On Tue 03-11-15 08:44:24, Dave Chinner wrote: > Realistically, dax_clear_blocks() should probably be implemented at > the pmem driver layer through blkdev_issue_zeroout() because all it > does is directly map the sector/len to pfn via bdev_direct_access() > and then zero it - it's a sector based, block device operation. We > don't actually need a special case path for DAX here. Optimisation > of this operation has little to do with the filesystem. Yep. This is actually what I did in ext4 - the block zeroing is using the ext4 block zeroout path which ends up calling blkdev_issue_zeroout(). I didn't want to special-case DAX and figured out that if we want performance, we should implement blkdev_issue_zeroout() efficiently for pmem. After all ext4 uses blkdev_issue_zeroout() in other extent conversion cases where zeroing out is needed. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
