4.18-stable review patch. If anyone has any objections, please let me know.
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From: Damien Le Moal damien.lemoal@wdc.com
commit 854f31ccdd7964c9c2e68da234a3a8aedb51cf6b upstream.
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: 8dc8146f9c92 ("deadline-iosched: Introduce zone locking support") Cc: stable@vger.kernel.org Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- block/elevator.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/block/elevator.c +++ b/block/elevator.c @@ -609,7 +609,7 @@ void elv_drain_elevator(struct request_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);