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Re: [PATCH v1 0/8] VFS: In-kernel copy system call
From: |
Chris Mason |
Subject: |
Re: [PATCH v1 0/8] VFS: In-kernel copy system call |
Date: |
Wed, 9 Sep 2015 16:09:21 -0400 |
User-agent: |
Mutt/1.5.23.1 (2014-03-12) |
On Tue, Sep 08, 2015 at 04:08:43PM -0700, Andy Lutomirski wrote:
> On Tue, Sep 8, 2015 at 3:39 PM, Darrick J. Wong <address@hidden> wrote:
> > On Tue, Sep 08, 2015 at 02:45:39PM -0700, Andy Lutomirski wrote:
> >> What I meant by this was: if you ask for "regular copy", you may end
> >> up with a reflink anyway. Anyway, how can you reflink a range and
> >> have the contents *not* be the same?
> >
> > reflink forcibly remaps fd_dest's range to fd_src's range. If they didn't
> > match before, they will afterwards.
> >
> > dedupe remaps fd_dest's range to fd_src's range only if they match, of
> > course.
> >
> > Perhaps I should have said "...if the contents are the same before the
> > call"?
> >
>
> Oh, I see.
>
> Can we have a clean way to figure out whether two file ranges are the
> same in a way that allows false negatives? I.e. return 1 if the
> ranges are reflinks of each other and 0 if not? Pretty please? I've
> implemented that in the past on btrfs by syncing the ranges and then
> comparing FIEMAP output, but that's hideous.
I'd almost rather have a separate call, maybe unshare_file_range()?
Is that the end goal to the sharing check?
-chris
- Fwd: [PATCH v1 0/8] VFS: In-kernel copy system call, Pádraig Brady, 2015/09/08
- Re: [PATCH v1 0/8] VFS: In-kernel copy system call, Pádraig Brady, 2015/09/08
- Re: [PATCH v1 0/8] VFS: In-kernel copy system call, Darrick J. Wong, 2015/09/08
- Re: [PATCH v1 0/8] VFS: In-kernel copy system call, Andy Lutomirski, 2015/09/08
- Re: [PATCH v1 0/8] VFS: In-kernel copy system call, Darrick J. Wong, 2015/09/08
- Re: [PATCH v1 0/8] VFS: In-kernel copy system call, Andy Lutomirski, 2015/09/08
- Re: [PATCH v1 0/8] VFS: In-kernel copy system call, Darrick J. Wong, 2015/09/08
- Re: [PATCH v1 0/8] VFS: In-kernel copy system call,
Chris Mason <=
- Re: [PATCH v1 0/8] VFS: In-kernel copy system call, Trond Myklebust, 2015/09/09
- Re: [PATCH v1 0/8] VFS: In-kernel copy system call, Chris Mason, 2015/09/09
- Re: [PATCH v1 0/8] VFS: In-kernel copy system call, Anna Schumaker, 2015/09/09
- Re: [PATCH v1 0/8] VFS: In-kernel copy system call, Darrick J. Wong, 2015/09/09
- Re: [PATCH v1 0/8] VFS: In-kernel copy system call, Andy Lutomirski, 2015/09/09
- Re: [PATCH v1 0/8] VFS: In-kernel copy system call, Chris Mason, 2015/09/09
- Re: [PATCH v1 0/8] VFS: In-kernel copy system call, Dave Chinner, 2015/09/13
- Re: [PATCH v1 0/8] VFS: In-kernel copy system call, Andy Lutomirski, 2015/09/14
- Re: [PATCH v1 0/8] VFS: In-kernel copy system call, Anna Schumaker, 2015/09/09
- Re: [PATCH v1 0/8] VFS: In-kernel copy system call, Darrick J. Wong, 2015/09/09