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2018-11-30sbitmap: optimize wakeup checkJens Axboe1-6/+5
Even if we have no waiters on any of the sbitmap_queue wait states, we still have to loop every entry to check. We do this for every IO, so the cost adds up. Shift a bit of the cost to the slow path, when we actually have waiters. Wrap prepare_to_wait_exclusive() and finish_wait(), so we can maintain an internal count of how many are currently active. Then we can simply check this count in sbq_wake_ptr() and not have to loop if we don't have any sleepers. Convert the two users of sbitmap with waiting, blk-mq-tag and iSCSI. Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-08blk-mq-tag: document tag iteration helper return valueJens Axboe1-4/+8
Document the fact that the strategy function passed in can control whether to continue iterating or not. Suggested-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-08blk-mq-tag: change busy_iter_fn to return whether to continue or notJens Axboe1-2/+2
We have this functionality in sbitmap, but we don't export it in blk-mq for users of the tags busy iteration. This can be useful for stopping the iteration, if the caller doesn't need to find more requests. Reviewed-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07blk-mq: cache request hardware queue mappingJens Axboe1-8/+1
We call blk_mq_map_queue() a lot, at least two times for each request per IO, sometimes more. Since we now have an indirect call as well in that function. cache the mapping so we don't have to re-call blk_mq_map_queue() for the same request multiple times. Reviewed-by: Keith Busch <keith.busch@intel.com> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07blk-mq: pass in request/bio flags to queue mappingJens Axboe1-2/+3
Prep patch for being able to place request based not just on CPU location, but also on the type of request. Reviewed-by: Hannes Reinecke <hare@suse.com> Reviewed-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07block: remove legacy rq taggingJens Axboe1-4/+2
It's now unused, kill it. Reviewed-by: Hannes Reinecke <hare@suse.com> Tested-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-10-01Merge tag 'v4.19-rc6' into for-4.20/blockJens Axboe1-5/+2
Merge -rc6 in, for two reasons: 1) Resolve a trivial conflict in the blk-mq-tag.c documentation 2) A few important regression fixes went into upstream directly, so they aren't in the 4.20 branch. Signed-off-by: Jens Axboe <axboe@kernel.dk> * tag 'v4.19-rc6': (780 commits) Linux 4.19-rc6 MAINTAINERS: fix reference to moved drivers/{misc => auxdisplay}/panel.c cpufreq: qcom-kryo: Fix section annotations perf/core: Add sanity check to deal with pinned event failure xen/blkfront: correct purging of persistent grants Revert "xen/blkfront: When purging persistent grants, keep them in the buffer" selftests/powerpc: Fix Makefiles for headers_install change blk-mq: I/O and timer unplugs are inverted in blktrace dax: Fix deadlock in dax_lock_mapping_entry() x86/boot: Fix kexec booting failure in the SEV bit detection code bcache: add separate workqueue for journal_write to avoid deadlock drm/amd/display: Fix Edid emulation for linux drm/amd/display: Fix Vega10 lightup on S3 resume drm/amdgpu: Fix vce work queue was not cancelled when suspend Revert "drm/panel: Add device_link from panel device to DRM device" xen/blkfront: When purging persistent grants, keep them in the buffer clocksource/drivers/timer-atmel-pit: Properly handle error cases block: fix deadline elevator drain for zoned block devices ACPI / hotplug / PCI: Don't scan for non-hotplug bridges if slot is not bridge drm/syncobj: Don't leak fences when WAIT_FOR_SUBMIT is set ... Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-25blk-mq: Allow blocking queue tag iter callbacksKeith Busch1-9/+4
A recent commit runs tag iterator callbacks under the rcu read lock, but existing callbacks do not satisfy the non-blocking requirement. The commit intended to prevent an iterator from accessing a queue that's being modified. This patch fixes the original issue by taking a queue reference instead of reading it, which allows callbacks to make blocking calls. Fixes: f5bbbbe4d6357 ("blk-mq: sync the update nr_hw_queues with blk_mq_queue_tag_busy_iter") Acked-by: Jianchao Wang <jianchao.w.wang@oracle.com> Signed-off-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-21blk-mq: Document the functions that iterate over requestsBart Van Assche1-7/+64
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>
2018-08-22Merge tag 'for-4.19/post-20180822' of git://git.kernel.dk/linux-blockLinus Torvalds1-1/+13
