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authorChristoph Hellwig <hch@lst.de>2018-05-31 19:11:40 +0200
committerJens Axboe <axboe@kernel.dk>2018-06-01 07:38:21 -0600
commit131d08e122eaabae028378c0b4da688eb044c6af (patch)
tree1c48c6886d4e90d543fe738ba4c426531dcd637b /block/elevator.c
parentacddf3b308f6b6e23653de02e1abf98f402f1f12 (diff)
downloadlinux-0-day-131d08e122eaabae028378c0b4da688eb044c6af.tar.gz
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 <hch@lst.de> Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com> Tested-by: Damien Le Moal <damien.lemoal@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/elevator.c')
-rw-r--r--block/elevator.c77
1 files changed, 46 insertions, 31 deletions
diff --git a/block/elevator.c b/block/elevator.c
index d6480e7..fa828b5 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:
@@ -993,6 +974,40 @@ out:
}
/*
+ * 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
* need for the new one. this way we have a chance of going back to the old