[Qemu-devel] [PATCH 10/17] block: store persistent dirty bitmaps

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

Persistent dirty bitmaps are the bitmaps, for which the new field
BdrvDirtyBitmap.file is not NULL. We save all persistent dirty bitmaps
owned by BlockDriverState in corresponding bdrv_close().
BdrvDirtyBitmap.file is a BlockDriverState, where we want to save the
bitmap. It may be set in bdrv_dirty_bitmap_set_file() only once.
bdrv_ref/bdrv_unref are used for BdrvDirtyBitmap.file to be sure that
files will be closed and resources will be freed.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 block.c               | 33 +++++++++++++++++++++++++++++++++
 include/block/block.h |  3 +++
 2 files changed, 36 insertions(+)

diff --git a/block.c b/block.c
index 69d7c30..492abb4 100644
--- a/block.c
+++ b/block.c
@@ -73,6 +73,8 @@ struct BdrvDirtyBitmap {
     BdrvDirtyBitmap *successor; /* Anonymous child; implies frozen status */
     char *name;                 /* Optional non-empty unique ID */
     int64_t size;               /* Size of the bitmap (Number of sectors) */
+    BlockDriverState *file;     /* File where bitmap is loaded from (and should
+                                   be saved to) */
     bool disabled;              /* Bitmap is read-only */
     QLIST_ENTRY(BdrvDirtyBitmap) list;
 };
@@ -1897,6 +1899,7 @@ void bdrv_reopen_abort(BDRVReopenState *reopen_state)
 void bdrv_close(BlockDriverState *bs)
 {
     BdrvAioNotifier *ban, *ban_next;
+    BdrvDirtyBitmap *bm, *bm_next;
 
     if (bs->job) {
         block_job_cancel_sync(bs->job);
@@ -1906,6 +1909,15 @@ void bdrv_close(BlockDriverState *bs)
     bdrv_drain(bs); /* in case flush left pending I/O */
     notifier_list_notify(&bs->close_notifiers, bs);
 
+    /* save and release persistent dirty bitmaps */
+    QLIST_FOREACH_SAFE(bm, &bs->dirty_bitmaps, list, bm_next) {
+        if (bm->file) {
+            bdrv_store_dirty_bitmap(bm);
+            bdrv_unref(bm->file);
+            bdrv_release_dirty_bitmap(bs, bm);
+        }
+    }
+
     if (bs->drv) {
         BdrvChild *child, *next;
 
@@ -3362,6 +3374,18 @@ bool bdrv_load_check_dirty_bitmap(BlockDriverState *file, const char *name)
     return false;
 }
 
+int bdrv_store_dirty_bitmap(BdrvDirtyBitmap *bitmap)
+{
+    BlockDriverState *bs = bitmap->file;
+
+    if (bs == NULL || bs->drv == NULL ||
+            bs->drv->bdrv_dirty_bitmap_store == NULL) {
+        return -EINVAL;
+    }
+
+    return bs->drv->bdrv_dirty_bitmap_store(bs, bitmap);
+}
+
 BdrvDirtyBitmap *bdrv_create_dirty_bitmap(BlockDriverState *bs,
                                           uint32_t granularity,
                                           const char *name,
@@ -3532,6 +3556,15 @@ void bdrv_release_dirty_bitmap(BlockDriverState *bs, BdrvDirtyBitmap *bitmap)
     }
 }
 
+void bdrv_dirty_bitmap_set_file(BdrvDirtyBitmap *bitmap, BlockDriverState *file)
+{
+    assert(bitmap->file == NULL);
+    bitmap->file = file;
+    if (file != NULL) {
+        bdrv_ref(file);
+    }
+}
+
 void bdrv_disable_dirty_bitmap(BdrvDirtyBitmap *bitmap)
 {
     assert(!bdrv_dirty_bitmap_frozen(bitmap));
diff --git a/include/block/block.h b/include/block/block.h
index 5e95e51..4b9b898 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -491,6 +491,8 @@ BdrvDirtyBitmap *bdrv_find_dirty_bitmap(BlockDriverState *bs,
                                         const char *name);
 void bdrv_dirty_bitmap_make_anon(BdrvDirtyBitmap *bitmap);
 void bdrv_release_dirty_bitmap(BlockDriverState *bs, BdrvDirtyBitmap *bitmap);
+void bdrv_dirty_bitmap_set_file(BdrvDirtyBitmap *bitmap,
+                                BlockDriverState *file);
 void bdrv_disable_dirty_bitmap(BdrvDirtyBitmap *bitmap);
 void bdrv_enable_dirty_bitmap(BdrvDirtyBitmap *bitmap);
 BlockDirtyInfoList *bdrv_query_dirty_bitmaps(BlockDriverState *bs);
@@ -532,6 +534,7 @@ HBitmap *bdrv_create_meta_bitmap(BdrvDirtyBitmap *bitmap,
 void bdrv_release_meta_bitmap(BdrvDirtyBitmap *bitmap);
 
 bool bdrv_load_check_dirty_bitmap(BlockDriverState *file, const char *name);
+int bdrv_store_dirty_bitmap(BdrvDirtyBitmap *bitmap);
 
 void bdrv_enable_copy_on_read(BlockDriverState *bs);
 void bdrv_disable_copy_on_read(BlockDriverState *bs);
-- 
2.1.4