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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 9554EC433ED for ; Fri, 14 May 2021 15:41:31 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 53D7D6144C for ; Fri, 14 May 2021 15:41:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 53D7D6144C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id A13CB6B0036; Fri, 14 May 2021 11:41:30 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9EB2C6B006E; Fri, 14 May 2021 11:41:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 88D756B0070; Fri, 14 May 2021 11:41:30 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0028.hostedemail.com [216.40.44.28]) by kanga.kvack.org (Postfix) with ESMTP id 55BCC6B0036 for ; Fri, 14 May 2021 11:41:30 -0400 (EDT) Received: from smtpin32.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id EBB8C8249980 for ; Fri, 14 May 2021 15:41:29 +0000 (UTC) X-FDA: 78140251098.32.87C6AFC Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf23.hostedemail.com (Postfix) with ESMTP id 22CB8A000382 for ; Fri, 14 May 2021 15:41:29 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 67574B05C; Fri, 14 May 2021 15:41:28 +0000 (UTC) Subject: Re: [PATCH v10 11/33] mm: Handle per-folio private data To: "Matthew Wilcox (Oracle)" , akpm@linux-foundation.org Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Christoph Hellwig , Jeff Layton References: <20210511214735.1836149-1-willy@infradead.org> <20210511214735.1836149-12-willy@infradead.org> From: Vlastimil Babka Message-ID: <9a748624-5f07-acf2-667a-39fc271f830d@suse.cz> Date: Fri, 14 May 2021 17:41:28 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: <20210511214735.1836149-12-willy@infradead.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Authentication-Results: imf23.hostedemail.com; dkim=none; dmarc=none; spf=pass (imf23.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.15 as permitted sender) smtp.mailfrom=vbabka@suse.cz X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 22CB8A000382 X-Stat-Signature: 6gf7r1dxe1ifb5pi6md5ow1tmkiim364 X-HE-Tag: 1621006889-393853 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: On 5/11/21 11:47 PM, Matthew Wilcox (Oracle) wrote: > Add folio_get_private() which mirrors page_private() -- ie folio private > data is the same as page private data. The only difference is that these > return a void * instead of an unsigned long, which matches the majority > of users. > > Turn attach_page_private() into folio_attach_private() and reimplement > attach_page_private() as a wrapper. No filesystem which uses page private > data currently supports compound pages, so we're free to define the rules. > attach_page_private() may only be called on a head page; if you want > to add private data to a tail page, you can call set_page_private() > directly (and shouldn't increment the page refcount! That should be > done when adding private data to the head page / folio). > > This saves 597 bytes of text with the distro-derived config that I'm > testing due to removing the calls to compound_head() in get_page() > & put_page(). > > Signed-off-by: Matthew Wilcox (Oracle) > Reviewed-by: Christoph Hellwig > Acked-by: Jeff Layton Acked-by: Vlastimil Babka