[Qemu-block] [PATCH 09/24] qcow2: add .bdrv_load_autoloading_dirty_bitmaps

[Vladimir Sementsov-Ogievskiy]

Auto loading bitmaps are bitmaps in Qcow2, with the AUTO flag set. They
are loaded when the image is opened and become BdrvDirtyBitmaps for the
corresponding drive.

Extra data in bitmaps is not supported for now.

Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
---
 block/Makefile.objs  |   2 +-
 block/qcow2-bitmap.c | 712 +++++++++++++++++++++++++++++++++++++++++++++++++++
 block/qcow2.c        |   2 +
 block/qcow2.h        |   3 +
 4 files changed, 718 insertions(+), 1 deletion(-)
 create mode 100644 block/qcow2-bitmap.c

diff --git a/block/Makefile.objs b/block/Makefile.objs
index 67a036a1df..b8b6cf38a0 100644
--- a/block/Makefile.objs
+++ b/block/Makefile.objs
@@ -1,5 +1,5 @@
 block-obj-y += raw_bsd.o qcow.o vdi.o vmdk.o cloop.o bochs.o vpc.o vvfat.o 
dmg.o
-block-obj-y += qcow2.o qcow2-refcount.o qcow2-cluster.o qcow2-snapshot.o 
qcow2-cache.o
+block-obj-y += qcow2.o qcow2-refcount.o qcow2-cluster.o qcow2-snapshot.o 
qcow2-cache.o qcow2-bitmap.o
 block-obj-y += qed.o qed-gencb.o qed-l2-cache.o qed-table.o qed-cluster.o
 block-obj-y += qed-check.o
 block-obj-y += vhdx.o vhdx-endian.o vhdx-log.o
diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c
new file mode 100644
index 0000000000..758622dcfc
--- /dev/null
+++ b/block/qcow2-bitmap.c
@@ -0,0 +1,712 @@
+/*
+ * Bitmaps for the QCOW version 2 format
+ *
+ * Copyright (c) 2014-2016 Vladimir Sementsov-Ogievskiy
+ *
+ * This file is derived from qcow2-snapshot.c, original copyright:
+ * Copyright (c) 2004-2006 Fabrice Bellard
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to 
deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "exec/log.h"
+
+#include "block/block_int.h"
+#include "block/qcow2.h"
+
+/* NOTICE: BME here means Bitmaps Extension and used as a namespace for
+ * _internal_ constants. Please do not use this _internal_ abbreviation for
+ * other needs and/or outside of this file. */
+
+/* Bitmap directory entry constraints */
+#define BME_MAX_TABLE_SIZE 0x8000000
+#define BME_MAX_PHYS_SIZE 0x20000000 /* restrict BdrvDirtyBitmap size in RAM */
+#define BME_MAX_GRANULARITY_BITS 31
+#define BME_MIN_GRANULARITY_BITS 9
+#define BME_MAX_NAME_SIZE 1023
+
+/* Bitmap directory entry flags */
+#define BME_RESERVED_FLAGS 0xfffffffcU
+#define BME_FLAG_IN_USE 1
+#define BME_FLAG_AUTO   (1U << 1)
+
+/* bits [1, 8] U [56, 63] are reserved */
+#define BME_TABLE_ENTRY_RESERVED_MASK 0xff000000000001feULL
+#define BME_TABLE_ENTRY_OFFSET_MASK 0x00fffffffffffe00ULL
+
+typedef struct QEMU_PACKED Qcow2BitmapDirEntry {
+    /* header is 8 byte aligned */
+    uint64_t bitmap_table_offset;
+
+    uint32_t bitmap_table_size;
+    uint32_t flags;
+
+    uint8_t type;
+    uint8_t granularity_bits;
+    uint16_t name_size;
+    uint32_t extra_data_size;
+    /* extra data follows  */
+    /* name follows  */
+} Qcow2BitmapDirEntry;
+
+typedef struct Qcow2Bitmap {
+    uint64_t table_offset;
+    uint32_t table_size;
+    uint32_t flags;
+    uint8_t granularity_bits;
+    char *name;
+
+    QSIMPLEQ_ENTRY(Qcow2Bitmap) entry;
+} Qcow2Bitmap;
+typedef QSIMPLEQ_HEAD(Qcow2BitmapList, Qcow2Bitmap) Qcow2BitmapList;
+
+typedef enum BitmapType {
+    BT_DIRTY_TRACKING_BITMAP = 1
+} BitmapType;
+
+static inline bool can_write(BlockDriverState *bs)
+{
+    return !bdrv_is_read_only(bs) && !(bdrv_get_flags(bs) & BDRV_O_INACTIVE);
+}
+
