diff options
| -rw-r--r-- | block/blk-cgroup.c | 52 | ||||
| -rw-r--r-- | block/blk-cgroup.h | 6 |
2 files changed, 50 insertions, 8 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 30a7a9c58b38..02cf6335e9bd 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -142,11 +142,21 @@ static struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg, struct request_queue *q) { struct blkcg_gq *blkg; - struct hlist_node *n; - hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) - if (blkg->q == q) - return blkg; + blkg = rcu_dereference(blkcg->blkg_hint); + if (blkg && blkg->q == q) + return blkg; + + /* + * Hint didn't match. Look up from the radix tree. Note that we + * may not be holding queue_lock and thus are not sure whether + * @blkg from blkg_tree has already been removed or not, so we + * can't update hint to the lookup result. Leave it to the caller. + */ + blkg = radix_tree_lookup(&blkcg->blkg_tree, q->id); + if (blkg && blkg->q == q) + return blkg; + return NULL; } @@ -179,9 +189,12 @@ static struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg, WARN_ON_ONCE(!rcu_read_lock_held()); lockdep_assert_held(q->queue_lock); + /* lookup and update hint on success, see __blkg_lookup() for details */ blkg = __blkg_lookup(blkcg, q); - if (blkg) + if (blkg) { + rcu_assign_pointer(blkcg->blkg_hint, blkg); return blkg; + } /* blkg holds a reference to blkcg */ if (!css_tryget(&blkcg->css)) @@ -194,12 +207,24 @@ static struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg, goto err_put; /* insert */ + ret = radix_tree_preload(GFP_ATOMIC); + if (ret) + goto err_free; + spin_lock(&blkcg->lock); - hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list); - list_add(&blkg->q_node, &q->blkg_list); + ret = radix_tree_insert(&blkcg->blkg_tree, q->id, blkg); + if (likely(!ret)) { + hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list); + list_add(&blkg->q_node, &q->blkg_list); + } spin_unlock(&blkcg->lock); - return blkg; + radix_tree_preload_end(); + + if (!ret) + return blkg; +err_free: + blkg_free(blkg); err_put: css_put(&blkcg->css); return ERR_PTR(ret); @@ -229,10 +254,20 @@ static void blkg_destroy(struct blkcg_gq *blkg) /* Something wrong if we are trying to remove same group twice */ WARN_ON_ONCE(list_empty(&blkg->q_node)); WARN_ON_ONCE(hlist_unhashed(&blkg->blkcg_node)); + + radix_tree_delete(&blkcg->blkg_tree, blkg->q->id); list_del_init(&blkg->q_node); hlist_del_init_rcu(&blkg->blkcg_node); /* + * Both setting lookup hint to and clearing it from @blkg are done + * under queue_lock. If it's not pointing to @blkg now, it never + * will. Hint assignment itself can race safely. + */ + if (rcu_dereference_raw(blkcg->blkg_hint) == blkg) + rcu_assign_pointer(blkcg->blkg_hint, NULL); + + /* * Put the reference taken at the time of creation so that when all * queues are gone, group can be destroyed. */ @@ -593,6 +628,7 @@ static struct cgroup_subsys_state *blkcg_create(struct cgroup *cgroup) blkcg->id = atomic64_inc_return(&id_seq); /* root is 0, start from 1 */ done: spin_lock_init(&blkcg->lock); + INIT_RADIX_TREE(&blkcg->blkg_tree, GFP_ATOMIC); INIT_HLIST_HEAD(&blkcg->blkg_list); return &blkcg->css; diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h index 44cb9086ed42..8ac457ce7783 100644 --- a/block/blk-cgroup.h +++ b/block/blk-cgroup.h @@ -16,6 +16,7 @@ #include <linux/cgroup.h> #include <linux/u64_stats_sync.h> #include <linux/seq_file.h> +#include <linux/radix-tree.h> /* Max limits for throttle policy */ #define THROTL_IOPS_MAX UINT_MAX @@ -37,9 +38,14 @@ enum blkg_rwstat_type { BLKG_RWSTAT_TOTAL = BLKG_RWSTAT_NR, }; +struct blkcg_gq; + struct blkcg { struct cgroup_subsys_state css; spinlock_t lock; + + struct radix_tree_root blkg_tree; + struct blkcg_gq *blkg_hint; struct hlist_head blkg_list; /* for policies to test whether associated blkcg has changed */ |