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2024-11-07block: don't verify IO lock for freeze/unfreeze in elevator_init_mq()Ming Lei1-2/+8
elevator_init_mq() is only called at the entry of add_disk_fwnode() when disk IO isn't allowed yet. So not verify io lock(q->io_lockdep_map) for freeze & unfreeze in elevator_init_mq(). Reported-by: Marek Szyprowski <m.szyprowski@samsung.com> Reported-by: Lai Yi <yi1.lai@linux.intel.com> Fixes: f1be1788a32e ("block: model freeze & enter queue as lock for supporting lockdep") Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20241031133723.303835-5-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-10-22block: return void from the queue_sysfs_entry load_module methodChristoph Hellwig1-5/+3
Requesting a module either succeeds or does nothing, return an error from this method does not make sense. Also move the load_module after the store method in the struct declaration to keep the important show and store methods together. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org> Link: https://lore.kernel.org/r/20241008050841.104602-1-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-10-11elevator: Remove argument from elevator_find_getBreno Leitao1-4/+3
Commit e4eb37cc0f3ed ("block: Remove elevator required features") removed the usage of `struct request_queue` from elevator_find_get(), but didn't removed the argument. Remove the "struct request_queue *q" argument from elevator_find_get() given it is useless. Fixes: e4eb37cc0f3e ("block: Remove elevator required features") Signed-off-by: Breno Leitao <leitao@debian.org> Link: https://lore.kernel.org/r/20241011155615.3361143-1-leitao@debian.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-10-11elevator: do not request_module if elevator existsBreno Leitao1-1/+9
Whenever an I/O elevator is changed, the system attempts to load a module for the new elevator. This occurs regardless of whether the elevator is already loaded or built directly into the kernel. This behavior introduces unnecessary overhead and potential issues. This makes the operation slower, and more error-prone. For instance, making the problem fixed by [1] visible for users that doesn't even rely on modules being available through modules. Do not try to load the ioscheduler if it is already visible. This change brings two main benefits: it improves the performance of elevator changes, and it reduces the likelihood of errors occurring during this process. [1] Commit e3accac1a976 ("block: Fix elv_iosched_local_module handling of "none" scheduler") Fixes: 734e1a860312 ("block: Prevent deadlocks when switching elevators") Signed-off-by: Breno Leitao <leitao@debian.org> Link: https://lore.kernel.org/r/20241011170122.3880087-1-leitao@debian.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-10-07block: Fix elevator_get_default() checking for NULL q->tag_setSurajSonawane24151-2/+2
elevator_get_default() and elv_support_iosched() both check for whether or not q->tag_set is non-NULL, however it's not possible for them to be NULL. This messes up some static checkers, as the checking of tag_set isn't consistent. Remove the checks, which both simplifies the logic and avoids checker errors. Signed-off-by: SurajSonawane2415 <surajsonawane0215@gmail.com> Link: https://lore.kernel.org/r/20241007111416.13814-1-surajsonawane0215@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-09-17block: Fix elv_iosched_local_module handling of "none" schedulerDamien Le Moal1-1/+3
Commit 734e1a860312 ("block: Prevent deadlocks when switching elevators") introduced the function elv_iosched_load_module() to allow loading an elevator module outside of elv_iosched_store() with the target device queue not frozen, to avoid deadlocks. However, the "none" scheduler does not have a module and as a result, elv_iosched_load_module() always returns an error when trying to switch to this valid scheduler. Fix this by ignoring the return value of the request_module() call done by elv_iosched_load_module(). This restores the behavior before commit 734e1a860312, which was to ignore the request_module() result and instead rely on elevator_change() to handle the "none" scheduler case. Reported-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com> Fixes: 734e1a860312 ("block: Prevent deadlocks when switching elevators") Cc: stable@vger.kernel.org Signed-off-by: Damien Le Moal <dlemoal@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20240917133231.134806-1-dlemoal@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-09-10block: Prevent deadlocks when switching elevatorsDamien Le Moal1-6/+15
