Merge git://git.kernel.org/pub/scm/linux/kernel/git/bunk/trivial

[pandora-kernel.git] / block / elevator.c

diff --git a/block/elevator.c b/block/elevator.c
index 2982579..bc7baee 100644 (file)
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -27,7 +27,6 @@
 #include <linux/blkdev.h>
 #include <linux/elevator.h>
 #include <linux/bio.h>
-#include <linux/config.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/init.h>
@@ -121,16 +120,16 @@ static struct elevator_type *elevator_get(const char *name)
        return e;
 }
 
-static int elevator_attach(request_queue_t *q, struct elevator_queue *eq)
+static void *elevator_init_queue(request_queue_t *q, struct elevator_queue *eq)
 {
-       int ret = 0;
+       return eq->ops->elevator_init_fn(q, eq);
+}
 
+static void elevator_attach(request_queue_t *q, struct elevator_queue *eq,
+                          void *data)
+{
        q->elevator = eq;
-
-       if (eq->ops->elevator_init_fn)
-               ret = eq->ops->elevator_init_fn(q, eq);
-
-       return ret;
+       eq->elevator_data = data;
 }
 
 static char chosen_elevator[16];
@@ -181,6 +180,7 @@ int elevator_init(request_queue_t *q, char *name)
        struct elevator_type *e = NULL;
        struct elevator_queue *eq;
        int ret = 0;
+       void *data;
 
        INIT_LIST_HEAD(&q->queue_head);
        q->last_merge = NULL;
@@ -202,10 +202,13 @@ int elevator_init(request_queue_t *q, char *name)
        if (!eq)
                return -ENOMEM;
 
-       ret = elevator_attach(q, eq);
-       if (ret)
+       data = elevator_init_queue(q, eq);
+       if (!data) {
                kobject_put(&eq->kobj);
+               return -ENOMEM;
+       }
 
+       elevator_attach(q, eq, data);
        return ret;
 }
 
@@ -333,6 +336,7 @@ void elv_insert(request_queue_t *q, struct request *rq, int where)
 {
        struct list_head *pos;
        unsigned ordseq;
+       int unplug_it = 1;
 
        blk_add_trace_rq(q, rq, BLK_TA_INSERT);
 
@@ -399,6 +403,11 @@ void elv_insert(request_queue_t *q, struct request *rq, int where)
                }
 
                list_add_tail(&rq->queuelist, pos);
+               /*
+                * most requeues happen because of a busy condition, don't
+                * force unplug of the queue for that case.
+                */
+               unplug_it = 0;
                break;
 
        default:
@@ -407,7 +416,7 @@ void elv_insert(request_queue_t *q, struct request *rq, int where)
                BUG();
        }
 
-       if (blk_queue_plugged(q)) {
+       if (unplug_it && blk_queue_plugged(q)) {
                int nrq = q->rq.count[READ] + q->rq.count[WRITE]
                        - q->in_flight;
 
@@ -716,13 +725,16 @@ int elv_register_queue(struct request_queue *q)
        return error;
 }
 
+static void __elv_unregister_queue(elevator_t *e)
+{
+       kobject_uevent(&e->kobj, KOBJ_REMOVE);
+       kobject_del(&e->kobj);
+}
+
 void elv_unregister_queue(struct request_queue *q)
 {
-       if (q) {
-               elevator_t *e = q->elevator;
-               kobject_uevent(&e->kobj, KOBJ_REMOVE);
-               kobject_del(&e->kobj);
-       }
+       if (q)
+               __elv_unregister_queue(q->elevator);
 }
 
 int elv_register(struct elevator_type *e)
@@ -774,6 +786,7 @@ EXPORT_SYMBOL_GPL(elv_unregister);
 static int elevator_switch(request_queue_t *q, struct elevator_type *new_e)
 {
        elevator_t *old_elevator, *e;
+       void *data;
 
        /*
         * Allocate new elevator
@@ -782,6 +795,12 @@ static int elevator_switch(request_queue_t *q, struct elevator_type *new_e)
        if (!e)
                return 0;
 
+       data = elevator_init_queue(q, e);
+       if (!data) {
+               kobject_put(&e->kobj);
+               return 0;
+       }
+
        /*
         * Turn on BYPASS and drain all requests w/ elevator private data
         */
@@ -800,19 +819,19 @@ static int elevator_switch(request_queue_t *q, struct elevator_type *new_e)
                elv_drain_elevator(q);
        }
 
-       spin_unlock_irq(q->queue_lock);
-
        /*
-        * unregister old elevator data
+        * Remember old elevator.
         */
-       elv_unregister_queue(q);
        old_elevator = q->elevator;
 
        /*
         * attach and start new elevator
         */
-       if (elevator_attach(q, e))
-               goto fail;
+       elevator_attach(q, e, data);
+
+       spin_unlock_irq(q->queue_lock);
+
+       __elv_unregister_queue(old_elevator);
 
        if (elv_register_queue(q))
                goto fail_register;
@@ -830,13 +849,9 @@ fail_register:
         * one again (along with re-adding the sysfs dir)
         */
        elevator_exit(e);
-       e = NULL;
-fail:
        q->elevator = old_elevator;
        elv_register_queue(q);
        clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
-       if (e)
-               kobject_put(&e->kobj);
        return 0;
 }