From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id ABD64C54EE9 for ; Tue, 13 Sep 2022 03:31:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229901AbiIMDbZ (ORCPT ); Mon, 12 Sep 2022 23:31:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49842 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230124AbiIMDbN (ORCPT ); Mon, 12 Sep 2022 23:31:13 -0400 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4509D2FFF5; Mon, 12 Sep 2022 20:31:12 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id B133920F49; Tue, 13 Sep 2022 03:31:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1663039870; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Ndgrk0VyINRbdMDLbO7l+2EY0nnzKQILkdX+lROM4VA=; b=D5hQtSVB84872NWPUpgtY00czjq4HsvsBIr9rk8RSxBRplc2NpkS+Hu6+gZUqMDyzVnKik LwMboydU+7qPo2tpYbBb9O8GMLzcyPJnC7dWI02jwBBYc99W/PAYQMWWBYZSx0cnuH9jqi O2/Ebe7v1cJsj1xELWoQ8i411CizawE= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1663039870; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Ndgrk0VyINRbdMDLbO7l+2EY0nnzKQILkdX+lROM4VA=; b=N0gs0x3S8B8VEKQKEbSS/O8mzZ4fMxgFLeyBC06RZkXhl9gC6dsEmRE0DjDXS/MiQS8tHs OsFNtGuvgyAoUdDA== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 8358A13A86; Tue, 13 Sep 2022 03:31:02 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id 8tDhDXb5H2OFNQAAMHmgww (envelope-from ); Tue, 13 Sep 2022 03:31:02 +0000 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit MIME-Version: 1.0 From: "NeilBrown" To: "Dave Chinner" Cc: "Jeff Layton" , "J. Bruce Fields" , "Theodore Ts'o" , "Jan Kara" , adilger.kernel@dilger.ca, djwong@kernel.org, trondmy@hammerspace.com, viro@zeniv.linux.org.uk, zohar@linux.ibm.com, xiubli@redhat.com, chuck.lever@oracle.com, lczerner@redhat.com, brauner@kernel.org, fweimer@redhat.com, linux-man@vger.kernel.org, linux-api@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, ceph-devel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-nfs@vger.kernel.org, linux-xfs@vger.kernel.org Subject: Re: [man-pages RFC PATCH v4] statx, inode: document the new STATX_INO_VERSION field In-reply-to: <20220913024109.GF3600936@dread.disaster.area> References: <20220908155605.GD8951@fieldses.org>, <9e06c506fd6b3e3118da0ec24276e85ea3ee45a1.camel@kernel.org>, <20220908182252.GA18939@fieldses.org>, <44efe219dbf511492b21a653905448d43d0f3363.camel@kernel.org>, <20220909154506.GB5674@fieldses.org>, <125df688dbebaf06478b0911e76e228e910b04b3.camel@kernel.org>, <20220910145600.GA347@fieldses.org>, <9eaed9a47d1aef11fee95f0079e302bc776bc7ff.camel@kernel.org>, <20220913004146.GD3600936@dread.disaster.area>, <166303374350.30452.17386582960615006566@noble.neil.brown.name>, <20220913024109.GF3600936@dread.disaster.area> Date: Tue, 13 Sep 2022 13:30:58 +1000 Message-id: <166303985824.30452.7333958999671590160@noble.neil.brown.name> Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org On Tue, 13 Sep 2022, Dave Chinner wrote: > > Indeed, we know there are many systems out there that mount a > filesystem, preallocate and map the blocks that are allocated to a > large file, unmount the filesysetm, mmap the ranges of the block > device and pass them to RDMA hardware, then have sensor arrays rdma > data directly into the block device. Then when the measurement > application is done they walk the ondisk metadata to remove the > unwritten flags on the extents, mount the filesystem again and > export the file data to a HPC cluster for post-processing..... And this tool doesn't update the i_version? Sounds like a bug. > > So how does the filesystem know whether data the storage contains > for it's files has been modified while it is unmounted and so needs > to change the salt? How does it know that no data is modified while it *is* mounted? Some assumptions have to be made. > > The short answer is that it can't, and so we cannot make assumptions > that a unmount/mount cycle has not changed the filesystem in any > way.... If a mount-count is the best that XFS can do, then that is certainly what it should use. Thanks, NeilBrown