[Qemu-devel] [PATCH v2 3/4] block/dirty-bitmaps: add block_dirty_bitmap_check function

[John Snow <jsnow@redhat.com>]

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.

As a side effect, this adds consistency checks to all the QMP
interfaces for bitmap manipulation.

Signed-off-by: John Snow <jsnow@redhat.com>
---
 block/dirty-bitmap.c           | 39 ++++++++++++++++++++-------
 blockdev.c                     | 49 +++++++---------------------------
 include/block/dirty-bitmap.h   | 13 ++++++++-
 migration/block-dirty-bitmap.c | 12 +++------
 nbd/server.c                   |  3 +--
 5 files changed, 54 insertions(+), 62 deletions(-)

diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
index 4e8f931659..2e7fd81866 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(BdrvDirtyBitmap *bitmap) {
     return bitmap->busy;
 }
 
@@ -235,6 +235,33 @@ static bool bdrv_dirty_bitmap_recording(BdrvDirtyBitmap *bitmap)
                                  !bitmap->successor->disabled);
 }
 
+int bdrv_dirty_bitmap_check(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 user_locked and has no successor.
@@ -792,15 +819,7 @@ 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);
-        goto out;
-    }
-
-    if (bdrv_dirty_bitmap_readonly(dest)) {
-        error_setg(errp, "Bitmap '%s' is readonly and cannot be modified",
-                   dest->name);
+    if (bdrv_dirty_bitmap_check(dest, BDRV_BITMAP_DEFAULT, errp)) {
         goto out;
     }
 
diff --git a/blockdev.c b/blockdev.c
index cbce44877d..5d74479ba7 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -2007,11 +2007,7 @@ static void block_dirty_bitmap_clear_prepare(BlkActionState *common,
         return;
     }
 
-    if (bdrv_dirty_bitmap_busy(state->bitmap)) {
-        error_setg(errp, "Cannot modify a bitmap in use by another operation");
-        return;
-    } else if (bdrv_dirty_bitmap_readonly(state->bitmap)) {
-        error_setg(errp, "Cannot clear a readonly bitmap");
+    if (bdrv_dirty_bitmap_check(state->bitmap, BDRV_BITMAP_DEFAULT, errp)) {
         return;
     }
 
@@ -2056,10 +2052,7 @@ static void block_dirty_bitmap_enable_prepare(BlkActionState *common,
         return;
     }
 
-    if (bdrv_dirty_bitmap_busy(state->bitmap)) {
-        error_setg(errp,
-                   "Bitmap '%s' is currently in use by another operation"
-                   " and cannot be enabled", action->name);
+    if (bdrv_dirty_bitmap_check(state->bitmap, BDRV_BITMAP_ALLOW_RO, errp)) {
         return;
     }
 
@@ -2097,10 +2090,7 @@ static void block_dirty_bitmap_disable_prepare(BlkActionState *common,
         return;
     }
 
-    if (bdrv_dirty_bitmap_busy(state->bitmap)) {
-        error_setg(errp,
-                   "Bitmap '%s' is currently in use by another operation"
-                   " and cannot be disabled", action->name);
+    if (bdrv_dirty_bitmap_check(state->bitmap, BDRV_BITMAP_ALLOW_RO, errp)) {
         return;
     }
 
@@ -2891,10 +2881,7 @@ void qmp_block_dirty_bitmap_remove(const char *node, const char *name,
         return;
     }
 
-    if (bdrv_dirty_bitmap_busy(bitmap)) {
-        error_setg(errp,
-                   "Bitmap '%s' is currently in use by another operation and"
-                   " cannot be removed", name);
+    if (bdrv_dirty_bitmap_check(bitmap, BDRV_BITMAP_BUSY, errp)) {
         return;
     }
 
@@ -2930,13 +2917,7 @@ void qmp_block_dirty_bitmap_clear(const char *node, const char *name,
         return;
     }
 
-    if (bdrv_dirty_bitmap_busy(bitmap)) {
-        error_setg(errp,
-                   "Bitmap '%s' is currently in use by another operation"
-                   " and cannot be cleared", name);
-        return;
-    } else if (bdrv_dirty_bitmap_readonly(bitmap)) {
-        error_setg(errp, "Bitmap '%s' is readonly and cannot be cleared", name);
+    if (bdrv_dirty_bitmap_check(bitmap, BDRV_BITMAP_DEFAULT, errp)) {
         return;
     }
 
@@ -2954,10 +2935,7 @@ void qmp_block_dirty_bitmap_enable(const char *node, const char *name,
         return;
     }
 
-    if (bdrv_dirty_bitmap_busy(bitmap)) {
-        error_setg(errp,
-                   "Bitmap '%s' is currently in use by another operation"
-                   " and cannot be enabled", name);
+    if (bdrv_dirty_bitmap_check(bitmap, BDRV_BITMAP_ALLOW_RO, errp)) {
         return;
     }
 
@@ -2975,10 +2953,7 @@ void qmp_block_dirty_bitmap_disable(const char *node, const char *name,
         return;
     }
 
-    if (bdrv_dirty_bitmap_busy(bitmap)) {
-        error_setg(errp,
-                   "Bitmap '%s' is currently in use by another operation"
-                   " and cannot be disabled", name);
+    if (bdrv_dirty_bitmap_check(bitmap, BDRV_BITMAP_ALLOW_RO, errp)) {
         return;
     }
 
