From: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
This call to radix_tree_preload is awkward. At the point of allocation,
we're under not only a local lock, but also under the queue lock. So we
can't back out, drop the lock and retry the allocation. Replace this
preload call with a call to xa_reserve() which will ensure the memory is
allocated.
Signed-off-by: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
---
block/bfq-cgroup.c | 4 ++--
block/blk-cgroup.c | 52 ++++++++++++++++++++++------------------------
block/cfq-iosched.c | 4 ++--
include/linux/blk-cgroup.h | 5 ++---
4 files changed, 31 insertions(+), 34 deletions(-)
diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
index da1525ec4c87..0648aaa6498b 100644
--- a/block/bfq-cgroup.c
+++ b/block/bfq-cgroup.c
@@ -860,7 +860,7 @@ static int bfq_io_set_weight_legacy(struct cgroup_subsys_state *css,
return ret;
ret = 0;
- spin_lock_irq(&blkcg->lock);
+ xa_lock_irq(&blkcg->blkg_array);
bfqgd->weight = (unsigned short)val;
hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
struct bfq_group *bfqg = blkg_to_bfqg(blkg);
@@ -894,7 +894,7 @@ static int bfq_io_set_weight_legacy(struct cgroup_subsys_state *css,
bfqg->entity.prio_changed = 1;
}
}
- spin_unlock_irq(&blkcg->lock);
+ xa_unlock_irq(&blkcg->blkg_array);
return ret;
}
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 4117524ca45b..37962d52f1a8 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -146,12 +146,12 @@ struct blkcg_gq *blkg_lookup_slowpath(struct blkcg *blkcg,
struct blkcg_gq *blkg;
/*
- * Hint didn't match. Look up from the radix tree. Note that the
+ * Hint didn't match. Fetch from the xarray. Note that the
* hint can only be updated under queue_lock as otherwise @blkg
- * could have already been removed from blkg_tree. The caller is
+ * could have already been removed from blkg_array. The caller is
* responsible for grabbing queue_lock if @update_hint.
*/
- blkg = radix_tree_lookup(&blkcg->blkg_tree, q->id);
+ blkg = xa_load(&blkcg->blkg_array, q->id);
if (blkg && blkg->q == q) {
if (update_hint) {
lockdep_assert_held(q->queue_lock);
@@ -223,8 +223,8 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg,
}
/* insert */
- spin_lock(&blkcg->lock);
- ret = radix_tree_insert(&blkcg->blkg_tree, q->id, blkg);
+ xa_lock(&blkcg->blkg_array);
+ ret = xa_err(__xa_store(&blkcg->blkg_array, q->id, blkg, GFP_NOWAIT));
if (likely(!ret)) {
hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list);
list_add(&blkg->q_node, &q->blkg_list);
@@ -237,7 +237,7 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg,
}
}
blkg->online = true;
- spin_unlock(&blkcg->lock);
+ xa_unlock(&blkcg->blkg_array);
if (!ret)
return blkg;
@@ -314,7 +314,7 @@ static void blkg_destroy(struct blkcg_gq *blkg)
int i;
lockdep_assert_held(blkg->q->queue_lock);
- lockdep_assert_held(&blkcg->lock);
+ lockdep_assert_held(&blkcg->blkg_array.xa_lock);
/* Something wrong if we are trying to remove same group twice */
WARN_ON_ONCE(list_empty(&blkg->q_node));
@@ -334,7 +334,7 @@ static void blkg_destroy(struct blkcg_gq *blkg)
blkg->online = false;
- radix_tree_delete(&blkcg->blkg_tree, blkg->q->id);
+ xa_erase(&blkcg->blkg_array, blkg->q->id);
list_del_init(&blkg->q_node);
hlist_del_init_rcu(&blkg->blkcg_node);
@@ -368,9 +368,9 @@ static void blkg_destroy_all(struct request_queue *q)
list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) {
struct blkcg *blkcg = blkg->blkcg;
- spin_lock(&blkcg->lock);
+ xa_lock(&blkcg->blkg_array);
blkg_destroy(blkg);
- spin_unlock(&blkcg->lock);
+ xa_unlock(&blkcg->blkg_array);
}
q->root_blkg = NULL;
@@ -443,7 +443,7 @@ static int blkcg_reset_stats(struct cgroup_subsys_state *css,
int i;
mutex_lock(&blkcg_pol_mutex);
- spin_lock_irq(&blkcg->lock);
+ xa_lock_irq(&blkcg->blkg_array);
/*
* Note that stat reset is racy - it doesn't synchronize against
