[Qemu-devel] [PATCH v8 06/10] qmp: Add block-dirty-bitmap-enable and block-dirty-bitmap-disable

[John Snow <jsnow@redhat.com>]

From: Fam Zheng <famz@redhat.com>

This allows to put the dirty bitmap into a disabled state where no more
writes will be tracked.

It will be used before backup or writing to persistent file.

Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>
---
 block.c               | 15 +++++++++++++
 blockdev.c            | 61 +++++++++++++++++++++++++++++++++++++++++++++++++++
 include/block/block.h |  2 ++
 qapi/block-core.json  | 28 +++++++++++++++++++++++
 qmp-commands.hx       | 10 +++++++++
 5 files changed, 116 insertions(+)

diff --git a/block.c b/block.c
index 40cb9cf..1aa723b 100644
--- a/block.c
+++ b/block.c
@@ -56,6 +56,7 @@ struct BdrvDirtyBitmap {
     int64_t size;
     int64_t granularity;
     char *name;
+    bool enabled;
     QLIST_ENTRY(BdrvDirtyBitmap) list;
 };
 
@@ -5361,6 +5362,7 @@ BdrvDirtyBitmap *bdrv_create_dirty_bitmap(BlockDriverState *bs,
     bitmap->granularity = granularity;
     bitmap->bitmap = hbitmap_alloc(bitmap->size, ffs(sector_granularity) - 1);
     bitmap->name = g_strdup(name);
+    bitmap->enabled = true;
     QLIST_INSERT_HEAD(&bs->dirty_bitmaps, bitmap, list);
     return bitmap;
 }
@@ -5379,6 +5381,16 @@ void bdrv_release_dirty_bitmap(BlockDriverState *bs, BdrvDirtyBitmap *bitmap)
     }
 }
 
+void bdrv_disable_dirty_bitmap(BdrvDirtyBitmap *bitmap)
+{
+    bitmap->enabled = false;
+}
+
+void bdrv_enable_dirty_bitmap(BdrvDirtyBitmap *bitmap)
+{
+    bitmap->enabled = true;
+}
+
 BlockDirtyInfoList *bdrv_query_dirty_bitmaps(BlockDriverState *bs)
 {
     BdrvDirtyBitmap *bm;
@@ -5447,6 +5459,9 @@ void bdrv_set_dirty(BlockDriverState *bs, int64_t cur_sector,
 {
     BdrvDirtyBitmap *bitmap;
     QLIST_FOREACH(bitmap, &bs->dirty_bitmaps, list) {
+        if (!bitmap->enabled) {
+            continue;
+        }
         hbitmap_set(bitmap->bitmap, cur_sector, nr_sectors);
     }
 }
diff --git a/blockdev.c b/blockdev.c
index af1152f..276a31b 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1159,6 +1159,41 @@ SnapshotInfo *qmp_blockdev_snapshot_delete_internal_sync(const char *device,
     return info;
 }
 
+/**
+ * Return a dirty bitmap (if present), after validating
+ * the device and bitmap names. Returns NULL on error,
+ * including when the device and/or bitmap is not found.
+ */
+static BdrvDirtyBitmap *block_dirty_bitmap_lookup(const char *device,
+                                                  const char *name,
+                                                  Error **errp)
+{
+    BlockDriverState *bs;
+    BdrvDirtyBitmap *bitmap;
+
+    if (!device) {
+        error_setg(errp, "Device cannot be NULL");
+        return NULL;
+    }
+    if (!name) {
+        error_setg(errp, "Bitmap name cannot be NULL");
+        return NULL;
+    }
+
+    bs = bdrv_lookup_bs(device, NULL, errp);
+    if (!bs) {
+        return NULL;
+    }
+
+    bitmap = bdrv_find_dirty_bitmap(bs, name);
+    if (!bitmap) {
+        error_setg(errp, "Dirty bitmap not found: %s", name);
+        return NULL;
+    }
+
+    return bitmap;
+}
+
 /* New and old BlockDriverState structs for group snapshots */
 
 typedef struct BlkTransactionState BlkTransactionState;
@@ -1864,6 +1899,32 @@ void qmp_block_dirty_bitmap_remove(const char *device, const char *name,
     bdrv_release_dirty_bitmap(bs, bitmap);
 }
 
