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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED, USER_AGENT_MUTT 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 D9A54C282DA for ; Wed, 17 Apr 2019 16:47:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A2FEE20835 for ; Wed, 17 Apr 2019 16:47:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="jdu7R5tm" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732590AbfDQQrZ (ORCPT ); Wed, 17 Apr 2019 12:47:25 -0400 Received: from userp2120.oracle.com ([156.151.31.85]:49140 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729395AbfDQQrY (ORCPT ); Wed, 17 Apr 2019 12:47:24 -0400 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x3HGd84P062934; Wed, 17 Apr 2019 16:47:03 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2018-07-02; bh=dAzZzlzW4BqSVsUKnl3rcAJNjKkzS9NrXYNg0NNxDfE=; b=jdu7R5tmOy8WIA7xbveD2+UI3FsXsef2uP9SS6iw1hVLAMuMVaD7IEv+kN0hYBNk5lGM HxVgTe8bOjNg9Ytmpt3pxuuPhPizF597x3j1VsvmTITk5X/VMPxuRfrQ+ztdowY68kvo EUjIzmV/ALQoD+VazTDesjc4ZW9Y/QwybjAew1vTzUkKE75DgA5QkrQXEjPQ+zrqIaH+ vzhJtHesyH06AgzjRe/S37ZPD8sm2LuFJ0H1lLkqphpAoVfLXrKD+xtXrESwHWUph8QC uCVZ25oaPcKSS/1Umu/KvdgmRjSS6VRYGwETS/u3pYfQrLqznjkde+ZV0a52fQoHqiTk Kw== Received: from userp3020.oracle.com (userp3020.oracle.com [156.151.31.79]) by userp2120.oracle.com with ESMTP id 2rusnf24w7-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 17 Apr 2019 16:47:03 +0000 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x3HGkR3f167890; Wed, 17 Apr 2019 16:47:02 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by userp3020.oracle.com with ESMTP id 2rubq721e0-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 17 Apr 2019 16:47:02 +0000 Received: from abhmp0019.oracle.com (abhmp0019.oracle.com [141.146.116.25]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id x3HGl07i016790; Wed, 17 Apr 2019 16:47:01 GMT Received: from localhost (/10.159.130.58) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 17 Apr 2019 09:47:00 -0700 Date: Wed, 17 Apr 2019 09:46:59 -0700 From: "Darrick J. Wong" To: Goldwyn Rodrigues Cc: linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, jack@suse.cz, david@fromorbit.com, willy@infradead.org, hch@lst.de, kilobyte@angband.pl, dsterba@suse.cz, nborisov@suse.com, linux-nvdimm@lists.01.org, Goldwyn Rodrigues Subject: Re: [PATCH 04/18] dax: Introduce IOMAP_DAX_COW to CoW edges during writes Message-ID: <20190417164659.GD4740@magnolia> References: <20190416164154.30390-1-rgoldwyn@suse.de> <20190416164154.30390-5-rgoldwyn@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190416164154.30390-5-rgoldwyn@suse.de> User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9230 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1904170112 X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9230 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1904170112 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue, Apr 16, 2019 at 11:41:40AM -0500, Goldwyn Rodrigues wrote: > From: Goldwyn Rodrigues > > The IOMAP_DAX_COW is a iomap type which performs copy of > edges of data while performing a write if start/end are > not page aligned. The source address is expected in > iomap->inline_data. > > dax_copy_edges() is a helper functions performs a copy from > one part of the device to another for data not page aligned. > If iomap->inline_data is NULL, it memset's the area to zero. > > Signed-off-by: Goldwyn Rodrigues > --- > fs/dax.c | 41 ++++++++++++++++++++++++++++++++++++++++- > include/linux/iomap.h | 1 + > 2 files changed, 41 insertions(+), 1 deletion(-) > > diff --git a/fs/dax.c b/fs/dax.c > index ca0671d55aa6..4b4ac51fbd16 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > @@ -1083,6 +1083,40 @@ int __dax_zero_page_range(struct block_device *bdev, > } > EXPORT_SYMBOL_GPL(__dax_zero_page_range); > > +/* > + * dax_copy_edges - Copies the part of the pages not included in > + * the write, but required for CoW because > + * offset/offset+length are not page aligned. > + */ > +static void dax_copy_edges(struct inode *inode, loff_t pos, loff_t length, > + struct iomap *iomap, void *daddr) > +{ > + unsigned offset = pos & (PAGE_SIZE - 1); > + loff_t end = pos + length; > + loff_t pg_end = round_up(end, PAGE_SIZE); > + void *saddr = iomap->inline_data; > + /* > + * Copy the first part of the page > + * Note: we pass offset as length > + */ > + if (offset) { > + if (saddr) > + memcpy(daddr, saddr, offset); I've been wondering, do we need memcpy_mcsafe here? > + else > + memset(daddr, 0, offset); Or here? (Or any of the other places we call memcpy/memset in this series...) Because I think we'd prefer to return EIO on bad pmem over a machine check. --D > + } > + > + /* Copy the last part of the range */ > + if (end < pg_end) { > + if (saddr) > + memcpy(daddr + offset + length, > + saddr + offset + length, pg_end - end); > + else > + memset(daddr + offset + length, 0, > + pg_end - end); > + } > +} > + > static loff_t > dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data, > struct iomap *iomap) > @@ -1104,9 +1138,11 @@ dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data, > return iov_iter_zero(min(length, end - pos), iter); > } > > - if (WARN_ON_ONCE(iomap->type != IOMAP_MAPPED)) > + if (WARN_ON_ONCE(iomap->type != IOMAP_MAPPED > + && iomap->type != IOMAP_DAX_COW)) Usually the '&&' goes on the first line, right? > return -EIO; > > + > /* > * Write can allocate block for an area which has a hole page mapped > * into page tables. We have to tear down these mappings so that data > @@ -1143,6 +1179,9 @@ dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data, > break; > } > > + if (iomap->type == IOMAP_DAX_COW) > + dax_copy_edges(inode, pos, length, iomap, kaddr); No return value? So the pmem copy never fails? --D > + > map_len = PFN_PHYS(map_len); > kaddr += offset; > map_len -= offset; > diff --git a/include/linux/iomap.h b/include/linux/iomap.h > index 0fefb5455bda..6e885c5a38a3 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_DAX_COW 0x06 /* Copy data pointed by inline_data before write*/ > > /* > * Flags for all iomap mappings: > -- > 2.16.4 >