Commit af2814149883 ("block: freeze the queue in queue_attr_store") changed queue_attr_store() to always freeze a sysfs attribute queue before calling the attribute store() method, to ensure that no IOs are in-flight when an attribute value is being updated. However, this change created a potential deadlock situation for the scheduler queue attribute as changing the queue elevator with elv_iosched_store() can result in a call to request_module() if the user requested module is not already registered. If the file of the requested module is stored on the block device of the frozen queue, a deadlock will happen as the read operations triggered by request_module() will wait for the queue freeze to end. Solve this issue by introducing the load_module method in struct queue_sysfs_entry, and to calling this method function in queue_attr_store() before freezing the attribute queue. The macro definition QUEUE_RW_LOAD_MODULE_ENTRY() is added to define a queue sysfs attribute that needs loading a module. The definition of the scheduler atrribute is changed to using QUEUE_RW_LOAD_MODULE_ENTRY(), with the function elv_iosched_load_module() defined as the load_module method. elv_iosched_store() can then be simplified to remove the call to request_module(). Reported-by: Richard W.M. Jones <rjones@redhat.com> Reported-by: Jiri Jaburek <jjaburek@redhat.com> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219166 Fixes: af2814149883 ("block: freeze the queue in queue_attr_store") Cc: stable@vger.kernel.org Signed-off-by: Damien Le Moal <dlemoal@kernel.org> Tested-by: Richard W.M. Jones <rjones@redhat.com> Link: https://lore.kernel.org/r/20240908000704.414538-1-dlemoal@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-06-28block: pass a gendisk to the queue_sysfs_entry methodsChristoph Hellwig1-4/+5
The kobject for the queue entries is embedded into a struct gendisk. Pass it to the sysfs methods instead of the request_queue derived from it. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20240627111407.476276-4-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-04-17block: Remove elevator required featuresDamien Le Moal1-41/+5
The only elevator feature ever implemented is ELEVATOR_F_ZBD_SEQ_WRITE for signaling that a scheduler implements zone write locking to tightly control the dispatching order of write operations to zoned block devices. With the removal of zone write locking support in mq-deadline and the reliance of all block device drivers on the block layer zone write plugging to control ordering of write operations to zones, the elevator feature ELEVATOR_F_ZBD_SEQ_WRITE is completely unused. Remove it, and also remove the now unused code for filtering the possible schedulers for a block device based on required features. Signed-off-by: Damien Le Moal <dlemoal@kernel.org> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Hans Holmberg <hans.holmberg@wdc.com> Tested-by: Dennis Maisenbacher <dennis.maisenbacher@wdc.com> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Link: https://lore.kernel.org/r/20240408014128.205141-23-dlemoal@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-08-19blk-mq: release scheduler resource when request completesChengming Zhou1-0/+3
Chuck reported [1] an IO hang problem on NFS exports that reside on SATA devices and bisected to commit 615939a2ae73 ("blk-mq: defer to the normal submission path for post-flush requests"). We analysed the IO hang problem, found there are two postflush requests waiting for each other. The first postflush request completed the REQ_FSEQ_DATA sequence, so go to the REQ_FSEQ_POSTFLUSH sequence and added in the flush pending list, but failed to blk_kick_flush() because of the second postflush request which is inflight waiting in scheduler queue. The second postflush waiting in scheduler queue can't be dispatched because the first postflush hasn't released scheduler resource even though it has completed by itself. Fix it by releasing scheduler resource when the first postflush request completed, so the second postflush can be dispatched and completed, then make blk_kick_flush() succeed. While at it, remove the check for e->ops.finish_request, as all schedulers set that. Reaffirm this requirement by adding a WARN_ON_ONCE() at scheduler registration time, just like we do for insert_requests and dispatch_request. [1] https://lore.kernel.org/all/7A57C7AE-A51A-4254-888B-FE15CA21F9E9@oracle.com/ Link: https://lore.kernel.org/linux-block/20230819031206.2744005-1-chengming.zhou@linux.dev/ Reported-by: kernel test robot <oliver.sang@intel.com> Closes: https://lore.kernel.org/oe-lkp/202308172100.8ce4b853-oliver.sang@intel.com Fixes: 615939a2ae73 ("blk-mq: defer to the normal submission path for post-flush requests") Reported-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com> Tested-by: Chuck Lever <chuck.lever@oracle.com> Link: https://lore.kernel.org/r/20230813152325.3017343-1-chengming.zhou@linux.dev [axboe: folded in incremental fix and added tags] Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-06-01block: Replace all non-returning strlcpy with strscpyAzeem Shaikh1-1/+1
strlcpy() reads the entire source buffer first. This read may exceed the destination size limit. This is both inefficient and can lead to linear read overflows if a source string is not NUL-terminated [1]. In an effort to remove strlcpy() completely [2], replace strlcpy() here with strscpy(). No return values were used, so direct replacement is safe. [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy [2] https://github.com/KSPP/linux/issues/89 Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com> Reviewed-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20230530155608.272266-1-azeemshaikh38@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-02-09block: make kobj_type structures constantThomas Weißschuh1-2/+2
