From patchwork Sun Feb 6 19:04:28 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dai Ngo X-Patchwork-Id: 12736690 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 9F28CC433F5 for ; Sun, 6 Feb 2022 20:02:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242621AbiBFUCR (ORCPT ); Sun, 6 Feb 2022 15:02:17 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50870 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231982AbiBFUCQ (ORCPT ); Sun, 6 Feb 2022 15:02:16 -0500 X-Greylist: delayed 3450 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Sun, 06 Feb 2022 12:02:15 PST Received: from mx0a-00069f02.pphosted.com (mx0a-00069f02.pphosted.com [205.220.165.32]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 89E17C06173B; Sun, 6 Feb 2022 12:02:15 -0800 (PST) Received: from pps.filterd (m0246629.ppops.net [127.0.0.1]) by mx0b-00069f02.pphosted.com (8.16.1.2/8.16.1.2) with SMTP id 216GWa3E026188; Sun, 6 Feb 2022 19:04:42 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=C71XcyOPptutJXLxA/mViZOuewbxZescZsclb7TwOIvhE3ujT9o9x9v/ubUOigYiPw4k 9DUFaoyD5BJI26ygxA6577IlsruMBFTqAXeMSCoP0DNd2NeoANYtWZokqoHeZVkpKbr3 94i5h31Dn1I1JZCcZGDztAPtufHcbSkkxa+xWAlvSbNm8lSvGatB4XYfhxpQrL2Zh1EB Ed5fPFVk27ETg2dgoZZz4tBg263WZu7IVE+JNN6P5FxOOLJAciYeHdrXzc16DWjz1z0L EX0T0Ngm5151MQKWS0Z93gO7KaNjBl57Ce6SfrGqj5t9lSr8Sl41EOB33Ta1+9XBjbYG bA== Received: from aserp3030.oracle.com (aserp3030.oracle.com [141.146.126.71]) by mx0b-00069f02.pphosted.com with ESMTP id 3e1h4b3nqy-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sun, 06 Feb 2022 19:04:41 +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 216J1vk3035726; Sun, 6 Feb 2022 19:04:40 GMT Received: from pps.reinject (localhost [127.0.0.1]) by aserp3030.oracle.com with ESMTP id 3e1f9ceduq-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sun, 06 Feb 2022 19:04:40 +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 216J4dFT044049; Sun, 6 Feb 2022 19:04:40 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 3e1f9cedtx-2; Sun, 06 Feb 2022 19:04:40 +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 1/3] fs/lock: add new callback, lm_lock_conflict, to lock_manager_operations Date: Sun, 6 Feb 2022 11:04:28 -0800 Message-Id: <1644174270-20681-2-git-send-email-dai.ngo@oracle.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1644174270-20681-1-git-send-email-dai.ngo@oracle.com> References: <1644174270-20681-1-git-send-email-dai.ngo@oracle.com> X-Proofpoint-GUID: 1kj4dpKw1suPRVgRctJFllDtamoJnsat X-Proofpoint-ORIG-GUID: 1kj4dpKw1suPRVgRctJFllDtamoJnsat 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 {