restic/vendor/bazil.org/fuse/doc/mount-sequence.md
2017-07-23 14:25:38 +02:00

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The mount sequence

FUSE mounting is a little bit tricky. There's a userspace helper tool that performs the handshake with the kernel, and then steps out of the way. This helper behaves differently on different platforms, forcing a more complex API on us.

Successful runs

On Linux, the mount is immediate and file system accesses wait until the requests are served.

Diagram of Linux FUSE mount sequence

On OS X, the mount becomes visible only after InitRequest (and maybe more) have been served.

Diagram of OSXFUSE mount sequence

Errors

Let's see what happens if InitRequest gets an error response. On Linux, the mountpoint is there but all operations will fail:

Diagram of Linux error handling

On OS X, the mount never happened:

Diagram of OS X error handling