Re: [Qemu-devel] [PATCH V13 4/5] util/mmap-alloc: support MAP_SYNC in qemu_ram_mmap()

[Wei Yang <richardw.yang@linux.intel.com>]

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.

-- 
Wei Yang
Help you, Help me