From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5A8C030507B; Tue, 2 Sep 2025 13:40:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756820441; cv=none; b=XUXRuFfKSSgspawafLp06BmZ2xXDAu1VIqRJ97oWZkBx7UQyKXqQ+vvaO7qgh6SNMhRHkFEvoDZ03eDusU8aDY74+N7GpXjBDrQzwEEx97gRiKchd1Yd83H9q9I6GMkvZcjtg594lj/Tq3EH+1Uau0gru853VfWjTgC3VNg1PLU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756820441; c=relaxed/simple; bh=e6Zn8P4/mGD/2aR+Wv1kt0PRjwWwH22Kv/fMhX//tIo=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=W9jWFbXyTqkkjtGIQ9jdrqAIUA3RKcucbP33cKvv8GEuzxiAQjATZpT8TA9L75og4F/9Z5Tm2WvC2QU4cyHnnuh0Mhko0uJmYVqrDZQH8FNVB8HNJFCW2TWql4ph99c70UnyDVVVZXs3P/pnbtAmJo5laBDuFZQMtALDOQESt18= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=f3ibJ0zj; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="f3ibJ0zj" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 12315C4CEED; Tue, 2 Sep 2025 13:40:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1756820441; bh=e6Zn8P4/mGD/2aR+Wv1kt0PRjwWwH22Kv/fMhX//tIo=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=f3ibJ0zjaZFKBZMbfwcnbIoRUuCZyQqVlIbKb8YdKNN57ooMQCSfVskU3e6mhUHTx Wfi/GkzWEvtGS23x/bJ9Y6BN16PaIN04DANdoif+EzFFuXdBii/l1Qdd0zkWd16ACN jLUEU2FmBixI01v8XOFV8VNt6+XdeiRnEq1y/QK/6AnMFoaCIfKsRUVxf3jgNM+xNl vC7aAOLFDPy48v9a/b/nLhyuGXzWfMZRp2KJD8s9q7VMHNZZSmIcRCgOs1PzoW5AUU S9ziBv874KvVn3Yxs9YiZd0SR7x2PICmPbuomn8vObPo0RlzJ2K8E1tpLSuCfHtXaj DM06gr4m8EpuQ== Message-ID: Subject: Re: [PATCH] nfsd: remove long-standing revoked delegations by force From: Jeff Layton To: Li Lingfeng , chuck.lever@oracle.com, neil@brown.name, okorniev@redhat.com, Dai.Ngo@oracle.com, tom@talpey.com, linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org Cc: yukuai1@huaweicloud.com, houtao1@huawei.com, yi.zhang@huawei.com, yangerkun@huawei.com, lilingfeng@huaweicloud.com, zhangjian496@huawei.com Date: Tue, 02 Sep 2025 09:40:38 -0400 In-Reply-To: <1ece2978-239c-4939-bb16-0c7c64614c66@huawei.com> References: <20250902022237.1488709-1-lilingfeng3@huawei.com> <1ece2978-239c-4939-bb16-0c7c64614c66@huawei.com> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV T2h6v8i8YqsATFPwO4nuiTmL6I40ZofxVd+9wdRI4Db8yUNA4ZSP2nqLcLtFjClYRBoJvRWvsv4lm 0OX6MYPtv76hka8lW4mnRmZqqx3UtfHX/hF/zH24Gj7A6sYKYLCU3YrI2Ogiu7/ksKcl7goQjpvtV YrOOI5VGLHge0awt7bhMCTM9KAfPc+xL/ZxAMVWd3NCk5SamL2cE99UWgtvNOIYU8m6EjTLhsj8sn VluJH0/RcxEeFbnSaswVChNSGa7mXJrTR22lRL6ZPjdMgS2Km90haWPRc8Wolcz07Y2se0xpGVLEQ cDEsvv5IMmeMe1/qLZ6NaVkNuL3WOXvxaVT9USW1+/SGipO2IpKJjeDZfehlB/kpfF24+RrK+seQf CBYyUE8QJpvTZyfUHNYldXlrjO6n5MdOempLqWpfOmcGkwnyNRBR46g/jf8KnPRwXs509yAqDB6sE