[PATCH] namei fixes (5/19)

fix for too early mntput() in open_namei() - we pin path.mnt down for the
duration of __do_follow_link().  Otherwise we could get the fs where our
symlink lived unmounted while we were in __do_follow_link().  That would end
up with dentry of symlink staying pinned down through the fs shutdown.
Signed-off-by: NAl Viro <viro@parcelfarce.linux.theplanet.co.uk>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

fs/namei.c

@@ -1524,8 +1524,10 @@ int open_namei(const char * pathname, int flag, int mode, struct nameidata *nd)
 	error = security_inode_follow_link(path.dentry, nd);
 	if (error)
 		goto exit_dput;
+	mntget(path.mnt);
 	error = __do_follow_link(path.dentry, nd);
 	dput(path.dentry);
+	mntput(path.mnt);
 	path.mnt = nd->mnt;
 	if (error)
 		return error;