On Wed, Dec 20, 2023 at 05:27:14PM -0800, Song Liu wrote: > Upper layer (fs, etc.) may issue flush with something like: > > bio_reset(bio, bdev, REQ_OP_FLUSH); > bio->bi_end_io = xxx; > submit_bio(bio); No, they can't. REQ_OP_FLUSH is currently only used by request based drivers and only generated by the flush state machine. (Not that I particularly like this wart, I'd much prefer file systems to submit a REQ_OP_FLUSH than an empty write with a preflush flag, but that's not a trivial change).
