From: Christoph Hellwig hch@lst.de
[ Upstream commit 4a69f325aa43847e0827fbfe4b3623307b0c9baa ]
Add a fully inlined blkg_lookup as the extra two checks aren't going to generated a lot more code vs the call to the slowpath routine, and open code the hint update in the two callers that care.
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/20220921180501.1539876-5-hch@lst.de Signed-off-by: Jens Axboe axboe@kernel.dk Stable-dep-of: 813e693023ba ("blk-iolatency: Fix memory leak on add_disk() failures") Signed-off-by: Sasha Levin sashal@kernel.org --- block/blk-cgroup.c | 38 +++++++++++++++----------------------- block/blk-cgroup.h | 39 ++++++++++++--------------------------- 2 files changed, 27 insertions(+), 50 deletions(-)
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index ee48b6f4d5d4..f66cf1734e84 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -263,29 +263,13 @@ static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q, return NULL; }
-struct blkcg_gq *blkg_lookup_slowpath(struct blkcg *blkcg, - struct request_queue *q, bool update_hint) +static void blkg_update_hint(struct blkcg *blkcg, struct blkcg_gq *blkg) { - struct blkcg_gq *blkg; - - /* - * Hint didn't match. Look up from the radix tree. Note that the - * hint can only be updated under queue_lock as otherwise @blkg - * could have already been removed from blkg_tree. The caller is - * responsible for grabbing queue_lock if @update_hint. - */ - blkg = radix_tree_lookup(&blkcg->blkg_tree, q->id); - if (blkg && blkg->q == q) { - if (update_hint) { - lockdep_assert_held(&q->queue_lock); - rcu_assign_pointer(blkcg->blkg_hint, blkg); - } - return blkg; - } + lockdep_assert_held(&blkg->q->queue_lock);
- return NULL; + if (blkcg != &blkcg_root && blkg != rcu_dereference(blkcg->blkg_hint)) + rcu_assign_pointer(blkcg->blkg_hint, blkg); } -EXPORT_SYMBOL_GPL(blkg_lookup_slowpath);
/* * If @new_blkg is %NULL, this function tries to allocate a new one as @@ -397,9 +381,11 @@ static struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, return blkg;
spin_lock_irqsave(&q->queue_lock, flags); - blkg = __blkg_lookup(blkcg, q, true); - if (blkg) + blkg = blkg_lookup(blkcg, q); + if (blkg) { + blkg_update_hint(blkcg, blkg); goto found; + }
/* * Create blkgs walking down from blkcg_root to @blkcg, so that all @@ -621,12 +607,18 @@ 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); - return __blkg_lookup(blkcg, q, true /* update_hint */); + + blkg = blkg_lookup(blkcg, q); + if (blkg) + blkg_update_hint(blkcg, blkg); + return blkg; }
/** diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h index 30396cad50e9..91b7ae0773be 100644 --- a/block/blk-cgroup.h +++ b/block/blk-cgroup.h @@ -178,8 +178,6 @@ struct blkcg_policy { extern struct blkcg blkcg_root; extern bool blkcg_debug_stats;
-struct blkcg_gq *blkg_lookup_slowpath(struct blkcg *blkcg, - struct request_queue *q, bool update_hint); int blkcg_init_queue(struct request_queue *q); void blkcg_exit_queue(struct request_queue *q);
@@ -227,22 +225,21 @@ static inline bool bio_issue_as_root_blkg(struct bio *bio) }
/** - * __blkg_lookup - internal version of blkg_lookup() + * blkg_lookup - lookup blkg for the specified blkcg - q pair * @blkcg: blkcg of interest * @q: request_queue of interest - * @update_hint: whether to update lookup hint with the result or not * - * This is internal version and shouldn't be used by policy - * implementations. Looks up blkgs for the @blkcg - @q pair regardless of - * @q's bypass state. If @update_hint is %true, the caller should be - * holding @q->queue_lock and lookup hint is updated on success. + * Lookup blkg for the @blkcg - @q pair. + + * Must be called in a RCU critical section. */ -static inline struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg, - struct request_queue *q, - bool update_hint) +static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, + struct request_queue *q) { struct blkcg_gq *blkg;
+ WARN_ON_ONCE(!rcu_read_lock_held()); + if (blkcg == &blkcg_root) return q->root_blkg;
@@ -250,22 +247,10 @@ static inline struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg, if (blkg && blkg->q == q) return blkg;
- return blkg_lookup_slowpath(blkcg, q, update_hint); -} - -/** - * blkg_lookup - lookup blkg for the specified blkcg - q pair - * @blkcg: blkcg of interest - * @q: request_queue of interest - * - * Lookup blkg for the @blkcg - @q pair. This function should be called - * under RCU read lock. - */ -static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, - struct request_queue *q) -{ - WARN_ON_ONCE(!rcu_read_lock_held()); - return __blkg_lookup(blkcg, q, false); + blkg = radix_tree_lookup(&blkcg->blkg_tree, q->id); + if (blkg && blkg->q != q) + blkg = NULL; + return blkg; }
/**