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block: fix deadline elevator drain for zoned block devices

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When the deadline scheduler is used with a zoned block device, writes
to a zone will be dispatched one at a time. This causes the warning
message:

deadline: forced dispatching is broken (nr_sorted=X), please report this

to be displayed when switching to another elevator with the legacy I/O
path while write requests to a zone are being retained in the scheduler
queue.

Prevent this message from being displayed when executing
elv_drain_elevator() for a zoned block device. __blk_drain_queue() will
loop until all writes are dispatched and completed, resulting in the
desired elevator queue drain without extensive modifications to the
deadline code itself to handle forced-dispatch calls.

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Fixes: 8dc8146f9c ("deadline-iosched: Introduce zone locking support")
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Damien Le Moal 2018-09-27 10:55:13 +09:00 committed by Jens Axboe
parent 530ca2c9bd
commit 854f31ccdd
1 changed files with 1 additions and 1 deletions
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block/elevator.c
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@ -609,7 +609,7 @@ void elv_drain_elevator(struct request_queue *q)
while (e->type->ops.sq.elevator_dispatch_fn(q, 1))
;
if (q->nr_sorted && printed++ < 10) {
if (q->nr_sorted && !blk_queue_is_zoned(q) && printed++ < 10 ) {
printk(KERN_ERR "%s: forced dispatching is broken "
"(nr_sorted=%u), please report this\n",
q->elevator->type->elevator_name, q->nr_sorted);