[Qemu-devel] [PATCH 05/13] block: Hide HBitmap in block dirty bitmap interface

[Fam Zheng <famz@redhat.com>]

HBitmap is an implementation detail of block dirty bitmap that should be hidden
from users. Introduce a BdrvDirtyBitmapIter to encapsulate the underlying
HBitmapIter.

A small difference in the interface is, before, an HBitmapIter is initialized
in place, now the new BdrvDirtyBitmapIter must be dynamically allocated because
the structure definition is in block.c.

Two current users are converted too.

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 block/backup.c               | 14 ++++++++------
 block/dirty-bitmap.c         | 36 +++++++++++++++++++++++++++++++-----
 block/mirror.c               | 14 ++++++++------
 include/block/dirty-bitmap.h |  7 +++++--
 include/qemu/typedefs.h      |  1 +
 5 files changed, 53 insertions(+), 19 deletions(-)

diff --git a/block/backup.c b/block/backup.c
index 56ddec0..2388039 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -326,14 +326,14 @@ static int coroutine_fn backup_run_incremental(BackupBlockJob *job)
     int64_t end;
     int64_t last_cluster = -1;
     BlockDriverState *bs = job->common.bs;
-    HBitmapIter hbi;
+    BdrvDirtyBitmapIter *dbi;
 
     granularity = bdrv_dirty_bitmap_granularity(job->sync_bitmap);
     clusters_per_iter = MAX((granularity / BACKUP_CLUSTER_SIZE), 1);
-    bdrv_dirty_iter_init(job->sync_bitmap, &hbi);
+    dbi = bdrv_dirty_iter_new(job->sync_bitmap, 0);
 
     /* Find the next dirty sector(s) */
-    while ((sector = hbitmap_iter_next(&hbi)) != -1) {
+    while ((sector = bdrv_dirty_iter_next(dbi)) != -1) {
         cluster = sector / BACKUP_SECTORS_PER_CLUSTER;
 
         /* Fake progress updates for any clusters we skipped */
@@ -345,7 +345,7 @@ static int coroutine_fn backup_run_incremental(BackupBlockJob *job)
         for (end = cluster + clusters_per_iter; cluster < end; cluster++) {
             do {
                 if (yield_and_check(job)) {
-                    return ret;
+                    goto out;
                 }
                 ret = backup_do_cow(bs, cluster * BACKUP_SECTORS_PER_CLUSTER,
                                     BACKUP_SECTORS_PER_CLUSTER, &error_is_read,
@@ -353,7 +353,7 @@ static int coroutine_fn backup_run_incremental(BackupBlockJob *job)
                 if ((ret < 0) &&
                     backup_error_action(job, error_is_read, -ret) ==
                     BLOCK_ERROR_ACTION_REPORT) {
-                    return ret;
+                    goto out;
                 }
             } while (ret < 0);
         }
@@ -361,7 +361,7 @@ static int coroutine_fn backup_run_incremental(BackupBlockJob *job)
         /* If the bitmap granularity is smaller than the backup granularity,
          * we need to advance the iterator pointer to the next cluster. */
         if (granularity < BACKUP_CLUSTER_SIZE) {
-            bdrv_set_dirty_iter(&hbi, cluster * BACKUP_SECTORS_PER_CLUSTER);
+            bdrv_set_dirty_iter(dbi, cluster * BACKUP_SECTORS_PER_CLUSTER);
         }
 
         last_cluster = cluster - 1;
@@ -373,6 +373,8 @@ static int coroutine_fn backup_run_incremental(BackupBlockJob *job)
         job->common.offset += ((end - last_cluster - 1) * BACKUP_CLUSTER_SIZE);
     }
 
+out:
+    bdrv_dirty_iter_free(dbi);
     return ret;
 }
 
diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
index 7924c38..53cf88d 100644
--- a/block/dirty-bitmap.c
+++ b/block/dirty-bitmap.c
@@ -41,9 +41,15 @@ struct BdrvDirtyBitmap {
     char *name;                 /* Optional non-empty unique ID */
     int64_t size;               /* Size of the bitmap (Number of sectors) */
     bool disabled;              /* Bitmap is read-only */
+    int active_iterators;       /* How many iterators are active */
     QLIST_ENTRY(BdrvDirtyBitmap) list;
 };
 
