From patchwork Thu Sep 27 18:17:35 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Omar Sandoval X-Patchwork-Id: 10618397 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 12C5D3CF1 for ; Thu, 27 Sep 2018 18:18:19 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0736929988 for ; Thu, 27 Sep 2018 18:18:19 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id F015F2B9EC; Thu, 27 Sep 2018 18:18:18 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 66E2D2B3B0 for ; Thu, 27 Sep 2018 18:18:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728451AbeI1Aho (ORCPT ); Thu, 27 Sep 2018 20:37:44 -0400 Received: from mail-pf1-f193.google.com ([209.85.210.193]:38021 "EHLO mail-pf1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728251AbeI1Ahn (ORCPT ); Thu, 27 Sep 2018 20:37:43 -0400 Received: by mail-pf1-f193.google.com with SMTP id x17-v6so2480339pfh.5 for ; Thu, 27 Sep 2018 11:18:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=osandov-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=pB4cjWu7kIoSAPGh3rcF+ODQvk/IUq3VExz60hmyk9c=; b=iRcBmGe2iOyXaPiMWvLgRrEGh+QqWaFC0SXLrEChkiiVJ2SYONu+OGRC9CE2krWwm3 SFI+iDm5JXO7ytk0cdjfABEIMDy4mI4MTxaA69jfNYSsB83ZyQ1jIvXND3F7q7RG+lrF FT/c+TBQ0UBukd+v6rq+Cpz0Ctk0PaGJEOmeI6AtgqIrWwxkGwz0dgsPZV22iOjlul1z Zb8c29ozRtkdq5QqVDEqqNkX4XIAH+C1W1ixwQLbtQoNyH66nGEv5361zSw0K+P6bllZ aJ3M7TvnyIikAt9c8IJFgc6zPwFIC1Lmv/8GmxjzaFEhb5lbBG/qD+LpKztjcj1rwqd0 RnYg== 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=pB4cjWu7kIoSAPGh3rcF+ODQvk/IUq3VExz60hmyk9c=; b=PmpBpnUwCECTyjpcCxH/w1gGutGx+Jp/ajyVtOkApQ+x92YyYwAX9nUUjxQsh6P3zd oHrr6QSjbJ+25NIS7fFUeBMqvOUNDadZpo+foSS8EBmMID18Kwn1+5kkwlpyOj9WTDtm +5zST0yWrQeax+Lafq4a3+N08IvQTfAEb/RGj+2VcUSv4iZ7eklFrw/w+YOQHxM8Ibk6 nvelY+7JMlGj2M/jNOuvbiwZ4UXiwzn8tsZSHy6a1s2SsItXhm09Pxevfr0e6hXUpxVX TE6kzrlmPXv3Bm8246XKhan4IhPk7g3WMY3hqOraJS5lkIRr5nWNUQp3GOONVUj3o5tI PslQ== X-Gm-Message-State: ABuFfoiheMUyvEAMolSHGdgyGd11NnbPG2DvyxXRjA6Ik8w2weSb2sWL 9NcKqVb5DQlwyoGu012Rc7pg5g== X-Google-Smtp-Source: ACcGV612aO4ToB/YjCcbARk3DH6sdoMScF3+ZHfByjDMyiZZ7dFcziLBbwS1aG3/zLbIXllhaGMD1Q== X-Received: by 2002:a17:902:1681:: with SMTP id h1-v6mr12185624plh.262.1538072291599; Thu, 27 Sep 2018 11:18:11 -0700 (PDT) Received: from vader.thefacebook.com ([2620:10d:c090:200::5:3e64]) by smtp.gmail.com with ESMTPSA id p19-v6sm4086614pgh.60.2018.09.27.11.18.09 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 27 Sep 2018 11:18:11 -0700 (PDT) From: Omar Sandoval To: linux-btrfs@vger.kernel.org Cc: kernel-team@fb.com, David Sterba , linux-fsdevel@vger.kernel.org, Jonathan Corbet , Al Viro Subject: [PATCH v9 3/6] vfs: update swap_{,de}activate documentation Date: Thu, 27 Sep 2018 11:17:35 -0700 Message-Id: <79f71cb15a9008c000ae3eb77118d32cb88948ba.1538072009.git.osandov@fb.com> X-Mailer: git-send-email 2.19.0 In-Reply-To: References: MIME-Version: 1.0 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Omar Sandoval The documentation for these functions is wrong in several ways: - swap_activate() is called with the inode locked - swap_activate() takes a swap_info_struct * and a sector_t * - swap_activate() can also return a positive number of extents it added itself - swap_deactivate() does not return anything Cc: Jonathan Corbet Cc: Al Viro Reviewed-by: Nikolay Borisov Signed-off-by: Omar Sandoval --- Hi, Jon, Al, could I get an ack on this patch? Thanks! Documentation/filesystems/Locking | 17 +++++++---------- Documentation/filesystems/vfs.txt | 12 ++++++++---- 2 files changed, 15 insertions(+), 14 deletions(-) diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking index efea228ccd8a..b970c8c2ee22 100644 --- a/Documentation/filesystems/Locking +++ b/Documentation/filesystems/Locking @@ -210,8 +210,9 @@ prototypes: int (*launder_page)(struct page *); int (*is_partially_uptodate)(struct page *, unsigned long, unsigned long); int (*error_remove_page)(struct address_space *, struct page *); - int (*swap_activate)(struct file *); - int (*swap_deactivate)(struct file *); + int (*swap_activate)(struct swap_info_struct *, struct file *, + sector_t *); + void (*swap_deactivate)(struct file *); locking rules: All except set_page_dirty and freepage may block @@ -235,8 +236,8 @@ putback_page: yes launder_page: yes is_partially_uptodate: yes error_remove_page: yes -swap_activate: no -swap_deactivate: no +swap_activate: yes +swap_deactivate: no ->write_begin(), ->write_end() and ->readpage() may be called from the request handler (/dev/loop). @@ -333,14 +334,10 @@ cleaned, or an error value if not. Note that in order to prevent the page getting mapped back in and redirtied, it needs to be kept locked across the entire operation. - ->swap_activate will be called with a non-zero argument on -files backing (non block device backed) swapfiles. A return value -of zero indicates success, in which case this file can be used for -backing swapspace. The swapspace operations will be proxied to the -address space operations. + ->swap_activate is called from sys_swapon() with the inode locked. ->swap_deactivate() will be called in the sys_swapoff() -path after ->swap_activate() returned success. +path after ->swap_activate() returned success. The inode is not locked. ----------------------- file_lock_operations ------------------------------ prototypes: diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt index a6c6a8af48a2..6e14db053eaa 100644 --- a/Documentation/filesystems/vfs.txt +++ b/Documentation/filesystems/vfs.txt @@ -652,8 +652,9 @@ struct address_space_operations { unsigned long); void (*is_dirty_writeback) (struct page *, bool *, bool *); int (*error_remove_page) (struct mapping *mapping, struct page *page); - int (*swap_activate)(struct file *); - int (*swap_deactivate)(struct file *); + int (*swap_activate)(struct swap_info_struct *, struct file *, + sector_t *); + void (*swap_deactivate)(struct file *); }; writepage: called by the VM to write a dirty page to backing store. @@ -830,8 +831,11 @@ struct address_space_operations { swap_activate: Called when swapon is used on a file to allocate space if necessary and pin the block lookup information in - memory. A return value of zero indicates success, - in which case this file can be used to back swapspace. + memory. If this returns zero, the swap system will call the address + space operations ->readpage() and ->direct_IO(). Alternatively, this + may call add_swap_extent() and return the number of extents added, in + which case the swap system will use the provided blocks directly + instead of going through the filesystem. swap_deactivate: Called during swapoff on files where swap_activate was successful.