[Qemu-devel] DROP THIS Re: [PATCH 11/22] qcow2-bitmap: add qcow2_store_persistent_bitmaps()

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

Sorry, this was an accidental reply.

On 17.10.2016 20:57, Vladimir Sementsov-Ogievskiy wrote:
> On 30.09.2016 12:53, Vladimir Sementsov-Ogievskiy wrote:
>> Realize block bitmap stroing interface, to allow qcow2 images store
>> persistent bitmaps.
>>
>> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>> ---
>>  block/qcow2-bitmap.c | 241 
>> +++++++++++++++++++++++++++++++++++++++++++++++++++
>>  block/qcow2.c        |   2 +
>>  block/qcow2.h        |   2 +
>>  3 files changed, 245 insertions(+)
>>
>> diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c
>> index 81520cd..a5be25a 100644
>> --- a/block/qcow2-bitmap.c
>> +++ b/block/qcow2-bitmap.c
>> @@ -27,6 +27,7 @@
>>
>>  #include "qemu/osdep.h"
>>  #include "qapi/error.h"
>> +#include "qemu/cutils.h"
>>
>>  #include "block/block_int.h"
>>  #include "block/qcow2.h"
>> @@ -96,6 +97,15 @@ static inline void bitmap_table_to_cpu(uint64_t 
>> *bitmap_table, size_t size)
>>      }
>>  }
>>
>> +static inline void bitmap_table_to_be(uint64_t *bitmap_table, size_t 
>> size)
>> +{
>> +    size_t i;
>> +
>> +    for (i = 0; i < size; ++i) {
>> +        cpu_to_be64s(&bitmap_table[i]);
>> +    }
>> +}
>> +
>>  static inline int calc_dir_entry_size(size_t name_size, size_t 
>> extra_data_size)
>>  {
>>      return align_offset(sizeof(Qcow2BitmapDirEntry) +
>> @@ -564,3 +574,234 @@ out:
>>
>>      return ret;
>>  }
>> +
>> +/* store_bitmap_data()
>> + * Store bitmap to image, filling bitamp table accordingly.
>
>
>> + */
>> +static int store_bitmap_data(BlockDriverState *bs, BdrvDirtyBitmap 
>> *bitmap,
>> +                             uint64_t *bitmap_table, uint32_t 
>> bitmap_table_size)
>> +{
>> +    int ret;
>> +    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 tb_size =
>> +            size_to_clusters(s,
>> +                bdrv_dirty_bitmap_serialization_size(bitmap, 0, 
>> bm_size));
>
>
>> +
>> +    BdrvDirtyBitmapIter *dbi;
>> +
>> +    if (tb_size != bitmap_table_size) {
>> +        return -EINVAL;
>> +    }
>> +
>> +    memset(bitmap_table, 0, bitmap_table_size * 
>> sizeof(bitmap_table[0]));
>
>
>> +
>> +    dbi = bdrv_dirty_iter_new(bitmap, 0);
>> +    buf = g_malloc(cl_size);
>> +    dsc = dirty_sectors_in_cluster(s, bitmap);
>> +
>> +    while ((sector = bdrv_dirty_iter_next(dbi)) != -1) {
>
>
>> +        uint64_t cluster = sector / dsc;
>> +        sector = cluster * dsc;
>
>
>
>> +        uint64_t end = MIN(bm_size, sector + dsc);
>> +        uint64_t write_size =
>> +            bdrv_dirty_bitmap_serialization_size(bitmap, sector, end 
>> - sector);
>> +
>> +        int64_t off = qcow2_alloc_clusters(bs, cl_size);
>> +        if (off < 0) {
>> +            ret = off;
>> +            goto finish;
>> +        }
>> +        bitmap_table[cluster] = off;
>> +
>> +        bdrv_dirty_bitmap_serialize_part(bitmap, buf, sector, end);
>
>
>
>> +        if (write_size < cl_size) {
>> +            memset(buf + write_size, 0, cl_size - write_size);
>> +        }
>> +
>
>
>> +        ret = bdrv_pwrite(bs->file, off, buf, cl_size);
>> +        if (ret < 0) {
>> +            goto finish;
>> +        }
>> +
>> +        if (end >= bm_size) {
>> +            break;
>> +        }
>> +
>> +        bdrv_set_dirty_iter(dbi, end);
>> +    }
>> +    ret = 0; /* writes */
>
> What is that comment supposed to mean?
>
>> +
>> +finish:
>> +    if (ret < 0) {
>> +        clear_bitmap_table(bs, bitmap_table, bitmap_table_size);
>> +    }
>> +    g_free(buf);
>> +    bdrv_dirty_iter_free(dbi);
>> +
>> +    return ret;
>
> In case you decide to keep BME_MAX_PHYS_SIZE, this function should check
> somewhere that the physical size of the bitmap does not exceed that 
> value.
