From patchwork Thu Sep 17 12:39:46 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Layton X-Patchwork-Id: 7206411 Return-Path: X-Original-To: patchwork-linux-fsdevel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 1A2FE9F336 for ; Thu, 17 Sep 2015 12:40:39 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 400602080E for ; Thu, 17 Sep 2015 12:40:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 47B1920809 for ; Thu, 17 Sep 2015 12:40:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751979AbbIQMj7 (ORCPT ); Thu, 17 Sep 2015 08:39:59 -0400 Received: from mail-yk0-f180.google.com ([209.85.160.180]:33490 "EHLO mail-yk0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751452AbbIQMj5 (ORCPT ); Thu, 17 Sep 2015 08:39:57 -0400 Received: by ykft14 with SMTP id t14so15186685ykf.0 for ; Thu, 17 Sep 2015 05:39:56 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=kGpDKtXdMEOZjIxvX7yKlIB0uWC2Onn4SZDa4lfj7TI=; b=ZEXEO/mBmQgiVxnlEOXsTsWcLW5h1UlARwTHFXm1qrYZCrHxx6r4vfE7SgWdqYiFW7 myij068NDe1jdM2JdciK5+7n55OSa49lBnxcE99iEKaobHiGU9swhiA6c5gRF09JXckr sROSF9QXEhWJy8CT8jzguYj2f3wIa/nB50RgZ5yUbhofzrl/06Wt/yDjdSUD/Yo6pt3P FOCcNl+S2ofQhrwtAfNgGj4Cw3sPVc0ZLtbhk4euEBHL9dt0AmdrlHwkAz8WHVE2trK5 iKYugEkQ7dv8tKtoviLlW7sZSRaB1g5kOLEsAxtQGJCDljrLdOIuQi6zbzRZPDXVGzEv Whig== X-Gm-Message-State: ALoCoQk+agmcC64pOQ3By/IguOR6vVOtQrKVN09z/cpBjSCR+BksHjneGDcCsXZs98+ZMBDoQsKx X-Received: by 10.170.203.134 with SMTP id u128mr34197656yke.80.1442493596458; Thu, 17 Sep 2015 05:39:56 -0700 (PDT) Received: from tlielax.poochiereds.net ([2606:a000:1105:8e:3a60:77ff:fe93:a95d]) by smtp.googlemail.com with ESMTPSA id q128sm1878652ywf.27.2015.09.17.05.39.55 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 17 Sep 2015 05:39:55 -0700 (PDT) From: Jeff Layton X-Google-Original-From: Jeff Layton To: Al Viro Cc: bfields@fieldses.org, linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 3/4] fs: add fput_queue Date: Thu, 17 Sep 2015 08:39:46 -0400 Message-Id: <1442493587-32499-4-git-send-email-jeff.layton@primarydata.com> X-Mailer: git-send-email 2.4.3 In-Reply-To: <1442493587-32499-1-git-send-email-jeff.layton@primarydata.com> References: <1442493587-32499-1-git-send-email-jeff.layton@primarydata.com> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP When nfsd caches a file, we want to be able to close it down in advance of setlease attempts. Setting a lease is generally done at the behest of userland, so we need a mechanism to ensure that a userland task can completely close a file without having to return back to userspace. To do this, we borrow the delayed_fput infrastructure that kthreads use. fput_queue will queue to the delayed_fput list if the last reference was put. The caller can then call flush_delayed_fput to ensure that the files are completely closed before proceeding. Signed-off-by: Jeff Layton --- fs/file_table.c | 27 +++++++++++++++++++++++++++ include/linux/file.h | 1 + 2 files changed, 28 insertions(+) diff --git a/fs/file_table.c b/fs/file_table.c index 8cfeaee6323f..95361d2b8a08 100644 --- a/fs/file_table.c +++ b/fs/file_table.c @@ -302,6 +302,33 @@ void fput(struct file *file) } EXPORT_SYMBOL(fput); +/** + * fput_queue - do an fput without using task_work + * @file: file of which to put the reference + * + * When fput is called in the context of a userland process, it'll queue the + * actual work (__fput()) to be done just before returning to userland. In some + * cases however, we need to ensure that the __fput runs before that point. + * There is no safe way to flush work that has been queued via task_work_add + * however, so to do this we borrow the delayed_fput infrastructure that + * kthreads use. The userland process can use fput_queue() on one or more + * struct files and then call flush_delayed_fput() to ensure that they are + * completely closed before proceeding. + * + * Returns true if the final fput was done, false otherwise. The caller can + * use this to determine whether to flush_delayed_fput afterward. + */ +bool fput_queue(struct file *file) +{ + if (atomic_long_dec_and_test(&file->f_count)) { + if (llist_add(&file->f_u.fu_llist, &delayed_fput_list)) + schedule_delayed_work(&delayed_fput_work, 1); + return true; + } + return false; +} +EXPORT_SYMBOL(fput_queue); + /* * synchronous analog of fput(); for kernel threads that might be needed * in some umount() (and thus can't use flush_delayed_fput() without diff --git a/include/linux/file.h b/include/linux/file.h index f87d30882a24..f9308c9a0746 100644 --- a/include/linux/file.h +++ b/include/linux/file.h @@ -12,6 +12,7 @@ struct file; extern void fput(struct file *); +extern bool fput_queue(struct file *); struct file_operations; struct vfsmount;