ffff880819203da0 EFLAGS: 00010283^M
[ 439.730500] RAX: ffff880811b0e000 RBX: ffff8800bb465f00 RCX: 0000000000000002^M
[ 439.730500] RDX: 0000000000000000 RSI: 0000000000000202 RDI: 0000000000000000^M
[ 439.730500] RBP: ffff880819203db0 R08: 0000000000000002 R09: 0000000000000000^M
[ 439.730500] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000202^M
[ 439.730500] R13: ffff880814104800 R14: 0000000000000002 R15: ffff880811a2ea00^M
[ 439.730500] FS: 00007f165b3f5740(0000) GS:ffff880819200000(0000) knlGS:0000000000000000^M
[ 439.730500] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b^M
[ 439.730500] CR2: 0000000000000158 CR3: 00000007ef766000 CR4: 00000000000006e0^M
[ 439.730500] Stack:^M
[ 439.730500] 0000000000000008 ffff8808114eed90 ffff880819203e00 ffffffff812dc104^M
[ 439.755663] ffff880819203e40 ffffffff812d9f5e 0000020000000000 ffff8808114eed80^M
[ 439.755663] Call Trace:^M
[ 439.755663] <IRQ> ^M
[ 439.755663] [<ffffffff812dc104>] bt_for_each+0x6e/0xc8^M
[ 439.755663] [<ffffffff812d9f5e>] ? blk_mq_rq_timed_out+0x6a/0x6a^M
[ 439.755663] [<ffffffff812d9f5e>] ? blk_mq_rq_timed_out+0x6a/0x6a^M
[ 439.755663] [<ffffffff812dc1b3>] blk_mq_tag_busy_iter+0x55/0x5e^M
[ 439.755663] [<ffffffff812d88b4>] ? blk_mq_bio_to_request+0x38/0x38^M
[ 439.755663] [<ffffffff812d8911>] blk_mq_rq_timer+0x5d/0xd4^M
[ 439.755663] [<ffffffff810a3e10>] call_timer_fn+0xf7/0x284^M
[ 439.755663] [<ffffffff810a3d1e>] ? call_timer_fn+0x5/0x284^M
[ 439.755663] [<ffffffff812d88b4>] ? blk_mq_bio_to_request+0x38/0x38^M
[ 439.755663] [<ffffffff810a46d6>] run_timer_softirq+0x1ce/0x1f8^M
[ 439.755663] [<ffffffff8104c367>] __do_softirq+0x181/0x3a4^M
[ 439.755663] [<ffffffff8104c76e>] irq_exit+0x40/0x94^M
[ 439.755663] [<ffffffff81031482>] smp_apic_timer_interrupt+0x33/0x3e^M
[ 439.755663] [<ffffffff815559a4>] apic_timer_interrupt+0x84/0x90^M
[ 439.755663] <EOI> ^M
[ 439.755663] [<ffffffff81554350>] ? _raw_spin_unlock_irq+0x32/0x4a^M
[ 439.755663] [<ffffffff8106a98b>] finish_task_switch+0xe0/0x163^M
[ 439.755663] [<ffffffff8106a94d>] ? finish_task_switch+0xa2/0x163^M
[ 439.755663] [<ffffffff81550066>] __schedule+0x469/0x6cd^M
[ 439.755663] [<ffffffff8155039b>] schedule+0x82/0x9a^M
[ 439.789267] [<ffffffff8119b28b>] signalfd_read+0x186/0x49a^M
[ 439.790911] [<ffffffff8106d86a>] ? wake_up_q+0x47/0x47^M
[ 439.790911] [<ffffffff811618c2>] __vfs_read+0x28/0x9f^M
[ 439.790911] [<ffffffff8117a289>] ? __fget_light+0x4d/0x74^M
[ 439.790911] [<ffffffff811620a7>] vfs_read+0x7a/0xc6^M
[ 439.790911] [<ffffffff8116292b>] SyS_read+0x49/0x7f^M
[ 439.790911] [<ffffffff81554c17>] entry_SYSCALL_64_fastpath+0x12/0x6f^M
[ 439.790911] Code: 48 89 e5 e8 a9 b8 e7 ff 5d c3 0f 1f 44 00 00 55 89
f2 48 89 e5 41 54 41 89 f4 53 48 8b 47 60 48 8b 1c d0 48 8b 7b 30 48 8b
53 38 <48> 8b 87 58 01 00 00 48 85 c0 75 09 48 8b 97 88 0c 00 00 eb 10
^M
[ 439.790911] RIP [<ffffffff812d89ba>] blk_mq_tag_to_rq+0x21/0x6e^M
[ 439.790911] RSP <ffff880819203da0>^M
[ 439.790911] CR2: 0000000000000158^M
[ 439.790911] ---[ end trace d40af58949325661 ]---^M
Cc: <stable@vger.kernel.org>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
|
|
There may be lots of pending requests so that the buffer of PAGE_SIZE
can't hold them at all.
