[Qemu-block,v1,1/1] qcow2 resize with snapshots

Commit Message

zhangzhiming May 19, 2016, 11:41 a.m. UTC

hi, and some extra code need to be changed.

zhangzhiming
[e-mail]
--



--

> On May 19, 2016, at 4:56 PM, zhangzhiming <[e-mail]> wrote:
> 
> hi, missed some code.
> 
> zhangzhiming
> [e-mail] <mailto:[e-mail]>
> 
> --
> 
> diff --git a/block.c b/block.c
> index 047698a..ff83134 100644
> --- a/block.c
> +++ b/block.c
> @@ -2641,7 +2641,7 @@ int bdrv_apply_snapshot(BlockDriverState *bs, const char *snapshot_id, uint64_t
>          return ret;
>      }
>  
> -    ret = refresh_total_sectors(bs, snapshot_size);
> +    ret = refresh_total_sectors(bs, snapshot_size >> BDRV_SECTOR_BITS);
>      bdrv_dirty_bitmap_truncate(bs);
>      if (bs->blk) {
>          blk_dev_resize_cb(bs->blk);
> diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c
> index 9bc987f..d872cf2 100644
> --- a/block/qcow2-snapshot.c
> +++ b/block/qcow2-snapshot.c
> @@ -528,6 +528,14 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const char *snapshot_id)
>          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;
> +    }
> +
>      /*
>       * Decrease refcount of clusters of current L1 table.
>       *
> 
> 
> --
> 
>> On May 19, 2016, at 3:46 PM, zhangzhiming <[e-mail] <mailto:[e-mail]>> wrote:
>> 
>> hi, i wrote some code for 'qcow2 resize' with snapshot with v3 image and 'qcow2 goto’ too, 
>> different size of snapshots are supported. 
>> and i have tested the function and it  seems work well.
>> there are some code copied from snapshot_delete_blkdev_internal, and qmp_block_resize, 
>> it feels not very good.
>> 
>> please review it for me. thanks.
>> 
>> zhangzhiming
>> [e-mail] <mailto:[e-mail]>
>> 
>> --
>> 
>> diff --git a/block.c b/block.c
>> index 18a497f..047698a 100644
>> --- a/block.c
>> +++ b/block.c
>> @@ -2632,6 +2632,24 @@ int bdrv_truncate(BlockDriverState *bs, int64_t offset)
>> }
>> 
>> /**
>> + *  goto a snapshot
>> + */
>> +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_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-snapshot.c b/block/qcow2-snapshot.c
>> index 5f4a17e..9bc987f 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
>> @@ -675,6 +668,7 @@ 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..6535f92 100644
>> --- a/block/qcow2.c
>> +++ b/block/qcow2.c
>> @@ -2501,15 +2501,17 @@ 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;
>>     }
>> 
>> diff --git a/block/sheepdog.c b/block/sheepdog.c
>> index 23fbace..bc12f7b 100644
>> --- a/block/sheepdog.c
>> +++ b/block/sheepdog.c
>> @@ -2693,6 +2693,7 @@ static int sd_snapshot_list(BlockDriverState *bs, QEMUSnapshotInfo **psn_tab)
>>             sn_tab[found].date_nsec = inode.snap_ctime & 0xffffffff;
>>             sn_tab[found].vm_state_size = inode.vm_state_size;
>>             sn_tab[found].vm_clock_nsec = inode.vm_clock_nsec;
>> +            sn_tab[found].disk_size = inode.vdi_size;
>> 
>>             snprintf(sn_tab[found].id_str, sizeof(sn_tab[found].id_str),
>>                      "%" PRIu32, inode.snap_id);
>> diff --git a/blockdev.c b/blockdev.c
>> index 1892b8e..36c66c1 100644
>> --- a/blockdev.c
>> +++ b/blockdev.c
>> @@ -2961,6 +2961,120 @@ out:
>>     aio_context_release(aio_context);
>> }
>> 
>> +SnapshotInfo *qmp_blockdev_snapshot_goto_internal_sync(const char *device,
>> +                             bool has_id,
>> +                             const char *id,
>> +                             bool has_name,
>> +                             const char *name,
>> +                             Error **errp)
>> +{
>> +    BlockDriverState *bs;
>> +    BlockBackend *blk;
>> +    AioContext *aio_context;
>> +    QEMUSnapshotInfo sn;
>> +    Error *local_err = NULL;
>> +    SnapshotInfo *info = NULL;
>> +    int ret;
>> +
>> +    blk = blk_by_name(device);
>> +    if (!blk) {
>> +        error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND,
>> +                "Device '%s' not found", device);
