On 25.02.2017 18:07, Vladimir Sementsov-Ogievskiy wrote: > Auto loading bitmaps are bitmaps in Qcow2, with the AUTO flag set. They > are loaded when the image is opened and become BdrvDirtyBitmaps for the > corresponding drive. > > Extra data in bitmaps is not supported for now. > > Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com> > --- > block/qcow2-bitmap.c | 367 > +++++++++++++++++++++++++++++++++++++++++++++++++++ > block/qcow2.c | 7 + > block/qcow2.h | 2 + > 3 files changed, 376 insertions(+) > > diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c > index b8e472b3e8..73a6e87038 100644 > --- a/block/qcow2-bitmap.c > +++ b/block/qcow2-bitmap.c
[...]
> +static int update_ext_header_and_dir_in_place(BlockDriverState *bs,
> + Qcow2BitmapList *bm_list)
> +{
> + BDRVQcow2State *s = bs->opaque;
> + int ret;
> +
> + if (!(s->autoclear_features & QCOW2_AUTOCLEAR_BITMAPS) ||
> + bm_list == NULL || QSIMPLEQ_EMPTY(bm_list) ||
> + bitmap_list_count(bm_list) != s->nb_bitmaps)
> + {
> + return -EINVAL;
> + }
> +
> + s->autoclear_features &= ~(uint64_t)QCOW2_AUTOCLEAR_BITMAPS;
> + ret = update_header_sync(bs);
> + if (ret < 0) {
> + /* Two variants are possible here:
> + * 1. Autoclear flag is dropped, all bitmaps will be lost.
> + * 2. Autoclear flag is not dropped, old state is left.
> + */
> + return ret;
> + }
> +
> + /* autoclear bit is not set, so we can safely update bitmap directory */
> +
> + ret = bitmap_list_store(bs, bm_list, &s->bitmap_directory_offset,
> + &s->bitmap_directory_size, true);
> + if (ret < 0) {
> + /* autoclear bit is cleared, so all leaked clusters would be removed
> on
> + * qemu-img check */
> + return ret;
> + }
> +
> + ret = update_header_sync(bs);
> + if (ret < 0) {
> + /* autoclear bit is cleared, so all leaked clusters would be removed
> on
> + * qemu-img check */
> + return ret;
> + }
> +
> + s->autoclear_features |= QCOW2_AUTOCLEAR_BITMAPS;
> + return update_header_sync(bs);
> + /* If final update_header_sync() fails, two variants are possible:
> + * 1. Autoclear flag is not set, all bitmaps will be lost.
> + * 2. Autoclear flag is set, header and directory are successfully
> updated.
> + */
Oh, nice. Thanks for the explanations, too. This way I'm very much fine
with update_header_sync() failing if bdrv_flush() fails.
> +}
> +
> +/* for g_slist_foreach for GSList of BdrvDirtyBitmap* elements */
> +static void release_dirty_bitmap_helper(gpointer bitmap,
> + gpointer bs)
> +{
> + bdrv_release_dirty_bitmap(bs, bitmap);
> +}
[...]
> diff --git a/block/qcow2.c b/block/qcow2.c
> index 6cd411f9c5..f4bb9d46de 100644
> --- a/block/qcow2.c
> +++ b/block/qcow2.c
> @@ -1237,6 +1237,13 @@ static int qcow2_open(BlockDriverState *bs, QDict
> *options, int flags,
> goto fail;
> }
>
> + qcow2_load_autoloading_dirty_bitmaps(bs, &local_err);
> + if (local_err != NULL) {
> + error_propagate(errp, local_err);
> + ret = -EINVAL;
> + goto fail;
> + }
> +
> /* Clear unknown autoclear feature bits */
> need_update_header |= s->autoclear_features & ~QCOW2_AUTOCLEAR_MASK;
>
I think it would be better to load the dirty bitmaps after clearing
unknown autoclear bits, because loading the bitmaps may result in
modifications of the image file.
Max
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