linux-kernel - [PATCH v6 34/45] xfs: dynamically allocate the xfs-buf shrinker

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Message-Id: <20230911094444.68966-35-zhengqi.arch@bytedance.com>
Date:   Mon, 11 Sep 2023 17:44:33 +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,
        steven.price@....com, cel@...nel.org, senozhatsky@...omium.org,
        yujie.liu@...el.com, gregkh@...uxfoundation.org,
        muchun.song@...ux.dev
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-fsdevel@...r.kernel.org,
        Qi Zheng <zhengqi.arch@...edance.com>,
        Muchun Song <songmuchun@...edance.com>,
        Chandan Babu R <chandan.babu@...cle.com>,
        linux-xfs@...r.kernel.org
Subject: [PATCH v6 34/45] xfs: dynamically allocate the xfs-buf shrinker

In preparation for implementing lockless slab shrink, use new APIs to
dynamically allocate the xfs-buf shrinker, so that it can be freed
asynchronously via RCU. Then it doesn't need to wait for RCU read-side
critical section when releasing the struct xfs_buftarg.

Signed-off-by: Qi Zheng <zhengqi.arch@...edance.com>
Reviewed-by: Muchun Song <songmuchun@...edance.com>
CC: Chandan Babu R <chandan.babu@...cle.com>
CC: "Darrick J. Wong" <djwong@...nel.org>
CC: linux-xfs@...r.kernel.org
---
 fs/xfs/xfs_buf.c | 24 +++++++++++++-----------
 fs/xfs/xfs_buf.h |  2 +-
 2 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index c1ece4a08ff4..9e7ba04572db 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -1913,8 +1913,7 @@ xfs_buftarg_shrink_scan(
 	struct shrinker		*shrink,
 	struct shrink_control	*sc)
 {
-	struct xfs_buftarg	*btp = container_of(shrink,
-					struct xfs_buftarg, bt_shrinker);
+	struct xfs_buftarg	*btp = shrink->private_data;
 	LIST_HEAD(dispose);
 	unsigned long		freed;
 
@@ -1936,8 +1935,7 @@ xfs_buftarg_shrink_count(
 	struct shrinker		*shrink,
 	struct shrink_control	*sc)
 {
-	struct xfs_buftarg	*btp = container_of(shrink,
-					struct xfs_buftarg, bt_shrinker);
+	struct xfs_buftarg	*btp = shrink->private_data;
 	return list_lru_shrink_count(&btp->bt_lru, sc);
 }
 
@@ -1947,7 +1945,7 @@ xfs_free_buftarg(
 {
 	struct block_device	*bdev = btp->bt_bdev;
 
-	unregister_shrinker(&btp->bt_shrinker);
+	shrinker_free(btp->bt_shrinker);
 	ASSERT(percpu_counter_sum(&btp->bt_io_count) == 0);
 	percpu_counter_destroy(&btp->bt_io_count);
 	list_lru_destroy(&btp->bt_lru);
@@ -2031,13 +2029,17 @@ xfs_alloc_buftarg(
 	if (percpu_counter_init(&btp->bt_io_count, 0, GFP_KERNEL))
 		goto error_lru;
 
-	btp->bt_shrinker.count_objects = xfs_buftarg_shrink_count;
-	btp->bt_shrinker.scan_objects = xfs_buftarg_shrink_scan;
-	btp->bt_shrinker.seeks = DEFAULT_SEEKS;
-	btp->bt_shrinker.flags = SHRINKER_NUMA_AWARE;
-	if (register_shrinker(&btp->bt_shrinker, "xfs-buf:%s",
-			      mp->m_super->s_id))
+	btp->bt_shrinker = shrinker_alloc(SHRINKER_NUMA_AWARE, "xfs-buf:%s",
+					  mp->m_super->s_id);
+	if (!btp->bt_shrinker)
 		goto error_pcpu;
+
+	btp->bt_shrinker->count_objects = xfs_buftarg_shrink_count;
+	btp->bt_shrinker->scan_objects = xfs_buftarg_shrink_scan;
+	btp->bt_shrinker->private_data = btp;
+
+	shrinker_register(btp->bt_shrinker);
+
 	return btp;
 
 error_pcpu:
diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index df8f47953bb4..702e7d9ea2ac 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -108,7 +108,7 @@ typedef struct xfs_buftarg {
 	size_t			bt_logical_sectormask;
 
 	/* LRU control structures */
-	struct shrinker		bt_shrinker;
+	struct shrinker		*bt_shrinker;
 	struct list_lru		bt_lru;
 
 	struct percpu_counter	bt_io_count;
-- 
2.30.2