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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0B659C433FE for ; Wed, 5 Jan 2022 18:23:22 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7077A6B0071; Wed, 5 Jan 2022 13:23:22 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 68FA56B0073; Wed, 5 Jan 2022 13:23:22 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 508BF6B0074; Wed, 5 Jan 2022 13:23:22 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0063.hostedemail.com [216.40.44.63]) by kanga.kvack.org (Postfix) with ESMTP id 3C3F46B0071 for ; Wed, 5 Jan 2022 13:23:22 -0500 (EST) Received: from smtpin15.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id EDDCB84A21 for ; Wed, 5 Jan 2022 18:23:21 +0000 (UTC) X-FDA: 78997055802.15.0CFC5FE Received: from mail-pf1-f170.google.com (mail-pf1-f170.google.com [209.85.210.170]) by imf17.hostedemail.com (Postfix) with ESMTP id 86AD04000F for ; Wed, 5 Jan 2022 18:22:58 +0000 (UTC) Received: by mail-pf1-f170.google.com with SMTP id m1so94129pfk.8 for ; Wed, 05 Jan 2022 10:23:19 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20210112.gappssmtp.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=O3txqHljQl/GCNxyCJxfFojCjkO470bmaKiTOmC1xSE=; b=iDaMKn+q7SGqX3ujdNUGLIq8rR9uST+ZG/7EUkKHkYITiY/9guw1ZRXf3Ht59Dz2kA IljULJEO3i+pPOzOnZXhD3vALfxADxcPKVZqVKrO/pzmcxvaa37+fRTER/WdpRu2YXiH XqA6bprq+O3qlgt6rpbnONeUrs2A5iUPw0Rr1Oy1rrK9MTDAm9TcPBdRKFW5yS4YufWJ Npd4V2aXugQPk341QkO2dH7kuWmID7i5orec/rVIGU1QPRTl8oafYAQgyLhqEOk1JFG/ fpy6WAxwAtIUhlSp+IGClZEoLSmXUYQNHBB+0UeoK9tpNTY6HPYa/lBmoGxCn8zwKVzT bdLw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=O3txqHljQl/GCNxyCJxfFojCjkO470bmaKiTOmC1xSE=; b=U4s7CItakIzZq+RS9Rx2V7NmRaDH84lJe5dUslraoyK1qOQU9E/i2ttx4NHoJdubST ByXo8ntBbaQzsFR7ZrdapTcC6b2FHIA/Y/3IXigossQM5OUHQ4t+rNwBZfkbxqqBj+0b /0L5FFwDRiC2hxU/Emn2q10f7hScwCXQZ9E5oZfntcwug/KUAfSXZtQQK+UAPFb1H2A+ jodRl8tFB6My3kLZiUgdJe288VQmo4mQfsCee7N5Ybs3/YrKndf6tXwcusFyGq9A+6vM Szv7jdwd7tyrml009izA+sk5pvveAcPBnhobq6xgR/k3x2U/h4g3QGkythfoPiuYB8vU ahFg== X-Gm-Message-State: AOAM531nfWXbolR0oNo+cJt/zhkZZCJLPkfa0vz6vHMl8KOk+l5P6+8H yKHG0RxiUhMs9YSthaw+Lptg4gMd9X0xUc721CY7Tw== X-Google-Smtp-Source: ABdhPJxoBP/aT1AEtcGz3BudjHksIAmWp/YqSFrZQveftZYxEW3pAAMJ+2H/kJ2DcT1CwoBX6W8azzzA4zy/f9WM0+k= X-Received: by 2002:a63:710f:: with SMTP id m15mr18291969pgc.40.1641406998932; Wed, 05 Jan 2022 10:23:18 -0800 (PST) MIME-Version: 1.0 References: <20211226143439.3985960-1-ruansy.fnst@fujitsu.com> <20211226143439.3985960-3-ruansy.fnst@fujitsu.com> <20220105181230.GC398655@magnolia> In-Reply-To: <20220105181230.GC398655@magnolia> From: Dan Williams Date: Wed, 5 Jan 2022 10:23:08 -0800 Message-ID: Subject: Re: [PATCH v9 02/10] dax: Introduce holder for dax_device To: "Darrick J. Wong" Cc: Shiyang Ruan , Linux Kernel Mailing List , linux-xfs , Linux NVDIMM , Linux MM , linux-fsdevel , david , Christoph Hellwig , Jane Chu Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 86AD04000F X-Stat-Signature: 4qci9h65cwg1f618ieri3j1ubq4jjfef Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=intel-com.20210112.gappssmtp.com header.s=20210112 header.b=iDaMKn+q; dmarc=fail reason="No valid SPF, DKIM not aligned (relaxed)" header.from=intel.com (policy=none); spf=none (imf17.hostedemail.com: domain of dan.j.williams@intel.com has no SPF policy when checking 209.85.210.170) smtp.mailfrom=dan.j.williams@intel.com X-HE-Tag: 1641406978-86471 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Jan 5, 2022 at 10:12 AM Darrick J. Wong wrote: > > On Sun, Dec 26, 2021 at 10:34:31PM +0800, Shiyang Ruan wrote: > > To easily track filesystem from a pmem device, we introduce a holder