+struct BdrvDirtyBitmapIter {
+    HBitmapIter hbi;
+    BdrvDirtyBitmap *bitmap;
+};
+
 BdrvDirtyBitmap *bdrv_find_dirty_bitmap(BlockDriverState *bs, const char *name)
 {
     BdrvDirtyBitmap *bm;
@@ -221,6 +227,7 @@ void bdrv_release_dirty_bitmap(BlockDriverState *bs, BdrvDirtyBitmap *bitmap)
     BdrvDirtyBitmap *bm, *next;
     QLIST_FOREACH_SAFE(bm, &bs->dirty_bitmaps, list, next) {
         if (bm == bitmap) {
+            assert(!bitmap->active_iterators);
             assert(!bdrv_dirty_bitmap_frozen(bm));
             QLIST_REMOVE(bitmap, list);
             hbitmap_free(bitmap->bitmap);
@@ -299,9 +306,29 @@ uint32_t bdrv_dirty_bitmap_granularity(BdrvDirtyBitmap *bitmap)
     return BDRV_SECTOR_SIZE << hbitmap_granularity(bitmap->bitmap);
 }
 
-void bdrv_dirty_iter_init(BdrvDirtyBitmap *bitmap, HBitmapIter *hbi)
+BdrvDirtyBitmapIter *bdrv_dirty_iter_new(BdrvDirtyBitmap *bitmap,
+                                         uint64_t first_sector)
 {
-    hbitmap_iter_init(hbi, bitmap->bitmap, 0);
+    BdrvDirtyBitmapIter *iter = g_new(BdrvDirtyBitmapIter, 1);
+    hbitmap_iter_init(&iter->hbi, bitmap->bitmap, first_sector);
+    iter->bitmap = bitmap;
+    bitmap->active_iterators++;
+    return iter;
+}
+
+void bdrv_dirty_iter_free(BdrvDirtyBitmapIter *iter)
+{
+    if (!iter) {
+        return;
+    }
+    assert(iter->bitmap->active_iterators > 0);
+    iter->bitmap->active_iterators--;
+    g_free(iter);
+}
+
+int64_t bdrv_dirty_iter_next(BdrvDirtyBitmapIter *iter)
+{
+    return hbitmap_iter_next(&iter->hbi);
 }
 
 void bdrv_set_dirty_bitmap(BdrvDirtyBitmap *bitmap,
@@ -354,10 +381,9 @@ void bdrv_set_dirty(BlockDriverState *bs, int64_t cur_sector,
 /**
  * Advance an HBitmapIter to an arbitrary offset.
  */
-void bdrv_set_dirty_iter(HBitmapIter *hbi, int64_t offset)
+void bdrv_set_dirty_iter(BdrvDirtyBitmapIter *iter, int64_t sector_num)
 {
-    assert(hbi->hb);
-    hbitmap_iter_init(hbi, hbi->hb, offset);
+    hbitmap_iter_init(&iter->hbi, iter->bitmap->bitmap, sector_num);
 }
 
 int64_t bdrv_get_dirty_count(BdrvDirtyBitmap *bitmap)
diff --git a/block/mirror.c b/block/mirror.c
index f201f2b..70ca844 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -52,7 +52,7 @@ typedef struct MirrorBlockJob {
     int64_t bdev_length;
     unsigned long *cow_bitmap;
     BdrvDirtyBitmap *dirty_bitmap;
-    HBitmapIter hbi;
+    BdrvDirtyBitmapIter *dbi;
     uint8_t *buf;
     QSIMPLEQ_HEAD(, MirrorBuffer) buf_free;
     int buf_free_count;
@@ -170,10 +170,11 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s)
 
     max_iov = MIN(source->bl.max_iov, s->target->bl.max_iov);
 
