Commit Graph

782127 Commits

Author SHA1 Message Date
Bart Van Assche 986d413b7c blk-mq: Enable support for runtime power management
Now that the blk-mq core processes power management requests
(marked with RQF_PREEMPT) in other states than RPM_ACTIVE, enable
runtime power management for blk-mq.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Jianchao Wang <jianchao.w.wang@oracle.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-26 15:11:29 -06:00
Bart Van Assche 7cedffec8e block: Make blk_get_request() block for non-PM requests while suspended
Instead of allowing requests that are not power management requests
to enter the queue in runtime suspended status (RPM_SUSPENDED), make
the blk_get_request() caller block. This change fixes a starvation
issue: it is now guaranteed that power management requests will be
executed no matter how many blk_get_request() callers are waiting.
For blk-mq, instead of maintaining the q->nr_pending counter, rely
on q->q_usage_counter. Call pm_runtime_mark_last_busy() every time a
request finishes instead of only if the queue depth drops to zero.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Jianchao Wang <jianchao.w.wang@oracle.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-26 15:11:29 -06:00
Bart Van Assche bdd6316094 block: Allow unfreezing of a queue while requests are in progress
A later patch will call blk_freeze_queue_start() followed by
blk_mq_unfreeze_queue() without waiting for q_usage_counter to drop
to zero. Make sure that this doesn't cause a kernel warning to appear
by switching from percpu_ref_reinit() to percpu_ref_resurrect(). The
former namely requires that the refcount it operates on is zero.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Jianchao Wang <jianchao.w.wang@oracle.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-26 15:11:29 -06:00
Bart Van Assche 18c9a6bbe0 percpu-refcount: Introduce percpu_ref_resurrect()
This function will be used in a later patch to switch the struct
request_queue q_usage_counter from killed back to live. In contrast
to percpu_ref_reinit(), this new function does not require that the
refcount is zero.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jianchao Wang <jianchao.w.wang@oracle.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-26 15:11:29 -06:00
Bart Van Assche 0d25bd072b block: Schedule runtime resume earlier
Instead of scheduling runtime resume of a request queue after a
request has been queued, schedule asynchronous resume during request
allocation. The new pm_request_resume() calls occur after
blk_queue_enter() has increased the q_usage_counter request queue
member. This change is needed for a later patch that will make request
allocation block while the queue status is not RPM_ACTIVE.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Jianchao Wang <jianchao.w.wang@oracle.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-26 15:11:28 -06:00
Bart Van Assche 154b00d566 block: Split blk_pm_add_request() and blk_pm_put_request()
Move the pm_request_resume() and pm_runtime_mark_last_busy() calls into
two new functions and thereby separate legacy block layer code from code
that works for both the legacy block layer and blk-mq. A later patch will
add calls to the new functions in the blk-mq code.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Jianchao Wang <jianchao.w.wang@oracle.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-26 15:11:28 -06:00
Bart Van Assche cd84a62e00 block, scsi: Change the preempt-only flag into a counter
The RQF_PREEMPT flag is used for three purposes:
- In the SCSI core, for making sure that power management requests
  are executed even if a device is in the "quiesced" state.
- For domain validation by SCSI drivers that use the parallel port.
- In the IDE driver, for IDE preempt requests.
Rename "preempt-only" into "pm-only" because the primary purpose of
this mode is power management. Since the power management core may
but does not have to resume a runtime suspended device before
performing system-wide suspend and since a later patch will set
"pm-only" mode as long as a block device is runtime suspended, make
it possible to set "pm-only" mode from more than one context. Since
with this change scsi_device_quiesce() is no longer idempotent, make
that function return early if it is called for a quiesced queue.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Cc: Jianchao Wang <jianchao.w.wang@oracle.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-26 15:11:28 -06:00
Bart Van Assche bca6b067b0 block: Move power management code into a new source file
Move the code for runtime power management from blk-core.c into the
new source file blk-pm.c. Move the corresponding declarations from
<linux/blkdev.h> into <linux/blk-pm.h>. For CONFIG_PM=n, leave out
the declarations of the functions that are not used in that mode.
This patch not only reduces the number of #ifdefs in the block layer
core code but also reduces the size of header file <linux/blkdev.h>
and hence should help to reduce the build time of the Linux kernel
if CONFIG_PM is not defined.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Jianchao Wang <jianchao.w.wang@oracle.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-26 15:11:28 -06:00
Christoph Hellwig 3cfa210bf3 xen: don't include <xen/xen.h> from <asm/io.h> and <asm/dma-mapping.h>
Nothing Xen specific in these headers, which get included from a lot
of code in the kernel.  So prune the includes and move them to the
Xen-specific files that actually use them instead.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-26 08:45:18 -06:00
Christoph Hellwig c39ae60dfb block: remove ARCH_BIOVEC_PHYS_MERGEABLE
Take the Xen check into the core code instead of delegating it to
the architectures.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-26 08:45:11 -06:00
Christoph Hellwig 20e3267601 xen: provide a prototype for xen_biovec_phys_mergeable in xen.h
Having multiple externs in arch headers is not a good way to provide
a common interface.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-26 08:45:10 -06:00
Christoph Hellwig cd11b1d344 xen: remove the xen_biovec_phys_mergeable export
BIOVEC_PHYS_MERGEABLE is only called from core block code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-26 08:45:08 -06:00
Christoph Hellwig a5bb207ada arm: remove the unused BIOVEC_MERGEABLE define
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-26 08:45:07 -06:00
Christoph Hellwig 65969e5cb2 block: don't include bug.h from bio.h
No need to pull in the BUG() defintion.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-24 12:34:02 -06:00
Christoph Hellwig bceacbfa48 block: don't include io.h from bio.h
Now that we don't need an override for BIOVEC_PHYS_MERGEABLE there is
no need to drag this header in.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-24 12:34:00 -06:00
Christoph Hellwig 6e768461c2 block: remove bvec_to_phys
We only use it in biovec_phys_mergeable and a m68k paravirt driver,
so just opencode it there.  Also remove the pointless unsigned long cast
for the offset in the opencoded instances.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-24 12:33:59 -06:00
Christoph Hellwig 3dccdae54f block: merge BIOVEC_SEG_BOUNDARY into biovec_phys_mergeable
These two checks should always be performed together, so merge them into
a single helper.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-24 12:33:57 -06:00
Christoph Hellwig 0e253391a9 block: add a missing BIOVEC_SEG_BOUNDARY check in bio_add_pc_page
The actual recaculation of segments in __blk_recalc_rq_segments will
do this check, so there is no point in forcing it if we know it won't
succeed.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-24 12:33:55 -06:00
Christoph Hellwig 6a9f5f240a block: simplify BIOVEC_PHYS_MERGEABLE
Turn the macro into an inline, move it to blk.h and simplify the
arch hooks a bit.

