From patchwork Wed Oct 12 22:50:09 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ross Zwisler X-Patchwork-Id: 9373931 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 AAF27608A0 for ; Wed, 12 Oct 2016 22:51:00 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 84BD2293BC for ; Wed, 12 Oct 2016 22:51:00 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 790422978B; Wed, 12 Oct 2016 22:51:00 +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 1A29229754 for ; Wed, 12 Oct 2016 22:51:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933478AbcJLWus (ORCPT ); Wed, 12 Oct 2016 18:50:48 -0400 Received: from mga07.intel.com ([134.134.136.100]:51988 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933226AbcJLWuc (ORCPT ); Wed, 12 Oct 2016 18:50:32 -0400 Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga105.jf.intel.com with ESMTP; 12 Oct 2016 15:50:30 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.31,485,1473145200"; d="scan'208";a="1064028037" Received: from rzwisler-desk1.amr.corp.intel.com (HELO tarkir.intel.com) ([10.252.205.93]) by orsmga002.jf.intel.com with ESMTP; 12 Oct 2016 15:50:30 -0700 From: Ross Zwisler To: linux-kernel@vger.kernel.org Cc: Ross Zwisler , "Theodore Ts'o" , Alexander Viro , Andreas Dilger , Andrew Morton , Christoph Hellwig , Dan Williams , Dave Chinner , Jan Kara , Matthew Wilcox , linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-nvdimm@lists.01.org, linux-xfs@vger.kernel.org Subject: [PATCH v6 04/17] ext2: remove support for DAX PMD faults Date: Wed, 12 Oct 2016 16:50:09 -0600 Message-Id: <20161012225022.15507-5-ross.zwisler@linux.intel.com> X-Mailer: git-send-email 2.9.0 In-Reply-To: <20161012225022.15507-1-ross.zwisler@linux.intel.com> References: <20161012225022.15507-1-ross.zwisler@linux.intel.com> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP DAX PMD support was added via the following commit: commit e7b1ea2ad658 ("ext2: huge page fault support") I believe this path to be untested as ext2 doesn't reliably provide block allocations that are aligned to 2MiB. In my testing I've been unable to get ext2 to actually fault in a PMD. It always fails with a "pfn unaligned" message because the sector returned by ext2_get_block() isn't aligned. I've tried various settings for the "stride" and "stripe_width" extended options to mkfs.ext2, without any luck. Since we can't reliably get PMDs, remove support so that we don't have an untested code path that we may someday traverse when we happen to get an aligned block allocation. This should also make 4k DAX faults in ext2 a bit faster since they will no longer have to call the PMD fault handler only to get a response of VM_FAULT_FALLBACK. Signed-off-by: Ross Zwisler Reviewed-by: Christoph Hellwig Reviewed-by: Jan Kara --- fs/ext2/file.c | 29 ++++++----------------------- 1 file changed, 6 insertions(+), 23 deletions(-) diff --git a/fs/ext2/file.c b/fs/ext2/file.c index 0ca363d..0f257f8 100644 --- a/fs/ext2/file.c +++ b/fs/ext2/file.c @@ -107,27 +107,6 @@ static int ext2_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf) return ret; } -static int ext2_dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr, - pmd_t *pmd, unsigned int flags) -{ - struct inode *inode = file_inode(vma->vm_file); - struct ext2_inode_info *ei = EXT2_I(inode); - int ret; - - if (flags & FAULT_FLAG_WRITE) { - sb_start_pagefault(inode->i_sb); - file_update_time(vma->vm_file); - } - down_read(&ei->dax_sem); - - ret = dax_pmd_fault(vma, addr, pmd, flags, ext2_get_block); - - up_read(&ei->dax_sem); - if (flags & FAULT_FLAG_WRITE) - sb_end_pagefault(inode->i_sb); - return ret; -} - static int ext2_dax_pfn_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf) { @@ -154,7 +133,11 @@ static int ext2_dax_pfn_mkwrite(struct vm_area_struct *vma, static const struct vm_operations_struct ext2_dax_vm_ops = { .fault = ext2_dax_fault, - .pmd_fault = ext2_dax_pmd_fault, + /* + * .pmd_fault is not supported for DAX because allocation in ext2 + * cannot be reliably aligned to huge page sizes and so pmd faults + * will always fail and fail back to regular faults. + */ .page_mkwrite = ext2_dax_fault, .pfn_mkwrite = ext2_dax_pfn_mkwrite, }; @@ -166,7 +149,7 @@ static int ext2_file_mmap(struct file *file, struct vm_area_struct *vma) file_accessed(file); vma->vm_ops = &ext2_dax_vm_ops; - vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE; + vma->vm_flags |= VM_MIXEDMAP; return 0; } #else