[$] Atomic writes without tears

John Garry and Ted Ts'o led a discussion about supporting atomic writes for bufferedI/O, without any torn (or partial) writes to the device, at the 2024 Linux Storage,Filesystem, Memory Management, and BPF Summit. It is something of acontinuation of a discussion at last year'ssummit. The goal is to help PostgreSQL, which writes its data using16KB buffered I/O; it currently has to do a lot of extra work to ensurethat its data is safe on disk. A promise of non-torn, 16KB buffered writeswould allow the database to avoid doing double writes.