diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index dba52b62cef850c0e2102b54caa8eb89ffe2422a..8830893e062ff901793cb7616f412fbc317be489 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -200,7 +200,7 @@ CFQ_CFQQ_FNS(sync);
static void cfq_dispatch_insert(struct request_queue *, struct request *);
static struct cfq_queue *cfq_get_queue(struct cfq_data *, int,
struct io_context *, gfp_t);
-static struct cfq_io_context *cfq_cic_rb_lookup(struct cfq_data *,
+static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *,
struct io_context *);
static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
@@ -609,7 +609,7 @@ cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
struct cfq_io_context *cic;
struct cfq_queue *cfqq;
- cic = cfq_cic_rb_lookup(cfqd, tsk->io_context);
+ cic = cfq_cic_lookup(cfqd, tsk->io_context);
if (!cic)
return NULL;
@@ -721,7 +721,7 @@ static int cfq_allow_merge(struct request_queue *q, struct request *rq,
* Lookup the cfqq that this bio will be queued with. Allow
* merge only if rq is queued there.
*/
- cic = cfq_cic_rb_lookup(cfqd, current->io_context);
+ cic = cfq_cic_lookup(cfqd, current->io_context);
if (!cic)
return 0;
@@ -1170,29 +1170,74 @@ static void cfq_put_queue(struct cfq_queue *cfqq)
kmem_cache_free(cfq_pool, cfqq);
}
-static void cfq_free_io_context(struct io_context *ioc)
+/*
+ * Call func for each cic attached to this ioc. Returns number of cic's seen.
+ */
+#define CIC_GANG_NR 16
+static unsigned int
+call_for_each_cic(struct io_context *ioc,
+ void (*func)(struct io_context *, struct cfq_io_context *))
{
- struct cfq_io_context *__cic;
- struct rb_node *n;
- int freed = 0;
+ struct cfq_io_context *cics[CIC_GANG_NR];
+ unsigned long index = 0;
+ unsigned int called = 0;
+ int nr;
- ioc->ioc_data = NULL;
+ rcu_read_lock();
- spin_lock(&ioc->lock);
+ do {
+ int i;
- while ((n = rb_first(&ioc->cic_root)) != NULL) {
- __cic = rb_entry(n, struct cfq_io_context, rb_node);
- rb_erase(&__cic->rb_node, &ioc->cic_root);
- kmem_cache_free(cfq_ioc_pool, __cic);
- freed++;
- }
+ /*
+ * 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;
+
+ called += nr;
+ index = 1 + (unsigned long) cics[nr - 1]->key;
+
+ for (i = 0; i < nr; i++)
+ func(ioc, cics[i]);
+ } while (nr == CIC_GANG_NR);
+
+ rcu_read_unlock();
+
+ return called;
+}
+
+static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
+{
+ unsigned long flags;
+
+ BUG_ON(!cic->dead_key);
+
+ spin_lock_irqsave(&ioc->lock, flags);
+ radix_tree_delete(&ioc->radix_root, cic->dead_key);
+ spin_unlock_irqrestore(&ioc->lock, flags);
+
+ kmem_cache_free(cfq_ioc_pool, 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.
