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Re: [Qemu-devel] [PATCH V7 0/6] nvdimm: support MAP_SYNC for memory-back
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [PATCH V7 0/6] nvdimm: support MAP_SYNC for memory-backend-file |
Date: |
Tue, 18 Dec 2018 09:18:02 +0000 |
User-agent: |
Mutt/1.10.1 (2018-07-13) |
On Tue, Dec 18, 2018 at 04:16:44PM +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' or 'pmem=off', QEMU will abort
> - off: never pass MAP_SYNC to mmap(2)
> - auto (default): if MAP_SYNC is supported and 'share=on' 'pmem=on', work as
> if
> 'sync=on'; otherwise, work as if 'sync=off'
I took a quick look and didn't see human-readable errors when pmem=off.
Is it possible to report it instead of aborting?
Thanks,
Stefan
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- Re: [Qemu-devel] [PATCH V7 6/6] hostmem-file: add 'sync' option, (continued)
- Re: [Qemu-devel] [PATCH V7 6/6] hostmem-file: add 'sync' option, Michael S. Tsirkin, 2018/12/18
- Re: [Qemu-devel] [PATCH V7 6/6] hostmem-file: add 'sync' option, Yi Zhang, 2018/12/19
- Re: [Qemu-devel] [PATCH V7 6/6] hostmem-file: add 'sync' option, Michael S. Tsirkin, 2018/12/19
- Re: [Qemu-devel] [PATCH V7 6/6] hostmem-file: add 'sync' option, Yi Zhang, 2018/12/19
- Re: [Qemu-devel] [PATCH V7 6/6] hostmem-file: add 'sync' option, Michael S. Tsirkin, 2018/12/19
- Re: [Qemu-devel] [PATCH V7 6/6] hostmem-file: add 'sync' option, Yi Zhang, 2018/12/20
- Re: [Qemu-devel] [PATCH V7 6/6] hostmem-file: add 'sync' option, Michael S. Tsirkin, 2018/12/20
- Re: [Qemu-devel] [PATCH V7 6/6] hostmem-file: add 'sync' option, Yi Zhang, 2018/12/20
- Re: [Qemu-devel] [PATCH V7 6/6] hostmem-file: add 'sync' option, Michael S. Tsirkin, 2018/12/21
- Re: [Qemu-devel] [PATCH V7 6/6] hostmem-file: add 'sync' option, Yi Zhang, 2018/12/24
Re: [Qemu-devel] [PATCH V7 0/6] nvdimm: support MAP_SYNC for memory-backend-file,
Stefan Hajnoczi <=