From patchwork Tue Nov 17 11:52:27 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Layton X-Patchwork-Id: 7635981 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 C06089F65E for ; Tue, 17 Nov 2015 11:53:32 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id C2CD3204E2 for ; Tue, 17 Nov 2015 11:53:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C220F204EC for ; Tue, 17 Nov 2015 11:53:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753413AbbKQLx0 (ORCPT ); Tue, 17 Nov 2015 06:53:26 -0500 Received: from mail-qk0-f176.google.com ([209.85.220.176]:32992 "EHLO mail-qk0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753297AbbKQLxX (ORCPT ); Tue, 17 Nov 2015 06:53:23 -0500 Received: by qkas77 with SMTP id s77so1711470qka.0 for ; Tue, 17 Nov 2015 03:53:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=poochiereds_net.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=j4Ynp8cQOjekg3IqMLGhZOCUFl9QzOj1KOFYpyrZAgk=; b=y3i+fa5DFHj2NIZZHWGvXbQ1pQJb3xoaxunqKvyS0WITvEnJaqviz3Bq1HFp4JXFuj z27jYiX4VF7t87Jga+9Ym5hyKWkn57RMERizPqNPKr/iNbiHoF9AhMdpmSESfnN3tcHo b/+JUuhLeZIpksxkhlKBtdM2hNlGRFFKUvR0dGO+uzlFhM6bOJZgWXgaYudU/faK6T2/ 7cFt6j5pW8JAPyMz5Gme0uTREyyQ81D09bVdDKQyS5LKMCk4q5fq52yoq18YognB+bkS 29z1TvqxWzC6GKvSjWQGblgTs0cEya6Q0hx3FrNP3kg/e6ZSc3EV9r3rfBxC/j/O6GWa FBSw== 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=j4Ynp8cQOjekg3IqMLGhZOCUFl9QzOj1KOFYpyrZAgk=; b=m1uwOPAVNshHpV47xLpxUZEmfzxE9BXJwtVKVYv4b80pEifH/3tCD+MGRgRmnkS6Ns FvTqmTarBIjBjBo7C8M+WvgfXz80L7FkHpo8fdcT4450LBx2DGGa4HsMcvJRTEaFBdNV sFN4OUKyRPBRzeBLHM1UlrlTD6IH82rga+0NcEYLoWJ+iS/hd3Wv2Ur1tHI3ElNmc0Le eTDUhEf8Ygvy1E9msLodv4940q8vsVD8HAbrwlceIopQwTb8PbMRFqwV9Wb9PtehGpL0 82QLOPQcmMdFn/EMfNiYYGZ1PMpTeWH7YAIRmal30yg5E3teei93eTKa+S4EOp5cY11H DAiA== X-Gm-Message-State: ALoCoQlDTKW5Orh8+rPbOEjmgVeDnJ0dvDKSa+JZ+GyjAYIqiwhY10K3fvYfsxXpa7qk+btRx7qj X-Received: by 10.55.74.7 with SMTP id x7mr41571728qka.71.1447761202718; Tue, 17 Nov 2015 03:53:22 -0800 (PST) Received: from tlielax.poochiereds.net ([2606:a000:1125:4075::d5a]) by smtp.googlemail.com with ESMTPSA id w10sm1583910qhc.16.2015.11.17.03.53.21 (version=TLSv1/SSLv3 cipher=OTHER); Tue, 17 Nov 2015 03:53:22 -0800 (PST) From: Jeff Layton X-Google-Original-From: Jeff Layton To: bfields@fieldses.org, trond.myklebust@primarydata.com Cc: linux-nfs@vger.kernel.org, Eric Paris , Alexander Viro , linux-fsdevel@vger.kernel.org Subject: [PATCH v1 05/38] fs: add fput_global Date: Tue, 17 Nov 2015 06:52:27 -0500 Message-Id: <1447761180-4250-6-git-send-email-jeff.layton@primarydata.com> X-Mailer: git-send-email 2.4.3 In-Reply-To: <1447761180-4250-1-git-send-email-jeff.layton@primarydata.com> References: <1447761180-4250-1-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=-7.4 required=5.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,RP_MATCHES_RCVD,T_DKIM_INVALID,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 global delayed_fput infrastructure that kthreads use. fput_global will queue to the global_fput list if the last reference was put. The caller can then use fput_global_flush to force the final __fput to run. While we're at it, export fput_global_flush as nfsd will need to use that as well. Cc: Al Viro Signed-off-by: Jeff Layton --- fs/file_table.c | 33 +++++++++++++++++++++++++++++++++ include/linux/file.h | 1 + 2 files changed, 34 insertions(+) diff --git a/fs/file_table.c b/fs/file_table.c index 0bf8ddc680ab..d214c45765e6 100644 --- a/fs/file_table.c +++ b/fs/file_table.c @@ -262,6 +262,7 @@ void fput_global_flush(void) { flush_delayed_work(&global_fput_work); } +EXPORT_SYMBOL(fput_global_flush); /** * fput - put a struct file reference @@ -304,6 +305,38 @@ void fput(struct file *file) } EXPORT_SYMBOL(fput); +/** + * fput_global - 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 global_fput infrastructure that + * kthreads use. The userland process can use fput_global() on one or more + * struct files and then call fput_global_flush() to ensure that they are + * completely closed before proceeding. + * + * The main user is nfsd, which uses this to ensure that all cached but + * otherwise unused files are closed to allow a userland request for a lease + * to proceed. + * + * Returns true if the final fput was done, false otherwise. The caller can + * use this to determine whether to fput_global_flush afterward. + */ +bool fput_global(struct file *file) +{ + if (atomic_long_dec_and_test(&file->f_count)) { + if (llist_add(&file->f_u.fu_llist, &global_fput_list)) + schedule_delayed_work(&global_fput_work, 1); + return true; + } + return false; +} +EXPORT_SYMBOL(fput_global); + /* * synchronous analog of fput(); for kernel threads that might be needed * in some umount() (and thus can't use fput_global_flush() without diff --git a/include/linux/file.h b/include/linux/file.h index 73bb7cee57e9..7803aed00271 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_global(struct file *); struct file_operations; struct vfsmount;