Also rename the function to biovec_phys_mergeable as there is no need
to shout.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-24 12:33:54 -06:00
Christoph Hellwig 27ca1d4ed0 block: move req_gap_back_merge to blk.h
No need to expose these helpers outside the block layer.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-24 12:33:53 -06:00
Christoph Hellwig e9907009cb block: move req_gap_{back,front}_merge to blk-merge.c
Keep it close to the actual users instead of exposing the function to all
drivers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-24 12:33:51 -06:00
Christoph Hellwig 43b729bfe9 block: move integrity_req_gap_{back,front}_merge to blk.h
No need to expose these to drivers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-24 12:33:50 -06:00
Bart Van Assche c7b1bf5cca blk-mq: Document the functions that iterate over requests
Make it easier to understand the purpose of the functions that iterate
over requests by documenting their purpose. Fix several minor spelling
and grammer mistakes in comments in these functions.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Jianchao Wang <jianchao.w.wang@oracle.com>
Cc: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-21 20:30:22 -06:00
Dennis Zhou (Facebook) 101246ec02 blkcg: rename blkg_try_get to blkg_tryget
blkg reference counting now uses percpu_ref rather than atomic_t. Let's
make this consistent with css_tryget. This renames blkg_try_get to
blkg_tryget and now returns a bool rather than the blkg or NULL.

Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-21 20:29:19 -06:00
Dennis Zhou (Facebook) b3b9f24f5f blkcg: change blkg reference counting to use percpu_ref
Now that every bio is associated with a blkg, this puts the use of
blkg_get, blkg_try_get, and blkg_put on the hot path. This switches over
the refcnt in blkg to use percpu_ref.

Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-21 20:29:18 -06:00
Dennis Zhou (Facebook) e2b0989954 blkcg: cleanup and make blk_get_rl use blkg_lookup_create
blk_get_rl is responsible for identifying which request_list a request
should be allocated to. Try get logic was added earlier, but
semantically the logic was not changed.

This patch makes better use of the bio already having a reference to the
blkg in the hot path. The cold path uses a better fallback of
blkg_lookup_create rather than just blkg_lookup and then falling back to
the q->root_rl. If lookup_create fails with anything but -ENODEV, it
falls back to q->root_rl.

A clarifying comment is added to explain why q->root_rl is used rather
than the root blkg's rl.

Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-21 20:29:16 -06:00
Dennis Zhou (Facebook) f0fcb3ec89 blkcg: remove additional reference to the css
The previous patch in this series removed carrying around a pointer to
the css in blkg. However, the blkg association logic still relied on
taking a reference on the css to ensure we wouldn't fail in getting a
reference for the blkg.

Here the implicit dependency on the css is removed. The association
continues to rely on the tryget logic walking up the blkg tree. This
streamlines the three ways that association can happen: normal, swap,
and writeback.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-21 20:29:15 -06:00
Dennis Zhou (Facebook) c839e7a03f blkcg: remove bio->bi_css and instead use bio->bi_blkg
Prior patches ensured that all bios are now associated with some blkg.
This now makes bio->bi_css unnecessary as blkg maintains a reference to
the blkcg already.

This patch removes the field bi_css and transfers corresponding uses to
access via bi_blkg.

Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-21 20:29:13 -06:00
Dennis Zhou (Facebook) bdc2491708 blkcg: associate writeback bios with a blkg
One of the goals of this series is to remove a separate reference to
the css of the bio. This can and should be accessed via bio_blkcg. In
this patch, the wbc_init_bio call is changed such that it must be called
after a queue has been associated with the bio.

Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-21 20:29:11 -06:00
Dennis Zhou (Facebook) 74b7c02a9b blkcg: associate a blkg for pages being evicted by swap
A prior patch in this series added blkg association to bios issued by
cgroups. There are two other paths that we want to attribute work back
to the appropriate cgroup: swap and writeback. Here we modify the way
swap tags bios to include the blkg. Writeback will be tackle in the next
patch.

Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-21 20:29:09 -06:00
Dennis Zhou (Facebook) 5bf9a1f3b4 blkcg: consolidate bio_issue_init to be a part of core
bio_issue_init among other things initializes the timestamp for an IO.
Rather than have this logic handled by policies, this consolidates it to
be on the init paths (normal, clone, bounce clone).

Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Liu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-21 20:29:08 -06:00
Dennis Zhou (Facebook) a7b39b4e96 blkcg: always associate a bio with a blkg
Previously, blkg's were only assigned as needed by blk-iolatency and
blk-throttle. bio->css was also always being associated while blkg was
being looked up and then thrown away in blkcg_bio_issue_check.

This patch begins the cleanup of bio->css and bio->bi_blkg by always
associating a blkg in blkcg_bio_issue_check. This tries to create the
blkg, but if it is not possible, falls back to using the root_blkg of
the request_queue. Therefore, a bio will always be associated with a
blkg. The duplicate association logic is removed from blk-throttle and
blk-iolatency.

Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-21 20:29:06 -06:00
Dennis Zhou (Facebook) 07b05bcc32 blkcg: convert blkg_lookup_create to find closest blkg
There are several scenarios where blkg_lookup_create can fail. Examples
include the blkcg dying, request_queue is dying, or simply being OOM. At
the end of the day, most handle this by simply falling back to the
q->root_blkg and calling it a day.

