Revert "blkcg: allocate struct blkcg_gq outside request queue spinlock"
I inadvertently applied the v5 version of this patch, whereas
the agreed upon version was v5. Revert this one so we can apply
the right one.
This reverts commit 7fc6b87a9ff537e7df32b1278118ce9c5bcd6788.
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index bdf87f0..bbe7ee0 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -165,18 +165,16 @@ struct blkcg_gq *blkg_lookup_slowpath(struct blkcg *blkcg,
EXPORT_SYMBOL_GPL(blkg_lookup_slowpath);
/*
- * If gfp mask allows blocking, this function temporarily drops rcu and queue
- * locks to allocate memory.
+ * If @new_blkg is %NULL, this function tries to allocate a new one as
+ * necessary using %GFP_NOWAIT. @new_blkg is always consumed on return.
*/
static struct blkcg_gq *blkg_create(struct blkcg *blkcg,
- struct request_queue *q, gfp_t gfp,
- const struct blkcg_policy *pol)
+ struct request_queue *q,
+ struct blkcg_gq *new_blkg)
{
- struct blkcg_gq *blkg = NULL;
+ struct blkcg_gq *blkg;
struct bdi_writeback_congested *wb_congested;
int i, ret;
- const bool drop_locks = gfpflags_allow_blocking(gfp);
- bool preloaded = false;
WARN_ON_ONCE(!rcu_read_lock_held());
lockdep_assert_held(q->queue_lock);
@@ -187,53 +185,31 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg,
goto err_free_blkg;
}
- if (drop_locks) {
- spin_unlock_irq(q->queue_lock);
- rcu_read_unlock();
- }
-
wb_congested = wb_congested_get_create(q->backing_dev_info,
- blkcg->css.id, gfp);
- blkg = blkg_alloc(blkcg, q, gfp);
-
- if (drop_locks) {
- preloaded = !radix_tree_preload(gfp);
- rcu_read_lock();
- spin_lock_irq(q->queue_lock);
- }
-
- if (unlikely(!wb_congested || !blkg)) {
+ blkcg->css.id,
+ GFP_NOWAIT | __GFP_NOWARN);
+ if (!wb_congested) {
ret = -ENOMEM;
- goto err_put;
+ goto err_put_css;
}
+ /* allocate */
+ if (!new_blkg) {
+ new_blkg = blkg_alloc(blkcg, q, GFP_NOWAIT | __GFP_NOWARN);
+ if (unlikely(!new_blkg)) {
+ ret = -ENOMEM;
+ goto err_put_congested;
+ }
+ }
+ blkg = new_blkg;
blkg->wb_congested = wb_congested;
- if (pol) {
- WARN_ON(!drop_locks);
-
- if (!blkcg_policy_enabled(q, pol)) {
- ret = -EOPNOTSUPP;
- goto err_put;
- }
-
- /*
- * This could be the first entry point of blkcg implementation
- * and we shouldn't allow anything to go through for a bypassing
- * queue.
- */
- if (unlikely(blk_queue_bypass(q))) {
- ret = blk_queue_dying(q) ? -ENODEV : -EBUSY;
- goto err_put;
- }
- }
-
/* link parent */
if (blkcg_parent(blkcg)) {
blkg->parent = __blkg_lookup(blkcg_parent(blkcg), q, false);
if (WARN_ON_ONCE(!blkg->parent)) {
ret = -ENODEV;
- goto err_put;
+ goto err_put_congested;
}
blkg_get(blkg->parent);
}
@@ -260,9 +236,6 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg,
pol->pd_online_fn(blkg->pd[i]);
}
}
-
- if (preloaded)
- radix_tree_preload_end();
blkg->online = true;
spin_unlock(&blkcg->lock);
@@ -273,45 +246,44 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg,
blkg_put(blkg);
return ERR_PTR(ret);
-err_put:
- if (preloaded)
- radix_tree_preload_end();
- if (wb_congested)
- wb_congested_put(wb_congested);
+err_put_congested:
+ wb_congested_put(wb_congested);
+err_put_css:
css_put(&blkcg->css);
err_free_blkg:
- blkg_free(blkg);
+ blkg_free(new_blkg);
return ERR_PTR(ret);
}
/**
- * __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
- * @gfp: gfp mask
- * @pol: blkcg policy (optional)
*
* Lookup blkg for the @blkcg - @q pair. If it doesn't exist, try to
* create one. blkg creation is performed recursively from blkcg_root such
* 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.