Since commit ee6d3dd4ed48 ("driver core: make kobj_type constant.") the driver core allows the usage of const struct kobj_type. Take advantage of this to constify the structure definitions to prevent modification at runtime. Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> Link: https://lore.kernel.org/r/20230208-kobj_type-block-v1-1-0b3eafd7d983@weissschuh.net Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-30block: untangle request_queue refcounting from sysfsChristoph Hellwig1-1/+1
The kobject embedded into the request_queue is used for the queue directory in sysfs, but that is a child of the gendisks directory and is intimately tied to it. Move this kobject to the gendisk and use a refcount_t in the request_queue for the actual request_queue refcounting that is completely unrelated to the device model. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20221114042637.1009333-5-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-29block: use bool as the return type of elv_iosched_allow_bio_mergeJinlong Chen1-2/+2
We have bool type now, update the old signature. Signed-off-by: Jinlong Chen <nickyc975@zju.edu.cn> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/0db0a0298758d60d0f4df8b7126ac6a381e5a5bb.1669736350.git.nickyc975@zju.edu.cn Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-29block: replace "len+name" with "name+len" in elv_iosched_showJinlong Chen1-1/+1
The "pointer + offset" pattern is more resonable. Signed-off-by: Jinlong Chen <nickyc975@zju.edu.cn> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/d9beaee71b14f7b2a39ab0db6458dc0f7d961ceb.1669736350.git.nickyc975@zju.edu.cn Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-29block: always use 'e' when printing scheduler nameJinlong Chen1-1/+1
Printing e->elevator_name in all cases improves the readability, and 'e' and 'cur' are identical in this branch. Suggested-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jinlong Chen <nickyc975@zju.edu.cn> Link: https://lore.kernel.org/r/4bae180ffbac608ea0cf46ffa9739ce0973b60aa.1669736350.git.nickyc975@zju.edu.cn Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-29block: replace continue with else-if in elv_iosched_showJinlong Chen1-4/+2
else-if is more readable than continue here. Signed-off-by: Jinlong Chen <nickyc975@zju.edu.cn> Link: https://lore.kernel.org/r/77ac19ba556efd2c8639a6396eb4203c59bc13d6.1669736350.git.nickyc975@zju.edu.cn Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-29block: include 'none' for initial elv_iosched_show callJinlong Chen1-5/+4
This makes the printing order of the io schedulers consistent, and removes a redundant q->elevator check. Signed-off-by: Jinlong Chen <nickyc975@zju.edu.cn> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/bdd7083ed4f232e3285f39081e3c5f30b20b8da2.1669736350.git.nickyc975@zju.edu.cn Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-23elevator: remove an outdated comment in elevator_changeJinlong Chen1-3/+0
mq is no longer a special case. Signed-off-by: Jinlong Chen <nickyc975@zju.edu.cn> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/cbf47824fc726440371e74c867bf635ae1b671a3.1669126766.git.nickyc975@zju.edu.cn Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-23elevator: update the document of elevator_matchJinlong Chen1-3/+2
elevator_match does not care about elevator_features any more. Remove related descriptions from its document. Fixes: ffb86425ee2c ("block: don't check for required features in elevator_match") Signed-off-by: Jinlong Chen <nickyc975@zju.edu.cn> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/a58424555202c07a9ccf7f60c3ad7e247da09e25.1669126766.git.nickyc975@zju.edu.cn Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-23elevator: printk a warning if switching to a new io scheduler failsJinlong Chen1-0/+6
printk a warning to indicate that the io scheduler has been set to none if switching to a new io scheduler fails. Suggested-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jinlong Chen <nickyc975@zju.edu.cn> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/d51ed0fb457db7a4f9cbb0dbce36d534e22be457.1669126766.git.nickyc975@zju.edu.cn Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-23elevator: update the document of elevator_switchJinlong Chen1-4/+4
We no longer support falling back to the old io scheduler if switching to the new one fails. Update the document to indicate that. Fixes: a1ce35fa4985 ("block: remove dead elevator code") Signed-off-by: Jinlong Chen <nickyc975@zju.edu.cn> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/94250961689ba7d2e67a7d9e7995a11166fedb31.1669126766.git.nickyc975@zju.edu.cn Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-07block: Fix some kernel-doc commentsYang Li1-1/+0
