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Re: [RFC PATCH v2 02/26] qcow2: Split cluster_needs_cow() out of count_c
From: |
Vladimir Sementsov-Ogievskiy |
Subject: |
Re: [RFC PATCH v2 02/26] qcow2: Split cluster_needs_cow() out of count_cow_clusters() |
Date: |
Mon, 28 Oct 2019 13:55:11 +0000 |
27.10.2019 0:25, Alberto Garcia wrote:
> We are going to need it in other places.
>
> Signed-off-by: Alberto Garcia <address@hidden>
Reviewed-by: Vladimir Sementsov-Ogievskiy <address@hidden>
> ---
> block/qcow2-cluster.c | 34 +++++++++++++++++++---------------
> 1 file changed, 19 insertions(+), 15 deletions(-)
>
> diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
> index 6c1dcdc781..aa1010a515 100644
> --- a/block/qcow2-cluster.c
> +++ b/block/qcow2-cluster.c
> @@ -1068,6 +1068,24 @@ static void calculate_l2_meta(BlockDriverState *bs,
> uint64_t host_offset,
> QLIST_INSERT_HEAD(&s->cluster_allocs, *m, next_in_flight);
> }
>
> +/* Returns true if writing to a cluster requires COW */
> +static bool cluster_needs_cow(BlockDriverState *bs, uint64_t l2_entry)
> +{
> + switch (qcow2_get_cluster_type(bs, l2_entry)) {
> + case QCOW2_CLUSTER_NORMAL:
> + if (l2_entry & QCOW_OFLAG_COPIED) {
> + return false;
> + }
> + case QCOW2_CLUSTER_UNALLOCATED:
> + case QCOW2_CLUSTER_COMPRESSED:
> + case QCOW2_CLUSTER_ZERO_PLAIN:
> + case QCOW2_CLUSTER_ZERO_ALLOC:
> + return true;
> + default:
> + abort();
> + }
> +}
Not sure how much is it better than just
return !(qcow2_get_cluster_type(bs, l2_entry) == QCOW2_CLUSTER_NORMAL &&
(l2_entry & QCOW_OFLAG_COPIED));
> +
> /*
> * Returns the number of contiguous clusters that can be used for an
> allocating
> * write, but require COW to be performed (this includes yet unallocated
> space,
> @@ -1080,25 +1098,11 @@ static int count_cow_clusters(BlockDriverState *bs,
> int nb_clusters,
>
> for (i = 0; i < nb_clusters; i++) {
> uint64_t l2_entry = be64_to_cpu(l2_slice[l2_index + i]);
> - QCow2ClusterType cluster_type = qcow2_get_cluster_type(bs, l2_entry);
> -
> - switch(cluster_type) {
> - case QCOW2_CLUSTER_NORMAL:
> - if (l2_entry & QCOW_OFLAG_COPIED) {
> - goto out;
> - }
> + if (!cluster_needs_cow(bs, l2_entry)) {
> break;
> - case QCOW2_CLUSTER_UNALLOCATED:
> - case QCOW2_CLUSTER_COMPRESSED:
> - case QCOW2_CLUSTER_ZERO_PLAIN:
> - case QCOW2_CLUSTER_ZERO_ALLOC:
> - break;
> - default:
> - abort();
> }
> }
>
> -out:
> assert(i <= nb_clusters);
> return i;
> }
>
--
Best regards,
Vladimir
- [RFC PATCH v2 12/26] qcow2: Handle QCOW2_CLUSTER_UNALLOCATED_SUBCLUSTER, (continued)
- [RFC PATCH v2 12/26] qcow2: Handle QCOW2_CLUSTER_UNALLOCATED_SUBCLUSTER, Alberto Garcia, 2019/10/26
- [RFC PATCH v2 23/26] qcow2: Restrict qcow2_co_pwrite_zeroes() to full clusters only, Alberto Garcia, 2019/10/26
- [RFC PATCH v2 09/26] qcow2: Add l2_entry_size(), Alberto Garcia, 2019/10/26
- [RFC PATCH v2 11/26] qcow2: Add qcow2_get_subcluster_type(), Alberto Garcia, 2019/10/26
- [RFC PATCH v2 15/26] qcow2: Add subcluster support to zero_in_l2_slice(), Alberto Garcia, 2019/10/26
- [RFC PATCH v2 17/26] qcow2: Add subcluster support to check_refcounts_l2(), Alberto Garcia, 2019/10/26
- [RFC PATCH v2 03/26] qcow2: Process QCOW2_CLUSTER_ZERO_ALLOC clusters in handle_copied(), Alberto Garcia, 2019/10/26
- [RFC PATCH v2 02/26] qcow2: Split cluster_needs_cow() out of count_cow_clusters(), Alberto Garcia, 2019/10/26
- Re: [RFC PATCH v2 02/26] qcow2: Split cluster_needs_cow() out of count_cow_clusters(),
Vladimir Sementsov-Ogievskiy <=
- [RFC PATCH v2 04/26] qcow2: Add get_l2_entry() and set_l2_entry(), Alberto Garcia, 2019/10/26
- [RFC PATCH v2 26/26] iotests: Add tests for qcow2 images with extended L2 entries, Alberto Garcia, 2019/10/26
- [RFC PATCH v2 24/26] qcow2: Add the 'extended_l2' option and the QCOW2_INCOMPAT_EXTL2 bit, Alberto Garcia, 2019/10/26