From patchwork Tue Oct 20 17:33:38 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Layton X-Patchwork-Id: 7449321 Return-Path: X-Original-To: patchwork-linux-fsdevel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id A29F7BF90C for ; Tue, 20 Oct 2015 17:34:30 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id B85132083B for ; Tue, 20 Oct 2015 17:34:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C666F2083C for ; Tue, 20 Oct 2015 17:34:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753113AbbJTReU (ORCPT ); Tue, 20 Oct 2015 13:34:20 -0400 Received: from mail-qk0-f176.google.com ([209.85.220.176]:35463 "EHLO mail-qk0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753015AbbJTReD (ORCPT ); Tue, 20 Oct 2015 13:34:03 -0400 Received: by qkbl190 with SMTP id l190so10887577qkb.2 for ; Tue, 20 Oct 2015 10:34:02 -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=j4Ynp8cQOjekg3IqMLGhZOCUFl9QzOj1KOFYpyrZAgk=; b=fVQpwaRylitp4tBxvif9dyRDxN/vfuY7+pjICOoJFIoSH6EUs3hgBc0pcnbT0mMcQF WN+FOAMSL2FLu5wxnw6wtGRLm7foBy+RjGsRzBopFEavt84DdVe9t57HnRb2IDKr7tyV yLcOfnFtD9HfTOWXknuSZyoKmYa93mVBfc6+unTvspG+eaz8A3ovX6t08G96xMM2nk2k oFUQedmNz5DhTSETuQ556/ru3BJmx2XcyS0H5oKWa6SdTQyU2WajTvECTaKypo5qeOn1 FAAv8KlpVrxS7qoOCk2YfslL5emPdk6+GYLphrPUYoZMZSPBxBCQZGB7H1LpUhdQ+Pun Wt+A== X-Gm-Message-State: ALoCoQmXqXL9GTaHosg4Faan0C6cnFRWE8I242Y4KJsbfGiCsesSsVqc8RArckRM/1WUILoWmt6N X-Received: by 10.55.203.132 with SMTP id u4mr5481418qkl.71.1445362442736; Tue, 20 Oct 2015 10:34:02 -0700 (PDT) Received: from tlielax.poochiereds.net ([2606:a000:1125:6079::d5a]) by smtp.googlemail.com with ESMTPSA id m26sm1640925qki.28.2015.10.20.10.34.01 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 20 Oct 2015 10:34:02 -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 v6 05/19] fs: add fput_global Date: Tue, 20 Oct 2015 13:33:38 -0400 Message-Id: <1445362432-18869-6-git-send-email-jeff.layton@primarydata.com> X-Mailer: git-send-email 2.4.3 In-Reply-To: <1445362432-18869-1-git-send-email-jeff.layton@primarydata.com> References: <1445362432-18869-1-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, 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 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;