From patchwork Thu Jun 3 18:14:38 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dai Ngo X-Patchwork-Id: 12297797 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C9232C47096 for ; Thu, 3 Jun 2021 18:14:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ABE6061358 for ; Thu, 3 Jun 2021 18:14:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229695AbhFCSQb (ORCPT ); Thu, 3 Jun 2021 14:16:31 -0400 Received: from userp2120.oracle.com ([156.151.31.85]:60272 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229576AbhFCSQb (ORCPT ); Thu, 3 Jun 2021 14:16:31 -0400 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 153IA55T039622; Thu, 3 Jun 2021 18:14:45 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : cc : subject : date : message-id : mime-version : content-transfer-encoding; s=corp-2020-01-29; bh=ZuNV20POdSAvn0UVoDbQ26cMYJ0y/HkEBAGPw3kPGFI=; b=jZdEoENUyx2f0AMiTxkVcZhdx02okbr3Hcib+fs/lzMz3puy1mz/7A1bVOBC2BEulK6C CZ6cyYPHzEb2Xo6QKsS6tQ6XS5BiyFjvdGu9XmErv0/0CZED+x2pJKb3vUd9gEGB+fjR Ybxv/hCt2VUrnjNo+Sj3rgnqPYjOKuSbLfkFiizU2j5dKcMFfuDefj8Gwtt6FM3bLVmF lM5VncaHC9feVM8HqW+MSgZJ/xERlMCOi5WWE9beklP9fjAo4s5nq1Ug8uZLrVvv78oX rsdGzWiMywUmXJMCgRcnfG+kLTW5w0UIFamuTkmqL/yOrw3IEEVoO9C9QuvTPjNvbcFP ZA== Received: from aserp3030.oracle.com (aserp3030.oracle.com [141.146.126.71]) by userp2120.oracle.com with ESMTP id 38ue8pm3e4-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 03 Jun 2021 18:14:44 +0000 Received: from pps.filterd (aserp3030.oracle.com [127.0.0.1]) by aserp3030.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 153IAbSQ116367; Thu, 3 Jun 2021 18:14:44 GMT Received: from pps.reinject (localhost [127.0.0.1]) by aserp3030.oracle.com with ESMTP id 38ubnf35p9-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 03 Jun 2021 18:14:44 +0000 Received: from aserp3030.oracle.com (aserp3030.oracle.com [127.0.0.1]) by pps.reinject (8.16.0.36/8.16.0.36) with SMTP id 153IEh40127570; Thu, 3 Jun 2021 18:14:43 GMT Received: from userp3020.oracle.com (ksplice-shell2.us.oracle.com [10.152.118.36]) by aserp3030.oracle.com with ESMTP id 38ubnf35p7-1; Thu, 03 Jun 2021 18:14:43 +0000 From: Dai Ngo To: bfields@fieldses.org Cc: chuck.lever@oracle.com, linux-nfs@vger.kernel.org Subject: [PATCH RFC 1/1] nfsd: Initial implementation of NFSv4 Courteous Server Date: Thu, 3 Jun 2021 14:14:38 -0400 Message-Id: <20210603181438.109851-1-dai.ngo@oracle.com> X-Mailer: git-send-email 2.20.1.1226.g1595ea5.dirty MIME-Version: 1.0 X-Proofpoint-GUID: PiLL2s4VXRpjrvXL2fVDZpQeyFdCMArF X-Proofpoint-ORIG-GUID: PiLL2s4VXRpjrvXL2fVDZpQeyFdCMArF X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=10004 signatures=668682 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxscore=0 impostorscore=0 malwarescore=0 adultscore=0 suspectscore=0 lowpriorityscore=0 spamscore=0 bulkscore=0 phishscore=0 priorityscore=1501 clxscore=1015 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104190000 definitions=main-2106030123 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org Currently an NFSv4 client must maintain its lease by using the at least one of the state tokens or if nothing else, by issuing a RENEW (4.0), or a singleton SEQUENCE (4.1) at least once during each lease period. If the client fails to renew the lease, for any reason, the Linux server expunges the state tokens immediately upon detection of the "failure to renew the lease" condition and begins returning NFS4ERR_EXPIRED if the client should reconnect and attempt to use the (now) expired state. The default lease period for the Linux server is 90 seconds. The typical client cuts that in half and will issue a lease renewing operation every 45 seconds. The 90 second lease period is very short considering the potential for moderately long term network partitions. A network partition refers to any loss of network connectivity between the NFS client and the NFS server, regardless of its root cause. This includes NIC failures, NIC driver bugs, network misconfigurations & administrative errors, routers & switches crashing and/or having software updates applied, even down to cables being physically pulled. In most cases, these network failures are transient, although the duration is unknown. A server which does not immediately expunge the state on lease expiration is known as a Courteous Server. A Courteous Server continues to