| Message ID | 5d07bf7e9a3e576f5a87e81d786e8886fb2bb551.1549555521.git.yi.z.zhang@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | support MAP_SYNC for memory-backend-file | expand |
Hi,
I found out that this series missed QEMU 4.0 and I was going to
queue for 4.1, but unfortunately this patch conflicts with:
commit 2044c3e7116eeac0449dcb4a4130cc8f8b9310da
Author: Murilo Opsfelder Araujo <muriloo@linux.ibm.com>
Date: Wed Jan 30 21:36:04 2019 -0200
mmap-alloc: unfold qemu_ram_mmap()
Unfold parts of qemu_ram_mmap() for the sake of understanding, moving
declarations to the top, and keeping architecture-specifics in the
ifdef-else blocks. No changes in the function behaviour.
Give ptr and ptr1 meaningful names:
ptr -> guardptr : pointer to the PROT_NONE guard region
ptr1 -> ptr : pointer to the mapped memory returned to caller
Signed-off-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
I'm queueing patches 1-3 into machine-next[1], so only patches 4
and 5 need to be refreshed and resubmitted.
[1] https://github.com/ehabkost/qemu.git machine-next
On Fri, Feb 08, 2019 at 06:11:11PM +0800, Zhang, Yi wrote:
> From: Zhang Yi <yi.z.zhang@linux.intel.com>
>
> 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 <haozhong.zhang@intel.com>
> Signed-off-by: Zhang Yi <yi.z.zhang@linux.intel.com>
> ---
> 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 97bbeed..2f21efd 100644
> --- a/util/mmap-alloc.c
> +++ b/util/mmap-alloc.c
> @@ -10,6 +10,13 @@
> * later. See the COPYING file in the top-level directory.
> */
>
> +#ifdef CONFIG_LINUX
> +#include <linux/mman.h>
> +#else /* !CONFIG_LINUX */
> +#define MAP_SYNC 0x0
> +#define MAP_SHARED_VALIDATE 0x0
> +#endif /* CONFIG_LINUX */
> +
> #include "qemu/osdep.h"
> #include "qemu/mmap-alloc.h"
> #include "qemu/host-utils.h"
> @@ -101,6 +108,8 @@ void *qemu_ram_mmap(int fd,
> #else
> void *ptr = mmap(0, total, PROT_NONE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
> #endif
> + int mmap_flags;
> + int map_sync_flags = 0;
> size_t offset;
> void *ptr1;
>
> @@ -111,13 +120,47 @@ void *qemu_ram_mmap(int fd,
> assert(is_power_of_2(align));
> /* Always align to host page size */
> assert(align >= getpagesize());
> + mmap_flags = shared ? MAP_SHARED : MAP_PRIVATE;
> + if (shared && is_pmem) {
> + map_sync_flags = MAP_SYNC | MAP_SHARED_VALIDATE;
> + mmap_flags |= map_sync_flags;
> + }
>
> 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),
> + mmap_flags,
> fd, 0);
> +
> +
> + if (ptr1 == 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.
