#
99a9476b |
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07-Apr-2024 |
Damien Le Moal <dlemoal@kernel.org> |
block: Do not special-case plugging of zone write operations With the block layer zone write plugging being automatically done for any write operation to a zone of a zoned block device, a regular request plugging handled through current->plug can only ever see at most a single write request per zone. In such case, any potential reordering of the plugged requests will be harmless. We can thus remove the special casing for write operations to zones and have these requests plugged as well. This allows removing the function blk_mq_plug and instead directly using current->plug where needed. 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/20240408014128.205141-29-dlemoal@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
217b613a |
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13-Sep-2023 |
Chengming Zhou <zhouchengming@bytedance.com> |
blk-mq: update driver tags request table when start request Now we update driver tags request table in blk_mq_get_driver_tag(), so the driver that support queue_rqs() have to update that inflight table by itself. Move it to blk_mq_start_request(), which is a better place where we setup the deadline for request timeout check. And it's just where the request becomes inflight. Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20230913151616.3164338-5-chengming.zhou@linux.dev Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
b8643d68 |
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13-Sep-2023 |
Chengming Zhou <zhouchengming@bytedance.com> |
blk-mq: account active requests when get driver tag There is a limit that batched queue_rqs() can't work on shared tags queue, since the account of active requests can't be done there. Now we account the active requests only in blk_mq_get_driver_tag(), which is not the time we get driver tag actually (with none elevator). To support batched queue_rqs() on shared tags queue, we move the account of active requests to where we get the driver tag: 1. none elevator: blk_mq_get_tags() and blk_mq_get_tag() 2. other elevator: __blk_mq_alloc_driver_tag() This is clearer and match with the unaccount side, which just happen when we put the driver tag. The other good point is that we don't need RQF_MQ_INFLIGHT trick anymore, which used to avoid double account of flush request. Now we only account when actually get the driver tag, so all is good. We will remove RQF_MQ_INFLIGHT in the next patch. Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20230913151616.3164338-2-chengming.zhou@linux.dev Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
4f1731df |
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09-Jun-2023 |
Yu Kuai <yukuai3@huawei.com> |
blk-mq: fix potential io hang by wrong 'wake_batch' In __blk_mq_tag_busy/idle(), updating 'active_queues' and calculating 'wake_batch' is not atomic: t1: t2: _blk_mq_tag_busy blk_mq_tag_busy inc active_queues // assume 1->2 inc active_queues // 2 -> 3 blk_mq_update_wake_batch // calculate based on 3 blk_mq_update_wake_batch /* calculate based on 2, while active_queues is actually 3. */ Fix this problem by protecting them wih 'tags->lock', this is not a hot path, so performance should not be concerned. And now that all writers are inside the lock, switch 'actives_queues' from atomic to unsigned int. Fixes: 180dccb0dba4 ("blk-mq: fix tag_get wait task can't be awakened") Signed-off-by: Yu Kuai <yukuai3@huawei.com> Reviewed-by: Jan Kara <jack@suse.cz> Link: https://lore.kernel.org/r/20230610023043.2559121-1-yukuai1@huaweicloud.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
9a67aa52 |
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18-May-2023 |
Christoph Hellwig <hch@lst.de> |
blk-mq: don't use the requeue list to queue flush commands Currently both requeues of commands that were already sent to the driver and flush commands submitted from the flush state machine share the same requeue_list struct request_queue, despite requeues doing head insertions and flushes not. Switch to using two separate lists instead. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Link: https://lore.kernel.org/r/20230519044050.107790-8-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
360f2648 |
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18-May-2023 |
Christoph Hellwig <hch@lst.de> |
blk-mq: defer to the normal submission path for non-flush flush commands If blk_insert_flush decides that a command does not need to use the flush state machine, return false and let blk_mq_submit_bio handle it the normal way (including using an I/O scheduler) instead of doing a bypass insert. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Link: https://lore.kernel.org/r/20230519044050.107790-4-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
dd6216bb |
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17-May-2023 |
Christoph Hellwig <hch@lst.de> |
blk-mq: make sure elevator callbacks aren't called for passthrough request In case of q->elevator, passthrough request can still be marked as RQF_ELV, so some elevator callbacks will be called for them. Fix this by splitting RQF_SCHED_TAGS, which is set for all requests that are issued on a queue that uses an I/O scheduler, and RQF_USE_SCHED for non-flush, non-passthrough requests on such a queue. Roughly based on two different patches from Ming Lei <ming.lei@redhat.com>. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20230518053101.760632-4-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
b12e5c6c |
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13-Apr-2023 |
Christoph Hellwig <hch@lst.de> |
blk-mq: pass a flags argument to blk_mq_add_to_requeue_list Replace the boolean at_head argument with the same flags that are already passed to blk_mq_insert_request. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Link: https://lore.kernel.org/r/20230413064057.707578-21-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
2b597613 |
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13-Apr-2023 |
Christoph Hellwig <hch@lst.de> |
blk-mq: pass a flags argument to blk_mq_request_bypass_insert Replace the boolean at_head argument with the same flags that are already passed to blk_mq_insert_request. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Link: https://lore.kernel.org/r/20230413064057.707578-19-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
710fa378 |
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13-Apr-2023 |
Christoph Hellwig <hch@lst.de> |
blk-mq: pass a flags argument to blk_mq_insert_request Replace the at_head bool with a flags argument that so far only contains a single BLK_MQ_INSERT_AT_HEAD value. This makes it much easier to grep for head insertions into the blk-mq dispatch queues. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Link: https://lore.kernel.org/r/20230413064057.707578-18-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
214a4418 |
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13-Apr-2023 |
Christoph Hellwig <hch@lst.de> |
blk-mq: don't kick the requeue_list in blk_mq_add_to_requeue_list blk_mq_add_to_requeue_list takes a bool parameter to control how to kick the requeue list at the end of the function. Move the call to blk_mq_kick_requeue_list to the callers that want it instead. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Link: https://lore.kernel.org/r/20230413064057.707578-17-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
2394395c |
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13-Apr-2023 |
Christoph Hellwig <hch@lst.de> |
blk-mq: don't run the hw_queue from blk_mq_request_bypass_insert blk_mq_request_bypass_insert takes a bool parameter to control how to run the queue at the end of the function. Move the blk_mq_run_hw_queue call to the callers that want it instead. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Link: https://lore.kernel.org/r/20230413064057.707578-16-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
a88db1e0 |
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13-Apr-2023 |
Christoph Hellwig <hch@lst.de> |
blk-mq: fold __blk_mq_insert_request into blk_mq_insert_request There is no good point in keeping the __blk_mq_insert_request around for two function calls and a singler caller. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Link: https://lore.kernel.org/r/20230413064057.707578-8-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
05a93117 |
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13-Apr-2023 |
Christoph Hellwig <hch@lst.de> |
blk-mq: fold blk_mq_sched_insert_requests into blk_mq_dispatch_plug_list blk_mq_dispatch_plug_list is the only caller of blk_mq_sched_insert_requests, and it makes sense to just fold it there as blk_mq_sched_insert_requests isn't specific to I/O schedulers despite the name. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Link: https://lore.kernel.org/r/20230413064057.707578-6-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
94aa228c |
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13-Apr-2023 |
Christoph Hellwig <hch@lst.de> |
blk-mq: move more logic into blk_mq_insert_requests Move all logic related to the direct insert (including the call to blk_mq_run_hw_queue) into blk_mq_insert_requests to streamline the code flow up a bit, and to allow marking blk_mq_try_issue_list_directly static. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Link: https://lore.kernel.org/r/20230413064057.707578-5-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
90110e04 |
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13-Apr-2023 |
Christoph Hellwig <hch@lst.de> |
blk-mq: include <linux/blk-mq.h> in block/blk-mq.h block/blk-mq.h needs various definitions from <linux/blk-mq.h>, include it there instead of relying on the source files to include both. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Link: https://lore.kernel.org/r/20230413064057.707578-4-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
bebe84eb |
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13-Apr-2023 |
Christoph Hellwig <hch@lst.de> |
blk-mq: remove blk-mq-tag.h blk-mq-tag.h is always included by blk-mq.h, and causes recursive inclusion hell with further changes. Just merge it into blk-mq.h instead. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Link: https://lore.kernel.org/r/20230413064057.707578-3-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
00e885ef |
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09-Mar-2023 |
Chris Leech <cleech@redhat.com> |
blk-mq: fix "bad unlock balance detected" on q->srcu in __blk_mq_run_dispatch_ops The 'q' parameter of the macro __blk_mq_run_dispatch_ops may not be one local variable, such as, it is rq->q, then request queue pointed by this variable could be changed to another queue in case of BLK_MQ_F_TAG_QUEUE_SHARED after 'dispatch_ops' returns, then 'bad unlock balance' is triggered. Fixes the issue by adding one local variable for doing srcu lock/unlock. Fixes: 2a904d00855f ("blk-mq: remove hctx_lock and hctx_unlock") Cc: Marco Patalano <mpatalan@redhat.com> Signed-off-by: Chris Leech <cleech@redhat.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20230310010913.1014789-1-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
80bd4a7a |
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01-Nov-2022 |
Christoph Hellwig <hch@lst.de> |
blk-mq: move the srcu_struct used for quiescing to the tagset All I/O submissions have fairly similar latencies, and a tagset-wide quiesce is a fairly common operation. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Keith Busch <kbusch@kernel.org> Reviewed-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Chao Leng <lengchao@huawei.com> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com> Link: https://lore.kernel.org/r/20221101150050.3510-12-hch@lst.de [axboe: fix whitespace] Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
8cafdb5a |
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29-Sep-2022 |
Pankaj Raghav <p.raghav@samsung.com> |
block: adapt blk_mq_plug() to not plug for writes that require a zone lock The current implementation of blk_mq_plug() disables plugging for all operations that involves a transfer to the device as we just check if the last bit in op_is_write() function. Modify blk_mq_plug() to disable plugging only for REQ_OP_WRITE and REQ_OP_WRITE_ZEROS as they might require a zone lock. Suggested-by: Christoph Hellwig <hch@lst.de> Suggested-by: Damien Le Moal <damien.lemoal@opensource.wdc.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Pankaj Raghav <p.raghav@samsung.com> Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Link: https://lore.kernel.org/r/20220929074745.103073-2-p.raghav@samsung.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
16458cf3 |
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14-Jul-2022 |
Bart Van Assche <bvanassche@acm.org> |
block: Use the new blk_opf_t type Use the new blk_opf_t type for arguments and variables that represent request flags or a bitwise combination of a request operation and request flags. Rename the function arguments and also a structure member that hold a request operation and flags from 'rw' into 'opf'. This patch does not change any functionality. Cc: Christoph Hellwig <hch@lst.de> Cc: Ming Lei <ming.lei@redhat.com> Cc: Hannes Reinecke <hare@suse.de> Cc: Damien Le Moal <damien.lemoal@wdc.com> Cc: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Bart Van Assche <bvanassche@acm.org> Link: https://lore.kernel.org/r/20220714180729.1065367-7-bvanassche@acm.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
6deacb3b |
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06-Jul-2022 |
Christoph Hellwig <hch@lst.de> |
block: simplify blk_mq_plug Drop the unused q argument, and invert the check to move the exception into a branch and the regular path as the normal return. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com> Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Link: https://lore.kernel.org/r/20220706070350.1703384-5-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
edd1dbc8 |
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06-Jul-2022 |
Christoph Hellwig <hch@lst.de> |
block: use bdev_is_zoned instead of open coding it Use bdev_is_zoned in all places where a block_device is available instead of open coding it. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com> Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Link: https://lore.kernel.org/r/20220706070350.1703384-4-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
8682b92e |
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28-Jun-2022 |
Christoph Hellwig <hch@lst.de> |
blk-mq: cleanup disk sysfs registration Pass a gendisk to the sysfs register/unregister functions and give them descriptive names. Also move the unregistration helper next to the one doing the registration. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Link: https://lore.kernel.org/r/20220628171850.1313069-7-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
eaa870f9 |
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28-Jun-2022 |
Christoph Hellwig <hch@lst.de> |
blk-mq: rename blk_mq_sysfs_{,un}register Add a _hctx postfix to better describe what the functions do, match the debugfs equivalents and release the old names for functions that should be using them. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Link: https://lore.kernel.org/r/20220628171850.1313069-6-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
7e923f40 |
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15-Jun-2022 |
Bart Van Assche <bvanassche@acm.org> |
block: Rename a blk_mq_map_queue() argument Before the introduction of blk_mq_get_hctx_type(), blk_mq_map_queue() only used the flags from its second argument. Since the introduction of blk_mq_get_hctx_type(), blk_mq_map_queue() uses both the operation and the flags encoded in that argument. Rename the second argument of blk_mq_map_queue() to make this clear. Cc: Christoph Hellwig <hch@lst.de> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Bart Van Assche <bvanassche@acm.org> Link: https://lore.kernel.org/r/20220615225549.1054905-3-bvanassche@acm.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
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4e5cc99e |
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08-Mar-2022 |
Ming Lei <ming.lei@redhat.com> |
blk-mq: manage hctx map via xarray First code becomes more clean by switching to xarray from plain array. Second use-after-free on q->queue_hw_ctx can be fixed because queue_for_each_hw_ctx() may be run when updating nr_hw_queues is in-progress. With this patch, q->hctx_table is defined as xarray, and this structure will share same lifetime with request queue, so queue_for_each_hw_ctx() can use q->hctx_table to lookup hctx reliably. Reported-by: Yu Kuai <yukuai3@huawei.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20220308073219.91173-7-ming.lei@redhat.com [axboe: fix blk_mq_hw_ctx forward declaration] Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
