user/sven/linux.git/include/linux/blk-mq.h, branch v5.4.249

block: Delay default elevator initialization

2019-09-06T01:52:34Z

When elevator_init_mq() is called from blk_mq_init_allocated_queue(), the only information known about the device is the number of hardware queues as the block device scan by the device driver is not completed yet for most drivers. The device type and elevator required features are not set yet, preventing to correctly select the default elevator most suitable for the device. This currently affects all multi-queue zoned block devices which default to the "none" elevator instead of the required "mq-deadline" elevator. These drives currently include host-managed SMR disks connected to a smartpqi HBA and null_blk block devices with zoned mode enabled. Upcoming NVMe Zoned Namespace devices will also be affected. Fix this by adding the boolean elevator_init argument to blk_mq_init_allocated_queue() to control the execution of elevator_init_mq(). Two cases exist: 1) elevator_init = false is used for calls to blk_mq_init_allocated_queue() within blk_mq_init_queue(). In this case, a call to elevator_init_mq() is added to __device_add_disk(), resulting in the delayed initialization of the queue elevator after the device driver finished probing the device information. This effectively allows elevator_init_mq() access to more information about the device. 2) elevator_init = true preserves the current behavior of initializing the elevator directly from blk_mq_init_allocated_queue(). This case is used for the special request based DM devices where the device gendisk is created before the queue initialization and device information (e.g. queue limits) is already known when the queue initialization is executed. Additionally, to make sure that the elevator initialization is never done while requests are in-flight (there should be none when the device driver calls device_add_disk()), freeze and quiesce the device request queue before calling blk_mq_init_sched() in elevator_init_mq(). Reviewed-by: Ming Lei Signed-off-by: Damien Le Moal Signed-off-by: Jens Axboe

block: Remove blk_mq_register_dev()

2019-08-27T16:40:19Z

This function has no callers. Hence remove it. Cc: Christoph Hellwig Cc: Ming Lei Cc: Hannes Reinecke Signed-off-by: Bart Van Assche Signed-off-by: Jens Axboe

blk-mq: add callback of .cleanup_rq

2019-08-05T03:42:06Z

SCSI maintains its own driver private data hooked off of each SCSI request, and the pridate data won't be freed after scsi_queue_rq() returns BLK_STS_RESOURCE or BLK_STS_DEV_RESOURCE. An upper layer driver (e.g. dm-rq) may need to retry these SCSI requests, before SCSI has fully dispatched them, due to a lower level SCSI driver's resource limitation identified in scsi_queue_rq(). Currently SCSI's per-request private data is leaked when the upper layer driver (dm-rq) frees and then retries these requests in response to BLK_STS_RESOURCE or BLK_STS_DEV_RESOURCE returns from scsi_queue_rq(). This usecase is so specialized that it doesn't warrant training an existing blk-mq interface (e.g. blk_mq_free_request) to allow SCSI to account for freeing its driver private data -- doing so would add an extra branch for handling a special case that all other consumers of SCSI (and blk-mq) won't ever need to worry about. So the most pragmatic way forward is to delegate freeing SCSI driver private data to the upper layer driver (dm-rq). Do so by adding new .cleanup_rq callback and calling a new blk_mq_cleanup_rq() method from dm-rq. A following commit will implement the .cleanup_rq() hook in scsi_mq_ops. Cc: Ewan D. Milne Cc: Bart Van Assche Cc: Hannes Reinecke Cc: Christoph Hellwig Cc: Mike Snitzer Cc: dm-devel@redhat.com Cc: Fixes: 396eaf21ee17 ("blk-mq: improve DM's blk-mq IO merging via blk_insert_cloned_request feedback") Signed-off-by: Ming Lei Signed-off-by: Jens Axboe

blk-mq: remove blk_mq_complete_request_sync

2019-08-05T03:41:29Z

blk_mq_tagset_wait_completed_request() has been applied for waiting for completed request's fn, so not necessary to use blk_mq_complete_request_sync() any more. Cc: Max Gurtovoy Cc: Sagi Grimberg Cc: Keith Busch Cc: Christoph Hellwig Reviewed-by: Sagi Grimberg Signed-off-by: Ming Lei Signed-off-by: Jens Axboe

blk-mq: introduce blk_mq_tagset_wait_completed_request()

