qemu-devel
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] [Qemu-block] [PATCH] qcow2 resize with snapshot


From: zhangzhiming
Subject: Re: [Qemu-devel] [Qemu-block] [PATCH] qcow2 resize with snapshot
Date: Wed, 1 Jun 2016 18:24:22 +0800

hi, here are all changes of my code. thanks for the review!  

zhangzhiming
address@hidden

Signed-off-by: zhangzhiming <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> 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/>
>> 
> 



reply via email to

[Prev in Thread] Current Thread [Next in Thread]