Re: [PATCH v2] iomap: return partial I/O count on error in iomap_dio_bio_actor

Goldwyn Rodrigues
2020-02-28T20:35:43Z

On 11:59 28/02, Matthew Wilcox wrote:
> On Fri, Feb 28, 2020 at 01:44:01PM -0600, Goldwyn Rodrigues wrote:
> > +++ b/fs/iomap/direct-io.c
> > @@ -264,7 +264,7 @@ iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length,
> > size_t n;
> > if (dio->error) {
> > iov_iter_revert(dio->submit.iter, copied);
> > - copied = ret = 0;
> > + ret = 0;
> > goto out;
>
> There's another change here ... look at the out label
>
> out:
> /* Undo iter limitation to current extent */
> iov_iter_reexpand(dio->submit.iter, orig_count - copied);
> if (copied)
> return copied;
> return ret;
>
> so you're also changing by how much the iter is reexpanded. I
> don't know if it's the appropriate amount; I still don't quite get the
> iov_iter complexities.
>

Ah, okay. Now I understand what Christoph was saying.

I suppose it is safe to remove iov_iter_reexpand(). I don't see any
other goto to this label which will have a non-zero copied value.
And we have already performed the iov_iter_revert().

--
Goldwyn