2019-08-05T03:41:29Z

blk-mq may schedule to call queue's complete function on remote CPU via IPI, but doesn't provide any way to synchronize the request's complete fn. The current queue freeze interface can't provide the synchonization because aborted requests stay at blk-mq queues during EH. In some driver's EH(such as NVMe), hardware queue's resource may be freed & re-allocated. If the completed request's complete fn is run finally after the hardware queue's resource is released, kernel crash will be triggered. Prepare for fixing this kind of issue by introducing blk_mq_tagset_wait_completed_request(). Cc: Max Gurtovoy Cc: Sagi Grimberg Cc: Keith Busch Cc: Christoph Hellwig Reviewed-by: Sagi Grimberg Signed-off-by: Ming Lei Signed-off-by: Jens Axboe

blk-mq: introduce blk_mq_request_completed()

2019-08-05T03:41:29Z

NVMe needs this function to decide if one request to be aborted has been completed in normal IO path already. So introduce it. Cc: Max Gurtovoy Cc: Sagi Grimberg Cc: Keith Busch Cc: Christoph Hellwig Reviewed-by: Sagi Grimberg Signed-off-by: Ming Lei Signed-off-by: Jens Axboe

block: remove the bi_phys_segments field in struct bio

2019-06-20T16:29:22Z

We only need the number of segments in the blk-mq submission path. Remove the field from struct bio, and return it from a variant of blk_queue_split instead of that it can passed as an argument to those functions that need the value. This also means we stop recounting segments except for cloning and partial segments. To keep the number of arguments in this how path down remove pointless struct request_queue arguments from any of the functions that had it and grew a nr_segs argument. Signed-off-by: Christoph Hellwig Signed-off-by: Jens Axboe

blk-mq: always free hctx after request queue is freed

2019-05-04T13:24:08Z

In normal queue cleanup path, hctx is released after request queue is freed, see blk_mq_release(). However, in __blk_mq_update_nr_hw_queues(), hctx may be freed because of hw queues shrinking. This way is easy to cause use-after-free, because: one implicit rule is that it is safe to call almost all block layer APIs if the request queue is alive; and one hctx may be retrieved by one API, then the hctx can be freed by blk_mq_update_nr_hw_queues(); finally use-after-free is triggered. Fixes this issue by always freeing hctx after releasing request queue. If some hctxs are removed in blk_mq_update_nr_hw_queues(), introduce a per-queue list to hold them, then try to resuse these hctxs if numa node is matched. Cc: Dongli Zhang Cc: James Smart Cc: Bart Van Assche Cc: linux-scsi@vger.kernel.org, Cc: Martin K . Petersen , Cc: Christoph Hellwig , Cc: James E . J . Bottomley , Reviewed-by: Hannes Reinecke Tested-by: James Smart Signed-off-by: Ming Lei Signed-off-by: Jens Axboe

blk-mq: introduce blk_mq_complete_request_sync()

2019-04-10T15:57:33Z

In NVMe's error handler, follows the typical steps of tearing down hardware for recovering controller: 1) stop blk_mq hw queues 2) stop the real hw queues 3) cancel in-flight requests via blk_mq_tagset_busy_iter(tags, cancel_request, ...) cancel_request(): mark the request as abort blk_mq_complete_request(req); 4) destroy real hw queues However, there may be race between #3 and #4, because blk_mq_complete_request() may run q->mq_ops->complete(rq) remotelly and asynchronously, and ->complete(rq) may be run after #4. This patch introduces blk_mq_complete_request_sync() for fixing the above race. Cc: Sagi Grimberg Cc: Bart Van Assche Cc: James Smart Cc: linux-nvme@lists.infradead.org Reviewed-by: Keith Busch Reviewed-by: Christoph Hellwig Signed-off-by: Ming Lei Signed-off-by: Jens Axboe

block: Unexport blk_mq_add_to_requeue_list()

2019-03-20T20:19:36Z

This function is not used outside the block layer core. Hence unexport it. Cc: Christoph Hellwig Cc: Ming Lei Signed-off-by: Bart Van Assche Signed-off-by: Jens Axboe