+ */
+ 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);
-
- spin_unlock(&ioc->lock);
}
static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
@@ -1209,7 +1254,12 @@ static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
struct cfq_io_context *cic)
{
list_del_init(&cic->queue_list);
+
+ /*
+ * Make sure key == NULL is seen for dead queues
+ */
smp_wmb();
+ cic->dead_key = (unsigned long) cic->key;
cic->key = NULL;
if (cic->cfqq[ASYNC]) {
@@ -1223,16 +1273,18 @@ static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
}
}
-static void cfq_exit_single_io_context(struct cfq_io_context *cic)
+static void cfq_exit_single_io_context(struct io_context *ioc,
+ struct cfq_io_context *cic)
{
struct cfq_data *cfqd = cic->key;
if (cfqd) {
struct request_queue *q = cfqd->queue;
+ unsigned long flags;
- spin_lock_irq(q->queue_lock);
+ spin_lock_irqsave(q->queue_lock, flags);
__cfq_exit_single_io_context(cfqd, cic);
- spin_unlock_irq(q->queue_lock);
+ spin_unlock_irqrestore(q->queue_lock, flags);
}
}
@@ -1242,24 +1294,8 @@ static void cfq_exit_single_io_context(struct cfq_io_context *cic)
*/
static void cfq_exit_io_context(struct io_context *ioc)
{
- struct cfq_io_context *__cic;
- struct rb_node *n;
-
- ioc->ioc_data = NULL;
-
- spin_lock(&ioc->lock);
- /*
- * put the reference this task is holding to the various queues
- */
- n = rb_first(&ioc->cic_root);
- while (n != NULL) {
- __cic = rb_entry(n, struct cfq_io_context, rb_node);
-
- cfq_exit_single_io_context(__cic);
- n = rb_next(n);
- }
-
- spin_unlock(&ioc->lock);
+ rcu_assign_pointer(ioc->ioc_data, NULL);
+ call_for_each_cic(ioc, cfq_exit_single_io_context);
}
static struct cfq_io_context *
@@ -1323,7 +1359,8 @@ static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
cfq_clear_cfqq_prio_changed(cfqq);
}
-static inline void changed_ioprio(struct cfq_io_context *cic)
+static inline void changed_ioprio(struct io_context *ioc,
+ struct cfq_io_context *cic)
{
struct cfq_data *cfqd = cic->key;
struct cfq_queue *cfqq;
@@ -1353,22 +1390,8 @@ static inline void changed_ioprio(struct cfq_io_context *cic)
static void cfq_ioc_set_ioprio(struct io_context *ioc)
{
- struct cfq_io_context *cic;
- struct rb_node *n;
-
- spin_lock(&ioc->lock);
-
+ call_for_each_cic(ioc, changed_ioprio);
ioc->ioprio_changed = 0;
-
- n = rb_first(&ioc->cic_root);
- while (n != NULL) {
- cic = rb_entry(n, struct cfq_io_context, rb_node);
-
- changed_ioprio(cic);
- n = rb_next(n);
- }
-
- spin_unlock(&ioc->lock);
}
static struct cfq_queue *
@@ -1379,7 +1402,7 @@ cfq_find_alloc_queue(struct cfq_data *cfqd, int is_sync,
struct cfq_io_context *cic;
retry:
- cic = cfq_cic_rb_lookup(cfqd, ioc);
+ cic = cfq_cic_lookup(cfqd, ioc);
/* cic always exists here */
cfqq = cic_to_cfqq(cic, is_sync);
@@ -1480,28 +1503,42 @@ 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.
*/
static void
-cfq_drop_dead_cic(struct io_context *ioc, struct cfq_io_context *cic)
+cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
+ struct cfq_io_context *cic)
{
+ unsigned long flags;
+
WARN_ON(!list_empty(&cic->queue_list));
+ spin_lock_irqsave(&ioc->lock, flags);
+
if (ioc->ioc_data == cic)
- ioc->ioc_data = NULL;
+ rcu_assign_pointer(ioc->ioc_data, NULL);
- rb_erase(&cic->rb_node, &ioc->cic_root);
- kmem_cache_free(cfq_ioc_pool, cic);
- elv_ioc_count_dec(ioc_count);
+ radix_tree_delete(&ioc->radix_root, (unsigned long) cfqd);
+ spin_unlock_irqrestore(&ioc->lock, flags);
+
+ cfq_cic_free(cic);
}
static struct cfq_io_context *
-cfq_cic_rb_lookup(struct cfq_data *cfqd, struct io_context *ioc)
+cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
{
- struct rb_node *n;
struct cfq_io_context *cic;
- void *k, *key = cfqd;
+ void *k;
if (unlikely(!ioc))
return NULL;
@@ -1509,79 +1546,65 @@ cfq_cic_rb_lookup(struct cfq_data *cfqd, struct io_context *ioc)
/*
* we maintain a last-hit cache, to avoid browsing over the tree
*/
- cic = ioc->ioc_data;
+ cic = rcu_dereference(ioc->ioc_data);
if (cic && cic->key == cfqd)
return cic;
- spin_lock(&ioc->lock);
-restart:
- n = ioc->cic_root.rb_node;
- while (n) {
- cic = rb_entry(n, struct cfq_io_context, rb_node);
+ do {
+ rcu_read_lock();
+ cic = radix_tree_lookup(&ioc->radix_root, (unsigned long) cfqd);
+ rcu_read_unlock();
+ if (!cic)
+ break;
/* ->key must be copied to avoid race with cfq_exit_queue() */
k = cic->key;
if (unlikely(!k)) {
- cfq_drop_dead_cic(ioc, cic);
- goto restart;
+ cfq_drop_dead_cic(cfqd, ioc, cic);
+ continue;
}
- if (key < k)
- n = n->rb_left;
- else if (key > k)
- n = n->rb_right;
- else {
- ioc->ioc_data = cic;
- spin_unlock(&ioc->lock);
- return cic;
- }
- }
+ rcu_assign_pointer(ioc->ioc_data, cic);
+ break;
+ } while (1);
- spin_unlock(&ioc->lock);
- return NULL;
+ return cic;
}
-static inline void
+/*
+ * Add cic into ioc, using cfqd as the search key. This enables us to lookup
+ * the process specific cfq io context when entered from the block layer.