+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 int check_table_entry(uint64_t entry, int cluster_size)
+{
+    uint64_t offset;
+
+    if (cluster_size <= 0) {
+        return -EINVAL;
+    }
+
+    if (entry & BME_TABLE_ENTRY_RESERVED_MASK) {
+        return -EINVAL;
+    }
+
+    offset = entry & BME_TABLE_ENTRY_OFFSET_MASK;
+    if (offset != 0) {
+        /* if offset specified, bit 0 is reserved */
+        if (entry & 1) {
+            return -EINVAL;
+        }
+
+        if (offset % cluster_size != 0) {
+            return -EINVAL;
+        }
+    }
+
+    return 0;
+}
+
+static int bitmap_table_load(BlockDriverState *bs, Qcow2Bitmap *bm,
+                             uint64_t **bitmap_table)
+{
+    int ret;
+    BDRVQcow2State *s = bs->opaque;
+    uint32_t i;
+    uint64_t *table;
+
+    assert(bm->table_size != 0);
+    table = g_try_new(uint64_t, bm->table_size);
+    if (table == NULL) {
+        return -ENOMEM;
+    }
+
+    assert(bm->table_size <= BME_MAX_TABLE_SIZE);
+    ret = bdrv_pread(bs->file, bm->table_offset,
+                     table, bm->table_size * sizeof(uint64_t));
+    if (ret < 0) {
+        goto fail;
+    }
+
+    for (i = 0; i < bm->table_size; ++i) {
+        be64_to_cpus(&table[i]);
+        ret = check_table_entry(table[i], s->cluster_size);
+        if (ret < 0) {
+            goto fail;
+        }
+    }
+
+    *bitmap_table = table;
+    return 0;
+
+fail:
+    g_free(table);
+
+    return ret;
+}
+
+/* This function returns the number of disk sectors covered by a single cluster
+ * of bitmap data. */
+static uint64_t disk_sectors_in_bitmap_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);
+}
+
+/* bitmap table entries must satisfy specification constraints */
+static int load_bitmap_data(BlockDriverState *bs,
+                            const uint64_t *bitmap_table,
+                            uint32_t 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);
+    uint8_t *buf = NULL;
+    uint64_t i, tab_size =
+            size_to_clusters(s,
+                bdrv_dirty_bitmap_serialization_size(bitmap, 0, bm_size));
+
+    if (tab_size != bitmap_table_size || tab_size > BME_MAX_TABLE_SIZE) {
+        return -EINVAL;
+    }
+
+    bdrv_clear_dirty_bitmap(bitmap, NULL);
+
+    buf = g_malloc(s->cluster_size);
+    dsc = disk_sectors_in_bitmap_cluster(s, bitmap);
+    for (i = 0, sector = 0; i < tab_size; ++i, sector += dsc) {
+        uint64_t count = MIN(bm_size - sector, dsc);
+        uint64_t entry = bitmap_table[i];
+        uint64_t offset = entry & BME_TABLE_ENTRY_OFFSET_MASK;
+
+        assert(check_table_entry(entry, s->cluster_size) == 0);
+
+        if (offset == 0) {
+            if (entry & 1) {
+                bdrv_dirty_bitmap_deserialize_ones(bitmap, sector, count,
+                                                   false);
+            } else {
+                /* No need to deserialize zeros because the dirty bitmap is
+                 * already cleared */
+            }
+        } else {
+            ret = bdrv_pread(bs->file, offset, buf, s->cluster_size);
+            if (ret < 0) {
+                goto finish;
+            }
+            bdrv_dirty_bitmap_deserialize_part(bitmap, buf, sector, count,
+                                               false);
+        }
+    }
+    ret = 0;
+
+    bdrv_dirty_bitmap_deserialize_finish(bitmap);
+
+finish:
+    g_free(buf);
+
+    return ret;
+}
+
+static BdrvDirtyBitmap *load_bitmap(BlockDriverState *bs,
