migration/block-dirty-bitmap: fix larger granularity bitmaps
authorStefan Reiter <s.reiter@proxmox.com>
Wed, 21 Oct 2020 14:44:56 +0000 (16:44 +0200)
committerEric Blake <eblake@redhat.com>
Mon, 26 Oct 2020 11:55:37 +0000 (06:55 -0500)
commited7b70c27b5c11ff4800e608d301cd7a36b81c5e
tree4785a7ba48aefa565a9a2585fe96c2457db1b517
parent4c5b97bfd0dd54dc27717ae8d1cd10e14eef1430
migration/block-dirty-bitmap: fix larger granularity bitmaps

sectors_per_chunk is a 64 bit integer, but the calculation is done in 32
bits, leading to an overflow for coarse bitmap granularities.

If that results in the value 0, it leads to a hang where no progress is
made but send_bitmap_bits is constantly called with nr_sectors being 0.

Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>
Message-Id: <20201021144456.1072-1-s.reiter@proxmox.com>
Fixes: b35ebdf07 migration: add postcopy migration of dirty bitmaps
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
[eblake: Use correct type for 8ULL, use () to avoid overflow]
Signed-off-by: Eric Blake <eblake@redhat.com>
migration/block-dirty-bitmap.c