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Subject: Re: [nfs-utils PATCH] Don't allow junction tests to trigger
 automounts
From:   Jeff Layton <jlayton@kernel.org>
To:     steved@redhat.com
Cc:     linux-nfs@vger.kernel.org, Chuck Lever <chuck.lever@oracle.com>,
        JianHong Yin <jiyin@redhat.com>
Date:   Wed, 04 Jan 2023 07:23:58 -0500
In-Reply-To: <20221213160104.198237-1-jlayton@kernel.org>
References: <20221213160104.198237-1-jlayton@kernel.org>
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On Tue, 2022-12-13 at 11:01 -0500, Jeff Layton wrote:
> JianHong reported some strange behavior with automounts on an nfs server
> without an explicit pseudoroot. When clients issued a readdir in the
> pseudoroot, automounted directories that were not yet mounted would show
> up even if they weren't exported, though the clients wouldn't be able to
> do anything with them.
>=20
> The issue was that triggering the automount on a directory would cause
> the mountd upcall to time out, which would cause nfsd to include the
> automounted dentry in the readdir response. Eventually, the automount
> would work and report that it wasn't exported and subsequent attempts to
> access the dentry would (properly) fail.
>=20
> We never want mountd to trigger an automount. The kernel should do that
> if it wants to use it. Change the junction checks to do an O_PATH open
> and use fstatat with AT_NO_AUTOMOUNT.
>=20
> Cc: Chuck Lever <chuck.lever@oracle.com>
> Link: https://bugzilla.redhat.com/show_bug.cgi?id=3D2148353
> Reported-by: JianHong Yin <jiyin@redhat.com>
> Signed-off-by: Jeff Layton <jlayton@kernel.org>
> ---
>  support/junction/junction.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
>=20

Ping? Steve, can you comment on (or merge) this patch?

Thanks,
--=20
Jeff Layton <jlayton@kernel.org>