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2020-07-02Merge tag 'block-5.8-2020-07-01' of git://git.kernel.dk/linux-blockLinus Torvalds
Pull block fixes from Jens Axboe: - Use kvfree_sensitive() for the block keyslot free (Eric) - Sync blk-mq debugfs flags (Hou) - Memory leak fix in virtio-blk error path (Hou) * tag 'block-5.8-2020-07-01' of git://git.kernel.dk/linux-block: virtio-blk: free vblk-vqs in error path of virtblk_probe() block/keyslot-manager: use kvfree_sensitive() blk-mq-debugfs: update blk_queue_flag_name[] accordingly for new flags
2020-07-02block: initialize current->bio_list[1] in __submit_bio_noacct_mqChristoph Hellwig
bio_alloc_bioset references current->bio_list[1], so we need to initialize it for the blk-mq submission path as well. Fixes: ff93ea0ce763 ("block: shortcut __submit_bio_noacct for blk-mq drivers") Reported-by: Qian Cai <cai@lca.pw> Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-07-02block: make function __bio_integrity_free() staticWei Yongjun
Fix sparse build warning: block/bio-integrity.c:27:6: warning: symbol '__bio_integrity_free' was not declared. Should it be static? Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-07-01Revert "blk-mq: put driver tag when this request is completed"Jens Axboe
This reverts commits the following commits: 37f4a24c2469a10a4c16c641671bd766e276cf9f 723bf178f158abd1ce6069cb049581b3cb003aab 36a3df5a4574d5ddf59804fcd0c4e9654c514d9a The last one is the culprit, but we have to go a bit deeper to get this to revert cleanly. There's been a report that this breaks some MMC setups [1], and also causes an issue with swap [2]. Until this can be figured out, revert the offending commits. [1] https://lore.kernel.org/linux-block/57fb09b1-54ba-f3aa-f82c-d709b0e6b281@samsung.com/ [2] https://lore.kernel.org/linux-block/20200702043721.GA1087@lca.pw/ Reported-by: Marek Szyprowski <m.szyprowski@samsung.com> Reported-by: Qian Cai <cai@lca.pw> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-07-01blk-iolatency: only call ktime_get() if neededHongnan Li
ktime_to_ns(ktime_get()), which is expensive, does not need to be called if blk_iolatency_enabled() return false in blkcg_iolatency_done_bio(). Postponing ktime_to_ns(ktime_get()) execution reduces the CPU usage when blk_iolatency is disabled. Signed-off-by: Hongnan Li <hongnan.li@linux.alibaba.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-07-01block: remove direct_make_requestChristoph Hellwig
Now that submit_bio_noacct has a decent blk-mq fast path there is no more need for this bypass. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-07-01block: shortcut __submit_bio_noacct for blk-mq driversChristoph Hellwig
For blk-mq drivers bios can only be inserted for the same queue. So bypass the complicated sorting logic in __submit_bio_noacct with a blk-mq simpler submission helper. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-07-01block: refator submit_bio_noacctChristoph Hellwig
Split out a __submit_bio_noacct helper for the actual de-recursion algorithm, and simplify the loop by using a continue when we can't enter the queue for a bio. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-07-01block: rename generic_make_request to submit_bio_noacctChristoph Hellwig
generic_make_request has always been very confusingly misnamed, so rename it to submit_bio_noacct to make it clear that it is submit_bio minus accounting and a few checks. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-07-01block: move ->make_request_fn to struct block_device_operationsChristoph Hellwig
The make_request_fn is a little weird in that it sits directly in struct request_queue instead of an operation vector. Replace it with a block_device_operations method called submit_bio (which describes much better what it does). Also remove the request_queue argument to it, as the queue can be derived pretty trivially from the bio. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-07-01block: remove the nr_sectors variable in generic_make_request_checksChristoph Hellwig
The variable is only used once, so just open code the bio_sector() there. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-07-01block: remove the NULL queue check in generic_make_request_checksChristoph Hellwig
All registers disks must have a valid queue pointer, so don't bother to log a warning for that case. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-07-01block: tidy up a warning in bio_check_roChristoph Hellwig
The "generic_make_request: " prefix has no value, and will soon become stale. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-07-01block: remove the request_queue argument from blk_queue_splitChristoph Hellwig
The queue can be trivially derived from the bio, so pass one less argument. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-07-01blk-mq: remove pointless call of list_entry_rq() in hctx_show_busy_rq()Hou Tao