+ * Also adds the cic to a per-cfqd list, used when this queue is removed.
+ */
+static inline int
cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
- struct cfq_io_context *cic)
+ struct cfq_io_context *cic, gfp_t gfp_mask)
{
- struct rb_node **p;
- struct rb_node *parent;
- struct cfq_io_context *__cic;
unsigned long flags;
- void *k;
+ int ret;
- spin_lock(&ioc->lock);
- cic->ioc = ioc;
- cic->key = cfqd;
+ ret = radix_tree_preload(gfp_mask);
+ if (!ret) {
+ cic->ioc = ioc;
+ cic->key = cfqd;
-restart:
- parent = NULL;
- p = &ioc->cic_root.rb_node;
- while (*p) {
- parent = *p;
- __cic = rb_entry(parent, struct cfq_io_context, rb_node);
- /* ->key must be copied to avoid race with cfq_exit_queue() */
- k = __cic->key;
- if (unlikely(!k)) {
- cfq_drop_dead_cic(ioc, __cic);
- goto restart;
- }
+ spin_lock_irqsave(&ioc->lock, flags);
+ ret = radix_tree_insert(&ioc->radix_root,
+ (unsigned long) cfqd, cic);
+ spin_unlock_irqrestore(&ioc->lock, flags);
- if (cic->key < k)
- p = &(*p)->rb_left;
- else if (cic->key > k)
- p = &(*p)->rb_right;
- else
- BUG();
+ radix_tree_preload_end();
+
+ if (!ret) {
+ spin_lock_irqsave(cfqd->queue->queue_lock, flags);
+ list_add(&cic->queue_list, &cfqd->cic_list);
+ spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
+ }
}
- rb_link_node(&cic->rb_node, parent, p);
- rb_insert_color(&cic->rb_node, &ioc->cic_root);
+ if (ret)
+ printk(KERN_ERR "cfq: cic link failed!\n");
- spin_lock_irqsave(cfqd->queue->queue_lock, flags);
- list_add(&cic->queue_list, &cfqd->cic_list);
- spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
- spin_unlock(&ioc->lock);
+ return ret;
}
/*
@@ -1601,7 +1624,7 @@ cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
if (!ioc)
return NULL;
- cic = cfq_cic_rb_lookup(cfqd, ioc);
+ cic = cfq_cic_lookup(cfqd, ioc);
if (cic)
goto out;
@@ -1609,13 +1632,17 @@ cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
if (cic == NULL)
goto err;
- cfq_cic_link(cfqd, ioc, cic);
+ if (cfq_cic_link(cfqd, ioc, cic, gfp_mask))
+ goto err_free;
+
out:
smp_read_barrier_depends();
if (unlikely(ioc->ioprio_changed))
cfq_ioc_set_ioprio(ioc);
return cic;
+err_free:
+ cfq_cic_free(cic);
err:
put_io_context(ioc);
return NULL;
@@ -1909,7 +1936,7 @@ static int cfq_may_queue(struct request_queue *q, int rw)
* so just lookup a possibly existing queue, or return 'may queue'
* if that fails
*/
- cic = cfq_cic_rb_lookup(cfqd, tsk->io_context);
+ cic = cfq_cic_lookup(cfqd, tsk->io_context);
if (!cic)
return ELV_MQUEUE_MAY;
@@ -2174,7 +2201,7 @@ static int __init cfq_slab_setup(void)
if (!cfq_pool)
goto fail;
- cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0);
+ cfq_ioc_pool = KMEM_CACHE(cfq_io_context, SLAB_DESTROY_BY_RCU);
if (!cfq_ioc_pool)
goto fail;
diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index d4550ecae4431fd82610c1c8ca96255a7a94701f..b901db63f6ae082f1df23e3227c9ddd2e56d61d1 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -3853,6 +3853,21 @@ int __init blk_dev_init(void)
return 0;
}
+static void cfq_dtor(struct io_context *ioc)
+{
+ struct cfq_io_context *cic[1];
+ int r;
+
+ /*
+ * We don't have a specific key to lookup with, so use the gang
+ * lookup to just retrieve the first item stored. The cfq exit
+ * function will iterate the full tree, so any member will do.
