On Fri, Oct 30, 2026 at 12:08:24PM +0100, Denis V. Lunev wrote: > On 8/12/26 14:14, Denis V. Lunev wrote: > > qom-set of the 'drive' property is allowed on a realized device and ends > > up in bdrv_replace_child_bs(), which swaps the node a BdrvChild points to > > without telling the parent anything about it. Every other way the size of > > a node changes goes through bdrv_co_truncate(), which does notify, so a > > device model caching the size of its child has no way to learn that it > > changed. > > > > scsi-disk is the one really hurt by this. check_lba_range() validates > > every guest request against SCSIDevice.max_lba, filled in by > > scsi_disk_reset() and updated only by the READ CAPACITY(10) and (16) > > handlers. Point a scsi-hd at a larger node and every request past the end > > of the old one is refused with ILLEGAL REQUEST / LOGICAL BLOCK ADDRESS > > OUT OF RANGE for the whole life of the device, which Linux turns into > > EREMOTEIO for reads as well as writes. It is silent on the host: > > out-of-range requests are answered by scsi_check_condition() and never > > reach scsi_handle_rw_error(), so there is no BLOCK_IO_ERROR event and > > io-status stays 'ok'. virtio-blk and ide call blk_get_geometry() for > > every request, so they end up with a stale idea of the size but never > > refuse I/O the node underneath can serve. > > > > Signed-off-by: Denis V. Lunev <[email protected]> > > Cc: Kevin Wolf <[email protected]> > > Cc: Hanna Reitz <[email protected]> > > Cc: Paolo Bonzini <[email protected]> > > Cc: Fam Zheng <[email protected]> > > > > Denis V. Lunev (4): > > block: notify the parent when a replaced child has a different size > > scsi-disk: refresh the cached capacity from the resize callback > > tests/qtest/virtio-scsi: cover a replacement that changes the size > > tests/qemu-iotests/qom-set-drive: replace with a differently sized > > node > > > > block.c | 13 +++++ > > hw/scsi/scsi-disk.c | 16 ++++-- > > include/block/block_int-io.h | 3 ++ > > tests/qemu-iotests/tests/qom-set-drive | 14 +++-- > > tests/qemu-iotests/tests/qom-set-drive.out | 2 + > > tests/qtest/virtio-scsi-test.c | 63 ++++++++++++++++++++++ > > 6 files changed, 104 insertions(+), 7 deletions(-) > > > > > > base-commit: 3e3ccab106f879b1512f8e0d51a827dd4de30e22 > ping
Looks like this one has sat for a while; while it is not directly related to my usual NBD pulls, I'm in the middle of preparing a block layer pull request today so I'll add this one in my queue if it passes my testing. -- Eric Blake, Principal Software Engineer Red Hat, Inc. Virtualization: qemu.org | libguestfs.org
