Re: [PATCH v2 10/20] parallels: Add dirty bitmaps saving

[Mike Maslenkin]

On Thu, Oct 19, 2023 at 4:05 PM Alexander Ivanov
<alexander.ivanov@virtuozzo.com> wrote:
>
> Now dirty bitmaps can be loaded but there is no their saving. Add code for
> dirty bitmap storage.
>
> Signed-off-by: Alexander Ivanov <alexander.ivanov@virtuozzo.com>
> ---
>  block/parallels-ext.c | 167 ++++++++++++++++++++++++++++++++++++++++++
>  block/parallels.c     |  16 +++-
>  block/parallels.h     |   5 ++
>  3 files changed, 186 insertions(+), 2 deletions(-)
>
> diff --git a/block/parallels-ext.c b/block/parallels-ext.c
> index 8a109f005a..0a632a2331 100644
> --- a/block/parallels-ext.c
> +++ b/block/parallels-ext.c
> @@ -24,6 +24,7 @@
>   */
>
>  #include "qemu/osdep.h"
> +#include "qemu/error-report.h"
>  #include "qapi/error.h"
>  #include "block/block-io.h"
>  #include "block/block_int.h"
> @@ -301,3 +302,169 @@ out:
>
>      return ret;
>  }
> +
> +static void parallels_save_bitmap(BlockDriverState *bs, BdrvDirtyBitmap 
> *bitmap,
> +                                  uint8_t **buf, int *buf_size)
> +{
> +    BDRVParallelsState *s = bs->opaque;
> +    ParallelsFeatureHeader *fh;
> +    ParallelsDirtyBitmapFeature *bh;
> +    uint64_t *l1_table, l1_size, granularity, limit;
> +    int64_t bm_size, ser_size, offset, buf_used;
> +    int64_t alloc_size = 1;
> +    const char *name;
> +    uint8_t *bm_buf;
> +    QemuUUID uuid;
> +    int ret = 0;
> +
> +    if (!bdrv_dirty_bitmap_get_persistence(bitmap) ||
> +        bdrv_dirty_bitmap_inconsistent(bitmap)) {
> +        return;
> +    }
> +
> +    bm_size = bdrv_dirty_bitmap_size(bitmap);
> +    granularity = bdrv_dirty_bitmap_granularity(bitmap);
> +    limit = bdrv_dirty_bitmap_serialization_coverage(s->cluster_size, 
> bitmap);
> +    ser_size = bdrv_dirty_bitmap_serialization_size(bitmap, 0, bm_size);
> +    l1_size = DIV_ROUND_UP(ser_size, s->cluster_size);
> +
> +    buf_used = l1_size * 8 + sizeof(*fh) + sizeof(*bh);
> +    /* Check if there is enough space for the final section */
> +    if (*buf_size - buf_used < sizeof(*fh)) {
> +        return;
> +    }
> +
> +    name = bdrv_dirty_bitmap_name(bitmap);
> +    ret = qemu_uuid_parse(name, &uuid);
> +    if (ret < 0) {
> +        error_report("Can't save dirty bitmap: ID parsing error: '%s'", 
> name);
> +        return;
> +    }
> +
> +    fh = (ParallelsFeatureHeader *)*buf;
> +    bh = (ParallelsDirtyBitmapFeature *)(*buf + sizeof(*fh));
> +    l1_table = (uint64_t *)((uint8_t *)bh + sizeof(*bh));
> +
> +    fh->magic = cpu_to_le64(PARALLELS_DIRTY_BITMAP_FEATURE_MAGIC);
> +    fh->data_size = cpu_to_le32(l1_size * 8 + sizeof(*bh));
> +
> +    bh->l1_size = cpu_to_le32(l1_size);
> +    bh->size = cpu_to_le64(bm_size >> BDRV_SECTOR_BITS);
> +    bh->granularity = cpu_to_le32(granularity >> BDRV_SECTOR_BITS);
> +    memcpy(bh->id, &uuid, sizeof(uuid));
> +
> +    bm_buf = qemu_blockalign(bs, s->cluster_size);
> +
> +    offset = 0;
> +    while ((offset = bdrv_dirty_bitmap_next_dirty(bitmap, offset, bm_size)) 
> >= 0) {
> +        uint64_t idx = offset / limit;
> +        int64_t cluster_off, end, write_size;
> +
> +        offset = QEMU_ALIGN_DOWN(offset, limit);
> +        end = MIN(bm_size, offset + limit);
> +        write_size = bdrv_dirty_bitmap_serialization_size(bitmap, offset,
> +                                                          end - offset);
> +        assert(write_size <= s->cluster_size);
> +
> +        bdrv_dirty_bitmap_serialize_part(bitmap, bm_buf, offset, end - 
> offset);
> +        if (write_size < s->cluster_size) {
> +            memset(bm_buf + write_size, 0, s->cluster_size - write_size);
> +        }
> +
> +        cluster_off = parallels_allocate_host_clusters(bs, &alloc_size);
> +        if (cluster_off <= 0) {
> +            goto end;
> +        }
> +
> +        ret = bdrv_pwrite(bs->file, cluster_off, s->cluster_size, bm_buf, 0);