+ */
+ r = radix_tree_gang_lookup(&ioc->radix_root, (void **) cic, 0, 1);
+ if (r > 0)
+ cic[0]->dtor(ioc);
+}
+
/*
* IO Context helper functions. put_io_context() returns 1 if there are no
* more users of this io context, 0 otherwise.
@@ -3865,18 +3880,11 @@ int put_io_context(struct io_context *ioc)
BUG_ON(atomic_read(&ioc->refcount) == 0);
if (atomic_dec_and_test(&ioc->refcount)) {
- struct cfq_io_context *cic;
-
rcu_read_lock();
if (ioc->aic && ioc->aic->dtor)
ioc->aic->dtor(ioc->aic);
- if (ioc->cic_root.rb_node != NULL) {
- struct rb_node *n = rb_first(&ioc->cic_root);
-
- cic = rb_entry(n, struct cfq_io_context, rb_node);
- cic->dtor(ioc);
- }
rcu_read_unlock();
+ cfq_dtor(ioc);
kmem_cache_free(iocontext_cachep, ioc);
return 1;
@@ -3885,11 +3893,26 @@ int put_io_context(struct io_context *ioc)
}
EXPORT_SYMBOL(put_io_context);
+static void cfq_exit(struct io_context *ioc)
+{
+ struct cfq_io_context *cic[1];
+ int r;
+
+ rcu_read_lock();
+ /*
+ * See comment for cfq_dtor()
+ */
+ r = radix_tree_gang_lookup(&ioc->radix_root, (void **) cic, 0, 1);
+ rcu_read_unlock();
+
+ if (r > 0)
+ cic[0]->exit(ioc);
+}
+
/* Called by the exitting task */
void exit_io_context(void)
{
struct io_context *ioc;
- struct cfq_io_context *cic;
task_lock(current);
ioc = current->io_context;
@@ -3899,11 +3922,7 @@ void exit_io_context(void)
if (atomic_dec_and_test(&ioc->nr_tasks)) {
if (ioc->aic && ioc->aic->exit)
ioc->aic->exit(ioc->aic);
- if (ioc->cic_root.rb_node != NULL) {
- cic = rb_entry(rb_first(&ioc->cic_root),
- struct cfq_io_context, rb_node);
- cic->exit(ioc);
- }
+ cfq_exit(ioc);
put_io_context(ioc);
}
@@ -3923,7 +3942,7 @@ struct io_context *alloc_io_context(gfp_t gfp_flags, int node)
ret->last_waited = jiffies; /* doesn't matter... */
ret->nr_batch_requests = 0; /* because this is 0 */
ret->aic = NULL;
- ret->cic_root.rb_node = NULL;
+ INIT_RADIX_TREE(&ret->radix_root, GFP_ATOMIC | __GFP_HIGH);
ret->ioc_data = NULL;
}
diff --git a/include/linux/iocontext.h b/include/linux/iocontext.h
index cd44d458124ae21d4a57d88d571914dceede0738..593b222d9dcc25334be5ca6d05dc0a5ab413f5f5 100644
--- a/include/linux/iocontext.h
+++ b/include/linux/iocontext.h
@@ -1,6 +1,8 @@
#ifndef IOCONTEXT_H
#define IOCONTEXT_H
+#include <linux/radix-tree.h>
+
/*
* This is the per-process anticipatory I/O scheduler state.
*/
@@ -29,8 +31,8 @@ struct as_io_context {
struct cfq_queue;
struct cfq_io_context {
- struct rb_node rb_node;
void *key;
+ unsigned long dead_key;
struct cfq_queue *cfqq[2];
@@ -74,7 +76,7 @@ struct io_context {
int nr_batch_requests; /* Number of requests left in the batch */
struct as_io_context *aic;
- struct rb_root cic_root;
+ struct radix_tree_root radix_root;
void *ioc_data;
};