On Fri, Nov 11, 2022 at 01:07:05PM -0500, Mike Snitzer wrote: > On Thu, Nov 10 2022 at 1:44P -0500, > Keith Busch <kbusch@xxxxxxxx> wrote: > > > From: Keith Busch <kbusch@xxxxxxxxxx> > > > > The 6.0 kernel made some changes to the direct io interface to allow > > offsets in user addresses. This based on the hardware's capabilities > > reported in the request_queue's dma_alignment attribute. > > > > dm-crypt, -log-writes and -integrity require direct io be aligned to the > > block size. Since it was only ever using the default 511 dma mask, this > > requirement may fail if formatted to something larger, like 4k, which > > will result in unexpected behavior with direct-io. > > > > Changes since v1: Added the same fix for -integrity and -log-writes > > > > The first three were reported successfully tested by Dmitrii Tcvetkov, > > but I don't have an official Tested-by: tag. > > > > https://lore.kernel.org/linux-block/20221103194140.06ce3d36@xxxxxxxxxxxxx/T/#mba1d0b13374541cdad3b669ec4257a11301d1860 > > > > Keitio errors on Busch (5): > > block: make dma_alignment a stacking queue_limit > > dm-crypt: provide dma_alignment limit in io_hints > > block: make blk_set_default_limits() private > > dm-integrity: set dma_alignment limit in io_hints > > dm-log-writes: set dma_alignment limit in io_hints > > > > block/blk-core.c | 1 - > > block/blk-settings.c | 9 +++++---- > > block/blk.h | 1 + > > drivers/md/dm-crypt.c | 1 + > > drivers/md/dm-integrity.c | 1 + > > drivers/md/dm-log-writes.c | 1 + > > include/linux/blkdev.h | 16 ++++++++-------- > > 7 files changed, 17 insertions(+), 13 deletions(-) > > > > -- > > 2.30.2 > > > > There are other DM targets that override logical_block_size in their > .io_hints hook (writecache, ebs, zoned). Have you reasoned through why > those do _not_ need updating too? Yeah, that's a good question. The ones that have a problem all make assumptions about a bio's bv_offset being logical block size aligned, and each of those is accounted for here. Everything else looks fine with respect to handling offsets. > Is there any risk of just introducing a finalization method in block > core (that DM's .io_hints would call) that would ensure limits that > are a funtion of another are always in sync? Would avoid whack-a-mole > issues in the future. I don't think we can this particular limit issue. A lot of drivers and devices can use a smaller dma_alignment than the logical block size, so the generic block layer wouldn't really know the driver's intentions for the relationship of these limits.