41adf531 |
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06-Dec-2021 |
Ming Lei <ming.lei@redhat.com> |
blk-mq: don't run might_sleep() if the operation needn't blocking The operation protected via blk_mq_run_dispatch_ops() in blk_mq_run_hw_queue won't sleep, so don't run might_sleep() for it. Reported-and-tested-by: Marek Szyprowski <m.szyprowski@samsung.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
bcc330f4 |
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03-Dec-2021 |
Ming Lei <ming.lei@redhat.com> |
blk-mq: pass request queue to blk_mq_run_dispatch_ops We have switched to allocate srcu into request queue, so it is fine to pass request queue to blk_mq_run_dispatch_ops(). Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20211203131534.3668411-4-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
704b914f |
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03-Dec-2021 |
Ming Lei <ming.lei@redhat.com> |
blk-mq: move srcu from blk_mq_hw_ctx to request_queue In case of BLK_MQ_F_BLOCKING, per-hctx srcu is used to protect dispatch critical area. However, this srcu instance stays at the end of hctx, and it often takes standalone cacheline, often cold. Inside srcu_read_lock() and srcu_read_unlock(), WRITE is always done on the indirect percpu variable which is allocated from heap instead of being embedded, srcu->srcu_idx is read only in srcu_read_lock(). It doesn't matter if srcu structure stays in hctx or request queue. So switch to per-request-queue srcu for protecting dispatch, and this way simplifies quiesce a lot, not mention quiesce is always done on the request queue wide. Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20211203131534.3668411-3-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
2a904d00 |
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03-Dec-2021 |
Ming Lei <ming.lei@redhat.com> |
blk-mq: remove hctx_lock and hctx_unlock Remove hctx_lock and hctx_unlock, and add one helper of blk_mq_run_dispatch_ops() to run code block defined in dispatch_ops with rcu/srcu read held. Compared with hctx_lock()/hctx_unlock(): 1) remove 2 branch to 1, so we just need to check (hctx->flags & BLK_MQ_F_BLOCKING) once when running one dispatch_ops 2) srcu_idx needn't to be touched in case of non-blocking 3) might_sleep_if() can be moved to the blocking branch Also put the added blk_mq_run_dispatch_ops() in private header, so that the following patch can use it out of blk-mq.c. Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20211203131534.3668411-2-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
06c8c691 |
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16-Nov-2021 |
Christoph Hellwig <hch@lst.de> |
block: move request based cloning helpers to blk-mq.c Keep all the request based code together. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Link: https://lore.kernel.org/r/20211117061404.331732-6-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
2a19b28f |
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15-Nov-2021 |
Ming Lei <ming.lei@redhat.com> |
blk-mq: cancel blk-mq dispatch work in both blk_cleanup_queue and disk_release() For avoiding to slow down queue destroy, we don't call blk_mq_quiesce_queue() in blk_cleanup_queue(), instead of delaying to cancel dispatch work in blk_release_queue(). However, this way has caused kernel oops[1], reported by Changhui. The log shows that scsi_device can be freed before running blk_release_queue(), which is expected too since scsi_device is released after the scsi disk is closed and the scsi_device is removed. Fixes the issue by canceling blk-mq dispatch work in both blk_cleanup_queue() and disk_release(): 1) when disk_release() is run, the disk has been closed, and any sync dispatch activities have been done, so canceling dispatch work is enough to quiesce filesystem I/O dispatch activity. 2) in blk_cleanup_queue(), we only focus on passthrough request, and passthrough request is always explicitly allocated & freed by its caller, so once queue is frozen, all sync dispatch activity for passthrough request has been done, then it is enough to just cancel dispatch work for avoiding any dispatch activity. [1] kernel panic log [12622.769416] BUG: kernel NULL pointer dereference, address: 0000000000000300 [12622.777186] #PF: supervisor read access in kernel mode [12622.782918] #PF: error_code(0x0000) - not-present page [12622.788649] PGD 0 P4D 0 [12622.791474] Oops: 0000 [#1] PREEMPT SMP PTI [12622.796138] CPU: 10 PID: 744 Comm: kworker/10:1H Kdump: loaded Not tainted 5.15.0+ #1 [12622.804877] Hardware name: Dell Inc. PowerEdge R730/0H21J3, BIOS 1.5.4 10/002/2015 [12622.813321] Workqueue: kblockd blk_mq_run_work_fn [12622.818572] RIP: 0010:sbitmap_get+0x75/0x190 [12622.823336] Code: 85 80 00 00 00 41 8b 57 08 85 d2 0f 84 b1 00 00 00 45 31 e4 48 63 cd 48 8d 1c 49 48 c1 e3 06 49 03 5f 10 4c 8d 6b 40 83 f0 01 <48> 8b 33 44 89 f2 4c 89 ef 0f b6 c8 e8 fa f3 ff ff 83 f8 ff 75 58 [12622.844290] RSP: 0018:ffffb00a446dbd40 EFLAGS: 00010202 [12622.850120] RAX: 0000000000000001 RBX: 0000000000000300 RCX: 0000000000000004 [12622.858082] RDX: 0000000000000006 RSI: 0000000000000082 RDI: ffffa0b7a2dfe030 [12622.866042] RBP: 0000000000000004 R08: 0000000000000001 R09: ffffa0b742721334 [12622.874003] R10: 0000000000000008 R11: 0000000000000008 R12: 0000000000000000 [12622.881964] R13: 0000000000000340 R14: 0000000000000000 R15: ffffa0b7a2dfe030 [12622.889926] FS: 0000000000000000(0000) GS:ffffa0baafb40000(0000) knlGS:0000000000000000 [12622.898956] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [12622.905367] CR2: 0000000000000300 CR3: 0000000641210001 CR4: 00000000001706e0 [12622.913328] Call Trace: [12622.916055] <TASK> [12622.918394] scsi_mq_get_budget+0x1a/0x110 [12622.922969] __blk_mq_do_dispatch_sched+0x1d4/0x320 [12622.928404] ? pick_next_task_fair+0x39/0x390 [12622.933268] __blk_mq_sched_dispatch_requests+0xf4/0x140 [12622.939194] blk_mq_sched_dispatch_requests+0x30/0x60 [12622.944829] __blk_mq_run_hw_queue+0x30/0xa0 [12622.949593] process_one_work+0x1e8/0x3c0 [12622.954059] worker_thread+0x50/0x3b0 [12622.958144] ? rescuer_thread+0x370/0x370 [12622.962616] kthread+0x158/0x180 [12622.966218] ? set_kthread_struct+0x40/0x40 [12622.970884] ret_from_fork+0x22/0x30 [12622.974875] </TASK> [12622.977309] Modules linked in: scsi_debug rpcsec_gss_krb5 auth_rpcgss nfsv4 dns_resolver nfs lockd grace fscache netfs sunrpc dm_multipath intel_rapl_msr intel_rapl_common dell_wmi_descriptor sb_edac rfkill video x86_pkg_temp_thermal intel_powerclamp dcdbas coretemp kvm_intel kvm mgag200 irqbypass i2c_algo_bit rapl drm_kms_helper ipmi_ssif intel_cstate intel_uncore syscopyarea sysfillrect sysimgblt fb_sys_fops pcspkr cec mei_me lpc_ich mei ipmi_si ipmi_devintf ipmi_msghandler acpi_power_meter drm fuse xfs libcrc32c sr_mod cdrom sd_mod t10_pi sg ixgbe ahci libahci crct10dif_pclmul crc32_pclmul crc32c_intel libata megaraid_sas ghash_clmulni_intel tg3 wdat_wdt mdio dca wmi dm_mirror dm_region_hash dm_log dm_mod [last unloaded: scsi_debug] Reported-by: ChanghuiZhong <czhong@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: "Martin K. Petersen" <martin.petersen@oracle.com> Cc: Bart Van Assche <bvanassche@acm.org> Cc: linux-scsi@vger.kernel.org Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20211116014343.610501-1-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
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b637108a |
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12-Nov-2021 |
Ming Lei <ming.lei@redhat.com> |
blk-mq: fix filesystem I/O request allocation submit_bio_checks() may update bio->bi_opf, so we have to initialize blk_mq_alloc_data.cmd_flags with bio->bi_opf after submit_bio_checks() returns when allocating new request. In case of using cached request, fallback to allocate new request if cached rq isn't compatible with the incoming bio, otherwise change rq->cmd_flags with incoming bio->bi_opf. Fixes: 900e080752025f00 ("block: move queue enter logic into blk_mq_submit_bio()") Reported-by: Geert Uytterhoeven <geert@linux-m68k.org> Tested-by: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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ecaf97f4 |
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09-Nov-2021 |
Jens Axboe <axboe@kernel.dk> |
block: use enum type for blk_mq_alloc_data->rq_flags kernel test robot reports that we now trigger some sparse warnings: block/blk-mq.h:169:32: sparse: sparse: restricted req_flags_t degrades to integer block/blk-mq.h:169:32: sparse: sparse: restricted req_flags_t degrades to integer block/blk-mq.h:169:32: sparse: sparse: restricted req_flags_t degrades to integer which is due to ->rq_flags being an unsigned int, rather than the stronger type req_flags_t enum. Change the type to req_flags_t to silence this warning. Fixes: 56f8da642bd8 ("block: add rq_flags to struct blk_mq_alloc_data") Reported-by: kernel test robot <lkp@intel.com> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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3b87c6ea |
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02-Nov-2021 |
Ming Lei <ming.lei@redhat.com> |
blk-mq: update hctx->nr_active in blk_mq_end_request_batch() In case of shared tags and none io sched, batched completion still may be run into, and hctx->nr_active is accounted when getting driver tag, so it has to be updated in blk_mq_end_request_batch(). Otherwise, hctx->nr_active may become same with queue depth, then hctx_may_queue() always return false, then io hang is caused. Fixes the issue by updating the counter in batched way. Reported-by: Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com> Fixes: f794f3351f26 ("block: add support for blk_mq_end_request_batch()") Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20211102153619.3627505-4-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
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56f8da64 |
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19-Oct-2021 |
Jens Axboe <axboe@kernel.dk> |
block: add rq_flags to struct blk_mq_alloc_data There's a hole here we can use, and it's faster to set this earlier rather than need to check q->elevator multiple times. Signed-off-by: Jens Axboe <axboe@kernel.dk> Link: https://lore.kernel.org/r/20211019153300.623322-2-axboe@kernel.dk Signed-off-by: Jens Axboe <axboe@kernel.dk>
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dbb6f764 |
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20-Oct-2021 |
Christoph Hellwig <hch@lst.de> |
blk-mq: move blk_mq_flush_plug_list to block/blk-mq.h This helper is internal to the block layer. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20211020144119.142582-3-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
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a808a9d5 |
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13-Oct-2021 |
Jens Axboe <axboe@kernel.dk> |
block: inline fast path of driver tag allocation If we don't use an IO scheduler or have shared tags, then we don't need to call into this external function at all. This saves ~2% for such a setup. Signed-off-by: Jens Axboe <axboe@kernel.dk>
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5a72e899 |
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12-Oct-2021 |
Jens Axboe <axboe@kernel.dk> |
block: add a struct io_comp_batch argument to fops->iopoll() struct io_comp_batch contains a list head and a completion handler, which will allow completions to more effciently completed batches of IO. For now, no functional changes in this patch, we just define the io_comp_batch structure and add the argument to the file_operations iopoll handler. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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9a14d6ce |
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16-Oct-2021 |
Jens Axboe <axboe@kernel.dk> |
block: remove debugfs blk_mq_ctx dispatched/merged/completed attributes These were added as part of early days debugging for blk-mq, and they are not really useful anymore. Rather than spend cycles updating them, just get rid of them. As a bonus, this shrinks the per-cpu software queue size from 256b to 192b. That's a whole cacheline less. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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3e08773c |
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12-Oct-2021 |
Christoph Hellwig <hch@lst.de> |
block: switch polling to be bio based Replace the blk_poll interface that requires the caller to keep a queue and cookie from the submissions with polling based on the bio. Polling for the bio itself leads to a few advantages: - the cookie construction can made entirely private in blk-mq.c - the caller does not need to remember the request_queue and cookie separately and thus sidesteps their lifetime issues - keeping the device and the cookie inside the bio allows to trivially support polling BIOs remapping by stacking drivers - a lot of code to propagate the cookie back up the submission path can be removed entirely. Signed-off-by: Christoph Hellwig <hch@lst.de> Tested-by: Mark Wunderlich <mark.wunderlich@intel.com> Link: https://lore.kernel.org/r/20211012111226.760968-15-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
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6ce913fe |
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12-Oct-2021 |
Christoph Hellwig <hch@lst.de> |
block: rename REQ_HIPRI to REQ_POLLED Unlike the RWF_HIPRI userspace ABI which is intentionally kept vague, the bio flag is specific to the polling implementation, so rename and document it properly. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Tested-by: Mark Wunderlich <mark.wunderlich@intel.com> Link: https://lore.kernel.org/r/20211012111226.760968-12-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
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47c122e3 |
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06-Oct-2021 |
Jens Axboe <axboe@kernel.dk> |
block: pre-allocate requests if plug is started and is a batch The caller typically has a good (or even exact) idea of how many requests it needs to submit. We can make the request/tag allocation a lot more efficient if we just allocate N requests/tags upfront when we queue the first bio from the batch. Provide a new plug start helper that allows the caller to specify how many IOs are expected. This sets plug->nr_ios, and we can use that for smarter request allocation. The plug provides a holding spot for requests, and request allocation will check it before calling into the normal request allocation path. The blk_finish_plug() is called, check if there are unused requests and free them. This should not happen in normal operations. The exception is if we get merging, then we may be left with requests that need freeing when done. This raises the per-core performance on my setup from ~5.8M to ~6.1M IOPS. Signed-off-by: Jens Axboe <axboe@kernel.dk>
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079a2e3e |
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05-Oct-2021 |
John Garry <john.garry@huawei.com> |
blk-mq: Change shared sbitmap naming to shared tags 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>
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e155b0c2 |
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05-Oct-2021 |
John Garry <john.garry@huawei.com> |
blk-mq: Use shared tags for shared sbitmap support Currently we use separate sbitmap pairs and active_queues atomic_t for shared sbitmap support. However a full sets of static requests are used per HW queue, which is quite wasteful, considering that the total number of requests usable at any given time across all HW queues is limited by the shared sbitmap depth. As such, it is considerably more memory efficient in the case of shared sbitmap to allocate a set of static rqs per tag set or request queue, and not per HW queue. So replace the sbitmap pairs and active_queues atomic_t with a shared tags per tagset and request queue, which will hold a set of shared static rqs. Since there is now no valid HW queue index to be passed to the blk_mq_ops .init and .exit_request callbacks, pass an invalid index token. This changes the semantics of the APIs, such that the callback would need to validate the HW queue index before using it. Currently no user of shared sbitmap actually uses the HW queue index (as would be expected). Signed-off-by: John Garry <john.garry@huawei.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/1633429419-228500-13-git-send-email-john.garry@huawei.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
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645db34e |
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05-Oct-2021 |
