[PATCH] use get_fs_struct() in proc

This patch cleans up proc_cwd_link() and proc_root_link() by factoring
out common code into get_fs_struct().

Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Cc: <viro@parcelfarce.linux.theplanet.co.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>