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 Max
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