On Mon, 03 Mar 2008 18:21:13 +0900 Tejun Heo <htejun@xxxxxxxxx> wrote: > FUJITA Tomonori wrote: > >>> 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. > > Yeah, that's what I was saying. You end up breaking one of the two > assumptions. As sglist is getting modified for any driver if it has DMA > alignment set, whether rq->data_len is adjusted together or not, sglist > and data_len usages have to be audited. My patch (well, James' original approach) doesn't affect drivers that don't use drain buffer. rq->data_len still means the true data length and rq->data_len is equal to sum(sg) for them. So right now we need to audit only libata. But your patch changes the meaning of rq->data_len. It affects all the drivers. So it breaks non libata stuff, like the SMP handler. We need to audit all the drivers. -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
