linux-kernel - Re: [patch]block: add plug for blkdev_issue

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 8 Oct 2012 21:56:35 -0400
From:	Mike Snitzer <snitzer@...hat.com>
To:	Shaohua Li <shli@...nel.org>
Cc:	axboe@...nel.dk, linux-kernel@...r.kernel.org
Subject: Re: [patch]block: add plug for blkdev_issue_discard

On Mon, Oct 8, 2012 at 9:11 PM, Shaohua Li <shli@...nel.org> wrote:
> Now discard merge works, add plug for blkdev_issue_discard. This will help
> discard request merge especially for raid0 case. In raid0, a big discard
> request is split to small requests, and if correct plug is added, such small
> requests can be merged in low layer.
>
> Signed-off-by: Shaohua Li <shli@...ionio.com>
> ---
>  block/blk-lib.c |    3 +++
>  1 file changed, 3 insertions(+)
>
> Index: linux/block/blk-lib.c
> ===================================================================
> --- linux.orig/block/blk-lib.c  2012-09-28 15:09:38.655327319 +0800
> +++ linux/block/blk-lib.c       2012-10-09 08:45:04.358598888 +0800
> @@ -48,6 +48,7 @@ int blkdev_issue_discard(struct block_de
>         struct bio_batch bb;
>         struct bio *bio;
>         int ret = 0;
> +       struct blk_plug plug;
>
>         if (!q)
>                 return -ENXIO;
> @@ -81,6 +82,7 @@ int blkdev_issue_discard(struct block_de
>         bb.flags = 1 << BIO_UPTODATE;
>         bb.wait = &wait;
>
> +       blk_start_plug(&plug);
>         while (nr_sects) {
>                 unsigned int req_sects;
>                 sector_t end_sect;
> @@ -117,6 +119,7 @@ int blkdev_issue_discard(struct block_de
>                 atomic_inc(&bb.done);
>                 submit_bio(type, bio);
>         }
> +       blk_finish_plug(&plug);
>
>         /* Wait for bios in-flight */
>         if (!atomic_dec_and_test(&bb.done))

That plug looks rather coarse-grained.  Any adverse affects when mkfs
discards an entire (large) raid0 device?  (I suspect not but figured
I'd ask)
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/