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-rw-r--r--block/blk-cgroup.c78
1 files changed, 62 insertions, 16 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index c2033a232a44..1c16694ae145 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -307,11 +307,28 @@ struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
}
}
+static void blkg_pd_offline(struct blkcg_gq *blkg)
+{
+ int i;
+
+ lockdep_assert_held(blkg->q->queue_lock);
+ lockdep_assert_held(&blkg->blkcg->lock);
+
+ for (i = 0; i < BLKCG_MAX_POLS; i++) {
+ struct blkcg_policy *pol = blkcg_policy[i];
+
+ if (blkg->pd[i] && !blkg->pd[i]->offline &&
+ pol->pd_offline_fn) {
+ pol->pd_offline_fn(blkg->pd[i]);
+ blkg->pd[i]->offline = true;
+ }
+ }
+}
+
static void blkg_destroy(struct blkcg_gq *blkg)
{
struct blkcg *blkcg = blkg->blkcg;
struct blkcg_gq *parent = blkg->parent;
- int i;
lockdep_assert_held(blkg->q->queue_lock);
lockdep_assert_held(&blkcg->lock);
@@ -320,13 +337,6 @@ static void blkg_destroy(struct blkcg_gq *blkg)
WARN_ON_ONCE(list_empty(&blkg->q_node));
WARN_ON_ONCE(hlist_unhashed(&blkg->blkcg_node));
- for (i = 0; i < BLKCG_MAX_POLS; i++) {
- struct blkcg_policy *pol = blkcg_policy[i];
-
- if (blkg->pd[i] && pol->pd_offline_fn)
- pol->pd_offline_fn(blkg->pd[i]);
- }
-
if (parent) {
blkg_rwstat_add_aux(&parent->stat_bytes, &blkg->stat_bytes);
blkg_rwstat_add_aux(&parent->stat_ios, &blkg->stat_ios);
@@ -369,6 +379,7 @@ static void blkg_destroy_all(struct request_queue *q)
struct blkcg *blkcg = blkg->blkcg;
spin_lock(&blkcg->lock);
+ blkg_pd_offline(blkg);
blkg_destroy(blkg);
spin_unlock(&blkcg->lock);
}
@@ -995,25 +1006,25 @@ static struct cftype blkcg_legacy_files[] = {
* @css: css of interest
*
* This function is called when @css is about to go away and responsible
- * for shooting down all blkgs associated with @css. blkgs should be
- * removed while holding both q and blkcg locks. As blkcg lock is nested
- * inside q lock, this function performs reverse double lock dancing.
+ * for offlining all blkgs pd and killing all wbs associated with @css.
+ * blkgs pd offline should be done while holding both q and blkcg locks.
+ * As blkcg lock is nested inside q lock, this function performs reverse
+ * double lock dancing.
*
* This is the blkcg counterpart of ioc_release_fn().
*/
static void blkcg_css_offline(struct cgroup_subsys_state *css)
{
struct blkcg *blkcg = css_to_blkcg(css);
+ struct blkcg_gq *blkg;
spin_lock_irq(&blkcg->lock);
- while (!hlist_empty(&blkcg->blkg_list)) {
- struct blkcg_gq *blkg = hlist_entry(blkcg->blkg_list.first,
- struct blkcg_gq, blkcg_node);
+ hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
struct request_queue *q = blkg->q;
if (spin_trylock(q->queue_lock)) {
- blkg_destroy(blkg);
+ blkg_pd_offline(blkg);
spin_unlock(q->queue_lock);
} else {
spin_unlock_irq(&blkcg->lock);
@@ -1027,11 +1038,43 @@ static void blkcg_css_offline(struct cgroup_subsys_state *css)
wb_blkcg_offline(blkcg);
}
+/**
+ * blkcg_destroy_all_blkgs - destroy all blkgs associated with a blkcg
+ * @blkcg: blkcg of interest
+ *
+ * This function is called when blkcg css is about to free and responsible for
+ * destroying all blkgs associated with @blkcg.
+ * blkgs should be removed while holding both q and blkcg locks. As blkcg lock
+ * is nested inside q lock, this function performs reverse double lock dancing.
+ */
+static void blkcg_destroy_all_blkgs(struct blkcg *blkcg)
+{
+ spin_lock_irq(&blkcg->lock);
+ while (!hlist_empty(&blkcg->blkg_list)) {
+ struct blkcg_gq *blkg = hlist_entry(blkcg->blkg_list.first,
+ struct blkcg_gq,
+ blkcg_node);
+ struct request_queue *q = blkg->q;
+
+ if (spin_trylock(q->queue_lock)) {
+ blkg_destroy(blkg);
+ spin_unlock(q->queue_lock);
+ } else {
+ spin_unlock_irq(&blkcg->lock);
+ cpu_relax();
+ spin_lock_irq(&blkcg->lock);
+ }
+ }
+ spin_unlock_irq(&blkcg->lock);
+}
+
static void blkcg_css_free(struct cgroup_subsys_state *css)
{
struct blkcg *blkcg = css_to_blkcg(css);
int i;
+ blkcg_destroy_all_blkgs(blkcg);
+
mutex_lock(&blkcg_pol_mutex);
list_del(&blkcg->all_blkcgs_node);
@@ -1371,8 +1414,11 @@ void blkcg_deactivate_policy(struct request_queue *q,
spin_lock(&blkg->blkcg->lock);
if (blkg->pd[pol->plid]) {
- if (pol->pd_offline_fn)
+ if (!blkg->pd[pol->plid]->offline &&
+ pol->pd_offline_fn) {
pol->pd_offline_fn(blkg->pd[pol->plid]);
+ blkg->pd[pol->plid]->offline = true;
+ }
pol->pd_free_fn(blkg->pd[pol->plid]);
blkg->pd[pol->plid] = NULL;
}