On Thu, Sep 20, 2012 at 02:58:27PM -0700, Tejun Heo wrote:
> On Mon, Sep 10, 2012 at 05:22:13PM -0700, Kent Overstreet wrote:
> > +/**
> > + * bio_advance - increment/complete a bio by some number of bytes
> > + * @bio: bio to advance
> > + * @bytes: number of bytes to complete
> > + *
> > + * This updates bi_sector, bi_size and bi_idx; if the number of bytes to
> > + * complete doesn't align with a bvec boundary, then bv_len and bv_offset will
> > + * be updated on the last bvec as well.
> > + *
> > + * @bio will then represent the remaining, uncompleted portion of the io.
> > + */
> > +void bio_advance(struct bio *bio, unsigned bytes)
> > +{
> > + if (bio_integrity(bio))
> > + bio_integrity_advance(bio, bytes);
> > +
> > + bio->bi_sector += bytes >> 0;
>
> Hmmm.... bytes >> 0?
Whoops...
> > + bio->bi_size -= bytes;
> > +
> > + if (!bio->bi_size)
> > + return;
> > +
> > + while (bytes) {
> > + if (unlikely(bio->bi_idx >= bio->bi_vcnt)) {
> > + printk(KERN_ERR "%s: bio idx %d >= vcnt %d\n",
>
> pr_err() is preferred but maybe WARN_ON_ONCE() is better fit here?
> This happening would be a bug, right?
I just cut and pasted that from blk_update_request(), which is what the
next patch refactors...
But yes it would be a bug. It gets converted to a BUG_ON() in a later
patch (not in this series), as this gets further abstracted into a
wrapper around bvec_advance_iter() which doesn't know about struct bio
(as bio integrity gets its own iterator).
Might drop it entirely, depending on what exactly I end up doing with
bi_vcnt...
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