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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 AF449C5B578 for ; Mon, 1 Jul 2019 06:40:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9129F214AF for ; Mon, 1 Jul 2019 06:40:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727346AbfGAGkl (ORCPT ); Mon, 1 Jul 2019 02:40:41 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:7683 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725616AbfGAGkl (ORCPT ); Mon, 1 Jul 2019 02:40:41 -0400 Received: from DGGEMS410-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 94218D6CDC1276CFDC7C; Mon, 1 Jul 2019 14:40:38 +0800 (CST) Received: from [10.134.22.195] (10.134.22.195) by smtp.huawei.com (10.3.19.210) with Microsoft SMTP Server (TLS) id 14.3.439.0; Mon, 1 Jul 2019 14:40:29 +0800 Subject: Re: [PATCH RFC] iomap: introduce IOMAP_TAIL To: Gao Xiang CC: , , , , References: <20190629073020.22759-1-yuchao0@huawei.com> From: Chao Yu Message-ID: Date: Mon, 1 Jul 2019 14:40:28 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.134.22.195] X-CFilter-Loop: Reflected Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Hi Xiang, On 2019/6/29 17:34, Gao Xiang wrote: > Hi Chao, > > On 2019/6/29 15:30, Chao Yu wrote: >> Some filesystems like erofs/reiserfs have the ability to pack tail >> data into metadata, however iomap framework can only support mapping >> inline data with IOMAP_INLINE type, it restricts that: >> - inline data should be locating at page #0. >> - inline size should equal to .i_size >> So we can not use IOMAP_INLINE to handle tail-packing case. >> >> This patch introduces new mapping type IOMAP_TAIL to map tail-packed >> data for further use of erofs. >> >> Signed-off-by: Chao Yu >> --- >> fs/iomap.c | 22 ++++++++++++++++++++++ >> include/linux/iomap.h | 1 + >> 2 files changed, 23 insertions(+) >> >> diff --git a/fs/iomap.c b/fs/iomap.c >> index 12654c2e78f8..ae7777ce77d0 100644 >> --- a/fs/iomap.c >> +++ b/fs/iomap.c >> @@ -280,6 +280,23 @@ iomap_read_inline_data(struct inode *inode, struct page *page, >> SetPageUptodate(page); >> } >> >> +static void >> +iomap_read_tail_data(struct inode *inode, struct page *page, >> + struct iomap *iomap) >> +{ >> + size_t size = i_size_read(inode) & (PAGE_SIZE - 1); >> + void *addr; >> + >> + if (PageUptodate(page)) >> + return; >> + >> + addr = kmap_atomic(page); >> + memcpy(addr, iomap->inline_data, size); >> + memset(addr + size, 0, PAGE_SIZE - size); > > need flush_dcache_page(page) here for new page cache page since > it's generic iomap code (althrough not necessary for x86, arm), I am not sure... > see commit d2b2c6dd227b and c01778001a4f... Thanks for your reminding, these all codes were copied from iomap_read_inline_data(), so I think we need a separated patch to fix this issue if necessary. Thanks, > > Thanks, > Gao Xiang > >> + kunmap_atomic(addr); >> + SetPageUptodate(page); >> +} >> + >> static loff_t >> iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data, >> struct iomap *iomap) >> @@ -298,6 +315,11 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data, >> return PAGE_SIZE; >> } >> >> + if (iomap->type == IOMAP_TAIL) { >> + iomap_read_tail_data(inode, page, iomap); >> + return PAGE_SIZE; >> + } >> + >> /* zero post-eof blocks as the page may be mapped */ >> iomap_adjust_read_range(inode, iop, &pos, length, &poff, &plen); >> if (plen == 0) >> diff --git a/include/linux/iomap.h b/include/linux/iomap.h >> index 2103b94cb1bf..7e1ee48e3db7 100644 >> --- a/include/linux/iomap.h >> +++ b/include/linux/iomap.h >> @@ -25,6 +25,7 @@ struct vm_fault; >> #define IOMAP_MAPPED 0x03 /* blocks allocated at @addr */ >> #define IOMAP_UNWRITTEN 0x04 /* blocks allocated at @addr in unwritten state */ >> #define IOMAP_INLINE 0x05 /* data inline in the inode */ >> +#define IOMAP_TAIL 0x06 /* tail data packed in metdata */ >> >> /* >> * Flags for all iomap mappings: >> > . >