[Qemu-devel] [PATCH 06/17] qcow2-dirty-bitmap: add qcow2_dirty_bitmap_load()

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

This function loads block dirty bitmap from qcow2.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 block/qcow2-dirty-bitmap.c | 155 +++++++++++++++++++++++++++++++++++++++++++++
 block/qcow2.c              |   2 +
 block/qcow2.h              |   5 ++
 include/block/block_int.h  |   5 ++
 4 files changed, 167 insertions(+)

diff --git a/block/qcow2-dirty-bitmap.c b/block/qcow2-dirty-bitmap.c
index 1260d1d..ea50137 100644
--- a/block/qcow2-dirty-bitmap.c
+++ b/block/qcow2-dirty-bitmap.c
@@ -99,6 +99,13 @@ static int check_constraints(int cluster_size,
     return fail ? -EINVAL : 0;
 }
 
+static QCowDirtyBitmapHeader *bitmap_header(BDRVQcowState *s,
+                                            QCowDirtyBitmap *bitmap)
+{
+    return (QCowDirtyBitmapHeader *)
+           (s->dirty_bitmap_directory + bitmap->offset);
+}
+
 static int directory_read(BlockDriverState *bs)
 {
     int ret;
@@ -195,3 +202,151 @@ out:
     }
     return ret;
 }
+
+static QCowDirtyBitmap *find_dirty_bitmap_by_name(BlockDriverState *bs,
+                                                  const char *name)
+{
+    BDRVQcowState *s = bs->opaque;
+    QCowDirtyBitmap *bm, *end = s->dirty_bitmaps + s->nb_dirty_bitmaps;
+
+    for (bm = s->dirty_bitmaps; bm < end; ++bm) {
+        if (strcmp(bm->name, name) == 0) {
+            return bm;
+        }
+    }
+
+    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 BDRVQcowState *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);
+}
+
+/* load_bitmap()
+ * load dirty bitmap from Dirty Bitmap Table
+ * Dirty Bitmap Table entries are assumed to be in big endian format */
+static int load_bitmap(BlockDriverState *bs,
+                       const uint64_t *dirty_bitmap_table,
+                       uint32_t dirty_bitmap_table_size,
+                       BdrvDirtyBitmap *bitmap)
+{
+    int ret = 0;
+    BDRVQcowState *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_data_size(bitmap, bm_size));
+
+    if (tab_size > dirty_bitmap_table_size) {
+        return -EINVAL;
+    }
+
+    bdrv_clear_dirty_bitmap(bitmap);
+
+    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 = be64_to_cpu(dirty_bitmap_table[i]);
+
+        if (offset & DBM_TABLE_ENTRY_RESERVED_MASK) {
+            ret = -EINVAL;
+            goto finish;
+        }
+
+        /* zero offset means cluster unallocated */
+        if (offset) {
+            ret = bdrv_pread(bs->file, offset, buf, cl_size);
+            if (ret < 0) {
+                goto finish;
+            }
+            bdrv_dirty_bitmap_deserialize_part(bitmap, buf, sector, end);
+        }
+    }
+    ret = 0;
+
+    bdrv_dirty_bitmap_deserialize_finish(bitmap);
+
+finish:
+    g_free(buf);
+
+    return ret;
+}
+
+BdrvDirtyBitmap * qcow2_dirty_bitmap_load(BlockDriverState *bs_for,
+                                          BlockDriverState *bs_file,
+                                          const char *name,
+                                          Error **errp)
+{
+    BDRVQcowState *s = bs_file->opaque;
+    int ret;
+    QCowDirtyBitmap *bm;
+    QCowDirtyBitmapHeader *bmh;
+    uint64_t *dirty_bitmap_table = NULL;
+    uint32_t granularity;
+    uint64_t size = bdrv_nb_sectors(bs_for);
+    BdrvDirtyBitmap *bitmap = NULL;
+
+    bm = find_dirty_bitmap_by_name(bs_file, name);
+    if (bm == NULL) {
+        error_setg(errp, "Could not find bitmap '%s' in the node '%s'", name,
+                   bdrv_get_device_or_node_name(bs_file));
+        return NULL;
+    }
+    bmh = bitmap_header(s, bm);
+
+    if (size != bmh->nb_virtual_bits) {
+        error_setg(errp,
+                   "Bitmap '%s' in the node '%s' has size = %" PRIu64
+                   "when requested size (for node %s) = %" PRIu64,
+                   name, bdrv_get_device_or_node_name(bs_file),
+                   bmh->nb_virtual_bits,
+                   bdrv_get_device_or_node_name(bs_for), size);
+        return NULL;
+    }
+
+
+    dirty_bitmap_table = g_try_malloc(bmh->dirty_bitmap_table_size * sizeof(uint64_t));
+    if (dirty_bitmap_table == NULL) {
+        error_setg_errno(errp, -ENOMEM, "Could not allocate Dirty Bitmap Table");
+        return NULL;
+    }
+
+    ret = bdrv_pread(bs_file->file, bmh->dirty_bitmap_table_offset, dirty_bitmap_table,
+                     bmh->dirty_bitmap_table_size * sizeof(uint64_t));
+    if (ret < 0) {
+        error_setg_errno(errp, -ret, "Could not read dirty_bitmap_table table from image");
+        goto finish;
+    }
+
+    granularity = BDRV_SECTOR_SIZE << bmh->granularity_bits;
+    bitmap = bdrv_create_dirty_bitmap(bs_for, granularity, name, errp);
+    if (bitmap == NULL) {
+        error_setg_errno(errp, -ENOMEM, "Could not create dirty bitmap");
+        goto finish;
+    }
+
+    ret = load_bitmap(bs_file, dirty_bitmap_table, bmh->dirty_bitmap_table_size, bitmap);
+    if (ret < 0) {
+        error_setg_errno(errp, -ret, "Could not read bitmap from image");
+        goto finish;
+    }
+
+finish:
+    if (*errp != NULL) {
+        bdrv_release_dirty_bitmap(bs_for, bitmap);
+        bitmap = NULL;
+    }
+    g_free(dirty_bitmap_table);
+
+    return bitmap;
+}
diff --git a/block/qcow2.c b/block/qcow2.c
index 76c331b..58ebdd3 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -2965,6 +2965,8 @@ BlockDriver bdrv_qcow2 = {
     .bdrv_get_info          = qcow2_get_info,
     .bdrv_get_specific_info = qcow2_get_specific_info,
 
+    .bdrv_dirty_bitmap_load = qcow2_dirty_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 5016fa1..51d1907 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -608,6 +608,11 @@ int qcow2_read_snapshots(BlockDriverState *bs);
 void qcow2_free_dirty_bitmaps(BlockDriverState *bs);
 int qcow2_read_dirty_bitmaps(BlockDriverState *bs);
 
+BdrvDirtyBitmap *qcow2_dirty_bitmap_load(BlockDriverState *bs_for,
+                                         BlockDriverState *bs_file,
+                                         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 14ad4c3..f982adc 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -204,6 +204,11 @@ struct BlockDriver {
     int (*bdrv_get_info)(BlockDriverState *bs, BlockDriverInfo *bdi);
     ImageInfoSpecific *(*bdrv_get_specific_info)(BlockDriverState *bs);
 
+    BdrvDirtyBitmap *(*bdrv_dirty_bitmap_load)(BlockDriverState *bs_for,
+                                               BlockDriverState *bs_file,
+                                               const char *name,
+                                               Error **errp);
+
     int (*bdrv_save_vmstate)(BlockDriverState *bs, QEMUIOVector *qiov,
                              int64_t pos);
     int (*bdrv_load_vmstate)(BlockDriverState *bs, uint8_t *buf,
-- 
2.1.4