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Re: [Qemu-devel] [Qemu-block] [PATCH] qcow2 resize with snapshot
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From: |
zhangzhiming |
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Subject: |
Re: [Qemu-devel] [Qemu-block] [PATCH] qcow2 resize with snapshot |
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Date: |
Tue, 7 Jun 2016 16:25:28 +0800 |
hi, need for someone's review of my code. no one does it for nearly one week.
thanks!
zhangzhiming
address@hidden
> On Jun 1, 2016, at 6:24 PM, zhangzhiming <address@hidden> wrote:
>
> hi, here are all changes of my code. thanks for the review!
>
> zhangzhiming
> address@hidden <mailto:address@hidden>
>
> Signed-off-by: zhangzhiming <address@hidden <mailto:address@hidden>>
> ---
> block.c | 19 +++++++++++++++++++
> block/qcow2-cluster.c | 29 +++++++++++++++++++++++++++++
> block/qcow2-snapshot.c | 33 +++++++++++++++++++++++----------
> block/qcow2.c | 29 ++++++++++++++++++++---------
> block/qcow2.h | 1 +
> include/block/snapshot.h | 1 +
> 6 files changed, 93 insertions(+), 19 deletions(-)
>
> diff --git a/block.c b/block.c
> index 18a497f..b6f2004 100644
> --- a/block.c
> +++ b/block.c
> @@ -2631,6 +2631,25 @@ 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 31ecc10..f921fd8 100644
> --- a/block/qcow2-cluster.c
> +++ b/block/qcow2-cluster.c
> @@ -31,6 +31,35 @@
> #include "block/qcow2.h"
> #include "trace.h"
>
> +int shrink_l1_table(BlockDriverState *bs, int64_t new_l1_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;
> + }
> +
> + s->l1_size = old_l1_size;
> + ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset,
> + s->l1_size, -1);
> + if (ret < 0) {
> + 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));
> + if (ret < 0) {
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size,
> bool exact_size)
> {
> diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c
> index 5f4a17e..1ed0e18 100644
> --- a/block/qcow2-snapshot.c
> +++ b/block/qcow2-snapshot.c
> @@ -477,13 +477,6 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const char
> *snapshot_id)
> }
> sn = &s->snapshots[snapshot_index];
>
> - if (sn->disk_size != bs->total_sectors * BDRV_SECTOR_SIZE) {
> - error_report("qcow2: Loading snapshots with different disk "
> - "size is not implemented");
> - ret = -ENOTSUP;
> - goto fail;
> - }
> -
> /*
> * Make sure that the current L1 table is big enough to contain the whole
> * L1 table of the snapshot. If the snapshot L1 table is smaller, the
> @@ -505,7 +498,7 @@ 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(cur_l1_bytes);
> + sn_l1_table = g_try_malloc0(sn_l1_bytes);
> if (cur_l1_bytes && sn_l1_table == NULL) {
> ret = -ENOMEM;
> goto fail;
> @@ -530,11 +523,28 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const
> char *snapshot_id)
> }
>
> ret = bdrv_pwrite_sync(bs->file->bs, s->l1_table_offset, sn_l1_table,
> - cur_l1_bytes);
> + sn_l1_bytes);
> + if (ret < 0) {
> + 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));
> 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));
> + if (ret < 0) {
> + goto fail;
> + }
> +
> + s->l1_vm_state_index = sn->l1_size;
> +
> /*
> * Decrease refcount of clusters of current L1 table.
> *
> @@ -552,7 +562,8 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const char
> *snapshot_id)
> * Now update the in-memory L1 table to be in sync with the on-disk one.
> We
> * need to do this even if updating refcounts failed.
> */
> - for(i = 0;i < s->l1_size; i++) {
> + memset(s->l1_table, 0, s->l1_size * sizeof(uint64_t));
> + for (i = 0; i < sn->l1_size; i++) {
> s->l1_table[i] = be64_to_cpu(sn_l1_table[i]);
> }
>
> @@ -563,6 +574,7 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const char
> *snapshot_id)
> g_free(sn_l1_table);
> sn_l1_table = NULL;
>
> + s->l1_size = sn->l1_size;
> /*
> * Update QCOW_OFLAG_COPIED in the active L1 table (it may have changed
> * when we decreased the refcount of the old snapshot.
