Revert "vfs: show unreachable paths in getcwd and proc"

Because it caused a chroot ttyname regression in 2.6.36.

As of 2.6.36 ttyname does not work in a chroot. It has already been
reported that screen breaks, and for me this breaks an automated
distribution testsuite, that I need to preserve the ability to run the
existing binaries on for several more years. glibc 2.11.3 which has a
fix for this is not an option.

The root cause of this breakage is:

commit 8df9d1a4142311c084ffeeacb67cd34d190eff74
Author: Miklos Szeredi <[e-mail]>
Date: Tue Aug 10 11:41:41 2010 +0200

vfs: show unreachable paths in getcwd and proc

Prepend "(unreachable)" to path strings if the path is not reachable
from the current root.

Two places updated are
- the return string from getcwd()
- and symlinks under /proc/$PID.

Other uses of d_path() are left unchanged (we know that some old
software crashes if /proc/mounts is changed).

Signed-off-by: Miklos Szeredi <[e-mail]>
Signed-off-by: Al Viro <[e-mail]>

So remove the nice sounding, but ultimately ill advised change to how
/proc/fd symlinks work.

Signed-off-by: "Eric W. Biederman" <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

fs/proc/base.c

···
 	if (!tmp)
 		return -ENOMEM;
 
-	pathname = d_path_with_unreachable(path, tmp, PAGE_SIZE);
+	pathname = d_path(path, tmp, PAGE_SIZE);
 	len = PTR_ERR(pathname);
 	if (IS_ERR(pathname))
 		goto out;