From patchwork Mon Oct 30 01:08:35 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: NeilBrown X-Patchwork-Id: 13439950 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 39666C4332F for ; Mon, 30 Oct 2023 01:13:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229470AbjJ3BNW (ORCPT ); Sun, 29 Oct 2023 21:13:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52364 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231298AbjJ3BNV (ORCPT ); Sun, 29 Oct 2023 21:13:21 -0400 Received: from smtp-out2.suse.de (smtp-out2.suse.de [IPv6:2001:67c:2178:6::1d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DAECCBD for ; Sun, 29 Oct 2023 18:13:18 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 5D7301FE9E; Mon, 30 Oct 2023 01:13:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1698628397; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=jCo7VgihP+DB3cpAG6qtLT+OVGESU5LvlqGZWV2Rs1E=; b=tSpXZyqj70V+lAp6tbNz59Icd96dO6rt8eYe5HiasRiuuti6RhE+Ni8X/CilyoHDjIFnIT pX4+g+c3v+vO3NgYSqeegtTDL/tGyPmifZyEHSNtZowZpGPVm03Wreu5hmsuH8xwYJzJeT PzlnrsQOtfkqY80RCR3HdKASpDWrfPw= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1698628397; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=jCo7VgihP+DB3cpAG6qtLT+OVGESU5LvlqGZWV2Rs1E=; b=TGWt2YdTPZja+UdkxbaZHOYey2Cj0g/CWpdygECsOikintlGTXLS/Qc7bkkiGWeMCqUQwF vh6IMjoALGYXUTBQ== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 1174013460; Mon, 30 Oct 2023 01:13:14 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id vLJ8LSoDP2VkRwAAMHmgww (envelope-from ); Mon, 30 Oct 2023 01:13:14 +0000 From: NeilBrown To: Chuck Lever , Jeff Layton Cc: linux-nfs@vger.kernel.org, Olga Kornievskaia , Dai Ngo , Tom Talpey Subject: [PATCH 2/5] svc: don't hold reference for poolstats, only mutex. Date: Mon, 30 Oct 2023 12:08:35 +1100 Message-ID: <20231030011247.9794-3-neilb@suse.de> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231030011247.9794-1-neilb@suse.de> References: <20231030011247.9794-1-neilb@suse.de> MIME-Version: 1.0 Authentication-Results: smtp-out2.suse.de; none X-Spamd-Result: default: False [-2.10 / 50.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; R_MISSING_CHARSET(2.50)[]; MIME_GOOD(-0.10)[text/plain]; BROKEN_CONTENT_TYPE(1.50)[]; RCPT_COUNT_FIVE(0.00)[6]; NEURAL_HAM_LONG(-3.00)[-1.000]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-1.00)[-1.000]; MID_CONTAINS_FROM(1.00)[]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; RCVD_COUNT_TWO(0.00)[2]; RCVD_TLS_ALL(0.00)[]; BAYES_HAM(-3.00)[100.00%] Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org A future patch will remove refcounting on svc_serv as it is of little use. It is currently used to keep the svc around while the pool_stats file is open. Change this to get the pointer, protected by the mutex, only in seq_start, and the release the mutex in seq_stop. This means that if the nfsd server is stopped and restarted while the pool_stats file it open, then some pool stats info could be from the first instance and some from the second. This might appear odd, but is unlikely to be a problem in practice. Signed-off-by: NeilBrown --- fs/nfsd/nfsctl.c | 2 +- fs/nfsd/nfssvc.c | 30 ++++++++--------------- include/linux/sunrpc/svc.h | 5 +++- net/sunrpc/svc_xprt.c | 49 ++++++++++++++++++++++++++++++++------ 4 files changed, 57 insertions(+), 29 deletions(-) diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c index 79efb1075f38..d78ae4452946 100644 --- a/fs/nfsd/nfsctl.c +++ b/fs/nfsd/nfsctl.c @@ -179,7 +179,7 @@ static const struct file_operations pool_stats_operations = { .open = nfsd_pool_stats_open, .read = seq_read, .llseek = seq_lseek, - .release = nfsd_pool_stats_release, + .release = svc_pool_stats_release, }; DEFINE_SHOW_ATTRIBUTE(nfsd_reply_cache_stats); diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c index 6c968c02cc29..203e1cfc1cad 100644 --- a/fs/nfsd/nfssvc.c +++ b/fs/nfsd/nfssvc.c @@ -1072,30 +1072,20 @@ bool nfssvc_encode_voidres(struct svc_rqst *rqstp, struct xdr_stream *xdr) return true; } -int nfsd_pool_stats_open(struct inode *inode, struct file *file) +static struct svc_serv *nfsd_get_serv(struct seq_file *s, bool start) { - int ret; - struct nfsd_net *nn = net_generic(inode->i_sb->s_fs_info, nfsd_net_id); - - mutex_lock(&nfsd_mutex); - if (nn->nfsd_serv == NULL) { + struct nfsd_net *nn = net_generic(file_inode(s->file)->i_sb->s_fs_info, + nfsd_net_id); + if (start) { + mutex_lock(&nfsd_mutex); + return nn->nfsd_serv; + } else { mutex_unlock(&nfsd_mutex); - return -ENODEV; + return NULL; } - svc_get(nn->nfsd_serv); - ret = svc_pool_stats_open(nn->nfsd_serv, file); - mutex_unlock(&nfsd_mutex); - return ret; } -int nfsd_pool_stats_release(struct inode *inode, struct file *file) +int nfsd_pool_stats_open(struct inode *inode, struct file *file) { - struct seq_file *seq = file->private_data; - struct svc_serv *serv = seq->private; - int ret = seq_release(inode, file); - - mutex_lock(&nfsd_mutex); - svc_put(serv); - mutex_unlock(&nfsd_mutex); - return ret; + return svc_pool_stats_open(nfsd_get_serv, file); } diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h index b10f987509cc..11acad6988a2 100644 --- a/include/linux/sunrpc/svc.h +++ b/include/linux/sunrpc/svc.h @@ -433,7 +433,10 @@ void svc_exit_thread(struct svc_rqst *); struct svc_serv * svc_create_pooled(struct svc_program *, unsigned int, int (*threadfn)(void *data)); int svc_set_num_threads(struct svc_serv *, struct svc_pool *, int); -int svc_pool_stats_open(struct svc_serv *serv, struct file *file); +int svc_pool_stats_open(struct svc_serv *(*get_serv)(struct seq_file *, bool), + struct file *file); +int svc_pool_stats_release(struct inode *inode, + struct file *file); void svc_process(struct svc_rqst *rqstp); void svc_process_bc(struct rpc_rqst *req, struct svc_rqst *rqstp); int svc_register(const struct svc_serv *, struct net *, const int, diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c index fee83d1024bc..2f99f7475b7b 100644 --- a/net/sunrpc/svc_xprt.c +++ b/net/sunrpc/svc_xprt.c @@ -1366,26 +1366,38 @@ EXPORT_SYMBOL_GPL(svc_xprt_names); /*----------------------------------------------------------------------------*/ +struct pool_private { + struct svc_serv *(*get_serv)(struct seq_file *, bool); + struct svc_serv *serv; +}; + static void *svc_pool_stats_start(struct seq_file *m, loff_t *pos) { unsigned int pidx = (unsigned int)*pos; - struct svc_serv *serv = m->private; + struct pool_private *pp = m->private; dprintk("svc_pool_stats_start, *pidx=%u\n", pidx); + pp->serv = pp->get_serv(m, true); + if (!pidx) return SEQ_START_TOKEN; - return (pidx > serv->sv_nrpools ? NULL : &serv->sv_pools[pidx-1]); + if (!pp->serv) + return NULL; + return (pidx > pp->serv->sv_nrpools ? NULL : &pp->serv->sv_pools[pidx-1]); } static void *svc_pool_stats_next(struct seq_file *m, void *p, loff_t *pos) { struct svc_pool *pool = p; - struct svc_serv *serv = m->private; + struct pool_private *pp = m->private; + struct svc_serv *serv = pp->serv; dprintk("svc_pool_stats_next, *pos=%llu\n", *pos); - if (p == SEQ_START_TOKEN) { + if (!serv) { + pool = NULL; + } else if (p == SEQ_START_TOKEN) { pool = &serv->sv_pools[0]; } else { unsigned int pidx = (pool - &serv->sv_pools[0]); @@ -1400,6 +1412,9 @@ static void *svc_pool_stats_next(struct seq_file *m, void *p, loff_t *pos) static void svc_pool_stats_stop(struct seq_file *m, void *p) { + struct pool_private *pp = m->private; + + pp->get_serv(m, false); } static int svc_pool_stats_show(struct seq_file *m, void *p) @@ -1427,15 +1442,35 @@ static const struct seq_operations svc_pool_stats_seq_ops = { .show = svc_pool_stats_show, }; -int svc_pool_stats_open(struct svc_serv *serv, struct file *file) +int svc_pool_stats_open(struct svc_serv *(*get_serv)(struct seq_file *, bool), + struct file *file) { + struct pool_private *pp; int err; + pp = kmalloc(sizeof(*pp), GFP_KERNEL); + if (!pp) + return -ENOMEM; + err = seq_open(file, &svc_pool_stats_seq_ops); - if (!err) - ((struct seq_file *) file->private_data)->private = serv; + if (!err) { + pp->get_serv = get_serv; + ((struct seq_file *) file->private_data)->private = pp; + } else + kfree(pp); + return err; } EXPORT_SYMBOL(svc_pool_stats_open); +int svc_pool_stats_release(struct inode *inode, struct file *file) +{ + struct seq_file *seq = file->private_data; + + kfree(seq->private); + seq->private = NULL; + return seq_release(inode, file); +} +EXPORT_SYMBOL(svc_pool_stats_release); + /*----------------------------------------------------------------------------*/