[PATCH 2/7] stream: exclude a link to filter from freezing

[Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>]

A node above the base can be the filter of the concurrent job. In that
case, the filter cannot be removed being a part of the frozen chain.
Exclude the link to filter node from freezing and provide the safety
check for a concurrent job.

Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
---
 block/stream.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/block/stream.c b/block/stream.c
index bd4a351..d8b4bbe 100644
--- a/block/stream.c
+++ b/block/stream.c
@@ -244,7 +244,7 @@ void stream_start(const char *job_id, BlockDriverState *bs,
          above_base = bdrv_filtered_bs(above_base))
     {}
 
-    if (bdrv_freeze_chain(bs, above_base, errp) < 0) {
+    if (bdrv_freeze_chain(bs, bottom_cow_node, errp) < 0) {
         return;
     }
 
@@ -257,6 +257,15 @@ void stream_start(const char *job_id, BlockDriverState *bs,
         }
     }
 
+    /*
+     * Check for an overlapping block-commit job that is not allowed.
+     */
+    if (bdrv_freeze_chain(bottom_cow_node, above_base, errp) < 0) {
+        goto fail;
+    } else {
+        bdrv_unfreeze_chain(bottom_cow_node, above_base);
+    }
+
     /* Prevent concurrent jobs trying to modify the graph structure here, we
      * already have our own plans. Also don't allow resize as the image size is
      * queried only at the job start and then cached. */
@@ -276,7 +285,8 @@ void stream_start(const char *job_id, BlockDriverState *bs,
      * bdrv_reopen_set_read_only() due to parallel block jobs running.
      */
     base = bdrv_filtered_bs(above_base);
-    for (iter = bdrv_filtered_bs(bs); iter && iter != base;
+    for (iter = bdrv_filtered_bs(bs);
+         iter && iter != base && iter->drv && !iter->drv->is_filter;
          iter = bdrv_filtered_bs(iter))
     {
         block_job_add_bdrv(&s->common, "intermediate node", iter, 0,
@@ -298,5 +308,5 @@ fail:
     if (bs_read_only) {
         bdrv_reopen_set_read_only(bs, true, NULL);
     }
-    bdrv_unfreeze_chain(bs, above_base);
+    bdrv_unfreeze_chain(bs, bottom_cow_node);
 }
-- 
1.8.3.1