savevm: Survive hot-unplug of snapshot device

savevm.c keeps a pointer to the snapshot block device.  If you manage
to get that device deleted, the pointer dangles, and the next snapshot
operation will crash & burn.  Unplugging a guest device that uses it
does the trick:

    $ MALLOC_PERTURB_=234 qemu-system-x86_64 [...]
    QEMU 0.12.50 monitor - type 'help' for more information
    (qemu) info snapshots
    No available block device supports snapshots
    (qemu) drive_add auto if=none,file=tmp.qcow2
    OK
    (qemu) device_add usb-storage,id=foo,drive=none1
    (qemu) info snapshots
    Snapshot devices: none1
    Snapshot list (from none1):
    ID        TAG                 VM SIZE                DATE       VM CLOCK
    (qemu) device_del foo
    (qemu) info snapshots
    Snapshot devices:
    Segmentation fault (core dumped)

Move management of that pointer to block.c, and zap it when the device
it points becomes unusable.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Markus Armbruster 2010-06-25 10:33:39 +02:00 committed by Kevin Wolf
parent 8db520cee8
commit f9092b108f
3 changed files with 31 additions and 27 deletions

View file

@ -193,6 +193,7 @@ const char *bdrv_get_encrypted_filename(BlockDriverState *bs);
void bdrv_get_backing_filename(BlockDriverState *bs,
char *filename, int filename_size);
int bdrv_can_snapshot(BlockDriverState *bs);
BlockDriverState *bdrv_snapshots(void);
int bdrv_snapshot_create(BlockDriverState *bs,
QEMUSnapshotInfo *sn_info);
int bdrv_snapshot_goto(BlockDriverState *bs,