Re: [Qemu-block] [PATCH v3 1/5] block/dirty-bitmaps: add user_modifiable status checker

[Vladimir Sementsov-Ogievskiy]

26.09.2018 14:53, Vladimir Sementsov-Ogievskiy wrote:

26.09.2018 02:49, 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 <js...@redhat.com>
---
  block/dirty-bitmap.c         |  6 ++++++
  blockdev.c                   | 29 ++++++++---------------------
  include/block/dirty-bitmap.h |  1 +
  3 files changed, 15 insertions(+), 21 deletions(-)

diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
index 8ac933cf1c..fc10543ab0 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_modifiable(BdrvDirtyBitmap *bitmap) {
+    return !(bdrv_dirty_bitmap_frozen(bitmap) ||
+             bdrv_dirty_bitmap_qmp_locked(bitmap));
+}

to reduce number of '!', we may use opposite check, for ex "bdrv_dirty_bitmap_user_locked".

bad reason to rewrite the whole series, so, ignore this comment)

anyway,
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>

+

  void bdrv_dirty_bitmap_set_qmp_locked(BdrvDirtyBitmap *bitmap, bool qmp_locked)

  {
      qemu_mutex_lock(bitmap->mutex);
diff --git a/blockdev.c b/blockdev.c
index 670ae5bbde..dedcebb0fa 100644
--- a/blockdev.c
+++ b/blockdev.c

@@ -2009,11 +2009,8 @@ static void block_dirty_bitmap_clear_prepare(BlkActionState *common,

          return;
      }
  -    if (bdrv_dirty_bitmap_frozen(state->bitmap)) {
-        error_setg(errp, "Cannot modify a frozen bitmap");
-        return;
-    } else if (bdrv_dirty_bitmap_qmp_locked(state->bitmap)) {
-        error_setg(errp, "Cannot modify a locked bitmap");
+    if (!bdrv_dirty_bitmap_user_modifiable(state->bitmap)) {

+        error_setg(errp, "Cannot modify a bitmap in-use by another operation");

          return;
      } else if (!bdrv_dirty_bitmap_enabled(state->bitmap)) {
          error_setg(errp, "Cannot clear a disabled bitmap");

@@ -2882,15 +2879,10 @@ void qmp_block_dirty_bitmap_remove(const char *node, const char *name,

          return;
      }
  -    if (bdrv_dirty_bitmap_frozen(bitmap)) {
+    if (!bdrv_dirty_bitmap_user_modifiable(bitmap)) {
          error_setg(errp,

-                   "Bitmap '%s' is currently frozen and cannot be removed",

-                   name);
-        return;
-    } else if (bdrv_dirty_bitmap_qmp_locked(bitmap)) {
-        error_setg(errp,

-                   "Bitmap '%s' is currently locked and cannot be removed",

-                   name);

+                   "Bitmap '%s' is currently in-use by another operation and"

+                   " cannot be removed", name);
          return;
      }

  @@ -2920,15 +2912,10 @@ void qmp_block_dirty_bitmap_clear(const char *node, const char *name,

          return;
      }
  -    if (bdrv_dirty_bitmap_frozen(bitmap)) {
+    if (!bdrv_dirty_bitmap_user_modifiable(bitmap)) {
          error_setg(errp,

-                   "Bitmap '%s' is currently frozen and cannot be modified",

-                   name);
-        return;
-    } else if (bdrv_dirty_bitmap_qmp_locked(bitmap)) {
-        error_setg(errp,

-                   "Bitmap '%s' is currently locked and cannot be modified",

-                   name);

+                   "Bitmap '%s' is currently in-use by another operation"

+                   " and cannot be cleared", name);
          return;
      } else if (!bdrv_dirty_bitmap_enabled(bitmap)) {
          error_setg(errp,
diff --git a/include/block/dirty-bitmap.h b/include/block/dirty-bitmap.h
index 201ff7f20b..92cf7e39d2 100644
--- a/include/block/dirty-bitmap.h
+++ b/include/block/dirty-bitmap.h
@@ -94,6 +94,7 @@ bool bdrv_has_readonly_bitmaps(BlockDriverState *bs);
  bool bdrv_dirty_bitmap_get_autoload(const BdrvDirtyBitmap *bitmap);
  bool bdrv_dirty_bitmap_get_persistance(BdrvDirtyBitmap *bitmap);
  bool bdrv_dirty_bitmap_qmp_locked(BdrvDirtyBitmap *bitmap);
+bool bdrv_dirty_bitmap_user_modifiable(BdrvDirtyBitmap *bitmap);
  bool bdrv_has_changed_persistent_bitmaps(BlockDriverState *bs);
  BdrvDirtyBitmap *bdrv_dirty_bitmap_next(BlockDriverState *bs,
                                          BdrvDirtyBitmap *bitmap);

--
Best regards,
Vladimir