From: Jeff Mahoney Subject: Re: [RFC] add FIEMAP ioctl to efficiently map file allocation Date: Fri, 13 Apr 2007 10:53:50 -0400 Message-ID: <461F997E.30002@suse.com> References: <20070412110550.GM5967@schatzie.adilger.int> <97211C89-1810-4B22-B2F4-9D206D43C1F6@cam.ac.uk> <20070413040156.GU5967@schatzie.adilger.int> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit To: Anton Altaparmakov , linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, xfs@oss.sgi.com, hch@infradead.org Return-path: In-Reply-To: <20070413040156.GU5967@schatzie.adilger.int> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Andreas Dilger wrote: > On Apr 12, 2007 12:22 +0100, Anton Altaparmakov wrote: >> This would say that the offset on disk can move at any time or that >> the data is compressed or encrypted on disk thus the data is not >> useful for direct disk access. > > This makes sense. Even for Reiserfs the same is true with packed tails, > and I believe if FIBMAP is called on a tail it will migrate the tail into > a block because this is might be a sign that the file is a kernel that > LILO wants to boot. Actually, reiserfs_aop_bmap() returns 0 when the requested block is in a tail. There's a separate ioctl for unpacking them. - -Jeff - -- Jeff Mahoney SUSE Labs -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (GNU/Linux) Comment: Using GnuPG with SUSE - http://enigmail.mozdev.org iD8DBQFGH5l+LPWxlyuTD7IRAn5/AJ9VcocIcDGr9wtAlgGZuOAQWqVASwCfVdWM uLZQq1mkf8hsGXOpZtKQH5w= =AxnN -----END PGP SIGNATURE-----