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-rw-r--r--block.c2
-rw-r--r--block/vvfat.c22
-rw-r--r--include/block/block_int.h1
3 files changed, 24 insertions, 1 deletions
diff --git a/block.c b/block.c
index d67819f2a2..281ce7bec3 100644
--- a/block.c
+++ b/block.c
@@ -823,7 +823,7 @@ static void bdrv_backing_options(int *child_flags, QDict *child_options,
*child_flags = flags;
}
-static const BdrvChildRole child_backing = {
+const BdrvChildRole child_backing = {
.inherit_options = bdrv_backing_options,
.drained_begin = bdrv_child_cb_drained_begin,
.drained_end = bdrv_child_cb_drained_end,
diff --git a/block/vvfat.c b/block/vvfat.c
index 7f230be006..72b482cb1f 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -3052,6 +3052,27 @@ err:
return ret;
}
+static void vvfat_child_perm(BlockDriverState *bs, BdrvChild *c,
+ const BdrvChildRole *role,
+ uint64_t perm, uint64_t shared,
+ uint64_t *nperm, uint64_t *nshared)
+{
+ BDRVVVFATState *s = bs->opaque;
+
+ assert(c == s->qcow || role == &child_backing);
+
+ if (c == s->qcow) {
+ /* This is a private node, nobody should try to attach to it */
+ *nperm = BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE;
+ *nshared = BLK_PERM_WRITE_UNCHANGED;
+ } else {
+ /* The backing file is there so 'commit' can use it. vvfat doesn't
+ * access it in any way. */
+ *nperm = 0;
+ *nshared = BLK_PERM_ALL;
+ }
+}
+
static void vvfat_close(BlockDriverState *bs)
{
BDRVVVFATState *s = bs->opaque;
@@ -3077,6 +3098,7 @@ static BlockDriver bdrv_vvfat = {
.bdrv_file_open = vvfat_open,
.bdrv_refresh_limits = vvfat_refresh_limits,
.bdrv_close = vvfat_close,
+ .bdrv_child_perm = vvfat_child_perm,
.bdrv_co_preadv = vvfat_co_preadv,
.bdrv_co_pwritev = vvfat_co_pwritev,
diff --git a/include/block/block_int.h b/include/block/block_int.h
index eb0598e580..63d54460e5 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -466,6 +466,7 @@ struct BdrvChildRole {
extern const BdrvChildRole child_file;
extern const BdrvChildRole child_format;
+extern const BdrvChildRole child_backing;
struct BdrvChild {
BlockDriverState *bs;