One typical example is scsi-mq, the queue depth(.can_queue) of
scsi_host and blk-mq is quite big but scsi_device's queue_depth
is a bit small(.cmd_per_lun), then it is quite easy to have lots
of pending requests in hw queue.
This patch fixes the following warning and the related memory
destruction.
[ 359.025101] fill_read_buffer: blk_mq_hw_sysfs_show+0x0/0x7d returned bad count^M
[ 359.055595] irq event stamp: 15537^M
[ 359.055606] general protection fault: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC ^M
[ 359.055614] Dumping ftrace buffer:^M
[ 359.055660] (ftrace buffer empty)^M
[ 359.055672] Modules linked in: nbd ipv6 kvm_intel kvm serio_raw^M
[ 359.055678] CPU: 4 PID: 21631 Comm: stress-ng-sysfs Not tainted 4.2.0-rc5-next-20150805 #434^M
[ 359.055679] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011^M
[ 359.055682] task: ffff8802161cc000 ti: ffff88021b4a8000 task.ti: ffff88021b4a8000^M
[ 359.055693] RIP: 0010:[<ffffffff811541c5>] [<ffffffff811541c5>] __kmalloc+0xe8/0x152^M
Cc: <stable@vger.kernel.org>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
|
|
We can always fill up the bio now, no need to estimate the possible
size based on queue parameters.
Acked-by: Steven Whitehouse <swhiteho@redhat.com>
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
[hch: rebased and wrote a changelog]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lin <ming.l@ssi.samsung.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
|
|
As generic_make_request() is now able to handle arbitrarily sized bios,
it's no longer necessary for each individual block driver to define its
own ->merge_bvec_fn() callback. Remove every invocation completely.
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Lars Ellenberg <drbd-dev@lists.linbit.com>
Cc: drbd-user@lists.linbit.com
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Yehuda Sadeh <yehuda@inktank.com>
Cc: Sage Weil <sage@inktank.com>
Cc: Alex Elder <elder@kernel.org>
Cc: ceph-devel@vger.kernel.org
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: dm-devel@redhat.com
Cc: Neil Brown <neilb@suse.de>
Cc: linux-raid@vger.kernel.org
Cc: Christoph Hellwig <hch@infradead.org>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Acked-by: NeilBrown <neilb@suse.de> (for the 'md' bits)
Acked-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
[dpark: also remove ->merge_bvec_fn() in dm-thin as well as
dm-era-target, and resolve merge conflicts]
Signed-off-by: Dongsu Park <dpark@posteo.net>
Signed-off-by: Ming Lin <ming.l@ssi.samsung.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
|
|
The split code in blkdev_issue_{discard,write_same} can go away
now that any driver that cares does the split. We have to make
sure bio size doesn't overflow.
For discard, we set max discard sectors to (1<<31)>>9 to ensure
it doesn't overflow bi_size and hopefully it is of the proper
granularity as long as the granularity is a power of two.
Acked-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Ming Lin <ming.l@ssi.samsung.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
|
|
Since generic_make_request() can now handle arbitrary size bios, all we
have to do is make sure the bvec array doesn't overflow.
__bio_add_page() doesn't need to call ->merge_bvec_fn(), where
we can get rid of unnecessary code paths.
Removing the call to ->merge_bvec_fn() is also fine, as no driver that
implements support for BLOCK_PC commands even has a ->merge_bvec_fn()
method.
