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Re: [Qemu-devel] [PATCH 14/22] qcow2: delete bitmaps on truncate
From: |
Max Reitz |
Subject: |
Re: [Qemu-devel] [PATCH 14/22] qcow2: delete bitmaps on truncate |
Date: |
Fri, 7 Oct 2016 21:58:31 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 |
On 30.09.2016 12:53, Vladimir Sementsov-Ogievskiy wrote:
> This will not touch loaded bitmaps, as they are alredy removed from the
> image.
Well, yes, and I don't think that's ideal. :-)
I think marking them in_use instead of deleting them would be better.
Also, I'm not so sure whether this patch is an improvement at all.
Wouldn't it be better to have a qemu-img tool (and/or QMP interface) for
bitmap management and then making the user delete all the bitmaps before
the image can be resized?
Max
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
> ---
> block/qcow2-bitmap.c | 38 ++++++++++++++++++++++++++++++++++++++
> block/qcow2.c | 9 ++++++---
> block/qcow2.h | 2 ++
> 3 files changed, 46 insertions(+), 3 deletions(-)
>
> diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c
> index 1c3abea..2642afe 100644
> --- a/block/qcow2-bitmap.c
> +++ b/block/qcow2-bitmap.c
> @@ -624,6 +624,44 @@ out:
> return ret;
> }
>
> +
> +int qcow2_delete_bitmaps(BlockDriverState *bs)
> +{
> + int ret;
> + BDRVQcow2State *s = bs->opaque;
> + uint8_t *dir;
> + uint64_t dir_size;
> + Qcow2BitmapDirEntry *e;
> +
> + if (s->nb_bitmaps == 0) {
> + /* No bitmaps - nothing to do */
> + return 0;
> + }
> +
> + dir_size = s->bitmap_directory_size;
> + dir = directory_read(bs, s->bitmap_directory_offset,
> + s->bitmap_directory_size, NULL);
> + if (dir == NULL) {
> + ret = -EINVAL;
> + goto out;
> + }
> +
> + ret = directory_update(bs, NULL, 0, 0);
> + if (ret < 0) {
> + goto out;
> + }
> +
> + /* to be consistent, free bitmap only after successfull directory update
> */
> + for_each_bitmap_dir_entry(e, dir, dir_size) {
> + free_bitmap_clusters(bs, e);
> + }
> +
> +out:
> + g_free(dir);
> +
> + return ret;
> +}
> +
> /* store_bitmap_data()
> * Store bitmap to image, filling bitamp table accordingly.
> */
> diff --git a/block/qcow2.c b/block/qcow2.c
> index 8238205..aa967ed 100644
> --- a/block/qcow2.c
> +++ b/block/qcow2.c
> @@ -2592,9 +2592,12 @@ static int qcow2_truncate(BlockDriverState *bs,
> int64_t offset)
>
> /* cannot proceed if image has bitmaps */
> if (s->nb_bitmaps) {
> - /* FIXME */
> - error_report("Can't resize an image which has bitmaps");
> - return -ENOTSUP;
> + /* FIXME: not loaded bitmaps will be lost */
> + ret = qcow2_delete_bitmaps(bs);
> + if (ret < 0) {
> + error_report("Can't remove bitmaps from qcow2 on truncate");
> + return ret;
> + }
> }
>
> /* shrinking is currently not supported */
> diff --git a/block/qcow2.h b/block/qcow2.h
> index dfcf4c6..af18efc 100644
> --- a/block/qcow2.h
> +++ b/block/qcow2.h
> @@ -606,6 +606,8 @@ int qcow2_read_snapshots(BlockDriverState *bs);
> /* qcow2-bitmap.c functions */
> int qcow2_read_bitmaps(BlockDriverState *bs, Error **errp);
>
> +int qcow2_delete_bitmaps(BlockDriverState *bs);
> +
> /* qcow2-cache.c functions */
> Qcow2Cache *qcow2_cache_create(BlockDriverState *bs, int num_tables);
> int qcow2_cache_destroy(BlockDriverState* bs, Qcow2Cache *c);
>
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