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-rw-r--r--block/elevator.c121
1 files changed, 48 insertions, 73 deletions
diff --git a/block/elevator.c b/block/elevator.c
index f016855a46b0..6a55d418896f 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -38,6 +38,7 @@
#include <trace/events/block.h>
#include "blk.h"
+#include "blk-cgroup.h"
static DEFINE_SPINLOCK(elv_list_lock);
static LIST_HEAD(elv_list);
@@ -121,15 +122,6 @@ static struct elevator_type *elevator_get(const char *name)
return e;
}
-static int elevator_init_queue(struct request_queue *q,
- struct elevator_queue *eq)
-{
- eq->elevator_data = eq->type->ops.elevator_init_fn(q);
- if (eq->elevator_data)
- return 0;
- return -ENOMEM;
-}
-
static char chosen_elevator[ELV_NAME_MAX];
static int __init elevator_setup(char *str)
@@ -188,7 +180,6 @@ static void elevator_release(struct kobject *kobj)
int elevator_init(struct request_queue *q, char *name)
{
struct elevator_type *e = NULL;
- struct elevator_queue *eq;
int err;
if (unlikely(q->elevator))
@@ -222,17 +213,16 @@ int elevator_init(struct request_queue *q, char *name)
}
}
- eq = elevator_alloc(q, e);
- if (!eq)
+ q->elevator = elevator_alloc(q, e);
+ if (!q->elevator)
return -ENOMEM;
- err = elevator_init_queue(q, eq);
+ err = e->ops.elevator_init_fn(q);
if (err) {
- kobject_put(&eq->kobj);
+ kobject_put(&q->elevator->kobj);
return err;
}
- q->elevator = eq;
return 0;
}
EXPORT_SYMBOL(elevator_init);
@@ -564,25 +554,6 @@ void elv_drain_elevator(struct request_queue *q)
}
}
-void elv_quiesce_start(struct request_queue *q)
-{
- if (!q->elevator)
- return;
-
- spin_lock_irq(q->queue_lock);
- queue_flag_set(QUEUE_FLAG_ELVSWITCH, q);
- spin_unlock_irq(q->queue_lock);
-
- blk_drain_queue(q, false);
-}
-
-void elv_quiesce_end(struct request_queue *q)
-{
- spin_lock_irq(q->queue_lock);
- queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q);
- spin_unlock_irq(q->queue_lock);
-}
-
void __elv_add_request(struct request_queue *q, struct request *rq, int where)
{
trace_block_rq_insert(q, rq);
@@ -692,12 +663,13 @@ struct request *elv_former_request(struct request_queue *q, struct request *rq)
return NULL;
}
-int elv_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
+int elv_set_request(struct request_queue *q, struct request *rq,
+ struct bio *bio, gfp_t gfp_mask)
{
struct elevator_queue *e = q->elevator;
if (e->type->ops.elevator_set_req_fn)
- return e->type->ops.elevator_set_req_fn(q, rq, gfp_mask);
+ return e->type->ops.elevator_set_req_fn(q, rq, bio, gfp_mask);
return 0;
}
@@ -801,8 +773,9 @@ static struct kobj_type elv_ktype = {
.release = elevator_release,
};
-int __elv_register_queue(struct request_queue *q, struct elevator_queue *e)
+int elv_register_queue(struct request_queue *q)
{
+ struct elevator_queue *e = q->elevator;
int error;
error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched");
@@ -820,11 +793,6 @@ int __elv_register_queue(struct request_queue *q, struct elevator_queue *e)
}
return error;
}
-
-int elv_register_queue(struct request_queue *q)
-{
- return __elv_register_queue(q, q->elevator);
-}
EXPORT_SYMBOL(elv_register_queue);
void elv_unregister_queue(struct request_queue *q)
@@ -907,53 +875,60 @@ EXPORT_SYMBOL_GPL(elv_unregister);
*/
static int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
{
- struct elevator_queue *old_elevator, *e;
+ struct elevator_queue *old = q->elevator;
+ bool registered = old->registered;
int err;
- /* allocate new elevator */
- e = elevator_alloc(q, new_e);
- if (!e)
- return -ENOMEM;
+ /*
+ * Turn on BYPASS and drain all requests w/ elevator private data.
+ * Block layer doesn't call into a quiesced elevator - all requests
+ * are directly put on the dispatch list without elevator data
+ * using INSERT_BACK. All requests have SOFTBARRIER set and no
+ * merge happens either.
+ */
+ blk_queue_bypass_start(q);
+
+ /* unregister and clear all auxiliary data of the old elevator */
+ if (registered)
+ elv_unregister_queue(q);
+
+ spin_lock_irq(q->queue_lock);
+ ioc_clear_queue(q);
+ spin_unlock_irq(q->queue_lock);
- err = elevator_init_queue(q, e);
+ /* allocate, init and register new elevator */
+ err = -ENOMEM;
+ q->elevator = elevator_alloc(q, new_e);
+ if (!q->elevator)
+ goto fail_init;
+
+ err = new_e->ops.elevator_init_fn(q);
if (err) {
- kobject_put(&e->kobj);
- return err;
+ kobject_put(&q->elevator->kobj);
+ goto fail_init;
}
- /* turn on BYPASS and drain all requests w/ elevator private data */
- elv_quiesce_start(q);
-
- /* unregister old queue, register new one and kill old elevator */
- if (q->elevator->registered) {
- elv_unregister_queue(q);
- err = __elv_register_queue(q, e);
+ if (registered) {
+ err = elv_register_queue(q);
if (err)
goto fail_register;
}
- /* done, clear io_cq's, switch elevators and turn off BYPASS */
- spin_lock_irq(q->queue_lock);
- ioc_clear_queue(q);
- old_elevator = q->elevator;
- q->elevator = e;
- spin_unlock_irq(q->queue_lock);
-
- elevator_exit(old_elevator);
- elv_quiesce_end(q);
+ /* done, kill the old one and finish */
+ elevator_exit(old);
+ blk_queue_bypass_end(q);
- blk_add_trace_msg(q, "elv switch: %s", e->type->elevator_name);
+ blk_add_trace_msg(q, "elv switch: %s", new_e->elevator_name);
return 0;
fail_register:
- /*
- * switch failed, exit the new io scheduler and reattach the old
- * one again (along with re-adding the sysfs dir)
- */
- elevator_exit(e);
+ elevator_exit(q->elevator);
+fail_init:
+ /* switch failed, restore and re-register old elevator */
+ q->elevator = old;
elv_register_queue(q);
- elv_quiesce_end(q);
+ blk_queue_bypass_end(q);
return err;
}