From patchwork Sat Jan 28 08:36:15 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dan Williams X-Patchwork-Id: 9543055 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 34581604AA for ; Sat, 28 Jan 2017 08:40:23 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 28B5727F07 for ; Sat, 28 Jan 2017 08:40:23 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 1DC6F28249; Sat, 28 Jan 2017 08:40:23 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id AFA4F282F5 for ; Sat, 28 Jan 2017 08:40:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751245AbdA1IkW (ORCPT ); Sat, 28 Jan 2017 03:40:22 -0500 Received: from mga04.intel.com ([192.55.52.120]:17034 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750904AbdA1IkV (ORCPT ); Sat, 28 Jan 2017 03:40:21 -0500 Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga104.fm.intel.com with ESMTP; 28 Jan 2017 00:40:20 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.33,300,1477983600"; d="scan'208";a="1100030508" Received: from dwillia2-desk3.jf.intel.com (HELO dwillia2-desk3.amr.corp.intel.com) ([10.54.39.14]) by fmsmga001.fm.intel.com with ESMTP; 28 Jan 2017 00:40:20 -0800 Subject: [RFC PATCH 02/17] dax: convert dax_inode locking to srcu From: Dan Williams To: linux-nvdimm@lists.01.org Cc: snitzer@redhat.com, toshi.kani@hpe.com, mawilcox@microsoft.com, linux-block@vger.kernel.org, jmoyer@redhat.com, linux-fsdevel@vger.kernel.org, ross.zwisler@linux.intel.com, hch@lst.de Date: Sat, 28 Jan 2017 00:36:15 -0800 Message-ID: <148559257511.11180.7445606032994481709.stgit@dwillia2-desk3.amr.corp.intel.com> In-Reply-To: <148559256378.11180.8957776806175202312.stgit@dwillia2-desk3.amr.corp.intel.com> References: <148559256378.11180.8957776806175202312.stgit@dwillia2-desk3.amr.corp.intel.com> User-Agent: StGit/0.17.1-9-g687f MIME-Version: 1.0 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP In preparation for adding dax_operations that perform ->direct_access() and user copy operations relative to a dax_inode, convert the existing dax_inode locking to srcu. Some dax drivers need to sleep in their ->direct_access() methods and user copying may fault / sleep. Signed-off-by: Dan Williams --- drivers/dax/Kconfig | 1 + drivers/dax/device.c | 18 +++++++++--------- drivers/dax/super.c | 20 ++++++++++++++++---- include/linux/dax.h | 3 +++ 4 files changed, 29 insertions(+), 13 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-block" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/drivers/dax/Kconfig b/drivers/dax/Kconfig index 39bcbf4c5e40..b7053eafd88e 100644 --- a/drivers/dax/Kconfig +++ b/drivers/dax/Kconfig @@ -1,5 +1,6 @@ menuconfig DAX tristate "DAX: direct access to differentiated memory" + select SRCU default m if NVDIMM_DAX if DAX diff --git a/drivers/dax/device.c b/drivers/dax/device.c index 5b5572314929..af06d0bfd6ea 100644 --- a/drivers/dax/device.c +++ b/drivers/dax/device.c @@ -333,16 +333,16 @@ static int __dax_dev_fault(struct dax_dev *dax_dev, struct vm_area_struct *vma, static int dax_dev_fault(struct vm_area_struct *vma, struct vm_fault *vmf) { - int rc; + int rc, id; struct file *filp = vma->vm_file; struct dax_dev *dax_dev = filp->private_data; dev_dbg(&dax_dev->dev, "%s: %s: %s (%#lx - %#lx)\n", __func__, current->comm, (vmf->flags & FAULT_FLAG_WRITE) ? "write" : "read", vma->vm_start, vma->vm_end); - rcu_read_lock(); + id = dax_read_lock(); rc = __dax_dev_fault(dax_dev, vma, vmf); - rcu_read_unlock(); + dax_read_unlock(id); return rc; } @@ -390,7 +390,7 @@ static int __dax_dev_pmd_fault(struct dax_dev *dax_dev, static int dax_dev_pmd_fault(struct vm_area_struct *vma, unsigned long addr, pmd_t *pmd, unsigned int flags) { - int rc; + int rc, id; struct file *filp = vma->vm_file; struct dax_dev *dax_dev = filp->private_data; @@ -398,9 +398,9 @@ static int dax_dev_pmd_fault(struct vm_area_struct *vma, unsigned long addr, current->comm, (flags & FAULT_FLAG_WRITE) ? "write" : "read", vma->vm_start, vma->vm_end); - rcu_read_lock(); + id = dax_read_lock(); rc = __dax_dev_pmd_fault(dax_dev, vma, addr, pmd, flags); - rcu_read_unlock(); + dax_read_unlock(id); return rc; } @@ -412,8 +412,8 @@ static const struct vm_operations_struct dax_dev_vm_ops = { static int dax_mmap(struct file *filp, struct vm_area_struct *vma) { + int rc, id; struct dax_dev *dax_dev = filp->private_data; - int rc; dev_dbg(&dax_dev->dev, "%s\n", __func__); @@ -421,9 +421,9 @@ static int dax_mmap(struct file *filp, struct vm_area_struct *vma) * We lock to check dax_inode liveness and will re-check at * fault time. */ - rcu_read_lock(); + id = dax_read_lock(); rc = check_vma(dax_dev, vma, __func__); - rcu_read_unlock(); + dax_read_unlock(id); if (rc) return rc; diff --git a/drivers/dax/super.c b/drivers/dax/super.c index e6369b851619..7c4dc97d53a8 100644 --- a/drivers/dax/super.c +++ b/drivers/dax/super.c @@ -24,11 +24,24 @@ module_param(nr_dax, int, S_IRUGO); MODULE_PARM_DESC(nr_dax, "max number of dax device instances"); static dev_t dax_devt; +DEFINE_STATIC_SRCU(dax_srcu); static struct vfsmount *dax_mnt; static DEFINE_IDA(dax_minor_ida); static struct kmem_cache *dax_cache __read_mostly; static struct super_block *dax_superblock __read_mostly; +int dax_read_lock(void) +{ + return srcu_read_lock(&dax_srcu); +} +EXPORT_SYMBOL_GPL(dax_read_lock); + +void dax_read_unlock(int id) +{ + srcu_read_unlock(&dax_srcu, id); +} +EXPORT_SYMBOL_GPL(dax_read_unlock); + /** * struct dax_inode - anchor object for dax services * @inode: core vfs @@ -45,8 +58,7 @@ struct dax_inode { bool dax_inode_alive(struct dax_inode *dax_inode) { - RCU_LOCKDEP_WARN(!rcu_read_lock_held(), - "dax operations require rcu_read_lock()\n"); + lockdep_assert_held(&dax_srcu); return dax_inode->alive; } EXPORT_SYMBOL_GPL(dax_inode_alive); @@ -55,7 +67,7 @@ EXPORT_SYMBOL_GPL(dax_inode_alive); * Note, rcu is not protecting the liveness of dax_inode, rcu is * ensuring that any fault handlers or operations that might have seen * dax_inode_alive(), have completed. Any operations that start after - * synchronize_rcu() has run will abort upon seeing !dax_inode_alive(). + * synchronize_srcu() has run will abort upon seeing !dax_inode_alive(). */ void kill_dax_inode(struct dax_inode *dax_inode) { @@ -63,7 +75,7 @@ void kill_dax_inode(struct dax_inode *dax_inode) return; dax_inode->alive = false; - synchronize_rcu(); + synchronize_srcu(&dax_srcu); dax_inode->private = NULL; } EXPORT_SYMBOL_GPL(kill_dax_inode); diff --git a/include/linux/dax.h b/include/linux/dax.h index 24ad71173995..67002898d130 100644 --- a/include/linux/dax.h +++ b/include/linux/dax.h @@ -8,6 +8,9 @@ struct iomap_ops; +int dax_read_lock(void); +void dax_read_unlock(int id); + /* * We use lowest available bit in exceptional entry for locking, one bit for * the entry size (PMD) and two more to tell us if the entry is a huge zero