On Fri, Jun 05, 2015 at 05:19:18PM -0400, Dan Williams wrote: > None of the implementations currently use it. The common > bdev_direct_access() entry point handles all the size checks before > calling ->direct_access(). Interesting. The reason it was still there, even after moving all the size checks to bdev_direct_access() was to support the case of a hypothetical future driver that exposed several discontiguous ranges as a single block device. But we don't actually need it for that, as long as the discontiguous ranges are relatively large. As the comment you deleted noted, the brd driver could do this, but I certainly haven't taken the time to figure out whether it'd be a performance win if the pages "just happen" to line up right. So I don't think I'm objecting to this patch (except that it conflicts textually with my dynamic mapping patch that you've seen but hasn't been posted publically yet). Just something to think about. -- 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