Pull more block updates from Jens Axboe: - Set of bcache fixes and changes (Coly) - The flush warn fix (me) - Small series of BFQ fixes (Paolo) - wbt hang fix (Ming) - blktrace fix (Steven) - blk-mq hardware queue count update fix (Jianchao) - Various little fixes * tag 'for-4.19/post-20180822' of git://git.kernel.dk/linux-block: (31 commits) block/DAC960.c: make some arrays static const, shrinks object size blk-mq: sync the update nr_hw_queues with blk_mq_queue_tag_busy_iter blk-mq: init hctx sched after update ctx and hctx mapping block: remove duplicate initialization tracing/blktrace: Fix to allow setting same value pktcdvd: fix setting of 'ret' error return for a few cases block: change return type to bool block, bfq: return nbytes and not zero from struct cftype .write() method block, bfq: improve code of bfq_bfqq_charge_time block, bfq: reduce write overcharge block, bfq: always update the budget of an entity when needed block, bfq: readd missing reset of parent-entity service blk-wbt: fix IO hang in wbt_wait() block: don't warn for flush on read-only device bcache: add the missing comments for smp_mb()/smp_wmb() bcache: remove unnecessary space before ioctl function pointer arguments bcache: add missing SPDX header bcache: move open brace at end of function definitions to next line bcache: add static const prefix to char * array declarations bcache: fix code comments style ...
2018-08-21blk-mq: sync the update nr_hw_queues with blk_mq_queue_tag_busy_iterJianchao Wang1-1/+13
For blk-mq, part_in_flight/rw will invoke blk_mq_in_flight/rw to account the inflight requests. It will access the queue_hw_ctx and nr_hw_queues w/o any protection. When updating nr_hw_queues and blk_mq_in_flight/rw occur concurrently, panic comes up. Before update nr_hw_queues, the q will be frozen. So we could use q_usage_counter to avoid the race. percpu_ref_is_zero is used here so that we will not miss any in-flight request. The access to nr_hw_queues and queue_hw_ctx in blk_mq_queue_tag_busy_iter are under rcu critical section, __blk_mq_update_nr_hw_queues could use synchronize_rcu to ensure the zeroed q_usage_counter to be globally visible. Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-08-14Merge tag 'for-4.19/block-20180812' of git://git.kernel.dk/linux-blockLinus Torvalds1-4/+7
Pull block updates from Jens Axboe: "First pull request for this merge window, there will also be a followup request with some stragglers. This pull request contains: - Fix for a thundering heard issue in the wbt block code (Anchal Agarwal) - A few NVMe pull requests: * Improved tracepoints (Keith) * Larger inline data support for RDMA (Steve Wise) * RDMA setup/teardown fixes (Sagi) * Effects log suppor for NVMe target (Chaitanya Kulkarni) * Buffered IO suppor for NVMe target (Chaitanya Kulkarni) * TP4004 (ANA) support (Christoph) * Various NVMe fixes - Block io-latency controller support. Much needed support for properly containing block devices. (Josef) - Series improving how we handle sense information on the stack (Kees) - Lightnvm fixes and updates/improvements (Mathias/Javier et al) - Zoned device support for null_blk (Matias) - AIX partition fixes (Mauricio Faria de Oliveira) - DIF checksum code made generic (Max Gurtovoy) - Add support for discard in iostats (Michael Callahan / Tejun) - Set of updates for BFQ (Paolo) - Removal of async write support for bsg (Christoph) - Bio page dirtying and clone fixups (Christoph) - Set of bcache fix/changes (via Coly) - Series improving blk-mq queue setup/teardown speed (Ming) - Series improving merging performance on blk-mq (Ming) - Lots of other fixes and cleanups from a slew of folks" * tag 'for-4.19/block-20180812' of git://git.kernel.dk/linux-block: (190 commits) blkcg: Make blkg_root_lookup() work for queues in bypass mode bcache: fix error setting writeback_rate through sysfs interface null_blk: add lock drop/acquire annotation Blk-throttle: reduce tail io latency when iops limit is enforced block: paride: pd: mark expected switch fall-throughs block: Ensure that a request queue is dissociated from the cgroup controller block: Introduce blk_exit_queue() blkcg: Introduce blkg_root_lookup() block: Remove two superfluous #include directives blk-mq: count the hctx as active before allocating tag block: bvec_nr_vecs() returns value for wrong slab bcache: trivial - remove tailing backslash in macro BTREE_FLAG bcache: make the pr_err statement used for ENOENT only in sysfs_attatch section bcache: set max writeback rate when I/O request is idle bcache: add code comments for bset.c bcache: fix mistaken comments in request.c bcache: fix mistaken code comments in bcache.h bcache: add a comment in super.c bcache: avoid unncessary cache prefetch bch_btree_node_get() bcache: display rate debug parameters to 0 when writeback is not running ...
