/* Throttling is performed over 100ms slice and after that slice is renewed */
static unsigned long throtl_slice = HZ/10; /* 100 ms */
+static struct blkio_policy_type blkio_policy_throtl;
+
/* A workqueue to queue throttle related work */
static struct workqueue_struct *kthrotld_workqueue;
static void throtl_schedule_delayed_work(struct throtl_data *td,
*/
unsigned long disptime;
- struct blkio_group blkg;
atomic_t ref;
unsigned int flags;
int limits_changed;
};
+static inline struct throtl_grp *blkg_to_tg(struct blkio_group *blkg)
+{
+ return blkg_to_pdata(blkg, &blkio_policy_throtl);
+}
+
+static inline struct blkio_group *tg_to_blkg(struct throtl_grp *tg)
+{
+ return pdata_to_blkg(tg, &blkio_policy_throtl);
+}
+
enum tg_state_flags {
THROTL_TG_FLAG_on_rr = 0, /* on round-robin busy list */
};
#define throtl_log_tg(td, tg, fmt, args...) \
blk_add_trace_msg((td)->queue, "throtl %s " fmt, \
- blkg_path(&(tg)->blkg), ##args); \
+ blkg_path(tg_to_blkg(tg)), ##args); \
#define throtl_log(td, fmt, args...) \
blk_add_trace_msg((td)->queue, "throtl " fmt, ##args)
-static inline struct throtl_grp *tg_of_blkg(struct blkio_group *blkg)
-{
- if (blkg)
- return container_of(blkg, struct throtl_grp, blkg);
-
- return NULL;
-}
-
static inline unsigned int total_nr_queued(struct throtl_data *td)
{
return td->nr_queued[0] + td->nr_queued[1];
static void throtl_free_tg(struct rcu_head *head)
{
- struct throtl_grp *tg;
+ struct throtl_grp *tg = container_of(head, struct throtl_grp, rcu_head);
+ struct blkio_group *blkg = tg_to_blkg(tg);
- tg = container_of(head, struct throtl_grp, rcu_head);
- free_percpu(tg->blkg.stats_cpu);
- kfree(tg);
+ free_percpu(blkg->stats_cpu);
+ kfree(blkg->pd);
+ kfree(blkg);
}
static void throtl_put_tg(struct throtl_grp *tg)
{
+ struct blkio_group *blkg = tg_to_blkg(tg);
+
BUG_ON(atomic_read(&tg->ref) <= 0);
if (!atomic_dec_and_test(&tg->ref))
return;
+ /* release the extra blkcg reference this blkg has been holding */
+ css_put(&blkg->blkcg->css);
+
/*
* A group is freed in rcu manner. But having an rcu lock does not
* mean that one can access all the fields of blkg and assume these
call_rcu(&tg->rcu_head, throtl_free_tg);
}
-static void throtl_init_group(struct throtl_grp *tg)
+static void throtl_init_blkio_group(struct blkio_group *blkg)
{
+ struct throtl_grp *tg = blkg_to_tg(blkg);
+
INIT_HLIST_NODE(&tg->tg_node);
RB_CLEAR_NODE(&tg->rb_node);
bio_list_init(&tg->bio_lists[0]);
bio_list_init(&tg->bio_lists[1]);
tg->limits_changed = false;
- /* Practically unlimited BW */
- tg->bps[0] = tg->bps[1] = -1;
- tg->iops[0] = tg->iops[1] = -1;
+ tg->bps[READ] = -1;
+ tg->bps[WRITE] = -1;
+ tg->iops[READ] = -1;
+ tg->iops[WRITE] = -1;
/*
* Take the initial reference that will be released on destroy
atomic_set(&tg->ref, 1);
}
-/* Should be called with rcu read lock held (needed for blkcg) */
-static void
-throtl_add_group_to_td_list(struct throtl_data *td, struct throtl_grp *tg)
+static void throtl_link_blkio_group(struct request_queue *q,
+ struct blkio_group *blkg)
{
+ struct throtl_data *td = q->td;
+ struct throtl_grp *tg = blkg_to_tg(blkg);
+
hlist_add_head(&tg->tg_node, &td->tg_list);
td->nr_undestroyed_grps++;
}
-static void
-__throtl_tg_fill_dev_details(struct throtl_data *td, struct throtl_grp *tg)
