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 C40452EA47C; Wed, 3 Sep 2025 12:15:18 +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=1756901720; cv=none; b=oL0Vl6Y2HjsK8szW06nfyrm3NpE7PQkS5buNLvTCvyYxr0Qsk6tp+cMHESbp/iYYB0Gc9e8eJPs43woC1vEXelm+h1kBKNvvHa4DEPEk9wCVk+BdM/QhVQuF6j4HBjFnO080WdYoooESmpjyTtMsqwXYFDvj40xSlHhQ1ndphss= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756901720; c=relaxed/simple; bh=RstKJcmAVnx14GdBD7LLbE76faK90zQc80sElX+VrcI=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=Yb5NgQ0s5IgibvM83pSCzapyAL4KwRns4DAF7tyZdVYbWI1YqKN9xbcmZeCG4WLIXsF+RSVyiuydmbag0rnUsvzr7fbwQDgn9Uhc2PdjIj7qd7ZpQWOiJIVHlDUg4DLtoXLGy9U4+disCCEPPkvQgilfmJ60CzWG2d+YsRoiqIY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=dH2DKnyC; 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="dH2DKnyC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1B2EAC4CEF0; Wed, 3 Sep 2025 12:15:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1756901718; bh=RstKJcmAVnx14GdBD7LLbE76faK90zQc80sElX+VrcI=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=dH2DKnyCRMrRfrXV+8mElBox2nKQHIrmWAQUM0/dXnyiWdXUqzOogJ0W6CJCJXJp0 83mZS03+edPWOPlFZrKQFchclhpYxaoR+Zu7hAY2L+97Bg2YWEb3cXZBKLRmkL2cXq cWrh82WdVdHAA7+ci/MuORgyKfBXHGKWUO/OJytPZBur8qZXj+XOHmX7gsUDjejXO+ f4pMDxUaS4Y3tCwL53vZ5XDd3he3iAeitNcwl2omzjf6sPjuADh/v9J2Am0z1U2Aut 4z1rRSNaBDcSKVqj9fksBgDRV47gp3bquaPVajLnq/v+nQDtW1LJcyQqvA+wxj6lvO VN9DktoWHBDXw== Message-ID: <837da22b428e5a7cbda1f56868cbfe23e89dccf7.camel@kernel.org> Subject: Re: [PATCH v2] 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, bcodding@redhat.com Date: Wed, 03 Sep 2025 08:15:16 -0400 In-Reply-To: <20250903115918.788159-1-lilingfeng3@huawei.com> References: <20250903115918.788159-1-lilingfeng3@huawei.com> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw 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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 Wed, 2025-09-03 at 19:59 +0800, Li Lingfeng wrote: > When file access conflicts occur between clients, the server recalls > delegations. If the client holding delegation fails to return it after > 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 like this: > nfs4_laundromat nfsd4_delegreturn > unhash_delegation_locked > list_add // add dp to reaplist > // by dl_recall_lru > list_del_init // delete dp from > // reaplist > destroy_delegation > unhash_delegation_locked > // do nothing but return false > revoke_delegation > list_add // add dp to cl_revoked > // by dl_recall_lru >=20 > The delegation will remain in the server's cl_revoked list while 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, and th= e > client repeatedly tests all delegations, severely impacting performance > when numerous delegations exist. >=20 > Since abnormal delegations are removed from flc_lease via nfs4_laundromat > --> revoke_delegation --> destroy_unhashed_deleg --> > nfs4_unlock_deleg_lease --> kernel_setlease, and do not block new open > requests indefinitely, retaining such a delegation on the server is > unnecessary. >=20 > Reported-by: Zhang Jian > Fixes: 3bd64a5ba171 ("nfsd4: implement SEQ4_STATUS_RECALLABLE_STATE_REVOK= ED") > Closes: https://lore.kernel.org/all/ff8debe9-6877-4cf7-ba29-fc98eae0ffa0@= huawei.com/ > Signed-off-by: Li Lingfeng > --- > Changes in v2: > 1) Set SC_STATUS_CLOSED unconditionally in destroy_delegation(); > 2) Determine whether to remove the delegation based on SC_STATUS_CLOSED= , > rather than by timeout; > 3) Modify the commit message. > fs/nfsd/nfs4state.c | 20 ++++++++++++++++++++ > 1 file changed, 20 insertions(+) >=20 > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c > index 88c347957da5..bb9e1df4e41f 100644 > --- a/fs/nfsd/nfs4state.c > +++ b/fs/nfsd/nfs4state.c > @@ -1336,6 +1336,11 @@ static void destroy_delegation(struct nfs4_delegat= ion *dp) > =20 > spin_lock(&state_lock); > unhashed =3D unhash_delegation_locked(dp, SC_STATUS_CLOSED); > + /* > + * Unconditionally set SC_STATUS_CLOSED, regardless of whether the > + * delegation is hashed, to mark the current delegation as invalid. > + */ > + dp->dl_stid.sc_status |=3D SC_STATUS_CLOSED; > spin_unlock(&state_lock); > if (unhashed) > destroy_unhashed_deleg(dp); > @@ -4326,6 +4331,8 @@ nfsd4_sequence(struct svc_rqst *rqstp, struct nfsd4= _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 nit: These could be moved inside the if statement below. > if (resp->opcnt !=3D 1) > return nfserr_sequence_pos; > @@ -4470,6 +4477,19 @@ nfsd4_sequence(struct svc_rqst *rqstp, struct nfsd= 4_compound_state *cstate, > default: > seq->status_flags =3D 0; > } I wouldn't mind a comment here that explains why we have to do this. This is the sort of thing that will have us all scratching our heads in a few years. > + if (!list_empty(&clp->cl_revoked)) { > + spin_lock(&clp->cl_lock); > + list_for_each_safe(pos, next, &clp->cl_revoked) { > + dp =3D list_entry(pos, struct nfs4_delegation, dl_recall_lru); > + if (dp->dl_stid.sc_status & SC_STATUS_CLOSED) { > + list_del_init(&dp->dl_recall_lru); > + spin_unlock(&clp->cl_lock); > + nfs4_put_stid(&dp->dl_stid); > + spin_lock(&clp->cl_lock); > + } > + } > + spin_unlock(&clp->cl_lock); > + } nit: I'd move the if statement below inside the above if statement. No need to check list_empty() twice if it was empty the first time. Maybe the compiler papers over this and only does it once? > if (!list_empty(&clp->cl_revoked)) > seq->status_flags |=3D SEQ4_STATUS_RECALLABLE_STATE_REVOKED; > if (atomic_read(&clp->cl_admin_revoked)) Otherwise, this looks great. Thanks for the patch! Reviewed-by: Jeff Layton