Remove the description of @required_features in elevator_match() to clear the below warning: block/elevator.c:103: warning: Excess function parameter 'required_features' description in 'elevator_match' Link: https://bugzilla.openanolis.cn/show_bug.cgi?id=2734 Fixes: ffb86425ee2c ("block: don't check for required features in elevator_match") Reported-by: Abaci Robot <abaci@linux.alibaba.com> Signed-off-by: Yang Li <yang.lee@linux.alibaba.com> Link: https://lore.kernel.org/r/20221107062255.2685-1-yang.lee@linux.alibaba.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-01block: split elevator_switchChristoph Hellwig1-39/+38
Split an elevator_disable helper from elevator_switch for the case where we want to switch to no scheduler at all. This includes removing the pointless elevator_switch_mq helper and removing the switch to no schedule logic from blk_mq_init_sched. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20221030100714.876891-8-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-01block: don't check for required features in elevator_matchChristoph Hellwig1-35/+16
Checking for the required features in the callers simplifies the code quite a bit, so do that. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20221030100714.876891-7-hch@lst.de [axboe: adjust for dropping patch 1, use __elevator_find()] Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-01block: simplify the check for the current elevator in elv_iosched_showChristoph Hellwig1-1/+1
Just compare the pointers instead of using the string based elevator_match. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20221030100714.876891-6-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-01block: cleanup the variable naming in elv_iosched_storeChristoph Hellwig1-9/+8
Use eq for the elevator_queue as done elsewhere. This frees e to be used for the loop iterator instead of the odd __ prefix. In addition rename elv to cur to make it more clear it is the currently selected elevator. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20221030100714.876891-5-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-01block: exit elv_iosched_show early when I/O schedulers are not supportedChristoph Hellwig1-3/+2
If the tag_set has BLK_MQ_F_NO_SCHED flag set we will never show any scheduler, so exit early. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20221030100714.876891-4-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-01block: cleanup elevator_getChristoph Hellwig1-15/+10
Do the request_module and repeated lookup in the only caller that cares, pick a saner name that explains where are actually doing a lookup and use a sane calling conventions that passes the queue first. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20221030100714.876891-3-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-10-23block: fix up elevator_type refcountingJinlong Chen1-3/+7
The current reference management logic of io scheduler modules contains refcnt problems. For example, blk_mq_init_sched may fail before or after the calling of e->ops.init_sched. If it fails before the calling, it does nothing to the reference to the io scheduler module. But if it fails after the calling, it releases the reference by calling kobject_put(&eq->kobj). As the callers of blk_mq_init_sched can't know exactly where the failure happens, they can't handle the reference to the io scheduler module properly: releasing the reference on failure results in double-release if blk_mq_init_sched has released it, and not releasing the reference results in ghost reference if blk_mq_init_sched did not release it either. The same problem also exists in io schedulers' init_sched implementations. We can address the problem by adding releasing statements to the error handling procedures of blk_mq_init_sched and init_sched implementations. But that is counterintuitive and requires modifications to existing io schedulers. Instead, We make elevator_alloc get the io scheduler module references that will be released by elevator_release. And then, we match each elevator_get with an elevator_put. Therefore, each reference to an io scheduler module explicitly has its own getter and releaser, and we no longer need to worry about the refcnt problems. The bugs and the patch can be validated with tools here: https://github.com/nickyc975/linux_elv_refcnt_bug.git [hch: split out a few bits into separate patches, use a non-try module_get in elevator_alloc] Signed-off-by: Jinlong Chen <nickyc975@zju.edu.cn> Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20221020064819.1469928-5-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-10-23block: check for an unchanged elevator earlier in __elevator_changeJinlong Chen1-6/+3
No need to find the actual elevator_type struct for this comparism, the name is all that is needed. Signed-off-by: Jinlong Chen <nickyc975@zju.edu.cn> [hch: split from a larger patch] Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20221020064819.1469928-4-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-10-23block: sanitize the elevator name before passing it to __elevator_changeChristoph Hellwig1-8/+7
The stripped name should also be used for the none check. To do so strip it in the caller and pass in the sanitized name. Drop the pointless __ prefix in the function name while we're at it. Based on a patch from Jinlong Chen <nickyc975@zju.edu.cn>. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20221020064819.1469928-3-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-10-23block: add proper helpers for elevator_type module refcount managementChristoph Hellwig1-7/+2
