From patchwork Fri Apr 26 00:36:51 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wei Yang X-Patchwork-Id: 1091167 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=linux.intel.com Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 44qwCf4wN9z9s47 for ; Fri, 26 Apr 2019 10:38:54 +1000 (AEST) Received: from localhost ([127.0.0.1]:37172 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hJot6-0000iK-Sx for incoming@patchwork.ozlabs.org; Thu, 25 Apr 2019 20:38:48 -0400 Received: from eggs.gnu.org ([209.51.188.92]:33098) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hJosP-0000ho-Dr for qemu-devel@nongnu.org; Thu, 25 Apr 2019 20:38:06 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hJosO-0007gs-7r for qemu-devel@nongnu.org; Thu, 25 Apr 2019 20:38:05 -0400 Received: from mga02.intel.com ([134.134.136.20]:16691) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hJosN-0007fU-UX for qemu-devel@nongnu.org; Thu, 25 Apr 2019 20:38:04 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 25 Apr 2019 17:38:02 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,395,1549958400"; d="scan'208";a="340872201" Received: from richard.sh.intel.com (HELO localhost) ([10.239.159.54]) by fmsmga005.fm.intel.com with ESMTP; 25 Apr 2019 17:38:00 -0700 From: Wei Yang To: qemu-devel@nongnu.org Date: Fri, 26 Apr 2019 08:36:51 +0800 Message-Id: <20190426003652.32633-2-richardw.yang@linux.intel.com> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190426003652.32633-1-richardw.yang@linux.intel.com> References: <20190426003652.32633-1-richardw.yang@linux.intel.com> MIME-Version: 1.0 X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 134.134.136.20 Subject: [Qemu-devel] [PATCH v15 1/2] util/mmap-alloc: support MAP_SYNC in qemu_ram_mmap() X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: pagupta@redhat.com, xiaoguangrong.eric@gmail.com, mst@redhat.com, Haozhong Zhang , yi.z.zhang@linux.intel.com, yu.c.zhang@linux.intel.com, richardw.yang@linux.intel.com, stefanha@redhat.com, imammedo@redhat.com, pbonzini@redhat.com, dan.j.williams@intel.com, ehabkost@redhat.com Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" From: Zhang Yi When a file supporting DAX is used as vNVDIMM backend, mmap it with MAP_SYNC flag in addition which can ensure file system metadata synced in each guest writes to the backend file, without other QEMU actions (e.g., periodic fsync() by QEMU). Current, We have below different possible use cases: 1. pmem=on is set, shared=on is set, MAP_SYNC supported: a: backend is a dax supporting file. - MAP_SYNC will active. b: backend is not a dax supporting file. - mmap will trigger a warning. then MAP_SYNC flag will be ignored 2. The rest of cases: - we will never pass the MAP_SYNC to mmap2 Signed-off-by: Haozhong Zhang Signed-off-by: Zhang Yi [ehabkost: Rebased patch to latest code on master] Signed-off-by: Eduardo Habkost Signed-off-by: Wei Yang Tested-by: Wei Yang Reviewed-by: Stefan Hajnoczi --- v15: fix compile issue on pre-linux4.15 v14: rebase on top of current upstream --- util/mmap-alloc.c | 45 ++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 44 insertions(+), 1 deletion(-) diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c index 9713f4b960..b8f94d618a 100644 --- a/util/mmap-alloc.c +++ b/util/mmap-alloc.c @@ -10,6 +10,17 @@ * later. See the COPYING file in the top-level directory. */ +#ifdef CONFIG_LINUX +#include +#endif /* CONFIG_LINUX */ + +#ifndef MAP_SYNC +#define MAP_SYNC 0 +#endif +#ifndef MAP_SHARED_VALIDATE +#define MAP_SHARED_VALIDATE 0 +#endif + #include "qemu/osdep.h" #include "qemu/mmap-alloc.h" #include "qemu/host-utils.h" @@ -82,6 +93,7 @@ void *qemu_ram_mmap(int fd, bool is_pmem) { int flags; + int map_sync_flags = 0; int guardfd; size_t offset; size_t pagesize; @@ -132,9 +144,40 @@ void *qemu_ram_mmap(int fd, flags = MAP_FIXED; flags |= fd == -1 ? MAP_ANONYMOUS : 0; flags |= shared ? MAP_SHARED : MAP_PRIVATE; + if (shared && is_pmem) { + map_sync_flags = MAP_SYNC | MAP_SHARED_VALIDATE; + } + offset = QEMU_ALIGN_UP((uintptr_t)guardptr, align) - (uintptr_t)guardptr; - ptr = mmap(guardptr + offset, size, PROT_READ | PROT_WRITE, flags, fd, 0); + ptr = mmap(guardptr + offset, size, PROT_READ | PROT_WRITE, + flags | map_sync_flags, fd, 0); + + if (ptr == MAP_FAILED && map_sync_flags) { + if (errno == ENOTSUP) { + char *proc_link, *file_name; + int len; + proc_link = g_strdup_printf("/proc/self/fd/%d", fd); + file_name = g_malloc0(PATH_MAX); + len = readlink(proc_link, file_name, PATH_MAX - 1); + if (len < 0) { + len = 0; + } + file_name[len] = '\0'; + fprintf(stderr, "Warning: requesting persistence across crashes " + "for backend file %s failed. Proceeding without " + "persistence, data might become corrupted in case of host " + "crash.\n", file_name); + g_free(proc_link); + g_free(file_name); + } + /* + * if map failed with MAP_SHARED_VALIDATE | MAP_SYNC, + * we will remove these flags to handle compatibility. + */ + ptr = mmap(guardptr + offset, size, PROT_READ | PROT_WRITE, + flags, fd, 0); + } if (ptr == MAP_FAILED) { munmap(guardptr, total);