[PATCH v7 26/47] block: Improve get_allocated_file_size's default

[Max Reitz]

There are two practical problems with bdrv_get_allocated_file_size()'s
default right now:
(1) For drivers with children, we should generally sum all their sizes
    instead of just passing the request through to bs->file.  The latter
    is good for filters, but not so much for format drivers.

(2) Filters need not have bs->file, so we should actually go to the
    filtered child instead of hard-coding bs->file.

And we can make the whole default implementation more idiomatic by using
the three generic functions added by the previous patch.

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/block.c b/block.c
index fc01ce90b3..a19f243997 100644
--- a/block.c
+++ b/block.c
@@ -4997,10 +4997,21 @@ int64_t bdrv_get_allocated_file_size(BlockDriverState 
*bs)
     if (drv->bdrv_get_allocated_file_size) {
         return drv->bdrv_get_allocated_file_size(bs);
     }
-    if (bs->file) {
-        return bdrv_get_allocated_file_size(bs->file->bs);
+
+    if (drv->bdrv_file_open) {
+        /*
+         * Protocol drivers default to -ENOTSUP (most of their data is
+         * not stored in any of their children (if they even have any),
+         * so there is no generic way to figure it out).
+         */
+        return bdrv_notsup_allocated_file_size(bs);
+    } else if (drv->is_filter) {
+        /* Filter drivers default to the size of their primary child */
+        return bdrv_primary_allocated_file_size(bs);
+    } else {
+        /* Other drivers default to summing their children's sizes */
+        return bdrv_sum_allocated_file_size(bs);
     }
-    return -ENOTSUP;
 }
 
 /**
-- 
2.26.2