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Re: [Qemu-block] [Qemu-devel] Subject: [PATCH] qcow2 resize with snapsho
From: |
Gonglei |
Subject: |
Re: [Qemu-block] [Qemu-devel] Subject: [PATCH] qcow2 resize with snapshot, mod |
Date: |
Fri, 2 Sep 2016 18:33:27 +0800 |
User-agent: |
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.4.0 |
Hi,
You should change your patch's commit message to show what your patch solved.
Please refer to the guide:
http://wiki.qemu.org/Contribute/SubmitAPatch
Regards,
-Gonglei
On 2016/9/2 14:41, zhangzhiming wrote:
> ping
>
> zhangzhiming
> address@hidden
>
>
>
>> On Aug 15, 2016, at 7:56 PM, zhangzhiming <address@hidden> wrote:
>>
>> hi, i modified my code by Kevin Wolf’s review. and thanks for review again.
>>
>>
>>
>> Signed-off-by: zhangzhiming <address@hidden>
>> ---
>> block.c | 19 ----------------
>> block/qcow2-cluster.c | 55
>> ++++++++++++++++++++++++++++++++++--------------
>> block/qcow2-snapshot.c | 34 ++++++++++++++--------------
>> block/qcow2.c | 2 +-
>> block/qcow2.h | 2 +-
>> 5 files changed, 58 insertions(+), 54 deletions(-)
>>
>> diff --git a/block.c b/block.c
>> index 0de7b2d..f54bc25 100644
>> --- a/block.c
>> +++ b/block.c
>> @@ -2586,25 +2586,6 @@ int bdrv_truncate(BlockDriverState *bs, int64_t
>> offset)
>> return ret;
>> }
>>
>> -int bdrv_apply_snapshot(BlockDriverState *bs, const char *snapshot_id,
>> - uint64_t snapshot_size)
>> -{
>> - int ret = bdrv_snapshot_goto(bs, snapshot_id);
>> - if (ret < 0) {
>> - return ret;
>> - }
>> -
>> - ret = refresh_total_sectors(bs, snapshot_size >> BDRV_SECTOR_BITS);
>> - if (ret < 0) {
>> - return ret;
>> - }
>> - bdrv_dirty_bitmap_truncate(bs);
>> - if (bs->blk) {
>> - blk_dev_resize_cb(bs->blk);
>> - }
>> - return ret;
>> -}
>> -
>> /**
>> * Length of a allocated file in bytes. Sparse files are counted by actual
>> * allocated space. Return < 0 if error or unknown.
>> diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
>> index ebadddf..2190528 100644
>> --- a/block/qcow2-cluster.c
>> +++ b/block/qcow2-cluster.c
>> @@ -32,32 +32,55 @@
>> #include "qemu/bswap.h"
>> #include "trace.h"
>>
>> -int shrink_l1_table(BlockDriverState *bs, int64_t new_l1_size)
>> +static int free_some_l2_table(BlockDriverState *bs, int64_t old_size,
>> + int64_t new_size)
>> {
>> BDRVQcow2State *s = bs->opaque;
>> - int64_t old_l1_size = s->l1_size;
>> - s->l1_size = new_l1_size;
>> - int ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset,
>> - s->l1_size, 1);
>> - if (ret < 0) {
>> - return ret;
>> + int old_l1_size = size_to_l1(s, old_size);
>> + int new_l1_size = size_to_l1(s, new_size);
>> + if (old_l1_size == new_l1_size) {
>> + return 0;
>> }
>> + int i;
>> + for (i = new_l1_size; i < old_l1_size; i++) {
>> + uint64_t l2_offset = s->l1_table[i] & L1E_OFFSET_MASK;
>> + qcow2_free_clusters(bs, l2_offset, s->cluster_size,
>> + QCOW2_DISCARD_OTHER);
>> + s->l1_table[i] = 0;
>> + /* write l1 entry will be called for several times and
>> + * because l1 is short, i think is tolerated! */
>> + qcow2_write_l1_entry(bs, i);
>> + }
>> + return 0;
>> +}
>>
>> - s->l1_size = old_l1_size;
>> - ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset,
>> - s->l1_size, -1);
>> +int shrink_disk(BlockDriverState *bs, int64_t new_size)
>> +{
>> + BDRVQcow2State *s = bs->opaque;
>> + int64_t old_size = bs->total_sectors * 512;
>> + int64_t new_sector_nb = DIV_ROUND_UP(new_size, 512);
>> + int64_t discard_sectors_nb = bs->total_sectors - new_sector_nb;
>> + int64_t old_cluster_nb = DIV_ROUND_UP(old_size, s->cluster_size);
>> + int64_t new_cluster_nb = DIV_ROUND_UP(new_size, s->cluster_size);
>> + if (old_cluster_nb == new_cluster_nb) {
>> + return 0;
>> + }
>> + s->l1_size = size_to_l1(s, new_size);
>> + bs->total_sectors = new_sector_nb;
>> + int ret = qcow2_update_header(bs);
>> if (ret < 0) {
>> + s->l1_size = size_to_l1(s, old_size);
>> + bs->total_sectors = old_size / 512;
>> return ret;
>> }
>> - s->l1_size = new_l1_size;
>>
>> - uint32_t be_l1_size = cpu_to_be32(s->l1_size);
>> - ret = bdrv_pwrite_sync(bs->file->bs, offsetof(QCowHeader, l1_size),
>> - &be_l1_size, sizeof(be_l1_size));
>> + /* can't be undone here, if failed nothing will be done */
>> + ret = qcow2_discard_clusters(bs, new_size, discard_sectors_nb,
>> + QCOW2_DISCARD_OTHER, true);
>> if (ret < 0) {
>> - return ret;
>> + return 0;
>> }
>> -
>> + free_some_l2_table(bs, old_size, new_size);
>> return 0;
>> }
>>
>> diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c
>> index 6dd6769..40a0d26 100644
>> --- a/block/qcow2-snapshot.c
>> +++ b/block/qcow2-snapshot.c
>> @@ -490,6 +490,7 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const char
>> *snapshot_id)
>>
>> cur_l1_bytes = s->l1_size * sizeof(uint64_t);
>> sn_l1_bytes = sn->l1_size * sizeof(uint64_t);
>> + int max_l1_size_bytes = MAX(sn_l1_bytes, cur_l1_bytes);
>>
>> /*
>> * Copy the snapshot L1 table to the current L1 table.
