quota: Handle Q_GETNEXTQUOTA when quota is disabled

Currently we oopsed when Q_GETNEXTQUOTA got called when quota was
disabled. Properly check whether quota is enabled for the filesystem
before calling into quota format handler.

Reported-by: Ted Tso <tytso@mit.edu>
Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index ba827daea5a0b2a7883327a18a83a43315c9bd2a..ff21980d0119a58aa41c825258e435aa799042c7 100644 (file)
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -2047,11 +2047,20 @@ int dquot_get_next_id(struct super_block *sb, struct kqid *qid)
        struct quota_info *dqopt = sb_dqopt(sb);
        int err;
 
-       if (!dqopt->ops[qid->type]->get_next_id)
-               return -ENOSYS;
+       mutex_lock(&dqopt->dqonoff_mutex);
+       if (!sb_has_quota_active(sb, qid->type)) {
+               err = -ESRCH;
+               goto out;
+       }
+       if (!dqopt->ops[qid->type]->get_next_id) {
+               err = -ENOSYS;
+               goto out;
+       }
        mutex_lock(&dqopt->dqio_mutex);
        err = dqopt->ops[qid->type]->get_next_id(sb, qid);
        mutex_unlock(&dqopt->dqio_mutex);
+out:
+       mutex_unlock(&dqopt->dqonoff_mutex);
 
        return err;
 }