> @@ -675,6 +687,7 @@ int qcow2_snapshot_list(BlockDriverState *bs,
> QEMUSnapshotInfo **psn_tab)
> sn_info->date_sec = sn->date_sec;
> sn_info->date_nsec = sn->date_nsec;
> sn_info->vm_clock_nsec = sn->vm_clock_nsec;
> + sn_info->disk_size = sn->disk_size;
> }
> *psn_tab = sn_tab;
> return s->nb_snapshots;
> diff --git a/block/qcow2.c b/block/qcow2.c
> index 62febfc..58b53e1 100644
> --- a/block/qcow2.c
> +++ b/block/qcow2.c
> @@ -2501,22 +2501,33 @@ static int qcow2_truncate(BlockDriverState *bs,
> int64_t offset)
> return -EINVAL;
> }
>
> - /* cannot proceed if image has snapshots */
> - if (s->nb_snapshots) {
> - error_report("Can't resize an image which has snapshots");
> + bool v3_truncate = (s->qcow_version == 3);
> +
> + /* cannot proceed if image has snapshots and qcow_version is not 3 */
> + if (!v3_truncate && s->nb_snapshots) {
> + error_report("Can't resize an image which has snapshots and "
> + "qcow_version is not 3");
> return -ENOTSUP;
> }
>
> - /* shrinking is currently not supported */
> - if (offset < bs->total_sectors * 512) {
> - error_report("qcow2 doesn't support shrinking images yet");
> + /* shrinking is supported from version 3 */
> + if (!v3_truncate && offset < bs->total_sectors * 512) {
> + error_report("qcow2 doesn't support shrinking images yet while"
> + " qcow_version is not 3");
> return -ENOTSUP;
> }
>
> new_l1_size = size_to_l1(s, offset);
> - ret = qcow2_grow_l1_table(bs, new_l1_size, true);
> - if (ret < 0) {
> - return ret;
> + if (offset < bs->total_sectors * 512) {
> + ret = shrink_l1_table(bs, new_l1_size);
> + if (ret < 0) {
> + return ret;
> + }
> + } else {
> + ret = qcow2_grow_l1_table(bs, new_l1_size, true);
> + if (ret < 0) {
> + return ret;
> + }
> }
>
> /* write updated header.size */
> diff --git a/block/qcow2.h b/block/qcow2.h
> index a063a3c..dab9e48 100644
> --- a/block/qcow2.h
> +++ b/block/qcow2.h
> @@ -534,6 +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 qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size,
> bool exact_size);
> int qcow2_write_l1_entry(BlockDriverState *bs, int l1_index);
> diff --git a/include/block/snapshot.h b/include/block/snapshot.h
> index e5c0553..7279c12 100644
> --- a/include/block/snapshot.h
> +++ b/include/block/snapshot.h
> @@ -44,6 +44,7 @@ typedef struct QEMUSnapshotInfo {
> uint32_t date_sec; /* UTC date of the snapshot */
> uint32_t date_nsec;
> uint64_t vm_clock_nsec; /* VM clock relative to boot */
> + uint64_t disk_size;
> } QEMUSnapshotInfo;
>
> int bdrv_snapshot_find(BlockDriverState *bs, QEMUSnapshotInfo *sn_info,
> --
> 1.7.1
>
>
>> On Jun 1, 2016, at 12:15 PM, zhangzhiming <address@hidden
>> <mailto:address@hidden>> wrote:
>>
>> hi, thanks for the review and the format of code changed.
>> have a good day!