> + */
> + ptr1 = mmap(ptr + offset, size, PROT_READ | PROT_WRITE,
> + MAP_FIXED |
> + (fd == -1 ? MAP_ANONYMOUS : 0) |
> + MAP_SHARED,
> + fd, 0);
> + }
> if (ptr1 == MAP_FAILED) {
> munmap(ptr, total);
> return MAP_FAILED;
> --
> 2.7.4
>
>
On Thu, Apr 18, 2019 at 07:05:16PM -0300, Eduardo Habkost wrote: > Hi, > > I found out that this series missed QEMU 4.0 and I was going to > queue for 4.1, but unfortunately this patch conflicts with: > > commit 2044c3e7116eeac0449dcb4a4130cc8f8b9310da > Author: Murilo Opsfelder Araujo <muriloo@linux.ibm.com> > Date: Wed Jan 30 21:36:04 2019 -0200 > > mmap-alloc: unfold qemu_ram_mmap() [...] > On Fri, Feb 08, 2019 at 06:11:11PM +0800, Zhang, Yi wrote: > > From: Zhang Yi <yi.z.zhang@linux.intel.com> > > > > 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 <haozhong.zhang@intel.com> > > Signed-off-by: Zhang Yi <yi.z.zhang@linux.intel.com> Untested patch rebase is below. Can Intel help test it and submit v14? Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com> Signed-off-by: Zhang Yi <yi.z.zhang@linux.intel.com> [ehabkost: Rebased patch to latest code on master] Signed-off-by: Eduardo Habkost <ehabkost@redhat.com> --- util/mmap-alloc.c | 41 +++++++++++++++++++++++++++++++++++++++-- 1 file changed, 39 insertions(+), 2 deletions(-) diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c index 9713f4b960..7063a44c7d 100644 --- a/util/mmap-alloc.c +++ b/util/mmap-alloc.c @@ -10,6 +10,13 @@ * later. See the COPYING file in the top-level directory. */ +#ifdef CONFIG_LINUX +#include <linux/mman.h> +#else /* !CONFIG_LINUX */ +#define MAP_SYNC 0x0 +#define MAP_SHARED_VALIDATE 0x0 +#endif /* CONFIG_LINUX */ + #include "qemu/osdep.h" #include "qemu/mmap-alloc.h" #include "qemu/host-utils.h" @@ -82,6 +89,7 @@ void *qemu_ram_mmap(int fd, bool is_pmem) { int flags; + int map_sync_flags = 0; int guardfd; size_t offset; size_t pagesize; @@ -132,10 +140,39 @@ 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); return MAP_FAILED;
On Thu, Apr 18, 2019 at 07:33:01PM -0300, Eduardo Habkost wrote: >On Thu, Apr 18, 2019 at 07:05:16PM -0300, Eduardo Habkost wrote: >> Hi, >> >> I found out that this series missed QEMU 4.0 and I was going to >> queue for 4.1, but unfortunately this patch conflicts with: >> >> commit 2044c3e7116eeac0449dcb4a4130cc8f8b9310da >> Author: Murilo Opsfelder Araujo <muriloo@linux.ibm.com> >> Date: Wed Jan 30 21:36:04 2019 -0200 >> >> mmap-alloc: unfold qemu_ram_mmap() >[...] >> On Fri, Feb 08, 2019 at 06:11:11PM +0800, Zhang, Yi wrote: >> > From: Zhang Yi <yi.z.zhang@linux.intel.com> >> > >> > 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 <haozhong.zhang@intel.com> >> > Signed-off-by: Zhang Yi <yi.z.zhang@linux.intel.com> > >Untested patch rebase is below. Can Intel help test it and >submit v14? > Thanks Eduardo, the patch looks good to me and I have tested it.
diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c index 97bbeed..2f21efd 100644 --- a/util/mmap-alloc.c +++ b/util/mmap-alloc.c @@ -10,6 +10,13 @@ * later. See the COPYING file in the top-level directory. */ +#ifdef CONFIG_LINUX +#include <linux/mman.h> +#else /* !CONFIG_LINUX */ +#define MAP_SYNC 0x0 +#define MAP_SHARED_VALIDATE 0x0 +#endif /* CONFIG_LINUX */ + #include "qemu/osdep.h" #include "qemu/mmap-alloc.h" #include "qemu/host-utils.h" @@ -101,6 +108,8 @@ void *qemu_ram_mmap(int fd, #else void *ptr = mmap(0, total, PROT_NONE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0); #endif + int mmap_flags; + int map_sync_flags = 0; size_t offset; void *ptr1; @@ -111,13 +120,47 @@ void *qemu_ram_mmap(int fd, assert(is_power_of_2(align)); /* Always align to host page size */ assert(align >= getpagesize()); + mmap_flags = shared ? MAP_SHARED : MAP_PRIVATE; + if (shared && is_pmem) { + map_sync_flags = MAP_SYNC | MAP_SHARED_VALIDATE; + mmap_flags |= map_sync_flags; + } 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), + mmap_flags, fd, 0); + + + if (ptr1 == 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. + */ + ptr1 = mmap(ptr + offset, size, PROT_READ | PROT_WRITE, + MAP_FIXED | + (fd == -1 ? MAP_ANONYMOUS : 0) | + MAP_SHARED, + fd, 0); + } if (ptr1 == MAP_FAILED) { munmap(ptr, total); return MAP_FAILED;