+void qmp_block_dirty_bitmap_enable(const char *device, const char *name,
+                                   Error **errp)
+{
+    BdrvDirtyBitmap *bitmap;
+
+    bitmap = block_dirty_bitmap_lookup(device, name, errp);
+    if (!bitmap) {
+        return;
+    }
+
+    bdrv_enable_dirty_bitmap(bitmap);
+}
+
+void qmp_block_dirty_bitmap_disable(const char *device, const char *name,
+                                    Error **errp)
+{
+    BdrvDirtyBitmap *bitmap;
+
+    bitmap = block_dirty_bitmap_lookup(device, name, errp);
+    if (!bitmap) {
+        return;
+    }
+
+    bdrv_disable_dirty_bitmap(bitmap);
+}
+
 int do_drive_del(Monitor *mon, const QDict *qdict, QObject **ret_data)
 {
     const char *id = qdict_get_str(qdict, "id");
diff --git a/include/block/block.h b/include/block/block.h
index 9326705..14a0632 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -440,6 +440,8 @@ BdrvDirtyBitmap *bdrv_copy_dirty_bitmap(BlockDriverState *bs,
                                         const BdrvDirtyBitmap *bitmap,
                                         const char *name);
 void bdrv_release_dirty_bitmap(BlockDriverState *bs, BdrvDirtyBitmap *bitmap);
+void bdrv_disable_dirty_bitmap(BdrvDirtyBitmap *bitmap);
+void bdrv_enable_dirty_bitmap(BdrvDirtyBitmap *bitmap);
 BlockDirtyInfoList *bdrv_query_dirty_bitmaps(BlockDriverState *bs);
 uint64_t bdrv_dbm_calc_def_granularity(BlockDriverState *bs);
 int64_t bdrv_dirty_bitmap_granularity(BlockDriverState *bs,
diff --git a/qapi/block-core.json b/qapi/block-core.json
index 51638b3..d77f19d 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -919,6 +919,34 @@
   'data': 'BlockDirtyBitmap' }
 
 ##
+# @block-dirty-bitmap-enable
+#
+# Enable a dirty bitmap on the device
+#
+# Returns: nothing on success
+#          If @device is not a valid block device, DeviceNotFound
+#          If @name is not found, GenericError with an explaining message
+#
+# Since 2.3
+##
+{'command': 'block-dirty-bitmap-enable',
+  'data': 'BlockDirtyBitmap' }
+
+##
+# @block-dirty-bitmap-disable
+#
+# Disable a dirty bitmap on the device
+#
+# Returns: nothing on success
+#          If @device is not a valid block device, DeviceNotFound
+#          If @name is not found, GenericError with an explaining message
+#
+# Since 2.3
+##
+{'command': 'block-dirty-bitmap-disable',
+  'data': 'BlockDirtyBitmap' }
+
+##
 # @block_set_io_throttle:
 #
 # Change I/O throttle limits for a block drive.
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 94d3293..cc31e22 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -1211,6 +1211,16 @@ EQMP
         .args_type  = "device:B,name:s",
         .mhandler.cmd_new = qmp_marshal_input_block_dirty_bitmap_remove,
     },
+    {
+        .name       = "block-dirty-bitmap-enable",
+        .args_type  = "device:B,name:s",
+        .mhandler.cmd_new = qmp_marshal_input_block_dirty_bitmap_enable,
+    },
+    {
+        .name       = "block-dirty-bitmap-disable",
+        .args_type  = "device:B,name:s",
+        .mhandler.cmd_new = qmp_marshal_input_block_dirty_bitmap_disable,
+    },
 
 SQMP
 
-- 
1.9.3