From patchwork Tue Nov 1 19:54:05 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ross Zwisler X-Patchwork-Id: 9407889 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 DFFDF60721 for ; Tue, 1 Nov 2016 19:54:30 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id CE4F729A7C for ; Tue, 1 Nov 2016 19:54:30 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C2DCC29A8C; Tue, 1 Nov 2016 19:54:30 +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=-1.9 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 Received: from ml01.01.org (ml01.01.org [198.145.21.10]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 654DC29A8C for ; Tue, 1 Nov 2016 19:54:30 +0000 (UTC) Received: from [127.0.0.1] (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id 1997681D36; Tue, 1 Nov 2016 12:54:28 -0700 (PDT) X-Original-To: linux-nvdimm@lists.01.org Delivered-To: linux-nvdimm@lists.01.org Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) (using TLSv1 with cipher CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 000EB81D2F for ; Tue, 1 Nov 2016 12:54:26 -0700 (PDT) Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga103.fm.intel.com with ESMTP; 01 Nov 2016 12:54:28 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.31,433,1473145200"; d="scan'208";a="186453082" Received: from theros.lm.intel.com ([10.232.112.77]) by fmsmga004.fm.intel.com with ESMTP; 01 Nov 2016 12:54:27 -0700 From: Ross Zwisler To: linux-kernel@vger.kernel.org Subject: [PATCH v9 03/16] ext2: remove support for DAX PMD faults Date: Tue, 1 Nov 2016 13:54:05 -0600 Message-Id: <1478030058-1422-4-git-send-email-ross.zwisler@linux.intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1478030058-1422-1-git-send-email-ross.zwisler@linux.intel.com> References: <1478030058-1422-1-git-send-email-ross.zwisler@linux.intel.com> X-BeenThere: linux-nvdimm@lists.01.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: "Linux-nvdimm developer list." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Theodore Ts'o , Matthew Wilcox , Dave Chinner , linux-nvdimm@lists.01.org, Christoph Hellwig , linux-xfs@vger.kernel.org, linux-mm@kvack.org, Andreas Dilger , Alexander Viro , linux-fsdevel@vger.kernel.org, Jan Kara , linux-ext4@vger.kernel.org, Andrew Morton MIME-Version: 1.0 Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" 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 a0e1478..fb88b51 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