From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT, USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5AF4AC282C3 for ; Thu, 24 Jan 2019 21:15:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2B25D218D2 for ; Thu, 24 Jan 2019 21:15:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="gygzfM8D" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727918AbfAXVPp (ORCPT ); Thu, 24 Jan 2019 16:15:45 -0500 Received: from mail-pf1-f196.google.com ([209.85.210.196]:42075 "EHLO mail-pf1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727743AbfAXVPo (ORCPT ); Thu, 24 Jan 2019 16:15:44 -0500 Received: by mail-pf1-f196.google.com with SMTP id 64so3619509pfr.9 for ; Thu, 24 Jan 2019 13:15:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=ucF1EwcLVxCtpPOBrQuqUFcO6ME+3ZXcCq84fU7zCQU=; b=gygzfM8DMwdV2iIuQLyTUNZoqz3zBV3YtlUapmjclo6FC0Cojxkyvg4NivMng9lbsQ UWdyeeLEfhPEp8uDGJi7V+xJ1r8fLv7cSF3AgCBMzvurwt/n6qyU4ar7Cg9qTtZeIxbU J6YSkeKSSK0UPNMIulk/GIHII8GRmfVYhpB65NdU5mVAAkC5EC5Z9ITK8S75A88PP/rM YCmvpjQontE64hJ0camuKp/QHj5ID+XU4FRhNKvHB2zo3jpM7bZb6q/XuMvwwy6vaDwK BPTQ0nG+MGuEYAZ0eOa1zCAzJnqN3qOecuomYBNuInO5ONQIFkVFx7A78idtIZ3d2iHh EAXA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=ucF1EwcLVxCtpPOBrQuqUFcO6ME+3ZXcCq84fU7zCQU=; b=MH4uIc0aUUe/Wh7lqyrLEmwwXQ7QGZBuaWOk+X9O5SiuIFL+AzO+cxnFa5Uu/QDwGP sUvu8pk+NdOoPgbCEVsgrSQaXamfzUexC4W7GvVcNUFWXcCPXMTOa2WqEa7UstxpFYAT kUbD1m0+qoI3NpOYdhhdQztFI4imYLKaD0+x/TfRhn0ubMlgX2TjtEk2Shq1zrGWS1E6 YAYVfxuvVysVpheFA7+n9hgo8xQ797oUztg/oodDIZ/p/mVuGwAM+6m3eFiOXgU+xqAw vQEbWhMU8pC4MOJKBvUNj4/mG1CUXEeLaT68kmdspqrQlIvunTgYy9GWS9MdTqQJUfaM fXUQ== X-Gm-Message-State: AJcUukfRotNESMas4IUIvtvWqdLyHH0N1AWUOQyJZdJr8eIQEW9akyJa e3rCk+9NTAnYTPmeP72L8IR/TA== X-Google-Smtp-Source: ALg8bN7SzOSe/SY78Pfzr1GOzAhXFURTr4LVGcJJzkPSCrKgxlqMkTFLV98NujEgXfWObOrL6iJgLg== X-Received: by 2002:a63:31cc:: with SMTP id x195mr7538081pgx.52.1548364543402; Thu, 24 Jan 2019 13:15:43 -0800 (PST) Received: from surenb0.mtv.corp.google.com ([2620:0:1000:1612:3320:4357:47df:276b]) by smtp.googlemail.com with ESMTPSA id j197sm29626418pgc.76.2019.01.24.13.15.42 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 24 Jan 2019 13:15:42 -0800 (PST) From: Suren Baghdasaryan To: gregkh@linuxfoundation.org Cc: tj@kernel.org, lizefan@huawei.com, hannes@cmpxchg.org, axboe@kernel.dk, dennis@kernel.org, dennisszhou@gmail.com, mingo@redhat.com, peterz@infradead.org, akpm@linux-foundation.org, corbet@lwn.net, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@android.com, Suren Baghdasaryan Subject: [PATCH v3 1/5] fs: kernfs: add poll file operation Date: Thu, 24 Jan 2019 13:15:14 -0800 Message-Id: <20190124211518.244221-2-surenb@google.com> X-Mailer: git-send-email 2.20.1.321.g9e740568ce-goog In-Reply-To: <20190124211518.244221-1-surenb@google.com> References: <20190124211518.244221-1-surenb@google.