@@ -1516,6 +1516,12 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options,
goto free_exit;
}
+ if (reference || qdict_size(options)) {
+ /* TODO: Should only be set to true if @options contains actually
+ * significant runtime options */
+ bs->backing_overridden = true;
+ }
+
if (bs->backing_format[0] != '\0' && !qdict_haskey(options, "driver")) {
qdict_put(options, "driver", qstring_from_str(bs->backing_format));
}
@@ -1659,6 +1665,9 @@ static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs,
bdrv_ref(bs_snapshot);
bdrv_append(bs_snapshot, bs);
+ bs_snapshot->backing_overridden = true;
+ bdrv_refresh_filename(bs_snapshot);
+
g_free(tmp_filename);
return bs_snapshot;
@@ -1786,6 +1795,7 @@ static BlockDriverState *bdrv_open_inherit(const char *filename,
backing = qdict_get_try_str(options, "backing");
if (backing && *backing == '\0') {
flags |= BDRV_O_NO_BACKING;
+ bs->backing_overridden = true;
qdict_del(options, "backing");
}
@@ -3959,6 +3969,10 @@ void bdrv_refresh_filename(BlockDriverState *bs)
* refresh those first */
QLIST_FOREACH(child, &bs->children, next) {
bdrv_refresh_filename(child->bs);
+
+ if (child->role == &child_backing && child->bs->backing_overridden) {
+ bs->backing_overridden = true;
+ }
}
if (drv->bdrv_refresh_filename) {
@@ -891,6 +891,10 @@ static void mirror_complete(BlockJob *job, Error **errp)
assert(!target->backing);
bdrv_set_backing_hd(target, backing);
+
+ /* The target image's file already has been created with the backing
+ * file we just set, so there is no need to set backing_overridden or
+ * call bdrv_refresh_filename(). */
}
s->should_complete = true;
@@ -1771,6 +1771,8 @@ static void external_snapshot_commit(BlkActionState *common)
{
ExternalSnapshotState *state =
DO_UPCAST(ExternalSnapshotState, common, common);
+ TransactionAction *action = common->action;
+ bool image_was_existing = false;
bdrv_set_aio_context(state->new_bs, state->aio_context);
@@ -1783,6 +1785,20 @@ static void external_snapshot_commit(BlkActionState *common)
bdrv_reopen(state->old_bs, state->old_bs->open_flags & ~BDRV_O_RDWR,
NULL);
}
+
+ if (action->type == TRANSACTION_ACTION_KIND_BLOCKDEV_SNAPSHOT_SYNC) {
+ BlockdevSnapshotSync *s = action->u.blockdev_snapshot_sync.data;
+ if (s->has_mode && s->mode == NEW_IMAGE_MODE_EXISTING) {
+ image_was_existing = true;
+ }
+ } else {
+ image_was_existing = true;
+ }
+
+ if (image_was_existing) {
+ state->new_bs->backing_overridden = true;
+ bdrv_refresh_filename(state->new_bs);
+ }
}
static void external_snapshot_abort(BlkActionState *common)
@@ -461,6 +461,7 @@ struct BlockDriverState {
char backing_file[PATH_MAX]; /* if non zero, the image is a diff of
this file image */
char backing_format[16]; /* if non-zero and backing_file exists */
+ bool backing_overridden; /* backing file has been specified by the user */
QDict *full_open_options;
char exact_filename[PATH_MAX];
If the backing file is overridden, this most probably does change the guest-visible data of a BDS. Therefore, we will need to consider this in bdrv_refresh_filename(). Adding a new field to the BDS is not nice, but it is very simple and exactly keeps track of whether the backing file has been overridden. Signed-off-by: Max Reitz <mreitz@redhat.com> --- While this patch adds a TODO comment that sounds like it could be resolved in a later patch in this series, it is not. Checking whether @options contains significant runtime options is not trivial, because we not only care about significant options at that level but also at levels below: Normally, it should be fine to check that for backing_hd and backing_hd->file->bs, but that's not for sure. So I decided a false positive is better than a false negative here, which is why the TODO persists throughout the series. --- block.c | 14 ++++++++++++++ block/mirror.c | 4 ++++ blockdev.c | 16 ++++++++++++++++ include/block/block_int.h | 1 + 4 files changed, 35 insertions(+)