>>
>> zhangzhiming
>> address@hidden <mailto:address@hidden>
>>
>> Signed-off-by: zhangzhiming <address@hidden <http://meituan.com/>>
>> ---
>> block.c | 4 ++--
>> block/qcow2-cluster.c | 4 ++--
>> block/qcow2-snapshot.c | 5 ++---
>> block/qcow2.c | 4 ++--
>> 4 files changed, 8 insertions(+), 9 deletions(-)
>>
>> diff --git a/block.c b/block.c
>> index 729f820..b6f2004 100644
>> --- a/block.c
>> +++ b/block.c
>> @@ -2643,9 +2643,9 @@ int bdrv_apply_snapshot(BlockDriverState *bs, const
>> char *snapshot_id,
>> if (ret < 0) {
>> return ret;
>> }
>> - bdrv_dirty_bitmap_truncate(bs); /* void return */
>> + bdrv_dirty_bitmap_truncate(bs);
>> if (bs->blk) {
>> - blk_dev_resize_cb(bs->blk); /* void return too */
>> + blk_dev_resize_cb(bs->blk);
>> }
>> return ret;
>> }
>> diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
>> index e4c5c05..f921fd8 100644
>> --- a/block/qcow2-cluster.c
>> +++ b/block/qcow2-cluster.c
>> @@ -37,14 +37,14 @@ int shrink_l1_table(BlockDriverState *bs, int64_t
>> new_l1_size)
>> 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);
>> + s->l1_size, 1);
>> if (ret < 0) {
>> return ret;
>> }
>>
>> s->l1_size = old_l1_size;
>> ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset,
>> - s->l1_size, -1);
>> + s->l1_size, -1);
>> if (ret < 0) {
>> return ret;
>> }
>> diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c
>> index 9c77096..1ed0e18 100644
>> --- a/block/qcow2-snapshot.c
>> +++ b/block/qcow2-snapshot.c
>> @@ -562,12 +562,11 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const
>> char *snapshot_id)
>> * Now update the in-memory L1 table to be in sync with the on-disk
>> one. We
>> * need to do this even if updating refcounts failed.
>> */
>> - memset(s->l1_table, 0, s->l1_size*sizeof(uint64_t));
>> - for(i = 0;i < sn->l1_size; i++) {
>> + memset(s->l1_table, 0, s->l1_size * sizeof(uint64_t));
>> + for (i = 0; i < sn->l1_size; i++) {
>> s->l1_table[i] = be64_to_cpu(sn_l1_table[i]);
>> }
>>
>> -
>> if (ret < 0) {
>> goto fail;
>> }
>> diff --git a/block/qcow2.c b/block/qcow2.c
>> index 70ec890..58b53e1 100644
>> --- a/block/qcow2.c
>> +++ b/block/qcow2.c
>> @@ -2503,14 +2503,14 @@ static int qcow2_truncate(BlockDriverState *bs,
>> int64_t offset)
>>
>> bool v3_truncate = (s->qcow_version == 3);
>>
>> - /* cannot proceed if image has snapshots and qcow_version is not 3*/
>> + /* cannot proceed if image has snapshots and qcow_version is not 3 */
>> if (!v3_truncate && s->nb_snapshots) {
>> error_report("Can't resize an image which has snapshots and "
>> "qcow_version is not 3");
>> return -ENOTSUP;
>> }
>>
>> - /* shrinking is supported from version 3*/
>> + /* shrinking is supported from version 3 */
>> if (!v3_truncate && offset < bs->total_sectors * 512) {
>> error_report("qcow2 doesn't support shrinking images yet while"
>> " qcow_version is not 3");
>> --
>> 1.7.1
>>
>>
>>> On Jun 1, 2016, at 12:50 AM, Eric Blake <address@hidden
>>> <mailto:address@hidden>> wrote:
>>>
>>> On 05/27/2016 02:14 AM, zhangzhiming wrote:
>>>> Hi, i modified my code for qcow2 resize, and delete some code related to
>>>> qemu monitor.
>>>>
>>>> and thanks for the review.
>>>>
>>>> zhangzhiming
>>>> address@hidden <mailto:address@hidden> <mailto:address@hidden
>>>> <mailto:address@hidden>>
>>>
>>> Still missing a Signed-off-by designation, so it can't be applied as-is.
