Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752715AbbD0Flr (ORCPT ); Mon, 27 Apr 2015 01:41:47 -0400 Received: from cantor2.suse.de ([195.135.220.15]:53691 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751769AbbD0Flo (ORCPT ); Mon, 27 Apr 2015 01:41:44 -0400 Date: Mon, 27 Apr 2015 15:41:33 +1000 From: NeilBrown To: Christoph Hellwig Cc: David Howells , Chris Mason , Al Viro , Josef Bacik , David Sterba , Dave Chinner , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-btrfs@vger.kernel.org Subject: Re: [PATCH 3/3] btrfs: set FS_SUPPORTS_SEEK_HOLE flag. Message-ID: <20150427154133.65f58366@notabene.brown> In-Reply-To: <20150420094855.GA21116@infradead.org> References: <20150420193347.29378d69@notabene.brown> <20150420052752.26554.13596.stgit@notabene.brown> <20150420052558.26554.97143.stgit@notabene.brown> <30419.1429519662@warthog.procyon.org.uk> <31824.1429523209@warthog.procyon.org.uk> <20150420094855.GA21116@infradead.org> X-Mailer: Claws Mail 3.10.1-162-g4d0ed6 (GTK+ 2.24.25; x86_64-suse-linux-gnu) MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; boundary="Sig_/sn6fG6xQ5woy/dSUdoBnjGM"; protocol="application/pgp-signature" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2381 Lines: 66 --Sig_/sn6fG6xQ5woy/dSUdoBnjGM Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Mon, 20 Apr 2015 02:48:55 -0700 Christoph Hellwig wrote: > On Mon, Apr 20, 2015 at 10:46:49AM +0100, David Howells wrote: > > NeilBrown wrote: > >=20 > > > Missing patch 2 of the 3-patch series? > >=20 > > Yes. :-) > >=20 > > Do ext4 and xfs support this, do you know? >=20 > Yes. As do f2fs, ocfs2, gfs2, ceph and NFSv4.2 Are you sure about NFSv4.2? I see that it *can* report holes, but is there any guarantee that if you create a new file and write only the 5th block, then READ_PLUS will reliably report that the first 4 block are holes?? Because if it doesn't guarantee that, then NFSv4.2 doesn't fit the with the others where SEEK_HOLE reliable reports holes. On the other hand if NFSv4.2 *does* guarantee that then the current READ_PL= US server patches are broken because they just use vfs_llseek and assume that trust what it says. It would be really nice if SEEK_{DATA,HOLE} either reported holes reliably = or returned ENXIO, but I guess there was a goo reason not to do that. Thanks, NeilBrown --Sig_/sn6fG6xQ5woy/dSUdoBnjGM Content-Type: application/pgp-signature Content-Description: OpenPGP digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIVAwUBVT3MDTnsnt1WYoG5AQLgIhAAhU7L2vJz6/vekVjSX9d1R59Awzpxpfqd n8MpqPNHVkkg8y/aCMA6QkOmAhFsvFrXOm88Gkh/3NYhcTa7hYodrgSxKPnD6wuR q09r6YB+zYEEQZdTCaiLioOXmCyldn3/HR+BDEnCDmdUqRgf6PdM2dd3pcaYhYH9 dgVaeKgidpqyJOO8RlyzqAGBu6NGbzktIW7bPYbObUYoUiMN6jEeDo8BJ42y8aCC PwtH3K+W5lY2/Wng4Xm5+NZ/GGFifhkdnKghjqR6cVHMQlKsNGci+VqwIGK9CapV YoQ0k4aB4WBDXJe+6EPIG+HG8nugmtLSZG+09/iJj9UiPl2IeCRKiaFVllgJDiFX GmwRWq4Qo1jlmE8RlMsso5hELwz/4xcmDuQRSuTF8PeXchwEXg+I8GXRy3EQAImK NIu6inzAEWHSJeqEpjjCgYpRN1P9xpKUls2kr17Edno+0aVPtc65oooFnGzcxWYu MnIhUzvb/bzhaeXyRdvgNkwqfiXz0u5yx2KlN/w/LAxbxYPj35vMOl8waDZzA/eh 0cC1MdjYA06CCA9Hjl+lxGRal7AvZmF87EoYJqsfFtD0Nygu2iRUkzAlsdoO0CUR 4oQpn4QLwCXsknB3sXgL+LZZWiVWljhgo8gRnI+MhQvfYQEiVBv9hNzITcwP5a2s X5/rzDm+oHc= =Ao0v -----END PGP SIGNATURE----- --Sig_/sn6fG6xQ5woy/dSUdoBnjGM-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/