This patch implements the notion of closest blkg. During
blkg_lookup_create, if it fails to create, return the closest blkg
found or the q->root_blkg. blkg_try_get_closest is introduced and used
during association so a bio is always attached to a blkg.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-21 20:29:05 -06:00
Dennis Zhou (Facebook) 49f4c2dc2b blkcg: update blkg_lookup_create to do locking
To know when to create a blkg, the general pattern is to do a
blkg_lookup and if that fails, lock and then do a lookup again and if
that fails finally create. It doesn't make much sense for everyone who
wants to do creation to write this themselves.

This changes blkg_lookup_create to do locking and implement this
pattern. The old blkg_lookup_create is renamed to __blkg_lookup_create.
If a call site wants to do its own error handling or already owns the
queue lock, they can use __blkg_lookup_create. This will be used in
upcoming patches.

Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Liu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-21 20:29:03 -06:00
Dennis Zhou (Facebook) 27e6fa996c blkcg: fix ref count issue with bio_blkcg using task_css
The accessor function bio_blkcg either returns the blkcg associated with
the bio or finds one in the current context. This can cause an issue
when trying to associate a bio with a blkcg. Particularly, it's the
third case that is problematic:

	return css_to_blkcg(task_css(current, io_cgrp_id));

As the above may race against task migration and the cgroup exiting, it
is not always ok to take a reference on the blkcg returned from
bio_blkcg.

This patch adds association ahead of calling bio_blkcg rather than
after. This makes association a required and explicit step along the
code paths for calling bio_blkcg. blk_get_rl is modified as well to get
a reference to the blkcg it may use and blk_put_rl will always put the
reference back. Association is also moved above the bio_blkcg call to
ensure it will not return NULL in blk-iolatency.

BFQ and CFQ utilize this flaw, but due to the complexity, I do not want
to address this in this series. I've created a private version of the
function with notes not to use it describing the flaw. Hopefully soon,
that code can be cleaned up.

Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-21 20:29:02 -06:00
Liu Bo 9ff01255a0 Blk-throttle: update to use rbtree with leftmost node cached
As rbtree has native support of caching leftmost node,
i.e. rb_root_cached, no need to do the caching by ourselves.

Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-20 19:31:46 -06:00
Christoph Hellwig 576ed91354 block: use bio_add_page in bio_iov_iter_get_pages
Replace a nasty hack with a different nasty hack to prepare for multipage
bio_vecs.  By moving the temporary page array as far up as possible in
the space allocated for the bio_vec array we can iterate forward over it
and thus use bio_add_page.  Using bio_add_page means we'll be able to
merge physically contiguous pages once support for multipath bio_vecs is
merged.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-20 09:11:40 -06:00
Paolo Valente c8765de0ad blok, bfq: do not plug I/O if all queues are weight-raised
To reduce latency for interactive and soft real-time applications, bfq
privileges the bfq_queues containing the I/O of these
applications. These privileged queues, referred-to as weight-raised
queues, get a much higher share of the device throughput
w.r.t. non-privileged queues. To preserve this higher share, the I/O
of any non-weight-raised queue must be plugged whenever a sync
weight-raised queue, while being served, remains temporarily empty. To
attain this goal, bfq simply plugs any I/O (from any queue), if a sync
weight-raised queue remains empty while in service.

Unfortunately, this plugging typically lowers throughput with random
I/O, on devices with internal queueing (because it reduces the filling
level of the internal queues of the device).

This commit addresses this issue by restricting the cases where
plugging is performed: if a sync weight-raised queue remains empty
while in service, then I/O plugging is performed only if some of the
active bfq_queues are *not* weight-raised (which is actually the only
circumstance where plugging is needed to preserve the higher share of
the throughput of weight-raised queues). This restriction proved able
to boost throughput in really many use cases needing only maximum
throughput.

Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-14 13:06:05 -06:00
Paolo Valente d0edc2473b block, bfq: inject other-queue I/O into seeky idle queues on NCQ flash
The Achilles' heel of BFQ is its failing to reach a high throughput
with sync random I/O on flash storage with internal queueing, in case
the processes doing I/O have differentiated weights.

