block: per caller dirty bitmap

Previously a BlockDriverState has only one dirty bitmap, so only one
caller (e.g. a block job) can keep track of writing. This changes the
dirty bitmap to a list and creates a BdrvDirtyBitmap for each caller, the
lifecycle is managed with these new functions:

    bdrv_create_dirty_bitmap
    bdrv_release_dirty_bitmap

Where BdrvDirtyBitmap is a linked list wrapper structure of HBitmap.

In place of bdrv_set_dirty_tracking, a BdrvDirtyBitmap pointer argument
is added to these functions, since each caller has its own dirty bitmap:

    bdrv_get_dirty
    bdrv_dirty_iter_init
    bdrv_get_dirty_count

bdrv_set_dirty and bdrv_reset_dirty prototypes are unchanged but will
internally walk the list of all dirty bitmaps and set them one by one.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

2 files changed, 8 insertions, 5 deletions

diff --git a/include/block/block.h b/include/block/block.h
index 4d9e67c7eb..33ae9a9b5a 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -419,12 +419,15 @@ void *qemu_blockalign(BlockDriverState *bs, size_t size);
 bool bdrv_qiov_is_aligned(BlockDriverState *bs, QEMUIOVector *qiov);
 
 struct HBitmapIter;
-void bdrv_set_dirty_tracking(BlockDriverState *bs, int granularity);
-int bdrv_get_dirty(BlockDriverState *bs, int64_t sector);
+typedef struct BdrvDirtyBitmap BdrvDirtyBitmap;
+BdrvDirtyBitmap *bdrv_create_dirty_bitmap(BlockDriverState *bs, int granularity);
+void bdrv_release_dirty_bitmap(BlockDriverState *bs, BdrvDirtyBitmap *bitmap);
+int bdrv_get_dirty(BlockDriverState *bs, BdrvDirtyBitmap *bitmap, int64_t sector);
 void bdrv_set_dirty(BlockDriverState *bs, int64_t cur_sector, int nr_sectors);
 void bdrv_reset_dirty(BlockDriverState *bs, int64_t cur_sector, int nr_sectors);
-void bdrv_dirty_iter_init(BlockDriverState *bs, struct HBitmapIter *hbi);
-int64_t bdrv_get_dirty_count(BlockDriverState *bs);
+void bdrv_dirty_iter_init(BlockDriverState *bs,
+                          BdrvDirtyBitmap *bitmap, struct HBitmapIter *hbi);
+int64_t bdrv_get_dirty_count(BlockDriverState *bs, BdrvDirtyBitmap *bitmap);
 
 void bdrv_enable_copy_on_read(BlockDriverState *bs);
 void bdrv_disable_copy_on_read(BlockDriverState *bs);
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 95140b6ccf..3c5e9cbfc0 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -318,7 +318,7 @@ struct BlockDriverState {
     bool iostatus_enabled;
     BlockDeviceIoStatus iostatus;
     char device_name[32];
-    HBitmap *dirty_bitmap;
+    QLIST_HEAD(, BdrvDirtyBitmap) dirty_bitmaps;
     int refcnt;
     int in_use; /* users other than guest access, eg. block migration */
     QTAILQ_ENTRY(BlockDriverState) list;