Damien Le Moal 5234dd5d20 block: mq-deadline: Fix dd_finish_request() for zoned devices
commit 2820e5d0820ac4daedff1272616a53d9c7682fd2 upstream.

dd_finish_request() tests if the per prio fifo_list is not empty to
determine if request dispatching must be restarted for handling blocked
write requests to zoned devices with a call to
blk_mq_sched_mark_restart_hctx(). While simple, this implementation has
2 problems:

1) Only the priority level of the completed request is considered.
   However, writes to a zone may be blocked due to other writes to the
   same zone using a different priority level. While this is unlikely to
   happen in practice, as writing a zone with different IO priorirites
   does not make sense, nothing in the code prevents this from
   happening.
2) The use of list_empty() is dangerous as dd_finish_request() does not
   take dd->lock and may run concurrently with the insert and dispatch
   code.

Fix these 2 problems by testing the write fifo list of all priority
levels using the new helper dd_has_write_work(), and by testing each
fifo list using list_empty_careful().

Fixes: c807ab520fc3 ("block/mq-deadline: Add I/O priority support")
Cc: <stable@vger.kernel.org>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20221124021208.242541-2-damien.lemoal@opensource.wdc.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-01-12 11:59:03 +01:00
..
2021-06-17 15:51:20 +02:00
2020-03-17 20:55:21 +01:00
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