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b=izzpAktnPo21SYzIh9hXTXe0RZ6g/ANmkLvnZlsUybS/xII5F1NSNyziIFciBiGUwW c7911ocPJdzlrIvam8lvNZ18sLpZrI+7M2He6IWeOGQ0rk4D1DZLVpfMYx8WRtJj3PTw WUO6WoeG75+AnAf3sgGv1GUPb59Kgkfc9L/aRuF9LRloHgQjn5k8b5R5N2kjaMwKaM+Y RzZrzNZ3puTc+LC2sAWnYMe0RINpStqP43pabP2iStfbqaQW/+Jl8EB7SfIl/etPLjnh 3Oxhmu2fIz0EYUAOOl4Xi/U6geeGHhm8/D5hDKujEafN1mg6kqms8o3SOmzxDDRdaUBB o8ww== X-Gm-Message-State: AOAM53176KPvbXA2iKm0btRK5nCJfVEMW3x/bA1VoPqEZoUUs2HGYCyW f/xymVLahH2IRB5ny1m7I1rblx8kzvigHmVUDaPhJA== X-Google-Smtp-Source: ABdhPJypQ8GemOXeRAlB5nBwa/LaXTEzwLO62LM4I6+2OuCpeLVCa5nLj+566PgoZJjKJzgw0+xwotjje7pT9PlLG2A= X-Received: by 2002:aa7:dd05:: with SMTP id i5mr6011841edv.300.1615424006716; Wed, 10 Mar 2021 16:53:26 -0800 (PST) MIME-Version: 1.0 References: <20210226002030.653855-1-ruansy.fnst@fujitsu.com> <20210310130227.GN3479805@casper.infradead.org> <20210310142159.kudk7q2ogp4yqn36@fiona> <20210310142643.GQ3479805@casper.infradead.org> In-Reply-To: <20210310142643.GQ3479805@casper.infradead.org> From: Dan Williams Date: Wed, 10 Mar 2021 16:53:15 -0800 Message-ID: To: Matthew Wilcox X-PDR: PASS X-Source-IP: 209.85.208.42 X-ServerName: mail-ed1-f42.google.com X-Proofpoint-SPF-Result: pass X-Proofpoint-SPF-Record: v=spf1 include:_spf.intel.com include:_spf.google.com -all X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=9919 signatures=668683 X-Proofpoint-Spam-Details: rule=tap_notspam policy=tap score=0 priorityscore=0 lowpriorityscore=0 mlxlogscore=638 bulkscore=0 phishscore=0 spamscore=0 suspectscore=0 adultscore=0 clxscore=170 impostorscore=0 mlxscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2103110003 X-Spam: Clean Cc: Jan Kara , linux-nvdimm , "Darrick J. Wong" , david , Linux Kernel Mailing List , Shiyang Ruan , linux-xfs , ocfs2-devel@oss.oracle.com, Al Viro , Neal Gompa , linux-fsdevel , Btrfs BTRFS Subject: Re: [Ocfs2-devel] [PATCH v2 00/10] fsdax, xfs: Add reflink&dedupe support for fsdax X-BeenThere: ocfs2-devel@oss.oracle.com X-Mailman-Version: 2.1.9 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: ocfs2-devel-bounces@oss.oracle.com Errors-To: ocfs2-devel-bounces@oss.oracle.com X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=9919 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 suspectscore=0 adultscore=0 phishscore=0 malwarescore=0 mlxscore=0 bulkscore=0 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2103110003 X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=9919 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxscore=0 bulkscore=0 mlxlogscore=999 adultscore=0 impostorscore=0 suspectscore=0 clxscore=1011 malwarescore=0 priorityscore=1501 phishscore=0 spamscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2103110003 On Wed, Mar 10, 2021 at 6:27 AM Matthew Wilcox wrote: > > On Wed, Mar 10, 2021 at 08:21:59AM -0600, Goldwyn Rodrigues wrote: > > On 13:02 10/03, Matthew Wilcox wrote: > > > On Wed, Mar 10, 2021 at 07:30:41AM -0500, Neal Gompa wrote: > > > > Forgive my ignorance, but is there a reason why this isn't wired up to > > > > Btrfs at the same time? It seems weird to me that adding a feature > > > > > > btrfs doesn't support DAX. only ext2, ext4, XFS and FUSE have DAX support. > > > > > > If you think about it, btrfs and DAX are diametrically opposite things. > > > DAX is about giving raw access to the hardware. btrfs is about offering > > > extra value (RAID, checksums, ...), none of which can be done if the > > > filesystem isn't in the read/write path. > > > > > > That's why there's no DAX support in btrfs. If you want DAX, you have > > > to give up all the features you like in btrfs. So you may as well use > > > a different filesystem. > > > > DAX on btrfs has been attempted[1]. Of course, we could not > > But why? A completeness fetish? I don't understand why you decided > to do this work. Isn't DAX useful for pagecache minimization on read even if it is awkward for a copy-on-write fs? Seems it would be a useful case to have COW'd VM images on BTRFS that don't need superfluous page cache allocations. _______________________________________________ Ocfs2-devel mailing list Ocfs2-devel@oss.oracle.com https://oss.oracle.com/mailman/listinfo/ocfs2-devel