John Garry <john.garry@huawei.com> |
blk-mq: Refactor and rename blk_mq_free_map_and_{requests->rqs}() Refactor blk_mq_free_map_and_requests() such that it can be used at many sites at which the tag map and rqs are freed. Also rename to blk_mq_free_map_and_rqs(), which is shorter and matches the alloc equivalent. Suggested-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: John Garry <john.garry@huawei.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Link: https://lore.kernel.org/r/1633429419-228500-12-git-send-email-john.garry@huawei.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
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63064be1 |
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05-Oct-2021 |
John Garry <john.garry@huawei.com> |
blk-mq: Add blk_mq_alloc_map_and_rqs() Add a function to combine allocating tags and the associated requests, and factor out common patterns to use this new function. Some function only call blk_mq_alloc_map_and_rqs() now, but more functionality will be added later. Also make blk_mq_alloc_rq_map() and blk_mq_alloc_rqs() static since they are only used in blk-mq.c, and finally rename some functions for conciseness and consistency with other function names: - __blk_mq_alloc_map_and_{request -> rqs}() - blk_mq_alloc_{map_and_requests -> set_map_and_rqs}() Suggested-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: John Garry <john.garry@huawei.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/1633429419-228500-11-git-send-email-john.garry@huawei.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
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fd2ef39c |
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23-Jun-2021 |
Jan Kara <jack@suse.cz> |
blk: Fix lock inversion between ioc lock and bfqd lock 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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61347154 |
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02-Jun-2021 |
Jan Kara <jack@suse.cz> |
block: Do not pull requests from the scheduler when we cannot dispatch them Provided the device driver does not implement dispatch budget accounting (which only SCSI does) the loop in __blk_mq_do_dispatch_sched() pulls requests from the IO scheduler as long as it is willing to give out any. That defeats scheduling heuristics inside the scheduler by creating false impression that the device can take more IO when it in fact cannot. For example with BFQ IO scheduler on top of virtio-blk device setting blkio cgroup weight has barely any impact on observed throughput of async IO because __blk_mq_do_dispatch_sched() always sucks out all the IO queued in BFQ. BFQ first submits IO from higher weight cgroups but when that is all dispatched, it will give out IO of lower weight cgroups as well. And then we have to wait for all this IO to be dispatched to the disk (which means lot of it actually has to complete) before the IO scheduler is queried again for dispatching more requests. This completely destroys any service differentiation. So grab request tag for a request pulled out of the IO scheduler already in __blk_mq_do_dispatch_sched() and do not pull any more requests if we cannot get it because we are unlikely to be able to dispatch it. That way only single request is going to wait in the dispatch list for some tag to free. Reviewed-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jan Kara <jack@suse.cz> Link: https://lore.kernel.org/r/20210603104721.6309-1-jack@suse.cz Signed-off-by: Jens Axboe <axboe@kernel.dk>
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2e315dc0 |
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11-May-2021 |
Ming Lei <ming.lei@redhat.com> |
blk-mq: grab rq->refcount before calling ->fn in blk_mq_tagset_busy_iter Grab rq->refcount before calling ->fn in blk_mq_tagset_busy_iter(), and this way will prevent the request from being re-used when ->fn is running. The approach is same as what we do during handling timeout. Fix request use-after-free(UAF) related with completion race or queue releasing: - If one rq is referred before rq->q is frozen, then queue won't be frozen before the request is released during iteration. - If one rq is referred after rq->q is frozen, refcount_inc_not_zero() will return false, and we won't iterate over this request. However, still one request UAF not covered: refcount_inc_not_zero() may read one freed request, and it will be handled in next patch. Tested-by: John Garry <john.garry@huawei.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20210511152236.763464-3-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
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2a5a24aa |
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21-Jan-2021 |
Ming Lei <ming.lei@redhat.com> |
scsi: blk-mq: Return budget token from .get_budget callback SCSI uses a global atomic variable to track queue depth for each LUN/request queue. This doesn't scale well when there are lots of CPU cores and the disk is very fast. It has been observed that IOPS is affected a lot by tracking queue depth via sdev->device_busy in the I/O path. Return budget token from .get_budget callback. The budget token can be passed to driver so that we can replace the atomic variable with sbitmap_queue and alleviate the scaling problems that way. Link: https://lore.kernel.org/r/20210122023317.687987-9-ming.lei@redhat.com Cc: Omar Sandoval <osandov@fb.com> Cc: Kashyap Desai <kashyap.desai@broadcom.com> Cc: Sumanesh Samanta <sumanesh.samanta@broadcom.com> Cc: Ewan D. Milne <emilne@redhat.com> Tested-by: Sumanesh Samanta <sumanesh.samanta@broadcom.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
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2569063c |
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27-Dec-2020 |
Ming Lei <ming.lei@redhat.com> |
blk-mq: test QUEUE_FLAG_HCTX_ACTIVE for sbitmap_shared in hctx_may_queue In case of blk_mq_is_sbitmap_shared(), we should test QUEUE_FLAG_HCTX_ACTIVE against q->queue_flags instead of BLK_MQ_S_TAG_ACTIVE. So fix it. Cc: John Garry <john.garry@huawei.com> Cc: Kashyap Desai <kashyap.desai@broadcom.com> Fixes: f1b49fdc1c64 ("blk-mq: Record active_queues_shared_sbitmap per tag_set for when using shared sbitmap") Signed-off-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: John Garry <john.garry@huawei.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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d220a214 |
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04-Dec-2020 |
Minwoo Im <minwoo.im.dev@gmail.com> |
blk-mq: update arg in comment of blk_mq_map_queue Update mis-named argument description of blk_mq_map_queue(). This patch also updates description that argument to software queue percpu context. Signed-off-by: Minwoo Im <minwoo.im.dev@gmail.com> Reviewed-by: John Garry <john.garry@huawei.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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8446fe92 |
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24-Nov-2020 |
Christoph Hellwig <hch@lst.de> |
block: switch partition lookup to use struct block_device Use struct block_device to lookup partitions on a disk. This removes all usage of struct hd_struct from the I/O path. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Acked-by: Coly Li <colyli@suse.de> [bcache] Acked-by: Chao Yu <yuchao0@huawei.com> [f2fs] Signed-off-by: Jens Axboe <axboe@kernel.dk>
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f1b49fdc |
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19-Aug-2020 |
John Garry <john.garry@huawei.com> |
blk-mq: Record active_queues_shared_sbitmap per tag_set for when using shared sbitmap For when using a shared sbitmap, no longer should the number of active request queues per hctx be relied on for when judging how to share the tag bitmap. Instead maintain the number of active request queues per tag_set, and make the judgement based on that. Originally-from: Kashyap Desai <kashyap.desai@broadcom.com> Signed-off-by: John Garry <john.garry@huawei.com> Tested-by: Don Brace<don.brace@microsemi.com> #SCSI resv cmds patches used Tested-by: Douglas Gilbert <dgilbert@interlog.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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bccf5e26 |
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19-Aug-2020 |
John Garry <john.garry@huawei.com> |
blk-mq: Record nr_active_requests per queue for when using shared sbitmap The per-hctx nr_active value can no longer be used to fairly assign a share of tag depth per request queue for when using a shared sbitmap, as it does not consider that the tags are shared tags over all hctx's. For this case, record the nr_active_requests per request_queue, and make the judgement based on that value. Co-developed-with: Kashyap Desai <kashyap.desai@broadcom.com> Signed-off-by: John Garry <john.garry@huawei.com> Tested-by: Don Brace<don.brace@microsemi.com> #SCSI resv cmds patches used Tested-by: Douglas Gilbert <dgilbert@interlog.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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a0235d23 |
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19-Aug-2020 |
John Garry <john.garry@huawei.com> |
blk-mq: Relocate hctx_may_queue() blk-mq.h and blk-mq-tag.h include on each other, which is less than ideal. Locate hctx_may_queue() to blk-mq.h, as it is not really tag specific code. In this way, we can drop the blk-mq-tag.h include of blk-mq.h Signed-off-by: John Garry <john.garry@huawei.com> Tested-by: Douglas Gilbert <dgilbert@interlog.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
32bc15af |
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19-Aug-2020 |
John Garry <john.garry@huawei.com> |
blk-mq: Facilitate a shared sbitmap per tagset Some SCSI HBAs (such as HPSA, megaraid, mpt3sas, hisi_sas_v3 ..) support multiple reply queues with single hostwide tags. In addition, these drivers want to use interrupt assignment in pci_alloc_irq_vectors(PCI_IRQ_AFFINITY). However, as discussed in [0], CPU hotplug may cause in-flight IO completion to not be serviced when an interrupt is shutdown. That problem is solved in commit bf0beec0607d ("blk-mq: drain I/O when all CPUs in a hctx are offline"). However, to take advantage of that blk-mq feature, the HBA HW queuess are required to be mapped to that of the blk-mq hctx's; to do that, the HBA HW queues need to be exposed to the upper layer. In making that transition, the per-SCSI command request tags are no longer unique per Scsi host - they are just unique per hctx. As such, the HBA LLDD would have to generate this tag internally, which has a certain performance overhead. However another problem is that blk-mq assumes the host may accept (Scsi_host.can_queue * #hw queue) commands. In commit 6eb045e092ef ("scsi: core: avoid host-wide host_busy counter for scsi_mq"), the Scsi host busy counter was removed, which would stop the LLDD being sent more than .can_queue commands; however, it should still be ensured that the block layer does not issue more than .can_queue commands to the Scsi host. To solve this problem, introduce a shared sbitmap per blk_mq_tag_set, which may be requested at init time. New flag BLK_MQ_F_TAG_HCTX_SHARED should be set when requesting the tagset to indicate whether the shared sbitmap should be used. Even when BLK_MQ_F_TAG_HCTX_SHARED is set, a full set of tags and requests are still allocated per hctx; the reason for this is that if tags and requests were only allocated for a single hctx - like hctx0 - it may break block drivers which expect a request be associated with a specific hctx, i.e. not always hctx0. This will introduce extra memory usage. This change is based on work originally from Ming Lei in [1] and from Bart's suggestion in [2]. [0] https://lore.kernel.org/linux-block/alpine.DEB.2.21.1904051331270.1802@nanos.tec.linutronix.de/ [1] https://lore.kernel.org/linux-block/20190531022801.10003-1-ming.lei@redhat.com/ [2] https://lore.kernel.org/linux-block/ff77beff-5fd9-9f05-12b6-826922bace1f@huawei.com/T/#m3db0a602f095cbcbff27e9c884d6b4ae826144be Signed-off-by: John Garry <john.garry@huawei.com> Tested-by: Don Brace<don.brace@microsemi.com> #SCSI resv cmds patches used Tested-by: Douglas Gilbert <dgilbert@interlog.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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1c0706a7 |
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19-Aug-2020 |
John Garry <john.garry@huawei.com> |
blk-mq: Pass flags for tag init/free Pass hctx/tagset flags argument down to blk_mq_init_tags() and blk_mq_free_tags() for selective init/free. For now, make it include the alloc policy flag, which can be evaluated when needed (in blk_mq_init_tags()). Signed-off-by: John Garry <john.garry@huawei.com> Tested-by: Douglas Gilbert <dgilbert@interlog.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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4e2f62e5 |
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01-Jul-2020 |
Jens Axboe <axboe@kernel.dk> |
Revert "blk-mq: put driver tag when this request is completed" 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>
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723bf178 |
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30-Jun-2020 |
Ming Lei <ming.lei@redhat.com> |
blk-mq: move blk_mq_put_driver_tag() into blk-mq.c 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>
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1fd40b5e |
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30-Jun-2020 |
Ming Lei <ming.lei@redhat.com> |
blk-mq: pass obtained budget count to blk_mq_dispatch_rq_list 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>
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445874e8 |
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30-Jun-2020 |
Ming Lei <ming.lei@redhat.com> |
blk-mq: pass hctx to blk_mq_dispatch_rq_list 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>
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65c76369 |
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30-Jun-2020 |
Ming Lei <ming.lei@redhat.com> |
blk-mq: pass request queue into get/put budget callback 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>
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42fdc5e4 |
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29-Jun-2020 |
Christoph Hellwig <hch@lst.de> |
blk-mq: remove the BLK_MQ_REQ_INTERNAL flag 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>
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d94ecfc3 |
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05-Jun-2020 |
Christoph Hellwig <hch@lst.de> |
blk-mq: split out a __blk_mq_get_driver_tag helper Allocation of the driver tag in the case of using a scheduler shares very little code with the "normal" tag allocation. Split out a new helper to streamline this path, and untangle it from the complex normal tag allocation. This way also avoids to fail driver tag allocation because of inactive hctx during cpu hotplug, and fixes potential hang risk. Fixes: bf0beec0607d ("blk-mq: drain I/O when all CPUs in a hctx are offline") Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Tested-by: John Garry <john.garry@huawei.com> Cc: Dongli Zhang <dongli.zhang@oracle.com> Cc: Hannes Reinecke <hare@suse.de> Cc: Daniel Wagner <dwagner@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
76647368 |
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29-May-2020 |
Christoph Hellwig <hch@lst.de> |
blk-mq: use BLK_MQ_NO_TAG in more places Replace various magic -1 constants for tags with BLK_MQ_NO_TAG. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Daniel Wagner <dwagner@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
cae740a0 |
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26-Feb-2020 |
John Garry <john.garry@huawei.com> |
blk-mq: Remove some unused function arguments The struct blk_mq_hw_ctx pointer argument in blk_mq_put_tag(), blk_mq_poll_nsecs(), and blk_mq_poll_hybrid_sleep() is unused, so remove it. Overall obj code size shows a minor reduction, before: text data bss dec hex filename 27306 1312 0 28618 6fca block/blk-mq.o 4303 272 0 4575 11df block/blk-mq-tag.o after: 27282 1312 0 28594 6fb2 block/blk-mq.o 4311 272 0 4583 11e7 block/blk-mq-tag.o Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: John Garry <john.garry@huawei.com> -- This minor patch had been carried as part of the blk-mq shared tags RFC, I'd rather not carry it anymore as it required rebasing, so now or never.. Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
01e99aec |
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24-Feb-2020 |
Ming Lei <ming.lei@redhat.com> |
blk-mq: insert passthrough request into hctx->dispatch directly For some reason, device may be in one situation which can't handle FS request, so STS_RESOURCE is always returned and the FS request will be added to hctx->dispatch. However passthrough request may be required at that time for fixing the problem. If passthrough request is added to scheduler queue, there isn't any chance for blk-mq to dispatch it given we prioritize requests in hctx->dispatch. Then the FS IO request may never be completed, and IO hang is caused. So passthrough request has to be added to hctx->dispatch directly for fixing the IO hang. Fix this issue by inserting passthrough request into hctx->dispatch directly together withing adding FS request to the tail of hctx->dispatch in blk_mq_dispatch_rq_list(). Actually we add FS request to tail of hctx->dispatch at default, see blk_mq_request_bypass_insert(). Then it becomes consistent with original legacy IO request path, in which passthrough request is always added to q->queue_head. Cc: Dongli Zhang <dongli.zhang@oracle.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Ewan D. Milne <emilne@redhat.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
27a46989 |
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30-Sep-2019 |
Pavel Begunkov <asml.silence@gmail.com> |
blk-mq: Inline status checkers blk_mq_request_completed() and blk_mq_request_started() are short, inline it. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
b49773e7 |
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10-Jul-2019 |
Damien Le Moal <damien.lemoal@wdc.com> |
block: Disable write plugging for zoned block devices Simultaneously writing to a sequential zone of a zoned block device from multiple contexts requires mutual exclusion for BIO issuing to ensure that writes happen sequentially. However, even for a well behaved user correctly implementing such synchronization, BIO plugging may interfere and result in BIOs from the different contextx to be reordered if plugging is done outside of the mutual exclusion section, e.g. the plug was started by a function higher in the call chain than the function issuing BIOs. Context A Context B | blk_start_plug() | ... | seq_write_zone() | mutex_lock(zone) | bio-0->bi_iter.bi_sector = zone->wp | zone->wp += bio_sectors(bio-0) | submit_bio(bio-0) | bio-1->bi_iter.bi_sector = zone->wp | zone->wp += bio_sectors(bio-1) | submit_bio(bio-1) | mutex_unlock(zone) | return | -----------------------> | seq_write_zone() | mutex_lock(zone) | bio-2->bi_iter.bi_sector = zone->wp | zone->wp += bio_sectors(bio-2) | submit_bio(bio-2) | mutex_unlock(zone) | <------------------------- | | blk_finish_plug() In the above example, despite the mutex synchronization ensuring the correct BIO issuing order 0, 1, 2, context A BIOs 0 and 1 end up being issued after BIO 2 of context B, when the plug is released with blk_finish_plug(). While this problem can be addressed using the blk_flush_plug_list() function (in the above example, the call must be inserted before the zone mutex lock is released), a simple generic solution in the block layer avoid this additional code in all zoned block device user code. The simple generic solution implemented with this patch is to introduce the internal helper function blk_mq_plug() to access the current context plug on BIO submission. This helper returns the current plug only if the target device is not a zoned block device or if the BIO to be plugged is not a write operation. Otherwise, the caller context plug is ignored and NULL returned, resulting is all writes to zoned block device to never be plugged. Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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c05f4220 |
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01-Jul-2019 |
Bart Van Assche <bvanassche@acm.org> |
blk-mq: remove blk_mq_put_ctx() No code that occurs between blk_mq_get_ctx() and blk_mq_put_ctx() depends on preemption being disabled for its correctness. Since removing the CPU preemption calls does not measurably affect performance, simplify the blk-mq code by removing the blk_mq_put_ctx() function and also by not disabling preemption in blk_mq_get_ctx(). Cc: Hannes Reinecke <hare@suse.com> Cc: Omar Sandoval <osandov@fb.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
c7e2d94b |
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29-Apr-2019 |
Ming Lei <ming.lei@redhat.com> |
blk-mq: free hw queue's resource in hctx's release handler Once blk_cleanup_queue() returns, tags shouldn't be used any more, because blk_mq_free_tag_set() may be called. Commit 45a9c9d909b2 ("blk-mq: Fix a use-after-free") fixes this issue exactly. However, that commit introduces another issue. Before 45a9c9d909b2, we are allowed to run queue during cleaning up queue if the queue's kobj refcount is held. After that commit, queue can't be run during queue cleaning up, otherwise oops can be triggered easily because some fields of hctx are freed by blk_mq_free_queue() in blk_cleanup_queue(). We have invented ways for addressing this kind of issue before, such as: 8dc765d438f1 ("SCSI: fix queue cleanup race before queue initialization is done") c2856ae2f315 ("blk-mq: quiesce queue before freeing queue") But still can't cover all cases, recently James reports another such kind of issue: https://marc.info/?l=linux-scsi&m=155389088124782&w=2 This issue can be quite hard to address by previous way, given scsi_run_queue() may run requeues for other LUNs. Fixes the above issue by freeing hctx's resources in its release handler, and this way is safe becasue tags isn't needed for freeing such hctx resource. This approach follows typical design pattern wrt. kobject's release handler. Cc: Dongli Zhang <dongli.zhang@oracle.com> Cc: James Smart <james.smart@broadcom.com> Cc: Bart Van Assche <bart.vanassche@wdc.com> Cc: linux-scsi@vger.kernel.org, Cc: Martin K . Petersen <martin.petersen@oracle.com>, Cc: Christoph Hellwig <hch@lst.de>, Cc: James E . J . Bottomley <jejb@linux.vnet.ibm.com>, Reported-by: James Smart <james.smart@broadcom.com> Fixes: 45a9c9d909b2 ("blk-mq: Fix a use-after-free") Cc: stable@vger.kernel.org Reviewed-by: Hannes Reinecke <hare@suse.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Tested-by: James Smart <james.smart@broadcom.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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fd9c40f6 |
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04-Apr-2019 |
Bart Van Assche <bvanassche@acm.org> |
block: Revert v5.0 blk_mq_request_issue_directly() changes blk_mq_try_issue_directly() can return BLK_STS*_RESOURCE for requests that have been queued. If that happens when blk_mq_try_issue_directly() is called by the dm-mpath driver then dm-mpath will try to resubmit a request that is already queued and a kernel crash follows. Since it is nontrivial to fix blk_mq_request_issue_directly(), revert the blk_mq_request_issue_directly() changes that went into kernel v5.0. This patch reverts the following commits: * d6a51a97c0b2 ("blk-mq: replace and kill blk_mq_request_issue_directly") # v5.0. * 5b7a6f128aad ("blk-mq: issue directly with bypass 'false' in blk_mq_sched_insert_requests") # v5.0. * 7f556a44e61d ("blk-mq: refactor the code of issue request directly") # v5.0. Cc: Christoph Hellwig <hch@infradead.org> Cc: Ming Lei <ming.lei@redhat.com> Cc: Jianchao Wang <jianchao.w.wang@oracle.com> Cc: Hannes Reinecke <hare@suse.com> Cc: Johannes Thumshirn <jthumshirn@suse.de> Cc: James Smart <james.smart@broadcom.com> Cc: Dongli Zhang <dongli.zhang@oracle.com> Cc: Laurence Oberman <loberman@redhat.com> Cc: <stable@vger.kernel.org> Reported-by: Laurence Oberman <loberman@redhat.com> Tested-by: Laurence Oberman <loberman@redhat.com> Fixes: 7f556a44e61d ("blk-mq: refactor the code of issue request directly") # v5.0. Signed-off-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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13f06381 |
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24-Mar-2019 |
Yufen Yu <yuyufen@huawei.com> |
blk-mq: use blk_mq_put_driver_tag() to put tag Expect arguments, blk_mq_put_driver_tag_hctx() and blk_mq_put_driver_tag() is same. We can just use argument 'request' to put tag by blk_mq_put_driver_tag(). Then we can remove the unused blk_mq_put_driver_tag_hctx(). Signed-off-by: Yufen Yu <yuyufen@huawei.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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e6c98712 |
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20-Mar-2019 |
Bart Van Assche <bvanassche@acm.org> |
block: Unexport blk_mq_add_to_requeue_list() This function is not used outside the block layer core. Hence unexport it. Cc: Christoph Hellwig <hch@lst.de> Cc: Ming Lei <ming.lei@redhat.com> Signed-off-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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26984841 |
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24-Jan-2019 |
Liu Bo <bo.liu@linux.alibaba.com> |
blk-mq: remove duplicated definition of blk_mq_freeze_queue As the prototype has been defined in "include/linux/blk-mq.h", the one in "block/blk-mq.h" can be removed then. Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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bb94aea1 |
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24-Jan-2019 |
Jianchao Wang <jianchao.w.wang@oracle.com> |
blk-mq: save default hctx into ctx->hctxs for not-supported type Currently, we check whether the hctx type is supported every time in hot path. Actually, this is not necessary, we could save the default hctx into ctx->hctxs if the type is not supported when map swqueues and use it directly with ctx->hctxs[type]. We also needn't check whether the poll is enabled or not, because the caller would clear the REQ_HIPRI in that case. Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
8ccdf4a3 |
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24-Jan-2019 |
Jianchao Wang <jianchao.w.wang@oracle.com> |
blk-mq: save queue mapping result into ctx directly Currently, the queue mapping result is saved in a two-dimensional array. In the hot path, to get a hctx, we need do following: q->queue_hw_ctx[q->tag_set->map[type].mq_map[cpu]] This isn't very efficient. We could save the queue mapping result into ctx directly with different hctx type, like, ctx->hctxs[type] Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
c16d6b5a |
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17-Dec-2018 |
Ming Lei <ming.lei@redhat.com> |
blk-mq: fix dispatch from sw queue When a request is added to rq list of sw queue(ctx), the rq may be from a different type of hctx, especially after multi queue mapping is introduced. So when dispach request from sw queue via blk_mq_flush_busy_ctxs() or blk_mq_dequeue_from_ctx(), one request belonging to other queue type of hctx can be dispatched to current hctx in case that read queue or poll queue is enabled. This patch fixes this issue by introducing per-queue-type list. Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Ming Lei <ming.lei@redhat.com> Changed by me to not use separately cacheline aligned lists, just place them all in the same cacheline where we had just the one list and lock before. Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
5aceaeb2 |
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16-Dec-2018 |
Christoph Hellwig <hch@lst.de> |
blk-mq: only dispatch to non-defauly queue maps if they have queues We should check if a given queue map actually has queues enabled before dispatching to it. This allows drivers to not initialize optional but not used map types, which subsequently will allow fixing problems with queue map rebuilds for that case. Reviewed-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
d6a51a97 |
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13-Dec-2018 |
Jianchao Wang <jianchao.w.wang@oracle.com> |
blk-mq: replace and kill blk_mq_request_issue_directly Replace blk_mq_request_issue_directly with blk_mq_try_issue_directly in blk_insert_cloned_request and kill it as nobody uses it any more. Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
e016b782 |
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06-Dec-2018 |
Mikulas Patocka <mpatocka@redhat.com> |
block: return just one value from part_in_flight The previous patches deleted all the code that needed the second value returned from part_in_flight - now the kernel only uses the first value. Consequently, part_in_flight (and blk_mq_in_flight) may be changed so that it only returns one value. This patch just refactors the code, there's no functional change. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
e20ba6e1 |
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02-Dec-2018 |
Christoph Hellwig <hch@lst.de> |
block: move queues types to the block layer Having another indirect all in the fast path doesn't really help in our post-spectre world. Also having too many queue type is just going to create confusion, so I'd rather manage them centrally. Note that the queue type naming and ordering changes a bit - the first index now is the default queue for everything not explicitly marked, the optional ones are read and poll queues. Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
be94f058 |
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24-Nov-2018 |
Jens Axboe <axboe@kernel.dk> |
blk-mq: use bd->last == true for list inserts If we are issuing a list of requests, we know if we're at the last one. If we fail issuing, ensure that we call ->commits_rqs() to flush any potential previous requests. Reviewed-by: Omar Sandoval <osandov@fb.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
1db4909e |
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19-Nov-2018 |
Ming Lei <ming.lei@redhat.com> |
blk-mq: not embed .mq_kobj and ctx->kobj into queue instance Even though .mq_kobj, ctx->kobj and q->kobj share same lifetime from block layer's view, actually they don't because userspace may grab one kobject anytime via sysfs. This patch fixes the issue by the following approach: 1) introduce 'struct blk_mq_ctxs' for holding .mq_kobj and managing all ctxs 2) free all allocated ctxs and the 'blk_mq_ctxs' instance in release handler of .mq_kobj 3) grab one ref of .mq_kobj before initializing each ctx->kobj, so that .mq_kobj is always released after all ctxs are freed. This patch fixes kernel panic issue during booting when DEBUG_KOBJECT_RELEASE is enabled. Reported-by: Guenter Roeck <linux@roeck-us.net> Cc: "jianchao.wang" <jianchao.w.wang@oracle.com> Tested-by: Guenter Roeck <linux@roeck-us.net> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
ea4f995e |
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29-Oct-2018 |
Jens Axboe <axboe@kernel.dk> |
blk-mq: cache request hardware queue mapping 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>
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#
b3c661b1 |
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30-Oct-2018 |
Jens Axboe <axboe@kernel.dk> |
blk-mq: support multiple hctx maps Add support for the tag set carrying multiple queue maps, and for the driver to inform blk-mq how many it wishes to support through setting set->nr_maps. This adds an mq_ops helper for drivers that support more than 1 map, mq_ops->rq_flags_to_type(). The function takes request/bio flags and CPU, and returns a queue map index for that. We then use the type information in blk_mq_map_queue() to index the map set. Reviewed-by: Hannes Reinecke <hare@suse.com> Reviewed-by: Keith Busch <keith.busch@intel.com> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
f31967f0 |
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29-Oct-2018 |
Jens Axboe <axboe@kernel.dk> |
blk-mq: allow software queue to map to multiple hardware queues The mapping used to be dependent on just the CPU location, but now it's a tuple of (type, cpu) instead. This is a prep patch for allowing a single software queue to map to multiple hardware queues. No functional changes in this patch. This changes the software queue count to an unsigned short to save a bit of space. We can still support 64K-1 CPUs, which should be enough. Add a check to catch a wrap. Reviewed-by: Hannes Reinecke <hare@suse.com> Reviewed-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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f9afca4d |
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29-Oct-2018 |
Jens Axboe <axboe@kernel.dk> |
blk-mq: pass in request/bio flags to queue mapping 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>
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#
ff2c5660 |
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29-Oct-2018 |
Jens Axboe <axboe@kernel.dk> |
blk-mq: provide dummy blk_mq_map_queue_type() helper Doesn't do anything right now, but it's needed as a prep patch to get the interfaces right. While in there, correct the blk_mq_map_queue() CPU type to an unsigned int. Reviewed-by: Hannes Reinecke <hare@suse.com> Reviewed-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
ed76e329 |
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29-Oct-2018 |