Just use rq directly, the usage of list_entry_rq() doesn't make any sense. Signed-off-by: Hou Tao <houtao1@huawei.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-30blk-cgroup: clean up indentationColin Ian King
There is a statement that is indented one level too deeply, fix it by removing a tab. Signed-off-by: Colin Ian King <colin.king@canonical.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-30blk-mq: centralise related handling into blk_mq_get_driver_tagMing Lei
Move .nr_active update and request assignment into blk_mq_get_driver_tag(), all are good to do during getting driver tag. Meantime blk-flush related code is simplified and flush request needn't to update the request table manually any more. Signed-off-by: Ming Lei <ming.lei@redhat.com> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-30blk-mq: move blk_mq_put_driver_tag() into blk-mq.cMing Lei
It is used by blk-mq.c only, so move it to the source file. Suggested-by: Christoph Hellwig <hch@infradead.org> Signed-off-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-30blk-mq: move blk_mq_get_driver_tag into blk-mq.cMing Lei
blk_mq_get_driver_tag() is only used by blk-mq.c and is supposed to stay in blk-mq.c, so move it and preparing for cleanup code of get/put driver tag. Meantime hctx_may_queue() is moved to header file and it is fine since it is defined as inline always. No functional change. Signed-off-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-30blk-mq: support batching dispatch in case of ioMing Lei
More and more drivers want to get batching requests queued from block layer, such as mmc, and tcp based storage drivers. Also current in-tree users have virtio-scsi, virtio-blk and nvme. For none, we already support batching dispatch. But for io scheduler, every time we just take one request from scheduler and pass the single request to blk_mq_dispatch_rq_list(). This way makes batching dispatch not possible when io scheduler is applied. One reason is that we don't want to hurt sequential IO performance, becasue IO merge chance is reduced if more requests are dequeued from scheduler queue. Try to support batching dispatch for io scheduler by starting with the following simple approach: 1) still make sure we can get budget before dequeueing request 2) use hctx->dispatch_busy to evaluate if queue is busy, if it is busy we fackback to non-batching dispatch, otherwise dequeue as many as possible requests from scheduler, and pass them to blk_mq_dispatch_rq_list(). Wrt. 2), we use similar policy for none, and turns out that SCSI SSD performance got improved much. In future, maybe we can develop more intelligent algorithem for batching dispatch. Baolin has tested this patch and found that MMC performance is improved[3]. [1] https://lore.kernel.org/linux-block/20200512075501.GF1531898@T590/#r [2] https://lore.kernel.org/linux-block/fe6bd8b9-6ed9-b225-f80c-314746133722@grimberg.me/ [3] https://lore.kernel.org/linux-block/CADBw62o9eTQDJ9RvNgEqSpXmg6Xcq=2TxH0Hfxhp29uF2W=TXA@mail.gmail.com/ Signed-off-by: Ming Lei <ming.lei@redhat.com> Tested-by: Baolin Wang <baolin.wang7@gmail.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Cc: Sagi Grimberg <sagi@grimberg.me> Cc: Baolin Wang <baolin.wang7@gmail.com> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-30blk-mq: pass obtained budget count to blk_mq_dispatch_rq_listMing Lei
Pass obtained budget count to blk_mq_dispatch_rq_list(), and prepare for supporting fully batching submission. With the obtained budget count, it is easier to put extra budgets in case of .queue_rq failure. Meantime remove the old 'got_budget' parameter. Signed-off-by: Ming Lei <ming.lei@redhat.com> Tested-by: Baolin Wang <baolin.wang7@gmail.com> Reviewed-by: Christoph Hellwig <hch@infradead.org> Cc: Sagi Grimberg <sagi@grimberg.me> Cc: Baolin Wang <baolin.wang7@gmail.com> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-30blk-mq: remove dead check from blk_mq_dispatch_rq_listMing Lei
When BLK_STS_RESOURCE or BLK_STS_DEV_RESOURCE is returned from .queue_rq, the 'list' variable always holds this rq which isn't queued to LLD successfully. So blk_mq_dispatch_rq_list() always returns false from the branch of '!list_empty(list)'. No functional change. Signed-off-by: Ming Lei <ming.lei@redhat.com> Tested-by: Baolin Wang <baolin.wang7@gmail.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Reviewed-by: Christoph Hellwig <hch@infradead.org> Cc: Sagi Grimberg <sagi@grimberg.me> Cc: Baolin Wang <baolin.wang7@gmail.com> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-30blk-mq: move getting driver tag and budget into one helperMing Lei