LZH+yWr9LQZEwARAQABtCVKZWZmIExheXRvbiA8amxheXRvbkBwb29jaGllcmVkcy5uZXQ+iQI7BB MBAgAlAhsDBgsJCAcDAgYVCAIJCgsEFgIDAQIeAQIXgAUCTpXWPAIZAQAKCRAADmhBGVaCFc65D/4 gBLNMHopQYgG/9RIM3kgFCCQV0pLv0hcg1cjr+bPI5f1PzJoOVi9s0wBDHwp8+vtHgYhM54yt43uI 7Htij0RHFL5eFqoVT4TSfAg2qlvNemJEOY0e4daljjmZM7UtmpGs9NN0r9r50W82eb5Kw5bc/r0km R/arUS2st+ecRsCnwAOj6HiURwIgfDMHGPtSkoPpu3DDp/cjcYUg3HaOJuTjtGHFH963B+f+hyQ2B rQZBBE76ErgTDJ2Db9Ey0kw7VEZ4I2nnVUY9B5dE2pJFVO5HJBMp30fUGKvwaKqYCU2iAKxdmJXRI ONb7dSde8LqZahuunPDMZyMA5+mkQl7kpIpR6kVDIiqmxzRuPeiMP7O2FCUlS2DnJnRVrHmCljLkZ Wf7ZUA22wJpepBligemtSRSbqCyZ3B48zJ8g5B8xLEntPo/NknSJaYRvfEQqGxgk5kkNWMIMDkfQO lDSXZvoxqU9wFH/9jTv1/6p8dHeGM0BsbBLMqQaqnWiVt5mG92E1zkOW69LnoozE6Le+12DsNW7Rj iR5K+27MObjXEYIW7FIvNN/TQ6U1EOsdxwB8o//Yfc3p2QqPr5uS93SDDan5ehH59BnHpguTc27Xi QQZ9EGiieCUx6Zh2ze3X2UW9YNzE15uKwkkuEIj60NvQRmEDfweYfOfPVOueC+iFifbQgSmVmZiBM YXl0b24gPGpsYXl0b25AcmVkaGF0LmNvbT6JAjgEEwECACIFAk6V0q0CGwMGCwkIBwMCBhUIAgkKC wQWAgMBAh4BAheAAAoJEAAOaEEZVoIViKUQALpvsacTMWWOd7SlPFzIYy2/fjvKlfB/Xs4YdNcf9q LqF+lk2RBUHdR/dGwZpvw/OLmnZ8TryDo2zXVJNWEEUFNc7wQpl3i78r6UU/GUY/RQmOgPhs3epQC 3PMJj4xFx+VuVcf/MXgDDdBUHaCTT793hyBeDbQuciARDJAW24Q1RCmjcwWIV/pgrlFa4lAXsmhoa c8UPc82Ijrs6ivlTweFf16VBc4nSLX5FB3ls7S5noRhm5/Zsd4PGPgIHgCZcPgkAnU1S/A/rSqf3F LpU+CbVBDvlVAnOq9gfNF+QiTlOHdZVIe4gEYAU3CUjbleywQqV02BKxPVM0C5/oVjMVx3bri75n1 TkBYGmqAXy9usCkHIsG5CBHmphv9MHmqMZQVsxvCzfnI5IO1+7MoloeeW/lxuyd0pU88dZsV/riHw 87i2GJUJtVlMl5IGBNFpqoNUoqmvRfEMeXhy/kUX4Xc03I1coZIgmwLmCSXwx9MaCPFzV/dOOrju2 xjO+2sYyB5BNtxRqUEyXglpujFZqJxxau7E0eXoYgoY9gtFGsspzFkVNntamVXEWVVgzJJr/EWW0y +jNd54MfPRqH+eCGuqlnNLktSAVz1MvVRY1dxUltSlDZT7P2bUoMorIPu8p7ZCg9dyX1+9T6Muc5d Hxf/BBP/ir+3e8JTFQBFOiLNdFtB9KZWZmIExheXRvbiA8amxheXRvbkBzYW1iYS5vcmc+iQI4BBM BAgAiBQJOldK9AhsDBgsJCAcDAgYVCAIJCgsEFgIDAQIeAQIXgAAKCRAADmhBGVaCFWgWD/0ZRi4h N9FK2BdQs9RwNnFZUr7JidAWfCrs37XrA/56olQl3ojn0fQtrP4DbTmCuh0SfMijB24psy1GnkPep naQ6VRf7Dxg/Y8muZELSOtsv2CKt3/02J1BBitrkkqmHyni5fLLYYg6fub0T/8Kwo1qGPdu1hx2BQ RERYtQ/S5d/T0cACdlzi6w8rs5f09hU9Tu4qV1JLKmBTgUWKN969HPRkxiojLQziHVyM/weR5Reu6 FZVNuVBGqBD+sfk/c98VJHjsQhYJijcsmgMb1NohAzwrBKcSGKOWJToGEO/1RkIN8tqGnYNp2G+aR 685D0chgTl1WzPRM6mFG1+n2b2RR95DxumKVpwBwdLPoCkI24JkeDJ7lXSe3uFWISstFGt0HL8Eew P8RuGC8s5h7Ct91HMNQTbjgA+Vi1foWUVXpEintAKgoywaIDlJfTZIl6Ew8ETN/7DLy8bXYgq0Xzh aKg3CnOUuGQV5/nl4OAX/3jocT5Cz/OtAiNYj5mLPeL5z2ZszjoCAH6caqsF2oLyAnLqRgDgR+wTQ T6gMhr2IRsl+cp8gPHBwQ4uZMb+X00c/Amm9VfviT+BI7B66cnC7Zv6Gvmtu2rEjWDGWPqUgccB7h dMKnKDthkA227/82tYoFiFMb/NwtgGrn5n2vwJyKN6SEoygGrNt0SI84y6hEVbQlSmVmZiBMYXl0b 24gPGpsYXl0b25AcHJpbWFyeWRhdGEuY29tPokCOQQTAQIAIwUCU4xmKQIbAwcLCQgHAwIBBhUIAg