kernel/include/linux/blk-mq.h, branch linux-5.5.y

blk-mq: Delete blk_mq_has_free_tags() and blk_mq_can_queue()

2019-11-13T19:50:38Z

These functions are not referenced, so delete them. Signed-off-by: John Garry Signed-off-by: Jens Axboe

blk-mq: Make blk_mq_run_hw_queue() return void

2019-11-01T14:42:41Z

Since commit 97889f9ac24f ("blk-mq: remove synchronize_rcu() from blk_mq_del_queue_tag_set()"), the return value of blk_mq_run_hw_queue() is never checked, so make it return void, which very marginally simplifies the code. Reviewed-by: Bob Liu Signed-off-by: John Garry Signed-off-by: Jens Axboe

blk-mq: fill header with kernel-doc

2019-10-25T20:28:10Z

Insert documentation for structs, enums and functions at header file. Format existing and new comments at struct blk_mq_ops as kernel-doc comments. Reviewed-by: Bart Van Assche Signed-off-by: André Almeida Signed-off-by: Jens Axboe

blk-mq: Inline status checkers

2019-10-07T14:31:59Z

blk_mq_request_completed() and blk_mq_request_started() are short, inline it. Signed-off-by: Pavel Begunkov Signed-off-by: Jens Axboe

block: Document all members of blk_mq_tag_set and bkl_mq_queue_map

2019-10-07T14:31:59Z

The meaning of several member variables of these two data structures is nontrivial. Hence document all member variables using the kernel-doc syntax. Cc: Christoph Hellwig Cc: Ming Lei Cc: Hannes Reinecke Cc: Johannes Thumshirn Signed-off-by: Bart Van Assche Signed-off-by: Jens Axboe

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