[10/29] qcow2-bitmap: add IN_USE flag

Commit Message

Vladimir Sementsov-Ogievskiy Aug. 8, 2016, 3:05 p.m. UTC

This flag means that the bitmap is now in use by the software or was not
successfully saved. In any way, with this flag set the bitmap data must
be considered inconsistent and should not be loaded.
With current implementation this flag is never set, as we just remove
bitmaps from the image after loading. But it defined in qcow2 spec and
must be handled. Also, it can be used in future, if async schemes of
bitmap loading/saving are implemented.

Signed-off-by: Vladimir Sementsov-Ogievskiy <[e-mail]>
---
 block/qcow2-bitmap.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

Patch

diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c
index 43a9bb9..19f8203 100644
--- a/block/qcow2-bitmap.c
+++ b/block/qcow2-bitmap.c
@@ -44,7 +44,8 @@ 
 #define BME_MAX_NAME_SIZE 1023
 
 /* Bitmap directory entry flags */
-#define BME_RESERVED_FLAGS 0xffffffff
+#define BME_RESERVED_FLAGS 0xfffffffe
+#define BME_FLAG_IN_USE 1
 
 /* bits [1, 8] U [56, 63] are reserved */
 #define BME_TABLE_ENTRY_RESERVED_MASK 0xff000000000001fe
@@ -487,6 +488,11 @@  static BdrvDirtyBitmap *load_bitmap(BlockDriverState *bs,
     BdrvDirtyBitmap *bitmap = NULL;
     char *name = g_strndup((char *)(bmh + 1), bmh->name_size);
 
+    if (bmh->flags & BME_FLAG_IN_USE) {
+        error_setg(errp, "Bitmap '%s' is in use", name);
+        goto fail;
+    }
+
     ret = bitmap_table_load(bs, bmh, &bitmap_table);
     if (ret < 0) {
         error_setg_errno(errp, -ret,
@@ -795,7 +801,8 @@  void qcow2_bitmap_store(BlockDriverState *bs,
             return;
         }
 
-        if (bmh->bitmap_table_offset) {
+        if ((bmh->bitmap_table_offset != 0) ||
+                !(bmh->flags & BME_FLAG_IN_USE)) {
             error_setg(errp,
                        "The bitmap with same name already exists, but was"
                        "not loaded.");
@@ -820,7 +827,7 @@  void qcow2_bitmap_store(BlockDriverState *bs,
         }
     } else {
         ret = directory_set(bs, bmh, granularity, table_offset, table_size,
-                            bmh->flags);
+                            bmh->flags & ~BME_FLAG_IN_USE);
         if (ret < 0) {
             error_setg_errno(errp, ret, "Can't update dirty bitmap in qcow2.");
             goto fail;