>> +        return NULL;
>> +    }
>> +    aio_context = blk_get_aio_context(blk);
>> +    aio_context_acquire(aio_context);
>> +
>> +    if(!has_id){
>> +        id = NULL;
>> +    }
>> +
>> +    if(!has_name){
>> +        name = NULL;
>> +    }
>> +
>> +    if(!id && !name){
>> +        error_setg(errp, "Name or id must be provided");
>> +        goto out_aio_context;
>> +    }
>> +
>> +    if(!blk_is_available(blk)){
>> +        error_setg(errp, "Device '%s' has no medium", device);
>> +        goto out_aio_context;
>> +    }
>> +
>> +    bs = blk_bs(blk);
>> +
>> +    if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_INTERNAL_SNAPSHOT_APPLY, errp)){
>> +        goto out_aio_context;
>> +    }
>> +
>> +    ret = bdrv_snapshot_find_by_id_and_name(bs, id, name, &sn, &local_err);
>> +    if(local_err){
>> +        error_propagate(errp, local_err);
>> +        goto out_aio_context;
>> +    }
>> +    if(!ret){
>> +        error_setg(errp,
>> +                   "Snapshot with id '%s' and name '%s' does not exist on "
>> +                   "device '%s'",
>> +                   STR_OR_NULL(id), STR_OR_NULL(name), device);
>> +        goto out_aio_context;
>> +    }
>> +    if(!sn.disk_size){
>> +        error_setg(errp,
>> +                   "Snapshot with id '%s' and name '%s' does not has a disk size "
>> +                   "device '%s'",
>> +                   STR_OR_NULL(id), STR_OR_NULL(name), device);
>> +        goto out_aio_context;
>> +    }
>> +
>> +    /* complete all in-flight operations before resizing the device */
>> +    bdrv_drain_all();
>> +
>> +    ret = bdrv_apply_snapshot(bs, sn.id_str, sn.disk_size);
>> +    switch (ret) {
>> +    case 0:
>> +        break;
>> +    case -ENOMEDIUM:
>> +        error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM, device);
>> +        break;
>> +    case -ENOTSUP:
>> +        error_setg(errp, QERR_UNSUPPORTED);
>> +        break;
>> +    case -EACCES:
>> +        error_setg(errp, "Device '%s' is read only", device);
>> +        break;
>> +    case -EBUSY:
>> +        error_setg(errp, QERR_DEVICE_IN_USE, device);
>> +        break;
>> +    default:
>> +        error_setg_errno(errp, -ret, "Could not resize");
>> +        break;
>> +    }
>> +
>> +    if(ret < 0){
>> +        goto out_aio_context;
>> +    }
>> +
>> +    aio_context_release(aio_context);
>> +
>> +    info = g_new0(SnapshotInfo, 1);
>> +    info->id = g_strdup(sn.id_str);
>> +    info->name = g_strdup(sn.name);
>> +    info->date_nsec = sn.date_nsec;
>> +    info->date_sec = sn.date_sec;
>> +    info->vm_state_size = sn.vm_state_size;
>> +    info->vm_clock_nsec = sn.vm_clock_nsec % 1000000000;
>> +    info->vm_clock_sec = sn.vm_clock_nsec / 1000000000;
>> +
>> +    return info;
>> +
>> +out_aio_context:
>> +    aio_context_release(aio_context);
>> +    return NULL;
>> +}
>> +
>> static void block_job_cb(void *opaque, int ret)
>> {
>>     /* Note that this function may be executed from another AioContext besides
>> diff --git a/hmp-commands.hx b/hmp-commands.hx
>> index 4f4f60a..5848a57 100644
>> --- a/hmp-commands.hx
>> +++ b/hmp-commands.hx
>> @@ -1159,6 +1159,24 @@ Delete an internal snapshot on device if it support
>> ETEXI
>> 
>>     {
>> +        .name       = "snapshot_goto_blkdev_internal",
>> +        .args_type  = "device:B,name:s,id:s?",
>> +        .params     = "device name [id]",
>> +        .help       = "apply an internal snapshot of device.\n\t\t\t"
>> +                      "If id is specified, qemu will try apply\n\t\t\t"
>> +                      "the snapshot matching both id and name.\n\t\t\t"
>> +                      "The format of the image used by device must\n\t\t\t"
>> +                      "support it, such as qcow2.\n\t\t\t",
>> +        .mhandler.cmd = hmp_snapshot_goto_blkdev_internal,
>> +    },
>> +
>> +STEXI
>> +@item snapshot_goto_blkdev_internal
>> +@findex snapshot_goto_blkdev_internal
