From patchwork Thu Feb 10 04:52:07 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dai Ngo X-Patchwork-Id: 12741275 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 62326C433EF for ; Thu, 10 Feb 2022 04:52:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233691AbiBJEwQ (ORCPT ); Wed, 9 Feb 2022 23:52:16 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:37072 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231733AbiBJEwP (ORCPT ); Wed, 9 Feb 2022 23:52:15 -0500 Received: from mx0b-00069f02.pphosted.com (mx0b-00069f02.pphosted.com [205.220.177.32]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 15AB31B3; Wed, 9 Feb 2022 20:52:17 -0800 (PST) Received: from pps.filterd (m0246632.ppops.net [127.0.0.1]) by mx0b-00069f02.pphosted.com (8.16.1.2/8.16.1.2) with SMTP id 21A4ANLZ013515; Thu, 10 Feb 2022 04:52:15 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : cc : subject : date : message-id : in-reply-to : references; s=corp-2021-07-09; bh=4tWJY0xnAJLFgMaVTnRJZ0+CnzE3fCsuRD4Dcje3u1M=; b=aw3Cv7V6K1t+X4ofP4dCCghmECfvs8N475EM1xIBb6rjLV6XfqBkR+CePQQA/0ZcyGgv 2wtFz8HwZFHQ177+yyb4tuJq6th44Nsl4HbVio0uzXo3sphjCwH3kr1ozyTGIPkbjQqw RwmIczFJAyEX/WvbEfrLH3U2VpEn0Sx4LD1QQz+uxCESmKnY8R/0WRatpDWMyNYgZBFM JLg0RVbKkom0sy9tmXKVsZmi+Wvq3Bgb1DjKfft+2qsitUCr48mDGQTvTmk3hOhRIZLK OOTLEMVQ9GSmrUQOVFEeo/XtGWpUP3Ks7YL6iGj+iJIboAoXGKa7L0MBjU339JnX0dJH bw== Received: from aserp3030.oracle.com (aserp3030.oracle.com [141.146.126.71]) by mx0b-00069f02.pphosted.com with ESMTP id 3e345srqq1-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 10 Feb 2022 04:52:14 +0000 Received: from pps.filterd (aserp3030.oracle.com [127.0.0.1]) by aserp3030.oracle.com (8.16.1.2/8.16.1.2) with SMTP id 21A4oB1x015266; Thu, 10 Feb 2022 04:52:14 GMT Received: from pps.reinject (localhost [127.0.0.1]) by aserp3030.oracle.com with ESMTP id 3e1f9jk20b-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 10 Feb 2022 04:52:14 +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 21A4qC5O020851; Thu, 10 Feb 2022 04:52:13 GMT Received: from ca-common-hq.us.oracle.com (ca-common-hq.us.oracle.com [10.211.9.209]) by aserp3030.oracle.com with ESMTP id 3e1f9jk1y6-2; Thu, 10 Feb 2022 04:52:13 +0000 From: Dai Ngo To: chuck.lever@oracle.com, bfields@fieldses.org Cc: jlayton@redhat.com, viro@zeniv.linux.org.uk, linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: [PATCH RFC v12 1/3] fs/lock: add new callback, lm_lock_conflict, to lock_manager_operations Date: Wed, 9 Feb 2022 20:52:07 -0800 Message-Id: <1644468729-30383-2-git-send-email-dai.ngo@oracle.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1644468729-30383-1-git-send-email-dai.ngo@oracle.com> References: <1644468729-30383-1-git-send-email-dai.ngo@oracle.com> X-Proofpoint-GUID: t4Tom0HTlOTz_tABCx4VNe4ZBSejETtS X-Proofpoint-ORIG-GUID: t4Tom0HTlOTz_tABCx4VNe4ZBSejETtS Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Add new callback, lm_lock_conflict, to lock_manager_operations to allow the lock manager to take appropriate action to resolve the lock conflict if possible. The callback takes 1 argument, the file_lock of the blocker and returns true if the conflict was resolved else returns false. Note that the lock manager has to be able to resolve the conflict while the spinlock flc_lock is held. Lock manager, such as NFSv4 courteous server, uses this callback to resolve conflict by destroying lock owner, or the NFSv4 courtesy client (client that has expired but allowed to maintains its states) that owns the lock. Signed-off-by: Dai Ngo --- Documentation/filesystems/locking.rst | 2 ++ fs/locks.c | 14 ++++++++++---- include/linux/fs.h | 8 ++++++++ 3 files changed, 20 insertions(+), 4 deletions(-) diff --git a/Documentation/filesystems/locking.rst b/Documentation/filesystems/locking.rst index d36fe79167b3..57ce0fbc8ab1 100644 --- a/Documentation/filesystems/locking.rst +++ b/Documentation/filesystems/locking.rst @@ -439,6 +439,7 @@ prototypes:: void (*lm_break)(struct file_lock *); /* break_lease callback */ int (*lm_change)(struct file_lock **, int); bool (*lm_breaker_owns_lease)(struct file_lock *); + bool (*lm_lock_conflict)(struct file_lock *); locking rules: @@ -450,6 +451,7 @@ lm_grant: no no no lm_break: yes no no lm_change yes no no lm_breaker_owns_lease: no no no +lm_lock_conflict: no no no ====================== ============= ================= ========= buffer_head diff --git a/fs/locks.c b/fs/locks.c index 0fca9d680978..052b42cc7f25 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -853,10 +853,13 @@ posix_test_lock(struct file *filp, struct file_lock *fl) spin_lock(&ctx->flc_lock); list_for_each_entry(cfl, &ctx->flc_posix, fl_list) { - if (posix_locks_conflict(fl, cfl)) { - locks_copy_conflock(fl, cfl); - goto out; - } + if (!posix_locks_conflict(fl, cfl)) + continue; + if (cfl->fl_lmops && cfl->fl_lmops->lm_lock_conflict && + !cfl->fl_lmops->lm_lock_conflict(cfl)) + continue; + locks_copy_conflock(fl, cfl); + goto out; } fl->fl_type = F_UNLCK; out: @@ -1059,6 +1062,9 @@ static int posix_lock_inode(struct inode *inode, struct file_lock *request, list_for_each_entry(fl, &ctx->flc_posix, fl_list) { if (!posix_locks_conflict(request, fl)) continue; + if (fl->fl_lmops && fl->fl_lmops->lm_lock_conflict && + !fl->fl_lmops->lm_lock_conflict(fl)) + continue; if (conflock) locks_copy_conflock(conflock, fl); error = -EAGAIN; diff --git a/include/linux/fs.h b/include/linux/fs.h index bbf812ce89a8..726d0005e32f 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1068,6 +1068,14 @@ struct lock_manager_operations { int (*lm_change)(struct file_lock *, int, struct list_head *); void (*lm_setup)(struct file_lock *, void **); bool (*lm_breaker_owns_lease)(struct file_lock *); + /* + * This callback function is called after a lock conflict is + * detected. This allows the lock manager of the lock that + * causes the conflict to see if the conflict can be resolved + * somehow. If it can then this callback returns false; the + * conflict was resolved, else returns true. + */ + bool (*lm_lock_conflict)(struct file_lock *cfl); }; struct lock_manager {