The cause of this failure is as follows. If at least two processes do
sync I/O, and have a different weight from each other, then BFQ plugs
I/O dispatching every time one of these processes, while it is being
served, remains temporarily without pending I/O requests. This
plugging is necessary to guarantee that every process enjoys a
bandwidth proportional to its weight; but it empties the internal
queue(s) of the drive. And this kills throughput with random I/O. So,
if some processes have differentiated weights and do both sync and
random I/O, the end result is a throughput collapse.

This commit tries to counter this problem by injecting the service of
other processes, in a controlled way, while the process in service
happens to have no I/O. This injection is performed only if the medium
is non rotational and performs internal queueing, and the process in
service does random I/O (service injection might be beneficial for
sequential I/O too, we'll work on that).

As an example of the benefits of this commit, on a PLEXTOR PX-256M5S
SSD, and with five processes having differentiated weights and doing
sync random 4KB I/O, this commit makes the throughput with bfq grow by
400%, from 25 to 100MB/s. This higher throughput is 10MB/s lower than
that reached with none. As some less random I/O is added to the mix,
the throughput becomes equal to or higher than that with none.

This commit is a very first attempt to recover throughput without
losing control, and certainly has many limitations. One is, e.g., that
the processes whose service is injected are not chosen so as to
distribute the extra bandwidth they receive in accordance to their
weights. Thus there might be loss of weighted fairness in some
cases. Anyway, this loss concerns extra service, which would not have
been received at all without this commit. Other limitations and issues
will probably show up with usage.

Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-14 13:06:03 -06:00
Paolo Valente cbeb869a3d block, bfq: correctly charge and reset entity service in all cases
BFQ schedules entities (which represent either per-process queues or
groups of queues) as a function of their timestamps. In particular, as
a function of their (virtual) finish times. The finish time of an
entity is computed as a function of the budget assigned to the entity,
assuming, tentatively, that the entity, once in service, will receive
an amount of service equal to its budget. Then, when the entity is
expired because it finishes to be served, this finish time is updated
as a function of the actual service received by the entity. This
allows the entity to be correctly charged with only the service
received, and then to be correctly re-scheduled.

Yet an entity may receive service also while not being the entity in
service (in the scheduling environment of its parent entity), for
several reasons. If the entity remains with no backlog while receiving
this 'unofficial' service, then it is expired. Also on such an
expiration, the finish time of the entity should be updated to account
for only the service actually received by the entity. Unfortunately,
such an update is not performed for an entity expiring without being
the entity in service.

In a similar vein, the service counter of the entity in service is
reset when the entity is expired, to be ready to be used for next
service cycle. This reset too should be performed also in case an
entity is expired because it remains empty after receiving service
while not being the entity in service. But in this case the reset is
not performed.

This commit performs the above update of the finish time and reset of
the service received, also for an entity expiring while not being the
entity in service.

Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-14 13:06:02 -06:00
YueHaibing f8c0d7b16f blk-iolatency: remove set but not used variables 'changed' and 'blkiolat'
Fixes gcc '-Wunused-but-set-variable' warning:

block/blk-iolatency.c: In function 'scale_change':
block/blk-iolatency.c:301:7: warning:
 variable 'changed' set but not used [-Wunused-but-set-variable]

block/blk-iolatency.c: In function 'iolatency_set_limit':
block/blk-iolatency.c:765:24: warning:
 variable 'blkiolat' set but not used [-Wunused-but-set-variable]

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-13 19:59:24 -06:00
Nathan Chancellor 798ef9e701 rsxx: Remove unnecessary parentheses
Clang warns when more than one set of parentheses is used for a
single conditional statement:

drivers/block/rsxx/cregs.c:279:15: warning: equality comparison with
extraneous parentheses [-Wparentheses-equality]
        if ((cmd->op == CREG_OP_READ)) {
             ~~~~~~~~^~~~~~~~~~~~~~~
drivers/block/rsxx/cregs.c:279:15: note: remove extraneous parentheses
around the comparison to silence this warning
        if ((cmd->op == CREG_OP_READ)) {
            ~        ^              ~
drivers/block/rsxx/cregs.c:279:15: note: use '=' to turn this equality
comparison into an assignment
        if ((cmd->op == CREG_OP_READ)) {
                     ^~
                     =
1 warning generated.

