Hi, I happened to notice the following QEMU bug report: https://gitlab.com/qemu-project/qemu/-/issues/1290 I believe it's a regression from the following kernel commit: commit b1a000d3b8ec582da64bb644be633e5a0beffcbf Author: Keith Busch <kbusch@xxxxxxxxxx> Date: Fri Jun 10 12:58:29 2022 -0700 block: relax direct io memory alignment The bug is that if a dm-crypt device is set up with a crypto sector size (and thus also a logical_block_size) of 4096, then the block layer now lets through direct I/O requests to dm-crypt when the user buffer has only 512-byte alignment, instead of the 4096-bytes expected by dm-crypt in that case. This is because the dma_alignment of the device-mapper device is only 511 bytes. This has two effects in this case: - The error code for DIO with a misaligned buffer is now EIO, instead of EINVAL as expected and documented. This is because the I/O reaches dm-crypt instead of being rejected by the block layer. - STATX_DIOALIGN reports 512 bytes for stx_dio_mem_align, instead of the correct value of 4096. (Technically not a regression since STATX_DIOALIGN is new in v6.1, but still a bug.) Any thoughts on what the correct fix is here? Maybe the device-mapper layer needs to set dma_alignment correctly? Or maybe the block layer needs to set it to 'logical_block_size - 1' by default? - Eric
