Re: [Qemu-block] [PATCH v4 1/6] block/dirty-bitmaps: add user_locked status checker

[Vladimir Sementsov-Ogievskiy]

03.10.2018 02:02, John Snow wrote:

Instead of both frozen and qmp_locked checks, wrap it into one check.
frozen implies the bitmap is split in two (for backup), and shouldn't
be modified. qmp_locked implies it's being used by another operation,
like being exported over NBD. In both cases it means we shouldn't allow
the user to modify it in any meaningful way.

Replace any usages where we check both frozen and qmp_locked with the
new check.

Signed-off-by: John Snow <address@hidden>
---
 block/dirty-bitmap.c           |  6 ++++++
 blockdev.c                     | 29 ++++++++---------------------
 include/block/dirty-bitmap.h   |  1 +
 migration/block-dirty-bitmap.c | 10 ++--------
 4 files changed, 17 insertions(+), 29 deletions(-)

diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
index 8ac933cf1c..85bc668f6a 100644
--- a/block/dirty-bitmap.c
+++ b/block/dirty-bitmap.c
@@ -176,6 +176,12 @@ bool bdrv_dirty_bitmap_frozen(BdrvDirtyBitmap *bitmap)
     return bitmap->successor;
 }
 
+/* Both conditions disallow user-modification via QMP. */
+bool bdrv_dirty_bitmap_user_locked(BdrvDirtyBitmap *bitmap) {
+    return (bdrv_dirty_bitmap_frozen(bitmap) ||
+            bdrv_dirty_bitmap_qmp_locked(bitmap));

hmm, extra parentheses

+}
+
 void bdrv_dirty_bitmap_set_qmp_locked(BdrvDirtyBitmap *bitmap, bool qmp_locked)
 {
     qemu_mutex_lock(bitmap->mutex);

[...]

--- a/migration/block-dirty-bitmap.c
+++ b/migration/block-dirty-bitmap.c
@@ -301,14 +301,8 @@ static int init_dirty_bitmap_migration(void)
                 goto fail;
             }
 
-            if (bdrv_dirty_bitmap_frozen(bitmap)) {
-                error_report("Can't migrate frozen dirty bitmap: '%s",
-                             bdrv_dirty_bitmap_name(bitmap));
-                goto fail;
-            }
-
-            if (bdrv_dirty_bitmap_qmp_locked(bitmap)) {
-                error_report("Can't migrate locked dirty bitmap: '%s",
+            if (bdrv_dirty_bitmap_user_locked(bitmap)) {
+                error_report("Can't migrate a bitmap that is in use: '%s'",

"by another operation" like in other cases?

                              bdrv_dirty_bitmap_name(bitmap));
                 goto fail;
             }

anyway,
Reviewed-by: Vladimir Sementsov-Ogievskiy <address@hidden>

-- 
Best regards,
Vladimir