On 4/14/24 3:05 AM, Eric Wheeler wrote:
Hello all, I'm not sure if this is a bug or a feature, so thought I'd report it. These are all for Linux 6.6.26: If you start with a 512-byte backing device (logical and physical): # blockdev --getss --getpbsz /dev/nvme9n9 512 512
Hi, this looks wrong. But you should send it to dm-devel list (added to cc) ... Maybe also add lsblk -D (and lsblk -t for block sizes) (where you can see inherited values for all layers). And I see similar problem in dm-crypt with 4k sector but 512B discard granularity (on 6.8.4 - LUKS with forced 4k sector and alllow_discards). What is interesting, for current Linus' tree I see discard granularity 0 (?), but with Mike's DM for-next (with use queue_limits_set fixes) it correctly shows 4k. (Ditto for your integrity case. So perhaps linux-next is fixed.) Milan
then format+open with 4k sectors: # integritysetup format -s 4096 /dev/nvme9n9 # integritysetup open /dev/nvme9n9 integrity-nvme9n9 and find the dm-X device: # ls -l /dev/mapper/integrity-nvme9n9 lrwxrwxrwx. 1 root root 9 Apr 13 17:09 /dev/mapper/integrity-nvme9n9 -> ../dm-189 then check it's discard_granularity, it shows 512: # tail /sys/block/dm-189/queue/discard_* ==> /sys/block/dm-189/queue/discard_granularity <== 512 The sector size is 4k, so supporting unaligned discards seems at least strange, if not invalid, and dmesg complains too: # blockdev --getss /dev/mapper/integrity-nvme9n9 4096 Relatedly, should the physical size of an integrity volume "properly" report 512 to match the backing device, or is 4k correct in this case? Presently it reports 4k: # blockdev --getpbsz /dev/mapper/integrity-nvme2n1 4096 Finally, this is what made me go investiage: when you issue `blkdiscard` on the integrity volume: # blkdiscard /dev/mapper/integrity-nvme9n9 it causes dmesg spews the following: [ 2508.364637] device-mapper: integrity: Bio not aligned on 8 sectors: 0x74ff8000, 0x7f0f [ 2508.364856] device-mapper: integrity: Bio not aligned on 8 sectors: 0x74ffff16, 0xea [ 2508.365070] device-mapper: integrity: Bio not aligned on 8 sectors: 0x757fff0e, 0x7 [ 2508.365973] device-mapper: integrity: Bio not aligned on 8 sectors: 0x757f8000, 0x7f0e What do you think? -- Eric Wheeler
