From patchwork Sun Jun 13 23:11:27 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Simmons X-Patchwork-Id: 12317961 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=-16.8 required=3.0 tests=BAYES_00, 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 E7BCDC48BE8 for ; Sun, 13 Jun 2021 23:12:44 +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 AA1EB611CA for ; Sun, 13 Jun 2021 23:12:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AA1EB611CA Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass 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 D187B21F6CC; Sun, 13 Jun 2021 16:12:18 -0700 (PDT) Received: from smtp4.ccs.ornl.gov (smtp4.ccs.ornl.gov [160.91.203.40]) by pdx1-mailman02.dreamhost.com (Postfix) with ESMTP id 60EAD21F157 for ; Sun, 13 Jun 2021 16:11:45 -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 D36BD100B059; Sun, 13 Jun 2021 19:11:38 -0400 (EDT) Received: by star.ccs.ornl.gov (Postfix, from userid 2004) id D20DA9C306; Sun, 13 Jun 2021 19:11:38 -0400 (EDT) From: James Simmons To: Andreas Dilger , Oleg Drokin , NeilBrown Date: Sun, 13 Jun 2021 19:11:27 -0400 Message-Id: <1623625897-17706-18-git-send-email-jsimmons@infradead.org> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1623625897-17706-1-git-send-email-jsimmons@infradead.org> References: <1623625897-17706-1-git-send-email-jsimmons@infradead.org> Subject: [lustre-devel] [PATCH 17/27] lustre: mdc: start changelog thread upon first access 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: Alex Zhuravlev thus leaving the caller a chance to set CHANGELOG_FLAG_FOLLOW, otherwise the thread (started from open()) can reach the end of the changelog and exit early. WC-bug-id: https://jira.whamcloud.com/browse/LU-14663 Lustre-commit: 72a08ea547dceb54 ("LU-14663 mdc: start changelog thread upon first access") Signed-off-by: Alex Zhuravlev Reviewed-on: https://review.whamcloud.com/43513 Reviewed-by: Andreas Dilger Reviewed-by: Alexander Boyko Reviewed-by: John L. Hammond Reviewed-by: Oleg Drokin Signed-off-by: James Simmons --- fs/lustre/mdc/mdc_changelog.c | 54 +++++++++++++++++++++++++++++-------------- 1 file changed, 37 insertions(+), 17 deletions(-) diff --git a/fs/lustre/mdc/mdc_changelog.c b/fs/lustre/mdc/mdc_changelog.c index 31c6c8a..d366720 100644 --- a/fs/lustre/mdc/mdc_changelog.c +++ b/fs/lustre/mdc/mdc_changelog.c @@ -363,6 +363,33 @@ static int chlg_load(void *args) return rc; } +static int chlg_start_thread(struct file *file) +{ + struct chlg_reader_state *crs = file->private_data; + struct task_struct *task; + int rc = 0; + + if (likely(crs->crs_prod_task)) + return 0; + if (unlikely(file->f_mode & FMODE_READ) == 0) + return 0; + + mutex_lock(&crs->crs_lock); + if (!crs->crs_prod_task) { + task = kthread_run(chlg_load, crs, "chlg_load_thread"); + if (IS_ERR(task)) { + rc = PTR_ERR(task); + CERROR("%s: cannot start changelog thread: rc = %d\n", + crs->crs_ced->ced_name, rc); + goto out; + } + crs->crs_prod_task = task; + } +out: + mutex_unlock(&crs->crs_lock); + return rc; +} + /** * Read handler, dequeues records from the chlg_reader_state if any. * No partial records are copied to userland so this function can return less @@ -396,6 +423,10 @@ static ssize_t chlg_read(struct file *file, char __user *buff, size_t count, return -EAGAIN; } + rc = chlg_start_thread(file); + if (rc) + return rc; + rc = wait_event_interruptible(crs->crs_waitq_cons, crs->crs_rec_count > 0 || crs->crs_eof || crs->crs_err); @@ -601,8 +632,6 @@ static int chlg_open(struct inode *inode, struct file *file) { struct chlg_reader_state *crs; struct chlg_registered_dev *dev; - struct task_struct *task; - int rc; dev = container_of(inode->i_cdev, struct chlg_registered_dev, ced_cdev); @@ -620,24 +649,10 @@ static int chlg_open(struct inode *inode, struct file *file) init_waitqueue_head(&crs->crs_waitq_prod); init_waitqueue_head(&crs->crs_waitq_cons); - if (file->f_mode & FMODE_READ) { - task = kthread_run(chlg_load, crs, "chlg_load_thread"); - if (IS_ERR(task)) { - rc = PTR_ERR(task); - CERROR("%s: cannot start changelog thread: rc = %d\n", - dev->ced_name, rc); - goto err_crs; - } - crs->crs_prod_task = task; - } + crs->crs_prod_task = NULL; file->private_data = crs; return 0; - -err_crs: - kref_put(&dev->ced_refs, chlg_dev_clear); - kfree(crs); - return rc; } /** @@ -679,6 +694,11 @@ static unsigned int chlg_poll(struct file *file, poll_table *wait) { struct chlg_reader_state *crs = file->private_data; unsigned int mask = 0; + int rc; + + rc = chlg_start_thread(file); + if (rc) + return rc; mutex_lock(&crs->crs_lock); poll_wait(file, &crs->crs_waitq_cons, wait);