linux-ext4 - Re: bug#6131: [PATCH]: fiemap support for efficient sparse file copy

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:	Tue, 15 Jun 2010 14:09:22 -0700
From:	Paul Eggert <eggert@...UCLA.EDU>
To:	"jeff.liu" <jeff.liu@...cle.com>
CC:	Sunil Mushran <sunil.mushran@...cle.com>,
	Jim Meyering <jim@...ering.net>, bug-coreutils@....org,
	Joel Becker <Joel.Becker@...cle.com>,
	Chris Mason <chris.mason@...cle.com>,
	"linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>,
	Tao Ma <tao.ma@...cle.com>
Subject: Re: bug#6131: [PATCH]: fiemap support for efficient sparse file copy

On 06/11/2010 01:31 AM, jeff.liu wrote:

> +      fiemap->fm_flags = FIEMAP_FLAG_SYNC;

If I'm reading the Linux source code correctly,
this forces all the dirty blocks in the input file to disk, and
forces the kernel to wait until all those blocks actually hit the disk.
We don't need that; there shouldn't be a need to force any
blocks to hit the disk.  All that 'cp' needs to know is: please tell me
the next block which might contain nonzero data.  Is there some way
that we can get that information without forcing the input file's
blocks to disk?
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html