kKCwQWAgMBAh4BAheAAAoJEAAOaEEZVoIV1H0P/j4OUTwFd7BBbpoSp695qb6HqCzWMuExsp8nZjr uymMaeZbGr3OWMNEXRI1FWNHMtcMHWLP/RaDqCJil28proO+PQ/yPhsr2QqJcW4nr91tBrv/MqItu AXLYlsgXqp4BxLP67bzRJ1Bd2x0bWXurpEXY//VBOLnODqThGEcL7jouwjmnRh9FTKZfBDpFRaEfD FOXIfAkMKBa/c9TQwRpx2DPsl3eFWVCNuNGKeGsirLqCxUg5kWTxEorROppz9oU4HPicL6rRH22Ce 6nOAON2vHvhkUuO3GbffhrcsPD4DaYup4ic+DxWm+DaSSRJ+e1yJvwi6NmQ9P9UAuLG93S2MdNNbo sZ9P8k2mTOVKMc+GooI9Ve/vH8unwitwo7ORMVXhJeU6Q0X7zf3SjwDq2lBhn1DSuTsn2DbsNTiDv qrAaCvbsTsw+SZRwF85eG67eAwouYk+dnKmp1q57LDKMyzysij2oDKbcBlwB/TeX16p8+LxECv51a sjS9TInnipssssUDrHIvoTTXWcz7Y5wIngxDFwT8rPY3EggzLGfK5Zx2Q5S/N0FfmADmKknG/D8qG IcJE574D956tiUDKN4I+/g125ORR1v7bP+OIaayAvq17RP+qcAqkxc0x8iCYVCYDouDyNvWPGRhbL UO7mlBpjW9jK9e2fvZY9iw3QzIPGKtClKZWZmIExheXRvbiA8amVmZi5sYXl0b25AcHJpbWFyeWRh dGEuY29tPokCOQQTAQIAIwUCU4xmUAIbAwcLCQgHAwIBBhUIAgkKCwQWAgMBAh4BAheAAAoJEAAOa EEZVoIVzJoQALFCS6n/FHQS+hIzHIb56JbokhK0AFqoLVzLKzrnaeXhE5isWcVg0eoV2oTScIwUSU apy94if69tnUo4Q7YNt8/6yFM6hwZAxFjOXR0ciGE3Q+Z1zi49Ox51yjGMQGxlakV9ep4sV/d5a50 M+LFTmYSAFp6HY23JN9PkjVJC4PUv5DYRbOZ6Y1+TfXKBAewMVqtwT1Y+LPlfmI8dbbbuUX/kKZ5d dhV2736fgyfpslvJKYl0YifUOVy4D1G/oSycyHkJG78OvX4JKcf2kKzVvg7/Rnv+AueCfFQ6nGwPn 0P91I7TEOC4XfZ6a1K3uTp4fPPs1Wn75X7K8lzJP/p8lme40uqwAyBjk+IA5VGd+CVRiyJTpGZwA0 jwSYLyXboX+Dqm9pSYzmC9+/AE7lIgpWj+3iNisp1SWtHc4pdtQ5EU2SEz8yKvDbD0lNDbv4ljI7e flPsvN6vOrxz24mCliEco5DwhpaaSnzWnbAPXhQDWb/lUgs/JNk8dtwmvWnqCwRqElMLVisAbJmC0 BhZ/Ab4sph3EaiZfdXKhiQqSGdK4La3OTJOJYZphPdGgnkvDV9Pl1QZ0ijXQrVIy3zd6VCNaKYq7B AKidn5g/2Q8oio9Tf4XfdZ9dtwcB+bwDJFgvvDYaZ5bI3ln4V3EyW5i2NfXazz/GA/I/ZtbsigCFc 8ftCBKZWZmIExheXRvbiA8amxheXRvbkBrZXJuZWwub3JnPokCOAQTAQIAIgUCWe8u6AIbAwYLCQg HAwIGFQgCCQoLBBYCAwECHgECF4AACgkQAA5oQRlWghUuCg/+Lb/xGxZD2Q1oJVAE37uW308UpVSD 2tAMJUvFTdDbfe3zKlPDTuVsyNsALBGclPLagJ5ZTP+Vp2irAN9uwBuacBOTtmOdz4ZN2tdvNgozz uxp4CHBDVzAslUi2idy+xpsp47DWPxYFIRP3M8QG/aNW052LaPc0cedYxp8+9eiVUNpxF4SiU4i9J DfX/sn9XcfoVZIxMpCRE750zvJvcCUz9HojsrMQ1NFc7MFT1z3MOW2/RlzPcog7xvR5ENPH19ojRD CHqumUHRry+RF0lH00clzX/W8OrQJZtoBPXv9ahka/Vp7kEulcBJr1cH5Wz/WprhsIM7U9pse1f1g Yy9YbXtWctUz8uvDR7shsQxAhX3qO7DilMtuGo1v97I/Kx4gXQ52syh/w6EBny71CZrOgD6kJwPVV AaM1LRC28muq91WCFhs/nzHozpbzcheyGtMUI2Ao4K6mnY+3zIuXPygZMFr9KXE6fF7HzKxKuZMJO aEZCiDOq0anx6FmOzs5E6Jqdpo/mtI8beK+BE7Va6ni7YrQlnT0i3vaTVMTiCThbqsB20VrbMjlhp f8lfK1XVNbRq/R7GZ9zHESlsa35ha60yd/j3pu5hT2xyy8krV8vGhHvnJ1XRMJBAB/UYb6FyC7S+m QZIQXVeAA+smfTT0tDrisj1U5x6ZB9b3nBg65kc= Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.56.2 (3.56.2-1.fc42) Precedence: bulk X-Mailing-List: linux-nfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Tue, 