Signed-off-by: Fam Zheng <f...@redhat.com>
---
block.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/block.c b/block.c
index 1fbbb8d..f5182d8 100644
--- a/block.c
+++ b/block.c
@@ -1722,9 +1722,15 @@ void bdrv_format_default_perms(BlockDriverState *bs,
BdrvChild *c,
}
/* bs->file always needs to be consistent because of the metadata. We
- * can never allow other users to resize or write to it. */
- perm |= BLK_PERM_CONSISTENT_READ;
- shared &= ~(BLK_PERM_WRITE | BLK_PERM_RESIZE);
+ * cannot allow other users to resize or write to it unless the caller
+ * explicitly expects unsafe readings. */
+ if (!(bdrv_get_flags(bs) & BDRV_O_UNSAFE_READ)) {
+ perm |= BLK_PERM_CONSISTENT_READ;
+ shared &= ~(BLK_PERM_WRITE | BLK_PERM_RESIZE);
+ } else {
+ perm &= ~BLK_PERM_CONSISTENT_READ;
+ shared |= BLK_PERM_WRITE | BLK_PERM_RESIZE;
+ }
} else {
/* We want consistent read from backing files if the parent needs it.
* No other operations are performed on backing files. */
--
2.9.3
