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>

diff --git a/fs/dcache.c b/fs/dcache.c
index 1f24cd684c512e65e6b0e381e5af0ab8e810919d..eacc853a2e3a64a3081a5cc0866d1e35a90979a7 100644 (file)
--- 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;