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Wong" Cc: linux-xfs@vger.kernel.org, Brian Foster , Eric Sandeen Subject: Re: [PATCH v3 4/4] xfs: support shrinking unused space in the last AG Message-ID: <20210109004741.GA660098@xiangao.remote.csb> References: <20210108190919.623672-1-hsiangkao@redhat.com> <20210108190919.623672-5-hsiangkao@redhat.com> <20210108211942.GQ38809@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20210108211942.GQ38809@magnolia> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org Hi Darrick, On Fri, Jan 08, 2021 at 01:19:42PM -0800, Darrick J. Wong wrote: > On Sat, Jan 09, 2021 at 03:09:19AM +0800, Gao Xiang wrote: ... > > delta = nb; /* use delta as a temporary here */ > > Yikes, can this become a separate variable please? Ok. > > > nb_mod = do_div(delta, mp->m_sb.sb_agblocks); > > @@ -99,10 +102,18 @@ 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) > > + if (nagcount < 2) > > return -EINVAL; > > } > > - delta = nb - mp->m_sb.sb_dblocks; > > + > > + if (nb > mp->m_sb.sb_dblocks) { > > + delta = nb - mp->m_sb.sb_dblocks; > > + extend = true; > > + } else { > > + delta = mp->m_sb.sb_dblocks - nb; > > + extend = false; > > /me wonders why delta isn't simply int64_t, and then you can do things > like: > > if (delta > 0) > growfs > else if (delta < 0) > shrinkfs > > ? Yeah, delta changed into a signed variable in mycurrent experimental shrinking entire AG hack as well. Will update this here in advance. Thanks, Gao Xiang