[Qemu-devel] [PATCH V7 06/14] block: add image info query function bdrv_query_image_info()

[Wenchao Xia]

  This patch add function bdrv_query_image_info(), which will return
image info in qmp object format. The implementation code are based
on the code moved from qemu-img.c, but use block layer function to get
snapshot info.
  A check with bdrv_can_read_snapshot(), was done before collecting
snapshot info.

Signed-off-by: Wenchao Xia <address@hidden>
---
 block.c               |   38 ++++++++++++++++++++++++++++++++------
 include/block/block.h |    5 +----
 qemu-img.c            |   13 +++++--------
 3 files changed, 38 insertions(+), 18 deletions(-)

diff --git a/block.c b/block.c
index 8d0145a..71fc9e7 100644
--- a/block.c
+++ b/block.c
@@ -2880,15 +2880,33 @@ SnapshotInfoList 
*bdrv_query_snapshot_infolist(BlockDriverState *bs,
     return head;
 }
 
-void collect_image_info(BlockDriverState *bs,
-                        ImageInfo *info,
-                        const char *filename)
+/* collect all internal snapshot info in a image for ImageInfo */
+static void collect_snapshots_info(BlockDriverState *bs,
+                                   ImageInfo *info,
+                                   Error **errp)
+{
+    SnapshotInfoList *info_list;
+
+    if (!bdrv_can_read_snapshot(bs)) {
+        return;
+    }
+    info_list = bdrv_query_snapshot_infolist(bs, NULL, NULL, errp);
+    if (info_list != NULL) {
+        info->has_snapshots = true;
+        info->snapshots = info_list;
+    }
+}
+
+static void collect_image_info(BlockDriverState *bs,
+                               ImageInfo *info)
 {
     uint64_t total_sectors;
-    char backing_filename[1024];
+    const char *backing_filename;
     char backing_filename2[1024];
     BlockDriverInfo bdi;
+    const char *filename;
 
+    filename = bs->filename;
     bdrv_get_geometry(bs, &total_sectors);
 
     info->filename        = g_strdup(filename);
@@ -2908,8 +2926,8 @@ void collect_image_info(BlockDriverState *bs,
         info->dirty_flag = bdi.is_dirty;
         info->has_dirty_flag = true;
     }
-    bdrv_get_backing_filename(bs, backing_filename, sizeof(backing_filename));
-    if (backing_filename[0] != '\0') {
+    backing_filename = bs->backing_file;
+    if (backing_filename && backing_filename[0] != '\0') {
         info->backing_filename = g_strdup(backing_filename);
         info->has_backing_filename = true;
         bdrv_get_full_backing_filename(bs, backing_filename2,
@@ -2928,6 +2946,14 @@ void collect_image_info(BlockDriverState *bs,
     }
 }
 
+ImageInfo *bdrv_query_image_info(BlockDriverState *bs, Error **errp)
+{
+    ImageInfo *info = g_new0(ImageInfo, 1);
+    collect_image_info(bs, info);
+    collect_snapshots_info(bs, info, errp);
+    return info;
+}
+
 BlockInfo *bdrv_query_info(BlockDriverState *bs)
 {
     BlockInfo *info = g_malloc0(sizeof(*info));
diff --git a/include/block/block.h b/include/block/block.h
index 51a14f2..f033807 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -326,6 +326,7 @@ SnapshotInfoList 
*bdrv_query_snapshot_infolist(BlockDriverState *bs,
                                                SnapshotFilterFunc filter,
                                                void *opaque,
                                                Error **errp);
+ImageInfo *bdrv_query_image_info(BlockDriverState *bs, Error **errp);
 BlockInfo *bdrv_query_info(BlockDriverState *s);
 BlockStats *bdrv_query_stats(const BlockDriverState *bs);
 bool bdrv_can_read_snapshot(BlockDriverState *bs);
@@ -456,8 +457,4 @@ int bdrv_debug_breakpoint(BlockDriverState *bs, const char 
*event,
                            const char *tag);
 int bdrv_debug_resume(BlockDriverState *bs, const char *tag);
 bool bdrv_debug_is_suspended(BlockDriverState *bs, const char *tag);
-
-void collect_image_info(BlockDriverState *bs,
-                        ImageInfo *info,
-                        const char *filename);
 #endif
diff --git a/qemu-img.c b/qemu-img.c
index 1034cc5..90f4bf4 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -1257,6 +1257,7 @@ static ImageInfoList *collect_image_info_list(const char 
*filename,
     ImageInfoList *head = NULL;
     ImageInfoList **last = &head;
     GHashTable *filenames;
+    Error *err = NULL;
 
     filenames = g_hash_table_new_full(g_str_hash, str_equal_func, NULL, NULL);
 
@@ -1278,14 +1279,10 @@ static ImageInfoList *collect_image_info_list(const 
char *filename,
             goto err;
         }
 
-        info = g_new0(ImageInfo, 1);
-        collect_image_info(bs, info, filename);
-        if (bdrv_can_read_snapshot(bs)) {
-            info->snapshots = bdrv_query_snapshot_infolist(bs, NULL,
-                                                           NULL, NULL);
-            if (info->snapshots) {
-                info->has_snapshots = true;
-            }
+        info = bdrv_query_image_info(bs, &err);
+        if (error_is_set(&err)) {
+            bdrv_delete(bs);
+            goto err;
         }
 
         elem = g_new0(ImageInfoList, 1);
-- 
1.7.1