[Qemu-block] [PATCH 07/29] qcow2-bitmap: add qcow2_bitmap_load()

[Vladimir Sementsov-Ogievskiy]

This function loads block dirty bitmap from qcow2.

Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
---
 block/qcow2-bitmap.c      | 165 ++++++++++++++++++++++++++++++++++++++++++++++
 block/qcow2.c             |   2 +
 block/qcow2.h             |   3 +
 include/block/block_int.h |   4 ++
 4 files changed, 174 insertions(+)

diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c
index 91ddd5f..280b7bf 100644
--- a/block/qcow2-bitmap.c
+++ b/block/qcow2-bitmap.c
@@ -53,6 +53,10 @@
          h < (QCow2BitmapHeader *)((uint8_t *)(dir) + size); \
          h = next_dir_entry(h))
 
+#define for_each_bitmap_header(h, s) \
+    for_each_bitmap_header_in_dir(h, s->bitmap_directory, \
+                                  s->bitmap_directory_size)
+
 typedef enum BitmapType {
     BT_DIRTY_TRACKING_BITMAP = 1
 } BitmapType;
@@ -66,6 +70,15 @@ static inline void bitmap_header_to_cpu(QCow2BitmapHeader *h)
     be32_to_cpus(&h->extra_data_size);
 }
 
+static inline void bitmap_table_to_cpu(uint64_t *bitmap_table, size_t size)
+{
+    size_t i;
+
+    for (i = 0; i < size; ++i) {
+        be64_to_cpus(&bitmap_table[i]);
+    }
+}
+
 static inline int calc_dir_entry_size(size_t name_size)
 {
     return align_offset(sizeof(QCow2BitmapHeader) + name_size, 8);
@@ -145,3 +158,155 @@ int qcow2_read_bitmaps(BlockDriverState *bs, Error **errp)
 
     return 0;
 }
+
+static QCow2BitmapHeader *find_bitmap_by_name(BlockDriverState *bs,
+                                              const char *name)
+{
+    BDRVQcow2State *s = bs->opaque;
+    QCow2BitmapHeader *h;
+
+    for_each_bitmap_header(h, s) {
+        if (strncmp((char *)(h + 1), name, h->name_size) == 0) {
+            return h;
+        }
+    }
+
+    return NULL;
+}
+
+/* dirty sectors in cluster is a number of sectors in the image, corresponding
+ * to one cluster of bitmap data */
+static uint64_t dirty_sectors_in_cluster(const BDRVQcow2State *s,
+                                         const BdrvDirtyBitmap *bitmap)
+{
+    uint32_t sector_granularity =
+            bdrv_dirty_bitmap_granularity(bitmap) >> BDRV_SECTOR_BITS;
+
+    return (uint64_t)sector_granularity * (s->cluster_size << 3);
+}
+
+static int load_bitmap_data(BlockDriverState *bs,
+                            const uint64_t *dirty_bitmap_table,
+                            uint32_t dirty_bitmap_table_size,
+                            BdrvDirtyBitmap *bitmap)
+{
+    int ret = 0;
+    BDRVQcow2State *s = bs->opaque;
+    uint64_t sector, dsc;
+    uint64_t bm_size = bdrv_dirty_bitmap_size(bitmap);
+    int cl_size = s->cluster_size;
+    uint8_t *buf = NULL;
+    uint32_t i, tab_size =
+            size_to_clusters(s,
+                bdrv_dirty_bitmap_serialization_size(bitmap, 0, bm_size));
+
+    if (tab_size != dirty_bitmap_table_size) {
+        return -EINVAL;
+    }
+
+    bdrv_clear_dirty_bitmap(bitmap, NULL);
+
+    buf = g_malloc0(cl_size);
+    dsc = dirty_sectors_in_cluster(s, bitmap);
+    for (i = 0, sector = 0; i < tab_size; ++i, sector += dsc) {
+        uint64_t end = MIN(bm_size, sector + dsc);
+        uint64_t offset = dirty_bitmap_table[i];
+
+        if (offset == 1) {
+            bdrv_dirty_bitmap_deserialize_ones(bitmap, sector, end, false);
+        } else if (offset > 1) {
+            ret = bdrv_pread(bs->file, offset, buf, cl_size);
+            if (ret < 0) {
+                goto finish;
+            }
+            bdrv_dirty_bitmap_deserialize_part(bitmap, buf, sector, end, 
false);
+        }
+    }
+    ret = 0;
+
+    bdrv_dirty_bitmap_deserialize_finish(bitmap);
+
+finish:
+    g_free(buf);
+
+    return ret;
+}
+
+static int bitmap_table_load(BlockDriverState *bs, QCow2BitmapHeader *bmh,
+                             uint64_t **table)
+{
+    int ret;
+
+    *table = g_try_new(uint64_t, bmh->bitmap_table_size);
+    if (*table == NULL) {
+        return -ENOMEM;
+    }
+
+    ret = bdrv_pread(bs->file, bmh->bitmap_table_offset,
+                     *table, bmh->bitmap_table_size * sizeof(uint64_t));
+    if (ret < 0) {
+        g_free(*table);
+        *table = NULL;
+        return ret;
+    }
+
+    bitmap_table_to_cpu(*table, bmh->bitmap_table_size);
+
+    return 0;
+}
+
+static BdrvDirtyBitmap *load_bitmap(BlockDriverState *bs,
+                                    QCow2BitmapHeader *bmh, Error **errp)
+{
+    int ret;
+    uint64_t *bitmap_table = NULL;
+    uint32_t granularity;
+    BdrvDirtyBitmap *bitmap = NULL;
+    char *name = g_strndup((char *)(bmh + 1), bmh->name_size);
+
+    ret = bitmap_table_load(bs, bmh, &bitmap_table);
+    if (ret < 0) {
+        error_setg_errno(errp, -ret,
+                         "Could not read bitmap_table table from image");
+        goto fail;
+    }
+
+    granularity = 1U << bmh->granularity_bits;
+    bitmap = bdrv_create_dirty_bitmap(bs, granularity, name, errp);
+    if (bitmap == NULL) {
+        goto fail;
+    }
+
+    ret = load_bitmap_data(bs, bitmap_table, bmh->bitmap_table_size,
+                           bitmap);
+    if (ret < 0) {
+        error_setg_errno(errp, -ret, "Could not read bitmap from image");
+        goto fail;
+    }
+
+    g_free(name);
+    g_free(bitmap_table);
+    return bitmap;
+
+fail:
+    g_free(name);
+    g_free(bitmap_table);
+    if (bitmap != NULL) {
+        bdrv_release_dirty_bitmap(bs, bitmap);
+    }
+
+    return NULL;
+}
+
+BdrvDirtyBitmap *qcow2_bitmap_load(BlockDriverState *bs, const char *name,
+                                   Error **errp)
+{
+    QCow2BitmapHeader *h = find_bitmap_by_name(bs, name);
+    if (h == NULL) {
+        error_setg(errp, "Could not find bitmap '%s' in the node '%s'", name,
+                   bdrv_get_device_or_node_name(bs));
+        return NULL;
+    }
+
+    return load_bitmap(bs, h, errp);
+}
diff --git a/block/qcow2.c b/block/qcow2.c
index 91ef4df..74dab08 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -3423,6 +3423,8 @@ BlockDriver bdrv_qcow2 = {
     .bdrv_get_info          = qcow2_get_info,
     .bdrv_get_specific_info = qcow2_get_specific_info,
 
+    .bdrv_dirty_bitmap_load = qcow2_bitmap_load,
+
     .bdrv_save_vmstate    = qcow2_save_vmstate,
     .bdrv_load_vmstate    = qcow2_load_vmstate,
 
diff --git a/block/qcow2.h b/block/qcow2.h
index 7f6e023..573fc36 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -608,6 +608,9 @@ int qcow2_read_snapshots(BlockDriverState *bs);
 void qcow2_free_bitmaps(BlockDriverState *bs);
 int qcow2_read_bitmaps(BlockDriverState *bs, Error **errp);
 
+BdrvDirtyBitmap *qcow2_bitmap_load(BlockDriverState *bs, const char *name,
+                                   Error **errp);
+
 /* qcow2-cache.c functions */
 Qcow2Cache *qcow2_cache_create(BlockDriverState *bs, int num_tables);
 int qcow2_cache_destroy(BlockDriverState* bs, Qcow2Cache *c);
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 1fe0fd9..2c11ad7 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -224,6 +224,10 @@ struct BlockDriver {
     int (*bdrv_get_info)(BlockDriverState *bs, BlockDriverInfo *bdi);
     ImageInfoSpecific *(*bdrv_get_specific_info)(BlockDriverState *bs);
 
+    BdrvDirtyBitmap *(*bdrv_dirty_bitmap_load)(BlockDriverState *bs,
+                                               const char *name,
+                                               Error **errp);
+
     int coroutine_fn (*bdrv_save_vmstate)(BlockDriverState *bs,
                                           QEMUIOVector *qiov,
                                           int64_t pos);
-- 
1.8.3.1