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Re: [Qemu-devel] [PATCH v5 0/7] nvdimm: support MAP_SYNC for memory-back
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [PATCH v5 0/7] nvdimm: support MAP_SYNC for memory-backend-file |
Date: |
Wed, 5 Dec 2018 09:59:23 +0000 |
User-agent: |
Mutt/1.10.1 (2018-07-13) |
On Mon, Nov 05, 2018 at 04:07:50PM +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').
>
Hi,
There are a lot of people on CC so probably no one felt responsible to
review this series quickly. Feel free to send a "ping" email if your
patches aren't receiving attention.
Overall this feature looks fine. I left a few small comments.
Thanks,
Stefan
> 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
>
>
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- Re: [Qemu-devel] [PATCH v5 0/7] nvdimm: support MAP_SYNC for memory-backend-file,
Stefan Hajnoczi <=