From patchwork Fri Nov 4 04:25:17 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jan Kara X-Patchwork-Id: 9411887 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 CE76B60585 for ; Fri, 4 Nov 2016 04:25:55 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id BE30F2AC9E for ; Fri, 4 Nov 2016 04:25:55 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id B31662ACA4; Fri, 4 Nov 2016 04:25:55 +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 5E90B2AC9E for ; Fri, 4 Nov 2016 04:25:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757982AbcKDEZm (ORCPT ); Fri, 4 Nov 2016 00:25:42 -0400 Received: from mx2.suse.de ([195.135.220.15]:44714 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755089AbcKDEZa (ORCPT ); Fri, 4 Nov 2016 00:25:30 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id B0E06ADC4; Fri, 4 Nov 2016 04:25:26 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id C3EF01E0FE9; Fri, 4 Nov 2016 05:25:20 +0100 (CET) From: Jan Kara To: Cc: , linux-nvdimm@lists.01.org, Andrew Morton , Ross Zwisler , "Kirill A. Shutemov" , Jan Kara Subject: [PATCH 21/21] dax: Clear dirty entry tags on cache flush Date: Fri, 4 Nov 2016 05:25:17 +0100 Message-Id: <1478233517-3571-22-git-send-email-jack@suse.cz> X-Mailer: git-send-email 2.6.6 In-Reply-To: <1478233517-3571-1-git-send-email-jack@suse.cz> References: <1478233517-3571-1-git-send-email-jack@suse.cz> 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 Currently we never clear dirty tags in DAX mappings and thus address ranges to flush accumulate. Now that we have locking of radix tree entries, we have all the locking necessary to reliably clear the radix tree dirty tag when flushing caches for corresponding address range. Similarly to page_mkclean() we also have to write-protect pages to get a page fault when the page is next written to so that we can mark the entry dirty again. Reviewed-by: Ross Zwisler Signed-off-by: Jan Kara --- fs/dax.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 64 insertions(+) diff --git a/fs/dax.c b/fs/dax.c index 7b00316ebf49..263f4e1671ca 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -31,6 +31,7 @@ #include #include #include +#include #include #include "internal.h" @@ -615,6 +616,59 @@ static void *dax_insert_mapping_entry(struct address_space *mapping, return new_entry; } +static inline unsigned long +pgoff_address(pgoff_t pgoff, struct vm_area_struct *vma) +{ + unsigned long address; + + address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); + VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma); + return address; +} + +/* Walk all mappings of a given index of a file and writeprotect them */ +static void dax_mapping_entry_mkclean(struct address_space *mapping, + pgoff_t index, unsigned long pfn) +{ + struct vm_area_struct *vma; + pte_t *ptep; + pte_t pte; + spinlock_t *ptl; + bool changed; + + i_mmap_lock_read(mapping); + vma_interval_tree_foreach(vma, &mapping->i_mmap, index, index) { + unsigned long address; + + cond_resched(); + + if (!(vma->vm_flags & VM_SHARED)) + continue; + + address = pgoff_address(index, vma); + changed = false; + if (follow_pte(vma->vm_mm, address, &ptep, &ptl)) + continue; + if (pfn != pte_pfn(*ptep)) + goto unlock; + if (!pte_dirty(*ptep) && !pte_write(*ptep)) + goto unlock; + + flush_cache_page(vma, address, pfn); + pte = ptep_clear_flush(vma, address, ptep); + pte = pte_wrprotect(pte); + pte = pte_mkclean(pte); + set_pte_at(vma->vm_mm, address, ptep, pte); + changed = true; +unlock: + pte_unmap_unlock(ptep, ptl); + + if (changed) + mmu_notifier_invalidate_page(vma->vm_mm, address); + } + i_mmap_unlock_read(mapping); +} + static int dax_writeback_one(struct block_device *bdev, struct address_space *mapping, pgoff_t index, void *entry) { @@ -688,7 +742,17 @@ static int dax_writeback_one(struct block_device *bdev, goto unmap; } + dax_mapping_entry_mkclean(mapping, index, pfn_t_to_pfn(dax.pfn)); wb_cache_pmem(dax.addr, dax.size); + /* + * After we have flushed the cache, we can clear the dirty tag. There + * cannot be new dirty data in the pfn after the flush has completed as + * the pfn mappings are writeprotected and fault waits for mapping + * entry lock. + */ + spin_lock_irq(&mapping->tree_lock); + radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_DIRTY); + spin_unlock_irq(&mapping->tree_lock); unmap: dax_unmap_atomic(bdev, &dax); put_locked_mapping_entry(mapping, index, entry);