iget: stop EXT2 from using iget() and read_inode()

iget: stop EXT2 from using iget() and read_inode()

Stop the EXT2 filesystem from using iget() and read_inode().  Replace
ext2_read_inode() with ext2_iget(), and call that instead of iget().
ext2_iget() then uses iget_locked() directly and returns a proper error code
instead of an inode in the event of an error.

ext2_fill_super() returns any error incurred when getting the root inode
instead of EINVAL.

[[email protected]: coding-style fixes]
Signed-off-by: David Howells <[email protected]>
Acked-by: "Theodore Ts'o" <[email protected]>
Cc: <[email protected]>
Acked-by: Christoph Hellwig <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>