Move code for getting driver tag and budget into one helper, so blk_mq_dispatch_rq_list gets a bit simplified, and easier to read. Meantime move updating of 'no_tag' and 'no_budget_available' into the branch for handling partial dispatch because that is exactly consumer of the two local variables. Also rename the parameter of 'got_budget' as 'ask_budget'. No functional change. Signed-off-by: Ming Lei <ming.lei@redhat.com> Tested-by: Baolin Wang <baolin.wang7@gmail.com> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Reviewed-by: Christoph Hellwig <hch@infradead.org> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Cc: Sagi Grimberg <sagi@grimberg.me> Cc: Baolin Wang <baolin.wang7@gmail.com> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-30blk-mq: pass hctx to blk_mq_dispatch_rq_listMing Lei
All requests in the 'list' of blk_mq_dispatch_rq_list belong to same hctx, so it is better to pass hctx instead of request queue, because blk-mq's dispatch target is hctx instead of request queue. Signed-off-by: Ming Lei <ming.lei@redhat.com> Tested-by: Baolin Wang <baolin.wang7@gmail.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Cc: Sagi Grimberg <sagi@grimberg.me> Cc: Baolin Wang <baolin.wang7@gmail.com> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-30blk-mq: pass request queue into get/put budget callbackMing Lei
blk-mq budget is abstract from scsi's device queue depth, and it is always per-request-queue instead of hctx. It can be quite absurd to get a budget from one hctx, then dequeue a request from scheduler queue, and this request may not belong to this hctx, at least for bfq and deadline. So fix the mess and always pass request queue to get/put budget callback. Signed-off-by: Ming Lei <ming.lei@redhat.com> Tested-by: Baolin Wang <baolin.wang7@gmail.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Douglas Anderson <dianders@chromium.org> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Cc: Sagi Grimberg <sagi@grimberg.me> Cc: Baolin Wang <baolin.wang7@gmail.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Douglas Anderson <dianders@chromium.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-29block/keyslot-manager: use kvfree_sensitive()Eric Biggers
Make blk_ksm_destroy() use the kvfree_sensitive() function (which was introduced in v5.8-rc1) instead of open-coding it. Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-29blk-mq: remove the BLK_MQ_REQ_INTERNAL flagChristoph Hellwig
Just check for a non-NULL elevator directly to make the code more clear. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-29blk-mq: put driver tag when this request is completedMing Lei
It is natural to release driver tag when this request is completed by LLD or device since its purpose is for LLD use. One big benefit is that the released tag can be re-used quicker since bio_endio() may take too long. Meantime we don't need to release driver tag for flush request. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-29blk-cgroup: remove a dead check in blk_throtl_bioChristoph Hellwig
bios must have a valid block group by the time they are submitted. Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-29blk-cgroup: remove blkcg_bio_issue_checkChristoph Hellwig
blkcg_bio_issue_check is a giant inline function that does three entirely different things. Factor out the blk-cgroup related bio initalization into a new helper, and the open code the sequence in the only caller, relying on the fact that all the actual functionality is stubbed out for non-cgroup builds. Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-29blk-cgroup: move rcu locking from blkcg_bio_issue_check to blk_throtl_bioChristoph Hellwig
The only thing in blkcg_bio_issue_check that needs to be under rcu_read_lock is blk_throtl_bio, so move the locking there. Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-29block: move the initial blkg lookup into blkg_tryget_closestChristoph Hellwig
By moving the initial blkg lookup into blkg_tryget_closest we get a nicely self contained routines that does all the RCU locking. Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-29block: bypass blkg_tryget_closest for the root_blkgChristoph Hellwig
The root_blkg is only torn down at the very end of removing a queue. So in the I/O submission path is always has a life reference and we can just grab another one using blkg_get instead of doing a tryget and parent walk that won't lead anywhere. Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-29block: merge blkg_lookup_create and __blkg_lookup_createChristoph Hellwig
No good reason to keep these two functions split. Acked-by: Tejun Heo <tj@kernel.org> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-29block: move the bio cgroup associatation helpers to blk-cgroup.cChristoph Hellwig
Keep the cgroup code together. Acked-by: Tejun Heo <tj@kernel.org> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-29block: move bio_associate_blkg_from_page to mm/page_io.cChristoph Hellwig
