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Also, this method was the last remaining part of our `tar-rs` fork, so we can switch to the upstream version now.
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timvisee
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Jan 8, 2026
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Simple and effective, brilliant!
I like that we can now use upstream tar-rs.
generall
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Feb 9, 2026
* Remove call to Archive::set_sync Also, this method was the last remaining part of our `tar-rs` fork, so we can switch to the upstream version now. * Do syncfs
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Problem
Restoring snapshot that contains a lot of small files takes a lot of time.
This happen because we set
tar::Archive::set_sync(from our tar-rs fork) that callsfsyncon every file in a sequence. Fsyncing each file individually is slow.Solution
Disable
set_syncand usesyncfsinstead.syncfssyncs the whole filesystem at once, not just a particular single file.A potential drawback is that background writes (outside of snapshot restore code) can slow
syncfsdown, but I think it's a worthy tradeoff.Also, since
set_syncwas the last thing from ourtar-rsfork, we can switch to the upstreamtar-rs.Alternatives & synthetic benchmarks
I've considered the
fsyncin sequence (baseline).sync_file_rangein sequence thenfsyncin sequence.sync_file_rangeacts as a hint for the kernel to schedule flushing. It is non-blocking.fsyncacts as a barrier until the scheduled flush is done.syncfson a single file.io_uring: callfsyncthroughio_uringpipeline.Results and code: https://gist.github.com/xzfc/b22591fa5a5a192a1574857b00d7cb8d#file-results-md