Messages in this thread | | | Subject | Re: [PATCH] block: fix residual byte count handling | From | FUJITA Tomonori <> | Date | Mon, 03 Mar 2008 17:26:23 +0900 |
| |
On Mon, 03 Mar 2008 13:09:13 +0900 Tejun Heo <htejun@gmail.com> wrote:
> FUJITA Tomonori wrote: > >> - I think bugs caused by using raw_data_len instead of data_len are more > >> subtle than the other way around. Using data_len instead of > >> raw_data_len usually affects the application layer while using > >> raw_data_len instead of data_len affects the DMA engine and transport layer. > > > > If we add extra_len, we can get what raw_data_len and data_len > > provide. > > > > I can't see what changing the meaning of rq->data_len (and > > investigating all the block drivers) gives us. > > No matter which way you go, you change the meaning of rq->data_len and > you MUST inspect rq->data_len usage whichever way you go.
The patch doens't change that rq->data_len means the true data length. But yeah, it breaks rq->data_len == sum(sg). So it might break some drivers.
> Apply your patch and try to do sg IO on IDE cdrom w/ various > transfer lengths.
I've just tried the patch with both ata and libata and it seems to work.
For anyone hitting this problem, please try the following patch:
http://lkml.org/lkml/2008/3/2/218
Thanks,
| |