From patchwork Mon Aug 16 19:48:40 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 12439175 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=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 8A65BC4320A for ; Mon, 16 Aug 2021 19:51:55 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 3BCE560F38 for ; Mon, 16 Aug 2021 19:51:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 3BCE560F38 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id D2A1A8D000E; Mon, 16 Aug 2021 15:51:54 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id CDAA48D0001; Mon, 16 Aug 2021 15:51:54 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BA2B58D000E; Mon, 16 Aug 2021 15:51:54 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0152.hostedemail.com [216.40.44.152]) by kanga.kvack.org (Postfix) with ESMTP id 9B5848D0001 for ; Mon, 16 Aug 2021 15:51:54 -0400 (EDT) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 4BF6520BE4 for ; Mon, 16 Aug 2021 19:51:54 +0000 (UTC) X-FDA: 78481989348.14.9C8807F Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by imf21.hostedemail.com (Postfix) with ESMTP id B0A6AD025BBF for ; Mon, 16 Aug 2021 19:51:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1629143513; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=HXTa/VyECSSTBgPq2TU+rmvN898vFz2Xyhub0w4Arrg=; b=CY5Ha1Tc/PnKP+kYP1pnIq5FsNoNivZA3XN5Ac2iUj2+hq2gbq5Jr6ylMX9JO8+mAzvcqU FHjZTBJXwljTPoQmOtb36+kzW5WYEJppN8DNtMiJEd9QyzBeRSqweTAKBssgF/EqAyTZ8f Q7Yu+gTP0fq21uIuP6o5dxL1tFBVbYo= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-101-CEYb4fPPN2aT7B97vW8omg-1; Mon, 16 Aug 2021 15:51:51 -0400 X-MC-Unique: CEYb4fPPN2aT7B97vW8omg-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 17C951082921; Mon, 16 Aug 2021 19:51:46 +0000 (UTC) Received: from t480s.redhat.com (unknown [10.39.192.85]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6FFAE5C1D5; Mon, 16 Aug 2021 19:51:26 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: David Hildenbrand , Linus Torvalds , Andrew Morton , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Alexander Viro , Alexey Dobriyan , Steven Rostedt , Peter Zijlstra , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Petr Mladek , Sergey Senozhatsky , Andy Shevchenko , Rasmus Villemoes , Kees Cook , "Eric W. Biederman" , Greg Ungerer , Geert Uytterhoeven , Mike Rapoport , Vlastimil Babka , Vincenzo Frascino , Chinwen Chang , Catalin Marinas , "Matthew Wilcox (Oracle)" , Huang Ying , Jann Horn , Feng Tang , Kevin Brodsky , Michael Ellerman , Shawn Anastasio , Steven Price , Nicholas Piggin , Christian Brauner , Jens Axboe , Gabriel Krisman Bertazi , Peter Xu , Suren Baghdasaryan , Shakeel Butt , Marco Elver , Daniel Jordan , Nicolas Viennot , Thomas Cedeno , Michal Hocko , Miklos Szeredi , Chengguang Xu , =?utf-8?q?Christian_K=C3=B6nig?= , Florian Weimer , David Laight , linux-unionfs@vger.kernel.org, linux-api@vger.kernel.org, x86@kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v2 7/7] fs: update documentation of get_write_access() and friends Date: Mon, 16 Aug 2021 21:48:40 +0200 Message-Id: <20210816194840.42769-8-david@redhat.com> In-Reply-To: <20210816194840.42769-1-david@redhat.com> References: <20210816194840.42769-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Rspamd-Queue-Id: B0A6AD025BBF Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=CY5Ha1Tc; spf=none (imf21.hostedemail.com: domain of david@redhat.com has no SPF policy when checking 216.205.24.124) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com X-Rspamd-Server: rspam01 X-Stat-Signature: q9t6os5ph4ajgcezuqkiu1rybwykg4g9 X-HE-Tag: 1629143513-25977 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: As VM_DENYWRITE does no longer exists, let's spring-clean the documentation of get_write_access() and friends. Acked-by: "Eric W. Biederman" Signed-off-by: David Hildenbrand --- include/linux/fs.h | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-) diff --git a/include/linux/fs.h b/include/linux/fs.h index 640574294216..e0dc3e96ed72 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -3055,15 +3055,20 @@ static inline void file_end_write(struct file *file) } /* + * This is used for regular files where some users -- especially the + * currently executed binary in a process, previously handled via + * VM_DENYWRITE -- cannot handle concurrent write (and maybe mmap + * read-write shared) accesses. + * * get_write_access() gets write permission for a file. * put_write_access() releases this write permission. - * This is used for regular files. - * We cannot support write (and maybe mmap read-write shared) accesses and - * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode - * can have the following values: - * 0: no writers, no VM_DENYWRITE mappings - * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist - * > 0: (i_writecount) users are writing to the file. + * deny_write_access() denies write access to a file. + * allow_write_access() re-enables write access to a file. + * + * The i_writecount field of an inode can have the following values: + * 0: no write access, no denied write access + * < 0: (-i_writecount) users that denied write access to the file. + * > 0: (i_writecount) users that have write access to the file. * * Normally we operate on that counter with atomic_{inc,dec} and it's safe * except for the cases where we don't hold i_writecount yet. Then we need to