[PATCH v5 7/7] locks: Disable LOCK_MAND support for MS_SHARELOCK mounts

[Pavel Shilovsky]

Signed-off-by: Pavel Shilovsky <pias...@etersoft.ru>
---
 fs/locks.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/locks.c b/fs/locks.c
index 1402a43..a67857c 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -1719,6 +1719,12 @@ SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, 
cmd)
        if (!f.file)
                goto out;
 
+       /* Disable LOCK_MAND support for FS mounted with MS_SHARELOCK */
+       if (IS_SHARELOCK(f.file->f_path.dentry->d_inode)) {
+               error = -EPERM;
+               goto out;
+       }
+
        can_sleep = !(cmd & LOCK_NB);
        cmd &= ~LOCK_NB;
        unlock = (cmd == LOCK_UN);
-- 
1.8.1.5