From: Andreas Dilger <adilger@sun.com>
To: Florian Weimer <fw@deneb.enyo.de>
Cc: linux-fsdevel@vger.kernel.org
Subject: Re: FIBMAP/FIEMAP discrepancy for CAP_SYS_RAWIO
Date: Mon, 07 Sep 2009 12:50:14 +0200 [thread overview]
Message-ID: <20090907105014.GV4197@webber.adilger.int> (raw)
In-Reply-To: <87y6osry4k.fsf@mid.deneb.enyo.de>
On Sep 06, 2009 13:39 +0000, Florian Weimer wrote:
> The FIBMAP ioctl requires CAP_SYS_RAWIO, but FIEMAP doesn't. Why's
> that? Is it that there is no backwards-compatible way to introduce
> locking on the bmap path?
I'm not sure why there is a root-only requirement for FIBMAP, but the
FIEMAP data is definitely useful even for non-root users for many
reasons, such as optimized file copies/rsync/tar/etc skipping holes
in sparse files easily.
If you are implementing a tool to use this, I would code it to try
FIEMAP first, then FIBMAP (if it is running as root, or it gets
fixed in some future kernel), then just do without (as it most likely
does already today).
Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.
next prev parent reply other threads:[~2009-09-07 10:50 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-06 13:39 FIBMAP/FIEMAP discrepancy for CAP_SYS_RAWIO Florian Weimer
2009-09-07 10:50 ` Andreas Dilger [this message]
2009-09-07 13:28 ` Theodore Tso
2009-09-07 16:26 ` Florian Weimer
2009-09-08 7:23 ` Andreas Dilger
2009-09-08 8:47 ` Jamie Lokier
2009-09-09 16:13 ` Andreas Dilger
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