Ping for any review/comments
Thanks
Yi
On 2018-11-20 at 15:47:58 +0800, Zhang Yi wrote:
> 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.
>
> A new auto on/off option 'sync' is added to memory-backend-file:
> - on: try to pass MAP_SYNC to mmap(2); if MAP_SYNC is not supported or
> 'share=off', QEMU will abort
> - off: never pass MAP_SYNC to mmap(2)
> - auto (default): if MAP_SYNC is supported and 'share=on', work as if
> 'sync=on'; otherwise, work as if 'sync=off'
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 (7):
> numa: Fixed the memory leak of numa error message
> util/mmap-alloc: switch qemu_ram_mmap() to 'flags' parameter
> exec: switch qemu_ram_alloc_from_{file, fd} to the 'flags' parameter
> util/mmap-alloc: support MAP_SYNC in qemu_ram_mmap()
> util/mmap-alloc: Switch the RAM_SYNC flags to OnOffAuto
> hostmem: add more information in error messages
> hostmem-file: add 'sync' option
>
> backends/hostmem-file.c | 45
> +++++++++++++++++++++++++++++++++--
> backends/hostmem.c | 8 ++++---
> docs/nvdimm.txt | 20 +++++++++++++++-
> exec.c | 9 +++----
> include/exec/memory.h | 18 ++++++++++++++
> include/exec/ram_addr.h | 1 +
> include/qemu/mmap-alloc.h | 20 +++++++++++++++-
> include/standard-headers/linux/mman.h | 44 ++++++++++++++++++++++++++++++++++
> numa.c | 1 +
> qemu-options.hx | 22 ++++++++++++++++-
> util/mmap-alloc.c | 26 ++++++++++++++++----
> util/oslib-posix.c | 4 +++-
> 12 files changed, 200 insertions(+), 18 deletions(-)
> create mode 100644 include/standard-headers/linux/mman.h
>
> --
> 2.7.4
>