recognize previously generated state tokens as valid until conflict arises between the expired state and the requests from another client, or the server reboots. The initial implementation of the Courteous Server will do the following: . when the laundromat thread detects an expired client and if that client still has established states on the Linux server then marks the client as a COURTESY_CLIENT and skips destroying the client and all its states, otherwise destroy the client as usual. . detects conflict of OPEN request with a COURTESY_CLIENT, destroys the expired client and all its states, skips the delegation recall then allows the conflicting request to succeed. . detects conflict of LOCK/LOCKT request with a COURTESY_CLIENT, destroys the expired client and all its states then allows the conflicting request to succeed. To be done: . fix a problem with 4.1 where the Linux server keeps returning SEQ4_STATUS_CB_PATH_DOWN in the successful SEQUENCE reply, after the expired client re-connects, causing the client to keep sending BCTS requests to server. . handle OPEN conflict with share reservations. . instead of destroy the client anf all its state on conflict, only destroy the state that is conflicted with the current request. . destroy the COURTESY_CLIENT either after a fixed period of time to release resources or as reacting to memory pressure. Signed-off-by: Dai Ngo --- fs/nfsd/nfs4state.c | 94 +++++++++++++++++++++++++++++++++++++++++++--- fs/nfsd/state.h | 1 + include/linux/sunrpc/svc.h | 1 + 3 files changed, 91 insertions(+), 5 deletions(-) diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index b517a8794400..969995872752 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -171,6 +171,7 @@ renew_client_locked(struct nfs4_client *clp) list_move_tail(&clp->cl_lru, &nn->client_lru); clp->cl_time = ktime_get_boottime_seconds(); + clear_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags); } static void put_client_renew_locked(struct nfs4_client *clp) @@ -4610,6 +4611,38 @@ static void nfsd_break_one_deleg(struct nfs4_delegation *dp) nfsd4_run_cb(&dp->dl_recall); } +/* + * Set rq_conflict_client if the conflict client have expired + * and return true, otherwise return false. + */ +static bool +nfsd_set_conflict_client(struct nfs4_delegation *dp) +{ + struct svc_rqst *rqst; + struct nfs4_client *clp; + struct nfsd_net *nn; + bool ret; + + if (!i_am_nfsd()) + return false; + rqst = kthread_data(current); + if (rqst->rq_prog != NFS_PROGRAM || rqst->rq_vers < 4) + return false; + rqst->rq_conflict_client = NULL; + clp = dp->dl_recall.cb_clp; + nn = net_generic(clp->net, nfsd_net_id); + spin_lock(&nn->client_lock); + + if (test_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags) && + !mark_client_expired_locked(clp)) { + rqst->rq_conflict_client = clp; + ret = true; + } else + ret = false; + spin_unlock(&nn->client_lock); + return ret; +} + /* Called from break_lease() with i_lock held. */ static bool nfsd_break_deleg_cb(struct file_lock *fl) @@ -4618,6 +4651,8 @@ nfsd_break_deleg_cb(struct file_lock *fl) struct nfs4_delegation *dp = (struct nfs4_delegation *)fl->fl_owner; struct nfs4_file *fp = dp->dl_stid.sc_file; + if (nfsd_set_conflict_client(dp)) + return false; trace_nfsd_deleg_break(&dp->dl_stid.sc_stateid); /* @@ -5237,6 +5272,22 @@ static void nfsd4_deleg_xgrade_none_ext(struct nfsd4_open *open, */ } +static bool +nfs4_destroy_courtesy_client(struct nfs4_client *clp) +{ + struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id); + + spin_lock(&nn->client_lock); + if (!test_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags) || + mark_client_expired_locked(clp)) { + spin_unlock(&nn->client_lock); + return false; + } + spin_unlock(&nn->client_lock); + expire_client(clp); + return true; +} + __be32 nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nfsd4_open *open) { @@ -5286,7 +5337,13 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf goto out; } } else { + rqstp->rq_conflict_client = NULL; status = nfs4_get_vfs_file(rqstp, fp, current_fh, stp, open); + if (status == nfserr_jukebox && rqstp->rq_conflict_client) { + if (nfs4_destroy_courtesy_client(rqstp->rq_conflict_client)) + status = nfs4_get_vfs_file(rqstp, fp, current_fh, stp, open); + } + if (status) { stp->st_stid.sc_type = NFS4_CLOSED_STID; release_open_stateid(stp); @@ -5472,6 +5529,8 @@ nfs4_laundromat(struct nfsd_net *nn) }; struct nfs4_cpntf_state *cps; copy_stateid_t *cps_t; + struct nfs4_stid *stid; + int id = 0; int i; if (clients_still_reclaiming(nn)) { @@ -5495,6 +5554,15 @@ nfs4_laundromat(struct nfsd_net *nn) clp = list_entry(pos, struct nfs4_client, cl_lru); if (!state_expired(<, clp->cl_time)) break; + + spin_lock(&clp->cl_lock); + stid = idr_get_next(&clp->cl_stateids, &id); + spin_unlock(&clp->cl_lock); + if (stid) { + /* client still has states */ + set_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags); + continue; + } if (mark_client_expired_locked(clp)) { trace_nfsd_clid_expired(&clp->cl_clientid); continue; @@ -6440,7 +6508,7 @@ static const struct lock_manager_operations nfsd_posix_mng_ops = { .lm_put_owner = nfsd4_fl_put_owner, }; -static inline void +static inline int nfs4_set_lock_denied(struct file_lock *fl, struct nfsd4_lock_denied *deny) { struct nfs4_lockowner *lo; @@ -6453,6 +6521,8 @@ nfs4_set_lock_denied(struct file_lock *fl, struct nfsd4_lock_denied *deny) /* We just don't care that much */ goto nevermind; deny->ld_clientid = lo->lo_owner.so_client->cl_clientid; + if (nfs4_destroy_courtesy_client(lo->lo_owner.so_client)) + return -EAGAIN; } else { nevermind: deny->ld_owner.len = 0; @@ -6467,6 +6537,7 @@ nfs4_set_lock_denied(struct file_lock *fl, struct nfsd4_lock_denied *deny) deny->ld_type = NFS4_READ_LT; if (fl->fl_type != F_RDLCK) deny->ld_type = NFS4_WRITE_LT; + return 0; } static struct nfs4_lockowner * @@ -6734,6 +6805,7 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, unsigned int fl_flags = FL_POSIX; struct net *net = SVC_NET(rqstp); struct nfsd_net *nn = net_generic(net, nfsd_net_id); + bool retried = false; dprintk("NFSD: nfsd4_lock: start=%Ld length=%Ld\n", (long long) lock->lk_offset, @@ -6860,7 +6932,7 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, list_add_tail(&nbl->nbl_lru, &nn->blocked_locks_lru); spin_unlock(&nn->blocked_locks_lock); } - +again: err = vfs_lock_file(nf->nf_file, F_SETLK, file_lock, conflock); switch (err) { case 0: /* success! */ @@ -6875,7 +6947,12 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, case -EAGAIN: /* conflock holds conflicting lock */ status = nfserr_denied; dprintk("NFSD: nfsd4_lock: conflicting lock found!\n"); - nfs4_set_lock_denied(conflock, &lock->lk_denied); + + /* try again if conflict with courtesy client */ + if (nfs4_set_lock_denied(conflock, &lock->lk_denied) == -EAGAIN && !retried) { + retried = true; + goto again; + } break; case -EDEADLK: status = nfserr_deadlock; @@ -6962,6 +7039,8 @@ nfsd4_lockt(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, struct nfs4_lockowner *lo = NULL; __be32 status; struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id); + bool retried = false; + int ret; if (locks_in_grace(SVC_NET(rqstp))) return nfserr_grace; @@ -7010,14 +7089,19 @@ nfsd4_lockt(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, file_lock->fl_end = last_byte_offset(lockt->lt_offset, lockt->lt_length); nfs4_transform_lock_offset(file_lock); - +again: status = nfsd_test_lock(rqstp, &cstate->current_fh, file_lock); if (status) goto out; if (file_lock->fl_type != F_UNLCK) { status = nfserr_denied; - nfs4_set_lock_denied(file_lock, &lockt->lt_denied); + ret = nfs4_set_lock_denied(file_lock, &lockt->lt_denied); + if (ret == -EAGAIN && !retried) { + retried = true; + fh_clear_wcc(&cstate->current_fh); + goto again; + } } out: if (lo) diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h index e73bdbb1634a..bdc3605e3722 100644 --- a/fs/nfsd/state.h +++ b/fs/nfsd/state.h @@ -345,6 +345,7 @@ struct nfs4_client { #define NFSD4_CLIENT_UPCALL_LOCK (5) /* upcall serialization */ #define NFSD4_CLIENT_CB_FLAG_MASK (1 << NFSD4_CLIENT_CB_UPDATE | \ 1 << NFSD4_CLIENT_CB_KILL) +#define NFSD4_CLIENT_COURTESY (6) /* be nice to expired client */ unsigned long cl_flags; const struct cred *cl_cb_cred; struct rpc_clnt *cl_cb_client; diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h index e91d51ea028b..2f0382f9d0ff 100644 --- a/include/linux/sunrpc/svc.h +++ b/include/linux/sunrpc/svc.h @@ -304,6 +304,7 @@ struct svc_rqst { * net namespace */ void ** rq_lease_breaker; /* The v4 client breaking a lease */ + void *rq_conflict_client; }; #define SVC_NET(rqst) (rqst->rq_xprt ? rqst->rq_xprt->xpt_net : rqst->rq_bc_net)