[$] Avoiding blocking file-name lookups

As a general rule, when one attempts to open a file with a system call likeopenat2(),the expectation is that the call will not return until the job is done.But there are times where the desire to open the file is conditional onbeing able to open it immediately, without blocking. Linux has neversupported that mode well, but that may be about to change with thispatch set from Jens Axboe.