+                                    Qcow2Bitmap *bm, Error **errp)
+{
+    int ret;
+    uint64_t *bitmap_table = NULL;
+    uint32_t granularity;
+    BdrvDirtyBitmap *bitmap = NULL;
+
+    if (bm->flags & BME_FLAG_IN_USE) {
+        error_setg(errp, "Bitmap '%s' is in use", bm->name);
+        goto fail;
+    }
+
+    ret = bitmap_table_load(bs, bm, &bitmap_table);
+    if (ret < 0) {
+        error_setg_errno(errp, -ret,
+                         "Could not read bitmap_table table from image for "
+                         "bitmap '%s'", bm->name);
+        goto fail;
+    }
+
+    granularity = 1U << bm->granularity_bits;
+    bitmap = bdrv_create_dirty_bitmap(bs, granularity, bm->name, errp);
+    if (bitmap == NULL) {
+        goto fail;
+    }
+
+    ret = load_bitmap_data(bs, bitmap_table, bm->table_size,
+                           bitmap);
+    if (ret < 0) {
+        error_setg_errno(errp, -ret, "Could not read bitmap '%s' from image",
+                         bm->name);
+        goto fail;
+    }
+
+    g_free(bitmap_table);
+    return bitmap;
+
+fail:
+    g_free(bitmap_table);
+    if (bitmap != NULL) {
+        bdrv_release_dirty_bitmap(bs, bitmap);
+    }
+
+    return NULL;
+}
+
+/*
+ * Bitmap List
+ */
+
+/*
+ * Bitmap List private functions
+ * Only Bitmap List knows about bitmap directory structure in Qcow2.
+ */
+
+static inline void bitmap_dir_entry_to_cpu(Qcow2BitmapDirEntry *entry)
+{
+    be64_to_cpus(&entry->bitmap_table_offset);
+    be32_to_cpus(&entry->bitmap_table_size);
+    be32_to_cpus(&entry->flags);
+    be16_to_cpus(&entry->name_size);
+    be32_to_cpus(&entry->extra_data_size);
+}
+
+static inline void bitmap_dir_entry_to_be(Qcow2BitmapDirEntry *entry)
+{
+    cpu_to_be64s(&entry->bitmap_table_offset);
+    cpu_to_be32s(&entry->bitmap_table_size);
+    cpu_to_be32s(&entry->flags);
+    cpu_to_be16s(&entry->name_size);
+    cpu_to_be32s(&entry->extra_data_size);
+}
+
+static inline int calc_dir_entry_size(size_t name_size, size_t extra_data_size)
+{
+    return align_offset(sizeof(Qcow2BitmapDirEntry) +
+                        name_size + extra_data_size, 8);
+}
+
+static inline int dir_entry_size(Qcow2BitmapDirEntry *entry)
+{
+    return calc_dir_entry_size(entry->name_size, entry->extra_data_size);
+}
+
+static inline const char *dir_entry_name_field(Qcow2BitmapDirEntry *entry)
+{
+    return (const char *)(entry + 1) + entry->extra_data_size;
+}
+
+static inline char *dir_entry_copy_name(Qcow2BitmapDirEntry *entry)
+{
+    const char *name_field = dir_entry_name_field(entry);
+    return g_strndup(name_field, entry->name_size);
+}
+
+static inline Qcow2BitmapDirEntry *next_dir_entry(Qcow2BitmapDirEntry *entry)
+{
+    return (Qcow2BitmapDirEntry *)((uint8_t *)entry + dir_entry_size(entry));
+}
+
+static int check_dir_entry(BlockDriverState *bs, Qcow2BitmapDirEntry *entry)
+{
+    BDRVQcow2State *s = bs->opaque;
+    uint64_t phys_bitmap_bytes;
+    int64_t len;
+
+    bool fail = (entry->bitmap_table_size == 0) ||
+                (entry->bitmap_table_offset == 0) ||
+                (entry->bitmap_table_offset % s->cluster_size) ||
+                (entry->bitmap_table_size > BME_MAX_TABLE_SIZE) ||
+                (entry->granularity_bits > BME_MAX_GRANULARITY_BITS) ||
+                (entry->granularity_bits < BME_MIN_GRANULARITY_BITS) ||
+                (entry->flags & BME_RESERVED_FLAGS) ||
