On Fri, Apr 7, 2017 at 3:08 PM, Fam Zheng <f...@redhat.com> wrote:
> On Thu, 04/06 21:15, jemmy858...@gmail.com wrote:
>> From: Lidong Chen <lidongc...@tencent.com>
>>
>> BLOCK_SIZE is (1 << 20), qcow2 cluster size is 65536 by default,
>> this maybe cause the qcow2 file size is bigger after migration.
>> This patch check each cluster, use blk_pwrite_zeroes for each
>> zero cluster.
>>
>> Signed-off-by: Lidong Chen <lidongc...@tencent.com>
>> ---
>> migration/block.c | 34 ++++++++++++++++++++++++++++++++--
>> 1 file changed, 32 insertions(+), 2 deletions(-)
>>
>> diff --git a/migration/block.c b/migration/block.c
>> index 7734ff7..1fce9b9 100644
>> --- a/migration/block.c
>> +++ b/migration/block.c
>> @@ -885,6 +885,10 @@ static int block_load(QEMUFile *f, void *opaque, int
>> version_id)
>> int64_t total_sectors = 0;
>> int nr_sectors;
>> int ret;
>> + int i;
>> + int cluster_size;
>> + int64_t addr_offset;
>> + uint8_t *buf_offset;
>>
>> do {
>> addr = qemu_get_be64(f);
>> @@ -934,8 +938,34 @@ static int block_load(QEMUFile *f, void *opaque, int
>> version_id)
>> } else {
>> buf = g_malloc(BLOCK_SIZE);
>> qemu_get_buffer(f, buf, BLOCK_SIZE);
>> - ret = blk_pwrite(blk, addr * BDRV_SECTOR_SIZE, buf,
>> - nr_sectors * BDRV_SECTOR_SIZE, 0);
>> +
>> + cluster_size = bdrv_get_cluster_size(blk_bs(blk));
>> +
>> + if (cluster_size > 0) {
>> + for (i = 0; i < BLOCK_SIZE / cluster_size; i++) {
>
> Should we check that cluster_size < BLOCK_SIZE and (BLOCK_SIZE % cluster_size
> ==
> 0)?
I think this is necessary.
Thanks.
>
> Fam
>
>> + addr_offset = addr * BDRV_SECTOR_SIZE
>> + + i * cluster_size;
>> + buf_offset = buf + i * cluster_size;
>> +
>> + if (buffer_is_zero(buf_offset, cluster_size)) {
>> + ret = blk_pwrite_zeroes(blk, addr_offset,
>> + cluster_size,
>> + BDRV_REQ_MAY_UNMAP);
>> + } else {
>> + ret = blk_pwrite(blk, addr_offset,
>> + buf_offset, cluster_size, 0);
>> + }
>> +
>> + if (ret < 0) {
>> + g_free(buf);
>> + return ret;
>> + }
>> + }
>> + } else {
>> + ret = blk_pwrite(blk, addr * BDRV_SECTOR_SIZE, buf,
>> + nr_sectors * BDRV_SECTOR_SIZE, 0);
>> + }
>> +
>> g_free(buf);
>> }
>>
>> --
>> 1.8.3.1
>>
