[$] Cloud-storage optimizations

'I/O hints' for storage devices, which are meant to improve performance by
giving the devices
extra information about the nature of the I/O, have a long history with
Linux.
But the code
for write hints was 'ripped out last year', according to a message from Ted
Ts'o proposing a discussion about new optimizations for cloud-storage devices.
That discussion took place in a
combined storage and filesystem session at the
2023 Linux Storage, Filesystem,
Memory-Management and BPF Summit. In it, Ts'o proposed that the Linux
community define its own set of hints rather than just following along with the
hints in the standards—which have largely been ignored by the vendors in
any case.