John Garry <john.g.garry@xxxxxxxxxx> writes:
> Help explain the code.
>
> Also clarify the comment for bio size check.
Looks good to me. Feel free to add:
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx>
>
> Signed-off-by: John Garry <john.g.garry@xxxxxxxxxx>
> ---
> fs/iomap/direct-io.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
> index 8c1bec473586..b9f59ca43c15 100644
> --- a/fs/iomap/direct-io.c
> +++ b/fs/iomap/direct-io.c
> @@ -350,6 +350,11 @@ static int iomap_dio_bio_iter(struct iomap_iter *iter, struct iomap_dio *dio)
> bio_opf |= REQ_OP_WRITE;
>
> if (iter->flags & IOMAP_ATOMIC_HW) {
> + /*
> + * Ensure that the mapping covers the full write
> + * length, otherwise it won't be submitted as a single
> + * bio, which is required to use hardware atomics.
> + */
> if (length != iter->len)
> return -EINVAL;
> bio_opf |= REQ_ATOMIC;
> @@ -449,7 +454,7 @@ static int iomap_dio_bio_iter(struct iomap_iter *iter, struct iomap_dio *dio)
> n = bio->bi_iter.bi_size;
> if (WARN_ON_ONCE((bio_opf & REQ_ATOMIC) && n != length)) {
> /*
> - * This bio should have covered the complete length,
> + * An atomic write bio must cover the complete length,
> * which it doesn't, so error. We may need to zero out
> * the tail (complete FS block), similar to when
> * bio_iov_iter_get_pages() returns an error, above.
> --
> 2.31.1
