On Mon, Sep 30, 2024 at 09:37:16AM -0700, Darrick J. Wong wrote: > Ok, so we're only supporting untorn writes if they're exactly the fs > blocksize, and 1 fsblock is between awu_min/max. That simplifies a lot > of things. :) > > Not supporting sub-fsblock atomic writes means that we'll never hit the > directio COW fallback code, which uses the pagecache. > > Not supporting multi-fsblock atomic writes means that you don't have to > figure out how to ensure that we always do cow on forcealign > granularity. Though as I pointed out elsewhere in this thread, that's a > forcealign problem. It does simplify things a lot, and is probably a good idea for the initial version. But I suspect support for atomic writes smaller than the block size will be really useful and we should eventually support them, but maybe now on reflinked files or alwayscow.
