From 131d08e122eaabae028378c0b4da688eb044c6af Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Thu, 31 May 2018 19:11:40 +0200 Subject: block: split the blk-mq case from elevator_init There is almost no shared logic, which leads to a very confusing code flow. Signed-off-by: Christoph Hellwig Reviewed-by: Damien Le Moal Tested-by: Damien Le Moal Signed-off-by: Jens Axboe --- block/elevator.c | 77 +++++++++++++++++++++++++++++++++----------------------- 1 file changed, 46 insertions(+), 31 deletions(-) (limited to 'block/elevator.c') diff --git a/block/elevator.c b/block/elevator.c index d6480e70816ea..fa828b5bfd4b1 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -199,6 +199,11 @@ static void elevator_release(struct kobject *kobj) kfree(e); } +/* + * Use the default elevator specified by config boot param for non-mq devices, + * or by config option. Don't try to load modules as we could be running off + * async and request_module() isn't allowed from async. + */ int elevator_init(struct request_queue *q) { struct elevator_type *e = NULL; @@ -212,46 +217,22 @@ int elevator_init(struct request_queue *q) if (unlikely(q->elevator)) goto out_unlock; - /* - * Use the default elevator specified by config boot param for - * non-mq devices, or by config option. Don't try to load modules - * as we could be running off async and request_module() isn't - * allowed from async. - */ - if (!q->mq_ops && *chosen_elevator) { + if (*chosen_elevator) { e = elevator_get(q, chosen_elevator, false); if (!e) printk(KERN_ERR "I/O scheduler %s not found\n", chosen_elevator); } + if (!e) + e = elevator_get(q, CONFIG_DEFAULT_IOSCHED, false); if (!e) { - /* - * For blk-mq devices, we default to using mq-deadline, - * if available, for single queue devices. If deadline - * isn't available OR we have multiple queues, default - * to "none". - */ - if (q->mq_ops) { - if (q->nr_hw_queues == 1) - e = elevator_get(q, "mq-deadline", false); - if (!e) - goto out_unlock; - } else - e = elevator_get(q, CONFIG_DEFAULT_IOSCHED, false); - - if (!e) { - printk(KERN_ERR - "Default I/O scheduler not found. " \ - "Using noop.\n"); - e = elevator_get(q, "noop", false); - } + printk(KERN_ERR + "Default I/O scheduler not found. Using noop.\n"); + e = elevator_get(q, "noop", false); } - if (e->uses_mq) - err = blk_mq_init_sched(q, e); - else - err = e->ops.sq.elevator_init_fn(q, e); + err = e->ops.sq.elevator_init_fn(q, e); if (err) elevator_put(e); out_unlock: @@ -992,6 +973,40 @@ out: return ret; } +/* + * For blk-mq devices, we default to using mq-deadline, if available, for single + * queue devices. If deadline isn't available OR we have multiple queues, + * default to "none". + */ +int elevator_init_mq(struct request_queue *q) +{ + struct elevator_type *e; + int err = 0; + + if (q->nr_hw_queues != 1) + return 0; + + /* + * q->sysfs_lock must be held to provide mutual exclusion between + * elevator_switch() and here. + */ + mutex_lock(&q->sysfs_lock); + if (unlikely(q->elevator)) + goto out_unlock; + + e = elevator_get(q, "mq-deadline", false); + if (!e) + goto out_unlock; + + err = blk_mq_init_sched(q, e); + if (err) + elevator_put(e); +out_unlock: + mutex_unlock(&q->sysfs_lock); + return err; +} + + /* * switch to new_e io scheduler. be careful not to introduce deadlocks - * we don't free the old io scheduler, before we have allocated what we -- cgit v1.2.3