From: Ming Lei <ming.lei@redhat.com>
To: Bart Van Assche <bvanassche@acm.org>
Cc: Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
stable@vger.kernel.org
Subject: Re: [PATCH 4/5] block: Fix zero_fill_bio()
Date: Sat, 16 May 2020 13:50:12 +0800 [thread overview]
Message-ID: <20200516055012.GA3393@T590> (raw)
In-Reply-To: <20200516001914.17138-5-bvanassche@acm.org>
On Fri, May 15, 2020 at 05:19:13PM -0700, Bart Van Assche wrote:
> Multiple block drivers use zero_fill_bio() to zero-initialize the data
> buffer used for read operations. Make sure that all pages are zeroed
> instead of only the first if one or more multi-page bvecs are used to
> describe the data buffer.
>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Ming Lei <ming.lei@redhat.com>
> Cc: stable@vger.kernel.org
> Signed-off-by: Bart Van Assche <bvanassche@acm.org>
> ---
> block/bio.c | 27 ++++++++++++++++++++++-----
> include/linux/bio.h | 1 +
> 2 files changed, 23 insertions(+), 5 deletions(-)
>
> diff --git a/block/bio.c b/block/bio.c
> index 1594804fe8bc..48fcafbdae70 100644
> --- a/block/bio.c
> +++ b/block/bio.c
> @@ -527,17 +527,34 @@ struct bio *bio_alloc_bioset(gfp_t gfp_mask, unsigned int nr_iovecs,
> }
> EXPORT_SYMBOL(bio_alloc_bioset);
>
> +void zero_fill_bvec(const struct bio_vec *bvec)
> +{
> + struct page *page = bvec->bv_page;
> + u32 offset = bvec->bv_offset;
> + u32 left = bvec->bv_len;
> +
> + while (left) {
> + u32 len = min_t(u32, left, PAGE_SIZE - offset);
> + void *kaddr;
> +
> + kaddr = kmap_atomic(page);
> + memset(kaddr + offset, 0, len);
> + flush_dcache_page(page);
> + kunmap_atomic(kaddr);
> + page++;
> + left -= len;
> + offset = 0;
> + }
> +}
> +EXPORT_SYMBOL(zero_fill_bvec);
> +
> void zero_fill_bio_iter(struct bio *bio, struct bvec_iter start)
> {
> - unsigned long flags;
> struct bio_vec bv;
> struct bvec_iter iter;
>
> __bio_for_each_segment(bv, bio, iter, start) {
The 'bv' from __bio_for_each_segment() is single page bvec, and so far
only [__]bio_for_each_bvec iterates over multi-page bvec.
So nothing to be fixed and this patch isn't necessary.
Thanks,
Ming
next prev parent reply other threads:[~2020-05-16 5:50 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-16 0:19 [PATCH 0/5] Block layer patches for kernel v5.8 Bart Van Assche
2020-05-16 0:19 ` [PATCH 1/5] block: Fix type of first compat_put_{,u}long() argument Bart Van Assche
2020-05-16 7:40 ` Arnd Bergmann
2020-05-16 12:41 ` Christoph Hellwig
2020-05-16 0:19 ` [PATCH 2/5] bio.h: Declare the arguments of bio iteration functions const Bart Van Assche
2020-05-16 8:55 ` Alexander Potapenko
2020-05-16 17:10 ` Bart Van Assche
2020-05-16 12:42 ` Christoph Hellwig
2020-05-17 22:46 ` Chaitanya Kulkarni
2020-05-16 0:19 ` [PATCH 3/5] block: Document the bio_vec properties Bart Van Assche
2020-05-16 12:43 ` Christoph Hellwig
2020-05-16 0:19 ` [PATCH 4/5] block: Fix zero_fill_bio() Bart Van Assche
2020-05-16 5:50 ` Ming Lei [this message]
2020-05-16 0:19 ` [PATCH 5/5] null_blk: Zero-initialize read buffers in non-memory-backed mode Bart Van Assche
2020-05-16 9:40 ` Alexander Potapenko
2020-05-18 1:12 ` Damien Le Moal
2020-05-18 1:32 ` Bart Van Assche
2020-05-18 2:10 ` Damien Le Moal
2020-05-18 2:56 ` Bart Van Assche
2020-05-18 3:12 ` Damien Le Moal
2020-05-18 14:31 ` Bart Van Assche
2020-05-19 3:03 ` Damien Le Moal
2020-05-19 4:10 ` Bart Van Assche
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200516055012.GA3393@T590 \
--to=ming.lei@redhat.com \
--cc=axboe@kernel.dk \
--cc=bvanassche@acm.org \
--cc=hch@lst.de \
--cc=linux-block@vger.kernel.org \
--cc=stable@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).