-{
- struct backing_dev_info *bdi = &td->queue->backing_dev_info;
- unsigned int major, minor;
-
- if (!tg || tg->blkg.dev)
- return;
-
- /*
- * Fill in device details for a group which might not have been
- * filled at group creation time as queue was being instantiated
- * and driver had not attached a device yet
- */
- if (bdi->dev && dev_name(bdi->dev)) {
- sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
- tg->blkg.dev = MKDEV(major, minor);
- }
-}
-
-/*
- * Should be called with without queue lock held. Here queue lock will be
- * taken rarely. It will be taken only once during life time of a group
- * if need be
- */
-static void
-throtl_tg_fill_dev_details(struct throtl_data *td, struct throtl_grp *tg)
-{
- if (!tg || tg->blkg.dev)
- return;
-
- spin_lock_irq(td->queue->queue_lock);
- __throtl_tg_fill_dev_details(td, tg);
- spin_unlock_irq(td->queue->queue_lock);
-}
-
-static void throtl_init_add_tg_lists(struct throtl_data *td,
- struct throtl_grp *tg, struct blkio_cgroup *blkcg)
-{
- __throtl_tg_fill_dev_details(td, tg);
-
- /* Add group onto cgroup list */
- blkiocg_add_blkio_group(blkcg, &tg->blkg, (void *)td,
- tg->blkg.dev, BLKIO_POLICY_THROTL);
-
- tg->bps[READ] = blkcg_get_read_bps(blkcg, tg->blkg.dev);
- tg->bps[WRITE] = blkcg_get_write_bps(blkcg, tg->blkg.dev);
- tg->iops[READ] = blkcg_get_read_iops(blkcg, tg->blkg.dev);
- tg->iops[WRITE] = blkcg_get_write_iops(blkcg, tg->blkg.dev);
-
- throtl_add_group_to_td_list(td, tg);
-}
-
-/* Should be called without queue lock and outside of rcu period */
-static struct throtl_grp *throtl_alloc_tg(struct throtl_data *td)
-{
- struct throtl_grp *tg = NULL;
- int ret;
-
- tg = kzalloc_node(sizeof(*tg), GFP_ATOMIC, td->queue->node);
- if (!tg)
- return NULL;
-
- ret = blkio_alloc_blkg_stats(&tg->blkg);
-
- if (ret) {
- kfree(tg);
- return NULL;
- }
-
- throtl_init_group(tg);
- return tg;
-}
-
static struct
-throtl_grp *throtl_find_tg(struct throtl_data *td, struct blkio_cgroup *blkcg)
+throtl_grp *throtl_lookup_tg(struct throtl_data *td, struct blkio_cgroup *blkcg)
{
- struct throtl_grp *tg = NULL;
- void *key = td;
-
/*
* This is the common case when there are no blkio cgroups.
- * Avoid lookup in this case
- */
+ * Avoid lookup in this case
+ */
if (blkcg == &blkio_root_cgroup)
- tg = td->root_tg;
- else
- tg = tg_of_blkg(blkiocg_lookup_group(blkcg, key));
+ return td->root_tg;
- __throtl_tg_fill_dev_details(td, tg);
- return tg;
+ return blkg_to_tg(blkg_lookup(blkcg, td->queue, BLKIO_POLICY_THROTL));
}
-static struct throtl_grp * throtl_get_tg(struct throtl_data *td)
+static struct throtl_grp *throtl_lookup_create_tg(struct throtl_data *td,
+ struct blkio_cgroup *blkcg)
{
- struct throtl_grp *tg = NULL, *__tg = NULL;
- struct blkio_cgroup *blkcg;
struct request_queue *q = td->queue;
-
- /* no throttling for dead queue */
- if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)))
- return NULL;
-
- rcu_read_lock();
- blkcg = task_blkio_cgroup(current);
- tg = throtl_find_tg(td, blkcg);
- if (tg) {
- rcu_read_unlock();
- return tg;
- }
-
- /*
- * Need to allocate a group. Allocation of group also needs allocation
- * of per cpu stats which in-turn takes a mutex() and can block. Hence
- * we need to drop rcu lock and queue_lock before we call alloc.
