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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 77991C3A5A1 for ; Wed, 28 Aug 2019 17:58:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 593B1206BB for ; Wed, 28 Aug 2019 17:58:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726605AbfH1R6u (ORCPT ); Wed, 28 Aug 2019 13:58:50 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36014 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726515AbfH1R6t (ORCPT ); Wed, 28 Aug 2019 13:58:49 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 280B9107DD00; Wed, 28 Aug 2019 17:58:49 +0000 (UTC) Received: from horse.redhat.com (unknown [10.18.25.158]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6668E5D9E2; Wed, 28 Aug 2019 17:58:44 +0000 (UTC) Received: by horse.redhat.com (Postfix, from userid 10451) id EB41B2206F5; Wed, 28 Aug 2019 13:58:43 -0400 (EDT) Date: Wed, 28 Aug 2019 13:58:43 -0400 From: Vivek Goyal To: Christoph Hellwig Cc: miklos@szeredi.hu, linux-nvdimm@lists.01.org, linux-kernel@vger.kernel.org, dgilbert@redhat.com, virtio-fs@redhat.com, stefanha@redhat.com, linux-fsdevel@vger.kernel.org, Dan Williams Subject: Re: [PATCH 01/19] dax: remove block device dependencies Message-ID: <20190828175843.GB912@redhat.com> References: <20190821175720.25901-1-vgoyal@redhat.com> <20190821175720.25901-2-vgoyal@redhat.com> <20190826115152.GA21051@infradead.org> <20190827163828.GA6859@redhat.com> <20190828065809.GA27426@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190828065809.GA27426@infradead.org> User-Agent: Mutt/1.12.0 (2019-05-25) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.64]); Wed, 28 Aug 2019 17:58:49 +0000 (UTC) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue, Aug 27, 2019 at 11:58:09PM -0700, Christoph Hellwig wrote: > On Tue, Aug 27, 2019 at 12:38:28PM -0400, Vivek Goyal wrote: > > > For bdev_dax_pgoff > > > I'd much rather have the partition offset if there is on in the daxdev > > > somehow so that we can get rid of the block device entirely. > > > > IIUC, there is one block_device per partition while there is only one > > dax_device for the whole disk. So we can't directly move bdev logical > > offset into dax_device. > > Well, then we need to find a way to get partitions for dax devices, > as we really should not expect a block device hiding behind a dax > dev. That is just a weird legacy assumption - block device need to > layer on top of the dax device optionally. > > > > > We probably could put this in "iomap" and leave it to filesystems to > > report offset into dax_dev in iomap that way dax generic code does not > > have to deal with it. But that probably will be a bigger change. > > And where would the file system get that information from? File system knows about block device, can it just call get_start_sect() while filling iomap->addr. And this means we don't have to have parition information in dax device. Will something like following work? (Just a proof of concept patch). --- drivers/dax/super.c | 11 +++++++++++ fs/dax.c | 6 +++--- fs/ext4/inode.c | 6 +++++- include/linux/dax.h | 1 + 4 files changed, 20 insertions(+), 4 deletions(-) Index: rhvgoyal-linux/fs/ext4/inode.c =================================================================== --- rhvgoyal-linux.orig/fs/ext4/inode.c 2019-08-28 13:51:16.051937204 -0400 +++ rhvgoyal-linux/fs/ext4/inode.c 2019-08-28 13:51:44.453937204 -0400 @@ -3589,7 +3589,11 @@ retry: WARN_ON_ONCE(1); return -EIO; } - iomap->addr = (u64)map.m_pblk << blkbits; + if (IS_DAX(inode)) + iomap->addr = ((u64)map.m_pblk << blkbits) + + (get_start_sect(iomap->bdev) * 512); + else + iomap->addr = (u64)map.m_pblk << blkbits; } if (map.m_flags & EXT4_MAP_NEW) Index: rhvgoyal-linux/fs/dax.c =================================================================== --- rhvgoyal-linux.orig/fs/dax.c 2019-08-28 13:51:16.051937204 -0400 +++ rhvgoyal-linux/fs/dax.c 2019-08-28 13:51:44.457937204 -0400 @@ -688,7 +688,7 @@ static int copy_user_dax(struct block_de long rc; int id; - rc = bdev_dax_pgoff(bdev, sector, size, &pgoff); + rc = dax_pgoff(sector, size, &pgoff); if (rc) return rc; @@ -995,7 +995,7 @@ static int dax_iomap_pfn(struct iomap *i int id, rc; long length; - rc = bdev_dax_pgoff(iomap->bdev, sector, size, &pgoff); + rc = dax_pgoff(sector, size, &pgoff); if (rc) return rc; id = dax_read_lock(); @@ -1137,7 +1137,7 @@ dax_iomap_actor(struct inode *inode, lof break; } - ret = bdev_dax_pgoff(bdev, sector, size, &pgoff); + ret = dax_pgoff(sector, size, &pgoff); if (ret) break; Index: rhvgoyal-linux/drivers/dax/super.c =================================================================== --- rhvgoyal-linux.orig/drivers/dax/super.c 2019-08-28 13:51:51.802937204 -0400 +++ rhvgoyal-linux/drivers/dax/super.c 2019-08-28 13:51:56.905937204 -0400 @@ -43,6 +43,17 @@ EXPORT_SYMBOL_GPL(dax_read_unlock); #ifdef CONFIG_BLOCK #include +int dax_pgoff(sector_t sector, size_t size, pgoff_t *pgoff) +{ + phys_addr_t phys_off = sector * 512; + + if (pgoff) + *pgoff = PHYS_PFN(phys_off); + if (phys_off % PAGE_SIZE || size % PAGE_SIZE) + return -EINVAL; + return 0; +} + int bdev_dax_pgoff(struct block_device *bdev, sector_t sector, size_t size, pgoff_t *pgoff) { Index: rhvgoyal-linux/include/linux/dax.h =================================================================== --- rhvgoyal-linux.orig/include/linux/dax.h 2019-08-28 13:51:51.802937204 -0400 +++ rhvgoyal-linux/include/linux/dax.h 2019-08-28 13:51:56.908937204 -0400 @@ -111,6 +111,7 @@ static inline bool daxdev_mapping_suppor struct writeback_control; int bdev_dax_pgoff(struct block_device *, sector_t, size_t, pgoff_t *pgoff); +int dax_pgoff(sector_t, size_t, pgoff_t *pgoff); #if IS_ENABLED(CONFIG_FS_DAX) bool __bdev_dax_supported(struct block_device *bdev, int blocksize); static inline bool bdev_dax_supported(struct block_device *bdev, int blocksize)