From patchwork Mon Oct 5 11:02:26 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Layton X-Patchwork-Id: 7326291 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 9FCA09F6E4 for ; Mon, 5 Oct 2015 11:03:00 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id B27B9207C2 for ; Mon, 5 Oct 2015 11:02:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C5E2C207BC for ; Mon, 5 Oct 2015 11:02:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751627AbbJELC4 (ORCPT ); Mon, 5 Oct 2015 07:02:56 -0400 Received: from mail-qg0-f53.google.com ([209.85.192.53]:36139 "EHLO mail-qg0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751438AbbJELCx (ORCPT ); Mon, 5 Oct 2015 07:02:53 -0400 Received: by qgx61 with SMTP id 61so145872621qgx.3 for ; Mon, 05 Oct 2015 04:02:52 -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=OTauCTIgievNLZ1OCIuIpzSCzsjlN6Ln96jhAS/7BoPz8DVcsOsKLpNG17g2Zmj3ZT 18Lx4y0QWGCZEK5eOkVnYsWscUQ5T7YI+hUH0zqnMqK4vUPDMFdjXTVbd1HcCeRBCvsC 025NsqU7/GZ50L+OHRxc+J6P0M5BB0ehLcdQ+8O23KZY6KYiRvk3M8FHBGho0bGnvPPF g61dct6jM8OC+Gv2AL+ZgrDU6d7CY5R2nCvEiIZPXqh3ukeGQH2H+84Q8U/D4EdM4wMo BcHMraC6CegywlmD8MOyqT6Yd+W34PD3hJpIjRmVGeQhOCz8Nor57A2KQ9uQlinqjxgG j0JA== X-Gm-Message-State: ALoCoQkEYKaBfAqKYQsqEuycwLrjSKReflMmmvEcnpm6Ncu2wO6XwkU2V4Y8y0+M+m/Nzs5sUl4R X-Received: by 10.140.133.196 with SMTP id 187mr41041196qhf.2.1444042972567; Mon, 05 Oct 2015 04:02:52 -0700 (PDT) Received: from tlielax.poochiereds.net ([2606:a000:1125:6079::d5a]) by smtp.googlemail.com with ESMTPSA id p39sm4977719qkp.47.2015.10.05.04.02.51 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 05 Oct 2015 04:02:51 -0700 (PDT) From: Jeff Layton X-Google-Original-From: Jeff Layton To: bfields@fieldses.org Cc: linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, Al Viro Subject: [PATCH v5 04/20] fs: add fput_queue Date: Mon, 5 Oct 2015 07:02:26 -0400 Message-Id: <1444042962-6947-5-git-send-email-jeff.layton@primarydata.com> X-Mailer: git-send-email 2.4.3 In-Reply-To: <1444042962-6947-1-git-send-email-jeff.layton@primarydata.com> References: <1444042962-6947-1-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=ham 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;