1 files changed, 38 insertions, 52 deletions

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index ca198e61fa65..f4e1006c253d 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1143,43 +1143,37 @@ static void cfq_put_queue(struct cfq_queue *cfqq)
 }
 
 /*
- * Call func for each cic attached to this ioc. Returns number of cic's seen.
+ * Call func for each cic attached to this ioc.
  */
-#define CIC_GANG_NR     16
-static unsigned int
+static void
 call_for_each_cic(struct io_context *ioc,
                   void (*func)(struct io_context *, struct cfq_io_context *))
 {
-        struct cfq_io_context *cics[CIC_GANG_NR];
-        unsigned long index = 0;
-        unsigned int called = 0;
-        int nr;
+        struct cfq_io_context *cic;
+        struct hlist_node *n;
 
         rcu_read_lock();
+        hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
+                func(ioc, cic);
+        rcu_read_unlock();
+}
 
-        do {
-                int i;
-
-                /*
-                 * Perhaps there's a better way - this just gang lookups from
-                 * 0 to the end, restarting after each CIC_GANG_NR from the
-                 * last key + 1.
-                 */
-                nr = radix_tree_gang_lookup(&ioc->radix_root, (void **) cics,
-                                                index, CIC_GANG_NR);
-                if (!nr)
-                        break;
+static void cfq_cic_free_rcu(struct rcu_head *head)
+{
+        struct cfq_io_context *cic;
 
-                called += nr;
-                index = 1 + (unsigned long) cics[nr - 1]->key;
+        cic = container_of(head, struct cfq_io_context, rcu_head);
 
-                for (i = 0; i < nr; i++)
-                        func(ioc, cics[i]);
-        } while (nr == CIC_GANG_NR);
+        kmem_cache_free(cfq_ioc_pool, cic);
+        elv_ioc_count_dec(ioc_count);
 
-        rcu_read_unlock();
+        if (ioc_gone && !elv_ioc_count_read(ioc_count))
+                complete(ioc_gone);
+}
 
-        return called;
+static void cfq_cic_free(struct cfq_io_context *cic)
+{
+        call_rcu(&cic->rcu_head, cfq_cic_free_rcu);
 }
 
 static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
@@ -1190,26 +1184,21 @@ static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
 
         spin_lock_irqsave(&ioc->lock, flags);
         radix_tree_delete(&ioc->radix_root, cic->dead_key);
+        hlist_del_rcu(&cic->cic_list);
         spin_unlock_irqrestore(&ioc->lock, flags);
 
-        kmem_cache_free(cfq_ioc_pool, cic);
+        cfq_cic_free(cic);
 }
 
 static void cfq_free_io_context(struct io_context *ioc)
 {
-        int freed;
-
         /*
-         * ioc->refcount is zero here, so no more cic's are allowed to be
-         * linked into this ioc. So it should be ok to iterate over the known
-         * list, we will see all cic's since no new ones are added.
+         * ioc->refcount is zero here, or we are called from elv_unregister(),
+         * so no more cic's are allowed to be linked into this ioc.  So it
+         * should be ok to iterate over the known list, we will see all cic's
+         * since no new ones are added.
          */
-        freed = call_for_each_cic(ioc, cic_free_func);
-
-        elv_ioc_count_mod(ioc_count, -freed);
-
-        if (ioc_gone && !elv_ioc_count_read(ioc_count))
-                complete(ioc_gone);
+        call_for_each_cic(ioc, cic_free_func);
 }
 
 static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
@@ -1225,6 +1214,8 @@ static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
                                          struct cfq_io_context *cic)
 {
+        struct io_context *ioc = cic->ioc;
+
         list_del_init(&cic->queue_list);
 
         /*
@@ -1234,6 +1225,9 @@ static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
         cic->dead_key = (unsigned long) cic->key;
         cic->key = NULL;
 
+        if (ioc->ioc_data == cic)
+                rcu_assign_pointer(ioc->ioc_data, NULL);
+
         if (cic->cfqq[ASYNC]) {
                 cfq_exit_cfqq(cfqd, cic->cfqq[ASYNC]);
                 cic->cfqq[ASYNC] = NULL;
@@ -1266,7 +1260,6 @@ static void cfq_exit_single_io_context(struct io_context *ioc,
  */
 static void cfq_exit_io_context(struct io_context *ioc)
 {
-        rcu_assign_pointer(ioc->ioc_data, NULL);
         call_for_each_cic(ioc, cfq_exit_single_io_context);
 }
 
@@ -1280,6 +1273,7 @@ cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
         if (cic) {
                 cic->last_end_request = jiffies;
                 INIT_LIST_HEAD(&cic->queue_list);
+                INIT_HLIST_NODE(&cic->cic_list);
                 cic->dtor = cfq_free_io_context;
                 cic->exit = cfq_exit_io_context;
                 elv_ioc_count_inc(ioc_count);
@@ -1475,15 +1469,6 @@ cfq_get_queue(struct cfq_data *cfqd, int is_sync, struct io_context *ioc,
         return cfqq;
 }
 
-static void cfq_cic_free(struct cfq_io_context *cic)
-{
-        kmem_cache_free(cfq_ioc_pool, cic);
-        elv_ioc_count_dec(ioc_count);
-
-        if (ioc_gone && !elv_ioc_count_read(ioc_count))
-                complete(ioc_gone);
-}
-
 /*
  * We drop cfq io contexts lazily, so we may find a dead one.
  */
@@ -1497,10 +1482,10 @@ cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
 
         spin_lock_irqsave(&ioc->lock, flags);
 
-        if (ioc->ioc_data == cic)
-                rcu_assign_pointer(ioc->ioc_data, NULL);
+        BUG_ON(ioc->ioc_data == cic);
 
         radix_tree_delete(&ioc->radix_root, (unsigned long) cfqd);
+        hlist_del_rcu(&cic->cic_list);
         spin_unlock_irqrestore(&ioc->lock, flags);
 
         cfq_cic_free(cic);
@@ -1561,6 +1546,8 @@ static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
                 spin_lock_irqsave(&ioc->lock, flags);
                 ret = radix_tree_insert(&ioc->radix_root,
                                                 (unsigned long) cfqd, cic);
+                if (!ret)
+                        hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list);
                 spin_unlock_irqrestore(&ioc->lock, flags);
 
                 radix_tree_preload_end();
@@ -2152,7 +2139,7 @@ static int __init cfq_slab_setup(void)
         if (!cfq_pool)
                 goto fail;
 
-        cfq_ioc_pool = KMEM_CACHE(cfq_io_context, SLAB_DESTROY_BY_RCU);
+        cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0);
         if (!cfq_ioc_pool)
                 goto fail;
 
@@ -2300,7 +2287,6 @@ static void __exit cfq_exit(void)
         smp_wmb();
         if (elv_ioc_count_read(ioc_count))
                 wait_for_completion(ioc_gone);
-        synchronize_rcu();
         cfq_slab_kill();
 }