Commit 2bbd9505 authored by Jan Kara's avatar Jan Kara Committed by Zheng Zengkai
Browse files

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: 82939d79 ("ext4: convert to mbcache2")
Signed-off-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarZhihao Cheng <chengzhihao1@huawei.com>
Reviewed-by: default avatarZhang Yi <yi.zhang@huawei.com>
Signed-off-by: default avatarZheng Zengkai <zhengzengkai@huawei.com>
parent c13c2cd2

fs/mbcache.c

+9 −1
Original line number Diff line number Diff line
@@ -288,7 +288,7 @@ 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;
@@ -302,6 +302,14 @@ 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);