From: Dave Chinner <david@fromorbit.com>
To: Theodore Tso <tytso@MIT.EDU>
Cc: "Andreas Dilger" <adilger@dilger.ca>,
"Pádraig Brady" <P@draigBrady.com>,
"Eric Sandeen" <sandeen@sandeen.net>,
"linux-ext4@vger.kernel.org" <linux-ext4@vger.kernel.org>,
"coreutils@gnu.org" <coreutils@gnu.org>,
"Markus Trippelsdorf" <markus@trippelsdorf.de>,
xfs-oss <xfs@oss.sgi.com>
Subject: Re: Files full of zeros with coreutils-8.11 and xfs (FIEMAP related?)
Date: Mon, 18 Apr 2011 10:40:40 +1000 [thread overview]
Message-ID: <20110418004040.GS21395@dastard> (raw)
In-Reply-To: <4EEEA16E-1FDB-4430-A372-8F8701196E4C@mit.edu>
On Sat, Apr 16, 2011 at 08:21:28AM -0400, Theodore Tso wrote:
>
> On Apr 16, 2011, at 1:11 AM, Andreas Dilger wrote:
>
> > In that case, it means cp should just always use FIEMAP_FLAG_SYNC, which is fine.
>
> Except that if someone is copying a large delay allocated file, it will cause
> the file to immediately snapped to disk, which might not be the greatest
> thing in the world.
Obvious workaround - if the initial fiemap call shows unwritten
extents, redo it with the sync flag set. Though that assumeѕ that
you can trust things like delalloc extents to only cover the range
that valid data exists in. Which, of course, you can't assume,
either. :/
> Christoph is write, SEEK_HOLE and SEEK_DATA are
> a much better API for what cp woulld lke to do. Unfortunately it hasn't
> been implemented yet in the VFS...
Agreed, SEEK_HOLE/SEEK_DATA is the right way to solve this problem.
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
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next prev parent reply other threads:[~2011-04-18 0:40 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20110414102608.GA1678@x4.trippels.de>
[not found] ` <20110414120635.GB1678@x4.trippels.de>
[not found] ` <20110414140222.GB1679@x4.trippels.de>
[not found] ` <20110414140222.GB1679-tLCgZGx+iJ+kxVt8IV0GqQ@public.gmane.org>
2011-04-14 14:59 ` Files full of zeros with coreutils-8.11 and xfs (FIEMAP related?) Pádraig Brady
[not found] ` <4DA70BD3.1070409-V8g9lnOeT5ydJdNcDFJN0w@public.gmane.org>
2011-04-14 15:50 ` Eric Sandeen
[not found] ` <4DA717B2.3020305-+82itfer+wXR7s880joybQ@public.gmane.org>
2011-04-14 15:52 ` Pádraig Brady
2011-04-14 15:56 ` Eric Sandeen
2011-04-14 16:03 ` Markus Trippelsdorf
2011-04-14 16:14 ` Eric Sandeen
[not found] ` <20110414160343.GA12787-tLCgZGx+iJ+kxVt8IV0GqQ@public.gmane.org>
2011-04-14 16:21 ` Yongqiang Yang
[not found] ` <BANLkTimRxvBMp9M7zwiUY_UmmFOY5N58+A-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-04-14 16:28 ` Markus Trippelsdorf
2011-04-14 16:31 ` Eric Sandeen
2011-04-14 16:48 ` Markus Trippelsdorf
2011-04-14 16:49 ` Eric Sandeen
2011-04-14 16:04 ` Yongqiang Yang
2011-04-14 16:10 ` Yongqiang Yang
[not found] ` <BANLkTimoLeWMJgNFGW+zdeUeJyZ-_+8fMQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-05-05 11:29 ` Pádraig Brady
2011-05-05 11:47 ` Yongqiang Yang
[not found] ` <4DA7182B.8050409-V8g9lnOeT5ydJdNcDFJN0w@public.gmane.org>
2011-04-14 17:27 ` Jim Meyering
2011-04-14 19:13 ` Pádraig Brady
[not found] ` <878vvcspz0.fsf-CybKA8TIZ99x3y/oJEDuiw@public.gmane.org>
2011-04-14 19:39 ` Jim Meyering
2011-04-14 22:59 ` Dave Chinner
2011-04-14 23:29 ` Pádraig Brady
2011-04-15 0:09 ` Dave Chinner
2011-04-15 5:01 ` Andreas Dilger
2011-04-16 0:50 ` Dave Chinner
2011-04-16 5:11 ` Andreas Dilger
2011-04-16 12:21 ` Theodore Tso
2011-04-18 0:40 ` Dave Chinner [this message]
2011-04-18 2:45 ` Andreas Dilger
2011-04-19 1:58 ` Yongqiang Yang
[not found] ` <BANLkTin=WEpSf6ddiOMNMOpCPP-wiEttSw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-04-19 2:59 ` Ted Ts'o
[not found] ` <20110419025949.GA3030-AKGzg7BKzIDYtjvyW6yDsg@public.gmane.org>
2011-04-19 3:05 ` Eric Sandeen
[not found] ` <4DACFBEB.9040909-+82itfer+wXR7s880joybQ@public.gmane.org>
2011-04-21 20:12 ` Jim Meyering
2011-04-19 3:30 ` Yongqiang Yang
2011-04-19 4:14 ` Dave Chinner
2011-04-19 5:27 ` Christoph Hellwig
2011-04-19 3:44 ` Dave Chinner
2011-04-19 6:53 ` Yongqiang Yang
2011-04-19 7:45 ` Dave Chinner
2011-04-19 8:11 ` Yongqiang Yang
2011-04-19 14:05 ` Eric Sandeen
2011-04-19 14:09 ` Ted Ts'o
2011-04-19 14:13 ` Eric Sandeen
2011-04-19 16:01 ` Ted Ts'o
2011-04-20 1:53 ` Yongqiang Yang
2011-04-20 15:21 ` Christoph Hellwig
2011-04-20 17:21 ` Ted Ts'o
[not found] ` <20110419140909.GD3030-AKGzg7BKzIDYtjvyW6yDsg@public.gmane.org>
2011-04-19 21:08 ` Dave Chinner
2011-04-20 15:29 ` Christoph Hellwig
2011-04-16 6:05 ` Yongqiang Yang
2011-04-18 0:35 ` Dave Chinner
2011-04-15 8:53 ` Jim Meyering
2011-04-15 17:16 ` Christoph Hellwig
[not found] ` <20110415171629.GA9088-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2011-04-15 17:24 ` Eric Blake
2011-04-15 17:26 ` Christoph Hellwig
[not found] ` <20110415172603.GA20086-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2011-04-15 22:28 ` Andreas Dilger
2011-04-16 0:25 ` Dave Chinner
[not found] ` <20110414102608.GA1678-tLCgZGx+iJ+kxVt8IV0GqQ@public.gmane.org>
2011-04-20 14:39 ` Jim Meyering
[not found] ` <87d3khugv1.fsf-CybKA8TIZ99x3y/oJEDuiw@public.gmane.org>
2011-04-21 20:01 ` Jim Meyering
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