+                (entry->name_size > BME_MAX_NAME_SIZE) ||
+                (entry->type != BT_DIRTY_TRACKING_BITMAP);
+
+    if (fail) {
+        return -EINVAL;
+    }
+
+    phys_bitmap_bytes = (uint64_t)entry->bitmap_table_size * s->cluster_size;
+    len = bdrv_getlength(bs);
+
+    if (len < 0) {
+        return len;
+    }
+
+    fail = (phys_bitmap_bytes > BME_MAX_PHYS_SIZE) ||
+           (len > ((phys_bitmap_bytes * 8) << entry->granularity_bits));
+
+    return fail ? -EINVAL : 0;
+}
+
+static inline void bitmap_directory_to_be(uint8_t *dir, size_t size)
+{
+    uint8_t *end = dir + size;
+    while (dir < end) {
+        Qcow2BitmapDirEntry *e = (Qcow2BitmapDirEntry *)dir;
+        dir += dir_entry_size(e);
+
+        bitmap_dir_entry_to_be(e);
+    }
+}
+
+/*
+ * Bitmap List public functions
+ */
+
+static void bitmap_free(Qcow2Bitmap *bm)
+{
+    g_free(bm->name);
+    g_free(bm);
+}
+
+static void bitmap_list_free(Qcow2BitmapList *bm_list)
+{
+    Qcow2Bitmap *bm;
+
+    if (bm_list == NULL) {
+        return;
+    }
+
+    while ((bm = QSIMPLEQ_FIRST(bm_list)) != NULL) {
+        QSIMPLEQ_REMOVE_HEAD(bm_list, entry);
+        bitmap_free(bm);
+    }
+
+    g_free(bm_list);
+}
+
+static Qcow2BitmapList *bitmap_list_new(void)
+{
+    Qcow2BitmapList *bm_list = g_new(Qcow2BitmapList, 1);
+    QSIMPLEQ_INIT(bm_list);
+
+    return bm_list;
+}
+
+static uint32_t bitmap_list_count(Qcow2BitmapList *bm_list)
+{
+    Qcow2Bitmap *bm;
+    uint32_t nb_bitmaps = 0;
+
+    QSIMPLEQ_FOREACH(bm, bm_list, entry) {
+        nb_bitmaps++;
+    }
+
+    return nb_bitmaps;
+}
+
+/* bitmap_list_load
+ * Get bitmap list from qcow2 image. Actually reads bitmap directory,
+ * checks it and convert to bitmap list.
+ */
+static Qcow2BitmapList *bitmap_list_load(BlockDriverState *bs, uint64_t offset,
+                                         uint64_t size, Error **errp)
+{
+    int ret;
+    BDRVQcow2State *s = bs->opaque;
+    uint8_t *dir, *dir_end;
+    Qcow2BitmapDirEntry *e;
+    uint32_t nb_dir_entries = 0;
+    Qcow2BitmapList *bm_list = NULL;
+
+    if (size == 0) {
+        error_setg(errp, "Requested bitmap directory size is zero");
+        return NULL;
+    }
+
+    if (size > QCOW2_MAX_BITMAP_DIRECTORY_SIZE) {
+        error_setg(errp, "Requested bitmap directory size is too big");
+        return NULL;
+    }
+
+    dir = g_try_malloc(size);
+    if (dir == NULL) {
+        error_setg(errp, "Failed to allocate space for bitmap directory");
+        return NULL;
+    }
+    dir_end = dir + size;
+
+    ret = bdrv_pread(bs->file, offset, dir, size);
+    if (ret < 0) {
+        error_setg_errno(errp, -ret, "Failed to read bitmap directory");
+        goto fail;
+    }
+
+    bm_list = bitmap_list_new();
+    for (e = (Qcow2BitmapDirEntry *)dir;
+         e < (Qcow2BitmapDirEntry *)dir_end;
+         e = next_dir_entry(e))
+    {
+        Qcow2Bitmap *bm;
+
+        if ((uint8_t *)(e + 1) > dir_end) {
+            goto broken_dir;
+        }
+
+        if (++nb_dir_entries > s->nb_bitmaps) {
+            error_setg(errp, "More bitmaps found than specified in header"
+                       " extension");
+            goto fail;
+        }
+        bitmap_dir_entry_to_cpu(e);
+
+        if ((uint8_t *)next_dir_entry(e) > dir_end) {
+            goto broken_dir;
+        }
+
+        if (e->extra_data_size != 0) {
+            error_setg(errp, "Bitmap extra data is not supported");
+            goto fail;
+        }
+