*
- * When gfp mask allows blocking, rcu and queue locks may be dropped for
- * allocating memory. In this case, the locks will be reacquired on return.
- *
* 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, gfp_t gfp,
- const struct blkcg_policy *pol)
+struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
+ struct request_queue *q)
{
struct blkcg_gq *blkg;
WARN_ON_ONCE(!rcu_read_lock_held());
lockdep_assert_held(q->queue_lock);
+ /*
+ * This could be the first entry point of blkcg implementation and
+ * we shouldn't allow anything to go through for a bypassing queue.
+ */
+ if (unlikely(blk_queue_bypass(q)))
+ return ERR_PTR(blk_queue_dying(q) ? -ENODEV : -EBUSY);
+
blkg = __blkg_lookup(blkcg, q, true);
if (blkg)
return blkg;
@@ -329,35 +301,12 @@ struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg,
parent = blkcg_parent(parent);
}
- blkg = blkg_create(pos, q, gfp, pol);
+ blkg = blkg_create(pos, q, NULL);
if (pos == blkcg || IS_ERR(blkg))
return blkg;
}
}
-/**
- * blkg_lookup_create - lookup blkg, try to create one if not there
- *
- * Performs an initial queue bypass check and then passes control to
- * __blkg_lookup_create().
- */
-struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
- struct request_queue *q, gfp_t gfp,
- const struct blkcg_policy *pol)
-{
- WARN_ON_ONCE(!rcu_read_lock_held());
- lockdep_assert_held(q->queue_lock);
-
- /*
- * This could be the first entry point of blkcg implementation and
- * we shouldn't allow anything to go through for a bypassing queue.
- */
- if (unlikely(blk_queue_bypass(q)))
- return ERR_PTR(blk_queue_dying(q) ? -ENODEV : -EBUSY);
-
- return __blkg_lookup_create(blkcg, q, gfp, pol);
-}
-
static void blkg_destroy(struct blkcg_gq *blkg)
{
struct blkcg *blkcg = blkg->blkcg;
@@ -868,7 +817,7 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
spin_lock_irq(disk->queue->queue_lock);
if (blkcg_policy_enabled(disk->queue, pol))
- blkg = blkg_lookup_create(blkcg, disk->queue, GFP_KERNEL, pol);
+ blkg = blkg_lookup_create(blkcg, disk->queue);
else
blkg = ERR_PTR(-EOPNOTSUPP);
@@ -1107,15 +1056,30 @@ blkcg_css_alloc(struct cgroup_subsys_state *parent_css)
*/
int blkcg_init_queue(struct request_queue *q)
{
- struct blkcg_gq *blkg;
+ 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);
+
+ /*
+ * Make sure the root blkg exists and count the existing blkgs. As
+ * @q is bypassing at this point, blkg_lookup_create() can't be
+ * used. Open code insertion.
+ */
rcu_read_lock();
spin_lock_irq(q->queue_lock);
- blkg = __blkg_lookup_create(&blkcg_root, q, GFP_KERNEL, NULL);
+ blkg = blkg_create(&blkcg_root, q, new_blkg);
spin_unlock_irq(q->queue_lock);
rcu_read_unlock();
+ if (preloaded)
+ radix_tree_preload_end();
+
if (IS_ERR(blkg))
return PTR_ERR(blkg);