>> @@ -499,7 +500,7 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const char
>> *snapshot_id)
>> * Decrease the refcount referenced by the old one only when the L1
>> * table is overwritten.
>> */
>> - sn_l1_table = g_try_malloc0(sn_l1_bytes);
>> + sn_l1_table = g_try_malloc0(max_l1_size_bytes);
>> if (sn_l1_bytes && sn_l1_table == NULL) {
>> ret = -ENOMEM;
>> goto fail;
>> @@ -517,34 +518,32 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const
>> char *snapshot_id)
>> goto fail;
>> }
>>
>> - ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_ACTIVE_L1,
>> - s->l1_table_offset, sn_l1_bytes);
>> - if (ret < 0) {
>> - goto fail;
>> - }
>> -
>> - ret = bdrv_pwrite_sync(bs->file->bs, s->l1_table_offset, sn_l1_table,
>> - sn_l1_bytes);
>> + /* update meta data first, for failed */
>> + int old_l1_size = s->l1_size;
>> + uint64_t old_total_sectors = bs->total_sectors;
>> + bs->total_sectors = sn->disk_size / BDRV_SECTOR_SIZE;
>> + s->l1_size = sn->l1_size;
>> + ret = qcow2_update_header(bs);
>> if (ret < 0) {
>> + s->l1_size = old_l1_size;
>> + bs->total_sectors = old_total_sectors;
>> goto fail;
>> }
>>
>> - /* write updated header.size */
>> - uint64_t be_disk_size = cpu_to_be64(sn->disk_size);
>> - ret = bdrv_pwrite_sync(bs->file->bs, offsetof(QCowHeader, size),
>> - &be_disk_size, sizeof(uint64_t));
>> + /* and then update l1 table */
>> + ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_ACTIVE_L1,
>> + s->l1_table_offset,
>> max_l1_size_bytes);
>> if (ret < 0) {
>> goto fail;
>> }
>>
>> - uint32_t be_l1_size = cpu_to_be32(sn->l1_size);
>> - ret = bdrv_pwrite_sync(bs->file->bs, offsetof(QCowHeader, l1_size),
>> - &be_l1_size, sizeof(be_l1_size));
>> + ret = bdrv_pwrite_sync(bs->file->bs, s->l1_table_offset, sn_l1_table,
>> + max_l1_size_bytes);
>> if (ret < 0) {
>> goto fail;
>> }
>>
>> - s->l1_vm_state_index = sn->l1_size;
>> + s->l1_vm_state_index = size_to_l1(s, sn->disk_size);;
>>
>> /*
>> * Decrease refcount of clusters of current L1 table.
>> @@ -556,6 +555,7 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const char
>> *snapshot_id)
>> * the in-memory data instead of really using the offset to load a new
>> one,
>> * which is why this works.
>> */
>> + s->l1_size = old_l1_size;
>> ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset,
>> s->l1_size, -1);
>>
>> diff --git a/block/qcow2.c b/block/qcow2.c
>> index 612a534..01a66f2 100644
>> --- a/block/qcow2.c
>> +++ b/block/qcow2.c
>> @@ -2513,7 +2513,7 @@ static int qcow2_truncate(BlockDriverState *bs,
>> int64_t offset)
>>
>> new_l1_size = size_to_l1(s, offset);
>> if (offset < bs->total_sectors * 512) {
>> - ret = shrink_l1_table(bs, new_l1_size);
>> + ret = shrink_disk(bs, offset);
>> if (ret < 0) {
>> return ret;
>> }
>> diff --git a/block/qcow2.h b/block/qcow2.h
>> index 8efa735..ba622b6 100644
>> --- a/block/qcow2.h
>> +++ b/block/qcow2.h
>> @@ -534,7 +534,7 @@ int qcow2_change_refcount_order(BlockDriverState *bs,
>> int refcount_order,
>> void *cb_opaque, Error **errp);
>>
>> /* qcow2-cluster.c functions */
>> -int shrink_l1_table(BlockDriverState *bs, int64_t new_l1_size);
>> +int shrink_disk(BlockDriverState *bs, int64_t new_size);
>> int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size,
>> bool exact_size);
>> int qcow2_write_l1_entry(BlockDriverState *bs, int l1_index);
>> --
>> 1.7.1
>>
>>
>>
>>
>> zhangzhiming
>> address@hidden
>>
>>
>>
>
>
>
> .
>