[PATCH] make cfq_exit_queue() prune the cfq_io_context for that queue

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 3bacf4b..3fc6e50 100644 (file)
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -177,6 +177,8 @@ struct cfq_data {
        unsigned int cfq_slice_async_rq;
        unsigned int cfq_slice_idle;
        unsigned int cfq_max_depth;
+
+       struct list_head cic_list;
 };
 
 /*
@@ -1215,7 +1217,12 @@ static void cfq_free_io_context(struct cfq_io_context *cic)
 static void cfq_exit_single_io_context(struct cfq_io_context *cic)
 {
        struct cfq_data *cfqd = cic->key;
-       request_queue_t *q = cfqd->queue;
+       request_queue_t *q;
+
+       if (!cfqd)
+               return;
+
+       q = cfqd->queue;
 
        WARN_ON(!irqs_disabled());
 
@@ -1236,6 +1243,7 @@ static void cfq_exit_single_io_context(struct cfq_io_context *cic)
        }
 
        cic->key = NULL;
+       list_del_init(&cic->queue_list);
        spin_unlock(q->queue_lock);
 }
 
@@ -1254,12 +1262,14 @@ static void cfq_exit_io_context(struct cfq_io_context *cic)
        /*
         * put the reference this task is holding to the various queues
         */
+       read_lock(&cfq_exit_lock);
        list_for_each(entry, &cic->list) {
                __cic = list_entry(entry, struct cfq_io_context, list);
                cfq_exit_single_io_context(__cic);
        }
 
        cfq_exit_single_io_context(cic);
+       read_unlock(&cfq_exit_lock);
        local_irq_restore(flags);
 }
 
@@ -1279,6 +1289,7 @@ cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
                cic->ttime_mean = 0;
                cic->dtor = cfq_free_io_context;
                cic->exit = cfq_exit_io_context;
+               INIT_LIST_HEAD(&cic->queue_list);
        }
 
        return cic;
@@ -1446,6 +1457,7 @@ cfq_get_io_context(struct cfq_data *cfqd, pid_t pid, gfp_t gfp_mask)
        if (!ioc)
                return NULL;
 
+restart:
        if ((cic = ioc->cic) == NULL) {
                cic = cfq_alloc_io_context(cfqd, gfp_mask);
 
@@ -1461,6 +1473,7 @@ cfq_get_io_context(struct cfq_data *cfqd, pid_t pid, gfp_t gfp_mask)
                read_lock(&cfq_exit_lock);
                ioc->set_ioprio = cfq_ioc_set_ioprio;
                ioc->cic = cic;
+               list_add(&cic->queue_list, &cfqd->cic_list);
                read_unlock(&cfq_exit_lock);
        } else {
                struct cfq_io_context *__cic;
@@ -1471,6 +1484,19 @@ cfq_get_io_context(struct cfq_data *cfqd, pid_t pid, gfp_t gfp_mask)
                if (cic->key == cfqd)
                        goto out;
 
+               if (unlikely(!cic->key)) {
+                       read_lock(&cfq_exit_lock);
+                       if (list_empty(&cic->list))
+                               ioc->cic = NULL;
+                       else
+                               ioc->cic = list_entry(cic->list.next,
+                                                     struct cfq_io_context,
+                                                     list);
+                       read_unlock(&cfq_exit_lock);
+                       kmem_cache_free(cfq_ioc_pool, cic);
+                       goto restart;
+               }
+
                /*
                 * cic exists, check if we already are there. linear search
                 * should be ok here, the list will usually not be more than
@@ -1485,6 +1511,13 @@ cfq_get_io_context(struct cfq_data *cfqd, pid_t pid, gfp_t gfp_mask)
                                cic = __cic;
                                goto out;
                        }
+                       if (unlikely(!__cic->key)) {
+                               read_lock(&cfq_exit_lock);
+                               list_del(&__cic->list);
+                               read_unlock(&cfq_exit_lock);
+                               kmem_cache_free(cfq_ioc_pool, __cic);
+                               goto restart;
+                       }
                }
 
                /*
@@ -1499,6 +1532,7 @@ cfq_get_io_context(struct cfq_data *cfqd, pid_t pid, gfp_t gfp_mask)
                __cic->key = cfqd;
                read_lock(&cfq_exit_lock);
                list_add(&__cic->list, &cic->list);
+               list_add(&__cic->queue_list, &cfqd->cic_list);
                read_unlock(&cfq_exit_lock);
                cic = __cic;
        }
@@ -2104,8 +2138,30 @@ static void cfq_put_cfqd(struct cfq_data *cfqd)
 static void cfq_exit_queue(elevator_t *e)
 {
        struct cfq_data *cfqd = e->elevator_data;
+       request_queue_t *q = cfqd->queue;
 
        cfq_shutdown_timer_wq(cfqd);
+       write_lock(&cfq_exit_lock);
+       spin_lock_irq(q->queue_lock);
+       if (cfqd->active_queue)
+               __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
+       while(!list_empty(&cfqd->cic_list)) {
+               struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
+                                                       struct cfq_io_context,
+                                                       queue_list);
+               if (cic->cfqq[ASYNC]) {
+                       cfq_put_queue(cic->cfqq[ASYNC]);
+                       cic->cfqq[ASYNC] = NULL;
+               }
+               if (cic->cfqq[SYNC]) {
+                       cfq_put_queue(cic->cfqq[SYNC]);
+                       cic->cfqq[SYNC] = NULL;
+               }
+               cic->key = NULL;
+               list_del_init(&cic->queue_list);
+       }
+       spin_unlock_irq(q->queue_lock);
+       write_unlock(&cfq_exit_lock);
        cfq_put_cfqd(cfqd);
 }
 
@@ -2127,6 +2183,7 @@ static int cfq_init_queue(request_queue_t *q, elevator_t *e)
        INIT_LIST_HEAD(&cfqd->cur_rr);
        INIT_LIST_HEAD(&cfqd->idle_rr);
        INIT_LIST_HEAD(&cfqd->empty_list);
+       INIT_LIST_HEAD(&cfqd->cic_list);
 
        cfqd->crq_hash = kmalloc(sizeof(struct hlist_head) * CFQ_MHASH_ENTRIES, GFP_KERNEL);
        if (!cfqd->crq_hash)

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index e19cb63..80518f7 100644 (file)
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -69,6 +69,8 @@ struct cfq_io_context {
        unsigned long ttime_samples;
        unsigned long ttime_mean;
 
+       struct list_head queue_list;
+
        void (*dtor)(struct cfq_io_context *);
        void (*exit)(struct cfq_io_context *);
 };