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[2001:8b0:ffda:0:2059:8730:b2:c370]) by smtp.gmail.com with ESMTPSA id g14sm3636121edr.47.2021.08.20.06.41.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 20 Aug 2021 06:41:32 -0700 (PDT) Message-ID: <2508f12f0d2a5eedaad0c6b77657f53222b33e3c.camel@redhat.com> Subject: Re: [Cluster-devel] [PATCH v6 10/19] gfs2: Introduce flag for glock holder auto-demotion From: Steven Whitehouse To: Bob Peterson , Andreas Gruenbacher , Linus Torvalds , Alexander Viro , Christoph Hellwig , "Darrick J. Wong" Cc: Jan Kara , linux-kernel@vger.kernel.org, Matthew Wilcox , cluster-devel@redhat.com, linux-fsdevel@vger.kernel.org, ocfs2-devel@oss.oracle.com Date: Fri, 20 Aug 2021 14:41:32 +0100 In-Reply-To: References: <20210819194102.1491495-1-agruenba@redhat.com> <20210819194102.1491495-11-agruenba@redhat.com> <5e8a20a8d45043e88013c6004636eae5dadc9be3.camel@redhat.com> Organization: Red Hat UK Ltd Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.34.4 (3.34.4-1.fc31) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Fri, 2021-08-20 at 08:11 -0500, Bob Peterson wrote: > On 8/20/21 4:35 AM, Steven Whitehouse wrote: > > Hi, > > > > On Thu, 2021-08-19 at 21:40 +0200, Andreas Gruenbacher wrote: > > > From: Bob Peterson > > > > > > This patch introduces a new HIF_MAY_DEMOTE flag and > > > infrastructure > > > that > > > will allow glocks to be demoted automatically on locking > > > conflicts. > > > When a locking request comes in that isn't compatible with the > > > locking > > > state of a holder and that holder has the HIF_MAY_DEMOTE flag > > > set, > > > the > > > holder will be demoted automatically before the incoming locking > > > request > > > is granted. > > > > > I'm not sure I understand what is going on here. When there are > > locking > > conflicts we generate call backs and those result in glock > > demotion. > > There is no need for a flag to indicate that I think, since it is > > the > > default behaviour anyway. Or perhaps the explanation is just a bit > > confusing... > > I agree that the whole concept and explanation are confusing. > Andreas > and I went through several heated arguments about the symantics, > comments, patch descriptions, etc. We played around with many > different > flag name ideas, etc. We did not agree on the best way to describe > the > whole concept. He didn't like my explanation and I didn't like his. > So > yes, it is confusing. > That seems to be a good reason to take a step back and look at this a bit closer. If we are finding this confusing, then someone else looking at it at a future date, who may not be steeped in GFS2 knowledge is likely to find it almost impossible. So at least the description needs some work here I think, to make it much clearer what the overall aim is. It would be good to start with a statement of the problem that it is trying to solve which Andreas has hinted at in his reply just now, Steve.