Reported-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-11 16:56:39 -06:00
jun qian 902d53914f block: umem: replace spin_lock_bh with spin_lock in tasklet callback
As you are already in a tasklet, it is unnecessary to call spin_lock_bh.

Signed-off-by: jun qian <hangdianqj@163.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-07 11:34:24 -06:00
Ming Lei 7759eb23fd block: remove bio_rewind_iter()
It is pointed that bio_rewind_iter() is one very bad API[1]:

1) bio size may not be restored after rewinding

2) it causes some bogus change, such as 5151842b9d (block: reset
bi_iter.bi_done after splitting bio)

3) rewinding really makes things complicated wrt. bio splitting

4) unnecessary updating of .bi_done in fast path

[1] https://marc.info/?t=153549924200005&r=1&w=2

So this patch takes Kent's suggestion to restore one bio into its original
state via saving bio iterator(struct bvec_iter) in bio_integrity_prep(),
given now bio_rewind_iter() is only used by bio integrity code.

Cc: Dmitry Monakhov <dmonakhov@openvz.org>
Cc: Hannes Reinecke <hare@suse.com>
Suggested-by: Kent Overstreet <kent.overstreet@gmail.com>
Acked-by: Kent Overstreet <kent.overstreet@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-06 15:12:24 -06:00
Kees Cook 3d0e63754f drbd: Convert from ahash to shash
In preparing to remove all stack VLA usage from the kernel[1], this
removes the discouraged use of AHASH_REQUEST_ON_STACK in favor of
the smaller SHASH_DESC_ON_STACK by converting from ahash-wrapped-shash
to direct shash. By removing a layer of indirection this both improves
performance and reduces stack usage. The stack allocation will be made
a fixed size in a later patch to the crypto subsystem.

The bulk of the lines in this change are simple s/ahash/shash/, but the
main logic differences are in drbd_csum_ee() and drbd_csum_bio(), which
externalizes the page walking with k(un)map_atomic() instead of using
scattergather.

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com

Acked-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-06 15:12:24 -06:00
Linus Torvalds ca16eb342e for-linus-20180906
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Merge tag 'for-linus-20180906' of git://git.kernel.dk/linux-block

Pull block fixes from Jens Axboe:
 "Small collection of fixes that should go into this release. This
  contains:

   - Small series that fixes a race between blkcg teardown and writeback
     (Dennis Zhou)

   - Fix disallowing invalid block size settings from the nbd ioctl (me)

   - BFQ fix for a use-after-free on last release of a bfqg (Konstantin
     Khlebnikov)

   - Fix for the "don't warn for flush" fix (Mikulas)"

* tag 'for-linus-20180906' of git://git.kernel.dk/linux-block:
  block: bfq: swap puts in bfqg_and_blkg_put
  block: don't warn when doing fsync on read-only devices
  nbd: don't allow invalid blocksize settings
  blkcg: use tryget logic when associating a blkg with a bio
  blkcg: delay blkg destruction until after writeback has finished
  Revert "blk-throttle: fix race between blkcg_bio_issue_check() and cgroup_rmdir()"
2018-09-06 14:01:15 -07:00
Konstantin Khlebnikov d5274b3cd6 block: bfq: swap puts in bfqg_and_blkg_put
Fix trivial use-after-free. This could be last reference to bfqg.

