On Fri, Jun 07, 2019 at 10:10:17PM +0900, Naohiro Aota wrote: > Sequential allocation is not enough to maintain sequential delivery of > write IOs to the device. Various features (async compress, async checksum, > ...) of btrfs affect ordering of the IOs. This patch introduces submit > buffer to sort WRITE bios belonging to a block group and sort them out > sequentially in increasing block address to achieve sequential write > sequences with __btrfs_map_bio(). > > Signed-off-by: Naohiro Aota <naohiro.aota@xxxxxxx> I hate everything about this. Can't we just use the plugging infrastructure for this and then make sure it re-orders the bios before submitting them? Also what's to prevent the block layer scheduler from re-arranging these io's? Thanks, Josef