2025-09-02 at 20:10 +0800, Li Lingfeng wrote: > Hi, >=20 > =E5=9C=A8 2025/9/2 18:21, Jeff Layton =E5=86=99=E9=81=93: > > On Tue, 2025-09-02 at 10:22 +0800, Li Lingfeng wrote: > > > When file access conflicts occur between clients, the server recalls > > > delegations. If the client holding delegation fails to return it afte= r > > > a recall, nfs4_laundromat adds the delegation to cl_revoked list. > > > This causes subsequent SEQUENCE operations to set the > > > SEQ4_STATUS_RECALLABLE_STATE_REVOKED flag, forcing the client to > > > validate all delegations and return the revoked one. > > >=20 > > > However, if the client fails to return the delegation due to a timeou= t > > > after receiving the recall or a server bug, the delegation remains in= the > > > server's cl_revoked list. The client marks it revoked and won't find = it > > > upon detecting SEQ4_STATUS_RECALLABLE_STATE_REVOKED. This leads to a = loop: > > > the server persistently sets SEQ4_STATUS_RECALLABLE_STATE_REVOKED, an= d the > > > client repeatedly tests all delegations, severely impacting performan= ce > > > when numerous delegations exist. > > >=20 > > It is a performance impact, but I don't get the "loop" here. Are you > > saying that this problem compounds itself? That testing all delegations > > causes others to be revoked? > The delegation will be removed from server->delegations in client after > NFSPROC4_CLNT_DELEGRETURN is performed. > nfs4_delegreturn_done > =C2=A0nfs_delegation_mark_returned > =C2=A0 nfs_detach_delegation > =C2=A0 =C2=A0nfs_detach_delegation_locked > =C2=A0 =C2=A0 list_del_rcu // remove delegation from server->delegations >=20 > From the client's perspective, the delegation has been returned, but on > the server side, it is left in the cl_revoked list.[1]. >=20 > Subsequently, every sequence from the client will be flagged with > SEQ4_STATUS_RECALLABLE_STATE_REVOKED as long as cl_revoked remains=20 > non-empty. > nfsd4_sequence > =C2=A0seq->status_flags |=3D SEQ4_STATUS_RECALLABLE_STATE_REVOKED >=20 > When the client detects SEQ4_STATUS_RECALLABLE_STATE_REVOKED while > processing a sequence result, it sets NFS_DELEGATION_TEST_EXPIRED for all > delegations and wakes up the state manager for handling. > nfs41_sequence_done > =C2=A0nfs41_sequence_process > =C2=A0 nfs41_handle_sequence_flag_errors > =C2=A0 =C2=A0nfs41_handle_recallable_state_revoked > =C2=A0 =C2=A0 nfs_test_expired_all_delegations > =C2=A0 =C2=A0 =C2=A0nfs_mark_test_expired_all_delegations > =C2=A0 =C2=A0 =C2=A0 nfs_delegation_mark_test_expired_server > =C2=A0 =C2=A0 =C2=A0 =C2=A0// set NFS_DELEGATION_TEST_EXPIRED for delega= tions in=20 > server->delegations > =C2=A0 =C2=A0 =C2=A0nfs4_schedule_state_manager >=20 > The state manager tests all delegations except the one that was returned, > as it is no longer in server->delegations. > nfs4_state_manager > =C2=A0nfs4_begin_drain_session > =C2=A0nfs_reap_expired_delegations > =C2=A0 nfs_server_reap_expired_delegations > =C2=A0 =C2=A0// test delegations in server->delegations >=20 > There may be a loop: > 1) send a sequence(client) > 2) return SEQ4_STATUS_RECALLABLE_STATE_REVOKED(server) > 3) set NFS_DELEGATION_TEST_EXPIRED for all delegations(client) > 4) test all delegations by state manager(client) > 5) send another sequence(client) >=20 > The state manager's traversal of delegations occurs between > nfs4_begin_drain_session and nfs4_end_drain_session. Non-privileged reque= sts > will be blocked because the NFS4_SLOT_TBL_DRAINING flag is set. If there = are > many delegations to traverse, this blocking time can be relatively long. > > > Since abnormal delegations are removed from flc_lease via nfs4_laundr= omat > > > --> revoke_delegation --> destroy_unhashed_deleg --> > > > nfs4_unlock_deleg_lease --> kernel_setlease, and do not block new ope= n > > > requests indefinitely, retaining such a delegation on the server is > > > unnecessary. > > >=20 > > > Reported-by: Zhang Jian > > > Fixes: 3bd64a5ba171 ("nfsd4: implement SEQ4_STATUS_RECALLABLE_STATE_R= EVOKED") > > > Closes: https://lore.kernel.org/all/ff8debe9-6877-4cf7-ba29-fc98eae0f= fa0@huawei.com/ > > > Signed-off-by: Li Lingfeng > > > --- > > > fs/nfsd/nfs4state.c | 11 +++++++++++ > > > 1 file changed, 11 insertions(+) > > >=20 > > > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c > > > index 88c347957da5..aa65a685dbb9 100644 > > > --- a/fs/nfsd/nfs4state.c > > > +++ b/fs/nfsd/nfs4state.c > > > @@ -4326,6 +4326,8 @@ nfsd4_sequence(struct svc_rqst *rqstp, struct n= fsd4_compound_state *cstate, > > > int buflen; > > > struct net *net =3D SVC_NET(rqstp); > > > struct nfsd_net *nn =3D net_generic(net, nfsd_net_id); > > > + struct list_head *pos, *next; > > > + struct nfs4_delegation *dp; > > > =20 > > > if (resp->opcnt !