>>>
>>>>
>>>> ---
>>>> block.c | 19 +++++++++++++++++++
>>>> block/qcow2-cluster.c | 29 +++++++++++++++++++++++++++++
>>>> block/qcow2-snapshot.c | 34 ++++++++++++++++++++++++----------
>>>> block/qcow2.c | 29 ++++++++++++++++++++---------
>>>> block/qcow2.h | 1 +
>>>> include/block/snapshot.h | 1 +
>>>> 6 files changed, 94 insertions(+), 19 deletions(-)
>>>>
>>>> diff --git a/block.c b/block.c
>>>> index 18a497f..729f820 100644
>>>> --- a/block.c
>>>> +++ b/block.c
>>>> @@ -2631,6 +2631,25 @@ 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); /* void return */
>>>> + if (bs->blk) {
>>>> + blk_dev_resize_cb(bs->blk); /* void return too */
>>>
>>> The comments don't add anything here.
>>>
>>>> + }
>>>> + 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 31ecc10..e4c5c05 100644
>>>> --- a/block/qcow2-cluster.c
>>>> +++ b/block/qcow2-cluster.c
>>>> @@ -31,6 +31,35 @@
>>>> #include "block/qcow2.h"
>>>> #include "trace.h"
>>>>
>>>> +int shrink_l1_table(BlockDriverState *bs, int64_t new_l1_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);
>>>
>>> Indentation is off.
>>>
>>>> + if (ret < 0) {
>>>> + return ret;
>>>> + }
>>>> +
>>>> + s->l1_size = old_l1_size;
>>>> + ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset,
>>>> + s->l1_size, -1);
>>>
>>> and again.
>>>
>>>> + if (ret < 0) {
>>>> + return ret;
>>>> + }
>>>> + s->l1_size = new_l1_size;
>>>> +
>>>
>>>> +++ b/block/qcow2-snapshot.c
>>>
>>>> @@ -552,10 +562,12 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const
>>>> char *snapshot_id)
>>>> * Now update the in-memory L1 table to be in sync with the on-disk
>>>> one. We
>>>> * need to do this even if updating refcounts failed.
>>>> */
>>>> - for(i = 0;i < s->l1_size; i++) {
>>>> + memset(s->l1_table, 0, s->l1_size*sizeof(uint64_t));
>>>> + for(i = 0;i < sn->l1_size; i++) {
>>>
>>> As long as you are touching this, use the preferred spacing:
>>>
>>> for (i = 0; i < sn->l1_size; i++) {
>>>
>>>> s->l1_table[i] = be64_to_cpu(sn_l1_table[i]);
>>>> }
>>>>
>>>> +
>>>> if (ret < 0) {
>>>
>>> Why the added blank line?
>>>
>>>
>>>> +++ b/block/qcow2.c
>>>> @@ -2501,22 +2501,33 @@ static int qcow2_truncate(BlockDriverState *bs,
>>>> int64_t offset)
>>>> return -EINVAL;
>>>> }
>>>>
>>>> - /* cannot proceed if image has snapshots */
>>>> - if (s->nb_snapshots) {
>>>> - error_report("Can't resize an image which has snapshots");
>>>> + bool v3_truncate = (s->qcow_version == 3);
>>>> +
>>>> + /* cannot proceed if image has snapshots and qcow_version is not 3*/
>>>
>>> Space before */
>>>
>>>> + if (!v3_truncate && s->nb_snapshots) {
>>>> + error_report("Can't resize an image which has snapshots and "
>>>> + "qcow_version is not 3");
>>>> return -ENOTSUP;
>>>> }
>>>>
>>>> - /* shrinking is currently not supported */
>>>> - if (offset < bs->total_sectors * 512) {
>>>> - error_report("qcow2 doesn't support shrinking images yet");
>>>> + /* shrinking is supported from version 3*/
>>>
>>> and again
>>>
>>>> + if (!v3_truncate && offset < bs->total_sectors * 512) {
>>>> + error_report("qcow2 doesn't support shrinking images yet while"
>>>> + " qcow_version is not 3");
>>>> return -ENOTSUP;
>>>> }
>>>
>>>
>>> --
>>> Eric Blake eblake redhat com +1-919-301-3266
>>> Libvirt virtualization library http://libvirt.org <http://libvirt.org/>
>>>
>>
>