From: Jan Kara <jack@suse.cz>
Date: Thu, 8 Jun 2017 13:05:08 +0000 (+0200)
Subject: quota: Acquire dqio_sem for reading in dquot_get_next_id()
X-Git-Tag: v4.14-rc1~103^2~25
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0cff9151d3fa27574c2201377a080e1b9b87b8ba;p=thirdparty%2Flinux.git

quota: Acquire dqio_sem for reading in dquot_get_next_id()

dquot_get_next_id() needs dqio_sem only for reading to protect against
racing with modification of quota file structure.

Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Jan Kara <jack@suse.cz>
---

diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 21358f31923d8..8d5ccad3bf3ea 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -2079,9 +2079,9 @@ int dquot_get_next_id(struct super_block *sb, struct kqid *qid)
 		return -ESRCH;
 	if (!dqopt->ops[qid->type]->get_next_id)
 		return -ENOSYS;
-	down_write(&dqopt->dqio_sem);
+	down_read(&dqopt->dqio_sem);
 	err = dqopt->ops[qid->type]->get_next_id(sb, qid);
-	up_write(&dqopt->dqio_sem);
+	up_read(&dqopt->dqio_sem);
 	return err;
 }
 EXPORT_SYMBOL(dquot_get_next_id);