+        ret = check_dir_entry(bs, e);
+        if (ret < 0) {
+            error_setg(errp, "Bitmap '%.*s' doesn't satisfy the constraints",
+                       e->name_size, dir_entry_name_field(e));
+            goto fail;
+        }
+
+        bm = g_new(Qcow2Bitmap, 1);
+        bm->table_offset = e->bitmap_table_offset;
+        bm->table_size = e->bitmap_table_size;
+        bm->flags = e->flags;
+        bm->granularity_bits = e->granularity_bits;
+        bm->name = dir_entry_copy_name(e);
+        QSIMPLEQ_INSERT_TAIL(bm_list, bm, entry);
+    }
+
+    if (nb_dir_entries != s->nb_bitmaps) {
+        error_setg(errp, "Less bitmaps found than specified in header"
+                         " extension");
+        goto fail;
+    }
+
+    if ((uint8_t *)e != dir_end) {
+        goto broken_dir;
+    }
+
+    g_free(dir);
+    return bm_list;
+
+broken_dir:
+    ret = -EINVAL;
+    error_setg(errp, "Broken bitmap directory");
+
+fail:
+    g_free(dir);
+    bitmap_list_free(bm_list);
+
+    return NULL;
+}
+
+/* bitmap_list_store
+ * Store bitmap list to qcow2 image as a bitmap directory.
+ * Everything is checked.
+ */
+static int bitmap_list_store(BlockDriverState *bs, Qcow2BitmapList *bm_list,
+                             uint64_t *offset, uint64_t *size, bool in_place)
+{
+    int ret;
+    uint8_t *dir;
+    int64_t dir_offset = 0;
+    uint64_t dir_size = 0;
+    Qcow2Bitmap *bm;
+    Qcow2BitmapDirEntry *e;
+
+    QSIMPLEQ_FOREACH(bm, bm_list, entry) {
+        dir_size += calc_dir_entry_size(strlen(bm->name), 0);
+    }
+
+    if (dir_size == 0 || dir_size > QCOW2_MAX_BITMAP_DIRECTORY_SIZE) {
+        return -EINVAL;
+    }
+
+    if (in_place) {
+        if (*size != dir_size || *offset == 0) {
+            return -EINVAL;
+        }
+
+        dir_offset = *offset;
+    }
+
+    dir = g_try_malloc(dir_size);
+    if (dir == NULL) {
+        return -ENOMEM;
+    }
+
+    e = (Qcow2BitmapDirEntry *)dir;
+    QSIMPLEQ_FOREACH(bm, bm_list, entry) {
+        e->bitmap_table_offset = bm->table_offset;
+        e->bitmap_table_size = bm->table_size;
+        e->flags = bm->flags;
+        e->type = BT_DIRTY_TRACKING_BITMAP;
+        e->granularity_bits = bm->granularity_bits;
+        e->name_size = strlen(bm->name);
+        e->extra_data_size = 0;
+        memcpy(e + 1, bm->name, e->name_size);
+
+        if (check_dir_entry(bs, e) < 0) {
+            ret = -EINVAL;
+            goto fail;
+        }
+
+        e = next_dir_entry(e);
+    }
+
+    bitmap_directory_to_be(dir, dir_size);
+
+    if (!in_place) {
+        dir_offset = qcow2_alloc_clusters(bs, dir_size);
+        if (dir_offset < 0) {
+            ret = dir_offset;
+            goto fail;
+        }
+    }
+
+    ret = qcow2_pre_write_overlap_check(bs, 0, dir_offset, dir_size);
+    if (ret < 0) {
+        goto fail;
+    }
+
+    ret = bdrv_pwrite(bs->file, dir_offset, dir, dir_size);
+    if (ret < 0) {
+        goto fail;
+    }
+
+    g_free(dir);
+
+    if (!in_place) {
+        *size = dir_size;
+        *offset = dir_offset;
+    }
+
+    return 0;
+
+fail:
+    g_free(dir);
+
+    if (!in_place && dir_offset > 0) {
+        qcow2_free_clusters(bs, dir_offset, dir_size, QCOW2_DISCARD_OTHER);
+    }
+
+    return ret;
+}
+
+/*
+ * Bitmap List end
+ */
+
+static int update_ext_header_and_dir_in_place(BlockDriverState *bs,
+                                              Qcow2BitmapList *bm_list)
+{