2018-08-09blk-mq: count the hctx as active before allocating tagJianchao Wang1-0/+3
Currently, we count the hctx as active after allocate driver tag successfully. If a previously inactive hctx try to get tag first time, it may fails and need to wait. However, due to the stale tag ->active_queues, the other shared-tags users are still able to occupy all driver tags while there is someone waiting for tag. Consequently, even if the previously inactive hctx is waked up, it still may not be able to get a tag and could be starved. To fix it, we count the hctx as active before try to allocate driver tag, then when it is waiting the tag, the other shared-tag users will reserve budget for it. Reviewed-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-08-02blk-mq: fix blk_mq_tagset_busy_iterMing Lei1-1/+1
Commit d250bf4e776ff09d5("blk-mq: only iterate over inflight requests in blk_mq_tagset_busy_iter") uses 'blk_mq_rq_state(rq) == MQ_RQ_IN_FLIGHT' to replace 'blk_mq_request_started(req)', this way is wrong, and causes lots of test system hang during booting. Fix the issue by using blk_mq_request_started(req) inside bt_tags_iter(). Fixes: d250bf4e776ff09d5 ("blk-mq: only iterate over inflight requests in blk_mq_tagset_busy_iter") Cc: Josef Bacik <josef@toxicpanda.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Guenter Roeck <linux@roeck-us.net> Cc: Mark Brown <broonie@kernel.org> Cc: Matt Hart <matthew.hart@linaro.org> Cc: Johannes Thumshirn <jthumshirn@suse.de> Cc: John Garry <john.garry@huawei.com> Cc: Hannes Reinecke <hare@suse.com>, Cc: "Martin K. Petersen" <martin.petersen@oracle.com>, Cc: James Bottomley <James.Bottomley@hansenpartnership.com> Cc: linux-scsi@vger.kernel.org Cc: linux-kernel@vger.kernel.org Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com> Tested-by: Guenter Roeck <linux@roeck-us.net> Reported-by: Mark Brown <broonie@kernel.org> Reported-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-08-02blk-mq: fix updating tags depthMing Lei1-4/+4
The passed 'nr' from userspace represents the total depth, meantime inside 'struct blk_mq_tags', 'nr_tags' stores the total tag depth, and 'nr_reserved_tags' stores the reserved part. There are two issues in blk_mq_tag_update_depth() now: 1) for growing tags, we should have used the passed 'nr', and keep the number of reserved tags not changed. 2) the passed 'nr' should have been used for checking against 'tags->nr_tags', instead of number of the normal part. This patch fixes the above two cases, and avoids kernel crash caused by wrong resizing sbitmap queue. Cc: "Ewan D. Milne" <emilne@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Bart Van Assche <bart.vanassche@sandisk.com> Cc: Omar Sandoval <osandov@fb.com> Tested by: Marco Patalano <mpatalan@redhat.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-06-14blk-mq: remove blk_mq_tagset_iterChristoph Hellwig1-29/+0
Unused now that nvme stopped using it. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jens Axboe <axboe@kernel.dk>
2018-05-30blk-mq: only iterate over inflight requests in blk_mq_tagset_busy_iterChristoph Hellwig1-1/+1
We already check for started commands in all callbacks, but we should also protect against already completed commands. Do this by taking the checks to common code. Acked-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-05-24blk-mq: avoid starving tag allocation after allocating process migratesMing Lei1-0/+12
When the allocation process is scheduled back and the mapped hw queue is changed, fake one extra wake up on previous queue for compensating wake up miss, so other allocations on the previous queue won't be starved. This patch fixes one request allocation hang issue, which can be triggered easily in case of very low nr_request. The race is as follows: 1) 2 hw queues, nr_requests are 2, and wake_batch is one 2) there are 3 waiters on hw queue 0 3) two in-flight requests in hw queue 0 are completed, and only two waiters of 3 are waken up because of wake_batch, but both the two waiters can be scheduled to another CPU and cause to switch to hw queue 1 4) then the 3rd waiter will wait for ever, since no in-flight request is in hw queue 0 any more. 5) this patch fixes it by the fake wakeup when waiter is scheduled to another hw queue Cc: <stable@vger.kernel.org> Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Modified commit message to make it clearer, and make it apply on top of the 4.18 branch. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-12-22blk-mq: improve heavily contended tag caseJens Axboe1-6/+7