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Johannes Weiner Kernfs has a standardized poll/notification mechanism for waking all pollers on all fds when a filesystem node changes. To allow polling for custom events, add a .poll callback that can override the default. This is in preparation for pollable cgroup pressure files which have per-fd trigger configurations. Signed-off-by: Johannes Weiner Signed-off-by: Suren Baghdasaryan --- fs/kernfs/file.c | 31 ++++++++++++++++++++----------- include/linux/kernfs.h | 6 ++++++ 2 files changed, 26 insertions(+), 11 deletions(-) diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c index f8d5021a652e..ae948aaa4c53 100644 --- a/fs/kernfs/file.c +++ b/fs/kernfs/file.c @@ -832,26 +832,35 @@ void kernfs_drain_open_files(struct kernfs_node *kn) * to see if it supports poll (Neither 'poll' nor 'select' return * an appropriate error code). When in doubt, set a suitable timeout value. */ +__poll_t kernfs_generic_poll(struct kernfs_open_file *of, poll_table *wait) +{ + struct kernfs_node *kn = kernfs_dentry_node(of->file->f_path.dentry); + struct kernfs_open_node *on = kn->attr.open; + + poll_wait(of->file, &on->poll, wait); + + if (of->event != atomic_read(&on->event)) + return DEFAULT_POLLMASK|EPOLLERR|EPOLLPRI; + + return DEFAULT_POLLMASK; +} + static __poll_t kernfs_fop_poll(struct file *filp, poll_table *wait) { struct kernfs_open_file *of = kernfs_of(filp); struct kernfs_node *kn = kernfs_dentry_node(filp->f_path.dentry); - struct kernfs_open_node *on = kn->attr.open; + __poll_t ret; if (!kernfs_get_active(kn)) - goto trigger; + return DEFAULT_POLLMASK|EPOLLERR|EPOLLPRI; - poll_wait(filp, &on->poll, wait); + if (kn->attr.ops->poll) + ret = kn->attr.ops->poll(of, wait); + else + ret = kernfs_generic_poll(of, wait); kernfs_put_active(kn); - - if (of->event != atomic_read(&on->event)) - goto trigger; - - return DEFAULT_POLLMASK; - - trigger: - return DEFAULT_POLLMASK|EPOLLERR|EPOLLPRI; + return ret; } static void kernfs_notify_workfn(struct work_struct *work) diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h index 5b36b1287a5a..0cac1207bb00 100644 --- a/include/linux/kernfs.h +++ b/include/linux/kernfs.h @@ -25,6 +25,7 @@ struct seq_file; struct vm_area_struct; struct super_block; struct file_system_type; +struct poll_table_struct; struct kernfs_open_node; struct kernfs_iattrs; @@ -261,6 +262,9 @@ struct kernfs_ops { ssize_t (*write)(struct kernfs_open_file *of, char *buf, size_t bytes, loff_t off); + __poll_t (*poll)(struct kernfs_open_file *of, + struct poll_table_struct *pt); + int (*mmap)(struct kernfs_open_file *of, struct vm_area_struct *vma); #ifdef CONFIG_DEBUG_LOCK_ALLOC @@ -350,6 +354,8 @@ int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name, int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent, const char *new_name, const void *new_ns); int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr); +__poll_t kernfs_generic_poll(struct kernfs_open_file *of, + struct poll_table_struct *pt); void kernfs_notify(struct kernfs_node *kn); const void *kernfs_super_ns(struct super_block *sb); -- 2.20.1.321.g9e740568ce-goog