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From: Amir Goldstein <amir73il@gmail.com>
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: Dave Chinner <david@fromorbit.com>,
	linux-xfs <linux-xfs@vger.kernel.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Linux Btrfs <linux-btrfs@vger.kernel.org>,
	ocfs2-devel@oss.oracle.com, Eric Sandeen <sandeen@redhat.com>
Subject: Re: [PATCH 12/15] vfs: implement opportunistic short dedupe
Date: Fri, 5 Oct 2018 09:40:44 +0300	[thread overview]
Message-ID: <CAOQ4uxgqQ9ovr1i5+uGz1hq=fedFGKK7TpPCUvXkYPXhoPji3g@mail.gmail.com> (raw)
In-Reply-To: <153870036143.29072.11970142092673351715.stgit@magnolia>

On Fri, Oct 5, 2018 at 3:46 AM Darrick J. Wong <darrick.wong@oracle.com> wrote:
>
> From: Darrick J. Wong <darrick.wong@oracle.com>
>
> For a given dedupe request, the bytes_deduped field in the control
> structure tells userspace if we managed to deduplicate some, but not all
> of, the requested regions starting from the file offsets supplied.
> However, due to sloppy coding, the current dedupe code returns
> FILE_DEDUPE_RANGE_DIFFERS if any part of the range is different.
> Fix this so that we can actually support partial request completion.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
>  fs/read_write.c    |   44 +++++++++++++++++++++++++++++++++++---------
>  include/linux/fs.h |    2 +-
>  2 files changed, 36 insertions(+), 10 deletions(-)
>
>
> diff --git a/fs/read_write.c b/fs/read_write.c
> index 292d68c2f47c..9be9f261edd2 100644
> --- a/fs/read_write.c
> +++ b/fs/read_write.c
> @@ -1781,13 +1781,11 @@ int vfs_clone_file_prep(struct file *file_in, loff_t pos_in,
>          * Check that the extents are the same.
>          */
>         if (is_dedupe) {
> -               bool            is_same = false;
> -
>                 ret = vfs_dedupe_file_range_compare(inode_in, pos_in,
> -                               inode_out, pos_out, *len, &is_same);
> +                               inode_out, pos_out, len);
>                 if (ret)
>                         return ret;
> -               if (!is_same)
> +               if (*len == 0)
>                         return -EBADE;
>         }
>
> @@ -1872,13 +1870,30 @@ static struct page *vfs_dedupe_get_page(struct inode *inode, loff_t offset)
>         return page;
>  }
>
> +static unsigned int vfs_dedupe_memcmp(const char *s1, const char *s2,
> +                                     unsigned int cmp_len)
> +{
> +       const char *orig_s1 = s1;
> +       const char *e1 = s1 + cmp_len;
> +       const char *e2 = s2 + cmp_len;
> +
> +       while (s1 < e1 && s2 < e2) {
> +               if (*s1 != *s2)
> +                       break;
> +               s1++;
> +               s2++;
> +       }
> +
> +       return s1 - orig_s1;
> +}
> +

A few nits:
'len' wouldn't have been ambiguous in this context.
I find the for loop in memcmp more elegant. It is definitely shorter.
Not sure how differently the variants compile, but decrementing
count/len seems much more sane then checking 2 conditions that
always have the same result.

Thanks,
Amir.

  reply	other threads:[~2018-10-05  6:40 UTC|newest]