@@ -3551,10 +3526,7 @@ static BlockJob *do_drive_backup(DriveBackup *backup, JobTxn *txn,
             bdrv_unref(target_bs);
             goto out;
         }
-        if (bdrv_dirty_bitmap_busy(bmap)) {
-            error_setg(errp,
-                       "Bitmap '%s' is currently in use by another operation"
-                       " and cannot be used for backup", backup->bitmap);
+        if (bdrv_dirty_bitmap_check(bmap, BDRV_BITMAP_ALLOW_RO, errp)) {
             goto out;
         }
     }
@@ -3664,10 +3636,7 @@ BlockJob *do_blockdev_backup(BlockdevBackup *backup, JobTxn *txn,
             error_setg(errp, "Bitmap '%s' could not be found", backup->bitmap);
             goto out;
         }
-        if (bdrv_dirty_bitmap_busy(bmap)) {
-            error_setg(errp,
-                       "Bitmap '%s' is currently in use by another operation"
-                       " and cannot be used for backup", backup->bitmap);
+        if (bdrv_dirty_bitmap_check(bmap, BDRV_BITMAP_ALLOW_RO, errp)) {
             goto out;
         }
     }
diff --git a/include/block/dirty-bitmap.h b/include/block/dirty-bitmap.h
index b270773f7e..ee98b5014b 100644
--- a/include/block/dirty-bitmap.h
+++ b/include/block/dirty-bitmap.h
@@ -5,6 +5,16 @@
 #include "qapi/qapi-types-block-core.h"
 #include "qemu/hbitmap.h"
 
+typedef enum BitmapCheckFlags {
+    BDRV_BITMAP_BUSY = 1,
+    BDRV_BITMAP_RO = 2,
+    BDRV_BITMAP_INCONSISTENT = 4,
+} BitmapCheckFlags;
+
+#define BDRV_BITMAP_DEFAULT (BDRV_BITMAP_BUSY | BDRV_BITMAP_RO |        \
+                             BDRV_BITMAP_INCONSISTENT)
+#define BDRV_BITMAP_ALLOW_RO (BDRV_BITMAP_BUSY | BDRV_BITMAP_INCONSISTENT)
+
 BdrvDirtyBitmap *bdrv_create_dirty_bitmap(BlockDriverState *bs,
                                           uint32_t granularity,
                                           const char *name,
@@ -24,6 +34,8 @@ BdrvDirtyBitmap *bdrv_reclaim_dirty_bitmap(BlockDriverState *bs,
 void bdrv_dirty_bitmap_enable_successor(BdrvDirtyBitmap *bitmap);
 BdrvDirtyBitmap *bdrv_find_dirty_bitmap(BlockDriverState *bs,
                                         const char *name);
+int bdrv_dirty_bitmap_check(BdrvDirtyBitmap *bitmap, uint32_t flags,
+                            Error **errp);
 void bdrv_release_dirty_bitmap(BlockDriverState *bs, BdrvDirtyBitmap *bitmap);
 void bdrv_release_named_dirty_bitmaps(BlockDriverState *bs);
 void bdrv_remove_persistent_dirty_bitmap(BlockDriverState *bs,
@@ -93,7 +105,6 @@ 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_inconsistent(BdrvDirtyBitmap *bitmap);
-bool bdrv_dirty_bitmap_busy(BdrvDirtyBitmap *bitmap);
 bool bdrv_has_changed_persistent_bitmaps(BlockDriverState *bs);
 BdrvDirtyBitmap *bdrv_dirty_bitmap_next(BlockDriverState *bs,
                                         BdrvDirtyBitmap *bitmap);
diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
index 7057fff242..0fcf897f32 100644
--- a/migration/block-dirty-bitmap.c
+++ b/migration/block-dirty-bitmap.c
@@ -274,6 +274,7 @@ static int init_dirty_bitmap_migration(void)
     BdrvDirtyBitmap *bitmap;
     DirtyBitmapMigBitmapState *dbms;
     BdrvNextIterator it;
+    Error *local_err = NULL;
 
     dirty_bitmap_mig_state.bulk_completed = false;
     dirty_bitmap_mig_state.prev_bs = NULL;
@@ -301,15 +302,8 @@ static int init_dirty_bitmap_migration(void)
                 goto fail;
             }
 
-            if (bdrv_dirty_bitmap_busy(bitmap)) {
-                error_report("Can't migrate a bitmap that is in use by another operation: '%s'",
-                             bdrv_dirty_bitmap_name(bitmap));
-                goto fail;
-            }
-
-            if (bdrv_dirty_bitmap_readonly(bitmap)) {
-                error_report("Can't migrate read-only dirty bitmap: '%s",
-                             bdrv_dirty_bitmap_name(bitmap));
+            if (bdrv_dirty_bitmap_check(bitmap, BDRV_BITMAP_DEFAULT, &local_err)) {
+                error_report_err(local_err);
                 goto fail;
             }
 
diff --git a/nbd/server.c b/nbd/server.c
index 02773e2836..9b87c7f243 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -1510,8 +1510,7 @@ NBDExport *nbd_export_new(BlockDriverState *bs, uint64_t dev_offset,
             goto fail;
         }
 
-        if (bdrv_dirty_bitmap_busy(bm)) {
-            error_setg(errp, "Bitmap '%s' is in use", bitmap);
+        if (bdrv_dirty_bitmap_check(bm, BDRV_BITMAP_ALLOW_RO, errp)) {
             goto fail;
         }
 
-- 
2.17.2