block: Allow reopen rw without BDRV_O_ALLOW_RDWR
BDRV_O_ALLOW_RDWR is a flag that tells whether qemu can internally
reopen a node read-write temporarily because the user requested
read-write for the top-level image, but qemu decided that read-only is
enough for this node (a backing file).
bdrv_reopen() is different, it is also used for cases where the user
changed their mind and wants to update the options. There is no reason
to forbid making a node read-write in that case.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
diff --git a/block.c b/block.c
index ab908cd..2711c3d 100644
--- a/block.c
+++ b/block.c
@@ -246,7 +246,8 @@
return !bdrv_is_read_only(bs) && !(bs->open_flags & BDRV_O_INACTIVE);
}
-int bdrv_can_set_read_only(BlockDriverState *bs, bool read_only, Error **errp)
+int bdrv_can_set_read_only(BlockDriverState *bs, bool read_only,
+ bool ignore_allow_rdw, Error **errp)
{
/* Do not set read_only if copy_on_read is enabled */
if (bs->copy_on_read && read_only) {
@@ -256,7 +257,9 @@
}
/* Do not clear read_only if it is prohibited */
- if (!read_only && !(bs->open_flags & BDRV_O_ALLOW_RDWR)) {
+ if (!read_only && !(bs->open_flags & BDRV_O_ALLOW_RDWR) &&
+ !ignore_allow_rdw)
+ {
error_setg(errp, "Node '%s' is read only",
bdrv_get_device_or_node_name(bs));
return -EPERM;
@@ -269,7 +272,7 @@
{
int ret = 0;
- ret = bdrv_can_set_read_only(bs, read_only, errp);
+ ret = bdrv_can_set_read_only(bs, read_only, false, errp);
if (ret < 0) {
return ret;
}
@@ -2907,7 +2910,7 @@
* to r/w. Attempting to set to r/w may fail if either BDRV_O_ALLOW_RDWR is
* not set, or if the BDS still has copy_on_read enabled */
read_only = !(reopen_state->flags & BDRV_O_RDWR);
- ret = bdrv_can_set_read_only(reopen_state->bs, read_only, &local_err);
+ ret = bdrv_can_set_read_only(reopen_state->bs, read_only, true, &local_err);
if (local_err) {
error_propagate(errp, local_err);
goto error;