From: Anna Schumaker <Anna.Schumaker-HgOvQuBEEgTQT0dZR+AlfA@public.gmane.org>
To: "Pádraig Brady" <P@draigBrady.com>,
linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-btrfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
zab-ugsP4Wv/S6ZeoWH0uzbU5w@public.gmane.org,
viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org,
clm-b10kYP2dOMg@public.gmane.org,
darrick.wong-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org,
mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org,
andros-HgOvQuBEEgTQT0dZR+AlfA@public.gmane.org,
hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org
Subject: Re: [PATCH v1 0/8] VFS: In-kernel copy system call
Date: Tue, 8 Sep 2015 14:23:23 -0400 [thread overview]
Message-ID: <55EF279B.3020101@Netapp.com> (raw)
In-Reply-To: <55EEFCEE.5090000-V8g9lnOeT5ydJdNcDFJN0w@public.gmane.org>
On 09/08/2015 11:21 AM, Pádraig Brady wrote:
> On 04/09/15 21:16, Anna Schumaker wrote:
>> Copy system calls came up during Plumbers a couple of weeks ago, because
>> several filesystems (including NFS and XFS) are currently working on copy
>> acceleration implementations. We haven't heard from Zach Brown in a while,
>> so I volunteered to push his patches upstream so individual filesystems
>> don't need to keep writing their own ioctls.
>
> Just mentioning that this is just pertaining to the data, not the metadata.
> Providing metadata copying facilities would be _very_ useful, as
> most file system specific details relate to the metadata, and having
> VFS operations for that would avoid the plethora of details in each userspace tool,
> and theoretically support translations between disparate metadata.
Metadata copying could be added later if somebody really wants it.
>
>> The first three patches are a simple reposting of Zach's patches from several
>> months ago, with one minor error code fix. The remaining patches add in a
>> fallback mechanism when filesystems don't provide a copy function. This is
>> especially useful when doing a server-side copy on NFS (using the new COPY
>> operation in NFS v4.2). This fallback can be disabled by passing the flag
>> COPY_REFLINK to the system call.
>
> I see copy_file_range() is a reflink() on BTRFS?
> That's a bit surprising, as it avoids the copy completely.
> cp(1) for example considered doing a BTRFS clone by default,
> but didn't due to expectations that users actually wanted
> the data duplicated on disk for resilience reasons,
> and for performance reasons so that write latencies were
> restricted to the copy operation, rather than being
> introduced at usage time as the dest file is CoW'd.
>
> If reflink() is a possibility for copy_file_range()
> then could it be done optionally with a flag?
The idea is that filesystems get to choose how to handle copies in the default case. BTRFS could do a reflink, but NFS could do a server side copy instead. I can change the default behavior to only do a data copy (unless the reflink flag is specified) instead, if that is desirable.
What does everybody think?
Anna
>
> thanks,
> Pádraig
>
next prev parent reply other threads:[~2015-09-08 18:23 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-04 20:16 [PATCH v1 0/8] VFS: In-kernel copy system call Anna Schumaker
2015-09-04 20:16 ` [PATCH v1 2/8] x86: add sys_copy_file_range to syscall tables Anna Schumaker
2015-09-04 20:16 ` [PATCH v1 3/8] btrfs: add .copy_file_range file operation Anna Schumaker
[not found] ` <1441397823-1203-4-git-send-email-Anna.Schumaker-ZwjVKphTwtPQT0dZR+AlfA@public.gmane.org>
2015-09-04 21:02 ` Josef Bacik
2015-09-09 8:39 ` David Sterba
2015-09-04 20:17 ` [PATCH v1 7/8] vfs: Copy should use file_out rather than file_in Anna Schumaker
[not found] ` <1441397823-1203-1-git-send-email-Anna.Schumaker-ZwjVKphTwtPQT0dZR+AlfA@public.gmane.org>
2015-09-04 20:16 ` [PATCH v1 1/9] vfs: add copy_file_range syscall and vfs helper Anna Schumaker
2015-09-04 21:50 ` Darrick J. Wong
2015-09-04 20:16 ` [PATCH v1 4/8] btrfs: Add mountpoint checking during btrfs_copy_file_range Anna Schumaker