> +        if (ret < 0) {
> +            memset(&fh->magic, 0, sizeof(fh->magic));
> +            parallels_mark_unused(bs, s->used_bmap, s->used_bmap_size,
> +                                  cluster_off, 1);
> +            goto end;
> +        }
> +
> +        l1_table[idx] = cpu_to_le64(cluster_off >> BDRV_SECTOR_BITS);
> +        offset = end;
> +    }
> +
> +    *buf_size -= buf_used;
> +    *buf += buf_used;
> +
> +end:
> +    qemu_vfree(bm_buf);
> +}
> +
> +void parallels_store_persistent_dirty_bitmaps(BlockDriverState *bs,
> +                                              Error **errp)
> +{
> +    BDRVParallelsState *s = bs->opaque;
> +    BdrvDirtyBitmap *bitmap;
> +    ParallelsFormatExtensionHeader *eh;
> +    int remaining = s->cluster_size;
> +    uint8_t *buf, *pos;
> +    int64_t header_off, alloc_size = 1;
> +    g_autofree uint8_t *hash = NULL;
> +    size_t hash_len = 0;
> +    int ret;
> +
> +    s->header->ext_off = 0;
> +
> +    if (!bdrv_has_named_bitmaps(bs)) {
> +        return;
> +    }
> +
> +    buf = qemu_blockalign0(bs, s->cluster_size);
> +
> +    eh = (ParallelsFormatExtensionHeader *)buf;
> +    pos = buf + sizeof(*eh);
> +
> +    eh->magic = cpu_to_le64(PARALLELS_FORMAT_EXTENSION_MAGIC);
> +
> +    FOR_EACH_DIRTY_BITMAP(bs, bitmap) {
> +        parallels_save_bitmap(bs, bitmap, &pos, &remaining);
> +    }
> +
> +    header_off = parallels_allocate_host_clusters(bs, &alloc_size);
> +    if (header_off < 0) {
> +        error_report("Can't save dirty bitmap: cluster allocation error");
> +        ret = header_off;
> +        goto end;
> +    }
> +
> +    ret = qcrypto_hash_bytes(QCRYPTO_HASH_ALG_MD5,
> +                             (const char *)(buf + sizeof(*eh)),
> +                             s->cluster_size - sizeof(*eh),
> +                             &hash, &hash_len, errp);
> +    if (ret < 0 || hash_len != sizeof(eh->check_sum)) {
> +        error_report("Can't save dirty bitmap: hash error");
> +        ret = -EINVAL;
> +        goto end;
> +    }
> +    memcpy(eh->check_sum, hash, hash_len);
> +
> +    ret = bdrv_pwrite(bs->file, header_off, s->cluster_size, buf, 0);
> +    if (ret < 0) {
> +        error_report("Can't save dirty bitmap: IO error");
> +        parallels_mark_unused(bs, s->used_bmap, s->used_bmap_size,
> +                              header_off, 1);
> +        goto end;
> +    }
> +
> +    s->header->ext_off = cpu_to_le64(header_off / BDRV_SECTOR_SIZE);
> +end:
> +    qemu_vfree(buf);
> +}
> +
> +bool coroutine_fn parallels_co_can_store_new_dirty_bitmap(BlockDriverState 
> *bs,
> +                                                          const char *name,
> +                                                          uint32_t 
> granularity,
> +                                                          Error **errp)
> +{
> +    if (bdrv_find_dirty_bitmap(bs, name)) {
> +        error_setg(errp, "Bitmap already exists: %s", name);
> +        return false;
> +    }
> +
> +    return true;
> +}
> diff --git a/block/parallels.c b/block/parallels.c
> index 2ee2b42038..bb1e765ec8 100644
> --- a/block/parallels.c
> +++ b/block/parallels.c
> @@ -1470,14 +1470,25 @@ fail:
>  static int parallels_inactivate(BlockDriverState *bs)
>  {
>      BDRVParallelsState *s = bs->opaque;
> +    Error *err = NULL;
>      int ret;
>
> +    parallels_store_persistent_dirty_bitmaps(bs, &err);
> +    if (err != NULL) {
> +        error_reportf_err(err, "Lost persistent bitmaps during "
> +                          "inactivation of node '%s': ",
> +                          bdrv_get_device_or_node_name(bs));
> +    }
> +
>      s->header->inuse = 0;
>      parallels_update_header(bs);
>

Recently bdrv_get_device_or_node_name() calls were guarded by
bdrv_graph_rd{,un}lock_main_loop.
There are no annotations for parallels_close() or
parallels_inactivate(), so may be it should be done in the same way?