=3D 1) > > > return nfserr_sequence_pos; > > > @@ -4470,6 +4472,15 @@ nfsd4_sequence(struct svc_rqst *rqstp, struct = nfsd4_compound_state *cstate, > > > default: > > > seq->status_flags =3D 0; > > > } > > > + if (!list_empty(&clp->cl_revoked)) { > > > + list_for_each_safe(pos, next, &clp->cl_revoked) { > > > + dp =3D list_entry(pos, struct nfs4_delegation, dl_recall_lru); > > > + if (dp->dl_time < (ktime_get_boottime_seconds() - 2 * nn->nfsd4_l= ease)) { > > > + list_del_init(&dp->dl_recall_lru); > > > + nfs4_put_stid(&dp->dl_stid); > > > + } > > > + } FYI: this list is protected by the clp->cl_lock. You need to hold it to do this list walk. > > > + } > > > if (!list_empty(&clp->cl_revoked)) > > > seq->status_flags |=3D SEQ4_STATUS_RECALLABLE_STATE_REVOKED; > > > if (atomic_read(&clp->cl_admin_revoked)) > > This seems like a violation of the spec. AIUI, the server is required > > to hang onto a record of the delegation until the client does the > > TEST_STATEID/FREE_STATEID dance to remove it. Just discarding them like > > this seems wrong. > Our expected outcome was that the client would release the abnormal > delegation via TEST_STATEID/FREE_STATEID upon detecting its invalidity. > However, this problematic delegation is no longer present in the > client's server->delegations list=E2=80=94whether due to client-side time= outs or > the server-side bug [1]. > >=20 > > Should we instead just administratively evict the client since it's > > clearly not behaving right in this case? > Thanks for the suggestion. While administratively evicting the client wou= ld > certainly resolve the immediate delegation issue, I'm concerned that=20 > approach > might be a bit heavy-handed. > The problematic behavior seems isolated to a single delegation. Meanwhile= , > the client itself likely has numerous other open files and active state o= n > the server. Forcing a complete client reconnect would tear down all that > state, which could cause significant application disruption and be percei= ved > as a service outage from the client's perspective. >=20 > [1]=20 > https://lore.kernel.org/all/de669327-c93a-49e5-a53b-bda9e67d34a2@huawei.c= om/ >=20 > Thanks, > Lingfeng Ok, I get the problem, but I still disagree with the solution. I don't think we can just time these things out. Ideally we'd close the race window, but the sc_status field is protected by the global state_lock and I don't think we want to take it in revoke_delegation. The best solution I can see is to have destroy_delegation() unconditionally set SC_STATUS_CLOSED, and then you can do the list walk above, but checking for that flag instead of testing for a timeout. I'm still not thrilled with this solution though. It makes SEQUENCE a bit more heavyweight than I'd like. I'm starting to think that we need to rework the overall delegation locking, but that's an ugly problem to tackle.=20 --=20 Jeff Layton