On 2013-10-21 22:36, Eric Blake wrote:
On 10/20/2013 07:28 PM, Max Reitz wrote:
Since df2a6f29a5, bdrv_co_do_writev increases the total_sectors value of
a growable block devices on writes after the current end. This leads to
the virtual disk apparently growing in qcow2_save_vmstate, which in turn
affects the disk size captured by the internal snapshot taken directly
afterwards through e.g. the HMP savevm command. Such a "grown" snapshot
cannot be loaded after reopening the qcow2 image, since its disk size
differs from the actual virtual disk size (writing a VM state does not
actually increase the virtual disk size).
Fix this by restoring total_sectors at the end of qcow2_save_vmstate.
Signed-off-by: Max Reitz <mre...@redhat.com>
---
block/qcow2.c | 5 +++++
1 file changed, 5 insertions(+)
@@ -1946,6 +1947,10 @@ static int qcow2_save_vmstate(BlockDriverState *bs,
QEMUIOVector *qiov,
bs->growable = 1;
ret = bdrv_pwritev(bs, qcow2_vm_state_offset(s) + pos, qiov);
bs->growable = growable;
+ // bdrv_co_do_writev will have increased the total_sectors value to include
+ // the VM state - the VM state is however not an actual part of the block
+ // device, therefore, we need to restore the old value.
+ bs->total_sectors = total_sectors;
It looks like // comments aren't forbidden, but also uncommon; I don't
know if /**/ would be better. At any rate:
Ah, right, sorry, I forgot.
Max
