qemu/qcow2-bitmaps-fix-qcow2_can_store_new_di.patch

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Date: Mon, 14 Oct 2019 14:51:25 +0300
Subject: qcow2-bitmaps: fix qcow2_can_store_new_dirty_bitmap

Git-commit: a1db8733d28d615bc0daeada6c406a6dd5c5d5ef

qcow2_can_store_new_dirty_bitmap works wrong, as it considers only
bitmaps already stored in the qcow2 image and ignores persistent
BdrvDirtyBitmap objects.

So, let's instead count persistent BdrvDirtyBitmaps. We load all qcow2
bitmaps on open, so there should not be any bitmap in the image for
which we don't have BdrvDirtyBitmaps version. If it is - it's a kind of
corruption, and no reason to check for corruptions here (open() and
close() are better places for it).

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20191014115126.15360-2-vsementsov@virtuozzo.com
Reviewed-by: Max Reitz <mreitz@redhat.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Bruce Rogers <brogers@suse.com>
---
 block/qcow2-bitmap.c | 41 ++++++++++++++++++-----------------------
 1 file changed, 18 insertions(+), 23 deletions(-)

diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c
index c6c8ebbe89d4252432bfb80e3426..d41f5d049b7d791ac30e1e36d3c5 100644
--- a/block/qcow2-bitmap.c
+++ b/block/qcow2-bitmap.c
@@ -1703,8 +1703,14 @@ bool coroutine_fn qcow2_co_can_store_new_dirty_bitmap(BlockDriverState *bs,
                                                       Error **errp)
 {
     BDRVQcow2State *s = bs->opaque;
-    bool found;
-    Qcow2BitmapList *bm_list;
+    BdrvDirtyBitmap *bitmap;
+    uint64_t bitmap_directory_size = 0;
+    uint32_t nb_bitmaps = 0;
+
+    if (bdrv_find_dirty_bitmap(bs, name)) {
+        error_setg(errp, "Bitmap already exists: %s", name);
+        return false;
+    }
 
     if (s->qcow_version < 3) {
         /* Without autoclear_features, we would always have to assume
@@ -1720,38 +1726,27 @@ bool coroutine_fn qcow2_co_can_store_new_dirty_bitmap(BlockDriverState *bs,
         goto fail;
     }
 
-    if (s->nb_bitmaps == 0) {
-        return true;
+    FOR_EACH_DIRTY_BITMAP(bs, bitmap) {
+        if (bdrv_dirty_bitmap_get_persistence(bitmap)) {
+            nb_bitmaps++;
+            bitmap_directory_size +=
+                calc_dir_entry_size(strlen(bdrv_dirty_bitmap_name(bitmap)), 0);
+        }
     }
+    nb_bitmaps++;
+    bitmap_directory_size += calc_dir_entry_size(strlen(name), 0);
 
-    if (s->nb_bitmaps >= QCOW2_MAX_BITMAPS) {
+    if (nb_bitmaps > QCOW2_MAX_BITMAPS) {
         error_setg(errp,
                    "Maximum number of persistent bitmaps is already reached");
         goto fail;
     }
 
-    if (s->bitmap_directory_size + calc_dir_entry_size(strlen(name), 0) >
-        QCOW2_MAX_BITMAP_DIRECTORY_SIZE)
-    {
+    if (bitmap_directory_size > QCOW2_MAX_BITMAP_DIRECTORY_SIZE) {
         error_setg(errp, "Not enough space in the bitmap directory");
         goto fail;
     }
 
-    qemu_co_mutex_lock(&s->lock);
-    bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
-                               s->bitmap_directory_size, errp);
-    qemu_co_mutex_unlock(&s->lock);
-    if (bm_list == NULL) {
-        goto fail;
-    }
-
-    found = find_bitmap_by_name(bm_list, name);
-    bitmap_list_free(bm_list);
-    if (found) {
-        error_setg(errp, "Bitmap with the same name is already stored");
-        goto fail;
-    }
-
     return true;
 
 fail: