blk-mq: Replace tags->lock with SRCU for tag iterators

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Replace the spinlock in blk_mq_find_and_get_req() with an SRCU read lock
around the tag iterators.

This is done by:

- Holding the SRCU read lock in blk_mq_queue_tag_busy_iter(),
blk_mq_tagset_busy_iter(), and blk_mq_hctx_has_requests().

- Removing the now-redundant tags->lock from blk_mq_find_and_get_req().

This change fixes lockup issue in scsi_host_busy() in case of shost->host_blocked.

Also avoids big tags->lock when reading disk sysfs attribute `inflight`.

Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

...

This commit is contained in:

Ming Lei 2025-08-30 10:18:23 +08:00 • committed by Jens Axboe

parent 135b8521f2

commit 995412e23b

2 changed files with 12 additions and 24 deletions

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12

block/blk-mq-tag.c

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24

block/blk-mq.c

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