Jens Axboe <axboe@kernel.dk> |
blk-mq: abstract out queue map This is in preparation for allowing multiple sets of maps per queue, if so desired. Reviewed-by: Hannes Reinecke <hare@suse.com> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
a8908939 |
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16-Oct-2018 |
Jens Axboe <axboe@kernel.dk> |
blk-mq: kill q->mq_map It's just a pointer to set->mq_map, use that instead. Move the assignment a bit earlier, so we always know it's valid. Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.com> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
6ce3dd6e |
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09-Jul-2018 |
Ming Lei <ming.lei@redhat.com> |
blk-mq: issue directly if hw queue isn't busy in case of 'none' In case of 'none' io scheduler, when hw queue isn't busy, it isn't necessary to enqueue request to sw queue and dequeue it from sw queue because request may be submitted to hw queue asap without extra cost, meantime there shouldn't be much request in sw queue, and we don't need to worry about effect on IO merge. There are still some single hw queue SCSI HBAs(HPSA, megaraid_sas, ...) which may connect high performance devices, so 'none' is often required for obtaining good performance. This patch improves IOPS and decreases CPU unilization on megaraid_sas, per Kashyap's test. Cc: Kashyap Desai <kashyap.desai@broadcom.com> Cc: Laurence Oberman <loberman@redhat.com> Cc: Omar Sandoval <osandov@fb.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Bart Van Assche <bart.vanassche@wdc.com> Cc: Hannes Reinecke <hare@suse.de> Reported-by: Kashyap Desai <kashyap.desai@broadcom.com> Tested-by: Kashyap Desai <kashyap.desai@broadcom.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
0da73d00 |
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02-Jul-2018 |
Minwoo Im <minwoo.im.dev@gmail.com> |
blk-mq: code clean-up by adding an API to clear set->mq_map set->mq_map is now currently cleared if something goes wrong when establishing a queue map in blk-mq-pci.c. It's also cleared before updating a queue map in blk_mq_update_queue_map(). This patch provides an API to clear set->mq_map to make it clear. Signed-off-by: Minwoo Im <minwoo.im.dev@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
8ab6bb9e |
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25-Jun-2018 |
Ming Lei <ming.lei@redhat.com> |
blk-mq: cleanup blk_mq_get_driver_tag() We never pass 'wait' as true to blk_mq_get_driver_tag(), and hence we never change '**hctx' as well. The last use of these went away with the flush cleanup, commit 0c2a6fe4dc3e. So cleanup the usage and remove the two extra parameters. Cc: Bart Van Assche <bart.vanassche@wdc.com> Cc: Christoph Hellwig <hch@lst.de> Tested-by: Andrew Jones <drjones@redhat.com> Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
12f5b931 |
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29-May-2018 |
Keith Busch <kbusch@kernel.org> |
blk-mq: Remove generation seqeunce This patch simplifies the timeout handling by relying on the request reference counting to ensure the iterator is operating on an inflight and truly timed out request. Since the reference counting prevents the tag from being reallocated, the block layer no longer needs to prevent drivers from completing their requests while the timeout handler is operating on it: a driver completing a request is allowed to proceed to the next state without additional syncronization with the block layer. This also removes any need for generation sequence numbers since the request lifetime is prevented from being reallocated as a new sequence while timeout handling is operating on it. To enables this a refcount is added to struct request so that request users can be sure they're operating on the same request without it changing while they're processing it. The request's tag won't be released for reuse until both the timeout handler and the completion are done with it. Signed-off-by: Keith Busch <keith.busch@intel.com> [hch: slight cleanups, added back submission side hctx lock, use cmpxchg for completions] Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
bf0ddaba |
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26-Apr-2018 |
Omar Sandoval <osandov@fb.com> |
blk-mq: fix sysfs inflight counter When the blk-mq inflight implementation was added, /proc/diskstats was converted to use it, but /sys/block/$dev/inflight was not. Fix it by adding another helper to count in-flight requests by data direction. Fixes: f299b7c7a9de ("blk-mq: provide internal in-flight variant") Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
fe644072 |
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20-Apr-2018 |
Linus Walleij <linus.walleij@linaro.org> |
block: mq: Add some minor doc for core structs As it came up in discussion on the mailing list that the semantic meaning of 'blk_mq_ctx' and 'blk_mq_hw_ctx' isn't completely obvious to everyone, let's add some minimal kerneldoc for a starter. Signed-off-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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2434af79 |
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11-Apr-2018 |
Ming Lei <ming.lei@redhat.com> |
blk-mq: Revert "blk-mq: reimplement blk_mq_hw_queue_mapped" This reverts commit 127276c6ce5a30fcc806b7fe53015f4f89b62956. When all CPUs of one hw queue become offline, there still may have IOs not completed from this hctx. But blk_mq_hw_queue_mapped() is called in blk_mq_queue_tag_busy_iter(), which is used for iterating request in timeout handler, timeout event will be missed on the inactive hctx, then request may never be completed. Also the replementation of blk_mq_hw_queue_mapped() doesn't match the helper's name any more, and it should have been named as blk_mq_hw_queue_active(). Even other callers need further verification about this reimplemenation. So revert this patch now, and we can improve hw queue activate/inactivate event after adequent researching and test. Cc: Stefan Haberland <sth@linux.vnet.ibm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christoph Hellwig <hch@lst.de> Reported-by: Jens Axboe <axboe@kernel.dk> Fixes: 127276c6ce5a30fcc ("blk-mq: reimplement blk_mq_hw_queue_mapped") Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
127276c6 |
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08-Apr-2018 |
Ming Lei <ming.lei@redhat.com> |
blk-mq: reimplement blk_mq_hw_queue_mapped Now the actual meaning of queue mapped is that if there is any online CPU mapped to this hctx, so implement blk_mq_hw_queue_mapped() in this way. Cc: Stefan Haberland <sth@linux.vnet.ibm.com> Tested-by: Christian Borntraeger <borntraeger@de.ibm.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
c77ff7fd |
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19-Jan-2018 |
Bart Van Assche <bvanassche@acm.org> |
blk-mq: Rename blk_mq_request_direct_issue() into blk_mq_request_issue_directly() Most blk-mq functions have a name that follows the pattern blk_mq_${action}. However, the function name blk_mq_request_direct_issue is an exception. Hence rename this function. This patch does not change any functionality. Reviewed-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
396eaf21 |
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17-Jan-2018 |
Ming Lei <ming.lei@redhat.com> |
blk-mq: improve DM's blk-mq IO merging via blk_insert_cloned_request feedback blk_insert_cloned_request() is called in the fast path of a dm-rq driver (e.g. blk-mq request-based DM mpath). blk_insert_cloned_request() uses blk_mq_request_bypass_insert() to directly append the request to the blk-mq hctx->dispatch_list of the underlying queue. 1) This way isn't efficient enough because the hctx spinlock is always used. 2) With blk_insert_cloned_request(), we completely bypass underlying queue's elevator and depend on the upper-level dm-rq driver's elevator to schedule IO. But dm-rq currently can't get the underlying queue's dispatch feedback at all. Without knowing whether a request was issued or not (e.g. due to underlying queue being busy) the dm-rq elevator will not be able to provide effective IO merging (as a side-effect of dm-rq currently blindly destaging a request from its elevator only to requeue it after a delay, which kills any opportunity for merging). This obviously causes very bad sequential IO performance. Fix this by updating blk_insert_cloned_request() to use blk_mq_request_direct_issue(). blk_mq_request_direct_issue() allows a request to be issued directly to the underlying queue and returns the dispatch feedback (blk_status_t). If blk_mq_request_direct_issue() returns BLK_SYS_RESOURCE the dm-rq driver will now use DM_MAPIO_REQUEUE to _not_ destage the request. Whereby preserving the opportunity to merge IO. With this, request-based DM's blk-mq sequential IO performance is vastly improved (as much as 3X in mpath/virtio-scsi testing). Signed-off-by: Ming Lei <ming.lei@redhat.com> [blk-mq.c changes heavily influenced by Ming Lei's initial solution, but they were refactored to make them less fragile and easier to read/review] Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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5a61c363 |
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09-Jan-2018 |
Tejun Heo <tj@kernel.org> |
blk-mq: remove REQ_ATOM_STARTED After the recent updates to use generation number and state based synchronization, we can easily replace REQ_ATOM_STARTED usages by adding an extra state to distinguish completed but not yet freed state. Add MQ_RQ_COMPLETE and replace REQ_ATOM_STARTED usages with blk_mq_rq_state() tests. REQ_ATOM_STARTED no longer has any users left and is removed. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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358f70da |
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09-Jan-2018 |
Tejun Heo <tj@kernel.org> |
blk-mq: make blk_abort_request() trigger timeout path With issue/complete and timeout paths now using the generation number and state based synchronization, blk_abort_request() is the only one which depends on REQ_ATOM_COMPLETE for arbitrating completion. There's no reason for blk_abort_request() to be a completely separate path. This patch makes blk_abort_request() piggyback on the timeout path instead of trying to terminate the request directly. This removes the last dependency on REQ_ATOM_COMPLETE in blk-mq. Note that this makes blk_abort_request() asynchronous - it initiates abortion but the actual termination will happen after a short while, even when the caller owns the request. AFAICS, SCSI and ATA should be fine with that and I think mtip32xx and dasd should be safe but not completely sure. It'd be great if people who know the drivers take a look. v2: - Add comment explaining the lack of synchronization around ->deadline update as requested by Bart. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Asai Thambi SP <asamymuthupa@micron.com> Cc: Stefan Haberland <sth@linux.vnet.ibm.com> Cc: Jan Hoeppner <hoeppner@linux.vnet.ibm.com> Cc: Bart Van Assche <Bart.VanAssche@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
1d9bd516 |
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09-Jan-2018 |
Tejun Heo <tj@kernel.org> |
blk-mq: replace timeout synchronization with a RCU and generation based scheme Currently, blk-mq timeout path synchronizes against the usual issue/completion path using a complex scheme involving atomic bitflags, REQ_ATOM_*, memory barriers and subtle memory coherence rules. Unfortunately, it contains quite a few holes. There's a complex dancing around REQ_ATOM_STARTED and REQ_ATOM_COMPLETE between issue/completion and timeout paths; however, they don't have a synchronization point across request recycle instances and it isn't clear what the barriers add. blk_mq_check_expired() can easily read STARTED from N-2'th iteration, deadline from N-1'th, blk_mark_rq_complete() against Nth instance. In fact, it's pretty easy to make blk_mq_check_expired() terminate a later instance of a request. If we induce 5 sec delay before time_after_eq() test in blk_mq_check_expired(), shorten the timeout to 2s, and issue back-to-back large IOs, blk-mq starts timing out requests spuriously pretty quickly. Nothing actually timed out. It just made the call on a recycle instance of a request and then terminated a later instance long after the original instance finished. The scenario isn't theoretical either. This patch replaces the broken synchronization mechanism with a RCU and generation number based one. 1. Each request has a u64 generation + state value, which can be updated only by the request owner. Whenever a request becomes in-flight, the generation number gets bumped up too. This provides the basis for the timeout path to distinguish different recycle instances of the request. Also, marking a request in-flight and setting its deadline are protected with a seqcount so that the timeout path can fetch both values coherently. 2. The timeout path fetches the generation, state and deadline. If the verdict is timeout, it records the generation into a dedicated request abortion field and does RCU wait. 3. The completion path is also protected by RCU (from the previous patch) and checks whether the current generation number and state match the abortion field. If so, it skips completion. 4. The timeout path, after RCU wait, scans requests again and terminates the ones whose generation and state still match the ones requested for abortion. By now, the timeout path knows that either the generation number and state changed if it lost the race or the completion will yield to it and can safely timeout the request. While it's more lines of code, it's conceptually simpler, doesn't depend on direct use of subtle memory ordering or coherence, and hopefully doesn't terminate the wrong instance. While this change makes REQ_ATOM_COMPLETE synchronization unnecessary between issue/complete and timeout paths, REQ_ATOM_COMPLETE isn't removed yet as it's still used in other places. Future patches will move all state tracking to the new mechanism and remove all bitops in the hot paths. Note that this patch adds a comment explaining a race condition in BLK_EH_RESET_TIMER path. The race has always been there and this patch doesn't change it. It's just documenting the existing race. v2: - Fixed BLK_EH_RESET_TIMER handling as pointed out by Jianchao. - s/request->gstate_seqc/request->gstate_seq/ as suggested by Peter. - READ_ONCE() added in blk_mq_rq_update_state() as suggested by Peter. v3: - Fixed possible extended seqcount / u64_stats_sync read looping spotted by Peter. - MQ_RQ_IDLE was incorrectly being set in complete_request instead of free_request. Fixed. v4: - Rebased on top of hctx_lock() refactoring patch. - Added comment explaining the use of hctx_lock() in completion path. v5: - Added comments requested by Bart. - Note the addition of BLK_EH_RESET_TIMER race condition in the commit message. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: "jianchao.wang" <jianchao.w.wang@oracle.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Bart Van Assche <Bart.VanAssche@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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79f720a7 |
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10-Nov-2017 |
Jens Axboe <axboe@kernel.dk> |
blk-mq: only run the hardware queue if IO is pending Currently we are inconsistent in when we decide to run the queue. Using blk_mq_run_hw_queues() we check if the hctx has pending IO before running it, but we don't do that from the individual queue run function, blk_mq_run_hw_queue(). This results in a lot of extra and pointless queue runs, potentially, on flush requests and (much worse) on tag starvation situations. This is observable just looking at top output, with lots of kworkers active. For the !async runs, it just adds to the CPU overhead of blk-mq. Move the has-pending check into the run function instead of having callers do it. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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9a95e4ef |
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09-Nov-2017 |
Bart Van Assche <bvanassche@acm.org> |
block, nvme: Introduce blk_mq_req_flags_t Several block layer and NVMe core functions accept a combination of BLK_MQ_REQ_* flags through the 'flags' argument but there is no verification at compile time whether the right type of block layer flags is passed. Make it possible for sparse to verify this. This patch does not change any functionality. Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com> Reviewed-by: Hannes Reinecke <hare@suse.com> Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name> Cc: linux-nvme@lists.infradead.org Cc: Christoph Hellwig <hch@lst.de> Cc: Johannes Thumshirn <jthumshirn@suse.de> Cc: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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244c65a3 |