- */
- rcu_read_unlock();
- spin_unlock_irq(q->queue_lock);
-
- tg = throtl_alloc_tg(td);
-
- /* Group allocated and queue is still alive. take the lock */
- spin_lock_irq(q->queue_lock);
-
- /* Make sure @q is still alive */
- if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) {
- kfree(tg);
- return NULL;
- }
+ struct throtl_grp *tg = NULL;
/*
- * Initialize the new group. After sleeping, read the blkcg again.
+ * This is the common case when there are no blkio cgroups.
+ * Avoid lookup in this case
*/
- rcu_read_lock();
- blkcg = task_blkio_cgroup(current);
+ if (blkcg == &blkio_root_cgroup) {
+ tg = td->root_tg;
+ } else {
+ struct blkio_group *blkg;
- /*
- * If some other thread already allocated the group while we were
- * not holding queue lock, free up the group
- */
- __tg = throtl_find_tg(td, blkcg);
+ blkg = blkg_lookup_create(blkcg, q, BLKIO_POLICY_THROTL, false);
- if (__tg) {
- kfree(tg);
- rcu_read_unlock();
- return __tg;
+ /* if %NULL and @q is alive, fall back to root_tg */
+ if (!IS_ERR(blkg))
+ tg = blkg_to_tg(blkg);
+ else if (!blk_queue_dead(q))
+ tg = td->root_tg;
}
- /* Group allocation failed. Account the IO to root group */
- if (!tg) {
- tg = td->root_tg;
- return tg;
- }
-
- throtl_init_add_tg_lists(td, tg, blkcg);
- rcu_read_unlock();
return tg;
}
tg->bytes_disp[rw] += bio->bi_size;
tg->io_disp[rw]++;
- blkiocg_update_dispatch_stats(&tg->blkg, bio->bi_size, rw, sync);
+ blkiocg_update_dispatch_stats(tg_to_blkg(tg), bio->bi_size, rw, sync);
}
static void throtl_add_bio_tg(struct throtl_data *td, struct throtl_grp *tg,
td->nr_undestroyed_grps--;
}
-static void throtl_release_tgs(struct throtl_data *td)
+static bool throtl_release_tgs(struct throtl_data *td, bool release_root)
{
struct hlist_node *pos, *n;
struct throtl_grp *tg;
+ bool empty = true;
hlist_for_each_entry_safe(tg, pos, n, &td->tg_list, tg_node) {
+ /* skip root? */
+ if (!release_root && tg == td->root_tg)
+ continue;
+
/*
* If cgroup removal path got to blk_group first and removed
* it from cgroup list, then it will take care of destroying
* cfqg also.
*/
- if (!blkiocg_del_blkio_group(&tg->blkg))
+ if (!blkiocg_del_blkio_group(tg_to_blkg(tg)))
throtl_destroy_tg(td, tg);
+ else
+ empty = false;
}
+ return empty;
}
/*
* no new IO will come in this group. So get rid of this group as soon as
* any pending IO in the group is finished.
*
- * This function is called under rcu_read_lock(). key is the rcu protected
- * pointer. That means "key" is a valid throtl_data pointer as long as we are
- * rcu read lock.
+ * This function is called under rcu_read_lock(). @q is the rcu protected
+ * pointer. That means @q is a valid request_queue pointer as long as we
+ * are rcu read lock.
*
- * "key" was fetched from blkio_group under blkio_cgroup->lock. That means
+ * @q was fetched from blkio_group under blkio_cgroup->lock. That means
* it should not be NULL as even if queue was going away, cgroup deltion
* path got to it first.