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
[dpark: rebase and resolve merge conflicts, change a couple of comments,
make bio_add_page() warn once upon a cloned bio.]
Signed-off-by: Dongsu Park <dpark@posteo.net>
Signed-off-by: Ming Lin <ming.l@ssi.samsung.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
|
|
The way the block layer is currently written, it goes to great lengths
to avoid having to split bios; upper layer code (such as bio_add_page())
checks what the underlying device can handle and tries to always create
bios that don't need to be split.
But this approach becomes unwieldy and eventually breaks down with
stacked devices and devices with dynamic limits, and it adds a lot of
complexity. If the block layer could split bios as needed, we could
eliminate a lot of complexity elsewhere - particularly in stacked
drivers. Code that creates bios can then create whatever size bios are
convenient, and more importantly stacked drivers don't have to deal with
both their own bio size limitations and the limitations of the
(potentially multiple) devices underneath them. In the future this will
let us delete merge_bvec_fn and a bunch of other code.
We do this by adding calls to blk_queue_split() to the various
make_request functions that need it - a few can already handle arbitrary
size bios. Note that we add the call _after_ any call to
blk_queue_bounce(); this means that blk_queue_split() and
blk_recalc_rq_segments() don't need to be concerned with bouncing
affecting segment merging.
Some make_request_fn() callbacks were simple enough to audit and verify
they don't need blk_queue_split() calls. The skipped ones are:
* nfhd_make_request (arch/m68k/emu/nfblock.c)
* axon_ram_make_request (arch/powerpc/sysdev/axonram.c)
* simdisk_make_request (arch/xtensa/platforms/iss/simdisk.c)
* brd_make_request (ramdisk - drivers/block/brd.c)
* mtip_submit_request (drivers/block/mtip32xx/mtip32xx.c)
* loop_make_request
* null_queue_bio
* bcache's make_request fns
Some others are almost certainly safe to remove now, but will be left
for future patches.
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Ming Lei <ming.lei@canonical.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: dm-devel@redhat.com
Cc: Lars Ellenberg <drbd-dev@lists.linbit.com>
Cc: drbd-user@lists.linbit.com
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Jim Paris <jim@jtan.com>
Cc: Philip Kelleher <pjk1939@linux.vnet.ibm.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Oleg Drokin <oleg.drokin@intel.com>
Cc: Andreas Dilger <andreas.dilger@intel.com>
Acked-by: NeilBrown <neilb@suse.de> (for the 'md/md.c' bits)
Acked-by: Mike Snitzer <snitzer@redhat.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
[dpark: skip more mq-based drivers, resolve merge conflicts, etc.]
Signed-off-by: Dongsu Park <dpark@posteo.net>
Signed-off-by: Ming Lin <ming.l@ssi.samsung.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
|
|
Commit bcdb247c6b6a ("sd: Limit transfer length") clamped the maximum
size of an I/O request to the MAXIMUM TRANSFER LENGTH field in the BLOCK
LIMITS VPD. This had the unfortunate effect of also limiting the maximum
size of non-filesystem requests sent to the device through sg/bsg.
Avoid using blk_queue_max_hw_sectors() and set the max_sectors queue
limit directly.
Also update the comment in blk_limits_max_hw_sectors() to clarify that
max_hw_sectors defines the limit for the I/O controller only.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Reported-by: Brian King <brking@linux.vnet.ibm.com>
Tested-by: Brian King <brking@linux.vnet.ibm.com>
Cc: stable@vger.kernel.org # 3.17+
Signed-off-by: James Bottomley <JBottomley@Odin.com>
|
|
Some places use helpers now, others don't. We only have the 'is set'
helper, add helpers for setting and clearing flags too.
It was a bit of a mess of atomic vs non-atomic access. With
BIO_UPTODATE gone, we don't have any risk of concurrent access to the
flags. So relax the restriction and don't make any of them atomic. The
flags that do have serialization issues (reffed and chained), we
already handle those separately.
Signed-off-by: Jens Axboe <axboe@fb.com>
|
Tejun Heo
Jeff Moyer
Dan Williams
Linus Torvalds
Ming Lei
Kent Overstreet
Ming Lin
Martin K. Petersen
Jens Axboe