On Tue, Jun 28, 2022 at 11:18:34PM -0400, Eric Farman wrote:

Sort of. In the working case, I see a set of iovecs come through with
different counts:

base	count
0000	0001
0000	0200
0000	0400
0000	0800
0000	1000
0001	1000
0200	1000 << Change occurs here
0400	1000
0800	1000
1000	1000

EINVAL was being returned for any of these iovecs except the page-
aligned ones. Once the x200 request returns 0, the remainder of the
above list was skipped and the requests continue elsewhere on the file.

Still not sure how our request is getting us into this process. We're
simply asking to read a single block, but that's somewhere within an
image file.

I thought this was sounding like some kind of corruption. I tested ext4 on
various qemu devices with 4k logical block sizes, and it all looks okay there.

What block driver are you observing this with?