*/
-void throtl_unlink_blkio_group(void *key, struct blkio_group *blkg)
+void throtl_unlink_blkio_group(struct request_queue *q,
+ struct blkio_group *blkg)
{
unsigned long flags;
- struct throtl_data *td = key;
- spin_lock_irqsave(td->queue->queue_lock, flags);
- throtl_destroy_tg(td, tg_of_blkg(blkg));
- spin_unlock_irqrestore(td->queue->queue_lock, flags);
+ spin_lock_irqsave(q->queue_lock, flags);
+ throtl_destroy_tg(q->td, blkg_to_tg(blkg));
+ spin_unlock_irqrestore(q->queue_lock, flags);
+}
+
+static bool throtl_clear_queue(struct request_queue *q)
+{
+ lockdep_assert_held(q->queue_lock);
+
+ /*
+ * Clear tgs but leave the root one alone. This is necessary
+ * because root_tg is expected to be persistent and safe because
+ * blk-throtl can never be disabled while @q is alive. This is a
+ * kludge to prepare for unified blkg. This whole function will be
+ * removed soon.
+ */
+ return throtl_release_tgs(q->td, false);
}
static void throtl_update_blkio_group_common(struct throtl_data *td,
}
/*
- * For all update functions, key should be a valid pointer because these
+ * For all update functions, @q should be a valid pointer because these
* update functions are called under blkcg_lock, that means, blkg is
- * valid and in turn key is valid. queue exit path can not race because
+ * valid and in turn @q is valid. queue exit path can not race because
* of blkcg_lock
*
* Can not take queue lock in update functions as queue lock under blkcg_lock
* is not allowed. Under other paths we take blkcg_lock under queue_lock.
*/
-static void throtl_update_blkio_group_read_bps(void *key,
+static void throtl_update_blkio_group_read_bps(struct request_queue *q,
struct blkio_group *blkg, u64 read_bps)
{
- struct throtl_data *td = key;
- struct throtl_grp *tg = tg_of_blkg(blkg);
+ struct throtl_grp *tg = blkg_to_tg(blkg);
tg->bps[READ] = read_bps;
- throtl_update_blkio_group_common(td, tg);
+ throtl_update_blkio_group_common(q->td, tg);
}
-static void throtl_update_blkio_group_write_bps(void *key,
+static void throtl_update_blkio_group_write_bps(struct request_queue *q,
struct blkio_group *blkg, u64 write_bps)
{
- struct throtl_data *td = key;
- struct throtl_grp *tg = tg_of_blkg(blkg);
+ struct throtl_grp *tg = blkg_to_tg(blkg);
tg->bps[WRITE] = write_bps;
- throtl_update_blkio_group_common(td, tg);
+ throtl_update_blkio_group_common(q->td, tg);
}
-static void throtl_update_blkio_group_read_iops(void *key,
+static void throtl_update_blkio_group_read_iops(struct request_queue *q,
struct blkio_group *blkg, unsigned int read_iops)
{
- struct throtl_data *td = key;
- struct throtl_grp *tg = tg_of_blkg(blkg);
+ struct throtl_grp *tg = blkg_to_tg(blkg);
tg->iops[READ] = read_iops;
- throtl_update_blkio_group_common(td, tg);
+ throtl_update_blkio_group_common(q->td, tg);
}
-static void throtl_update_blkio_group_write_iops(void *key,
+static void throtl_update_blkio_group_write_iops(struct request_queue *q,
struct blkio_group *blkg, unsigned int write_iops)
{
- struct throtl_data *td = key;
- struct throtl_grp *tg = tg_of_blkg(blkg);
+ struct throtl_grp *tg = blkg_to_tg(blkg);
tg->iops[WRITE] = write_iops;
- throtl_update_blkio_group_common(td, tg);
+ throtl_update_blkio_group_common(q->td, tg);
}
static void throtl_shutdown_wq(struct request_queue *q)
static struct blkio_policy_type blkio_policy_throtl = {
.ops = {
+ .blkio_init_group_fn = throtl_init_blkio_group,
+ .blkio_link_group_fn = throtl_link_blkio_group,
.blkio_unlink_group_fn = throtl_unlink_blkio_group,
+ .blkio_clear_queue_fn = throtl_clear_queue,
.blkio_update_group_read_bps_fn =
throtl_update_blkio_group_read_bps,
.blkio_update_group_write_bps_fn =
throtl_update_blkio_group_write_iops,
},
.plid = BLKIO_POLICY_THROTL,
+ .pdata_size = sizeof(struct throtl_grp),
};
bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
* basic fields like stats and io rates. If a group has no rules,
* just update the dispatch stats in lockless manner and return.
