[Qemu-devel] [PATCH 05/30] block: update in-memory backing file and format

[Kevin Wolf <kwolf@redhat.com>]

From: Paolo Bonzini <pbonzini@redhat.com>

These are needed to print "info block" output correctly.  QCOW2 does this
because it needs it to write the header, but QED does not, and common code
is the right place to do it.

Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c        |   11 +++++++++--
 block/stream.c |   11 -----------
 2 files changed, 9 insertions(+), 13 deletions(-)

diff --git a/block.c b/block.c
index 068e41d..dbd60e3 100644
--- a/block.c
+++ b/block.c
@@ -1459,6 +1459,7 @@ int bdrv_change_backing_file(BlockDriverState *bs,
     const char *backing_file, const char *backing_fmt)
 {
     BlockDriver *drv = bs->drv;
+    int ret;
 
     /* Backing file format doesn't make sense without a backing file */
     if (backing_fmt && !backing_file) {
@@ -1466,10 +1467,16 @@ int bdrv_change_backing_file(BlockDriverState *bs,
     }
 
     if (drv->bdrv_change_backing_file != NULL) {
-        return drv->bdrv_change_backing_file(bs, backing_file, backing_fmt);
+        ret = drv->bdrv_change_backing_file(bs, backing_file, backing_fmt);
     } else {
-        return -ENOTSUP;
+        ret = -ENOTSUP;
+    }
+
+    if (ret == 0) {
+        pstrcpy(bs->backing_file, sizeof(bs->backing_file), backing_file ?: "");
+        pstrcpy(bs->backing_format, sizeof(bs->backing_format), backing_fmt ?: "");
     }
+    return ret;
 }
 
 static int bdrv_check_byte_request(BlockDriverState *bs, int64_t offset,
diff --git a/block/stream.c b/block/stream.c
index 6724af2..b7e1ad4 100644
--- a/block/stream.c
+++ b/block/stream.c
@@ -96,17 +96,6 @@ static void close_unused_images(BlockDriverState *top, BlockDriverState *base,
         bdrv_delete(unused);
     }
     top->backing_hd = base;
-
-    pstrcpy(top->backing_file, sizeof(top->backing_file), "");
-    pstrcpy(top->backing_format, sizeof(top->backing_format), "");
-    if (base_id) {
-        pstrcpy(top->backing_file, sizeof(top->backing_file), base_id);
-        if (base->drv) {
-            pstrcpy(top->backing_format, sizeof(top->backing_format),
-                    base->drv->format_name);
-        }
-    }
-
 }
 
 /*
-- 
1.7.6.5