stream_complete() skips the work of rewriting the backing file if
the job was cancelled, if data->reached_end is false, or if there
was an error detected (non-zero data->ret) during the streaming.
But note that in stream_run(), data->reached_end is only set if the
loop ran to completion, and data->ret is only 0 in two cases:
either the loop ran to completion (possibly by cancellation, but
stream_complete checks for that), or we took an early goto out
because there is no bs->backing. Thus, we can preserve the same
semantics without the use of reached_end, by merely checking for
bs->backing (and logically, if there was no backing file, streaming
is a no-op, so there is no backing file to rewrite).
Suggested-by: Kevin Wolf <kw...@redhat.com>
Signed-off-by: Eric Blake <ebl...@redhat.com>
---
v4: new patch
---
block/stream.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/block/stream.c b/block/stream.c
index 746d525..12f1659 100644
--- a/block/stream.c
+++ b/block/stream.c
@@ -59,7 +59,6 @@ static int coroutine_fn stream_populate(BlockBackend *blk,
typedef struct {
int ret;
- bool reached_end;
} StreamCompleteData;
static void stream_complete(BlockJob *job, void *opaque)
@@ -70,7 +69,7 @@ static void stream_complete(BlockJob *job, void *opaque)
BlockDriverState *base = s->base;
Error *local_err = NULL;
- if (!block_job_is_cancelled(&s->common) && data->reached_end &&
+ if (!block_job_is_cancelled(&s->common) && bs->backing &&
data->ret == 0) {
const char *base_id = NULL, *base_fmt = NULL;
if (base) {
@@ -211,7 +210,6 @@ out:
/* Modify backing chain and close BDSes in main loop */
data = g_malloc(sizeof(*data));
data->ret = ret;
- data->reached_end = sector_num == end;
block_job_defer_to_main_loop(&s->common, stream_complete, data);
}
--
2.9.4