*/
-
rcu_read_lock();
blkcg = task_blkio_cgroup(current);
- tg = throtl_find_tg(td, blkcg);
+ tg = throtl_lookup_tg(td, blkcg);
if (tg) {
- throtl_tg_fill_dev_details(td, tg);
-
if (tg_no_rule_group(tg, rw)) {
- blkiocg_update_dispatch_stats(&tg->blkg, bio->bi_size,
- rw, rw_is_sync(bio->bi_rw));
- rcu_read_unlock();
- goto out;
+ blkiocg_update_dispatch_stats(tg_to_blkg(tg),
+ bio->bi_size, rw,
+ rw_is_sync(bio->bi_rw));
+ goto out_unlock_rcu;
}
}
- rcu_read_unlock();
/*
* Either group has not been allocated yet or it is not an unlimited
* IO group
*/
spin_lock_irq(q->queue_lock);
- tg = throtl_get_tg(td);
+ tg = throtl_lookup_create_tg(td, blkcg);
if (unlikely(!tg))
goto out_unlock;
out_unlock:
spin_unlock_irq(q->queue_lock);
+out_unlock_rcu:
+ rcu_read_unlock();
out:
return throttled;
}
int blk_throtl_init(struct request_queue *q)
{
struct throtl_data *td;
- struct throtl_grp *tg;
+ struct blkio_group *blkg;
td = kzalloc_node(sizeof(*td), GFP_KERNEL, q->node);
if (!td)
td->limits_changed = false;
INIT_DELAYED_WORK(&td->throtl_work, blk_throtl_work);
- /* alloc and Init root group. */
+ q->td = td;
td->queue = q;
- tg = throtl_alloc_tg(td);
- if (!tg) {
- kfree(td);
- return -ENOMEM;
- }
+ /* alloc and init root group. */
+ rcu_read_lock();
+ spin_lock_irq(q->queue_lock);
- td->root_tg = tg;
+ blkg = blkg_lookup_create(&blkio_root_cgroup, q, BLKIO_POLICY_THROTL,
+ true);
+ if (!IS_ERR(blkg))
+ td->root_tg = blkg_to_tg(blkg);
- rcu_read_lock();
- throtl_init_add_tg_lists(td, tg, &blkio_root_cgroup);
+ spin_unlock_irq(q->queue_lock);
rcu_read_unlock();
- /* Attach throtl data to request queue */
- q->td = td;
+ if (!td->root_tg) {
+ kfree(td);
+ return -ENOMEM;
+ }
return 0;
}
throtl_shutdown_wq(q);
spin_lock_irq(q->queue_lock);
- throtl_release_tgs(td);
+ throtl_release_tgs(td, true);
/* If there are other groups */
if (td->nr_undestroyed_grps > 0)
spin_unlock_irq(q->queue_lock);
/*
- * Wait for tg->blkg->key accessors to exit their grace periods.
+ * Wait for tg_to_blkg(tg)->q accessors to exit their grace periods.
* Do this wait only if there are other undestroyed groups out
* there (other than root group). This can happen if cgroup deletion
* path claimed the responsibility of cleaning up a group before
* it.
*/
throtl_shutdown_wq(q);
-}
-void blk_throtl_release(struct request_queue *q)
-{
kfree(q->td);
}
projects / linux-2.6-block.git / blobdiff