From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrey Zhadchenko <andrey.zhadchenko@virtuozzo.com>
Date: Wed, 19 Aug 2026 00:57:39 +0200
Subject: Re: [Devel] [PATCH VZ10 4/5] drivers/vhost/blk: fix sector
 alignment calculation
In-Reply-To: <20260818150920.13123-5-andrey.zhadchenko@virtuozzo.com>
References: <20260818150920.13123-1-andrey.zhadchenko@virtuozzo.com>
	<20260818150920.13123-5-andrey.zhadchenko@virtuozzo.com>
Message-ID: <183b3c0d-8031-4cd2-9c7a-8fa6d6cb7af5@virtuozzo.com>
List-Id: <devel.openvz.org>

Actually for v2 I will replace manual calculations with IS_ALIGNED macro 
so we don't step on this again.

On 8/18/26 17:09, Andrey Zhadchenko wrote:
> SECTOR_MASK is actually a number 7, not some bitmask. Hence
> the code actually checked 8 byte alignment.
> Use (SECTOR_SIZE - 1) to correctly check sector alignment.
> 
> https://virtuozzo.atlassian.net/browse/VSTOR-138640
> Fixes: a0d3b8956fb0 ("vhost-blk: rework iov and bio handling")
> Signed-off-by: Andrey Zhadchenko <andrey.zhadchenko@virtuozzo.com>
> ---
>   drivers/vhost/blk.c | 10 +++++-----
>   1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/vhost/blk.c b/drivers/vhost/blk.c
> index 43bc122ff17e3..2f94c987c62d8 100644
> --- a/drivers/vhost/blk.c
> +++ b/drivers/vhost/blk.c
> @@ -209,13 +209,13 @@ inline static bool vhost_blk_iov_need_bb(struct vhost_blk_req *req)
>   {
>   	int i;
>   
> -	if (req->len & SECTOR_MASK)
> +	if (req->len & (SECTOR_SIZE - 1))
>   		return true;
>   
>   	for (i = 0; i < req->iov_nr; i++) {
> -		if (((size_t)req->iov[i].iov_base) & SECTOR_MASK)
> +		if (((size_t)req->iov[i].iov_base) & (SECTOR_SIZE - 1))
>   			return true;
> -		if (req->iov[i].iov_len & SECTOR_MASK)
> +		if (req->iov[i].iov_len & (SECTOR_SIZE - 1))
>   			return true;
>   	}
>   
> @@ -277,7 +277,7 @@ static int vhost_blk_bio_make(struct vhost_blk_req *req,
>   	if (unlikely(req->bi_opf & REQ_PREFLUSH))
>   		return vhost_blk_bio_make_simple(req, bdev);
>   
> -	if (req->bi_opf == REQ_OP_WRITE && req->len & SECTOR_MASK) {
> +	if (req->bi_opf == REQ_OP_WRITE && req->len & (SECTOR_SIZE - 1)) {
>   		WARN_ONCE(1, "vhost-blk: write requests with unaligned len"
>   			  " are not supported, len = %zu", req->len);
>   		return -EINVAL;
> @@ -339,7 +339,7 @@ static int vhost_blk_bio_make(struct vhost_blk_req *req,
>   	nr_pages = bio_iov_vecs_to_alloc(&iter, BIO_MAX_VECS);
>   	do {
>   		/* We can't handle next bio if it's start is not sector aligned */
> -		if (pos & SECTOR_MASK) {
> +		if (pos & (SECTOR_SIZE - 1)) {
>   			WARN_ONCE(1, "vhost-blk: guest provided unaligned buffers");
>   			ret = -EINVAL;
>   			goto err_bio;