bio_associate_blkg_from_page is a special purpose helper for swap bios that doesn't need access to bio internals. Move it to the swap code instead of having it in bio.c. Acked-by: Tejun Heo <tj@kernel.org> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-29block: merge __bio_associate_blkg into bio_associate_blkg_from_cssChristoph Hellwig
Merge __bio_associate_blkg into the only caller, which allows to slightly reduce the RCU crticial section and better explain the code flow. Acked-by: Tejun Heo <tj@kernel.org> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-29block: really clone the block cgroup in bio_clone_blkg_associationChristoph Hellwig
bio_clone_blkg_association is supposed to clone the associatation, but actually ends up doing a search with a tryget. As we know we have a reference on the source cgroup just get an unconditional additional reference to it and call it a day. That also removes the need for a RCU critical section. Acked-by: Tejun Heo <tj@kernel.org> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-29block: remove bio_disassociate_blkgChristoph Hellwig
bio_disassociate_blkg has two callers, of which one immediately assigns a new value to >bi_blkg. Just open code the function in the two callers. Acked-by: Tejun Heo <tj@kernel.org> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-29blk-mq-debugfs: update blk_queue_flag_name[] accordingly for new flagsHou Tao
Else there may be magic numbers in /sys/kernel/debug/block/*/state. Signed-off-by: Hou Tao <houtao1@huawei.com> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-28blk-rq-qos: remove redundant finish_wait to rq_qos_wait.Guo Xuenan
It is no need do finish_wait twice after acquiring inflight. Signed-off-by: Guo Xuenan <guoxuenan@huawei.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-27Merge tag 'block-5.8-2020-06-26' of git://git.kernel.dk/linux-blockLinus Torvalds
Pull block fixes from Jens Axboe: - NVMe pull request from Christoph: - multipath deadlock fixes (Anton) - NUMA fixes (Max) - RDMA completion vector fix (Max) - IO deadlock fix (Sagi) - multipath reference fix (Sagi) - NS mutation fix (Sagi) - Use right allocator when freeing bip in error path (Chengguang) * tag 'block-5.8-2020-06-26' of git://git.kernel.dk/linux-block: nvme-multipath: fix bogus request queue reference put nvme-multipath: fix deadlock due to head->lock nvme: don't protect ns mutation with ns->head->lock nvme-multipath: fix deadlock between ana_work and scan_work nvme: fix possible deadlock when I/O is blocked nvme-rdma: assign completion vector correctly nvme-loop: initialize tagset numa value to the value of the ctrl nvme-tcp: initialize tagset numa value to the value of the ctrl nvme-pci: initialize tagset numa value to the value of the ctrl nvme-pci: override the value of the controller's numa node nvme: set initial value for controller's numa node block: release bip in a right way in error path
2020-06-25blktrace: Provide event for request mergingJan Kara
Currently blk-mq does not report any event when two requests get merged in the elevator. This then results in difficult to understand sequence of events like: ... 8,0 34 1579 0.608765271 2718 I WS 215023504 + 40 [dbench] 8,0 34 1584 0.609184613 2719 A WS 215023544 + 56 <- (8,4) 2160568 8,0 34 1585 0.609184850 2719 Q WS 215023544 + 56 [dbench] 8,0 34 1586 0.609188524 2719 G WS 215023544 + 56 [dbench] 8,0 3 602 0.609684162 773 D WS 215023504 + 96 [kworker/3:1H] 8,0 34 1591 0.609843593 0 C WS 215023504 + 96 [0] and you can only guess (after quite some headscratching since the above excerpt is intermixed with a lot of other IO) that request 215023544+56 got merged to request 215023504+40. Provide proper event for request merging like we used to do in the legacy block layer. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-24blk-iocost: Use struct_size() in kzalloc_node()Gustavo A. R. Silva
Make use of the struct_size() helper instead of an open-coded version in order to avoid any potential type mistakes. This code was detected with the help of Coccinelle and, audited and fixed manually. Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> Addresses-KSPP-ID: https://github.com/KSPP/linux/issues/83 Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-24block: bio: Use struct_size() in kmalloc()Gustavo A. R. Silva
Make use of the struct_size() helper instead of an open-coded version in order to avoid any potential type mistakes. This code was detected with the help of Coccinelle and, audited and fixed manually. Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> Addresses-KSPP-ID: https://github.com/KSPP/linux/issues/83 Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-24block: create the request_queue debugfs_dir on registrationLuis Chamberlain