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04-Nov-2017 |
Ming Lei <ming.lei@redhat.com> |
blk-mq: move blk_mq_put_driver_tag*() into blk-mq.h We need this helper to put the driver tag for flush rq, since we will not share tag in the flush request sequence in the following patch in case that I/O scheduler is applied. Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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b0850297 |
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02-Nov-2017 |
Ming Lei <ming.lei@redhat.com> |
block: pass 'run_queue' to blk_mq_request_bypass_insert Block flush need this function without running the queue, so add a parameter controlling whether we run it or not. Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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88022d72 |
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04-Nov-2017 |
Ming Lei <ming.lei@redhat.com> |
blk-mq: don't handle failure in .get_budget It is enough to just check if we can get the budget via .get_budget(). And we don't need to deal with device state change in .get_budget(). For SCSI, one issue to be fixed is that we have to call scsi_mq_uninit_cmd() to free allocated ressources if SCSI device fails to handle the request. And it isn't enough to simply call blk_mq_end_request() to do that if this request is marked as RQF_DONTPREP. Fixes: 0df21c86bdbf(scsi: implement .get_budget and .put_budget for blk-mq) Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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b2441318 |
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01-Nov-2017 |
Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
License cleanup: add SPDX GPL-2.0 license identifier to files with no license Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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#
b347689f |
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14-Oct-2017 |
Ming Lei <ming.lei@redhat.com> |
blk-mq-sched: improve dispatching from sw queue SCSI devices use host-wide tagset, and the shared driver tag space is often quite big. However, there is also a queue depth for each lun( .cmd_per_lun), which is often small, for example, on both lpfc and qla2xxx, .cmd_per_lun is just 3. So lots of requests may stay in sw queue, and we always flush all belonging to same hw queue and dispatch them all to driver. Unfortunately it is easy to cause queue busy because of the small .cmd_per_lun. Once these requests are flushed out, they have to stay in hctx->dispatch, and no bio merge can happen on these requests, and sequential IO performance is harmed. This patch introduces blk_mq_dequeue_from_ctx for dequeuing a request from a sw queue, so that we can dispatch them in scheduler's way. We can then avoid dequeueing too many requests from sw queue, since we don't flush ->dispatch completely. This patch improves dispatching from sw queue by using the .get_budget and .put_budget callbacks. Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
de148297 |
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14-Oct-2017 |
Ming Lei <ming.lei@redhat.com> |
blk-mq: introduce .get_budget and .put_budget in blk_mq_ops For SCSI devices, there is often a per-request-queue depth, which needs to be respected before queuing one request. Currently blk-mq always dequeues the request first, then calls .queue_rq() to dispatch the request to lld. One obvious issue with this approach is that I/O merging may not be successful, because when the per-request-queue depth can't be respected, .queue_rq() has to return BLK_STS_RESOURCE, and then this request has to stay in hctx->dispatch list. This means it never gets a chance to be merged with other IO. This patch introduces .get_budget and .put_budget callback in blk_mq_ops, then we can try to get reserved budget first before dequeuing request. If the budget for queueing I/O can't be satisfied, we don't need to dequeue request at all. Hence the request can be left in the IO scheduler queue, for more merging opportunities. Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
157f377b |
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11-Sep-2017 |
Jens Axboe <axboe@kernel.dk> |
block: directly insert blk-mq request from blk_insert_cloned_request() A NULL pointer crash was reported for the case of having the BFQ IO scheduler attached to the underlying blk-mq paths of a DM multipath device. The crash occured in blk_mq_sched_insert_request()'s call to e->type->ops.mq.insert_requests(). Paolo Valente correctly summarized why the crash occured with: "the call chain (dm_mq_queue_rq -> map_request -> setup_clone -> blk_rq_prep_clone) creates a cloned request without invoking e->type->ops.mq.prepare_request for the target elevator e. The cloned request is therefore not initialized for the scheduler, but it is however inserted into the scheduler by blk_mq_sched_insert_request." All said, a request-based DM multipath device's IO scheduler should be the only one used -- when the original requests are issued to the underlying paths as cloned requests they are inserted directly in the underlying dispatch queue(s) rather than through an additional elevator. But commit bd166ef18 ("blk-mq-sched: add framework for MQ capable IO schedulers") switched blk_insert_cloned_request() from using blk_mq_insert_request() to blk_mq_sched_insert_request(). Which incorrectly added elevator machinery into a call chain that isn't supposed to have any. To fix this introduce a blk-mq private blk_mq_request_bypass_insert() that blk_insert_cloned_request() calls to insert the request without involving any elevator that may be attached to the cloned request's request_queue. Fixes: bd166ef183c2 ("blk-mq-sched: add framework for MQ capable IO schedulers") Cc: stable@vger.kernel.org Reported-by: Bart Van Assche <Bart.VanAssche@wdc.com> Tested-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
f299b7c7 |
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08-Aug-2017 |
Jens Axboe <axboe@kernel.dk> |
blk-mq: provide internal in-flight variant We don't have to inc/dec some counter, since we can just iterate the tags. That makes inc/dec a noop, but means we have to iterate busy tags to get an in-flight count. Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com> Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
4b855ad3 |
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25-Jun-2017 |
Christoph Hellwig <hch@lst.de> |
blk-mq: Create hctx for each present CPU Currently we only create hctx for online CPUs, which can lead to a lot of churn due to frequent soft offline / online operations. Instead allocate one for each present CPU to avoid this and dramatically simplify the code. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jens Axboe <axboe@kernel.dk> Cc: Keith Busch <keith.busch@intel.com> Cc: linux-block@vger.kernel.org Cc: linux-nvme@lists.infradead.org Link: http://lkml.kernel.org/r/20170626102058.10200-3-hch@lst.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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#
e4cdf1a1 |
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16-Jun-2017 |
Christoph Hellwig <hch@lst.de> |
blk-mq: remove __blk_mq_alloc_request Move most code into blk_mq_rq_ctx_init, and the rest into blk_mq_get_request. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
6af54051 |
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16-Jun-2017 |
Christoph Hellwig <hch@lst.de> |
blk-mq: simplify blk_mq_free_request Merge three functions only tail-called by blk_mq_free_request into blk_mq_free_request. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
6e15cf2a |
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16-Jun-2017 |
Christoph Hellwig <hch@lst.de> |
blk-mq: mark blk_mq_rq_ctx_init static Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
d173a251 |
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04-May-2017 |
Omar Sandoval <osandov@fb.com> |
blk-mq: move debugfs declarations to a separate header file Preparation for adding more declarations. Signed-off-by: Omar Sandoval <osandov@fb.com> Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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#
62d6c949 |
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26-Apr-2017 |
Bart Van Assche <bvanassche@acm.org> |
blk-mq-debugfs: Rename functions for registering and unregistering the mq directory Since the blk_mq_debugfs_*register_hctxs() functions register and unregister all attributes under the "mq" directory, rename these into blk_mq_debugfs_*register_mq(). Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com> Reviewed-by: Hannes Reinecke <hare@suse.com> Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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#
4c9e4019 |
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26-Apr-2017 |
Bart Van Assche <bvanassche@acm.org> |
blk-mq: Let blk_mq_debugfs_register() look up the queue name A later patch will move the call of blk_mq_debugfs_register() to a function to which the queue name is not passed as an argument. To avoid having to add a 'name' argument to multiple callers, let blk_mq_debugfs_register() look up the queue name. Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com> Reviewed-by: Omar Sandoval <osandov@fb.com> Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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#
2d0364c8 |
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26-Apr-2017 |
Bart Van Assche <bvanassche@acm.org> |
blk-mq: Register <dev>/queue/mq after having registered <dev>/queue A later patch in this series will modify blk_mq_debugfs_register() such that it uses q->kobj.parent to determine the name of a request queue. Hence make sure that that pointer is initialized before blk_mq_debugfs_register() is called. To avoid lock inversion, protect sysfs / debugfs registration with the queue sysfs_lock instead of the global mutex all_q_mutex. Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com> Reviewed-by: Hannes Reinecke <hare@suse.com> Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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#
229a9287 |
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14-Apr-2017 |
Omar Sandoval <osandov@fb.com> |
blk-mq: add shallow depth option for blk_mq_get_tag() 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>
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#
81380ca1 |
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07-Apr-2017 |
Omar Sandoval <osandov@fb.com> |
blk-mq: use the right hctx when getting a driver tag fails While dispatching requests, if we fail to get a driver tag, we mark the hardware queue as waiting for a tag and put the requests on a hctx->dispatch list to be run later when a driver tag is freed. However, blk_mq_dispatch_rq_list() may dispatch requests from multiple hardware queues if using a single-queue scheduler with a multiqueue device. If blk_mq_get_driver_tag() fails, it doesn't update the hardware queue we are processing. This means we end up using the hardware queue of the previous request, which may or may not be the same as that of the current request. If it isn't, the wrong hardware queue will end up waiting for a tag, and the requests will be on the wrong dispatch list, leading to a hang. The fix is twofold: 1. Make sure we save which hardware queue we were trying to get a request for in blk_mq_get_driver_tag() regardless of whether it succeeds or not. 2. Make blk_mq_dispatch_rq_list() take a request_queue instead of a blk_mq_hw_queue to make it clear that it must handle multiple hardware queues, since I've already messed this up on a couple of occasions. This didn't appear in testing with nvme and mq-deadline because nvme has more driver tags than the default number of scheduler tags. However, with the blk_mq_update_nr_hw_queues() fix, it showed up with nbd. Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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#
34dbad5d |
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21-Mar-2017 |
Omar Sandoval <osandov@fb.com> |
blk-stat: convert to callback-based statistics reporting Currently, statistics are gathered in ~0.13s windows, and users grab the statistics whenever they need them. This is not ideal for both in-tree users: 1. Writeback throttling wants its own dynamically sized window of statistics. Since the blk-stats statistics are reset after every window and the wbt windows don't line up with the blk-stats windows, wbt doesn't see every I/O. 2. Polling currently grabs the statistics on every I/O. Again, depending on how the window lines up, we may miss some I/Os. It's also unnecessary overhead to get the statistics on every I/O; the hybrid polling heuristic would be just as happy with the statistics from the previous full window. This reworks the blk-stats infrastructure to be callback-based: users register a callback that they want called at a given time with all of the statistics from the window during which the callback was active. Users can dynamically bucketize the statistics. wbt and polling both currently use read vs. write, but polling can be extended to further subdivide based on request size. The callbacks are kept on an RCU list, and each callback has percpu stats buffers. There will only be a few users, so the overhead on the I/O completion side is low. The stats flushing is also simplified considerably: since the timer function is responsible for clearing the statistics, we don't have to worry about stale statistics. wbt is a trivial conversion. After the conversion, the windowing problem mentioned above is fixed. For polling, we register an extra callback that caches the previous window's statistics in the struct request_queue for the hybrid polling heuristic to use. Since we no longer have a single stats buffer for the request queue, this also removes the sysfs and debugfs stats entries. To replace those, we add a debugfs entry for the poll statistics. Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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#
7ea5fe31 |
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22-Feb-2017 |
Ming Lei <tom.leiming@gmail.com> |
blk-mq: make lifetime consitent between q/ctx and its kobject Currently from kobject view, both q->mq_kobj and ctx->kobj can be released during one cycle of blk_mq_register_dev() and blk_mq_unregister_dev(). Actually, sw queue's lifetime is same with its request queue's, which is covered by request_queue->kobj. So we don't need to call kobject_put() for the two kinds of kobject in __blk_mq_unregister_dev(), instead we do that in release handler of request queue. Signed-off-by: Ming Lei <tom.leiming@gmail.com> Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Jens Axboe <axboe@fb.com>
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#
737f98cf |
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22-Feb-2017 |
Ming Lei <tom.leiming@gmail.com> |
blk-mq: initialize mq kobjects in blk_mq_init_allocated_queue() Both q->mq_kobj and sw queues' kobjects should have been initialized once, instead of doing that each add_disk context. Also this patch removes clearing of ctx in blk_mq_init_cpu_queues() because percpu allocator fills zero to allocated variable. This patch fixes one issue[1] reported from Omar. [1] kernel wearning when doing unbind/bind on one scsi-mq device [ 19.347924] kobject (ffff8800791ea0b8): tried to init an initialized object, something is seriously wrong. [ 19.349781] CPU: 1 PID: 84 Comm: kworker/u8:1 Not tainted 4.10.0-rc7-00210-g53f39eeaa263 #34 [ 19.350686] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.1-20161122_114906-anatol 04/01/2014 [ 19.350920] Workqueue: events_unbound async_run_entry_fn [ 19.350920] Call Trace: [ 19.350920] dump_stack+0x63/0x83 [ 19.350920] kobject_init+0x77/0x90 [ 19.350920] blk_mq_register_dev+0x40/0x130 [ 19.350920] blk_register_queue+0xb6/0x190 [ 19.350920] device_add_disk+0x1ec/0x4b0 [ 19.350920] sd_probe_async+0x10d/0x1c0 [sd_mod] [ 19.350920] async_run_entry_fn+0x48/0x150 [ 19.350920] process_one_work+0x1d0/0x480 [ 19.350920] worker_thread+0x48/0x4e0 [ 19.350920] kthread+0x101/0x140 [ 19.350920] ? process_one_work+0x480/0x480 [ 19.350920] ? kthread_create_on_node+0x60/0x60 [ 19.350920] ret_from_fork+0x2c/0x40 Cc: Omar Sandoval <osandov@osandov.com> Signed-off-by: Ming Lei <tom.leiming@gmail.com> Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Jens Axboe <axboe@fb.com>
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#
59748398 |
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27-Feb-2017 |
Omar Sandoval <osandov@fb.com> |
blk-mq: kill blk_mq_set_alloc_data() Nothing is using it anymore. Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com> Tested-by: Sagi Grimberg <sagi@grimberg.me>
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#
18fbda91 |
