linux-kernel - [PATCH v2] f2fs: shrink spinlock coverage

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20200506104542.123575-1-yuchao0@huawei.com>
Date:   Wed, 6 May 2020 18:45:42 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     <jaegeuk@...nel.org>
CC:     <linux-f2fs-devel@...ts.sourceforge.net>,
        <linux-kernel@...r.kernel.org>, <chao@...nel.org>,
        Chao Yu <yuchao0@...wei.com>
Subject: [PATCH v2] f2fs: shrink spinlock coverage

In f2fs_try_to_free_nids(), .nid_list_lock spinlock critical region will
increase as expected shrink number increase, to avoid spining other CPUs
for long time, it's better to implement like extent cache and nats
shrinker.

Signed-off-by: Chao Yu <yuchao0@...wei.com>
---
v2:
- fix unlock wrong spinlock.
 fs/f2fs/node.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index 4da0d8713df5..ad0b14f4dab8 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -2488,7 +2488,6 @@ void f2fs_alloc_nid_failed(struct f2fs_sb_info *sbi, nid_t nid)
 int f2fs_try_to_free_nids(struct f2fs_sb_info *sbi, int nr_shrink)
 {
 	struct f2fs_nm_info *nm_i = NM_I(sbi);
-	struct free_nid *i, *next;
 	int nr = nr_shrink;
 
 	if (nm_i->nid_cnt[FREE_NID] <= MAX_FREE_NIDS)
@@ -2498,14 +2497,22 @@ int f2fs_try_to_free_nids(struct f2fs_sb_info *sbi, int nr_shrink)
 		return 0;
 
 	spin_lock(&nm_i->nid_list_lock);
-	list_for_each_entry_safe(i, next, &nm_i->free_nid_list, list) {
-		if (nr_shrink <= 0 ||
-				nm_i->nid_cnt[FREE_NID] <= MAX_FREE_NIDS)
+	while (nr_shrink) {
+		struct free_nid *i;
+
+		if (nm_i->nid_cnt[FREE_NID] <= MAX_FREE_NIDS)
 			break;
 
+		i = list_first_entry(&nm_i->free_nid_list,
+					struct free_nid, list);
+		list_del(&i->list);
+		spin_unlock(&nm_i->nid_list_lock);
+
 		__remove_free_nid(sbi, i, FREE_NID);
 		kmem_cache_free(free_nid_slab, i);
 		nr_shrink--;
+
+		spin_lock(&nm_i->nid_list_lock);
 	}
 	spin_unlock(&nm_i->nid_list_lock);
 	mutex_unlock(&nm_i->build_lock);
-- 
2.18.0.rc1