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Date:   Wed, 13 Jan 2021 15:30:13 +0000
From:   "hch@infradead.org" <hch@infradead.org>
To:     Trond Myklebust <trondmy@hammerspace.com>
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        "pgoetz@math.utexas.edu" <pgoetz@math.utexas.edu>,
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        "bfields@fieldses.org" <bfields@fieldses.org>,
        "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>
Subject: Re: nfsd vurlerability submit
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On Wed, Jan 13, 2021 at 03:16:52PM +0000, Trond Myklebust wrote:
> How would that work then? Would you just look at the project ID of the
> directory identified by the filehandle as the export point, and then
> match to the project ID on the target inode? That sounds like it
> doesn't even need to encode anything special in the filehandle.

True, we would not even have to encode them.

> How do you set a project ID in XFS?

With the XFS_IOC_SETXFLAGS ioctl.

On the command line side people usually do it using the xfs_quota
tool as part of setting up the tree quotas, but it can also be done
separately using the chproj subcommand of xfs_io.