v9fs_vfs_readlink allocates space for the link using __getname and
errorneously uses strlen on the newly allocated buffer to check if the buffer
passed by the user is bigger than the one returned by __getname.

The patch replaces the strlen usage to PATH_MAX, which is the actual size of
the buffers returned by __getname.
Signed-off-by: Latchesar Ionkov <lucho@ionkov.net>
Cc: Eric Van Hensbergen <ericvh@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>