feat: extend io_uring perm check to find EINVAL

[doyleish]

The io_uring_setup syscall may fail with EINVAL when called with the IORING_SETUP_SINGLE_ISSUER flag bit before support for that flag was added (linux 6.0). This would help the user deduce quickly that a kernel upgrade is required.

[rphmeier]

Thanks for the additional detection!

Unfortunately, this is a breaking change in the public API (all users matching on the IoUringPermission would have their code break after adding this additional variant)

How about we still return "Denied", but print a detailed warning message?

[rphmeier]

(I pushed a commit which returns NotSupported and prints an error containing the text you provided. Thanks for investigating and upstreaming the fix)

[graphite-app]

The multiline string literal includes all leading whitespace from the source code indentation. This will print with awkward indentation in the output.

The message will be displayed as:

(blank line)
                The device has permission...
                for io_uring_setup...
                ...

Fix by removing indentation inside the string:

println!("The device has permission to use io_uring, but does not support the flags required \
for io_uring_setup. NOMT uses the IORING_SETUP_SINGLE_ISSUER flag for io_uring which \
was introduced in linux 6.0. Please update your kernel to at least version 6.0 \
to use NOMT with io_uring.");

Or use eprintln! for error messages instead of println!.

Spotted by Graphite Agent



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