fs: don't poison File when blocking op is cancelled - #8291
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Previously, running certain tokio::fs::File ops (read, seek, etc) after the backing blocking task was cancelled (e.g. due to a runtime shutdown) would lead to the second operation panicking, instead of erroring out gracefully. This is due to the ops returing via `?` without resetting their internal state into a valid one.
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ADD-SP
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Darksonn
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It looks ok to me, but it looks like @ADD-SP also wants to review. |
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Thanks for the merge! |
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Motivation
tokio::fs::Filetracks its blocking ops with anIdle -> Busy -> Idlestate machine. When a blocking task is cancelled (e.g. on runtime shutdown) or fails to spawn, the error path returns mid-transition and leaves an invalid state, so the next op panics.Affects
read/write/seek/flush/set_len.Found in the wild as a flaky
JoinHandle polled after completioncrash in Wasmer, which was tearing down a tokio runtime while host-file I/O was still in flight.Solution
Reset to a valid
Idlestate before returning the error. Only error branches are touched, success/Pendingpaths are unchanged.Adds a regression test.