Make sure we have helpers for all relevant module refcount operations on the elevator_type in elevator.h, and use them. Move the call to the get helper in blk_mq_elv_switch_none a bit so that it is obvious with a less verbose comment. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20221020064819.1469928-2-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-10-23elevator: add new field flags in struct elevator_queueYu Kuai1-4/+2
There are only one flag to indicate that elevator is registered currently, prepare to add a flag to disable wbt if default elevator is bfq. Signed-off-by: Yu Kuai <yukuai3@huawei.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20221019121518.3865235-6-yukuai1@huaweicloud.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-10-23elevator: remove redundant code in elv_unregister_queue()Yu Kuai1-2/+0
"elevator_queue *e" is already declared and initialized in the beginning of elv_unregister_queue(). Signed-off-by: Yu Kuai <yukuai3@huawei.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Eric Biggers <ebiggers@google.com> Link: https://lore.kernel.org/r/20221019121518.3865235-2-yukuai1@huaweicloud.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-09-27blk-mq: use quiesced elevator switch when reinitializing queuesKeith Busch1-2/+2
The hctx's run_work may be racing with the elevator switch when reinitializing hardware queues. The queue is merely frozen in this context, but that only prevents requests from allocating and doesn't stop the hctx work from running. The work may get an elevator pointer that's being torn down, and can result in use-after-free errors and kernel panics (example below). Use the quiesced elevator switch instead, and make the previous one static since it is now only used locally. nvme nvme0: resetting controller nvme nvme0: 32/0/0 default/read/poll queues BUG: kernel NULL pointer dereference, address: 0000000000000008 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 80000020c8861067 P4D 80000020c8861067 PUD 250f8c8067 PMD 0 Oops: 0000 [#1] SMP PTI Workqueue: kblockd blk_mq_run_work_fn RIP: 0010:kyber_has_work+0x29/0x70 ... Call Trace: __blk_mq_do_dispatch_sched+0x83/0x2b0 __blk_mq_sched_dispatch_requests+0x12e/0x170 blk_mq_sched_dispatch_requests+0x30/0x60 __blk_mq_run_hw_queue+0x2b/0x50 process_one_work+0x1ef/0x380 worker_thread+0x2d/0x3e0 Signed-off-by: Keith Busch <kbusch@kernel.org> Reviewed-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20220927155652.3260724-1-kbusch@fb.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-21Merge tag 'for-5.18/block-2022-03-18' of git://git.kernel.dk/linux-blockLinus Torvalds1-8/+8
Pull block updates from Jens Axboe: - BFQ cleanups and fixes (Yu, Zhang, Yahu, Paolo) - blk-rq-qos completion fix (Tejun) - blk-cgroup merge fix (Tejun) - Add offline error return value to distinguish it from an IO error on the device (Song) - IO stats fixes (Zhang, Christoph) - blkcg refcount fixes (Ming, Yu) - Fix for indefinite dispatch loop softlockup (Shin'ichiro) - blk-mq hardware queue management improvements (Ming) - sbitmap dead code removal (Ming, John) - Plugging merge improvements (me) - Show blk-crypto capabilities in sysfs (Eric) - Multiple delayed queue run improvement (David) - Block throttling fixes (Ming) - Start deprecating auto module loading based on dev_t (Christoph) - bio allocation improvements (Christoph, Chaitanya) - Get rid of bio_devname (Christoph) - bio clone improvements (Christoph) - Block plugging improvements (Christoph) - Get rid of genhd.h header (Christoph) - Ensure drivers use appropriate flush helpers (Christoph) - Refcounting improvements (Christoph) - Queue initialization and teardown improvements (Ming, Christoph) - Misc fixes/improvements (Barry, Chaitanya, Colin, Dan, Jiapeng, Lukas, Nian, Yang, Eric, Chengming) * tag 'for-5.18/block-2022-03-18' of git://git.kernel.dk/linux-block: (127 commits) block: cancel all throttled bios in del_gendisk() block: let blkcg_gq grab request queue's refcnt block: avoid use-after-free on throttle data block: limit request dispatch loop duration block/bfq-iosched: Fix spelling mistake "tenative" -> "tentative" sr: simplify the local variable initialization in sr_block_open() block: don't merge across cgroup boundaries if blkcg is enabled block: fix rq-qos breakage from skipping rq_qos_done_bio() block: flush plug based on hardware and software queue order block: ensure plug merging checks the correct queue at least once block: move rq_qos_exit() into disk_release() block: do more work in elevator_exit block: move blk_exit_queue into disk_release block: move q_usage_counter release into blk_queue_release block: don't remove hctx debugfs dir from blk_mq_exit_queue block: move blkcg initialization/destroy into disk allocation/release handler sr: implement ->free_disk to simplify refcounting sd: implement ->free_disk to simplify refcounting sd: delay calling free_opal_dev sd: call sd_zbc_release_disk before releasing the scsi_device reference ...
