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[Qemu-devel] [PATCH V9 4/6] util/mmap-alloc: support MAP_SYNC in qemu_ra
From: |
Zhang Yi |
Subject: |
[Qemu-devel] [PATCH V9 4/6] util/mmap-alloc: support MAP_SYNC in qemu_ram_mmap() |
Date: |
Wed, 16 Jan 2019 16:10:58 +0800 |
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).
Signed-off-by: Haozhong Zhang <address@hidden>
Signed-off-by: Zhang Yi <address@hidden>
---
include/qemu/mmap-alloc.h | 1 +
include/qemu/osdep.h | 16 ++++++++++++++++
util/mmap-alloc.c | 7 ++++++-
3 files changed, 23 insertions(+), 1 deletion(-)
diff --git a/include/qemu/mmap-alloc.h b/include/qemu/mmap-alloc.h
index 6fe6ed4..a95d91c 100644
--- a/include/qemu/mmap-alloc.h
+++ b/include/qemu/mmap-alloc.h
@@ -18,6 +18,7 @@ size_t qemu_mempath_getpagesize(const char *mem_path);
* @flags: specifies additional properties of the mapping, which can be one or
* bit-or of following values
* - RAM_SHARED: mmap with MAP_SHARED flag
+ * - RAM_PMEM: mmap with MAP_SYNC flag
* Other bits are ignored.
*
* Return:
diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
index 457d24e..27a6bfe 100644
--- a/include/qemu/osdep.h
+++ b/include/qemu/osdep.h
@@ -419,6 +419,22 @@ void qemu_anon_ram_free(void *ptr, size_t size);
# define QEMU_VMALLOC_ALIGN getpagesize()
#endif
+/*
+ * MAP_SHARED_VALIDATE and MAP_SYNC are introduced in Linux kernel
+ * 4.15, so they may not be defined when compiling on older kernels.
+ */
+#ifdef CONFIG_LINUX
+
+#include <asm-generic/mman.h>
+
+#ifndef MAP_SYNC
+#define MAP_SYNC 0x0
+#endif
+
+#else /* !CONFIG_LINUX */
+#define MAP_SYNC 0x0
+#endif /* CONFIG_LINUX */
+
#ifdef CONFIG_POSIX
struct qemu_signalfd_siginfo {
uint32_t ssi_signo; /* Signal number */
diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c
index 8f0a740..cba961c 100644
--- a/util/mmap-alloc.c
+++ b/util/mmap-alloc.c
@@ -99,6 +99,8 @@ void *qemu_ram_mmap(int fd, size_t size, size_t align,
uint32_t flags)
void *ptr = mmap(0, total, PROT_NONE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
#endif
bool shared = flags & RAM_SHARED;
+ bool is_pmem = flags & RAM_PMEM;
+ int mmap_xflags = 0;
size_t offset;
void *ptr1;
@@ -109,12 +111,15 @@ void *qemu_ram_mmap(int fd, size_t size, size_t align,
uint32_t flags)
assert(is_power_of_2(align));
/* Always align to host page size */
assert(align >= getpagesize());
+ if (shared && is_pmem) {
+ mmap_xflags |= MAP_SYNC;
+ }
offset = QEMU_ALIGN_UP((uintptr_t)ptr, align) - (uintptr_t)ptr;
ptr1 = mmap(ptr + offset, size, PROT_READ | PROT_WRITE,
MAP_FIXED |
(fd == -1 ? MAP_ANONYMOUS : 0) |
- (shared ? MAP_SHARED : MAP_PRIVATE),
+ (shared ? MAP_SHARED : MAP_PRIVATE) | mmap_xflags,
fd, 0);
if (ptr1 == MAP_FAILED) {
munmap(ptr, total);
--
2.7.4
- Re: [Qemu-devel] [PATCH V9 2/6] memory: use sparse feature define RAM_FLAG., (continued)
[Qemu-devel] [PATCH V9 3/6] util/mmap-alloc: switch 'shared' to 'flags' parameter, Zhang Yi, 2019/01/16
[Qemu-devel] [PATCH V9 6/6] docs: Added MAP_SYNC documentation, Zhang Yi, 2019/01/16
[Qemu-devel] [PATCH V9 4/6] util/mmap-alloc: support MAP_SYNC in qemu_ram_mmap(),
Zhang Yi <=
- Re: [Qemu-devel] [PATCH V9 4/6] util/mmap-alloc: support MAP_SYNC in qemu_ram_mmap(), Michael S. Tsirkin, 2019/01/16
- Re: [Qemu-devel] [PATCH V9 4/6] util/mmap-alloc: support MAP_SYNC in qemu_ram_mmap(), Eduardo Habkost, 2019/01/18
- Re: [Qemu-devel] [PATCH V9 4/6] util/mmap-alloc: support MAP_SYNC in qemu_ram_mmap(), Yi Zhang, 2019/01/21
- Re: [Qemu-devel] [PATCH V9 4/6] util/mmap-alloc: support MAP_SYNC in qemu_ram_mmap(), Eduardo Habkost, 2019/01/21
- Re: [Qemu-devel] [PATCH V9 4/6] util/mmap-alloc: support MAP_SYNC in qemu_ram_mmap(), Yi Zhang, 2019/01/21
- Re: [Qemu-devel] [PATCH V9 4/6] util/mmap-alloc: support MAP_SYNC in qemu_ram_mmap(), Michael S. Tsirkin, 2019/01/21
- Re: [Qemu-devel] [PATCH V9 4/6] util/mmap-alloc: support MAP_SYNC in qemu_ram_mmap(), Dan Williams, 2019/01/22
- Re: [Qemu-devel] [PATCH V9 4/6] util/mmap-alloc: support MAP_SYNC in qemu_ram_mmap(), Michael S. Tsirkin, 2019/01/22
[Qemu-devel] [PATCH V9 5/6] hostmem: add more information in error messages, Zhang Yi, 2019/01/16