From: Al Viro <viro@zeniv.linux.org.uk>
Date: Sat, 16 Jan 2010 17:56:08 +0000 (-0500)
Subject: may_umount() needs namespace_sem
X-Git-Tag: v3.12-rc1~11526^2~4
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=8ad08d8a0c3823e9b06ef84c362c9361be323d2d;p=kernel%2Fkernel-generic.git

may_umount() needs namespace_sem

otherwise it races with clone_mnt() changing mnt_share/mnt_slaves

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---

diff --git a/fs/namespace.c b/fs/namespace.c
index 7d70d63..461090a 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -965,10 +965,12 @@ EXPORT_SYMBOL(may_umount_tree);
 int may_umount(struct vfsmount *mnt)
 {
 	int ret = 1;
+	down_read(&namespace_sem);
 	spin_lock(&vfsmount_lock);
 	if (propagate_mount_busy(mnt, 2))
 		ret = 0;
 	spin_unlock(&vfsmount_lock);
+	up_read(&namespace_sem);
 	return ret;
 }