We were only creating the request_queue debugfs_dir only for make_request block drivers (multiqueue), but never for request-based block drivers. We did this as we were only creating non-blktrace additional debugfs files on that directory for make_request drivers. However, since blktrace *always* creates that directory anyway, we special-case the use of that directory on blktrace. Other than this being an eye-sore, this exposes request-based block drivers to the same debugfs fragile race that used to exist with make_request block drivers where if we start adding files onto that directory we can later run a race with a double removal of dentries on the directory if we don't deal with this carefully on blktrace. Instead, just simplify things by always creating the request_queue debugfs_dir on request_queue registration. Rename the mutex also to reflect the fact that this is used outside of the blktrace context. Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-24block: revert back to synchronous request_queue removalLuis Chamberlain
Commit dc9edc44de6c ("block: Fix a blk_exit_rl() regression") merged on v4.12 moved the work behind blk_release_queue() into a workqueue after a splat floated around which indicated some work on blk_release_queue() could sleep in blk_exit_rl(). This splat would be possible when a driver called blk_put_queue() or blk_cleanup_queue() (which calls blk_put_queue() as its final call) from an atomic context. blk_put_queue() decrements the refcount for the request_queue kobject, and upon reaching 0 blk_release_queue() is called. Although blk_exit_rl() is now removed through commit db6d99523560 ("block: remove request_list code") on v5.0, we reserve the right to be able to sleep within blk_release_queue() context. The last reference for the request_queue must not be called from atomic context. *When* the last reference to the request_queue reaches 0 varies, and so let's take the opportunity to document when that is expected to happen and also document the context of the related calls as best as possible so we can avoid future issues, and with the hopes that the synchronous request_queue removal sticks. We revert back to synchronous request_queue removal because asynchronous removal creates a regression with expected userspace interaction with several drivers. An example is when removing the loopback driver, one uses ioctls from userspace to do so, but upon return and if successful, one expects the device to be removed. Likewise if one races to add another device the new one may not be added as it is still being removed. This was expected behavior before and it now fails as the device is still present and busy still. Moving to asynchronous request_queue removal could have broken many scripts which relied on the removal to have been completed if there was no error. Document this expectation as well so that this doesn't regress userspace again. Using asynchronous request_queue removal however has helped us find other bugs. In the future we can test what could break with this arrangement by enabling CONFIG_DEBUG_KOBJECT_RELEASE. While at it, update the docs with the context expectations for the request_queue / gendisk refcount decrement, and make these expectations explicit by using might_sleep(). Fixes: dc9edc44de6c ("block: Fix a blk_exit_rl() regression") Suggested-by: Nicolai Stange <nstange@suse.de> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Cc: Bart Van Assche <bvanassche@acm.org> Cc: Omar Sandoval <osandov@fb.com> Cc: Hannes Reinecke <hare@suse.com> Cc: Nicolai Stange <nstange@suse.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: yu kuai <yukuai3@huawei.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-24block: clarify context for refcount increment helpersLuis Chamberlain
Let us clarify the context under which the helpers to increment the refcount for the gendisk and request_queue can be called under. We make this explicit on the places where we may sleep with might_sleep(). We don't address the decrement context yet, as that needs some extra work and fixes, but will be addressed in the next patch. Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-24block: add docs for gendisk / request_queue refcount helpersLuis Chamberlain
This adds documentation for the gendisk / request_queue refcount helpers. Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-24blk-mq: add a new blk_mq_complete_request_remote APIChristoph Hellwig
This is a variant of blk_mq_complete_request_remote that only completes the request if it needs to be bounced to another CPU or a softirq. If the request can be completed locally the function returns false and lets the driver complete it without requring and indirect function call. Reviewed-by: Daniel Wagner <dwagner@suse.de> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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