quota: fix potential infinite loop

In dquot_writeback_dquots(), we write back dquot from dirty dquots
list. There is a potential infinite loop if ->write_dquot() failure
and forget remove dquot from the list. This patch clear dirty bit
anyway to avoid it.

Signed-off-by: zhangyi (F) <yi.zhang@huawei.com>
Signed-off-by: Jan Kara <jack@suse.cz>

1 files changed, 9 insertions, 2 deletions

diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 50b0556a124f..f68397923ebb 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -644,8 +644,15 @@ int dquot_writeback_dquots(struct super_block *sb, int type)
                         spin_unlock(&dq_list_lock);
                         dqstats_inc(DQST_LOOKUPS);
                         err = sb->dq_op->write_dquot(dquot);
-                        if (!ret && err)
-                                ret = err;
+                        if (err) {
+                                /*
+                                 * Clear dirty bit anyway to avoid infinite
+                                 * loop here.
+                                 */
+                                clear_dquot_dirty(dquot);
+                                if (!ret)
+                                        ret = err;
+                        }
                         dqput(dquot);
                         spin_lock(&dq_list_lock);
                 }