for > > dax_device structure, and also its operation. This holder is used to > > remember who is using this dax_device: > > - When it is the backend of a filesystem, the holder will be the > > instance of this filesystem. > > - When this pmem device is one of the targets in a mapped device, the > > holder will be this mapped device. In this case, the mapped device > > has its own dax_device and it will follow the first rule. So that we > > can finally track to the filesystem we needed. > > > > The holder and holder_ops will be set when filesystem is being mounted, > > or an target device is being activated. > > > > Signed-off-by: Shiyang Ruan > > --- > > drivers/dax/super.c | 62 +++++++++++++++++++++++++++++++++++++++++++++ > > include/linux/dax.h | 29 +++++++++++++++++++++ > > 2 files changed, 91 insertions(+) > > > > diff --git a/drivers/dax/super.c b/drivers/dax/super.c > > index c46f56e33d40..94c51f2ee133 100644 > > --- a/drivers/dax/super.c > > +++ b/drivers/dax/super.c > > @@ -20,15 +20,20 @@ > > * @inode: core vfs > > * @cdev: optional character interface for "device dax" > > * @private: dax driver private data > > + * @holder_data: holder of a dax_device: could be filesystem or mapped device > > * @flags: state and boolean properties > > + * @ops: operations for dax_device > > + * @holder_ops: operations for the inner holder > > */ > > struct dax_device { > > struct inode inode; > > struct cdev cdev; > > void *private; > > struct percpu_rw_semaphore rwsem; > > + void *holder_data; > > unsigned long flags; > > const struct dax_operations *ops; > > + const struct dax_holder_operations *holder_ops; > > }; > > > > static dev_t dax_devt; > > @@ -192,6 +197,29 @@ int dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff, > > } > > EXPORT_SYMBOL_GPL(dax_zero_page_range); > > > > +int dax_holder_notify_failure(struct dax_device *dax_dev, u64 off, > > + u64 len, int mf_flags) > > +{ > > + int rc; > > + > > + dax_read_lock(dax_dev); > > + if (!dax_alive(dax_dev)) { > > + rc = -ENXIO; > > + goto out; > > + } > > + > > + if (!dax_dev->holder_ops) { > > + rc = -EOPNOTSUPP; > > + goto out; > > + } > > + > > + rc = dax_dev->holder_ops->notify_failure(dax_dev, off, len, mf_flags); > > +out: > > + dax_read_unlock(dax_dev); > > + return rc; > > +} > > +EXPORT_SYMBOL_GPL(dax_holder_notify_failure); > > + > > #ifdef CONFIG_ARCH_HAS_PMEM_API > > void arch_wb_cache_pmem(void *addr, size_t size); > > void dax_flush(struct dax_device *dax_dev, void *addr, size_t size) > > @@ -254,6 +282,10 @@ void kill_dax(struct dax_device *dax_dev) > > return; > > dax_write_lock(dax_dev); > > clear_bit(DAXDEV_ALIVE, &dax_dev->flags); > > + > > + /* clear holder data */ > > + dax_dev->holder_ops = NULL; > > + dax_dev->holder_data = NULL; > > dax_write_unlock(dax_dev); > > } > > EXPORT_SYMBOL_GPL(kill_dax); > > @@ -401,6 +433,36 @@ void put_dax(struct dax_device *dax_dev) > > } > > EXPORT_SYMBOL_GPL(put_dax); > > > > +void dax_register_holder(struct dax_device *dax_dev, void *holder, > > + const struct dax_holder_operations *ops) > > +{ > > + if (!dax_alive(dax_dev)) > > + return; > > + > > + dax_dev->holder_data = holder; > > + dax_dev->holder_ops = ops; > > Shouldn't this return an error code if the dax device is dead or if > someone already registered a holder? I'm pretty sure XFS should not > bind to a dax device if someone else already registered for it... Agree, yes. > > ...unless you want to use a notifier chain for failure events so that > there can be multiple consumers of dax failure events? No, I would hope not. It should be 1:1 holders to dax-devices. Similar ownership semantics like bd_prepare_to_claim().