From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wendy Cheng Date: Thu, 24 Jan 2008 16:49:53 -0500 Subject: [Cluster-devel] Re: [PATCH 1/2] NLM failover unlock commands In-Reply-To: <20080124214029.GK26164@fieldses.org> References: <478F78E8.40601@redhat.com> <20080117163105.GG16581@fieldses.org> <478F82DA.4060709@redhat.com> <20080117164002.GH16581@fieldses.org> <478F9946.9010601@redhat.com> <20080117202342.GA6416@fieldses.org> <20080124160030.GB26164@fieldses.org> <4798EAE1.2000707@redhat.com> <20080124201910.GF26164@fieldses.org> <4798FDE9.4040406@redhat.com> <20080124214029.GK26164@fieldses.org> Message-ID: <47990801.6050703@redhat.com> List-Id: To: cluster-devel.redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit J. Bruce Fields wrote: > On Thu, Jan 24, 2008 at 04:06:49PM -0500, Wendy Cheng wrote: > >> J. Bruce Fields wrote: >> >>> On Thu, Jan 24, 2008 at 02:45:37PM -0500, Wendy Cheng wrote: >>> >>> >>>> J. Bruce Fields wrote: >>>> >>>> >>>>> In practice, it seems that both the unlock_ip and unlock_pathname >>>>> methods that revoke locks are going to be called together. The two >>>>> separate calls therefore seem a little redundant. The reason we *need* >>>>> both is that it's possible that a misconfigured client could grab locks >>>>> for a (server ip, export) combination that it isn't supposed to. >>>>> >>>>> >>>> That is not a correct assumption. The two commands (unlock_ip and >>>> unlock_pathname) are not necessarily called together. It is ok for >>>> local filesystem (ext3) but not for cluster filesystem where the >>>> very same filesystem (or subtree) can be exported from multiple >>>> servers using different subtrees. >>>> >>>> >>> Ouch. Are people really doing that, and why? What happens if the >>> subtrees share files (because of hard links) that are locked from both >>> nodes? >>> >>> >> It is *more* common than you would expect - say server1 exports >> "/mnt/gfs/maildir/namea-j" and server2 exports >> "/mnt/gfs/maildir/namek-z". >> > > I believe it, but how hard would it be for them to just set those up as > separate partitions? > > The answers that I normally hear is that "then why would I bother to use a cluster filesystem ?" .... Wendy