[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [RFC PATCH v2 15/26] qcow2: Add subcluster support to zero_in_l2_sli
From: |
Max Reitz |
Subject: |
Re: [RFC PATCH v2 15/26] qcow2: Add subcluster support to zero_in_l2_slice() |
Date: |
Mon, 4 Nov 2019 16:04:40 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.1 |
On 26.10.19 23:25, Alberto Garcia wrote:
> Setting the QCOW_OFLAG_ZERO bit of the L2 entry is forbidden if an
> image has subclusters. Instead, the individual 'all zeroes' bits must
> be used.
>
> Signed-off-by: Alberto Garcia <address@hidden>
> ---
> block/qcow2-cluster.c | 14 ++++++++++----
> 1 file changed, 10 insertions(+), 4 deletions(-)
>
> diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
> index e67559152f..3e4ba8d448 100644
> --- a/block/qcow2-cluster.c
> +++ b/block/qcow2-cluster.c
> @@ -1852,7 +1852,7 @@ static int zero_in_l2_slice(BlockDriverState *bs,
> uint64_t offset,
> assert(nb_clusters <= INT_MAX);
>
> for (i = 0; i < nb_clusters; i++) {
> - uint64_t old_offset;
> + uint64_t old_offset, l2_entry = 0;
> QCow2ClusterType cluster_type;
>
> old_offset = get_l2_entry(s, l2_slice, l2_index + i);
> @@ -1869,12 +1869,18 @@ static int zero_in_l2_slice(BlockDriverState *bs,
> uint64_t offset,
>
> qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice);
> if (cluster_type == QCOW2_CLUSTER_COMPRESSED || unmap) {
> - set_l2_entry(s, l2_slice, l2_index + i, QCOW_OFLAG_ZERO);
> qcow2_free_any_clusters(bs, old_offset, 1,
> QCOW2_DISCARD_REQUEST);
It feels wrong to me to free the cluster before updating the L2 entry.
Max
> } else {
> - uint64_t entry = get_l2_entry(s, l2_slice, l2_index + i);
> - set_l2_entry(s, l2_slice, l2_index + i, entry | QCOW_OFLAG_ZERO);
> + l2_entry = get_l2_entry(s, l2_slice, l2_index + i);
> }
> +
> + if (has_subclusters(s)) {
> + set_l2_bitmap(s, l2_slice, l2_index + i,
> QCOW_L2_BITMAP_ALL_ZEROES);
> + } else {
> + l2_entry |= QCOW_OFLAG_ZERO;
> + }
> +
> + set_l2_entry(s, l2_slice, l2_index + i, l2_entry);
> }
>
> qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
>
signature.asc
Description: OpenPGP digital signature
- Re: [RFC PATCH v2 15/26] qcow2: Add subcluster support to zero_in_l2_slice(),
Max Reitz <=