blk-cgroup: remove blkg_lookup_check

The combinations of an error check with an ERR_PTR return and a lookup
with a NULL return leads to ugly handling of the return values in the
callers.  Just open coding the check and the lookup is much simpler.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Andreas Herrmann <aherrmann@suse.de>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220921180501.1539876-6-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index d1216760d025564eecdb1deea5576335bf93ed81..1306112d76486f5060756f62654285a347042f46 100644 (file)
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -602,25 +602,6 @@ u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v)
 }
 EXPORT_SYMBOL_GPL(__blkg_prfill_u64);
 
-/* Performs queue bypass and policy enabled checks then looks up blkg. */
-static struct blkcg_gq *blkg_lookup_check(struct blkcg *blkcg,
-                                         const struct blkcg_policy *pol,
-                                         struct request_queue *q)
-{
-       struct blkcg_gq *blkg;
-
-       WARN_ON_ONCE(!rcu_read_lock_held());
-       lockdep_assert_held(&q->queue_lock);
-
-       if (!blkcg_policy_enabled(q, pol))
-               return ERR_PTR(-EOPNOTSUPP);
-
-       blkg = blkg_lookup(blkcg, q);
-       if (blkg)
-               blkg_update_hint(blkcg, blkg);
-       return blkg;
-}
-
 /**
  * blkcg_conf_open_bdev - parse and open bdev for per-blkg config update
  * @inputp: input string pointer
@@ -697,14 +678,16 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
        rcu_read_lock();
        spin_lock_irq(&q->queue_lock);
 
-       blkg = blkg_lookup_check(blkcg, pol, q);
-       if (IS_ERR(blkg)) {
-               ret = PTR_ERR(blkg);
+       if (!blkcg_policy_enabled(q, pol)) {
+               ret = -EOPNOTSUPP;
                goto fail_unlock;
        }
 
-       if (blkg)
+       blkg = blkg_lookup(blkcg, q);
+       if (blkg) {
+               blkg_update_hint(blkcg, blkg);
                goto success;
+       }
 
        /*
         * Create blkgs walking down from blkcg_root to @blkcg, so that all
@@ -740,14 +723,15 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
                rcu_read_lock();
                spin_lock_irq(&q->queue_lock);
 
-               blkg = blkg_lookup_check(pos, pol, q);
-               if (IS_ERR(blkg)) {
-                       ret = PTR_ERR(blkg);
+               if (!blkcg_policy_enabled(q, pol)) {
                        blkg_free(new_blkg);
+                       ret = -EOPNOTSUPP;
                        goto fail_preloaded;
                }
 
+               blkg = blkg_lookup(pos, q);
                if (blkg) {
+                       blkg_update_hint(pos, blkg);
                        blkg_free(new_blkg);
                } else {
                        blkg = blkg_create(pos, q, new_blkg);