Even with a number of waitqueues, we can get into a situation where we are heavily contended on the waitqueue lock. I got a report on spc1 where we're spending seconds doing this. Arguably the use case is nasty, I reproduce it with one device and 1000 threads banging on the device. But that doesn't mean we shouldn't be handling it better. What ends up happening is that a thread will fail to get a tag, add itself to the waitqueue, and subsequently get woken up when a tag is freed - only to find itself going back to sleep on the waitqueue. Instead of waking all threads, use an exclusive wait and wake up our sbitmap batch count instead. This seems to work well for me (massive improvement for this use case), and it survives basic testing. But I haven't fully verified it yet. An additional improvement is running the queue and checking for a new tag BEFORE needing to add ourselves to the waitqueue. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-10-18block: remove blk_mq_reinit_tagsetSagi Grimberg1-7/+0
No callers left. Reviewed-by: Jens Axboe <axboe@kernel.dk> Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com> Reviewed-by: Max Gurtovoy <maxg@mellanox.com> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: Christoph Hellwig <hch@lst.de>
2017-10-18block: introduce blk_mq_tagset_iterSagi Grimberg1-5/+11
Iterator helper to apply a function on all the tags in a given tagset. export it as it will be used outside the block layer later on. Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com> Reviewed-by: Jens Axboe <axboe@kernel.dk> Reviewed-by: Max Gurtovoy <maxg@mellanox.com> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: Christoph Hellwig <hch@lst.de>
2017-08-18blk-mq: Make blk_mq_reinit_tagset() calls easier to readBart Van Assche1-4/+5
Since blk_mq_ops.reinit_request is only called from inside blk_mq_reinit_tagset(), make this function pointer an argument of blk_mq_reinit_tagset() instead of a member of struct blk_mq_ops. This patch does not change any functionality but makes blk_mq_reinit_tagset() calls easier to read and to analyze. Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com> Reviewed-by: Hannes Reinecke <hare@suse.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Sagi Grimberg <sagi@grimberg.me> Cc: James Smart <james.smart@broadcom.com> Cc: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-08-09blk-mq-tag: check for NULL rq when iterating tagsJens Axboe1-2/+12
Since we introduced blk-mq-sched, the tags->rqs[] array has been dynamically assigned. So we need to check for NULL when iterating, since there's a window of time where the bit is set, but we haven't dynamically assigned the tags->rqs[] array position yet. This is perfectly safe, since the memory backing of the request is never going away while the device is alive. Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com> Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-04-14blk-mq: add shallow depth option for blk_mq_get_tag()Omar Sandoval1-1/+4
Wire up the sbitmap_get_shallow() operation to the tag code so that a caller can limit the number of tags available to it. Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-03-13blk-mq: Fix tagset reinit in the presence of cpu hot-unplugSagi Grimberg1-0/+3
In case cpu was unplugged, we need to make sure not to assume that the tags for that cpu are still allocated. so check for null tags when reinitializing a tagset. Reported-by: Yi Zhang <yizhan@redhat.com> Signed-off-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-03-02blk-mq-sched: Allocate sched reserved tags as specified in the original queue tagsetSagi Grimberg1-1/+1
Signed-off-by: Sagi Grimberg <sagi@grimberg.me> Modified by me to also check at driver tag allocation time if the original request was reserved, so we can be sure to allocate a properly reserved tag at that point in time, too. Signed-off-by: Jens Axboe <axboe@fb.com>
2017-01-27blk-mq-sched: add flush insertion into blk_mq_sched_insert_request()Jens Axboe1-1/+7
Instead of letting the caller check this and handle the details of inserting a flush request, put the logic in the scheduler insertion function. This fixes direct flush insertion outside of the usual make_request_fn calls, like from dm via blk_insert_cloned_request(). Signed-off-by: Jens Axboe <axboe@fb.com>
2017-01-27blk-mq: move tags and sched_tags info from sysfs to debugfsOmar Sandoval1-27/+0
These are very tied to the blk-mq tag implementation, so exposing them to sysfs isn't a great idea. Move the debugging information to debugfs and add basic entries for the number of tags and the number of reserved tags to sysfs. Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-01-25blk-mq: only apply active queue tag throttling for driver tagsJens Axboe1-5/+7
