On Wed, Aug 25, 2021 at 10:50 PM Christoph Hellwig <hch@xxxxxx> wrote: > > On Wed, Aug 25, 2021 at 05:49:45PM -0700, Neeraj Singh wrote: > > One conclusion from reviewing that thread is that as of then, > > sync_file_ranges isn't actually enough > > to make a hard guarantee about writeout occurring. See > > https://lore.kernel.org/linux-fsdevel/20190319204330.GY26298@dastard/. > > My hope is that the Linux FS developers have rectified that shortcoming by now. > > I'm not sure what shortcoming you mean. sync_file_ranges is a system > call that only causes data writeback. It never performs metadata write > back and thus is not an integrity operation at all. That is also very > clearly documented in the man page. > You're right. On re-read of the man page, sync_file_range is listed as an "extremely dangerous" system call. The opportunity in the linux kernel is to offer an alternative set of flags or separate API that allows for an application like Git to separate a metadata writeback request from the disk flush. Separately, I'm hoping I can push from the Windows filesystem side to get a barrier primitive put into the NVME standard so that we can offer more useful behavior to applications rather than these painful hardware flushes.
