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Subject: Re: [PATCH] NFSD: Fix 5 seconds delay when doing inter server copy
From:   Chuck Lever <chuck.lever@oracle.com>
In-Reply-To: <20201130212449.3470-1-dai.ngo@oracle.com>
Date:   Mon, 30 Nov 2020 16:38:06 -0500
Cc:     Bruce Fields <bfields@fieldses.org>,
        Linux NFS Mailing List <linux-nfs@vger.kernel.org>
Content-Transfer-Encoding: quoted-printable
Message-Id: <7AD569D2-BBEB-4F2D-9673-59E3CA4E89E1@oracle.com>
References: <20201130212449.3470-1-dai.ngo@oracle.com>
To:     Dai Ngo <dai.ngo@oracle.com>
Precedence: bulk


> On Nov 30, 2020, at 4:24 PM, Dai Ngo <dai.ngo@oracle.com> wrote:
>=20
> Since commit b4868b44c5628 ("NFSv4: Wait for stateid updates after
> CLOSE/OPEN_DOWNGRADE"), every inter server copy operation suffers 5
> seconds delay regardless of the size of the copy. The delay is from
> nfs_set_open_stateid_locked when the check by =
nfs_stateid_is_sequential
> fails because the seqid in both nfs4_state and nfs4_stateid are 0.
>=20
> Fix by modifying nfs4_init_cp_state to return the stateid with seqid 1
> instead of 0. This is also to conform with section 4.8 of RFC 7862.
>=20
> Here is the relevant paragraph from section 4.8 of RFC 7862:
>=20
>   A copy offload stateid's seqid MUST NOT be zero.  In the context of =
a
>   copy offload operation, it is inappropriate to indicate "the most
>   recent copy offload operation" using a stateid with a seqid of zero
>   (see Section 8.2.2 of [RFC5661]).  It is inappropriate because the
>   stateid refers to internal state in the server and there may be
>   several asynchronous COPY operations being performed in parallel on
>   the same file by the server.  Therefore, a copy offload stateid with
>   a seqid of zero MUST be considered invalid.
>=20
> Fixes: ce0887ac96d3 ("NFSD add nfs4 inter ssc to nfsd4_copy")
> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>

Applied for the next merge window. See the cel-next topic branch in
this repo:

git://git.linux-nfs.org/projects/cel/cel-2.6.git

See also:

=
http://git.linux-nfs.org/?p=3Dcel/cel-2.6.git;a=3Dshortlog;h=3Drefs/heads/=
cel-next


> ---
> fs/nfsd/nfs4state.c | 1 +
> 1 file changed, 1 insertion(+)
>=20
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index d7f27ed6b794..47006eec724e 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -769,6 +769,7 @@ static int nfs4_init_cp_state(struct nfsd_net *nn, =
copy_stateid_t *stid,
> 	spin_lock(&nn->s2s_cp_lock);
> 	new_id =3D idr_alloc_cyclic(&nn->s2s_cp_stateids, stid, 0, 0, =
GFP_NOWAIT);
> 	stid->stid.si_opaque.so_id =3D new_id;
> +	stid->stid.si_generation =3D 1;
> 	spin_unlock(&nn->s2s_cp_lock);
> 	idr_preload_end();
> 	if (new_id < 0)
> --=20
> 2.9.5
>=20

--
Chuck Lever