ext4: fix async i/o writes beyond 4GB to a sparse file

ext4: fix async i/o writes beyond 4GB to a sparse file

commit a1de02dccf906faba2ee2d99cac56799bda3b96a upstream.

The "offset" member in ext4_io_end holds bytes, not blocks, so
ext4_lblk_t is wrong - and too small (u32).

This caused the async i/o writes to sparse files beyond 4GB to fail
when they wrapped around to 0.

Also fix up the type of arguments to ext4_convert_unwritten_extents(),
it gets ssize_t from ext4_end_aio_dio_nolock() and
ext4_ext_direct_IO().

Reported-by: Giel de Nijs <giel@vectorwise.com>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Cc: maximilian attems <max@stro.at>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>