If we have a scheduler attached, we have two sets of tags. We don't want to apply our active queue throttling for the scheduler side of tags, that only applies to driver tags since that's the resource we need to dispatch an IO. Signed-off-by: Jens Axboe <axboe@fb.com>
2017-01-20blk-mq: allow resize of scheduler requestsJens Axboe1-7/+44
Add support for growing the tags associated with a hardware queue, for the scheduler tags. Currently we only support resizing within the limits of the original depth, change that so we can grow it as well by allocating and replacing the existing scheduler tag set. This is similar to how we could increase the software queue depth with the legacy IO stack and schedulers. Signed-off-by: Jens Axboe <axboe@fb.com> Reviewed-by: Omar Sandoval <osandov@fb.com>
2017-01-19blk-mq-tag: remove redundant check for 'data->hctx' being non-NULLJens Axboe1-4/+2
We used to pass in NULL for hctx for reserved tags, but we don't do that anymore. Hence the check for whether hctx is NULL or not is now redundant, kill it. Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Fixes: a642a158aec6 ("blk-mq-tag: cleanup the normal/reserved tag allocation") Signed-off-by: Jens Axboe <axboe@fb.com>
2017-01-17blk-mq: split tag ->rqs[] into twoJens Axboe1-2/+2
This is in preparation for having two sets of tags available. For that we need a static index, and a dynamically assignable one. Signed-off-by: Jens Axboe <axboe@fb.com> Reviewed-by: Omar Sandoval <osandov@fb.com>
2017-01-17blk-mq-tag: cleanup the normal/reserved tag allocationJens Axboe1-58/+36
This is in preparation for having another tag set available. Cleanup the parameters, and allow passing in of tags for blk_mq_put_tag(). Signed-off-by: Jens Axboe <axboe@fb.com> [hch: even more cleanups] Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Omar Sandoval <osandov@fb.com>
2016-10-09Merge branch 'for-4.9/block-irq' of git://git.kernel.dk/linux-blockLinus Torvalds1-9/+2
Pull blk-mq irq/cpu mapping updates from Jens Axboe: "This is the block-irq topic branch for 4.9-rc. It's mostly from Christoph, and it allows drivers to specify their own mappings, and more importantly, to share the blk-mq mappings with the IRQ affinity mappings. It's a good step towards making this work better out of the box" * 'for-4.9/block-irq' of git://git.kernel.dk/linux-block: blk_mq: linux/blk-mq.h does not include all the headers it depends on blk-mq: kill unused blk_mq_create_mq_map() blk-mq: get rid of the cpumask in struct blk_mq_tags nvme: remove the post_scan callout nvme: switch to use pci_alloc_irq_vectors blk-mq: provide a default queue mapping for PCI device blk-mq: allow the driver to pass in a queue mapping blk-mq: remove ->map_queue blk-mq: only allocate a single mq_map per tag_set blk-mq: don't redistribute hardware queues on a CPU hotplug event
2016-09-17sbitmap: randomize initial alloc_hint valuesOmar Sandoval1-8/+0
In order to get good cache behavior from a sbitmap, we want each CPU to stick to its own cacheline(s) as much as possible. This might happen naturally as the bitmap gets filled up and the alloc_hint values spread out, but we really want this behavior from the start. blk-mq apparently intended to do this, but the code to do this was never wired up. Get rid of the dead code and make it part of the sbitmap library. Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-09-17sbitmap: push alloc policy into sbitmap_queueOmar Sandoval1-18/+15
Again, there's no point in passing this in every time. Make it part of struct sbitmap_queue and clean up the API. Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-09-17sbitmap: push per-cpu last_tag into sbitmap_queueOmar Sandoval1-36/+17
Allocating your own per-cpu allocation hint separately makes for an awkward API. Instead, allocate the per-cpu hint as part of the struct sbitmap_queue. There's no point for a struct sbitmap_queue without the cache, but you can still use a bare struct sbitmap. Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-09-17blk-mq: abstract tag allocation out into sbitmap libraryOmar Sandoval1-353/+110
This is a generally useful data structure, so make it available to anyone else who might want to use it. It's also a nice cleanup separating the allocation logic from the rest of the tag handling logic. The code is behind a new Kconfig option, CONFIG_SBITMAP, which is only selected by CONFIG_BLOCK for now. This should be a complete noop functionality-wise. Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-09-15blk-mq: get rid of the cpumask in struct blk_mq_tagsChristoph Hellwig1-6/+0
