qemu-img: Fail fast on convert --bitmaps with inconsistent bitmap

Waiting until the end of the convert operation (a potentially
time-consuming task) to finally detect that we can't copy a bitmap is
bad, comparing to failing fast up front.  Furthermore, this prevents
us from leaving a file behind with a bitmap that is not marked as
inconsistent even though it does not have sane contents.

This fixes the problems exposed in the previous patch to the iotest:
it adds a fast failure up front, and even if we don't fail early, it
ensures that any bitmap we add but do not properly populate is removed
again rather than left behind incomplete.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20210709153951.2801666-3-eblake@redhat.com>
[eblake: add a hint to the warning message, simplify name computation]
Reviewed-by: Nir Soffer <nsoffer@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

1 files changed, 26 insertions, 3 deletions

diff --git a/qemu-img.c b/qemu-img.c
index 797742a443..c5496e82e0 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -2101,6 +2101,29 @@ static int convert_do_copy(ImgConvertState *s)
     return s->ret;
 }
 
+/* Check that bitmaps can be copied, or output an error */
+static int convert_check_bitmaps(BlockDriverState *src)
+{
+    BdrvDirtyBitmap *bm;
+
+    if (!bdrv_supports_persistent_dirty_bitmap(src)) {
+        error_report("Source lacks bitmap support");
+        return -1;
+    }
+    FOR_EACH_DIRTY_BITMAP(src, bm) {
+        if (!bdrv_dirty_bitmap_get_persistence(bm)) {
+            continue;
+        }
+        if (bdrv_dirty_bitmap_inconsistent(bm)) {
+            error_report("Cannot copy inconsistent bitmap '%s'",
+                         bdrv_dirty_bitmap_name(bm));
+            error_printf("Try 'qemu-img bitmap --remove' to delete it\n");
+            return -1;
+        }
+    }
+    return 0;
+}
+
 static int convert_copy_bitmaps(BlockDriverState *src, BlockDriverState *dst)
 {
     BdrvDirtyBitmap *bm;
@@ -2127,6 +2150,7 @@ static int convert_copy_bitmaps(BlockDriverState *src, BlockDriverState *dst)
                               &err);
         if (err) {
             error_reportf_err(err, "Failed to populate bitmap %s: ", name);
+            qmp_block_dirty_bitmap_remove(dst->node_name, name, NULL);
             return -1;
         }
     }
@@ -2554,9 +2578,8 @@ static int img_convert(int argc, char **argv)
             ret = -1;
             goto out;
         }
-        if (!bdrv_supports_persistent_dirty_bitmap(blk_bs(s.src[0]))) {
-            error_report("Source lacks bitmap support");
-            ret = -1;
+        ret = convert_check_bitmaps(blk_bs(s.src[0]));
+        if (ret < 0) {
             goto out;
         }
     }