[PATCHv3 2/5] block: bio-integrity: directly map user buffers
Christoph Hellwig
hch at lst.de
Mon Nov 20 21:04:38 PST 2023
On Mon, Nov 20, 2023 at 02:40:55PM -0800, Keith Busch wrote:
> +static void bio_integrity_unmap_user(struct bio_integrity_payload *bip)
> +{
> + bool dirty = bio_data_dir(bip->bip_bio) == READ;
> + struct bvec_iter iter;
> + struct bio_vec bv;
> +
> + if (bip->bip_flags & BIP_COPY_USER) {
> + unsigned short nr_vecs = bip->bip_max_vcnt - 1;
> + struct bio_vec *copy = bvec_virt(&bip->bip_vec[nr_vecs]);
> + size_t bytes = bip->bip_iter.bi_size;
> + void *buf = bvec_virt(bip->bip_vec);
> +
> + if (dirty) {
> + struct iov_iter iter;
> +
> + iov_iter_bvec(&iter, ITER_DEST, copy, nr_vecs, bytes);
> + WARN_ON_ONCE(copy_to_iter(buf, bytes, &iter) != bytes);
> + }
> +
> + memcpy(bip->bip_vec, copy, nr_vecs * sizeof(*copy));
> + kfree(copy);
> + kfree(buf);
Nit: but I'd probably just split the user copy version into a separate
helper for clarity. Nice trick with the temporary iter, we could probably
use this for the data path too.
> +extern int bio_integrity_map_user(struct bio *, void __user *, ssize_t, u32);
Can you drop the pointless extern and just spell out the paratmeters?
I know this follows the existing style, but that style is pretty
horrible :)
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