iget: stop EXT3 from using iget() and read_inode()

iget: stop EXT3 from using iget() and read_inode()

Stop the EXT3 filesystem from using iget() and read_inode().  Replace
ext3_read_inode() with ext3_iget(), and call that instead of iget().
ext3_iget() then uses iget_locked() directly and returns a proper error code
instead of an inode in the event of an error.

ext3_fill_super() returns any error incurred when getting the root inode
instead of EINVAL.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: "Theodore Ts'o" <tytso@mit.edu>
Acked-by: Jan Kara <jack@suse.cz>
Cc: <linux-ext4@vger.kernel.org>
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>