From patchwork Tue Oct 6 00:06:15 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Simmons X-Patchwork-Id: 11817949 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 3126E6CB for ; Tue, 6 Oct 2020 00:07:52 +0000 (UTC) Received: from pdx1-mailman02.dreamhost.com (pdx1-mailman02.dreamhost.com [64.90.62.194]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 124B5206F4 for ; Tue, 6 Oct 2020 00:07:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 124B5206F4 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lustre-devel-bounces@lists.lustre.org Received: from pdx1-mailman02.dreamhost.com (localhost [IPv6:::1]) by pdx1-mailman02.dreamhost.com (Postfix) with ESMTP id E1F552F5B14; Mon, 5 Oct 2020 17:07:15 -0700 (PDT) X-Original-To: lustre-devel@lists.lustre.org Delivered-To: lustre-devel-lustre.org@pdx1-mailman02.dreamhost.com Received: from smtp4.ccs.ornl.gov (smtp4.ccs.ornl.gov [160.91.203.40]) by pdx1-mailman02.dreamhost.com (Postfix) with ESMTP id 7812121FFE3 for ; Mon, 5 Oct 2020 17:06:38 -0700 (PDT) Received: from star.ccs.ornl.gov (star.ccs.ornl.gov [160.91.202.134]) by smtp4.ccs.ornl.gov (Postfix) with ESMTP id 5F7F310087F8; Mon, 5 Oct 2020 20:06:25 -0400 (EDT) Received: by star.ccs.ornl.gov (Postfix, from userid 2004) id 5E3AF2F0E5; Mon, 5 Oct 2020 20:06:25 -0400 (EDT) From: James Simmons To: Andreas Dilger , Oleg Drokin , NeilBrown Date: Mon, 5 Oct 2020 20:06:15 -0400 Message-Id: <1601942781-24950-37-git-send-email-jsimmons@infradead.org> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1601942781-24950-1-git-send-email-jsimmons@infradead.org> References: <1601942781-24950-1-git-send-email-jsimmons@infradead.org> Subject: [lustre-devel] [PATCH 36/42] lustre: don't take spinlock to read a 'long'. X-BeenThere: lustre-devel@lists.lustre.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: "For discussing Lustre software development." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Lustre Development List MIME-Version: 1.0 Errors-To: lustre-devel-bounces@lists.lustre.org Sender: "lustre-devel" From: Mr NeilBrown Reading a 'long' (or unsigned long) is always an atomic operation. There is never a need to take a spinlock to just read a single 'long'. There are several procfs/debugfs/sysfs handlers which needlessly take a spinlock for this purpose. This patch: - removes the taking of the spinlock - changes the printf to scnprintf() as appropriate - directly returns the value returned by scnprintf rather than storing it in a variable - accesses the 'long' as an arg to the scnprintf(), rather than introducing a variabe to hold it. WC-bug-id: https://jira.whamcloud.com/browse/LU-6142 Lustre-commit: 023a9e4cde5498 ("LU-6142 lustre: don't take spinlock to read a 'long'.") Signed-off-by: Mr NeilBrown Reviewed-on: https://review.whamcloud.com/39743 Reviewed-by: Andreas Dilger Reviewed-by: Arshad Hussain Reviewed-by: James Simmons Signed-off-by: James Simmons --- fs/lustre/llite/lproc_llite.c | 24 ++++++------------------ fs/lustre/mdc/lproc_mdc.c | 7 +------ fs/lustre/osc/lproc_osc.c | 23 ++++++++--------------- 3 files changed, 15 insertions(+), 39 deletions(-) diff --git a/fs/lustre/llite/lproc_llite.c b/fs/lustre/llite/lproc_llite.c index 54db7eb..9b1c392 100644 --- a/fs/lustre/llite/lproc_llite.c +++ b/fs/lustre/llite/lproc_llite.c @@ -326,13 +326,9 @@ static ssize_t max_read_ahead_mb_show(struct kobject *kobj, { struct ll_sb_info *sbi = container_of(kobj, struct ll_sb_info, ll_kset.kobj); - unsigned long ra_max_mb; - spin_lock(&sbi->ll_lock); - ra_max_mb = PAGES_TO_MiB(sbi->ll_ra_info.ra_max_pages); - spin_unlock(&sbi->ll_lock); - - return scnprintf(buf, PAGE_SIZE, "%lu\n", ra_max_mb); + return scnprintf(buf, PAGE_SIZE, "%lu\n", + PAGES_TO_MiB(sbi->ll_ra_info.ra_max_pages)); } static ssize_t max_read_ahead_mb_store(struct kobject *kobj, @@ -374,13 +370,9 @@ static ssize_t max_read_ahead_per_file_mb_show(struct kobject *kobj, { struct ll_sb_info *sbi = container_of(kobj, struct ll_sb_info, ll_kset.kobj); - unsigned long ra_max_file_mb; - spin_lock(&sbi->ll_lock); - ra_max_file_mb = PAGES_TO_MiB(sbi->ll_ra_info.ra_max_pages_per_file); - spin_unlock(&sbi->ll_lock); - - return scnprintf(buf, PAGE_SIZE, "%lu\n", ra_max_file_mb); + return scnprintf(buf, PAGE_SIZE, "%lu\n", + PAGES_TO_MiB(sbi->ll_ra_info.ra_max_pages_per_file)); } static ssize_t max_read_ahead_per_file_mb_store(struct kobject *kobj, @@ -419,13 +411,9 @@ static ssize_t max_read_ahead_whole_mb_show(struct kobject *kobj, { struct ll_sb_info *sbi = container_of(kobj, struct ll_sb_info, ll_kset.kobj); - unsigned long ra_max_whole_mb; - - spin_lock(&sbi->ll_lock); - ra_max_whole_mb = PAGES_TO_MiB(sbi->ll_ra_info.ra_max_read_ahead_whole_pages); - spin_unlock(&sbi->ll_lock); - return scnprintf(buf, PAGE_SIZE, "%lu\n", ra_max_whole_mb); + return scnprintf(buf, PAGE_SIZE, "%lu\n", + PAGES_TO_MiB(sbi->ll_ra_info.ra_max_read_ahead_whole_pages)); } static ssize_t max_read_ahead_whole_mb_store(struct kobject *kobj, diff --git a/fs/lustre/mdc/lproc_mdc.c b/fs/lustre/mdc/lproc_mdc.c index d7506ea..662be42 100644 --- a/fs/lustre/mdc/lproc_mdc.c +++ b/fs/lustre/mdc/lproc_mdc.c @@ -44,13 +44,8 @@ static int mdc_max_dirty_mb_seq_show(struct seq_file *m, void *v) { struct obd_device *obd = m->private; struct client_obd *cli = &obd->u.cli; - unsigned long val; - spin_lock(&cli->cl_loi_list_lock); - val = PAGES_TO_MiB(cli->cl_dirty_max_pages); - spin_unlock(&cli->cl_loi_list_lock); - - seq_printf(m, "%lu\n", val); + seq_printf(m, "%lu\n", PAGES_TO_MiB(cli->cl_dirty_max_pages)); return 0; } diff --git a/fs/lustre/osc/lproc_osc.c b/fs/lustre/osc/lproc_osc.c index 14cbe54..7ea9530 100644 --- a/fs/lustre/osc/lproc_osc.c +++ b/fs/lustre/osc/lproc_osc.c @@ -87,7 +87,7 @@ static ssize_t max_rpcs_in_flight_show(struct kobject *kobj, obd_kset.kobj); struct client_obd *cli = &obd->u.cli; - return sprintf(buf, "%u\n", cli->cl_max_rpcs_in_flight); + return scnprintf(buf, PAGE_SIZE, "%u\n", cli->cl_max_rpcs_in_flight); } static ssize_t max_rpcs_in_flight_store(struct kobject *kobj, @@ -139,13 +139,9 @@ static ssize_t max_dirty_mb_show(struct kobject *kobj, struct obd_device *obd = container_of(kobj, struct obd_device, obd_kset.kobj); struct client_obd *cli = &obd->u.cli; - unsigned long val; - spin_lock(&cli->cl_loi_list_lock); - val = PAGES_TO_MiB(cli->cl_dirty_max_pages); - spin_unlock(&cli->cl_loi_list_lock); - - return scnprintf(buf, PAGE_SIZE, "%lu\n", val); + return scnprintf(buf, PAGE_SIZE, "%lu\n", + PAGES_TO_MiB(cli->cl_dirty_max_pages)); } static ssize_t max_dirty_mb_store(struct kobject *kobj, @@ -252,7 +248,8 @@ static ssize_t cur_dirty_bytes_show(struct kobject *kobj, obd_kset.kobj); struct client_obd *cli = &obd->u.cli; - return sprintf(buf, "%lu\n", cli->cl_dirty_pages << PAGE_SHIFT); + return scnprintf(buf, PAGE_SIZE, "%lu\n", + cli->cl_dirty_pages << PAGE_SHIFT); } LUSTRE_RO_ATTR(cur_dirty_bytes); @@ -264,7 +261,7 @@ static ssize_t cur_grant_bytes_show(struct kobject *kobj, obd_kset.kobj); struct client_obd *cli = &obd->u.cli; - return sprintf(buf, "%lu\n", cli->cl_avail_grant); + return scnprintf(buf, PAGE_SIZE, "%lu\n", cli->cl_avail_grant); } static ssize_t cur_grant_bytes_store(struct kobject *kobj, @@ -284,12 +281,8 @@ static ssize_t cur_grant_bytes_store(struct kobject *kobj, return rc; /* this is only for shrinking grant */ - spin_lock(&cli->cl_loi_list_lock); - if (val >= cli->cl_avail_grant) { - spin_unlock(&cli->cl_loi_list_lock); + if (val >= cli->cl_avail_grant) return -EINVAL; - } - spin_unlock(&cli->cl_loi_list_lock); with_imp_locked(obd, imp, rc) if (imp->imp_state == LUSTRE_IMP_FULL) @@ -307,7 +300,7 @@ static ssize_t cur_lost_grant_bytes_show(struct kobject *kobj, obd_kset.kobj); struct client_obd *cli = &obd->u.cli; - return sprintf(buf, "%lu\n", cli->cl_lost_grant); + return scnprintf(buf, PAGE_SIZE, "%lu\n", cli->cl_lost_grant); } LUSTRE_RO_ATTR(cur_lost_grant_bytes);