From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Braam Date: Wed, 04 Jun 2008 10:17:27 +0900 Subject: [Lustre-devel] Re-direction inodes In-Reply-To: <20080602170937.GI2961@webber.adilger.int> Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: lustre-devel@lists.lustre.org The last sentence in your message is correct. But it seems that Nikita and I have managed to design it "out of the way" - I'll write it up and share it with you. Peter On 6/3/08 2:09 AM, "Andreas Dilger" wrote: > On Jun 02, 2008 08:59 +0900, Peter J. Braam wrote: >> I have a need in doing an architecture for a customer of a Lustre client >> feature to have different data/page caches associated with an inode, >> depending on the user that accesses it. So when a file is read, user A >> will read different data from user B (assume the same for writes, but I >> think this is a read-only feature). > > Initially when I read this, I thought you were only trying to keep the > client-side cache separate, which could be done by adding the UID into > the inode lookup function for ll_test_inode() and treating these files > separately in the client-side cache. That would be useful to avoid e.g. > user A reading "securefile" into memory, and user B being able to access > it from cache due to client-local access permissions allowing it. > >> I remember that in the Coda file system we could easily re-direct I/O to >> another inode using almost standard features in the VFS/page caches. Is >> this still the case? Would this work for the purpose I describe above? > > On later reading, it seems you want to have completely independent > file contents for each user, but they share the same pathname. In some > filesystems it is possible to encode part of the pathname somewhat like: > > /home///$UID///file > > but I think you are proposing a completely transparent mapping of content: > > alice> cat /etc/passwd > alice:x:1000:1000:Alice:/home/alice:/bin/bash > > bob> cat /etc/passwd > bob:x:1001:1001:Bob:/home/bob:/bin/bash > > correct? > > Cheers, Andreas > -- > Andreas Dilger > Sr. Staff Engineer, Lustre Group > Sun Microsystems of Canada, Inc. > > _______________________________________________ > Lustre-devel mailing list > Lustre-devel at lists.lustre.org > http://lists.lustre.org/mailman/listinfo/lustre-devel