[$] Cloud-storage optimizations

"I/O hints" for storage devices, which are meant to improve performance bygiving the devices extra information about the nature of the I/O, have a long history withLinux. But the codefor write hints was "ripped out last year", according to a message from TedTs'o proposing a discussion about new optimizations for cloud-storage devices.That discussion took place in acombined storage and filesystem session at the2023 Linux Storage, Filesystem,Memory-Management and BPF Summit. In it, Ts'o proposed that the Linuxcommunity define its own set of hints rather than just following along with thehints in the standards-which have largely been ignored by the vendors inany case.