>
>> +}
>> +
>> +/* store_bitmap()
>> + * Store bitmap to qcow2 and set bitmap_table. bitmap_table itself 
>> is not
>> + * stored to qcow2.
>
> First of all, there is no parameter called "bitmap_table", and second,
> yes, the bitmap table is written to the qcow2 file.
>
>> + */
>> +static int store_bitmap(BlockDriverState *bs,
>> +                        BdrvDirtyBitmap *bitmap,
>> +                        Qcow2BitmapDirEntry *entry)
>> +{
>> +    int ret;
>> +    BDRVQcow2State *s = bs->opaque;
>> +    uint64_t bm_size = bdrv_dirty_bitmap_size(bitmap);
>> +    const char *bm_name = bdrv_dirty_bitmap_name(bitmap);
>> +
>> +    uint64_t *tb;
>> +    int64_t tb_offset;
>> +    uint32_t tb_size =
>> +            size_to_clusters(s,
>> +                bdrv_dirty_bitmap_serialization_size(bitmap, 0, 
>> bm_size));
>
> As above, this variable should be of type uint64_t.
>
> Also, you have to check that it does not exceed BME_MAX_TABLE_SIZE.
>
>> +
>> +    tb = g_try_new(uint64_t, tb_size);
>> +    if (tb == NULL) {
>> +        return -ENOMEM;
>> +    }
>> +
>> +    ret = store_bitmap_data(bs, bitmap, tb, tb_size);
>> +    if (ret < 0) {
>> +        g_free(tb);
>> +        return ret;
>> +    }
>> +
>> +    tb_offset = qcow2_alloc_clusters(bs, tb_size * sizeof(tb[0]));
>
> If you don't limit tb_size, then this multiplication can overflow on 32
> bit machines.
>
>> +    if (tb_offset < 0) {
>> +        ret = tb_offset;
>> +        goto fail;
>> +    }
>> +
>
> There should be a metadata overlap check here.
>
>> +    bitmap_table_to_be(tb, tb_size);
>> +    ret = bdrv_pwrite(bs->file, tb_offset, tb, tb_size * 
>> sizeof(tb[0]));
>> +    if (ret < 0) {
>> +        goto fail;
>> +    }
>> +
>> +    g_free(tb);
>> +
>> +    entry->bitmap_table_offset = tb_offset;
>> +    entry->bitmap_table_size = tb_size;
>> +    entry->flags = bdrv_dirty_bitmap_granularity(bitmap) ? 
>> BME_FLAG_AUTO : 0;
>
> s/granularity/get_autoload/
>
>> +    entry->type = BT_DIRTY_TRACKING_BITMAP;
>> +    entry->granularity_bits = 
>> ctz32(bdrv_dirty_bitmap_granularity(bitmap));
>
> You should probably check somewhere that the resulting value for
> entry->granularity_bits is in the BME_{MIN,MAX}_GRANULARITY_BITS range.
>
>> +    entry->name_size = strlen(bm_name);
>
> And that this length does not exceed BME_MAX_NAME_SIZE.
>
>> +    entry->extra_data_size = 0;
>> +    memcpy(entry + 1, bm_name, entry->name_size);
>> +
>> +    return 0;
>> +
>> +fail:
>> +    clear_bitmap_table(bs, tb, tb_size);
>> +
>> +    if (tb_offset > 0) {
>> +        qcow2_free_clusters(bs, tb_offset, tb_size, 
>> QCOW2_DISCARD_ALWAYS);
>
> As before, I'd vote for QCOW2_DISCARD_OTHER.
