[BLOCK] fix string handling in elv_iosched_store

[karo-tx-linux.git] / block / elevator.c

diff --git a/block/elevator.c b/block/elevator.c
index d4a49a3df829674bbb4bb476f271fc721c6fa9f3..cacfff7418e459c235faf026ebcafad7d77708bd 100644 (file)
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -155,9 +155,10 @@ static void elevator_setup_default(void)
        /*
         * If the given scheduler is not available, fall back to no-op.
         */
-       if (!(e = elevator_find(chosen_elevator)))
+       if ((e = elevator_find(chosen_elevator)))
+               elevator_put(e);
+       else
                strcpy(chosen_elevator, "noop");
-       elevator_put(e);
 }
 
 static int __init elevator_setup(char *str)
@@ -190,14 +191,14 @@ int elevator_init(request_queue_t *q, char *name)
 
        eq = kmalloc(sizeof(struct elevator_queue), GFP_KERNEL);
        if (!eq) {
-               elevator_put(e->elevator_type);
+               elevator_put(e);
                return -ENOMEM;
        }
 
        ret = elevator_attach(q, e, eq);
        if (ret) {
                kfree(eq);
-               elevator_put(e->elevator_type);
+               elevator_put(e);
        }
 
        return ret;
@@ -225,6 +226,7 @@ void elv_dispatch_sort(request_queue_t *q, struct request *rq)
 
        if (q->last_merge == rq)
                q->last_merge = NULL;
+       q->nr_sorted--;
 
        boundary = q->end_sector;
 
@@ -283,6 +285,7 @@ void elv_merge_requests(request_queue_t *q, struct request *rq,
 
        if (e->ops->elevator_merge_req_fn)
                e->ops->elevator_merge_req_fn(q, rq, next);
+       q->nr_sorted--;
 
        q->last_merge = rq;
 }
@@ -314,6 +317,20 @@ void elv_requeue_request(request_queue_t *q, struct request *rq)
        __elv_add_request(q, rq, ELEVATOR_INSERT_FRONT, 0);
 }
 
+static void elv_drain_elevator(request_queue_t *q)
+{
+       static int printed;
+       while (q->elevator->ops->elevator_dispatch_fn(q, 1))
+               ;
+       if (q->nr_sorted == 0)
+               return;
+       if (printed++ < 10) {
+               printk(KERN_ERR "%s: forced dispatching is broken "
+                      "(nr_sorted=%u), please report this\n",
+                      q->elevator->elevator_type->elevator_name, q->nr_sorted);
+       }
+}
+
 void __elv_add_request(request_queue_t *q, struct request *rq, int where,
                       int plug)
 {
@@ -348,9 +365,7 @@ void __elv_add_request(request_queue_t *q, struct request *rq, int where,
 
        case ELEVATOR_INSERT_BACK:
                rq->flags |= REQ_SOFTBARRIER;
-
-               while (q->elevator->ops->elevator_dispatch_fn(q, 1))
-                       ;
+               elv_drain_elevator(q);
                list_add_tail(&rq->queuelist, &q->queue_head);
                /*
                 * We kick the queue here for the following reasons.
@@ -369,6 +384,7 @@ void __elv_add_request(request_queue_t *q, struct request *rq, int where,
        case ELEVATOR_INSERT_SORT:
                BUG_ON(!blk_fs_request(rq));
                rq->flags |= REQ_SORTED;
+               q->nr_sorted++;
                if (q->last_merge == NULL && rq_mergeable(rq))
                        q->last_merge = rq;
                /*
@@ -691,13 +707,15 @@ static void elevator_switch(request_queue_t *q, struct elevator_type *new_e)
 
        set_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
 
-       while (q->elevator->ops->elevator_dispatch_fn(q, 1))
-               ;
+       elv_drain_elevator(q);
 
        while (q->rq.elvpriv) {
+               blk_remove_plug(q);
+               q->request_fn(q);
                spin_unlock_irq(q->queue_lock);
                msleep(10);
                spin_lock_irq(q->queue_lock);
+               elv_drain_elevator(q);
        }
 
        spin_unlock_irq(q->queue_lock);
@@ -744,13 +762,15 @@ error:
 ssize_t elv_iosched_store(request_queue_t *q, const char *name, size_t count)
 {
        char elevator_name[ELV_NAME_MAX];
+       size_t len;
        struct elevator_type *e;
 
-       memset(elevator_name, 0, sizeof(elevator_name));
-       strncpy(elevator_name, name, sizeof(elevator_name));
+       elevator_name[sizeof(elevator_name) - 1] = '\0';
+       strncpy(elevator_name, name, sizeof(elevator_name) - 1);
+       len = strlen(elevator_name);
 
-       if (elevator_name[strlen(elevator_name) - 1] == '\n')
-               elevator_name[strlen(elevator_name) - 1] = '\0';
+       if (len && elevator_name[len - 1] == '\n')
+               elevator_name[len - 1] = '\0';
 
        e = elevator_get(elevator_name);
        if (!e) {