Since commit 9fd3171a, BDRV_O_SNAPSHOT uses an option QDict to specify
the originally requested image as the backing file of the newly created
temporary snapshot. This means that the filename is stored in
"file.filename", which is an option that is not parsed for protocol
names. Therefore things like -drive file=nbd:localhost:10809 were
broken because it looked for a local file with the literal name
'nbd:localhost:10809'.
This patch changes the way BDRV_O_SNAPSHOT works once again. We now open
the originally requested image as normal, and then do a similar
operation as for live snapshots to put the temporary snapshot on top.
This way, both driver specific options and parsed filenames work.
As a nice side effect, this results in code movement to factor
bdrv_append_temp_snapshot() out. This is a good preparation for moving
its call to drive_init() and friends eventually.
Signed-off-by: Kevin Wolf <address@hidden>
---
v2:
- open the backing file for the temporary snapshot read-only from the
beginning so that you can get an r/w block device from a read-only
file using snapshot=on. Gets rid of the bdrv_reopen() whose return
value was ignored in v1, too.
block.c | 148 ++++++++++++++++++++++++---------------------
include/block/block.h | 1 +
tests/qemu-iotests/051 | 8 +++
tests/qemu-iotests/051.out | 28 +++++++++
4 files changed, 115 insertions(+), 70 deletions(-)