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31-Jan-2017 |
Omar Sandoval <osandov@fb.com> |
block: use same block debugfs directory for blk-mq and blktrace When I added the blk-mq debugging information to debugfs, I didn't notice that blktrace also creates a "block" directory in debugfs. Make them use the same dentry, now created in the core block code. Based on a patch from Jens. Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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#
400f73b2 |
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27-Jan-2017 |
Omar Sandoval <osandov@fb.com> |
blk-mq: fix debugfs compilation issues This fixes a couple of problems: 1. In the !CONFIG_DEBUG_FS case, the stub definitions were bogus. 2. In the !CONFIG_BLOCK case, blk-mq-debugfs.c shouldn't be compiled at all. Fix the stub definitions and add a CONFIG_BLK_DEBUG_FS Kconfig option. Fixes: 07e4fead45e6 ("blk-mq: create debugfs directory tree") Signed-off-by: Omar Sandoval <osandov@fb.com> Augment Kconfig description. Signed-off-by: Jens Axboe <axboe@fb.com>
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#
bd6737f1 |
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27-Jan-2017 |
Jens Axboe <axboe@fb.com> |
blk-mq-sched: add flush insertion into blk_mq_sched_insert_request() 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>
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#
50e1dab8 |
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26-Jan-2017 |
Jens Axboe <axboe@fb.com> |
blk-mq-sched: fix starvation for multiple hardware queues and shared tags If we have both multiple hardware queues and shared tag map between devices, we need to ensure that we propagate the hardware queue restart bit higher up. This is because we can get into a situation where we don't have any IO pending on a hardware queue, yet we fail getting a tag to start new IO. If that happens, it's not enough to mark the hardware queue as needing a restart, we need to bubble that up to the higher level queue as well. Signed-off-by: Jens Axboe <axboe@fb.com> Reviewed-by: Omar Sandoval <osandov@fb.com> Tested-by: Hannes Reinecke <hare@suse.com>
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#
07e4fead |
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25-Jan-2017 |
Omar Sandoval <osandov@fb.com> |
blk-mq: create debugfs directory tree In preparation for putting blk-mq debugging information in debugfs, create a directory tree mirroring the one in sysfs: # tree -d /sys/kernel/debug/block /sys/kernel/debug/block |-- nvme0n1 | `-- mq | |-- 0 | | `-- cpu0 | |-- 1 | | `-- cpu1 | |-- 2 | | `-- cpu2 | `-- 3 | `-- cpu3 `-- vda `-- mq `-- 0 |-- cpu0 |-- cpu1 |-- cpu2 `-- cpu3 Also add the scaffolding for the actual files that will go in here, either under the hardware queue or software queue directories. Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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#
bd166ef1 |
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17-Jan-2017 |
Jens Axboe <axboe@fb.com> |
blk-mq-sched: add framework for MQ capable IO schedulers This adds a set of hooks that intercepts the blk-mq path of allocating/inserting/issuing/completing requests, allowing us to develop a scheduler within that framework. We reuse the existing elevator scheduler API on the registration side, but augment that with the scheduler flagging support for the blk-mq interfce, and with a separate set of ops hooks for MQ devices. We split driver and scheduler tags, so we can run the scheduling independently of device queue depth. Signed-off-by: Jens Axboe <axboe@fb.com> Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com> Reviewed-by: Omar Sandoval <osandov@fb.com>
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#
cc71a6f4 |
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11-Jan-2017 |
Jens Axboe <axboe@fb.com> |
blk-mq: abstract out helpers for allocating/freeing tag maps Prep patch for adding an extra tag map for scheduler requests. Signed-off-by: Jens Axboe <axboe@fb.com> Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com> Reviewed-by: Omar Sandoval <osandov@fb.com>
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#
4941115b |
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13-Jan-2017 |
Jens Axboe <axboe@fb.com> |
blk-mq-tag: cleanup the normal/reserved tag allocation 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>
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#
2c3ad667 |
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14-Dec-2016 |
Jens Axboe <axboe@fb.com> |
blk-mq: export some helpers we need to the scheduling framework Signed-off-by: Jens Axboe <axboe@fb.com> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by: Omar Sandoval <osandov@fb.com>
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#
f04c3df3 |
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07-Dec-2016 |
Jens Axboe <axboe@fb.com> |
blk-mq: abstract out blk_mq_dispatch_rq_list() helper Takes a list of requests, and dispatches it. Moves any residual requests to the dispatch list. Signed-off-by: Jens Axboe <axboe@fb.com> Reviewed-by: Hannes Reinecke <hare@suse.com>
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#
cf43e6be |
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07-Nov-2016 |
Jens Axboe <axboe@fb.com> |
block: add scalable completion tracking of requests For legacy block, we simply track them in the request queue. For blk-mq, we track them on a per-sw queue basis, which we can then sum up through the hardware queues and finally to a per device state. The stats are tracked in, roughly, 0.1s interval windows. Add sysfs files to display the stats. The feature is off by default, to avoid any extra overhead. In-kernel users of it can turn it on by setting QUEUE_FLAG_STATS in the queue flags. We currently don't turn it on if someone just reads any of the stats files, that is something we could add as well. Signed-off-by: Jens Axboe <axboe@fb.com>
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#
9e5a7e22 |
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01-Nov-2016 |
Christoph Hellwig <hch@lst.de> |
blk-mq: export blk_mq_map_queues This will allow SCSI to have a single blk_mq_ops structure that either lets the LLDD map the queues to PCIe MSIx vectors or use the default. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.com> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Reviewed-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
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#
5d1b25c1 |
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28-Oct-2016 |
Bart Van Assche <bvanassche@acm.org> |
blk-mq: Introduce blk_mq_hctx_stopped() Multiple functions test the BLK_MQ_S_STOPPED bit so introduce a helper function that performs this test. Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com> Reviewed-by: Ming Lei <tom.leiming@gmail.com> Reviewed-by: Hannes Reinecke <hare@suse.com> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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#
9467f859 |
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22-Sep-2016 |
Thomas Gleixner <tglx@linutronix.de> |
blk-mq/cpu-notif: Convert to new hotplug state machine Replace the block-mq notifier list management with the multi instance facility in the cpu hotplug state machine. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: linux-block@vger.kernel.org Cc: rt@linutronix.de Cc: Christoph Hellwing <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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#
40aabb67 |
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17-Sep-2016 |
Omar Sandoval <osandov@fb.com> |
sbitmap: push per-cpu last_tag into sbitmap_queue 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>
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#
88459642 |
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17-Sep-2016 |
Omar Sandoval <osandov@fb.com> |
blk-mq: abstract tag allocation out into sbitmap library 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>
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da695ba2 |
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14-Sep-2016 |
Christoph Hellwig <hch@lst.de> |
blk-mq: allow the driver to pass in a queue mapping This allows drivers specify their own queue mapping by overriding the setup-time function that builds the mq_map. This can be used for example to build the map based on the MSI-X vector mapping provided by the core interrupt layer for PCI devices. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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7d7e0f90 |
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14-Sep-2016 |
Christoph Hellwig <hch@lst.de> |
blk-mq: remove ->map_queue 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>
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#
868f2f0b |
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17-Dec-2015 |
Keith Busch <kbusch@kernel.org> |
blk-mq: dynamic h/w context count The hardware's provided queue count may change at runtime with resource provisioning. This patch allows a block driver to alter the number of h/w queues available when its resource count changes. The main part is a new blk-mq API to request a new number of h/w queues for a given live tag set. The new API freezes all queues using that set, then adjusts the allocated count prior to remapping these to CPUs. The bulk of the rest just shifts where h/w contexts and all their artifacts are allocated and freed. The number of max h/w contexts is capped to the number of possible cpus since there is no use for more than that. As such, all pre-allocated memory for pointers need to account for the max possible rather than the initial number of queues. A side effect of this is that the blk-mq will proceed successfully as long as it can allocate at least one h/w context. Previously it would fail request queue initialization if less than the requested number was allocated. Signed-off-by: Keith Busch <keith.busch@intel.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Tested-by: Jon Derrick <jonathan.derrick@intel.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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#
6f3b0e8b |
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26-Nov-2015 |
Christoph Hellwig <hch@lst.de> |
blk-mq: add a flags parameter to blk_mq_alloc_request 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>
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1fa8cc52 |
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05-Nov-2015 |
Jens Axboe <axboe@fb.com> |
blk-mq: mark __blk_mq_complete_request() static It's no longer used outside of blk-mq core. Signed-off-by: Jens Axboe <axboe@fb.com>
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#
3380f458 |
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09-Oct-2015 |
Christoph Hellwig <hch@lst.de> |
blk-mq: remove unused blk_mq_clone_flush_request prototype Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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#
5778322e |
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26-Sep-2015 |
Akinobu Mita <akinobu.mita@gmail.com> |
blk-mq: avoid inserting requests before establishing new mapping Notifier callbacks for CPU_ONLINE action can be run on the other CPU than the CPU which was just onlined. So it is possible for the process running on the just onlined CPU to insert request and run hw queue before establishing new mapping which is done by blk_mq_queue_reinit_notify(). This can cause a problem when the CPU has just been onlined first time since the request queue was initialized. At this time ctx->index_hw for the CPU, which is the index in hctx->ctxs[] for this ctx, is still zero before blk_mq_queue_reinit_notify() is called by notifier callbacks for CPU_ONLINE action. For example, there is a single hw queue (hctx) and two CPU queues (ctx0 for CPU0, and ctx1 for CPU1). Now CPU1 is just onlined and a request is inserted into ctx1->rq_list and set bit0 in pending bitmap as ctx1->index_hw is still zero. And then while running hw queue, flush_busy_ctxs() finds bit0 is set in pending bitmap and tries to retrieve requests in hctx->ctxs[0]->rq_list. But htx->ctxs[0] is a pointer to ctx0, so the request in ctx1->rq_list is ignored. Fix it by ensuring that new mapping is established before onlined cpu starts running. Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Reviewed-by: Ming Lei <tom.leiming@gmail.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Ming Lei <tom.leiming@gmail.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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#
e09aae7e |
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29-Jan-2015 |
Ming Lei <ming.lei@canonical.com> |
blk-mq: release mq's kobjects in blk_release_queue() The kobject memory inside blk-mq hctx/ctx shouldn't have been freed before the kobject is released because driver core can access it freely before its release. We can't do that in all ctx/hctx/mq_kobj's release handler because it can be run before blk_cleanup_queue(). Given mq_kobj shouldn't have been introduced, this patch simply moves mq's release into blk_release_queue(). Reported-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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#
aed3ea94 |
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22-Dec-2014 |
Jens Axboe <axboe@fb.com> |
block: wake up waiters when a queue is marked dying If it's dying, we can't expect new request to complete and come in an wake up other tasks waiting for requests. So after we have marked it as dying, wake up everybody currently waiting for a request. Once they wake, they will retry their allocation and fail appropriately due to the state of the queue. Tested-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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#
19c66e59 |
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03-Dec-2014 |
Ming Lei <ming.lei@canonical.com> |
blk-mq: prevent unmapped hw queue from being scheduled When one hardware queue has no mapped software queues, it shouldn't have been scheduled. Otherwise WARNING or OOPS can triggered. blk_mq_hw_queue_mapped() helper is introduce for fixing the problem. Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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#
f3552655 |
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25-Sep-2014 |
Ming Lei <ming.lei@canonical.com> |
block: introduce blk_init_flush and its pair These two temporary functions are introduced for holding flush initialization and de-initialization, so that we can introduce 'flush queue' easier in the following patch. And once 'flush queue' and its allocation/free functions are ready, they will be removed for sake of code readability. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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#
1bcb1ead |
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25-Sep-2014 |
Ming Lei <ming.lei@canonical.com> |
blk-mq: allocate flush_rq in blk_mq_init_flush() It is reasonable to allocate flush req in blk_mq_init_flush(). Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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#
90415837 |
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22-Sep-2014 |
Christoph Hellwig <hch@lst.de> |
block: fix blk_abort_request on blk-mq Signed-off-by: Christoph Hellwig <hch@lst.de> Moved blk_mq_rq_timed_out() definition to the private blk-mq.h header. Signed-off-by: Jens Axboe <axboe@fb.com>
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#
780db207 |
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01-Jul-2014 |
Tejun Heo <tj@kernel.org> |
