Hi,
As presented in [1] there is a bug in the zone code in raw_co_prw(),
specifically we don’t check whether there actually is zone information
before running code that assumes there is (and thus we run into a
division by zero). This has now also been reported in [2].
I believe the solution [1] is incomplete, though, which is why I’m
sending this separate series: I don’t think checking bs->wps and/or
bs->bl.zone_size to determine whether there is zone information is
right; for example, we do not have raw_refresh_zoned_limits() clear
those values if on a refresh, zone information were to disappear.
It is also weird that we separate checking bs->wps and bs->bl.zone_size
at all; raw_refresh_zoned_limits() seems to intend to ensure that either
we have information with non-NULL bs->wps and non-zero bs->bl.zone_size,
or we don’t.
I think we should have a single flag that tells whether we have valid
information or not, and it looks to me like bs->bl.zoned != BLK_Z_NONE
is the condition that fits best.
Patch 1 ensures that raw_refresh_zoned_limits() will set bs->bl.zoned to
BLK_Z_NONE on error, so that we can actually be sure that this condition
tells us whether we have valid information or not.
Patch 2 unifies all conditional checks for zone information to use
bs->bl.zoned != BLK_Z_NONE.
Patch 3 is the I/O error path fix, which is not really different from
[1].
Patch 4 does a bit of clean-up.
Patch 5 adds a regression test.
[1] https://lists.nongnu.org/archive/html/qemu-devel/2023-06/msg01742.html
[2] https://bugzilla.redhat.com/show_bug.cgi?id=2234374