block/copy-before-write: relax permission requirements when no parents
We are going to publish copy-before-write filter. So, user should be
able to create it with blockdev-add first, specifying both filtered and
target children. And then do blockdev-reopen, to actually insert the
filter where needed.
Currently, filter unshares write permission unconditionally on source
node. It's good, but it will not allow to do blockdev-add. So, let's
relax restrictions when filter doesn't have any parent.
Test output is modified, as now permission conflict happens only when
job creates a blk parent for filter node.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210824083856.17408-11-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
diff --git a/block/copy-before-write.c b/block/copy-before-write.c
index a7996d5..2a51cc6 100644
--- a/block/copy-before-write.c
+++ b/block/copy-before-write.c
@@ -142,10 +142,12 @@
bdrv_default_perms(bs, c, role, reopen_queue,
perm, shared, nperm, nshared);
- if (perm & BLK_PERM_WRITE) {
- *nperm = *nperm | BLK_PERM_CONSISTENT_READ;
+ if (!QLIST_EMPTY(&bs->parents)) {
+ if (perm & BLK_PERM_WRITE) {
+ *nperm = *nperm | BLK_PERM_CONSISTENT_READ;
+ }
+ *nshared &= ~(BLK_PERM_WRITE | BLK_PERM_RESIZE);
}
- *nshared &= ~(BLK_PERM_WRITE | BLK_PERM_RESIZE);
}
}
