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 X-Spam-Level: X-Spam-Status: No, score=-16.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 20CFDC433C1 for ; Mon, 22 Mar 2021 16:43:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E94C561931 for ; Mon, 22 Mar 2021 16:43:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229822AbhCVQnT (ORCPT ); Mon, 22 Mar 2021 12:43:19 -0400 Received: from mail.kernel.org ([198.145.29.99]:35152 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230364AbhCVQm4 (ORCPT ); Mon, 22 Mar 2021 12:42:56 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 5C4456198D; Mon, 22 Mar 2021 16:42:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1616431376; bh=eiLBm6C4ky4iMXhrWyw9o6JspRAiQS5Yd9YT0Jh1pEo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=TydDahE+qFG8Cfp61pFWt4VFHy3k3bT8WBivqXoDj6FBRokKuI6ge7MkU1skkQjBC 663oexos5ub9OWqpwgJz9OrvPuHyntBQlO6ufS3ZisYG4uscsPXE9HqDflVWW9T8u9 iJXIAINcmFMFymjH53moRgMAfoP6gUxWaFK4HpgQX5uAXAiwIX0XHVZJaY/6+rLqe7 XQg1K5yurxX3H361ensW7L1Kvv2qqV+dgqIN9JO3m5Z48eDIWeT/G+jS6K+CTR0ZXl a//yZ9HXVqepFEeeg2f7QXfQ/dTB67NVDt6iKvOBT7xdJmUq1mfSNi3rKBUvft2r5u 62C7ON8n74xmg== Date: Mon, 22 Mar 2021 09:42:55 -0700 From: "Darrick J. Wong" To: Gao Xiang Cc: Brian Foster , linux-xfs@vger.kernel.org, Dave Chinner , Christoph Hellwig , Eric Sandeen Subject: Re: [PATCH v8 4/5] xfs: support shrinking unused space in the last AG Message-ID: <20210322164255.GE22100@magnolia> References: <20210305025703.3069469-1-hsiangkao@redhat.com> <20210305025703.3069469-5-hsiangkao@redhat.com> <20210322120722.GC2000812@xiangao.remote.csb> <20210322123652.GB2007006@xiangao.remote.csb> <20210322125028.GC2007006@xiangao.remote.csb> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210322125028.GC2007006@xiangao.remote.csb> Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Mon, Mar 22, 2021 at 08:50:28PM +0800, Gao Xiang wrote: > On Mon, Mar 22, 2021 at 08:43:19AM -0400, Brian Foster wrote: > > On Mon, Mar 22, 2021 at 08:36:52PM +0800, Gao Xiang wrote: > > > On Mon, Mar 22, 2021 at 08:26:41AM -0400, Brian Foster wrote: > > > > On Mon, Mar 22, 2021 at 08:07:22PM +0800, Gao Xiang wrote: > > > > > On Mon, Mar 22, 2021 at 07:30:40AM -0400, Brian Foster wrote: > > > > > > On Fri, Mar 05, 2021 at 10:57:02AM +0800, Gao Xiang wrote: > > > > > > > As the first step of shrinking, this attempts to enable shrinking > > > > > > > unused space in the last allocation group by fixing up freespace > > > > > > > btree, agi, agf and adjusting super block and use a helper > > > > > > > xfs_ag_shrink_space() to fixup the last AG. > > > > > > > > > > > > > > This can be all done in one transaction for now, so I think no > > > > > > > additional protection is needed. > > > > > > > > > > > > > > Reviewed-by: Darrick J. Wong > > > > > > > Signed-off-by: Gao Xiang > > > > > > > --- > > > > > > > fs/xfs/xfs_fsops.c | 88 ++++++++++++++++++++++++++++------------------ > > > > > > > fs/xfs/xfs_trans.c | 1 - > > > > > > > 2 files changed, 53 insertions(+), 36 deletions(-) > > > > > > > > > > > > > > diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c > > > > > > > index fc9e799b2ae3..71cba61a451c 100644 > > > > > > > --- a/fs/xfs/xfs_fsops.c > > > > > > > +++ b/fs/xfs/xfs_fsops.c > > > > ... > > > > > > > @@ -115,10 +120,15 @@ xfs_growfs_data_private( > > > > > > > if (nb_mod && nb_mod < XFS_MIN_AG_BLOCKS) { > > > > > > > nagcount--; > > > > > > > nb = (xfs_rfsblock_t)nagcount * mp->m_sb.sb_agblocks; > > > > > > > - if (nb < mp->m_sb.sb_dblocks) > > > > > > > - return -EINVAL; > > > > > > > } > > > > > > > delta = nb - mp->m_sb.sb_dblocks; > > > > > > > + /* > > > > > > > + * XFS doesn't really support single-AG filesystems, so do not > > > > > > > + * permit callers to remove the filesystem's second and last AG. > > > > > > > + */ > > > > > > > + if (delta < 0 && nagcount < 2) > > > > > > > + return -EINVAL; > > > > > > > + > > > > > > > > > > > > What if the filesystem is already single AG? Unless I'm missing > > > > > > something, we already have a check a bit further down that prevents > > > > > > removal of AGs in the first place. > > > > > > > > > > I think it tends to forbid (return -EINVAL) shrinking the filesystem with > > > > > a single AG only? Am I missing something? > > > > > > > > > > > > > My assumption was this check means one can't shrink a filesystem that is > > > > already agcount == 1. The comment refers to preventing shrink from > > > > causing an agcount == 1 fs. What is the intent? Both of those things. > > > > > > I think it means the latter -- preventing shrink from causing an agcount == 1 > > > fs. since nagcount (new agcount) <= 1? > > > > > > > Right, so that leads to my question... does this check also fail a > > shrink on an fs that is already agcount == 1? If so, why? I know > > technically it's not a supported configuration, but mkfs allows it. > > Ah, I'm not sure if Darrick would like to forbid agcount == 1 shrinking > functionitity completely, see the previous comment: > https://lore.kernel.org/r/20201014160633.GD9832@magnolia/ > > (please ignore the modification at that time, since it was buggy...) Given the confusion I propose a new comment: /* * Reject filesystems with a single AG because they are not * supported, and reject a shrink operation that would cause a * filesystem to become unsupported. */ if (delta < 0 && nagcount < 2) return -EINVAL; --D > > Thanks, > Gao Xiang > > > > > Brian > > > > > Actually, I'm not good at English, if comments need to be improved, please > > > kindly point out. Thank you very much! > > > > > > Thanks, > > > Gao Xiang > > > > > > > > > > > Brian > > > > > > > > > Thanks, > > > > > Gao Xiang > > > > > > > > > > > > > > > > > Otherwise looks reasonable.. > > > > > > > > > > > > Brian > > > > > > > > > > > > > oagcount = mp->m_sb.sb_agcount; > > > > > > > > > > > > > > /* allocate the new per-ag structures */ > > > > > > > @@ -126,15 +136,22 @@ xfs_growfs_data_private( > > > > > > > error = xfs_initialize_perag(mp, nagcount, &nagimax); > > > > > > > if (error) > > > > > > > return error; > > > > > > > + } else if (nagcount < oagcount) { > > > > > > > + /* TODO: shrinking the entire AGs hasn't yet completed */ > > > > > > > + return -EINVAL; > > > > > > > } > > > > > > > > > > > > > > error = xfs_trans_alloc(mp, &M_RES(mp)->tr_growdata, > > > > > > > - XFS_GROWFS_SPACE_RES(mp), 0, XFS_TRANS_RESERVE, &tp); > > > > > > > + (delta > 0 ? XFS_GROWFS_SPACE_RES(mp) : -delta), 0, > > > > > > > + XFS_TRANS_RESERVE, &tp); > > > > > > > if (error) > > > > > > > return error; > > > > > > > > > > > > > > - error = xfs_resizefs_init_new_ags(tp, &id, oagcount, nagcount, > > > > > > > - delta, &lastag_resetagres); > > > > > > > + if (delta > 0) > > > > > > > + error = xfs_resizefs_init_new_ags(tp, &id, oagcount, nagcount, > > > > > > > + delta, &lastag_resetagres); > > > > > > > + else > > > > > > > + error = xfs_ag_shrink_space(mp, &tp, nagcount - 1, -delta); > > > > > > > if (error) > > > > > > > goto out_trans_cancel; > > > > > > > > > > > > > > @@ -145,7 +162,7 @@ xfs_growfs_data_private( > > > > > > > */ > > > > > > > if (nagcount > oagcount) > > > > > > > xfs_trans_mod_sb(tp, XFS_TRANS_SB_AGCOUNT, nagcount - oagcount); > > > > > > > - if (delta > 0) > > > > > > > + if (delta) > > > > > > > xfs_trans_mod_sb(tp, XFS_TRANS_SB_DBLOCKS, delta); > > > > > > > if (id.nfree) > > > > > > > xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, id.nfree); > > > > > > > @@ -169,28 +186,29 @@ xfs_growfs_data_private( > > > > > > > xfs_set_low_space_thresholds(mp); > > > > > > > mp->m_alloc_set_aside = xfs_alloc_set_aside(mp); > > > > > > > > > > > > > > - /* > > > > > > > - * If we expanded the last AG, free the per-AG reservation > > > > > > > - * so we can reinitialize it with the new size. > > > > > > > - */ > > > > > > > - if (lastag_resetagres) { > > > > > > > - struct xfs_perag *pag; > > > > > > > - > > > > > > > - pag = xfs_perag_get(mp, id.agno); > > > > > > > - error = xfs_ag_resv_free(pag); > > > > > > > - xfs_perag_put(pag); > > > > > > > - if (error) > > > > > > > - return error; > > > > > > > + if (delta > 0) { > > > > > > > + /* > > > > > > > + * If we expanded the last AG, free the per-AG reservation > > > > > > > + * so we can reinitialize it with the new size. > > > > > > > + */ > > > > > > > + if (lastag_resetagres) { > > > > > > > + struct xfs_perag *pag; > > > > > > > + > > > > > > > + pag = xfs_perag_get(mp, id.agno); > > > > > > > + error = xfs_ag_resv_free(pag); > > > > > > > + xfs_perag_put(pag); > > > > > > > + if (error) > > > > > > > + return error; > > > > > > > + } > > > > > > > + /* > > > > > > > + * Reserve AG metadata blocks. ENOSPC here does not mean there > > > > > > > + * was a growfs failure, just that there still isn't space for > > > > > > > + * new user data after the grow has been run. > > > > > > > + */ > > > > > > > + error = xfs_fs_reserve_ag_blocks(mp); > > > > > > > + if (error == -ENOSPC) > > > > > > > + error = 0; > > > > > > > } > > > > > > > - > > > > > > > - /* > > > > > > > - * Reserve AG metadata blocks. ENOSPC here does not mean there was a > > > > > > > - * growfs failure, just that there still isn't space for new user data > > > > > > > - * after the grow has been run. > > > > > > > - */ > > > > > > > - error = xfs_fs_reserve_ag_blocks(mp); > > > > > > > - if (error == -ENOSPC) > > > > > > > - error = 0; > > > > > > > return error; > > > > > > > > > > > > > > out_trans_cancel: > > > > > > > diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c > > > > > > > index 44f72c09c203..d047f5f26cc0 100644 > > > > > > > --- a/fs/xfs/xfs_trans.c > > > > > > > +++ b/fs/xfs/xfs_trans.c > > > > > > > @@ -434,7 +434,6 @@ xfs_trans_mod_sb( > > > > > > > tp->t_res_frextents_delta += delta; > > > > > > > break; > > > > > > > case XFS_TRANS_SB_DBLOCKS: > > > > > > > - ASSERT(delta > 0); > > > > > > > tp->t_dblocks_delta += delta; > > > > > > > break; > > > > > > > case XFS_TRANS_SB_AGCOUNT: > > > > > > > -- > > > > > > > 2.27.0 > > > > > > > > > > > > > > > > > > > > > > > > > > > >