iget: stop autofs from using iget() and read_inode()

iget: stop autofs from using iget() and read_inode()

Stop the autofs filesystem from using iget() and read_inode().  Replace
autofs_read_inode() with autofs_iget(), and call that instead of iget().
autofs_iget() then uses iget_locked() directly and returns a proper error code
instead of an inode in the event of an error.

Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Ian Kent <raven@themaw.net>
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>