From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) (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 2BB2A81756; Mon, 26 Feb 2024 12:56:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.176.79.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708952208; cv=none; b=AVmGHMpfDRNJJXKAPACV3iplJn3JK/SRAhSwo0RCkYEmWlmYb9uNATaDi16Spv0Nbgqu/vEKfrh5G+D7dbEoCsB9fZsXlIowNTvP/ZC6atIeKT7ukl224qDz4UaCla8MjUJCBOhFgxICB4Bhy3HWRt4aJTCvnZoQz1cMUeicXQA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708952208; c=relaxed/simple; bh=NC9zbuoZghbczDmZXWcpM9NU9mKbcnjtKFhuyF8fuZs=; h=Date:From:To:CC:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=XmlU2Y5svXNQP2I1mmdauHhBrlOMRxZwf4b/qSDRV5vSTFMobtAggOGhjwUEYUO3ghjJbVg6k519nQPU2cYQBvW7/xSLrSY9VtN4b8MH3Y+xJO1zFwl1hztsuEqHzLeZNLaHchOGYV3w7YwqTRutHB6wYfpVWhqlLZLgxs8nSGs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=Huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=185.176.79.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=Huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.18.186.31]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4Tk0s85lMRz6K9JP; Mon, 26 Feb 2024 20:53:00 +0800 (CST) Received: from lhrpeml500005.china.huawei.com (unknown [7.191.163.240]) by mail.maildlp.com (Postfix) with ESMTPS id F41F9140FB6; Mon, 26 Feb 2024 20:56:43 +0800 (CST) Received: from localhost (10.202.227.76) by lhrpeml500005.china.huawei.com (7.191.163.240) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.35; Mon, 26 Feb 2024 12:56:43 +0000 Date: Mon, 26 Feb 2024 12:56:42 +0000 From: Jonathan Cameron To: John Groves CC: John Groves , Jonathan Corbet , "Dan Williams" , Vishal Verma , Dave Jiang , "Alexander Viro" , Christian Brauner , "Jan Kara" , Matthew Wilcox , , , , , , , Dave Chinner , Christoph Hellwig , , Subject: Re: [RFC PATCH 10/20] famfs: famfs_open_device() & dax_holder_operations Message-ID: <20240226125642.000076d2@Huawei.com> In-Reply-To: <74359fdc83688fb1aac1cb2c336fbd725590a131.1708709155.git.john@groves.net> References: <74359fdc83688fb1aac1cb2c336fbd725590a131.1708709155.git.john@groves.net> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 4.1.0 (GTK 3.24.33; x86_64-w64-mingw32) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: lhrpeml100002.china.huawei.com (7.191.160.241) To lhrpeml500005.china.huawei.com (7.191.163.240) On Fri, 23 Feb 2024 11:41:54 -0600 John Groves wrote: > Famfs works on both /dev/pmem and /dev/dax devices. This commit introduces > the function that opens a block (pmem) device and the struct > dax_holder_operations that are needed for that ABI. > > In this commit, support for opening character /dev/dax is stubbed. A > later commit introduces this capability. > > Signed-off-by: John Groves Formatting comments mostly same as previous patches, so I'll stop repeating them. > --- > fs/famfs/famfs_inode.c | 83 ++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 83 insertions(+) > > diff --git a/fs/famfs/famfs_inode.c b/fs/famfs/famfs_inode.c > index 3329aff000d1..82c861998093 100644 > --- a/fs/famfs/famfs_inode.c > +++ b/fs/famfs/famfs_inode.c > @@ -68,5 +68,88 @@ static const struct super_operations famfs_ops = { > .show_options = famfs_show_options, > }; > > +/*************************************************************************************** > + * dax_holder_operations for block dax > + */ > + > +static int > +famfs_blk_dax_notify_failure( > + struct dax_device *dax_devp, > + u64 offset, > + u64 len, > + int mf_flags) > +{ > + > + pr_err("%s: dax_devp %llx offset %llx len %lld mf_flags %x\n", > + __func__, (u64)dax_devp, (u64)offset, (u64)len, mf_flags); > + return -EOPNOTSUPP; > +} > + > +const struct dax_holder_operations famfs_blk_dax_holder_ops = { > + .notify_failure = famfs_blk_dax_notify_failure, > +}; > + > +static int > +famfs_open_char_device( > + struct super_block *sb, > + struct fs_context *fc) > +{ > + pr_err("%s: Root device is %s, but your kernel does not support famfs on /dev/dax\n", > + __func__, fc->source); > + return -ENODEV; > +} > + > +/** > + * famfs_open_device() > + * > + * Open the memory device. If it looks like /dev/dax, call famfs_open_char_device(). > + * Otherwise try to open it as a block/pmem device. > + */ > +static int > +famfs_open_device( > + struct super_block *sb, > + struct fs_context *fc) > +{ > + struct famfs_fs_info *fsi = sb->s_fs_info; > + struct dax_device *dax_devp; > + u64 start_off = 0; > + struct bdev_handle *handlep; Definitely don't force alignment in local parameter definitions. Always goes wrong and makes for unreadable mess in patches! > + > + if (fsi->dax_devp) { > + pr_err("%s: already mounted\n", __func__); Fine to fail but worth a error message? Not sure on convention on this but seems noisy and maybe in userspace control which isn't good. > + return -EALREADY; > + } > + > + if (strstr(fc->source, "/dev/dax")) /* There is probably a better way to check this */ > + return famfs_open_char_device(sb, fc); > + > + if (!strstr(fc->source, "/dev/pmem")) { /* There is probably a better way to check this */ > + pr_err("%s: primary backing dev (%s) is not pmem\n", > + __func__, fc->source); > + return -EINVAL; > + } > + > + handlep = bdev_open_by_path(fc->source, FAMFS_BLKDEV_MODE, fsi, &fs_holder_ops); > + if (IS_ERR(handlep->bdev)) { > + pr_err("%s: failed blkdev_get_by_path(%s)\n", __func__, fc->source); > + return PTR_ERR(handlep->bdev); > + } > + > + dax_devp = fs_dax_get_by_bdev(handlep->bdev, &start_off, > + fsi /* holder */, > + &famfs_blk_dax_holder_ops); > + if (IS_ERR(dax_devp)) { > + pr_err("%s: unable to get daxdev from handlep->bdev\n", __func__); > + bdev_release(handlep); > + return -ENODEV; > + } > + fsi->bdev_handle = handlep; > + fsi->dax_devp = dax_devp; > + > + pr_notice("%s: root device is block dax (%s)\n", __func__, fc->source); pr_debug() Kernel log is too noisy anyway! + I'd assume we can tell this succeeded in lots of other ways. > + return 0; > +} > + > + > > MODULE_LICENSE("GPL");