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Date:   Mon, 20 Jul 2020 19:17:06 +0100
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     Christoph Hellwig <hch@lst.de>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
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Subject: Re: [PATCH 06/24] fs: add a kern_chdir helper
Message-ID: <20200720181706.GR2786714@ZenIV.linux.org.uk>
References: <20200720155902.181712-1-hch@lst.de>
 <20200720155902.181712-7-hch@lst.de>
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On Mon, Jul 20, 2020 at 05:58:44PM +0200, Christoph Hellwig wrote:
> Add a simple helper for a chdir with a kernelspace name and use it in the
> early init code instead of relying on the implicit set_fs(KERNEL_DS)
> there.  Remove the now unused ksys_chdir.

FWIW, my problem with that is that you are making it first-class primitive.
And I don't see any valid use for it - existing one is really "we have
a userland process that would be making syscalls if we only could have it
done right; the only reason we can't is that the infrastructure to build
the binary would be hell to maintain in the tree".  It's *NOT* "kernel
code that has a valid reason to get the syscall functionality".