Re: [PATCH v4] iomap: add simple read path for small direct I/O

["Fengnan" <changfengnan@bytedance.com>]

在 2026/6/11 17:36, Pankaj Raghav (Samsung) 写道:
>> +static ssize_t iomap_dio_simple_read_complete(struct kiocb *iocb,
>> +		struct bio *bio)
>> +{
>> +	struct inode *inode = file_inode(iocb->ki_filp);
>> +	ssize_t ret;
>> +
>> +	WRITE_ONCE(iocb->private, NULL);
>> +
>> +	ret = iomap_dio_simple_read_finish(iocb, bio,
>> +			blk_status_to_errno(bio->bi_status));
>> +
>> +	inode_dio_end(inode);
>> +	trace_iomap_dio_complete(iocb, ret < 0 ? ret : 0, ret > 0 ? ret : 0);
> Shouldn't the second parameter here be
> blk_status_to_errno(bio->bi_status)?
>
> I think that will be more meaningful for tracing here.
> trace_iomap_dio_complete(iocb, blk_status_to_errno(bio->bi_status), ret);
Makes sense. I’ll update it in the next version.

>
> <snip>
>> +	return ret;
>> +}
>> +
>> +	sr->iocb = iocb;
>> +	sr->dio_flags = dio_flags;
>> +
>> +	bio->bi_iter.bi_sector = iomap_sector(&iomi.iomap, iomi.pos);
>> +	bio->bi_ioprio = iocb->ki_ioprio;
>> +	bio->bi_private = sr;
>> +	bio->bi_end_io = iomap_dio_simple_read_end_io;
>> +
>> +	if (dio_flags & IOMAP_DIO_BOUNCE)
>> +		ret = bio_iov_iter_bounce(bio, iter, count);
>> +	else
>> +		ret = bio_iov_iter_get_pages(bio, iter, alignment - 1);
>> +	if (unlikely(ret))
>> +		goto out_bio_put;
>> +
>> +	if (bio->bi_iter.bi_size != count) {
>> +		iov_iter_revert(iter, bio->bi_iter.bi_size);
>> +		ret = -ENOTBLK;
>> +		goto out_bio_release_pages;
>> +	}
>> +
>> +	sr->size = bio->bi_iter.bi_size;
>> +
>> +	if ((dio_flags & IOMAP_DIO_USER_BACKED) &&
>> +	    !(dio_flags & IOMAP_DIO_BOUNCE))
>> +		bio_set_pages_dirty(bio);
>> +
>> +	if (iocb->ki_flags & IOCB_NOWAIT)
>> +		bio->bi_opf |= REQ_NOWAIT;
>> +	if ((iocb->ki_flags & IOCB_HIPRI) && !wait_for_completion) {
>> +		bio->bi_opf |= REQ_POLLED;
>> +		bio_set_polled(bio, iocb);
> This results in build failure as the following patch removed this call:
> https://lore.kernel.org/linux-block/20260518062917.506483-1-hch@lst.de/
>
> I think this call can just be removed as you are setting REQ_POLLED
> anyway.
You’re right. I’ll update that in the next version too.

Thanks.

>
>> +		WRITE_ONCE(iocb->private, bio);
>> +	}
>> +
>> +	if (wait_for_completion) {
>> +		sr->waiter = current;
>> +		blk_crypto_submit_bio(bio);
>> +	} else {
>> +		atomic_set(&sr->state, IOMAP_DIO_SIMPLE_SUBMITTING);
>> +		sr->waiter = NULL;
>> +		blk_crypto_submit_bio(bio);
>> +		ret = -EIOCBQUEUED;
>> +	}
>> +
> --
> Pankaj