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From:   Chuck Lever III <chuck.lever@oracle.com>
To:     Jeff Layton <jlayton@kernel.org>
CC:     Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
        Petr Vorel <pvorel@suse.cz>
Subject: Re: [PATCH] nfsd: fix net-namespace logic in __nfsd_file_cache_purge
Thread-Topic: [PATCH] nfsd: fix net-namespace logic in __nfsd_file_cache_purge
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Date:   Mon, 31 Oct 2022 15:41:15 +0000
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> On Oct 31, 2022, at 11:35 AM, Jeff Layton <jlayton@kernel.org> wrote:
>=20
> If the namespace doesn't match the one in "net", then we'll continue,
> but that doesn't cause another rhashtable_walk_next call, so it will
> loop infinitely.
>=20
> Fixes: ce502f81ba88 ("NFSD: Convert the filecache to use rhashtable")
> Reported-by: Petr Vorel <pvorel@suse.cz>
> Signed-off-by: Jeff Layton <jlayton@kernel.org>
> ---
> fs/nfsd/filecache.c | 20 +++++++++-----------
> 1 file changed, 9 insertions(+), 11 deletions(-)
>=20
> This should probably go to stable too.

I tried to apply this to for-rc, but the WARN_ON_ONCE logic
has already been removed there. Can you rebase and resend?


> diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
> index eeed4ae5b4ad..f9ea89057ae8 100644
> --- a/fs/nfsd/filecache.c
> +++ b/fs/nfsd/filecache.c
> @@ -908,19 +908,17 @@ __nfsd_file_cache_purge(struct net *net)
>=20
> 		nf =3D rhashtable_walk_next(&iter);
> 		while (!IS_ERR_OR_NULL(nf)) {
> -			if (net && nf->nf_net !=3D net)
> -				continue;
> -			del =3D nfsd_file_unhash_and_dispose(nf, &dispose);
> -
> -			/*
> -			 * Deadlock detected! Something marked this entry as
> -			 * unhased, but hasn't removed it from the hash list.
> -			 */
> -			WARN_ON_ONCE(!del);
> -
> +			if (!net || nf->nf_net =3D=3D net) {
> +				del =3D nfsd_file_unhash_and_dispose(nf, &dispose);
> +
> +				/*
> +				 * Deadlock detected! Something marked this entry as
> +				 * unhased, but hasn't removed it from the hash list.
> +				 */
> +				WARN_ON_ONCE(!del);
> +			}
> 			nf =3D rhashtable_walk_next(&iter);
> 		}
> -
> 		rhashtable_walk_stop(&iter);
> 	} while (nf =3D=3D ERR_PTR(-EAGAIN));
> 	rhashtable_walk_exit(&iter);
> --=20
> 2.38.1
>=20

--
Chuck Lever