kfree(blkg);
}
-static void __blkg_release(struct rcu_head *rcu)
-{
- struct blkcg_gq *blkg = container_of(rcu, struct blkcg_gq, rcu_head);
-
- percpu_ref_exit(&blkg->refcnt);
-
- /* release the blkcg and parent blkg refs this blkg has been holding */
- css_put(&blkg->blkcg->css);
- if (blkg->parent)
- blkg_put(blkg->parent);
-
- wb_congested_put(blkg->wb_congested);
-
- blkg_free(blkg);
-}
-
-/*
- * A group is RCU protected, but having an rcu lock does not mean that one
- * can access all the fields of blkg and assume these are valid. For
- * example, don't try to follow throtl_data and request queue links.
- *
- * Having a reference to blkg under an rcu allows accesses to only values
- * local to groups like group stats and group rate limits.
- */
-static void blkg_release(struct percpu_ref *ref)
-{
- struct blkcg_gq *blkg = container_of(ref, struct blkcg_gq, refcnt);
-
- call_rcu(&blkg->rcu_head, __blkg_release);
-}
-
/**
* blkg_alloc - allocate a blkg
* @blkcg: block cgroup the new blkg is associated with
blkg->q = q;
INIT_LIST_HEAD(&blkg->q_node);
blkg->blkcg = blkcg;
+ atomic_set(&blkg->refcnt, 1);
/* root blkg uses @q->root_rl, init rl only for !root blkgs */
if (blkcg != &blkcg_root) {
blkg_get(blkg->parent);
}
- ret = percpu_ref_init(&blkg->refcnt, blkg_release, 0,
- GFP_NOWAIT | __GFP_NOWARN);
- if (ret)
- goto err_cancel_ref;
-
/* invoke per-policy init */
for (i = 0; i < BLKCG_MAX_POLS; i++) {
struct blkcg_policy *pol = blkcg_policy[i];
blkg_put(blkg);
return ERR_PTR(ret);
-err_cancel_ref:
- percpu_ref_exit(&blkg->refcnt);
err_put_congested:
wb_congested_put(wb_congested);
err_put_css:
}
/**
- * __blkg_lookup_create - lookup blkg, try to create one if not there
+ * blkg_lookup_create - lookup blkg, try to create one if not there
* @blkcg: blkcg of interest
* @q: request_queue of interest
*
* that all non-root blkg's have access to the parent blkg. This function
* should be called under RCU read lock and @q->queue_lock.
*
- * Returns the blkg or the closest blkg if blkg_create fails as it walks
- * down from root.
+ * Returns pointer to the looked up or created blkg on success, ERR_PTR()
+ * value on error. If @q is dead, returns ERR_PTR(-EINVAL). If @q is not
+ * dead and bypassing, returns ERR_PTR(-EBUSY).
*/
-struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg,
- struct request_queue *q)
+struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
+ struct request_queue *q)
{
struct blkcg_gq *blkg;
* we shouldn't allow anything to go through for a bypassing queue.
*/
if (unlikely(blk_queue_bypass(q)))
- return q->root_blkg;
+ return ERR_PTR(blk_queue_dying(q) ? -ENODEV : -EBUSY);
blkg = __blkg_lookup(blkcg, q, true);
if (blkg)
/*
* Create blkgs walking down from blkcg_root to @blkcg, so that all
- * non-root blkgs have access to their parents. Returns the closest
- * blkg to the intended blkg should blkg_create() fail.
+ * non-root blkgs have access to their parents.
*/
while (true) {
struct blkcg *pos = blkcg;
struct blkcg *parent = blkcg_parent(blkcg);
- struct blkcg_gq *ret_blkg = q->root_blkg;
-
- while (parent) {
- blkg = __blkg_lookup(parent, q, false);
- if (blkg) {
- /* remember closest blkg */
- ret_blkg = blkg;
- break;
- }
+
+ while (parent && !__blkg_lookup(parent, q, false)) {
pos = parent;
parent = blkcg_parent(parent);
}
blkg = blkg_create(pos, q, NULL);
- if (IS_ERR(blkg))
- return ret_blkg;
- if (pos == blkcg)
+ if (pos == blkcg || IS_ERR(blkg))
return blkg;
}
}
-/**
- * blkg_lookup_create - find or create a blkg
- * @blkcg: target block cgroup
- * @q: target request_queue
- *
- * This looks up or creates the blkg representing the unique pair
- * of the blkcg and the request_queue.
- */
-struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
- struct request_queue *q)
-{
- struct blkcg_gq *blkg = blkg_lookup(blkcg, q);
- unsigned long flags;
-
- if (unlikely(!blkg)) {
- spin_lock_irqsave(q->queue_lock, flags);
-
- blkg = __blkg_lookup_create(blkcg, q);
-
- spin_unlock_irqrestore(q->queue_lock, flags);
- }
-
- return blkg;
-}
-
static void blkg_destroy(struct blkcg_gq *blkg)
{
struct blkcg *blkcg = blkg->blkcg;
* Put the reference taken at the time of creation so that when all
* queues are gone, group can be destroyed.
*/
- percpu_ref_kill(&blkg->refcnt);
+ blkg_put(blkg);
}
/**
q->root_rl.blkg = NULL;
}
+/*
+ * A group is RCU protected, but having an rcu lock does not mean that one
+ * can access all the fields of blkg and assume these are valid. For
+ * example, don't try to follow throtl_data and request queue links.
+ *
+ * Having a reference to blkg under an rcu allows accesses to only values
+ * local to groups like group stats and group rate limits.
+ */
+void __blkg_release_rcu(struct rcu_head *rcu_head)
+{
+ struct blkcg_gq *blkg = container_of(rcu_head, struct blkcg_gq, rcu_head);
+
+ /* release the blkcg and parent blkg refs this blkg has been holding */
+ css_put(&blkg->blkcg->css);
+ if (blkg->parent)
+ blkg_put(blkg->parent);
+
+ wb_congested_put(blkg->wb_congested);
+
+ blkg_free(blkg);
+}
+EXPORT_SYMBOL_GPL(__blkg_release_rcu);
+
/*
* The next function used by blk_queue_for_each_rl(). It's a bit tricky
* because the root blkg uses @q->root_rl instead of its own rl.
blkg = blkg_lookup(blkcg, q);
if (!blkg)
goto out;
- if (!blkg_tryget(blkg))
+ blkg = blkg_try_get(blkg);
+ if (!blkg)
goto out;
rcu_read_unlock();
git.samba.org / sfrench / cifs-2.6.git / blobdiff