Am 14.12.2016 um 18:07 schrieb Christoph Hellwig: >> To prevent partitions that are not aligned to the physical blocksize >> > of a device check for the alignment in the blkpg_ioctl. > We'd also need to reject this when reading partitions from disk, right? > I am not sure if there is a problem. I was not able to recreate the error with a partition read from disk. But simply because I was not able to write a defective partition table to disk. All variants I tried where OK. So I am at least not aware of a way to break it via the partition detection code. I just noticed that the ioctl which can be called by anyone is able to establish defective partitions. Am 15.12.2016 um 09:56 schrieb Damien Le Moal: > On 12/15/16 17:45, Christoph Hellwig wrote: >> On Thu, Dec 15, 2016 at 10:33:47AM +0900, Damien Le Moal wrote: >>> For a regular block device, I agree. But in Stephan case, I think that >>> the check really needs to be against the physical block size, with the >>> added condition that the bdev is a DASD device (similarly to the zone >>> alignment check for zoned block devices). >> >> Then they need to expose a chunk_size. physical block size is defined >> as not having a meaning for the kernel. > > Or create the block device with the logical block size set to the > physical sector size. Which would be even more simple and in fact > correct in this case since only physically aligned accesses make sense > for DASD. > We already do it this way. So the logical blocksize is fine for DASD. I just was not aware of the fact that the physical blocksize is a best_can_do field. So I changed it this way and also incorporated your other feedback regarding the modulo. Here is the second suggestion for the patch. Stefan Haberland (1): block: check partition alignment block/ioctl.c | 3 +++ 1 file changed, 3 insertions(+) -- 2.8.4 -- To unsubscribe from this list: send the line "unsubscribe linux-block" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
