stream: Allow users to request only format driver names in backing file format

[mirror_qemu.git] / block / stream.c

diff --git a/block/stream.c b/block/stream.c
index 5323a9976df71ef833167bcd8704541e81be2dd7..7031eef12b63494df345bf4c7b6ec276ba359328 100644 (file)
--- a/block/stream.c
+++ b/block/stream.c
@@ -39,6 +39,7 @@ typedef struct StreamBlockJob {
     BlockDriverState *target_bs;
     BlockdevOnError on_error;
     char *backing_file_str;
+    bool backing_mask_protocol;
     bool bs_read_only;
 } StreamBlockJob;
 
@@ -90,16 +91,23 @@ static int stream_prepare(Job *job)
     unfiltered_base = bdrv_skip_filters(base);
     bdrv_graph_rdunlock_main_loop();
 
-    if (bdrv_cow_child(unfiltered_bs)) {
+    if (unfiltered_bs_cow) {
         const char *base_id = NULL, *base_fmt = NULL;
         if (unfiltered_base) {
             base_id = s->backing_file_str ?: unfiltered_base->filename;
             if (unfiltered_base->drv) {
-                base_fmt = unfiltered_base->drv->format_name;
+                if (s->backing_mask_protocol &&
+                    unfiltered_base->drv->protocol_name) {
+                    base_fmt = "raw";
+                } else {
+                    base_fmt = unfiltered_base->drv->format_name;
+                }
             }
         }
 
+        bdrv_graph_wrlock();
         bdrv_set_backing_hd_drained(unfiltered_bs, base, &local_err);
+        bdrv_graph_wrunlock();
 
         /*
          * This call will do I/O, so the graph can change again from here on.
@@ -245,6 +253,7 @@ static const BlockJobDriver stream_job_driver = {
 
 void stream_start(const char *job_id, BlockDriverState *bs,
                   BlockDriverState *base, const char *backing_file_str,
+                  bool backing_mask_protocol,
                   BlockDriverState *bottom,
                   int creation_flags, int64_t speed,
                   BlockdevOnError on_error,
@@ -266,6 +275,8 @@ void stream_start(const char *job_id, BlockDriverState *bs,
     assert(!(base && bottom));
     assert(!(backing_file_str && bottom));
 
+    bdrv_graph_rdlock_main_loop();
+
     if (bottom) {
         /*
          * New simple interface. The code is written in terms of old interface
@@ -278,13 +289,11 @@ void stream_start(const char *job_id, BlockDriverState *bs,
         assert(!bottom->drv->is_filter);
         base_overlay = above_base = bottom;
     } else {
-        GRAPH_RDLOCK_GUARD_MAINLOOP();
-
         base_overlay = bdrv_find_overlay(bs, base);
         if (!base_overlay) {
             error_setg(errp, "'%s' is not in the backing chain of '%s'",
                        base->node_name, bs->node_name);
-            return;
+            goto out_rdlock;
         }
 
         /*
@@ -306,7 +315,7 @@ void stream_start(const char *job_id, BlockDriverState *bs,
     if (bs_read_only) {
         /* Hold the chain during reopen */
         if (bdrv_freeze_backing_chain(bs, above_base, errp) < 0) {
-            return;
+            goto out_rdlock;
         }
 
         ret = bdrv_reopen_set_read_only(bs, false, errp);
@@ -315,10 +324,12 @@ void stream_start(const char *job_id, BlockDriverState *bs,
         bdrv_unfreeze_backing_chain(bs, above_base);
 
         if (ret < 0) {
-            return;
+            goto out_rdlock;
         }
     }
 
+    bdrv_graph_rdunlock_main_loop();
+
     opts = qdict_new();
 
     qdict_put_str(opts, "driver", "copy-on-read");
@@ -362,7 +373,7 @@ void stream_start(const char *job_id, BlockDriverState *bs,
      * already have our own plans. Also don't allow resize as the image size is
      * queried only at the job start and then cached.
      */
-    bdrv_graph_wrlock(bs);
+    bdrv_graph_wrlock();
     if (block_job_add_bdrv(&s->common, "active node", bs, 0,
                            basic_flags | BLK_PERM_WRITE, errp)) {
         bdrv_graph_wrunlock();
@@ -394,6 +405,7 @@ void stream_start(const char *job_id, BlockDriverState *bs,
     s->base_overlay = base_overlay;
     s->above_base = above_base;
     s->backing_file_str = g_strdup(backing_file_str);
+    s->backing_mask_protocol = backing_mask_protocol;
     s->cor_filter_bs = cor_filter_bs;
     s->target_bs = bs;
     s->bs_read_only = bs_read_only;
@@ -413,4 +425,8 @@ fail:
     if (bs_read_only) {
         bdrv_reopen_set_read_only(bs, true, NULL);
     }
+    return;
+
+out_rdlock:
+    bdrv_graph_rdunlock_main_loop();
 }