linux-kernel - [PATCH 13/29] ext4: dynamically allocate the ext4-es shrinker

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Message-Id: <20230622085335.77010-14-zhengqi.arch@bytedance.com>
Date:   Thu, 22 Jun 2023 16:53:19 +0800
From:   Qi Zheng <zhengqi.arch@...edance.com>
To:     akpm@...ux-foundation.org, david@...morbit.com, tkhai@...ru,
        vbabka@...e.cz, roman.gushchin@...ux.dev, djwong@...nel.org,
        brauner@...nel.org, paulmck@...nel.org, tytso@....edu
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-arm-msm@...r.kernel.org, dm-devel@...hat.com,
        linux-raid@...r.kernel.org, linux-bcache@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org,
        linux-nfs@...r.kernel.org, linux-xfs@...r.kernel.org,
        linux-btrfs@...r.kernel.org, Qi Zheng <zhengqi.arch@...edance.com>
Subject: [PATCH 13/29] ext4: dynamically allocate the ext4-es shrinker

In preparation for implementing lockless slab shrink,
we need to dynamically allocate the ext4-es shrinker,
so that it can be freed asynchronously using kfree_rcu().
Then it doesn't need to wait for RCU read-side critical
section when releasing the struct ext4_sb_info.

Signed-off-by: Qi Zheng <zhengqi.arch@...edance.com>
---
 fs/ext4/ext4.h           |  2 +-
 fs/ext4/extents_status.c | 21 ++++++++++++---------
 2 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 0a2d55faa095..1bd150d454f5 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1651,7 +1651,7 @@ struct ext4_sb_info {
 	__u32 s_csum_seed;
 
 	/* Reclaim extents from extent status tree */
-	struct shrinker s_es_shrinker;
+	struct shrinker *s_es_shrinker;
 	struct list_head s_es_list;	/* List of inodes with reclaimable extents */
 	long s_es_nr_inode;
 	struct ext4_es_stats s_es_stats;
diff --git a/fs/ext4/extents_status.c b/fs/ext4/extents_status.c
index 9b5b8951afb4..fea82339f4b4 100644
--- a/fs/ext4/extents_status.c
+++ b/fs/ext4/extents_status.c
@@ -1596,7 +1596,7 @@ static unsigned long ext4_es_count(struct shrinker *shrink,
 	unsigned long nr;
 	struct ext4_sb_info *sbi;
 
-	sbi = container_of(shrink, struct ext4_sb_info, s_es_shrinker);
+	sbi = shrink->private_data;
 	nr = percpu_counter_read_positive(&sbi->s_es_stats.es_stats_shk_cnt);
 	trace_ext4_es_shrink_count(sbi->s_sb, sc->nr_to_scan, nr);
 	return nr;
@@ -1605,8 +1605,7 @@ static unsigned long ext4_es_count(struct shrinker *shrink,
 static unsigned long ext4_es_scan(struct shrinker *shrink,
 				  struct shrink_control *sc)
 {
-	struct ext4_sb_info *sbi = container_of(shrink,
-					struct ext4_sb_info, s_es_shrinker);
+	struct ext4_sb_info *sbi = shrink->private_data;
 	int nr_to_scan = sc->nr_to_scan;
 	int ret, nr_shrunk;
 
@@ -1690,15 +1689,19 @@ int ext4_es_register_shrinker(struct ext4_sb_info *sbi)
 	if (err)
 		goto err3;
 
-	sbi->s_es_shrinker.scan_objects = ext4_es_scan;
-	sbi->s_es_shrinker.count_objects = ext4_es_count;
-	sbi->s_es_shrinker.seeks = DEFAULT_SEEKS;
-	err = register_shrinker(&sbi->s_es_shrinker, "ext4-es:%s",
+	sbi->s_es_shrinker = shrinker_alloc_and_init(ext4_es_count, ext4_es_scan,
+						     0, DEFAULT_SEEKS, 0, sbi);
+	if (!sbi->s_es_shrinker)
+		goto err4;
+
+	err = register_shrinker(sbi->s_es_shrinker, "ext4-es:%s",
 				sbi->s_sb->s_id);
 	if (err)
-		goto err4;
+		goto err5;
 
 	return 0;
+err5:
+	shrinker_free(sbi->s_es_shrinker);
 err4:
 	percpu_counter_destroy(&sbi->s_es_stats.es_stats_shk_cnt);
 err3:
@@ -1716,7 +1719,7 @@ void ext4_es_unregister_shrinker(struct ext4_sb_info *sbi)
 	percpu_counter_destroy(&sbi->s_es_stats.es_stats_cache_misses);
 	percpu_counter_destroy(&sbi->s_es_stats.es_stats_all_cnt);
 	percpu_counter_destroy(&sbi->s_es_stats.es_stats_shk_cnt);
-	unregister_shrinker(&sbi->s_es_shrinker);
+	unregister_and_free_shrinker(sbi->s_es_shrinker);
 }
 
 /*
-- 
2.30.2