Hello! Sorry i have missed you email for unknown reason to me. It is probably because you answered to email with different subject i sent initially.
> > On Mon, 20 Oct 2025, Uladzislau Rezki (Sony) wrote: > > > When performing a read-modify-write(RMW) operation, any modification > > to a buffered block must cause the entire buffer to be marked dirty. > > > > Marking only a subrange as dirty is incorrect because the underlying > > device block size(ubs) defines the minimum read/write granularity. A > > lower device can perform I/O only on regions which are fully aligned > > and sized to ubs. > > Hi > > I think it would be better to fix this in dm-bufio, so that other dm-bufio > users would also benefit from the fix. Please try this patch - does it fix > it? > If it solves what i describe i do not mind :) > > > From: Mikulas Patocka <[email protected]> > > There may be devices with logical block size larger than 4k. Fix > dm-bufio, so that it will align I/O on logical block size. This commit > fixes I/O errors on the dm-ebs target on the top of emulated nvme device > with 8k logical block size created with qemu parameters: > > -device > nvme,drive=drv0,serial=foo,logical_block_size=8192,physical_block_size=8192 > > Signed-off-by: Mikulas Patocka <[email protected]> > Cc: [email protected] > > --- > drivers/md/dm-bufio.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > Index: linux-2.6/drivers/md/dm-bufio.c > =================================================================== > --- linux-2.6.orig/drivers/md/dm-bufio.c 2025-10-13 21:42:47.000000000 > +0200 > +++ linux-2.6/drivers/md/dm-bufio.c 2025-10-20 14:40:32.000000000 +0200 > @@ -1374,7 +1374,7 @@ static void submit_io(struct dm_buffer * > { > unsigned int n_sectors; > sector_t sector; > - unsigned int offset, end; > + unsigned int offset, end, align; > > b->end_io = end_io; > > @@ -1388,9 +1388,10 @@ static void submit_io(struct dm_buffer * > b->c->write_callback(b); > offset = b->write_start; > end = b->write_end; > - offset &= -DM_BUFIO_WRITE_ALIGN; > - end += DM_BUFIO_WRITE_ALIGN - 1; > - end &= -DM_BUFIO_WRITE_ALIGN; > + align = max(DM_BUFIO_WRITE_ALIGN, > bdev_logical_block_size(b->c->bdev)); > + offset &= -align; > + end += align - 1; > + end &= -align; > if (unlikely(end > b->c->block_size)) > end = b->c->block_size; > > I will check it and get back soon. Thank you. -- Uladzislau Rezki
