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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: Fam Zheng <famz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Fam Zheng 2013-05-02 10:25:27 +08:00 committed by Stefan Hajnoczi
parent e304e8e5a0
commit cdeaf1f159
1 changed files with 68 additions and 18 deletions
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86
block/vmdk.c
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@ -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;
@ -1221,17 +1238,34 @@ static int vmdk_write(BlockDriverState *bs, int64_t sector_num,
if (n > nb_sectors) {
n = nb_sectors;
}
ret = vmdk_write_extent(extent,
cluster_offset, index_in_cluster * 512,
buf, n, sector_num);
if (ret) {
return ret;
}
if (m_data.valid) {
/* update L2 tables */
if (vmdk_L2update(extent, &m_data) == -1) {
return -EIO;
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);
if (ret) {
return ret;
}
if (m_data.valid) {
/* update L2 tables */
if (vmdk_L2update(extent, &m_data) != VMDK_OK) {
return -EIO;
}
}
}
nb_sectors -= n;
@ -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,