@@ -462,7 +462,7 @@ static int blkcg_reset_stats(struct cgroup_subsys_state *css,
}
}
- spin_unlock_irq(&blkcg->lock);
+ xa_unlock_irq(&blkcg->blkg_array);
mutex_unlock(&blkcg_pol_mutex);
return 0;
}
@@ -1012,7 +1012,7 @@ static void blkcg_css_offline(struct cgroup_subsys_state *css)
{
struct blkcg *blkcg = css_to_blkcg(css);
- spin_lock_irq(&blkcg->lock);
+ xa_lock_irq(&blkcg->blkg_array);
while (!hlist_empty(&blkcg->blkg_list)) {
struct blkcg_gq *blkg = hlist_entry(blkcg->blkg_list.first,
@@ -1023,13 +1023,13 @@ static void blkcg_css_offline(struct cgroup_subsys_state *css)
blkg_destroy(blkg);
spin_unlock(q->queue_lock);
} else {
- spin_unlock_irq(&blkcg->lock);
+ xa_unlock_irq(&blkcg->blkg_array);
cpu_relax();
- spin_lock_irq(&blkcg->lock);
+ xa_lock_irq(&blkcg->blkg_array);
}
}
- spin_unlock_irq(&blkcg->lock);
+ xa_unlock_irq(&blkcg->blkg_array);
wb_blkcg_offline(blkcg);
}
@@ -1096,8 +1096,7 @@ blkcg_css_alloc(struct cgroup_subsys_state *parent_css)
pol->cpd_init_fn(cpd);
}
- spin_lock_init(&blkcg->lock);
- INIT_RADIX_TREE(&blkcg->blkg_tree, GFP_NOWAIT | __GFP_NOWARN);
+ xa_init_flags(&blkcg->blkg_array, XA_FLAGS_LOCK_IRQ);
INIT_HLIST_HEAD(&blkcg->blkg_list);
#ifdef CONFIG_CGROUP_WRITEBACK
INIT_LIST_HEAD(&blkcg->cgwb_list);
@@ -1132,14 +1131,14 @@ blkcg_css_alloc(struct cgroup_subsys_state *parent_css)
int blkcg_init_queue(struct request_queue *q)
{
struct blkcg_gq *new_blkg, *blkg;
- bool preloaded;
int ret;
new_blkg = blkg_alloc(&blkcg_root, q, GFP_KERNEL);
if (!new_blkg)
return -ENOMEM;
- preloaded = !radix_tree_preload(GFP_KERNEL);
+ if (xa_reserve(&blkcg_root.blkg_array, q->id, GFP_KERNEL))
+ return -ENOMEM;
/*
* Make sure the root blkg exists and count the existing blkgs. As
@@ -1152,11 +1151,10 @@ int blkcg_init_queue(struct request_queue *q)
spin_unlock_irq(q->queue_lock);
rcu_read_unlock();
- if (preloaded)
- radix_tree_preload_end();
-
- if (IS_ERR(blkg))
+ if (IS_ERR(blkg)) {
+ xa_erase(&blkcg_root.blkg_array, q->id);
return PTR_ERR(blkg);
+ }
q->root_blkg = blkg;
q->root_rl.blkg = blkg;
@@ -1374,8 +1372,8 @@ void blkcg_deactivate_policy(struct request_queue *q,
__clear_bit(pol->plid, q->blkcg_pols);
list_for_each_entry(blkg, &q->blkg_list, q_node) {
- /* grab blkcg lock too while removing @pd from @blkg */
- spin_lock(&blkg->blkcg->lock);
+ /* grab xa_lock too while removing @pd from @blkg */
+ xa_lock(&blkg->blkcg->blkg_array);
if (blkg->pd[pol->plid]) {
if (pol->pd_offline_fn)
@@ -1384,7 +1382,7 @@ void blkcg_deactivate_policy(struct request_queue *q,
blkg->pd[pol->plid] = NULL;
}
- spin_unlock(&blkg->blkcg->lock);
+ xa_unlock(&blkg->blkcg->blkg_array);
}
spin_unlock_irq(q->queue_lock);
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 9f342ef1ad42..a51bef7af8df 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1827,7 +1827,7 @@ static int __cfq_set_weight(struct cgroup_subsys_state *css, u64 val,
if (val < min || val > max)
return -ERANGE;
- spin_lock_irq(&blkcg->lock);
+ xa_lock_irq(&blkcg->blkg_array);
cfqgd = blkcg_to_cfqgd(blkcg);
if (!cfqgd) {
ret = -EINVAL;
@@ -1859,7 +1859,7 @@ static int __cfq_set_weight(struct cgroup_subsys_state *css, u64 val,
}
out:
- spin_unlock_irq(&blkcg->lock);
+ xa_unlock_irq(&blkcg->blkg_array);
return ret;
}
diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h
index e9825ff57b15..6278c49d3997 100644
--- a/include/linux/blk-cgroup.h
+++ b/include/linux/blk-cgroup.h
@@ -17,7 +17,7 @@
#include <linux/cgroup.h>
#include <linux/percpu_counter.h>
#include <linux/seq_file.h>
-#include <linux/radix-tree.h>
+#include <linux/xarray.h>
#include <linux/blkdev.h>
#include <linux/atomic.h>
#include <linux/kthread.h>
@@ -44,9 +44,8 @@ struct blkcg_gq;
struct blkcg {
struct cgroup_subsys_state css;
- spinlock_t lock;
- struct radix_tree_root blkg_tree;
+ struct xarray blkg_array;
struct blkcg_gq __rcu *blkg_hint;
struct hlist_head blkg_list;
--
2.15.1
--
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