2022-03-08block: do more work in elevator_exitChristoph Hellwig1-3/+3
Move the calls to ioc_clear_queue and blk_mq_sched_free_rqs into elevator_exit. Except for one call where we know we can't have io_cq structures yet these always go together, and that extra call in an error path is harmless. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20220308055200.735835-14-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-02-28block: simplify calling convention of elv_unregister_queue()Eric Biggers1-4/+4
Make elv_unregister_queue() a no-op if q->elevator is NULL or is not registered. This simplifies the existing callers, as well as the future caller in the error path of blk_register_queue(). Also don't bother checking whether q is NULL, since it never is. Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Eric Biggers <ebiggers@google.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20220124215938.2769-2-ebiggers@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-02-17block/wbt: fix negative inflight counter when remove scsi deviceLaibin Qiu1-2/+0
Now that we disable wbt by set WBT_STATE_OFF_DEFAULT in wbt_disable_default() when switch elevator to bfq. And when we remove scsi device, wbt will be enabled by wbt_enable_default. If it become false positive between wbt_wait() and wbt_track() when submit write request. The following is the scenario that triggered the problem. T1 T2 T3 elevator_switch_mq bfq_init_queue wbt_disable_default <= Set rwb->enable_state (OFF) Submit_bio blk_mq_make_request rq_qos_throttle <= rwb->enable_state (OFF) scsi_remove_device sd_remove del_gendisk blk_unregister_queue elv_unregister_queue wbt_enable_default <= Set rwb->enable_state (ON) q_qos_track <= rwb->enable_state (ON) ^^^^^^ this request will mark WBT_TRACKED without inflight add and will lead to drop rqw->inflight to -1 in wbt_done() which will trigger IO hung. Fix this by move wbt_enable_default() from elv_unregister to bfq_exit_queue(). Only re-enable wbt when bfq exit. Fixes: 76a8040817b4b ("blk-wbt: make sure throttle is enabled properly") Remove oneline stale comment, and kill one oneshot local variable. Signed-off-by: Ming Lei <ming.lei@rehdat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/linux-block/20211214133103.551813-1-qiulaibin@huawei.com/ Signed-off-by: Laibin Qiu <qiulaibin@huawei.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-02-11block: partition include/linux/blk-cgroup.hMing Lei1-1/+1
Partition include/linux/blk-cgroup.h into two parts: one is public part, the other is block layer private part. Suggested by Christoph Hellwig. Signed-off-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20220211101149.2368042-4-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-11-29block: remove the e argument to elevator_exitChristoph Hellwig1-3/+5
All callers pass q->elevator. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20211123185312.1432157-4-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-11-29block: remove elevator_exitChristoph Hellwig1-1/+3
Open code elevator_exit in it's only caller, and rename __elevator_exit to elevator_exit. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20211123185312.1432157-3-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-11-17block: avoid to quiesce queue in elevator_init_mqMing Lei1-2/+8
elevator_init_mq() is only called before adding disk, when there isn't any FS I/O, only passthrough requests can be queued, so freezing queue plus canceling dispatch work is enough to drain any dispatch activities, then we can avoid synchronize_srcu() in blk_mq_quiesce_queue(). Long boot latency issue can be fixed in case of lots of disks added during booting. Fixes: 737eb78e82d5 ("block: Delay default elevator initialization") Reported-by: yangerkun <yangerkun@huawei.com> Cc: Damien Le Moal <damien.lemoal@wdc.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20211117115502.1600950-1-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-10-18blk-mq: Change shared sbitmap naming to shared tagsJohn Garry1-1/+1
