From patchwork Mon Aug 23 12:35:08 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 12452713 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6BF913FC8 for ; Mon, 23 Aug 2021 12:37:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=5C7whyWIKeHw98K7S+Dkt3BPS2eO5NS8RnNmkSn5luY=; b=T8y+XflmiyL+1t1HU/mAGh83W5 LDSRNYJvsbli+/WTIDvmSK/Zz/SQyu4ldfylCSQprkefW+HqVJhWGuzFKLoC2BO/R70t7TRJjd3qg qdvi64yD2ZMP+RKhHkOW2vlhL4JCH2+KRpyWbuC6LOn/u6JYjZCvIallAAhcT5eox0e90Y2cP8CuQ 1AmnzW2lhHG1ioWc26U1Nv9R2EbIyDrodZ+K3k3aEXWRT6LXRiV/nU8q3PBKm+aON3Mjp59eDWjOK d30/8OLsVpCsY9UI9sjvx+Zl1Vj6oN6Q7pYxSGxOqCMee8vPYLIOAzlFfGRDam8eFO99yhSBjA03M znn6Nt3w==; Received: from [2001:4bb8:193:fd10:c6e8:3c08:6f8b:cbf0] (helo=localhost) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1mI9BD-009j1P-LH; Mon, 23 Aug 2021 12:36:10 +0000 From: Christoph Hellwig To: Dan Williams , Vishal Verma , Dave Jiang Cc: Mike Snitzer , Matthew Wilcox , linux-xfs@vger.kernel.org, nvdimm@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org Subject: [PATCH 1/9] fsdax: improve the FS_DAX Kconfig description and help text Date: Mon, 23 Aug 2021 14:35:08 +0200 Message-Id: <20210823123516.969486-2-hch@lst.de> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210823123516.969486-1-hch@lst.de> References: <20210823123516.969486-1-hch@lst.de> Precedence: bulk X-Mailing-List: nvdimm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Rename the main option text to clarify it is for file system access, and add a bit of text that explains how to actually switch a nvdimm to a fsdax capable state. Signed-off-by: Christoph Hellwig Signed-off-by: Christoph Hellwig --- fs/Kconfig | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) diff --git a/fs/Kconfig b/fs/Kconfig index a7749c126b8e..37e4441119cf 100644 --- a/fs/Kconfig +++ b/fs/Kconfig @@ -43,7 +43,7 @@ source "fs/f2fs/Kconfig" source "fs/zonefs/Kconfig" config FS_DAX - bool "Direct Access (DAX) support" + bool "File system based Direct Access (DAX) support" depends on MMU depends on !(ARM || MIPS || SPARC) select DEV_PAGEMAP_OPS if (ZONE_DEVICE && !FS_DAX_LIMITED) @@ -53,8 +53,19 @@ config FS_DAX Direct Access (DAX) can be used on memory-backed block devices. If the block device supports DAX and the filesystem supports DAX, then you can avoid using the pagecache to buffer I/Os. Turning - on this option will compile in support for DAX; you will need to - mount the filesystem using the -o dax option. + on this option will compile in support for DAX. + + For a DAX device to support file system access it needs to have + struct pages. For the nfit based NVDIMMs this can be enabled + using the ndctl utility: + + # ndctl create-namespace --force --reconfig=namespace0.0 \ + --mode=fsdax --map=mem + + For ndctl to work CONFIG_DEV_DAX needs to be enabled as well. + For most file systems DAX support needs to be manually enable + globally or per-inode using a mount option as well. See the + file system documentation for details. If you do not have a block device that is capable of using this, or if unsure, say N. Saying Y will increase the size of the kernel