ext4: flush background discard kwork when retry allocation
The background discard kwork tries to mark blocks used and issue
discard. This can make filesystem suffer from NOSPC error, xfstest
generic/371 can fail due to it. Fix it by flushing discard kwork
in ext4_should_retry_alloc. At the same time, give up discard at
the moment.
Signed-off-by: Wang Jianchao <wangjianchao@kuaishou.com>
Link: https://lore.kernel.org/r/20210830075246.12516-6-jianchao.wan9@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 907b357..34670cb 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -3331,9 +3331,11 @@ static void ext4_discard_work(struct work_struct *work)
load_grp = UINT_MAX;
list_for_each_entry_safe(fd, nfd, &discard_list, efd_list) {
/*
- * If filesystem is umounting or no memory, give up the discard
+ * If filesystem is umounting or no memory or suffering
+ * from no space, give up the discard
*/
- if ((sb->s_flags & SB_ACTIVE) && !err) {
+ if ((sb->s_flags & SB_ACTIVE) && !err &&
+ !atomic_read(&sbi->s_retry_alloc_pending)) {
grp = fd->efd_group;
if (grp != load_grp) {
if (load_grp != UINT_MAX)
@@ -3431,6 +3433,7 @@ int ext4_mb_init(struct super_block *sb)
INIT_LIST_HEAD(&sbi->s_freed_data_list);
INIT_LIST_HEAD(&sbi->s_discard_list);
INIT_WORK(&sbi->s_discard_work, ext4_discard_work);
+ atomic_set(&sbi->s_retry_alloc_pending, 0);
sbi->s_mb_max_to_scan = MB_DEFAULT_MAX_TO_SCAN;
sbi->s_mb_min_to_scan = MB_DEFAULT_MIN_TO_SCAN;