Now that shared sbitmap support really means shared tags, rename symbols to match that. Signed-off-by: John Garry <john.garry@huawei.com> Link: https://lore.kernel.org/r/1633429419-228500-15-git-send-email-john.garry@huawei.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-10-18block: move elevator.h to block/Christoph Hellwig1-1/+1
Except for the features passed to blk_queue_required_elevator_features, elevator.h is only needed internally to the block layer. Move the ELEVATOR_F_* definitions to blkdev.h, and the move elevator.h to block/, dropping all the spurious includes outside of that. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Link: https://lore.kernel.org/r/20210920123328.1399408-13-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-09block: return ELEVATOR_DISCARD_MERGE if possibleMing Lei1-0/+3
When merging one bio to request, if they are discard IO and the queue supports multi-range discard, we need to return ELEVATOR_DISCARD_MERGE because both block core and related drivers(nvme, virtio-blk) doesn't handle mixed discard io merge(traditional IO merge together with discard merge) well. Fix the issue by returning ELEVATOR_DISCARD_MERGE in this situation, so both blk-mq and drivers just need to handle multi-range discard. Reported-by: Oleksandr Natalenko <oleksandr@natalenko.name> Signed-off-by: Ming Lei <ming.lei@redhat.com> Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name> Fixes: 2705dfb20947 ("block: fix discard request merge") Link: https://lore.kernel.org/r/20210729034226.1591070-1-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-09block: remove support for delayed queue registrationsChristoph Hellwig1-1/+0
Now that device mapper has been changed to register the disk once it is fully ready all this code is unused. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Mike Snitzer <snitzer@redhat.com> Link: https://lore.kernel.org/r/20210804094147.459763-9-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-05blk-mq: Introduce the BLK_MQ_F_NO_SCHED_BY_DEFAULT flagBart Van Assche1-0/+3
elevator_get_default() uses the following algorithm to select an I/O scheduler from inside add_disk(): - In case of a single hardware queue or if sharing hardware queues across multiple request queues (BLK_MQ_F_TAG_HCTX_SHARED), use mq-deadline. - Otherwise, use 'none'. This is a good choice for most but not for all block drivers. Make it possible to override the selection of mq-deadline with a new flag, namely BLK_MQ_F_NO_SCHED_BY_DEFAULT. Cc: Christoph Hellwig <hch@lst.de> Cc: Ming Lei <ming.lei@redhat.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Martijn Coenen <maco@android.com> Cc: Jaegeuk Kim <jaegeuk@kernel.org> Signed-off-by: Bart Van Assche <bvanassche@acm.org> Link: https://lore.kernel.org/r/20210805174200.3250718-2-bvanassche@acm.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-24blk: Fix lock inversion between ioc lock and bfqd lockJan Kara1-3/+8
Lockdep complains about lock inversion between ioc->lock and bfqd->lock: bfqd -> ioc: put_io_context+0x33/0x90 -> ioc->lock grabbed blk_mq_free_request+0x51/0x140 blk_put_request+0xe/0x10 blk_attempt_req_merge+0x1d/0x30 elv_attempt_insert_merge+0x56/0xa0 blk_mq_sched_try_insert_merge+0x4b/0x60 bfq_insert_requests+0x9e/0x18c0 -> bfqd->lock grabbed blk_mq_sched_insert_requests+0xd6/0x2b0 blk_mq_flush_plug_list+0x154/0x280 blk_finish_plug+0x40/0x60 ext4_writepages+0x696/0x1320 do_writepages+0x1c/0x80 __filemap_fdatawrite_range+0xd7/0x120 sync_file_range+0xac/0xf0 ioc->bfqd: bfq_exit_icq+0xa3/0xe0 -> bfqd->lock grabbed put_io_context_active+0x78/0xb0 -> ioc->lock grabbed exit_io_context+0x48/0x50 do_exit+0x7e9/0xdd0 do_group_exit+0x54/0xc0 To avoid this inversion we change blk_mq_sched_try_insert_merge() to not free the merged request but rather leave that upto the caller similarly to blk_mq_sched_try_merge(). And in bfq_insert_requests() we make sure to free all the merged requests after dropping bfqd->lock. Fixes: aee69d78dec0 ("block, bfq: introduce the BFQ-v0 I/O scheduler as an extra scheduler") Reviewed-by: Ming Lei <ming.lei@redhat.com> Acked-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jan Kara <jack@suse.cz> Link: https://lore.kernel.org/r/20210623093634.27879-3-jack@suse.cz Signed-off-by: Jens Axboe <axboe@kernel.dk>
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