On Fri, Dec 04, 2015 at 09:21:59AM +0800, Qu Wenruo wrote: > > We do have the alignment check in kernel, but it's in the early phase > > where we don't know if nodesize is reliable and print only a warning. > > > This can be enhanced by the following method: At minimum, we can promote the 4k alignment checks in btrfs_check_super_valid from a warning to an error. The blocks must be 4k aligned, regardless of sectorsize or nodesize. > 1) Check sectorsize first > Only several sector size is valid for current btrfs: > 4K, 8K, 16K, 32K, 64K > Just five numbers, quite easy to check. The sectorsize must be PAGE_SIZE at the moment. This will change with Chandan's patchset though. > Or if anyone is going to extend supported sectorsize, we can change > the check to if the number is power of 2 starting from 4K. > > 2) Check nodesize/leafsize then > It should be aligned to sectorsize. This particular check is missing but is implicit because of the sectorsize == PAGE_SIZE restriction. > And nodesize must match with leafsize. > Currently, it's done out of check_super_valid(), we can integrate it. Yeah it's done, then I don't see why we should add it agian. > 3) Check all super root bytenr against *sectorsize* > Yeah, not nodesize. > As some old bad convert will cause metadata extent unaligned to > nodesize(just before my convert rework patch), but only aligned to > sectorsize. > So only check alignment of sectorsize. While the real check should be against the sectorsize, at the moment I think it's covered by the 4k checks anyway. I understand why we can't use the nodesize. So, if we do the warning -> error, we're fine for now. Some of the checks you suggest would be good to merge when the subpage blocksize patchset is merged. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
