GNU bug report logs - #6131
[PATCH]: fiemap support for efficient sparse file copy

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Message #344 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Jim Meyering <jim <at> meyering.net>
To: Pádraig Brady <P <at> draigBrady.com>
Cc: Sunil Mushran <sunil.mushran <at> oracle.com>, Paul Eggert <eggert <at> cs.ucla.edu>,
	6131-done <at> debbugs.gnu.org, bug-coreutils <at> gnu.org,
	Jeff liu <jeff.liu <at> oracle.com>, Chris Mason <chris.mason <at> oracle.com>
Subject: Re: bug#6131: [PATCH]: fiemap support for efficient sparse file copy
Date: Sun, 30 Jan 2011 21:32:16 +0100

Jim Meyering wrote:
...
> I've amended those two commits, rebased, and pushed to
> a new branch: fiemap-copy-3.

As I mentioned, everything is now on "master".
Odd how that works.  Minutes after pushing everything,
I wondered if there was a NEWS entry for this feature...
No.  So I wrote this:

From 5b11cd01790473b1964a0f91eca5205dfdcae773 Mon Sep 17 00:00:00 2001
From: Jim Meyering <meyering <at> redhat.com>
Date: Sun, 30 Jan 2011 21:27:12 +0100
Subject: [PATCH] doc: NEWS: mention cp's improvement

* NEWS (New Features): cp now copies sparse files efficiently.
---
 NEWS |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/NEWS b/NEWS
index 6e7efe1..042bfed 100644
--- a/NEWS
+++ b/NEWS
@@ -21,6 +21,15 @@ GNU coreutils NEWS                                    -*- outline -*-

 ** New features

+  cp now copies sparse files efficiently on file systems with FIEMAP
+  support (ext4, btrfs, xfs, ocfs2).  Before, it had to read 2^20 bytes
+  when copying a 1MiB sparse file.  Now, it copies bytes only for the
+  non-sparse sections of a file.  Similarly, to induce a hole in the
+  output file, it had to detect a long sequence of zero bytes.  Now,
+  it knows precisely where each hole in an input file is, and can
+  reproduce them efficiently in the output file.  mv also benefits
+  when it resorts to copying, e.g., between file systems.
+
   join now supports -o 'auto' which will automatically infer the
   output format from the first line in each file, to ensure
   the same number of fields are output for each line.
--
1.7.3.5.44.g960a

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