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authorDamien Le Moal <damien.lemoal@wdc.com>2019-09-05 18:51:31 +0900
committerJens Axboe <axboe@kernel.dk>2019-09-05 19:52:33 -0600
commit68c43f133a754c7bf5cb1018bb16dc0821cc43a1 (patch)
tree79d8eba4264de5d90e3f8bedd2329e5802c94b6e /block/mq-deadline.c
parent954b4a5ce4a806e7c284ce6b2659abdd03d0b6e2 (diff)
block: Introduce elevator features
Introduce the definition of elevator features through the elevator_features flags in the elevator_type structure. Each flag can represent a feature supported by an elevator. The first feature defined by this patch is support for zoned block device sequential write constraint with the flag ELEVATOR_F_ZBD_SEQ_WRITE, which is implemented by the mq-deadline elevator using zone write locking. Other possible features are IO priorities, write hints, latency targets or single-LUN dual-actuator disks (for which the elevator could maintain one LBA ordered list per actuator). The required_elevator_features field is also added to the request_queue structure to allow a device driver to specify elevator feature flags that an elevator must support for the correct operation of the device (e.g. device drivers for zoned block devices can have the ELEVATOR_F_ZBD_SEQ_WRITE flag as a required feature). The helper function blk_queue_required_elevator_features() is defined for setting this new field. With these two new fields in place, the elevator functions elevator_match() and elevator_find() are modified to allow a user to set only an elevator with a set of features that satisfies the device required features. Elevators not matching the device requirements are not shown in the device sysfs queue/scheduler file to prevent their use. The "none" elevator can always be selected as before. Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/mq-deadline.c')
-rw-r--r--block/mq-deadline.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/block/mq-deadline.c b/block/mq-deadline.c
index 35e84bc0ec8c..b490f47fd553 100644
--- a/block/mq-deadline.c
+++ b/block/mq-deadline.c
@@ -794,6 +794,7 @@ static struct elevator_type mq_deadline = {
.elevator_attrs = deadline_attrs,
.elevator_name = "mq-deadline",
.elevator_alias = "deadline",
+ .elevator_features = ELEVATOR_F_ZBD_SEQ_WRITE,
.elevator_owner = THIS_MODULE,
};
MODULE_ALIAS("mq-deadline-iosched");