-    s->sector_num = hbitmap_iter_next(&s->hbi);
+    s->sector_num = bdrv_dirty_iter_next(s->dbi);
     if (s->sector_num < 0) {
-        bdrv_dirty_iter_init(s->dirty_bitmap, &s->hbi);
-        s->sector_num = hbitmap_iter_next(&s->hbi);
+        bdrv_dirty_iter_free(s->dbi);
+        s->dbi = bdrv_dirty_iter_new(s->dirty_bitmap, 0);
+        s->sector_num = bdrv_dirty_iter_next(s->dbi);
         trace_mirror_restart_iter(s, bdrv_get_dirty_count(s->dirty_bitmap));
         assert(s->sector_num >= 0);
     }
@@ -291,7 +292,7 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s)
          */
         if (next_sector > hbitmap_next_sector
             && bdrv_get_dirty(source, s->dirty_bitmap, next_sector)) {
-            hbitmap_next_sector = hbitmap_iter_next(&s->hbi);
+            hbitmap_next_sector = bdrv_dirty_iter_next(s->dbi);
         }
 
         next_sector += sectors_per_chunk;
@@ -502,7 +503,7 @@ static void coroutine_fn mirror_run(void *opaque)
         }
     }
 
-    bdrv_dirty_iter_init(s->dirty_bitmap, &s->hbi);
+    s->dbi = bdrv_dirty_iter_new(s->dirty_bitmap, 0);
     for (;;) {
         uint64_t delay_ns = 0;
         int64_t cnt;
@@ -615,6 +616,7 @@ immediate_exit:
     qemu_vfree(s->buf);
     g_free(s->cow_bitmap);
     g_free(s->in_flight_bitmap);
+    bdrv_dirty_iter_free(s->dbi);
     bdrv_release_dirty_bitmap(bs, s->dirty_bitmap);
     if (s->target->blk) {
         blk_iostatus_disable(s->target->blk);
diff --git a/include/block/dirty-bitmap.h b/include/block/dirty-bitmap.h
index 6175cf3..16bb15a 100644
--- a/include/block/dirty-bitmap.h
+++ b/include/block/dirty-bitmap.h
@@ -34,8 +34,11 @@ void bdrv_set_dirty_bitmap(BdrvDirtyBitmap *bitmap,
                            int64_t cur_sector, int nr_sectors);
 void bdrv_reset_dirty_bitmap(BdrvDirtyBitmap *bitmap,
                              int64_t cur_sector, int nr_sectors);
-void bdrv_dirty_iter_init(BdrvDirtyBitmap *bitmap, struct HBitmapIter *hbi);
-void bdrv_set_dirty_iter(struct HBitmapIter *hbi, int64_t offset);
+BdrvDirtyBitmapIter *bdrv_dirty_iter_new(BdrvDirtyBitmap *bitmap,
+                                         uint64_t first_sector);
+void bdrv_dirty_iter_free(BdrvDirtyBitmapIter *iter);
+int64_t bdrv_dirty_iter_next(BdrvDirtyBitmapIter *iter);
+void bdrv_set_dirty_iter(BdrvDirtyBitmapIter *hbi, int64_t sector_num);
 int64_t bdrv_get_dirty_count(BdrvDirtyBitmap *bitmap);
 void bdrv_dirty_bitmap_truncate(BlockDriverState *bs);
 
diff --git a/include/qemu/typedefs.h b/include/qemu/typedefs.h
index e83934e..0e9efcd 100644
--- a/include/qemu/typedefs.h
+++ b/include/qemu/typedefs.h
@@ -11,6 +11,7 @@ typedef struct AioContext AioContext;
 typedef struct AllwinnerAHCIState AllwinnerAHCIState;
 typedef struct AudioState AudioState;
 typedef struct BdrvDirtyBitmap BdrvDirtyBitmap;
+typedef struct BdrvDirtyBitmapIter BdrvDirtyBitmapIter;
 typedef struct BlockBackend BlockBackend;
 typedef struct BlockBackendRootState BlockBackendRootState;
 typedef struct BlockDriverState BlockDriverState;
-- 
2.4.3