Commit f51b802c authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe

blkcg: use the usual get blkg path for root blkio_group

For root blkg, blk_throtl_init() was using throtl_alloc_tg()
explicitly and cfq_init_queue() was manually initializing embedded
cfqd->root_group, adding unnecessarily different code paths to blkg
handling.

Make both use the usual blkio_group get functions - throtl_get_tg()
and cfq_get_cfqg() - for the root blkio_group too.  Note that
blk_throtl_init() callsite is pushed downwards in
blk_alloc_queue_node() so that @q is sufficiently initialized for
throtl_get_tg().

This simplifies root blkg handling noticeably for cfq and will allow
further modularization of blkcg API.

-v2: Vivek pointed out that using cfq_get_cfqg() won't work if
     CONFIG_CFQ_GROUP_IOSCHED is disabled.  Fix it by factoring out
     initialization of base part of cfqg into cfq_init_cfqg_base() and
     alloc/init/free explicitly if !CONFIG_CFQ_GROUP_IOSCHED.
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 035d10b2
......@@ -540,9 +540,6 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
if (err)
goto fail_id;
if (blk_throtl_init(q))
goto fail_id;
setup_timer(&q->backing_dev_info.laptop_mode_wb_timer,
laptop_mode_timer_fn, (unsigned long) q);
setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q);
......@@ -565,6 +562,9 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
*/
q->queue_lock = &q->__queue_lock;
if (blk_throtl_init(q))
goto fail_id;
return q;
fail_id:
......
......@@ -1252,7 +1252,6 @@ void blk_throtl_drain(struct request_queue *q)
int blk_throtl_init(struct request_queue *q)
{
struct throtl_data *td;
struct throtl_grp *tg;
td = kzalloc_node(sizeof(*td), GFP_KERNEL, q->node);
if (!td)
......@@ -1265,19 +1264,20 @@ int blk_throtl_init(struct request_queue *q)
/* alloc and Init root group. */
td->queue = q;
tg = throtl_alloc_tg(td);
if (!tg) {
kfree(td);
return -ENOMEM;
}
rcu_read_lock();
spin_lock_irq(q->queue_lock);
td->root_tg = tg;
td->root_tg = throtl_get_tg(td, &blkio_root_cgroup);
rcu_read_lock();
throtl_init_add_tg_lists(td, tg, &blkio_root_cgroup);
spin_unlock_irq(q->queue_lock);
rcu_read_unlock();
if (!td->root_tg) {
kfree(td);
return -ENOMEM;
}
/* Attach throtl data to request queue */
q->td = td;
return 0;
......
......@@ -229,7 +229,7 @@ struct cfq_data {
struct request_queue *queue;
/* Root service tree for cfq_groups */
struct cfq_rb_root grp_service_tree;
struct cfq_group root_group;
struct cfq_group *root_group;
/*
* The priority currently being served
......@@ -1012,6 +1012,25 @@ static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
cfq_blkiocg_set_start_empty_time(&cfqg->blkg);
}
/**
* cfq_init_cfqg_base - initialize base part of a cfq_group
* @cfqg: cfq_group to initialize
*
* Initialize the base part which is used whether %CONFIG_CFQ_GROUP_IOSCHED
* is enabled or not.
*/
static void cfq_init_cfqg_base(struct cfq_group *cfqg)
{
struct cfq_rb_root *st;
int i, j;
for_each_cfqg_st(cfqg, i, j, st)
*st = CFQ_RB_ROOT;
RB_CLEAR_NODE(&cfqg->rb_node);
cfqg->ttime.last_end_request = jiffies;
}
#ifdef CONFIG_CFQ_GROUP_IOSCHED
static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg)
{
......@@ -1063,19 +1082,14 @@ static void cfq_init_add_cfqg_lists(struct cfq_data *cfqd,
*/
static struct cfq_group * cfq_alloc_cfqg(struct cfq_data *cfqd)
{
struct cfq_group *cfqg = NULL;
int i, j, ret;
struct cfq_rb_root *st;
struct cfq_group *cfqg;
int ret;
cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node);
if (!cfqg)
return NULL;
for_each_cfqg_st(cfqg, i, j, st)
*st = CFQ_RB_ROOT;
RB_CLEAR_NODE(&cfqg->rb_node);
cfqg->ttime.last_end_request = jiffies;
cfq_init_cfqg_base(cfqg);
/*
* Take the initial reference that will be released on destroy
......@@ -1106,7 +1120,7 @@ cfq_find_cfqg(struct cfq_data *cfqd, struct blkio_cgroup *blkcg)
* Avoid lookup in this case
*/
if (blkcg == &blkio_root_cgroup)
cfqg = &cfqd->root_group;
cfqg = cfqd->root_group;
else
cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, cfqd->queue,
BLKIO_POLICY_PROP));
......@@ -1166,7 +1180,7 @@ static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd,
}
if (!cfqg)
cfqg = &cfqd->root_group;
cfqg = cfqd->root_group;
cfq_init_add_cfqg_lists(cfqd, cfqg, blkcg);
return cfqg;
......@@ -1182,7 +1196,7 @@ static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
{
/* Currently, all async queues are mapped to root group */
if (!cfq_cfqq_sync(cfqq))
cfqg = &cfqq->cfqd->root_group;
cfqg = cfqq->cfqd->root_group;
cfqq->cfqg = cfqg;
/* cfqq reference on cfqg */
......@@ -1283,7 +1297,7 @@ static bool cfq_clear_queue(struct request_queue *q)
static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd,
struct blkio_cgroup *blkcg)
{
return &cfqd->root_group;
return cfqd->root_group;
}
static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
......@@ -3671,9 +3685,8 @@ static void cfq_exit_queue(struct elevator_queue *e)
if (wait)
synchronize_rcu();
#ifdef CONFIG_CFQ_GROUP_IOSCHED
/* Free up per cpu stats for root group */
free_percpu(cfqd->root_group.blkg.stats_cpu);
#ifndef CONFIG_CFQ_GROUP_IOSCHED
kfree(cfqd->root_group);
#endif
kfree(cfqd);
}
......@@ -3681,52 +3694,40 @@ static void cfq_exit_queue(struct elevator_queue *e)
static int cfq_init_queue(struct request_queue *q)
{
struct cfq_data *cfqd;
int i, j;
struct cfq_group *cfqg;
struct cfq_rb_root *st;
int i;
cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
if (!cfqd)
return -ENOMEM;
cfqd->queue = q;
q->elevator->elevator_data = cfqd;
/* Init root service tree */
cfqd->grp_service_tree = CFQ_RB_ROOT;
/* Init root group */
cfqg = &cfqd->root_group;
for_each_cfqg_st(cfqg, i, j, st)
*st = CFQ_RB_ROOT;
RB_CLEAR_NODE(&cfqg->rb_node);
/* Give preference to root group over other groups */
cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT;
/* Init root group and prefer root group over other groups by default */
#ifdef CONFIG_CFQ_GROUP_IOSCHED
/*
* Set root group reference to 2. One reference will be dropped when
* all groups on cfqd->cfqg_list are being deleted during queue exit.
* Other reference will remain there as we don't want to delete this
* group as it is statically allocated and gets destroyed when
* throtl_data goes away.
*/
cfqg->ref = 2;
rcu_read_lock();
spin_lock_irq(q->queue_lock);
if (blkio_alloc_blkg_stats(&cfqg->blkg)) {
kfree(cfqg);
cfqd->root_group = cfq_get_cfqg(cfqd, &blkio_root_cgroup);
spin_unlock_irq(q->queue_lock);
rcu_read_unlock();
#else
cfqd->root_group = kzalloc_node(sizeof(*cfqd->root_group),
GFP_KERNEL, cfqd->queue->node);
if (cfqd->root_group)
cfq_init_cfqg_base(cfqd->root_group);
#endif
if (!cfqd->root_group) {
kfree(cfqd);
return -ENOMEM;
}
rcu_read_lock();
cfqd->root_group->weight = 2*BLKIO_WEIGHT_DEFAULT;
cfq_blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg,
cfqd->queue, 0);
rcu_read_unlock();
cfqd->nr_blkcg_linked_grps++;
/* Add group on cfqd->cfqg_list */
hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
#endif
/*
* Not strictly needed (since RB_ROOT just clears the node and we
* zeroed cfqd on alloc), but better be safe in case someone decides
......@@ -3738,14 +3739,14 @@ static int cfq_init_queue(struct request_queue *q)
/*
* Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
* Grab a permanent reference to it, so that the normal code flow
* will not attempt to free it.
* will not attempt to free it. oom_cfqq is linked to root_group
* but shouldn't hold a reference as it'll never be unlinked. Lose
* the reference from linking right away.
*/
cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
cfqd->oom_cfqq.ref++;
cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group);
cfqd->queue = q;
q->elevator->elevator_data = cfqd;
cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, cfqd->root_group);
cfq_put_cfqg(cfqd->root_group);
init_timer(&cfqd->idle_slice_timer);
cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
......
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