| From 58318914186c157477b978b1739dfe2f1b9dc0fe Mon Sep 17 00:00:00 2001 |
| From: Jan Kara <jack@suse.cz> |
| Date: Tue, 12 Jul 2022 12:54:20 +0200 |
| Subject: mbcache: don't reclaim used entries |
| |
| From: Jan Kara <jack@suse.cz> |
| |
| commit 58318914186c157477b978b1739dfe2f1b9dc0fe upstream. |
| |
| 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> |
| Link: https://lore.kernel.org/r/20220712105436.32204-1-jack@suse.cz |
| Signed-off-by: Theodore Ts'o <tytso@mit.edu> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| fs/mbcache.c | 10 +++++++++- |
| 1 file changed, 9 insertions(+), 1 deletion(-) |
| |
| --- a/fs/mbcache.c |
| +++ b/fs/mbcache.c |
| @@ -288,7 +288,7 @@ static unsigned long mb_cache_shrink(str |
| 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(str |
| 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); |