+    BDRVQcow2State *s = bs->opaque;
+    int ret;
+
+    if (!(s->autoclear_features & QCOW2_AUTOCLEAR_BITMAPS) ||
+        bm_list == NULL || QSIMPLEQ_EMPTY(bm_list) ||
+        bitmap_list_count(bm_list) != s->nb_bitmaps)
+    {
+        return -EINVAL;
+    }
+
+    s->autoclear_features &= ~(uint64_t)QCOW2_AUTOCLEAR_BITMAPS;
+    ret = update_header_sync(bs);
+    if (ret < 0) {
+        return ret;
+    }
+
+    /* autoclear bit is not set, so we can safely update bitmap directory */
+
+    ret = bitmap_list_store(bs, bm_list, &s->bitmap_directory_offset,
+                            &s->bitmap_directory_size, true);
+    if (ret < 0) {
+        /* autoclear bit is cleared, so all leaked clusters would be removed on
+         * qemu-img check */
+        return ret;
+    }
+
+    s->autoclear_features |= QCOW2_AUTOCLEAR_BITMAPS;
+    return update_header_sync(bs);
+}
+
+/* for g_slist_foreach for GSList of BdrvDirtyBitmap* elements */
+static void release_dirty_bitmap_helper(gpointer bitmap,
+                                        gpointer bs)
+{
+    bdrv_release_dirty_bitmap(bs, bitmap);
+}
+
+void qcow2_load_autoloading_dirty_bitmaps(BlockDriverState *bs, Error **errp)
+{
+    BDRVQcow2State *s = bs->opaque;
+    Qcow2BitmapList *bm_list;
+    Qcow2Bitmap *bm;
+    GSList *created_dirty_bitmaps = NULL;
+
+    if (s->nb_bitmaps == 0) {
+        /* No bitmaps - nothing to do */
+        return;
+    }
+
+    bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
+                               s->bitmap_directory_size, errp);
+    if (bm_list == NULL) {
+        return;
+    }
+
+    QSIMPLEQ_FOREACH(bm, bm_list, entry) {
+        if ((bm->flags & BME_FLAG_AUTO) && !(bm->flags & BME_FLAG_IN_USE)) {
+            BdrvDirtyBitmap *bitmap = load_bitmap(bs, bm, errp);
+            if (bitmap == NULL) {
+                goto fail;
+            }
+            bm->flags |= BME_FLAG_IN_USE;
+            created_dirty_bitmaps =
+                    g_slist_append(created_dirty_bitmaps, bitmap);
+        }
+    }
+
+    if (created_dirty_bitmaps != NULL && can_write(bs)) {
+        /* in_use flags must be updated */
+        int ret = update_ext_header_and_dir_in_place(bs, bm_list);
+        if (ret < 0) {
+            error_setg(errp, "Can't update bitmap directory");
+            goto fail;
+        }
+    }
+
+    g_slist_free(created_dirty_bitmaps);
+    bitmap_list_free(bm_list);
+
+    return;
+
+fail:
+    g_slist_foreach(created_dirty_bitmaps, release_dirty_bitmap_helper, bs);
+    g_slist_free(created_dirty_bitmaps);
+    bitmap_list_free(bm_list);
+}
diff --git a/block/qcow2.c b/block/qcow2.c
index a8835988c7..9f64753138 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -3540,6 +3540,8 @@ BlockDriver bdrv_qcow2 = {
 
     .bdrv_detach_aio_context  = qcow2_detach_aio_context,
     .bdrv_attach_aio_context  = qcow2_attach_aio_context,
+
+    .bdrv_load_autoloading_dirty_bitmaps = 
qcow2_load_autoloading_dirty_bitmaps,
 };
 
 static void bdrv_qcow2_init(void)
diff --git a/block/qcow2.h b/block/qcow2.h
index 861b5011dd..bcedf5bdf2 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -613,4 +613,7 @@ int qcow2_cache_get_empty(BlockDriverState *bs, Qcow2Cache 
*c, uint64_t offset,
     void **table);
 void qcow2_cache_put(BlockDriverState *bs, Qcow2Cache *c, void **table);
 
+/* qcow2-bitmap.c functions */
+void qcow2_load_autoloading_dirty_bitmaps(BlockDriverState *bs, Error **errp);
+
 #endif
-- 
2.11.0