Fixes: 8f9bebc33d ("block, bfq: access and cache blkg data only when safe")
Acked-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-06 11:32:58 -06:00
Linus Torvalds db44bf4b47 - Fix for bad debug check when converting secids to secctx
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Merge tag 'apparmor-pr-2018-09-06' of git://git.kernel.org/pub/scm/linux/kernel/git/jj/linux-apparmor

Pull apparmor fix from John Johansen:
 "A fix for an issue syzbot discovered last week:

   - Fix for bad debug check when converting secids to secctx"

* tag 'apparmor-pr-2018-09-06' of git://git.kernel.org/pub/scm/linux/kernel/git/jj/linux-apparmor:
  apparmor: fix bad debug check in apparmor_secid_to_secctx()
2018-09-06 09:42:14 -07:00
Linus Torvalds be65e2595b This fixes two bugs:
- The first one is a side effect caused by using SRCU for rcuidle
    tracepoints. It seems that the perf was depending on the rcuidle
    tracepoints to make RCU watch when it wasn't. The real fix will
    bet to have perf use SRCU instead of depending on RCU watching,
    but that can't be done until SRCU is safe to use in NMI context
    (Paul's working on that).
 
  - The second bug fix is for a bug that's been periodically making
    my tests fail randomly for some time. I haven't had time to track
    it down, but finally have. It has to do with stressing NMIs (via perf)
    while enabling or disabling ftrace function handling with lockdep
    enabled. If an interrupt happens and just as it returns, it sets
    lockdep back to "interrupts enabled" but before it returns an NMI
    is triggered, and if this happens while printk_nmi_enter has a
    breakpoint attached to it (because ftrace is converting it to or from
    nop to call fentry), the breakpoint trap also calls into lockdep,
    and since returning from the NMI to a interrupt handler, interrupts
    were disabled when the NMI went off, lockdep keeps its state as
    interrupts disabled when it returns back from the interrupt handler
    where interrupts are enabled. This causes lockdep_assert_irqs_enabled()
    to trigger a false positive.
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Merge tag 'trace-v4.19-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing fixes from Steven Rostedt:
 "This fixes two annoying bugs:

   - The first one is a side effect caused by using SRCU for rcuidle
     tracepoints. It seems that the perf was depending on the rcuidle
     tracepoints to make RCU watch when it wasn't.

     The real fix will be to have perf use SRCU instead of depending on
     RCU watching, but that can't be done until SRCU is safe to use in
     NMI context (Paul's working on that).

   - The second bug fix is for a bug that's been periodically making my
     tests fail randomly for some time. I haven't had time to track it
     down, but finally have. It has to do with stressing NMIs (via perf)
     while enabling or disabling ftrace function handling with lockdep
     enabled.

     If an interrupt happens and just as it returns, it sets lockdep
     back to "interrupts enabled" but before it returns an NMI is
     triggered, and if this happens while printk_nmi_enter has a
     breakpoint attached to it (because ftrace is converting it to or
     from nop to call fentry), the breakpoint trap also calls into
     lockdep, and since returning from the NMI to a interrupt handler,
     interrupts were disabled when the NMI went off, lockdep keeps its
     state as interrupts disabled when it returns back from the
     interrupt handler where interrupts are enabled.

     This causes lockdep_assert_irqs_enabled() to trigger a false
     positive"

* tag 'trace-v4.19-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  printk/tracing: Do not trace printk_nmi_enter()
  tracing: Add back in rcu_irq_enter/exit_irqson() for rcuidle tracepoints
2018-09-06 09:06:49 -07:00
Linus Torvalds 5404525b98 for-4.19-rc2-tag
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Merge tag 'for-4.19-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

Pull btrfs fixes from David Sterba:

 - fix for improper fsync after hardlink

 - fix for a corruption during file deduplication

 - use after free fixes

 - RCU warning fix

 - fix for buffered write to nodatacow file

* tag 'for-4.19-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  btrfs: Fix suspicious RCU usage warning in btrfs_debug_in_rcu
  btrfs: use after free in btrfs_quota_enable
  btrfs: btrfs_shrink_device should call commit transaction at the end
  btrfs: fix qgroup_free wrong num_bytes in btrfs_subvolume_reserve_metadata
  Btrfs: fix data corruption when deduplicating between different files
  Btrfs: sync log after logging new name
  Btrfs: fix unexpected failure of nocow buffered writes after snapshotting when low on space
2018-09-06 09:04:45 -07:00