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 B3B7CC4332F for ; Thu, 9 Nov 2023 16:41:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344606AbjKIQlm (ORCPT ); Thu, 9 Nov 2023 11:41:42 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37498 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344754AbjKIQkr (ORCPT ); Thu, 9 Nov 2023 11:40:47 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D2F184220 for ; Thu, 9 Nov 2023 08:38:56 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 75D44C433C9; Thu, 9 Nov 2023 16:38:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1699547936; bh=bkdMTVjQse1cJXkwlSeNrJqtIRuV61o2Whlzq2oeE+Y=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=s3+xz+5ul0Jj/Lh+TRvXzZR8fl7Joi2xybHVBz4kCxHVi+cadXR+dkOb9l0F8oHPg 1CWv/fBoCE8eEcggDkvQkvkQ/BzLIdU+WpSu58xtqMcqsOPMwwALpuqvioF2XW9+m5 xwXyEqSKGC6JRQQx1ha+OqR0KH6qXJ2vMbkWwquYCfdHbS3F7PAvbg8dekjKVQ5qzQ xtsLzcSZvEBw3k7+uYsjhSueqDHAcryd+pu9rDLJY6OiUglInF0uiXRu1oyFFeCTnT 84t1/97BMtaGROE8TDNHdE3p/3LYjjaRUVYaOnl7IYlx2TZOqF+6ppVHAulv594EG2 z6QR36lGul8dw== Date: Thu, 9 Nov 2023 08:38:56 -0800 From: "Darrick J. Wong" To: Christoph Hellwig Cc: Linus Torvalds , Chandan Babu R , Jeff Layton , Christian Brauner , catherine.hoang@oracle.com, cheng.lin130@zte.com.cn, dchinner@redhat.com, linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org, osandov@fb.com Subject: Re: [GIT PULL] xfs: new code for 6.7 Message-ID: <20231109163856.GG1205143@frogsfrogsfrogs> References: <87fs1g1rac.fsf@debian-BULLSEYE-live-builder-AMD64> <20231108225200.GY1205143@frogsfrogsfrogs> <20231109045150.GB28458@lst.de> <20231109073945.GE1205143@frogsfrogsfrogs> <20231109144614.GA31340@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231109144614.GA31340@lst.de> Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Thu, Nov 09, 2023 at 03:46:14PM +0100, Christoph Hellwig wrote: > On Wed, Nov 08, 2023 at 11:39:45PM -0800, Darrick J. Wong wrote: > > Dave and I started looking at this too, and came up with: For rtgroups > > filesystems, what if rtpick simply rotored the rtgroups? And what if we > > didn't bother persisting the rotor value, which would make this casting > > nightmare go away in the long run. It's not like we persist the agi > > rotors. > > Yep. We should still fix the cast and replace it with a proper union > or other means for pre-RTG file systems given that they will be around > for while. Linus' fixup stuffs the seq value in tv_sec. That's not great since the inode writeout code then truncates the upper 32 bits, but that's what the kernel has been doing for 5+ years now. Dave suggested that we might restore the pre-4.6 behavior by explicitly encoding what we used to do: inode->i_atime.tv_sec = seq & 0xFFFFFFFF; inode->i_atime.tv_nsec = seq >> 32; (There's a helper in 6.7 for this, apparently.) But then I pointed out that the entire rtpick sequence counter thing merely provides a *starting point* for rtbitmap searches. So it's not like garbled values result in metadata inconsistency. IOWs, it's apparently benign. IOWs, how much does anyone care about improving on Linus' fixup? --D