2015-09-09 9:18 ` David Sterba
2015-09-09 15:56 ` Anna Schumaker
2015-09-04 20:16 ` [PATCH v1 5/8] vfs: Remove copy_file_range mountpoint checks Anna Schumaker
2015-09-04 20:17 ` [PATCH v1 6/8] vfs: Copy should check len after file open mode Anna Schumaker
2015-09-04 20:17 ` [PATCH v1 8/8] vfs: Fall back on splice if no copy function defined Anna Schumaker
2015-09-04 21:08 ` Darrick J. Wong
[not found] ` <20150904210813.GA30681-PTl6brltDGh4DFYR7WNSRA@public.gmane.org>
2015-09-08 14:57 ` Anna Schumaker
2015-09-04 20:17 ` [PATCH v1 9/8] copy_file_range.2: New page documenting copy_file_range() Anna Schumaker
2015-09-04 21:38 ` Darrick J. Wong
[not found] ` <20150904213856.GC10391-PTl6brltDGh4DFYR7WNSRA@public.gmane.org>
2015-09-04 22:31 ` Andreas Dilger
[not found] ` <95674806-645C-410C-8A4B-A46F03AFFE20-m1MBpc4rdrD3fQ9qLvQP4Q@public.gmane.org>
2015-09-08 15:05 ` Anna Schumaker
2015-09-08 15:04 ` Anna Schumaker
2015-09-08 20:39 ` Darrick J. Wong
2015-09-09 9:16 ` David Sterba
[not found] ` <20150908203918.GB30681-PTl6brltDGh4DFYR7WNSRA@public.gmane.org>
2015-09-09 11:38 ` Austin S Hemmelgarn
2015-09-09 17:17 ` Darrick J. Wong
[not found] ` <20150909171757.GE10391-PTl6brltDGh4DFYR7WNSRA@public.gmane.org>
2015-09-09 17:31 ` Anna Schumaker
[not found] ` <55F06CEC.5040208-ZwjVKphTwtPQT0dZR+AlfA@public.gmane.org>
2015-09-09 18:12 ` Darrick J. Wong
2015-09-09 19:25 ` Anna Schumaker
2015-09-10 15:42 ` David Sterba
[not found] ` <20150910154251.GM8891-1ReQVI26iDCaZKY3DrU6dA@public.gmane.org>
2015-09-10 16:43 ` Darrick J. Wong
2015-09-04 22:25 ` [PATCH v1 0/8] VFS: In-kernel copy system call Andreas Dilger
[not found] ` <4B41043F-5D85-42D6-8F20-2DCC45930EF4-m1MBpc4rdrD3fQ9qLvQP4Q@public.gmane.org>
2015-09-05 8:33 ` Al Viro
[not found] ` <20150905083342.GG22011-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2015-09-08 15:08 ` Anna Schumaker
2015-09-08 20:45 ` Darrick J. Wong
[not found] ` <20150908204517.GC30681-PTl6brltDGh4DFYR7WNSRA@public.gmane.org>
2015-09-08 20:49 ` Anna Schumaker
2015-09-08 15:07 ` Anna Schumaker
2015-09-08 15:21 ` Pádraig Brady
[not found] ` <55EEFCEE.5090000-V8g9lnOeT5ydJdNcDFJN0w@public.gmane.org>
2015-09-08 18:23 ` Anna Schumaker [this message]
[not found] ` <55EF279B.3020101-ZwjVKphTwtPQT0dZR+AlfA@public.gmane.org>
2015-09-08 19:10 ` Andy Lutomirski
[not found] ` <CALCETrXxRB-LXVb+=nkwfj0zEjWuXXTctkSAc9Oec0fgyOQ5Yg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-09-08 20:03 ` Pádraig Brady
[not found] ` <55EF3EFD.3080302-V8g9lnOeT5ydJdNcDFJN0w@public.gmane.org>
2015-09-08 21:29 ` Darrick J. Wong
2015-09-08 21:45 ` Andy Lutomirski
2015-09-08 22:39 ` Darrick J. Wong
2015-09-08 23:08 ` Andy Lutomirski
2015-09-09 1:19 ` Darrick J. Wong
2015-09-09 20:09 ` Chris Mason
[not found] ` <20150909200921.GD9511-DzB2rL6jT1BHfPKRx072akEOCMrvLtNR@public.gmane.org>
2015-09-09 20:26 ` Trond Myklebust
[not found] ` <CAHQdGtTSZ1beMMF4DJv=OuA1j2ww0xzJj3+9HMRAf3UpCCLaZg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-09-09 20:38 ` Chris Mason
[not found] ` <20150909203805.GE9511-DzB2rL6jT1BHfPKRx072akEOCMrvLtNR@public.gmane.org>
2015-09-09 20:41 ` Anna Schumaker
[not found] ` <55F0997E.1040105-ZwjVKphTwtPQT0dZR+AlfA@public.gmane.org>
2015-09-09 21:42 ` Darrick J. Wong
2015-09-09 20:37 ` Andy Lutomirski
[not found] ` <CALCETrXPcxHWGwqhtkGStVabWDOsRbBy+VzrN+XxVZA_F9O0qA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-09-09 20:42 ` Chris Mason
[not found] ` <CALCETrVsWBdqvAgwxHcG=gbcWRNPG2ZziWUg1g=siKDrDu7S2Q-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-09-13 23:25 ` Dave Chinner
2015-09-14 17:53 ` Andy Lutomirski
2015-09-09 18:52 ` Anna Schumaker
[not found] ` <55F07FD8.4020507-ZwjVKphTwtPQT0dZR+AlfA@public.gmane.org>
2015-09-09 21:16 ` Darrick J. Wong
2015-09-10 15:10 ` Anna Schumaker
[not found] ` <55F19D7F.5090907-ZwjVKphTwtPQT0dZR+AlfA@public.gmane.org>
2015-09-10 15:49 ` Austin S Hemmelgarn
2015-09-10 11:40 ` Austin S Hemmelgarn
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