| Message ID | 20231201142520.32255-2-kwolf@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | block: Make snapshots fail gracefully on inactive images | expand |
diff --git a/block/snapshot.c b/block/snapshot.c index ec8cf4810b..c4d40e80dd 100644 --- a/block/snapshot.c +++ b/block/snapshot.c @@ -196,8 +196,10 @@ bdrv_snapshot_fallback(BlockDriverState *bs) int bdrv_can_snapshot(BlockDriverState *bs) { BlockDriver *drv = bs->drv; + GLOBAL_STATE_CODE(); - if (!drv || !bdrv_is_inserted(bs) || bdrv_is_read_only(bs)) { + + if (!drv || !bdrv_is_inserted(bs) || !bdrv_is_writable(bs)) { return 0; }
bdrv_is_read_only() only checks if the node is configured to be read-only eventually, but even if it returns false, writing to the node may not be permitted at the moment (because it's inactive). bdrv_is_writable() checks that the node can be written to right now, and this is what the snapshot operations really need. Change bdrv_can_snapshot() to use bdrv_is_writable() to fix crashes like the following: $ ./qemu-system-x86_64 -hda /tmp/test.qcow2 -loadvm foo -incoming defer qemu-system-x86_64: ../block/io.c:1990: int bdrv_co_write_req_prepare(BdrvChild *, int64_t, int64_t, BdrvTrackedRequest *, int): Assertion `!(bs->open_flags & BDRV_O_INACTIVE)' failed. The resulting error message after this patch isn't perfect yet, but at least it doesn't crash any more: $ ./qemu-system-x86_64 -hda /tmp/test.qcow2 -loadvm foo -incoming defer qemu-system-x86_64: Device 'ide0-hd0' is writable but does not support snapshots Signed-off-by: Kevin Wolf <kwolf@redhat.com> --- block/snapshot.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)