>> +Apply an internal snapshot on device if it support
>> +ETEXI
>> +
>> +    {
>>         .name       = "drive_mirror",
>>         .args_type  = "reuse:-n,full:-f,device:B,target:s,format:s?",
>>         .params     = "[-n] [-f] device target [format]",
>> diff --git a/hmp.c b/hmp.c
>> index d510236..3f1d146 100644
>> --- a/hmp.c
>> +++ b/hmp.c
>> @@ -1057,6 +1057,8 @@ void hmp_block_resize(Monitor *mon, const QDict *qdict)
>>     hmp_handle_error(mon, &err);
>> }
>> 
>> +
>> +
>> void hmp_drive_mirror(Monitor *mon, const QDict *qdict)
>> {
>>     const char *device = qdict_get_str(qdict, "device");
>> @@ -1163,6 +1165,17 @@ void hmp_snapshot_delete_blkdev_internal(Monitor *mon, const QDict *qdict)
>>     hmp_handle_error(mon, &err);
>> }
>> 
>> +void hmp_snapshot_goto_blkdev_internal(Monitor *mon, const QDict *qdict)
>> +{
>> +    const char *device = qdict_get_str(qdict, "device");
>> +    const char *name = qdict_get_str(qdict, "name");
>> +    const char *id = qdict_get_try_str(qdict, "id");
>> +    Error *err = NULL;
>> +
>> +    qmp_blockdev_snapshot_goto_internal_sync(device, !!id, id, true, name, &err);
>> +    hmp_handle_error(mon, &err);
>> +}
>> +
>> void hmp_migrate_cancel(Monitor *mon, const QDict *qdict)
>> {
>>     qmp_migrate_cancel(NULL);
>> diff --git a/hmp.h b/hmp.h
>> index 093d65f..b1ad2f5 100644
>> --- a/hmp.h
>> +++ b/hmp.h
>> @@ -59,6 +59,7 @@ void hmp_block_resize(Monitor *mon, const QDict *qdict);
>> void hmp_snapshot_blkdev(Monitor *mon, const QDict *qdict);
>> void hmp_snapshot_blkdev_internal(Monitor *mon, const QDict *qdict);
>> void hmp_snapshot_delete_blkdev_internal(Monitor *mon, const QDict *qdict);
>> +void hmp_snapshot_goto_blkdev_internal(Monitor *mon, const QDict *qdict);
>> void hmp_drive_mirror(Monitor *mon, const QDict *qdict);
>> void hmp_drive_backup(Monitor *mon, const QDict *qdict);
>> void hmp_migrate_cancel(Monitor *mon, const QDict *qdict);
>> diff --git a/include/block/block.h b/include/block/block.h
>> index b210832..393ca6b 100644
>> --- a/include/block/block.h
>> +++ b/include/block/block.h
>> @@ -173,6 +173,7 @@ typedef enum BlockOpType {
>>     BLOCK_OP_TYPE_EXTERNAL_SNAPSHOT,
>>     BLOCK_OP_TYPE_INTERNAL_SNAPSHOT,
>>     BLOCK_OP_TYPE_INTERNAL_SNAPSHOT_DELETE,
>> +    BLOCK_OP_TYPE_INTERNAL_SNAPSHOT_APPLY,
>>     BLOCK_OP_TYPE_MIRROR_SOURCE,
>>     BLOCK_OP_TYPE_MIRROR_TARGET,
>>     BLOCK_OP_TYPE_RESIZE,
>> @@ -266,6 +267,7 @@ BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs,
>> int bdrv_get_backing_file_depth(BlockDriverState *bs);
>> void bdrv_refresh_filename(BlockDriverState *bs);
>> int bdrv_truncate(BlockDriverState *bs, int64_t offset);
>> +int bdrv_apply_snapshot(BlockDriverState *bs, const char *snapshot_id, uint64_t snapshot_size);
>> int64_t bdrv_nb_sectors(BlockDriverState *bs);
>> int64_t bdrv_getlength(BlockDriverState *bs);
>> int64_t bdrv_get_allocated_file_size(BlockDriverState *bs);
>> 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,
>> diff --git a/pixman b/pixman
>> index 87eea99..7c6066b 160000
>> --- a/pixman
>> +++ b/pixman
>> @@ -1 +1 @@
>> -Subproject commit 87eea99e443b389c978cf37efc52788bf03a0ee0
>> +Subproject commit 7c6066b700c7cdd4aeb8be426b14b3a5f0de4b6c
>> 
>> --
>> 
>> 
>

Patch

diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c
index d872cf2..fb888b0 100644
--- a/block/qcow2-snapshot.c
+++ b/block/qcow2-snapshot.c
@@ -498,7 +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;
@@ -523,7 +523,7 @@  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;
     }
@@ -536,6 +536,15 @@  int qcow2_snapshot_goto(BlockDriverState *bs, const char *snapshot_id)
         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.
      *
@@ -553,10 +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++) {
         s->l1_table[i] = be64_to_cpu(sn_l1_table[i]);
     }
 
+
     if (ret < 0) {
         goto fail;
     }
@@ -564,6 +575,7 @@  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.