block/dirty-bitmaps: add block_dirty_bitmap_check function

Instead of checking against busy, inconsistent, or read only directly,
use a check function with permissions bits that let us streamline the
checks without reproducing them in many places.

Included in this patch are permissions changes that simply add the
inconsistent check to existing permissions call spots, without
addressing existing bugs.

In general, this means that busy+readonly checks become BDRV_BITMAP_DEFAULT,
which checks against all three conditions. busy-only checks become
BDRV_BITMAP_ALLOW_RO.

Notably, remove allows inconsistent bitmaps, so it doesn't follow the pattern.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190301191545.8728-4-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

1 files changed, 30 insertions, 12 deletions

diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
index 4a2349d9dd..6170f3a454 100644
--- a/block/dirty-bitmap.c
+++ b/block/dirty-bitmap.c
@@ -174,7 +174,7 @@ bool bdrv_dirty_bitmap_has_successor(BdrvDirtyBitmap *bitmap)
     return bitmap->successor;
 }
 
-bool bdrv_dirty_bitmap_busy(BdrvDirtyBitmap *bitmap)
+static bool bdrv_dirty_bitmap_busy(const BdrvDirtyBitmap *bitmap)
 {
     return bitmap->busy;
 }
@@ -236,6 +236,33 @@ static bool bdrv_dirty_bitmap_recording(BdrvDirtyBitmap *bitmap)
                                  !bitmap->successor->disabled);
 }
 
+int bdrv_dirty_bitmap_check(const BdrvDirtyBitmap *bitmap, uint32_t flags,
+                            Error **errp)
+{
+    if ((flags & BDRV_BITMAP_BUSY) && bdrv_dirty_bitmap_busy(bitmap)) {
+        error_setg(errp, "Bitmap '%s' is currently in use by another"
+                   " operation and cannot be used", bitmap->name);
+        return -1;
+    }
+
+    if ((flags & BDRV_BITMAP_RO) && bdrv_dirty_bitmap_readonly(bitmap)) {
+        error_setg(errp, "Bitmap '%s' is readonly and cannot be modified",
+                   bitmap->name);
+        return -1;
+    }
+
+    if ((flags & BDRV_BITMAP_INCONSISTENT) &&
+        bdrv_dirty_bitmap_inconsistent(bitmap)) {
+        error_setg(errp, "Bitmap '%s' is inconsistent and cannot be used",
+                   bitmap->name);
+        error_append_hint(errp, "Try block-dirty-bitmap-remove to delete"
+                          " this bitmap from disk");
+        return -1;
+    }
+
+    return 0;
+}
+
 /**
  * Create a successor bitmap destined to replace this bitmap after an operation.
  * Requires that the bitmap is not marked busy and has no successor.
@@ -248,9 +275,7 @@ int bdrv_dirty_bitmap_create_successor(BlockDriverState *bs,
     uint64_t granularity;
     BdrvDirtyBitmap *child;
 
-    if (bdrv_dirty_bitmap_busy(bitmap)) {
-        error_setg(errp, "Cannot create a successor for a bitmap that is "
-                   "in-use by an operation");
+    if (bdrv_dirty_bitmap_check(bitmap, BDRV_BITMAP_BUSY, errp)) {
         return -1;
     }
     if (bdrv_dirty_bitmap_has_successor(bitmap)) {
@@ -796,17 +821,10 @@ void bdrv_merge_dirty_bitmap(BdrvDirtyBitmap *dest, const BdrvDirtyBitmap *src,
 
     qemu_mutex_lock(dest->mutex);
 
-    if (bdrv_dirty_bitmap_busy(dest)) {
-        error_setg(errp, "Bitmap '%s' is currently in use by another"
-        " operation and cannot be modified", dest->name);
+    if (bdrv_dirty_bitmap_check(dest, BDRV_BITMAP_DEFAULT, errp)) {
         goto out;
     }
 
-    if (bdrv_dirty_bitmap_readonly(dest)) {
-        error_setg(errp, "Bitmap '%s' is readonly and cannot be modified",
-                   dest->name);
-        goto out;
-    }
 
     if (!hbitmap_can_merge(dest->bitmap, src->bitmap)) {
         error_setg(errp, "Bitmaps are incompatible and can't be merged");