>
>> +    }
>> +
>> +    g_free(tb);
>> +
>> +    return ret;
>> +}
>> +
>> +static Qcow2BitmapDirEntry *find_bitmap_by_name(uint8_t 
>> *bitmap_directory,
>> +                                                size_t size, const 
>> char *name)
>> +{
>> +    Qcow2BitmapDirEntry *e;
>> +
>> +    for_each_bitmap_dir_entry(e, bitmap_directory, size) {
>> +        if (strncmp((char *)(e + 1), name, e->name_size) == 0) {
>> +            return e;
>> +        }
>> +    }
>> +
>> +    return NULL;
>> +}
>> +
>> +void qcow2_store_persistent_bitmaps(BlockDriverState *bs, Error **errp)
>> +{
>> +    BdrvDirtyBitmap *bm;
>> +    BDRVQcow2State *s = bs->opaque;
>> +    uint32_t new_nb_bitmaps = s->nb_bitmaps;
>> +    uint64_t new_dir_size = s->bitmap_directory_size;
>> +    uint8_t *dir = NULL, *new_dir = NULL;
>> +    int ret;
>> +    Qcow2BitmapDirEntry *new_pos;
>> +
>> +    if (s->nb_bitmaps > 0) {
>> +        dir = directory_read(bs, s->bitmap_directory_offset,
>> +                             s->bitmap_directory_size, errp);
>> +        if (dir == NULL) {
>> +            goto out;
>> +        }
>> +    }
>> +
>> +    for (bm = bdrv_dirty_bitmap_next(bs, NULL); bm != NULL;
>> +            bm = bdrv_dirty_bitmap_next(bs, bm)) {
>> +        const char *name = bdrv_dirty_bitmap_name(bm);
>> +
>> +        if (!bdrv_dirty_bitmap_get_persistance(bm)) {
>> +            continue;
>> +        }
>> +
>> +        if (s->nb_bitmaps > 0 &&
>> +                find_bitmap_by_name(dir, s->bitmap_directory_size, 
>> name)) {
>> +            error_setg(errp,
>> +                       "Can't store bitmap '%s' to '%s', as it 
>> already exists",
>> +                       name, bdrv_get_device_or_node_name(bs));
>> +            goto out;
>> +        }
>> +
>> +        new_nb_bitmaps++;
>> +        new_dir_size += calc_dir_entry_size(strlen(name), 0);
>> +    }
>> +
>> +    if (s->nb_bitmaps == new_nb_bitmaps) {
>> +        /* No new bitmaps - nothing to do */
>> +        goto out;
>> +    }
>> +
>> +    new_dir = g_try_malloc0(new_dir_size);
>> +    if (new_dir == NULL) {
>> +        error_setg(errp, "Can't allocate space for bitmap directory.");
>> +        goto out;
>> +    }
>> +
>> +    memcpy(new_dir, dir, s->bitmap_directory_size);
>> +    new_pos = (Qcow2BitmapDirEntry *)(new_dir + 
>> s->bitmap_directory_size);
>> +
>> +    for (bm = bdrv_dirty_bitmap_next(bs, NULL); bm != NULL;
>> +            bm = bdrv_dirty_bitmap_next(bs, bm)) {
>> +        if (!bdrv_dirty_bitmap_get_persistance(bm)) {
>> +            continue;
>> +        }
>> +
>> +        ret = store_bitmap(bs, bm, new_pos);
>> +        if (ret < 0) {
>> +            error_setg_errno(errp, -ret, "Can't store bitmap '%s' to 
>> '%s'",
>> +                             bdrv_dirty_bitmap_name(bm),
>> +                             bdrv_get_device_or_node_name(bs));
>> +            goto out;
>> +        }
>> +        new_pos = next_dir_entry(new_pos);
>> +    }
>> +
>> +    ret = directory_update(bs, new_dir, new_dir_size, new_nb_bitmaps);
>> +    if (ret < 0) {
>> +        error_setg_errno(errp, -ret, "Can't update bitmap directory 
>> in '%s'",
>> +                         bdrv_get_device_or_node_name(bs));
>> +        goto out;
>> +    }
>> +
>> +out:
>> +    g_free(new_dir);
>> +    g_free(dir);
>
> This error path leaks all the bitmaps that have been written
> successfully (if any). I guess this is more or less fine if
> directory_update() failed (because you can't really tell the state of
> the image header after directory_update(), so better be safe) but it's
> not so fine if just some store_bitmap() failed.
>
> Max
>
>> +}
>> diff --git a/block/qcow2.c b/block/qcow2.c
>> index 02ec224..8238205 100644
>> --- a/block/qcow2.c
>> +++ b/block/qcow2.c
>> @@ -3493,6 +3493,8 @@ BlockDriver bdrv_qcow2 = {
>>
>>      .bdrv_detach_aio_context  = qcow2_detach_aio_context,
>>      .bdrv_attach_aio_context  = qcow2_attach_aio_context,
>> +
>> +    .bdrv_store_persistent_bitmaps = qcow2_store_persistent_bitmaps,
>>  };
>>
>>  static void bdrv_qcow2_init(void)
>> diff --git a/block/qcow2.h b/block/qcow2.h
>> index 482a29f..dfcf4c6 100644
>> --- a/block/qcow2.h
>> +++ b/block/qcow2.h
>> @@ -627,4 +627,6 @@ int qcow2_cache_get_empty(BlockDriverState *bs, 
>> Qcow2Cache *c, uint64_t offset,
>>      void **table);
>>  void qcow2_cache_put(BlockDriverState *bs, Qcow2Cache *c, void 
>> **table);
>>
>> +void qcow2_store_persistent_bitmaps(BlockDriverState *bs, Error 
>> **errp);
>> +
>>  #endif
>>
>
>
>


-- 
Best regards,
Vladimir