On Mon, Apr 22, 2019 at 03:22:55PM -0300, Eduardo Habkost wrote: >On Mon, Apr 22, 2019 at 08:34:51AM -0400, Michael S. Tsirkin wrote: >> On Mon, Apr 22, 2019 at 08:48:47AM +0800, Wei Yang 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. >> > >> > 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) >> >> OK this is in a good shape. As we are in freeze anyway, >> there's still a bit more time to polish it. I have a couple of >> suggestions: >> >> - squash docs in same patch with code, no need for two patches >> - mmap errors are not silently ignored as the doc says, >> a warning is produced > >Note that a warning is produced only if both share=on and pmem=on >is specified. If using pmem=on without share=on, no warning is >printed at all. > >I agree we could squash the docs in the same patch, but I don't >want to prevent the code from being merged and require v15 to be >sent just because we are still polishing the documentation. > >If there are no objections, I plan to apply this version of the >series including the following fixup (just removing the word >"silently"), and I suggest further improvements to be sent as >follow up patches. >
If my understanding is correct, the following up patch is: "send the warnings to an errp object and not stderr" -- Wei Yang Help you, Help me