From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-13.5 required=5.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id 3F9577DE59 for ; Fri, 14 Dec 2018 17:16:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730322AbeLNRQN (ORCPT ); Fri, 14 Dec 2018 12:16:13 -0500 Received: from mail-pg1-f196.google.com ([209.85.215.196]:40741 "EHLO mail-pg1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730315AbeLNRQM (ORCPT ); Fri, 14 Dec 2018 12:16:12 -0500 Received: by mail-pg1-f196.google.com with SMTP id z10so2974621pgp.7 for ; Fri, 14 Dec 2018 09:16:12 -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=yD7OmIaga8bq3vgrhrUeca0ttxxjagifsHLQHNzU5W8=; b=q3/CpAxD8RTwSJRxe5o3byeeJqR4Ch9hUc+/pjXFAQHyESWPfGmuc9y016j2l0B/Xi iS5TEYe/572UOGk6qTUy/EBPF5sohGdF2ZNPjZmHrmtC0RB9p4UAxKf/aEWSyQjYkJGS hiJuNCETCQGWMg6FZL37p47irAMo33zWPoArR1izOd4yzgD00jCUyzX+wnNwImOMELMX JIRZs26qd+A29xirIw3kZtAjP9sNrkRt48cnoTU9mlzvu0BN1GCQ8n+bJvxcYe9LENjh X1AM1EtQrgCaXc+FeG4GR8Bl/R+fbTGdnOAhDXmJyi6z7OK0fAzRpGYZ97xlWT3jUPrL jT4Q== 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=yD7OmIaga8bq3vgrhrUeca0ttxxjagifsHLQHNzU5W8=; b=cetFhuaZCDJmRDmDy2LzCaK2RJUUWJ3d+Wyup13Rv/hUD9Z79upWn2o1XAcGNtj5Fp Z+b9dXW/pq/s1iaIxTuDENiaSSFeJiexOISP03BDnjBtxc1CDqGPq6fSDlsRpoE42d/t h2q3+yXaplEhbeksPhpZCPe8ry8WESSqz6aSHY98OwF7mPsopbz70QO6xso1cbneNq0S riBp5wCl5Op0Aag59wr7GlYJm+761bPi2xcv452x3nSn9pfKtF1M6PDUQCOrx8NEKmiv t/rRhaSYAjVgEew+/H0sKg9KobuzS9qj3kLFyZYFsyRR7Z0RRSc9ltC4zVQaDUgbIlV7 jF3w== X-Gm-Message-State: AA+aEWZJ1Rf2vhwjNSoaP9ANDXCU9xVyWc9Y+l86/rFKeSqKd49ehqIX jhfA9x2bjgMITtrTd01rPJRz4w== X-Google-Smtp-Source: AFSGD/VXkMTwawtJFy5GzNnm00dKDRrt8F4j6Io6OBC/4OXzLeoNlmGpk0vqxx2kzPbz3iJXYDAwIw== X-Received: by 2002:a63:4c4e:: with SMTP id m14mr3433828pgl.173.1544807772132; Fri, 14 Dec 2018 09:16:12 -0800 (PST) Received: from surenb0.mtv.corp.google.com ([2620:0:1000:1612:3320:4357:47df:276b]) by smtp.googlemail.com with ESMTPSA id g185sm7605761pfc.174.2018.12.14.09.16.08 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 14 Dec 2018 09:16:09 -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 1/6] fs: kernfs: add poll file operation Date: Fri, 14 Dec 2018 09:15:03 -0800 Message-Id: <20181214171508.7791-2-surenb@google.com> X-Mailer: git-send-email 2.20.0.405.gbc1bbc6f85-goog In-Reply-To: <20181214171508.7791-1-surenb@google.com> References: <20181214171508.7791-1-surenb@google.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@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 dbf5bc250bfd..2d8b91f4475d 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); -- 2.20.0.405.gbc1bbc6f85-goog