* Max Reitz <mre...@redhat.com> [2017-04-05 15:54:14 +0200]: > On 05.04.2017 11:19, Dong Jia Shi wrote: > > raw_open() expects the caller always passing in the right actual > > @options parameter. But when trying to applying snapshot on a RBD > > image, bdrv_snapshot_goto() calls raw_open() (by calling the > > bdrv_open callback on the BlockDriver) with a NULL @options, and > > that will result in a Segmentation fault. > > > > For the other non-raw format drivers, it also makes sense to passing > > in the actual options, althought they don't trigger the problem so > > far. > > > > Let's prepare a @options by adding the "file" key-value pair to a > > copy of the actual options that were given for the node (i.e. > > bs->options), and pass it to the callback. > > > > BlockDriver.bdrv_open() expects bs->file to be NULL and just > > overwrites it with the result from bdrv_open_child(). That means we > > should actually make sure it's NULL because otherwise the child BDS > > will have a reference count that is 1 too high. So we unconditionally > > invoke bdrv_unref_child() before calling BlockDriver.bdrv_open(), and > > we wrap everything in bdrv_ref()/bdrv_unref() so the BDS isn't > > deleted in the meantime. > > > > Suggested-by: Max Reitz <mre...@redhat.com> > > Signed-off-by: Dong Jia Shi <bjsdj...@linux.vnet.ibm.com> > > --- > > block/snapshot.c | 26 +++++++++++++++++++++++--- > > 1 file changed, 23 insertions(+), 3 deletions(-) > > Thank you, I've applied the patch to my block branch (for inclusion in 2.9): > > https://github.com/XanClic/qemu/commits/block Thank you!
> > Max > -- Dong Jia Shi
