Commit cdeaf1f1 authored by Fam Zheng's avatar Fam Zheng Committed by Stefan Hajnoczi
Browse files

vmdk: add bdrv_co_write_zeroes 



Use special offset to write zeroes efficiently, when zeroed-grain GTE is
available. If zero-write an allocated cluster, cluster is leaked because
its offset pointer is overwritten by "0x1".

Signed-off-by: default avatarFam Zheng <famz@redhat.com>
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent e304e8e5

block/vmdk.c

+68 −18
Original line number Diff line number Diff line
@@ -124,6 +124,7 @@ typedef struct VmdkMetaData { 
    unsigned int l2_index;

    unsigned int l2_offset;

    int valid;

    uint32_t *l2_cache_entry;

} VmdkMetaData;



typedef struct VmdkGrainMarker {
@@ -835,6 +836,9 @@ static int vmdk_L2update(VmdkExtent *extent, VmdkMetaData *m_data) 
            return VMDK_ERROR;

        }

    }

    if (m_data->l2_cache_entry) {

        *m_data->l2_cache_entry = offset;

    }



    return VMDK_OK;

}
@@ -905,6 +909,14 @@ static int get_cluster_offset(BlockDriverState *bs, 
    l2_index = ((offset >> 9) / extent->cluster_sectors) % extent->l2_size;

    *cluster_offset = le32_to_cpu(l2_table[l2_index]);



    if (m_data) {

        m_data->valid = 1;

        m_data->l1_index = l1_index;

        m_data->l2_index = l2_index;

        m_data->offset = *cluster_offset;

        m_data->l2_offset = l2_offset;

        m_data->l2_cache_entry = &l2_table[l2_index];

    }

    if (extent->has_zero_grain && *cluster_offset == VMDK_GTE_ZEROED) {

        zeroed = true;

    }
@@ -938,10 +950,6 @@ static int get_cluster_offset(BlockDriverState *bs, 


        if (m_data) {

            m_data->offset = *cluster_offset;

            m_data->l1_index = l1_index;

            m_data->l2_index = l2_index;

            m_data->l2_offset = l2_offset;

            m_data->valid = 1;

        }

    }

    *cluster_offset <<= 9;
@@ -1164,8 +1172,17 @@ static coroutine_fn int vmdk_co_read(BlockDriverState *bs, int64_t sector_num, 
    return ret;

}



/**

 * vmdk_write:

 * @zeroed:       buf is ignored (data is zero), use zeroed_grain GTE feature

 * if possible, otherwise return -ENOTSUP.

 * @zero_dry_run: used for zeroed == true only, don't update L2 table, just

 *

 * Returns: error code with 0 for success.

 */

static int vmdk_write(BlockDriverState *bs, int64_t sector_num,

                     const uint8_t *buf, int nb_sectors)

                      const uint8_t *buf, int nb_sectors,

                      bool zeroed, bool zero_dry_run)

{

    BDRVVmdkState *s = bs->opaque;

    VmdkExtent *extent = NULL;
@@ -1211,7 +1228,7 @@ static int vmdk_write(BlockDriverState *bs, int64_t sector_num, 
                                        &cluster_offset);

            }

        }

        if (ret) {

        if (ret == VMDK_ERROR) {

            return -EINVAL;

        }

        extent_begin_sector = extent->end_sector - extent->sectors;
@@ -1221,7 +1238,23 @@ static int vmdk_write(BlockDriverState *bs, int64_t sector_num, 
        if (n > nb_sectors) {

            n = nb_sectors;

        }



        if (zeroed) {

            /* Do zeroed write, buf is ignored */

            if (extent->has_zero_grain &&

                    index_in_cluster == 0 &&

                    n >= extent->cluster_sectors) {

                n = extent->cluster_sectors;

                if (!zero_dry_run) {

                    m_data.offset = VMDK_GTE_ZEROED;

                    /* update L2 tables */

                    if (vmdk_L2update(extent, &m_data) != VMDK_OK) {

                        return -EIO;

                    }

                }

            } else {

                return -ENOTSUP;

            }

        } else {

            ret = vmdk_write_extent(extent,

                            cluster_offset, index_in_cluster * 512,

                            buf, n, sector_num);
@@ -1230,10 +1263,11 @@ static int vmdk_write(BlockDriverState *bs, int64_t sector_num, 
            }

            if (m_data.valid) {

                /* update L2 tables */

            if (vmdk_L2update(extent, &m_data) == -1) {

                if (vmdk_L2update(extent, &m_data) != VMDK_OK) {

                    return -EIO;

                }

            }

        }

        nb_sectors -= n;

        sector_num += n;

        buf += n * 512;
@@ -1257,7 +1291,22 @@ static coroutine_fn int vmdk_co_write(BlockDriverState *bs, int64_t sector_num, 
    int ret;

    BDRVVmdkState *s = bs->opaque;

    qemu_co_mutex_lock(&s->lock);

    ret = vmdk_write(bs, sector_num, buf, nb_sectors);

    ret = vmdk_write(bs, sector_num, buf, nb_sectors, false, false);

    qemu_co_mutex_unlock(&s->lock);

    return ret;

}



static int coroutine_fn vmdk_co_write_zeroes(BlockDriverState *bs,

                                             int64_t sector_num,

                                             int nb_sectors)

{

    int ret;

    BDRVVmdkState *s = bs->opaque;

    qemu_co_mutex_lock(&s->lock);

    ret = vmdk_write(bs, sector_num, NULL, nb_sectors, true, true);

    if (!ret) {

        ret = vmdk_write(bs, sector_num, NULL, nb_sectors, true, false);

    }

    qemu_co_mutex_unlock(&s->lock);

    return ret;

}
@@ -1737,6 +1786,7 @@ static BlockDriver bdrv_vmdk = { 
    .bdrv_reopen_prepare = vmdk_reopen_prepare,

    .bdrv_read      = vmdk_co_read,

    .bdrv_write     = vmdk_co_write,

    .bdrv_co_write_zeroes = vmdk_co_write_zeroes,

    .bdrv_close     = vmdk_close,

    .bdrv_create    = vmdk_create,

    .bdrv_co_flush_to_disk  = vmdk_co_flush,