fix unpaired rcu lock in prepend_path()

Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/dcache.c b/fs/dcache.c
index 1f24cd684c51..eacc853a2e3a 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2924,6 +2924,7 @@ static int prepend_path(const struct path *path,
 restart_mnt:
         read_seqbegin_or_lock(&mount_lock, &m_seq);
         seq = 0;
+        rcu_read_lock();
 restart:
         bptr = *buffer;
         blen = *buflen;
@@ -2971,6 +2972,9 @@ restart:
                 goto restart;
         }
         done_seqretry(&rename_lock, seq);
+
+        if (!(m_seq & 1))
+                rcu_read_unlock();
         if (need_seqretry(&mount_lock, m_seq)) {
                 m_seq = 1;
                 goto restart_mnt;