From: "Zhang,Yi" <yi.z.zh...@linux.intel.com>
Linux 4.15 introduces a new mmap flag MAP_SYNC, which can be used to
guarantee the write persistence to mmap'ed files supporting DAX (e.g.,
files on ext4/xfs file system mounted with '-o dax').
A description of MAP_SYNC and MAP_SHARED_VALIDATE can be found at
https://patchwork.kernel.org/patch/10028151/
In order to make sure that the file metadata is in sync after a fault
while we are writing a shared DAX supporting backend files, this
patch-set enables QEMU to use MAP_SYNC flag for memory-backend-dax-file.
As the DAX vs DMA truncated issue was solved, we refined the code and
send out this feature for the v5 version.
We will pass MAP_SYNC to mmap(2); if MAP_SYNC is supported and
'share=on' & 'pmem=on'.
Or QEMU will not pass this flag to mmap(2)
Changes in V10:
* 4/4: refine the document.
* 3/4: Reviewed-by: Stefano Garzarella <sgarz...@redhat.com>
* 2/4: refine the commit message, Added MAP_SHARED_VALIDATE.
* 2/4: Fix the wrong include header
Changes in V9:
* 1/6: Reviewed-by: Eduardo Habkost <ehabk...@redhat.com>
* 2/6: New Added: Micheal: use sparse feature define RAM_FLAG.
since I don't have much knowledge about the sparse feature, @Micheal Could you
add some documentation/commit message on this patch? Thank you very much.
* 3/6: from 2/5: Eduardo: updated the commit message.
* 4/6: from 3/5: Micheal: don't ignore MAP_SYNC failures silently.
* 5/6: from 4/5: Eduardo: updated the commit message.
* 6/6: from 5/5: Micheal: Drop the sync option, document the MAP_SYNC.
Changes in v8:
* Micheal: 3/5, remove the duplicated define in the os_dep.h
* Micheal: 2/5, make type define safety.
* Micheal: 2/5, fixed the incorrect define MAP_SHARE on qemu_anon_ram_alloc.
* 4/6 removed, we remove the on/off/auto define of sync, as by now,
MAP_SYNC only worked with pmem=on.
* @Micheal, I still reuse the RAM_SYNC flag, it is much straightforward to
parse
all the flags in one parameter.
Changes in v7:
* Micheal: [3,4,6]/6 limited the "sync" flag only on a nvdimm backend.(pmem=on)
Changes in v6:
* Pankaj: 3/7 are squashed with 2/7
* Pankaj: 7/7 update comments to "consistent filesystem metadata".
* Pankaj, Igor: 1/7 Added Reviewed-by in patch-1/7
* Stefan, 4/7 move the include header from "/linux/mman.h" to "osdep.h"
* Stefan, 5/7 Add missing "munmap"
* Stefan, 2/7 refine the shared/flag.
Changes in v5:
* Add patch 1 to fix a memory leak issue.
* Refine the patch 4-6
* Remove the patch 3 as we already change the parameter from "shared" to
"flags"
Changes in v4:
* Add patch 1-3 to switch some functions to a single 'flags'
parameters. (Michael S. Tsirkin)
* v3 patch 1-3 become v4 patch 4-6.
* Patch 4: move definitions of MAP_SYNC and MAP_SHARED_VALIDATE to a
new header file under include/standard-headers/linux/. (Michael S. Tsirkin)
* Patch 6: refine the description of the 'sync' option. (Michael S. Tsirkin)
Changes in v3:
* Patch 1: add MAP_SHARED_VALIDATE in both sync=on and sync=auto
cases, and add back the retry mechanism. MAP_SYNC will be ignored
by Linux kernel 4.15 if MAP_SHARED_VALIDATE is missed.
* Patch 1: define MAP_SYNC and MAP_SHARED_VALIDATE as 0 on non-Linux
platforms in order to make qemu_ram_mmap() compile on those platforms.
* Patch 2&3: include more information in error messages of
memory-backend in hope to help user to identify the error.
(Dr. David Alan Gilbert)
* Patch 3: fix typo in the commit message. (Dr. David Alan Gilbert)
Changes in v2:
* Add 'sync' option to control the use of MAP_SYNC. (Eduardo Habkost)
* Remove the unnecessary set of MAP_SHARED_VALIDATE in some cases and
the retry mechanism in qemu_ram_mmap(). (Michael S. Tsirkin)
* Move OS dependent definitions of MAP_SYNC and MAP_SHARED_VALIDATE
to osdep.h. (Michael S. Tsirkin)
Zhang Yi (4):
util/mmap-alloc: switch 'shared' to 'flags' parameter
util/mmap-alloc: support MAP_SYNC in qemu_ram_mmap()
hostmem: add more information in error messages
docs: Added MAP_SYNC documentation
backends/hostmem-file.c | 6 ++++--
backends/hostmem.c | 8 +++++---
docs/nvdimm.txt | 29 ++++++++++++++++++++++++++++-
exec.c | 7 ++++---
include/qemu/mmap-alloc.h | 20 +++++++++++++++++++-
include/qemu/osdep.h | 21 +++++++++++++++++++++
qemu-options.hx | 4 ++++
util/mmap-alloc.c | 15 +++++++++++----
util/oslib-posix.c | 9 ++++++++-
9 files changed, 104 insertions(+), 15 deletions(-)
--
2.7.4
