Re: [Kiobuf-io-devel] RFC: Kernel mechanism: Compound event wait

Jens Axboe
2001-02-07T01:40:38Z

On Tue, Feb 06 2001, Linus Torvalds wrote:
> > I don't see anything that would break doing this, in fact you can
> > do this as long as the buffers are all at least a multiple of the
> > block size. All the drivers I've inspected handle this fine, noone
> > assumes that rq->bh->b_size is the same in all the buffers attached
> > to the request.
>
> It's really easy to get this wrong when going forward in the request list:
> you need to make sure that you update "request->current_nr_sectors" each
> time you move on to the next bh.
>
> I would not be surprised if some of them have been seriously buggered.

Maybe have been, but it looks good at least with the general drivers
that I mentioned.

> [...] so I would be _really_ nervous about just turning it on
> silently. This is all very much a 2.5.x-kind of thing ;)

Then you might want to apply this :-)

--- drivers/block/ll_rw_blk.c~ Wed Feb 7 02:38:31 2001
+++ drivers/block/ll_rw_blk.c Wed Feb 7 02:38:42 2001
@@ -1048,7 +1048,7 @@
/* Verify requested block sizes. */
for (i = 0; i < nr; i++) {
struct buffer_head *bh = bhs[i];
- if (bh->b_size % correct_size) {
+ if (bh->b_size != correct_size) {
printk(KERN_NOTICE "ll_rw_block: device %s: "
"only %d-char blocks implemented (%u)\n",
kdevname(bhs[0]->b_dev),

--
Jens Axboe