blk-mq: decouble blk-mq freezing from generic bypassing blk_mq freezing is entangled with generic bypassing which bypasses blkcg and io scheduler and lets IO requests fall through the block layer to the drivers in FIFO order. This allows forward progress on IOs with the advanced features disabled so that those features can be configured or altered without worrying about stalling IO which may lead to deadlock through memory allocation. However, generic bypassing doesn't quite fit blk-mq. blk-mq currently doesn't make use of blkcg or ioscheds and it maps bypssing to freezing, which blocks request processing and drains all the in-flight ones. This causes problems as bypassing assumes that request processing is online. blk-mq works around this by conditionally allowing request processing for the problem case - during queue initialization. Another weirdity is that except for during queue cleanup, bypassing started on the generic side prevents blk-mq from processing new requests but doesn't drain the in-flight ones. This shouldn't break anything but again highlights that something isn't quite right here. The root cause is conflating blk-mq freezing and generic bypassing which are two different mechanisms. The only intersecting purpose that they serve is during queue cleanup. Let's properly separate blk-mq freezing from generic bypassing and simply use it where necessary. * request_queue->mq_freeze_depth is added and blk_mq_[un]freeze_queue() now operate on this counter instead of ->bypass_depth. The replacement for QUEUE_FLAG_BYPASS isn't added but the counter is tested directly. This will be further updated by later changes. * blk_mq_drain_queue() is dropped and "__" prefix is dropped from blk_mq_freeze_queue(). Queue cleanup path now calls blk_mq_freeze_queue() directly. * blk_queue_enter()'s fast path condition is simplified to simply check @q->mq_freeze_depth. Previously, the condition was !blk_queue_dying(q) && (!blk_queue_bypass(q) || !blk_queue_init_done(q)) mq_freeze_depth is incremented right after dying is set and blk_queue_init_done() exception isn't necessary as blk-mq doesn't start frozen, which only leaves the blk_queue_bypass() test which can be replaced by @q->mq_freeze_depth test. This change simplifies the code and reduces confusion in the area. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Nicholas A. Bellinger <nab@linux-iscsi.org> Signed-off-by: Jens Axboe <axboe@fb.com>
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#
cb96a42c |
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31-May-2014 |
Ming Lei <tom.leiming@gmail.com> |
blk-mq: fix schedule from atomic context blk_mq_put_ctx() has to be called before io_schedule() in bt_get(). This patch fixes the problem by taking similar approach from percpu_ida allocation for the situation. Signed-off-by: Ming Lei <tom.leiming@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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#
1aecfe48 |
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31-May-2014 |
Ming Lei <tom.leiming@gmail.com> |
blk-mq: move blk_mq_get_ctx/blk_mq_put_ctx to mq private header The blk-mq tag code need these helpers. Signed-off-by: Ming Lei <tom.leiming@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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#
67aec14c |
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30-May-2014 |
Jens Axboe <axboe@fb.com> |
blk-mq: make the sysfs mq/ layout reflect current mappings Currently blk-mq registers all the hardware queues in sysfs, regardless of whether it uses them (e.g. they have CPU mappings) or not. The unused hardware queues lack the cpux/ directories, and the other sysfs entries (like active, pending, etc) are all zeroes. Change this so that sysfs correctly reflects the current mappings of the hardware queues. Signed-off-by: Jens Axboe <axboe@fb.com>
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#
f14bbe77 |
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27-May-2014 |
Jens Axboe <axboe@fb.com> |
blk-mq: pass in suggested NUMA node to ->alloc_hctx() Drivers currently have to figure this out on their own, and they are missing information to do it properly. The ones that did attempt to do it, do it wrong. So just pass in the suggested node directly to the alloc function. Signed-off-by: Jens Axboe <axboe@fb.com>
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#
e814e71b |
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21-May-2014 |
Jens Axboe <axboe@fb.com> |
blk-mq: allow the hctx cpu hotplug notifier to return errors Prepare this for the next patch which adds more smarts in the plugging logic, so that we can save some memory. Signed-off-by: Jens Axboe <axboe@fb.com>
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#
e3a2b3f9 |
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20-May-2014 |
Jens Axboe <axboe@fb.com> |
blk-mq: allow changing of queue depth through sysfs For request_fn based devices, the block layer exports a 'nr_requests' file through sysfs to allow adjusting of queue depth on the fly. Currently this returns -EINVAL for blk-mq, since it's not wired up. Wire this up for blk-mq, so that it now also always dynamic adjustments of the allowed queue depth for any given block device managed by blk-mq. Signed-off-by: Jens Axboe <axboe@fb.com>
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#
e93ecf60 |
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19-May-2014 |
Jens Axboe <axboe@fb.com> |
blk-mq: move the cache friendly bitmap type of out blk-mq-tag We will use it for the pending list in blk-mq core as well. Signed-off-by: Jens Axboe <axboe@fb.com>
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#
4bb659b1 |
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09-May-2014 |
Jens Axboe <axboe@fb.com> |
blk-mq: implement new and more efficient tagging scheme blk-mq currently uses percpu_ida for tag allocation. But that only works well if the ratio between tag space and number of CPUs is sufficiently high. For most devices and systems, that is not the case. The end result if that we either only utilize the tag space partially, or we end up attempting to fully exhaust it and run into lots of lock contention with stealing between CPUs. This is not optimal. This new tagging scheme is a hybrid bitmap allocator. It uses two tricks to both be SMP friendly and allow full exhaustion of the space: 1) We cache the last allocated (or freed) tag on a per blk-mq software context basis. This allows us to limit the space we have to search. The key element here is not caching it in the shared tag structure, otherwise we end up dirtying more shared cache lines on each allocate/free operation. 2) The tag space is split into cache line sized groups, and each context will start off randomly in that space. Even up to full utilization of the space, this divides the tag users efficiently into cache line groups, avoiding dirtying the same one both between allocators and between allocator and freeer. This scheme shows drastically better behaviour, both on small tag spaces but on large ones as well. It has been tested extensively to show better performance for all the cases blk-mq cares about. Signed-off-by: Jens Axboe <axboe@fb.com>
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#
38535201 |
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25-Apr-2014 |
Christoph Hellwig <hch@lst.de> |
blk-mq: respect rq_affinity The blk-mq code is using it's own version of the I/O completion affinity tunables, which causes a few issues: - the rq_affinity sysfs file doesn't work for blk-mq devices, even if it still is present, thus breaking existing tuning setups. - the rq_affinity = 1 mode, which is the defauly for legacy request based drivers isn't implemented at all. - blk-mq drivers don't implement any completion affinity with the default flag settings. This patches removes the blk-mq ipi_redirect flag and sysfs file, as well as the internal BLK_MQ_F_SHOULD_IPI flag and replaces it with code that respects the queue-wide rq_affinity flags and also implements the rq_affinity = 1 mode. This means I/O completion affinity can now only be tuned block-queue wide instead of per context, which seems more sensible to me anyway. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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87ee7b11 |
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24-Apr-2014 |
Jens Axboe <axboe@fb.com> |
blk-mq: fix race with timeouts and requeue events If a requeue event races with a timeout, we can get into the situation where we attempt to complete a request from the timeout handler when it's not start anymore. This causes a crash. So have the timeout handler check that REQ_ATOM_STARTED is still set on the request - if not, we ignore the event. If this happens, the request has now been marked as complete. As a consequence, we need to ensure to clear REQ_ATOM_COMPLETE in blk_mq_start_request(), as to maintain proper request state. Signed-off-by: Jens Axboe <axboe@fb.com>
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24d2f903 |
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15-Apr-2014 |
Christoph Hellwig <hch@lst.de> |
blk-mq: split out tag initialization, support shared tags Add a new blk_mq_tag_set structure that gets set up before we initialize the queue. A single blk_mq_tag_set structure can be shared by multiple queues. Signed-off-by: Christoph Hellwig <hch@lst.de> Modular export of blk_mq_{alloc,free}_tagset added by me. Signed-off-by: Jens Axboe <axboe@fb.com>
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8727af4b |
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14-Apr-2014 |
Christoph Hellwig <hch@lst.de> |
blk-mq: make ->flush_rq fully transparent to drivers Drivers shouldn't have to care about the block layer setting aside a request to implement the flush state machine. We already override the mq context and tag to make it more transparent, but so far haven't deal with the driver private data in the request. Make sure to override this as well, and while we're at it add a proper helper sitting in blk-mq.c that implements the full impersonation. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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9d74e257 |
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14-Apr-2014 |
Christoph Hellwig <hch@lst.de> |
blk-mq: do not initialize req->special Drivers can reach their private data easily using the blk_mq_rq_to_pdu helper and don't need req->special. By not initializing it code can be simplified nicely, and we also shave off a few more instructions from the I/O path. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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eeabc850 |
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21-Mar-2014 |
Christoph Hellwig <hch@infradead.org> |
blk-mq: merge blk_mq_insert_request and blk_mq_run_request It's almost identical to blk_mq_insert_request, so fold the two into one slightly more generic function by making the flush special case a bit smarted. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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676141e4 |
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20-Mar-2014 |
Jens Axboe <axboe@fb.com> |
blk-mq: don't dump CPU -> hw queue map on driver load Now that we are out of initial debug/bringup mode, remove the verbose dump of the mapping table. Provide the mapping table in sysfs, under the hardware queue directory, in the cpu_list file. Signed-off-by: Jens Axboe <axboe@fb.com>
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feb71dae |
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20-Feb-2014 |
Christoph Hellwig <hch@infradead.org> |
blk-mq: merge blk_mq_insert_request and blk_mq_run_request It's almost identical to blk_mq_insert_request, so fold the two into one slightly more generic function by making the flush special case a bit smarted. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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18741986 |
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10-Feb-2014 |
Christoph Hellwig <hch@lst.de> |
blk-mq: rework flush sequencing logic Witch to using a preallocated flush_rq for blk-mq similar to what's done with the old request path. This allows us to set up the request properly with a tag from the actually allowed range and ->rq_disk as needed by some drivers. To make life easier we also switch to dynamic allocation of ->flush_rq for the old path. This effectively reverts most of "blk-mq: fix for flush deadlock" and "blk-mq: Don't reserve a tag for flush request" Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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30a91cb4 |
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10-Feb-2014 |
Christoph Hellwig <hch@infradead.org> |
blk-mq: rework I/O completions Rework I/O completions to work more like the old code path. blk_mq_end_io now stays out of the business of deferring completions to others CPUs and calling blk_mark_rq_complete. The latter is very important to allow completing requests that have timed out and thus are already marked completed, the former allows using the IPI callout even for driver specific completions instead of having to reimplement them. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
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3d6efbf6 |
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08-Jan-2014 |
Christoph Hellwig <hch@infradead.org> |
blk-mq: use __smp_call_function_single directly __smp_call_function_single already avoids multiple IPIs by internally queing up the items, and now also is available for non-SMP builds as a trivially correct stub, so there is no need to wrap it. If the additional lock roundtrip cause problems my patch to convert the generic IPI code to llists is waiting to get merged will fix it. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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3edcc0ce |
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26-Dec-2013 |
Ming Lei <tom.leiming@gmail.com> |
block: blk-mq: don't export blk_mq_free_queue() blk_mq_free_queue() is called from release handler of queue kobject, so it needn't be called from drivers. Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Ming Lei <tom.leiming@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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43a5e4e2 |
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26-Dec-2013 |
Ming Lei <tom.leiming@gmail.com> |
block: blk-mq: support draining mq queue blk_mq_drain_queue() is introduced so that we can drain mq queue inside blk_cleanup_queue(). Also don't accept new requests any more if queue is marked as dying. Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Ming Lei <tom.leiming@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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320ae51f |
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24-Oct-2013 |
Jens Axboe <axboe@kernel.dk> |
blk-mq: new multi-queue block IO queueing mechanism Linux currently has two models for block devices: - The classic request_fn based approach, where drivers use struct request units for IO. The block layer provides various helper functionalities to let drivers share code, things like tag management, timeout handling, queueing, etc. - The "stacked" approach, where a driver squeezes in between the block layer and IO submitter. Since this bypasses the IO stack, driver generally have to manage everything themselves. With drivers being written for new high IOPS devices, the classic request_fn based driver doesn't work well enough. The design dates back to when both SMP and high IOPS was rare. It has problems with scaling to bigger machines, and runs into scaling issues even on smaller machines when you have IOPS in the hundreds of thousands per device. The stacked approach is then most often selected as the model for the driver. But this means that everybody has to re-invent everything, and along with that we get all the problems again that the shared approach solved. This commit introduces blk-mq, block multi queue support. The design is centered around per-cpu queues for queueing IO, which then funnel down into x number of hardware submission queues. We might have a 1:1 mapping between the two, or it might be an N:M mapping. That all depends on what the hardware supports. blk-mq provides various helper functions, which include: - Scalable support for request tagging. Most devices need to be able to uniquely identify a request both in the driver and to the hardware. The tagging uses per-cpu caches for freed tags, to enable cache hot reuse. - Timeout handling without tracking request on a per-device basis. Basically the driver should be able to get a notification, if a request happens to fail. - Optional support for non 1:1 mappings between issue and submission queues. blk-mq can redirect IO completions to the desired location. - Support for per-request payloads. Drivers almost always need to associate a request structure with some driver private command structure. Drivers can tell blk-mq this at init time, and then any request handed to the driver will have the required size of memory associated with it. - Support for merging of IO, and plugging. The stacked model gets neither of these. Even for high IOPS devices, merging sequential IO reduces per-command overhead and thus increases bandwidth. For now, this is provided as a potential 3rd queueing model, with the hope being that, as it matures, it can replace both the classic and stacked model. That would get us back to having just 1 real model for block devices, leaving the stacked approach to dm/md devices (as it was originally intended). Contributions in this patch from the following people: Shaohua Li <shli@fusionio.com> Alexander Gordeev <agordeev@redhat.com> Christoph Hellwig <hch@infradead.org> Mike Christie <michaelc@cs.wisc.edu> Matias Bjorling <m@bjorling.me> Jeff Moyer <jmoyer@redhat.com> Acked-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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