On Sat, Mar 25, 2017 at 6:20 AM, Shaohua Li <shli@xxxxxx> wrote:
> discard request doesn't have data attached, so it's meaningless to
> allocate memory and copy from original bio for behind IO. And the copy
> is bogus because bio_copy_data_partial can't handle discard request.
>
> We don't support writesame/writezeros request so far.
>
> Cc: Ming Lei <tom.leiming@xxxxxxxxx>
> Signed-off-by: Shaohua Li <shli@xxxxxx>
Another way is to not do write behind for discard, but both should be fine, so:
Reviewed-by: Ming Lei <tom.leiming@xxxxxxxxx>
> ---
> drivers/md/raid1.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> index c6a671f..b7d9651 100644
> --- a/drivers/md/raid1.c
> +++ b/drivers/md/raid1.c
> @@ -1102,6 +1102,10 @@ static struct bio *alloc_behind_master_bio(struct r1bio *r1_bio,
> if (!behind_bio)
> goto fail;
>
> + /* discard op, we don't support writezero/writesame yet */
> + if (!bio_has_data(bio))
> + goto skip_copy;
> +
> while (i < vcnt && size) {
> struct page *page;
> int len = min_t(int, PAGE_SIZE, size);
> @@ -1118,7 +1122,7 @@ static struct bio *alloc_behind_master_bio(struct r1bio *r1_bio,
>
> bio_copy_data_partial(behind_bio, bio, offset,
> behind_bio->bi_iter.bi_size);
> -
> +skip_copy:
> r1_bio->behind_master_bio = behind_bio;;
> set_bit(R1BIO_BehindIO, &r1_bio->state);
>
> --
> 2.9.3
>
--
Ming Lei
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