Unused now that NVMe sets up irq affinity before calling into blk-mq. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-09-15blk-mq: remove ->map_queueChristoph Hellwig1-3/+2
All drivers use the default, so provide an inline version of it. If we ever need other queue mapping we can add an optional method back, although supporting will also require major changes to the queue setup code. This provides better code generation, and better debugability as well. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-07-08blk-mq: Introduce blk_mq_reinit_tagsetSagi Grimberg1-0/+26
The new nvme-rdma driver will need to reinitialize all the tags as part of the error recovery procedure (realloc the tag memory region). Add a helper in blk-mq for it that can iterate over all requests in a tagset to make this easier. Signed-off-by: Sagi Grimberg <sagi@grimberg.me> Tested-by: Ming Lin <ming.l@ssi.samsung.com> Reviewed-by: Stephen Bates <Stephen.Bates@pmcs.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Steve Wise <swise@opengridcomputing.com> Tested-by: Steve Wise <swise@opengridcomputing.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-04-12blk-mq: Make blk_mq_all_tag_busy_iter staticSagi Grimberg1-3/+2
No caller outside the blk-mq code so we can settle with it static. Signed-off-by: Sagi Grimberg <sagig@mellanox.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-04-12blk-mq: Export tagset iter functionSagi Grimberg1-0/+12
Its useful to iterate on all the active tags in cases where we will need to fail all the queues IO. Signed-off-by: Sagi Grimberg <sagig@mellanox.com> [hch: carefully check for valid tagsets] Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-12-01blk-mq: add a flags parameter to blk_mq_alloc_requestChristoph Hellwig1-6/+5
We already have the reserved flag, and a nowait flag awkwardly encoded as a gfp_t. Add a real flags argument to make the scheme more extensible and allow for a nicer calling convention. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-11-06mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapdMel Gorman1-1/+1
__GFP_WAIT has been used to identify atomic context in callers that hold spinlocks or are in interrupts. They are expected to be high priority and have access one of two watermarks lower than "min" which can be referred to as the "atomic reserve". __GFP_HIGH users get access to the first lower watermark and can be called the "high priority reserve". Over time, callers had a requirement to not block when fallback options were available. Some have abused __GFP_WAIT leading to a situation where an optimisitic allocation with a fallback option can access atomic reserves. This patch uses __GFP_ATOMIC to identify callers that are truely atomic, cannot sleep and have no alternative. High priority users continue to use __GFP_HIGH. __GFP_DIRECT_RECLAIM identifies callers that can sleep and are willing to enter direct reclaim. __GFP_KSWAPD_RECLAIM to identify callers that want to wake kswapd for background reclaim. __GFP_WAIT is redefined as a caller that is willing to enter direct reclaim and wake kswapd for background reclaim. This patch then converts a number of sites o __GFP_ATOMIC is used by callers that are high priority and have memory pools for those requests. GFP_ATOMIC uses this flag. o Callers that have a limited mempool to guarantee forward progress clear __GFP_DIRECT_RECLAIM but keep __GFP_KSWAPD_RECLAIM. bio allocations fall into this category where kswapd will still be woken but atomic reserves are not used as there is a one-entry mempool to guarantee progress. o Callers that are checking if they are non-blocking should use the helper gfpflags_allow_blocking() where possible. This is because checking for __GFP_WAIT as was done historically now can trigger false positives. Some exceptions like dm-crypt.c exist where the code intent is clearer if __GFP_DIRECT_RECLAIM is used instead of the helper due to flag manipulations. o Callers that built their own GFP flags instead of starting with GFP_KERNEL and friends now also need to specify __GFP_KSWAPD_RECLAIM. The first key hazard to watch out for is callers that removed __GFP_WAIT and was depending on access to atomic reserves for inconspicuous reasons. In some cases it may be appropriate for them to use __GFP_HIGH. The second key hazard is callers that assembled their own combination of GFP flags instead of starting with something like GFP_KERNEL. They may now wish to specify __GFP_KSWAPD_RECLAIM. It's almost certainly harmless if it's missed in most cases as other activity will wake kswapd. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Vitaly Wool <vitalywool@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-04Merge branch 'for-4.4/core' of git://git.kernel.dk/linux-blockLinus Torvalds1-0/+4
Pull core block updates from Jens Axboe: "This is the core block pull request for 4.4. I've got a few more topic branches this time around, some of them will layer on top of the core+drivers changes and will come in a separate round. So not a huge chunk of changes in this round. This pull request contains: - Enable blk-mq page allocation tracking with kmemleak, from Catalin. - Unused prototype removal in blk-mq from Christoph. - Cleanup of the q->blk_trace exchange, using cmpxchg instead of two xchg()'s, from Davidlohr. - A plug flush fix from Jeff. - Also from Jeff, a fix that means we don't have to update shared tag sets at init time unless we do a state change. This cuts down boot times on thousands of devices a lot with scsi/blk-mq. - blk-mq waitqueue barrier fix from Kosuke. - Various fixes from Ming: - Fixes for segment merging and splitting, and checks, for the old core and blk-mq. - Potential blk-mq speedup by marking ctx pending at the end of a plug insertion batch in blk-mq. - direct-io no page dirty on kernel direct reads. - A WRITE_SYNC fix for mpage from Roman" * 'for-4.4/core' of git://git.kernel.dk/linux-block: blk-mq: avoid excessive boot delays with large lun counts blktrace: re-write setting q->blk_trace blk-mq: mark ctx as pending at batch in flush plug path blk-mq: fix for trace_block_plug() block: check bio_mergeable() early before merging blk-mq: check bio_mergeable() early before merging block: avoid to merge splitted bio block: setup bi_phys_segments after splitting block: fix plug list flushing for nomerge queues blk-mq: remove unused blk_mq_clone_flush_request prototype blk-mq: fix waitqueue_active without memory barrier in block/blk-mq-tag.c fs: direct-io: don't dirtying pages for ITER_BVEC/ITER_KVEC direct read fs/mpage.c: forgotten WRITE_SYNC in case of data integrity write block: kmemleak: Track the page allocations for struct request
2015-10-15blk-mq: fix use-after-free in blk_mq_free_tag_set()Junichi Nomura1-0/+1
tags is freed in blk_mq_free_rq_map() and should not be used after that. The problem doesn't manifest if CONFIG_CPUMASK_OFFSTACK is false because free_cpumask_var() is nop. tags->cpumask is allocated in blk_mq_init_tags() so it's natural to free cpumask in its counter part, blk_mq_free_tags(). Fixes: f26cdc8536ad ("blk-mq: Shared tag enhancements") Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Cc: Keith Busch <keith.busch@intel.com> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-10-09blk-mq: fix waitqueue_active without memory barrier in block/blk-mq-tag.cKosuke Tatsukawa1-0/+4
blk_mq_tag_update_depth() seems to be missing a memory barrier which might cause the waker to not notice the waiter and fail to send a wake_up as in the following figure. blk_mq_tag_update_depth bt_get ------------------------------------------------------------------------ if (waitqueue_active(&bs->wait)) /* The CPU might reorder the test for the waitqueue up here, before prior writes complete */ prepare_to_wait(&bs->wait, &wait, TASK_UNINTERRUPTIBLE); tag = __bt_get(hctx, bt, last_tag, tags); /* Value set in bt_update_count not visible yet */ bt_update_count(&tags->bitmap_tags, tdepth); /* blk_mq_tag_wakeup_all(tags, false); */ bt = &tags->bitmap_tags; wake_index = atomic_read(&bt->wake_index); ... io_schedule(); ------------------------------------------------------------------------ This patch adds the missing memory barrier. I found this issue when I was looking through the linux source code for places calling waitqueue_active() before wake_up*(), but without preceding memory barriers, after sending a patch to fix a similar issue in drivers/tty/n_tty.c (Details about the original issue can be found here: https://lkml.org/lkml/2015/9/28/849). Signed-off-by: Kosuke Tatsukawa <tatsu@ab.jp.nec.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-10-01blk-mq: factor out a helper to iterate all tags for a request_queueChristoph Hellwig1-7/+20
And replace the blk_mq_tag_busy_iter with it - the driver use has been replaced with a new helper a while ago, and internal to the block we only need the new version. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-08-15blk-mq: fix race between timeout and freeing requestMing Lei1-2/+2
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>
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