From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756829AbbJVGr5 (ORCPT ); Thu, 22 Oct 2015 02:47:57 -0400 Received: from mga03.intel.com ([134.134.136.65]:40701 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756789AbbJVGry (ORCPT ); Thu, 22 Oct 2015 02:47:54 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.20,181,1444719600"; d="scan'208";a="832769042" Subject: [PATCH 5/5] block: enable dax for raw block devices From: Dan Williams To: axboe@fb.com Cc: jack@suse.cz, linux-nvdimm@ml01.01.org, david@fromorbit.com, linux-kernel@vger.kernel.org, hch@lst.de, Jeff Moyer , willy@linux.intel.com, ross.zwisler@linux.intel.com, akpm@linux-foundation.org Date: Thu, 22 Oct 2015 02:42:11 -0400 Message-ID: <20151022064211.12700.77105.stgit@dwillia2-desk3.amr.corp.intel.com> In-Reply-To: <20151022064142.12700.11849.stgit@dwillia2-desk3.amr.corp.intel.com> References: <20151022064142.12700.11849.stgit@dwillia2-desk3.amr.corp.intel.com> User-Agent: StGit/0.17.1-9-g687f MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If an application wants exclusive access to all of the persistent memory provided by an NVDIMM namespace it can use this raw-block-dax facility to forgo establishing a filesystem. This capability is targeted primarily to hypervisors wanting to provision persistent memory for guests. Cc: Jan Kara Cc: Jeff Moyer Cc: Christoph Hellwig Cc: Dave Chinner Cc: Andrew Morton Cc: Ross Zwisler Signed-off-by: Dan Williams --- fs/block_dev.c | 54 +++++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 53 insertions(+), 1 deletion(-) diff --git a/fs/block_dev.c b/fs/block_dev.c index 3255dcec96b4..c27cd1a21a13 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -1687,13 +1687,65 @@ static const struct address_space_operations def_blk_aops = { .is_dirty_writeback = buffer_check_dirty_writeback, }; +#ifdef CONFIG_FS_DAX +/* + * In the raw block case we do not need to contend with truncation nor + * unwritten file extents. Without those concerns there is no need for + * additional locking beyond the mmap_sem context that these routines + * are already executing under. + * + * Note, there is no protection if the block device is dynamically + * resized (partition grow/shrink) during a fault. A stable block device + * size is already not enforced in the blkdev_direct_IO path. + * + * For DAX, it is the responsibility of the block device driver to + * ensure the whole-disk device size is stable while requests are in + * flight. + * + * Finally, these paths do not synchronize against freezing + * (sb_start_pagefault(), etc...) since bdev_sops does not support + * freezing. + */ +static int blkdev_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf) +{ + return __dax_fault(vma, vmf, blkdev_get_block, NULL); +} + +static int blkdev_dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr, + pmd_t *pmd, unsigned int flags) +{ + return __dax_pmd_fault(vma, addr, pmd, flags, blkdev_get_block, NULL); +} + +static const struct vm_operations_struct blkdev_dax_vm_ops = { + .page_mkwrite = blkdev_dax_fault, + .fault = blkdev_dax_fault, + .pmd_fault = blkdev_dax_pmd_fault, +}; + +static int blkdev_mmap(struct file *file, struct vm_area_struct *vma) +{ + struct inode *bd_inode = file_bd_inode(file); + + if (!IS_DAX(bd_inode)) + return generic_file_mmap(file, vma); + + file_accessed(file); + vma->vm_ops = &blkdev_dax_vm_ops; + vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE; + return 0; +} +#else +#define blkdev_mmap generic_file_mmap +#endif + const struct file_operations def_blk_fops = { .open = blkdev_open, .release = blkdev_close, .llseek = block_llseek, .read_iter = blkdev_read_iter, .write_iter = blkdev_write_iter, - .mmap = generic_file_mmap, + .mmap = blkdev_mmap, .fsync = blkdev_fsync, .unlocked_ioctl = block_ioctl, #ifdef CONFIG_COMPAT