Thread overview: 82+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-05  0:44 [PATCH 00/15] fs: fixes for serious clone/dedupe problems Darrick J. Wong
2018-10-05  0:44 ` [Ocfs2-devel] " Darrick J. Wong
2018-10-05  0:44 ` [PATCH 01/15] xfs: add a per-xfs trace_printk macro Darrick J. Wong
2018-10-05  0:44   ` [Ocfs2-devel] " Darrick J. Wong
2018-10-05  0:44 ` [PATCH 02/15] xfs: refactor clonerange preparation into a separate helper Darrick J. Wong
2018-10-05  0:44   ` [Ocfs2-devel] " Darrick J. Wong
2018-10-05  5:28   ` Dave Chinner
2018-10-05  5:28     ` [Ocfs2-devel] " Dave Chinner
2018-10-05 17:06     ` Darrick J. Wong
2018-10-05 17:06       ` [Ocfs2-devel] " Darrick J. Wong
2018-10-06 10:30     ` Christoph Hellwig
2018-10-06 10:30       ` [Ocfs2-devel] " Christoph Hellwig
2018-10-05  7:02   ` Dave Chinner
2018-10-05  7:02     ` [Ocfs2-devel] " Dave Chinner
2018-10-05  9:02     ` Dave Chinner
2018-10-05  9:02       ` [Ocfs2-devel] " Dave Chinner
2018-10-05 17:21       ` Darrick J. Wong
2018-10-05 17:21         ` [Ocfs2-devel] " Darrick J. Wong
2018-10-05 23:42         ` Dave Chinner
2018-10-05 23:42           ` [Ocfs2-devel] " Dave Chinner
2018-10-05  0:44 ` [PATCH 03/15] xfs: zero posteof blocks when cloning above eof Darrick J. Wong
2018-10-05  0:44   ` [Ocfs2-devel] " Darrick J. Wong
2018-10-05  5:28   ` Dave Chinner
2018-10-05  5:28     ` [Ocfs2-devel] " Dave Chinner
2018-10-06 10:34   ` Christoph Hellwig
2018-10-06 10:34     ` [Ocfs2-devel] " Christoph Hellwig
2018-10-05  0:45 ` [PATCH 04/15] xfs: update ctime and remove suid before cloning files Darrick J. Wong
2018-10-05  0:45   ` [Ocfs2-devel] " Darrick J. Wong
2018-10-05  5:30   ` Dave Chinner
2018-10-05  5:30     ` [Ocfs2-devel] " Dave Chinner
2018-10-06 10:35   ` Christoph Hellwig
2018-10-06 10:35     ` [Ocfs2-devel] " Christoph Hellwig
2018-10-05  0:45 ` [PATCH 05/15] vfs: check file ranges " Darrick J. Wong
2018-10-05  0:45   ` [Ocfs2-devel] " Darrick J. Wong
2018-10-06 10:38   ` Christoph Hellwig
2018-10-06 10:38     ` [Ocfs2-devel] " Christoph Hellwig
2018-10-05  0:45 ` [PATCH 06/15] vfs: strengthen checking of file range inputs to clone/dedupe range Darrick J. Wong
2018-10-05  0:45   ` [Ocfs2-devel] " Darrick J. Wong
2018-10-05  6:10   ` Amir Goldstein
2018-10-05 17:36     ` Darrick J. Wong
2018-10-05 17:36       ` [Ocfs2-devel] " Darrick J. Wong
2018-10-05  0:45 ` [PATCH 07/15] vfs: skip zero-length dedupe requests Darrick J. Wong
2018-10-05  0:45   ` [Ocfs2-devel] " Darrick J. Wong
2018-10-05  8:39   ` Amir Goldstein
2018-10-06 10:39   ` Christoph Hellwig
2018-10-06 10:39     ` [Ocfs2-devel] " Christoph Hellwig
2018-10-05  0:45 ` [PATCH 08/15] vfs: change clone and dedupe range function pointers to return bytes completed Darrick J. Wong
2018-10-05  0:45   ` [Ocfs2-devel] " Darrick J. Wong
2018-10-05  8:06   ` Amir Goldstein
2018-10-05 21:47     ` Darrick J. Wong
2018-10-05 21:47       ` [Ocfs2-devel] " Darrick J. Wong
2018-10-06 10:41   ` Christoph Hellwig
2018-10-06 10:41     ` [Ocfs2-devel] " Christoph Hellwig
2018-10-08 18:59     ` Darrick J. Wong
2018-10-08 18:59       ` [Ocfs2-devel] " Darrick J. Wong
2018-10-05  0:45 ` [PATCH 09/15] vfs: pass operation flags to {clone, dedupe}_file_range implementations Darrick J. Wong
2018-10-05  0:45   ` [Ocfs2-devel] " Darrick J. Wong
2018-10-05  7:07   ` Amir Goldstein
2018-10-05 17:50     ` Darrick J. Wong
2018-10-05 17:50       ` [Ocfs2-devel] " Darrick J. Wong
2018-10-06 10:44       ` Christoph Hellwig
2018-10-06 10:44         ` [Ocfs2-devel] " Christoph Hellwig
2018-10-05  0:45 ` [PATCH 10/15] vfs: make cloning to source file eof more explicit Darrick J. Wong
2018-10-05  0:45   ` [Ocfs2-devel] " Darrick J. Wong
2018-10-05  6:47   ` Amir Goldstein
2018-10-05  0:45 ` [PATCH 11/15] vfs: allow short clone and dedupe operations Darrick J. Wong
2018-10-05  0:45   ` [Ocfs2-devel] " Darrick J. Wong
2018-10-05  0:46 ` [PATCH 12/15] vfs: implement opportunistic short dedupe Darrick J. Wong
2018-10-05  0:46   ` [Ocfs2-devel] " Darrick J. Wong
2018-10-05  6:40   ` Amir Goldstein [this message]
2018-10-05 17:42     ` Darrick J. Wong
2018-10-05 17:42       ` [Ocfs2-devel] " Darrick J. Wong
2018-10-05  0:46 ` [PATCH 13/15] ocfs2: truncate page cache for clone destination file before remapping Darrick J. Wong
2018-10-05  0:46   ` [Ocfs2-devel] " Darrick J. Wong
2018-10-05  0:46 ` [PATCH 14/15] ocfs2: support partial clone range and dedupe range Darrick J. Wong
2018-10-05  0:46   ` [Ocfs2-devel] " Darrick J. Wong
2018-10-05  0:46 ` [PATCH 15/15] xfs: support returning partial reflink results Darrick J. Wong
2018-10-05  0:46   ` [Ocfs2-devel] " Darrick J. Wong
2018-10-05  1:17 ` [PATCH 00/15] fs: fixes for serious clone/dedupe problems Dave Chinner
2018-10-05  1:17   ` [Ocfs2-devel] " Dave Chinner
2018-10-05  1:24   ` Darrick J. Wong
2018-10-05  1:24     ` [Ocfs2-devel] " Darrick J. Wong

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