From e249cdb4e64166c33a62cd34f8e33e86a05ecbe9 Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@suse.cz>
Date: Wed, 27 Jul 2022 09:33:48 +0000
Subject: [PATCH] mbcache: Don't reclaim used entries
hulk inclusion
category: bugfix
bugzilla: 186975, https://gitee.com/openeuler/kernel/issues/I5HT6F
CVE: NA
Reference: https://patchwork.ozlabs.org/project/linux-ext4/list/?series=309169
--------------------------------
Do not reclaim entries that are currently used by somebody from a
shrinker. Firstly, these entries are likely useful. Secondly, we will
need to keep such entries to protect pending increment of xattr block
refcount.
CC: stable@vger.kernel.org
Fixes: 82939d7999df ("ext4: convert to mbcache2")
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>
---
fs/mbcache.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/fs/mbcache.c b/fs/mbcache.c
index 081ccf0caee3..12203e5a91e7 100644
--- a/fs/mbcache.c
+++ b/fs/mbcache.c
@@ -287,7 +287,7 @@ static unsigned long mb_cache_shrink(struct mb_cache *cache,
while (nr_to_scan-- && !list_empty(&cache->c_list)) {
entry = list_first_entry(&cache->c_list,
struct mb_cache_entry, e_list);
- if (entry->e_referenced) {
+ if (entry->e_referenced || atomic_read(&entry->e_refcnt) > 2) {
entry->e_referenced = 0;
list_move_tail(&entry->e_list, &cache->c_list);
continue;
@@ -301,6 +301,14 @@ static unsigned long mb_cache_shrink(struct mb_cache *cache,
spin_unlock(&cache->c_list_lock);
head = mb_cache_entry_head(cache, entry->e_key);
hlist_bl_lock(head);
+ /* Now a reliable check if the entry didn't get used... */
+ if (atomic_read(&entry->e_refcnt) > 2) {
+ hlist_bl_unlock(head);
+ spin_lock(&cache->c_list_lock);
+ list_add_tail(&entry->e_list, &cache->c_list);
+ cache->c_entry_count++;
+ continue;
+ }
if (!hlist_bl_unhashed(&entry->e_hash_list)) {
hlist_bl_del_init(&entry->e_hash_list);
atomic_dec(&entry->e_refcnt);
--
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