Am 29.07.2011 06:49, schrieb Devin Nakamura:
> Signed-off-by: Devin Nakamura <devin...@gmail.com>
> ---
> block/qcow2-cluster.c | 49
> +++++++++++++++++++++++++++++++++++++++++++++++++
> block/qcow2.c | 1 +
> block/qcow2.h | 3 +++
> 3 files changed, 53 insertions(+), 0 deletions(-)
>
> diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
> index ca56918..848f2ee 100644
> --- a/block/qcow2-cluster.c
> +++ b/block/qcow2-cluster.c
> @@ -977,3 +977,52 @@ int qcow2_discard_clusters(BlockDriverState *bs,
> uint64_t offset,
>
> return 0;
> }
> +
> +int qcow2_map(BlockDriverState *bs, uint64_t guest_offset,
> + uint64_t host_offset, uint64_t contiguous_bytes)
> +{
> + BDRVQcowState *s = bs->opaque;
> + unsigned int nelms;
> +
> +
> + if ((s->cluster_size - 1) & guest_offset) {
Usually you would have guest_offset first.
> + return -EINVAL;
> + }
> +
> + if (contiguous_bytes % s->cluster_size) {
> + return -EINVAL;
> + }
Any reason why the two checks are different? I don't really care if they
use & or %, but they should use the same thing.
host_offset isn't checked at all?
> +
> + nelms = s->l2_size / sizeof(uint64_t);
s->l2_size is already in elements, not in bytes.
> +
> + while (contiguous_bytes > 0) {
> + unsigned int l1_index, l2_index;
> + uint64_t *l2_table;
> + int ret;
> + l1_index = guest_offset >> (s->l2_bits + s->cluster_bits);
> + l2_index = (guest_offset >> s->cluster_bits) & (s->l2_size - 1);
> +
> + if (!s->l1_table[l1_index]) {
> + ret = l2_allocate(bs, l1_index, &l2_table);
> + if (ret) {
> + return ret;
> + }
> + } else {
> + ret = l2_load(bs, s->l1_table[l1_index] & ~QCOW_OFLAG_COPIED,
> &l2_table);
> + if (ret) {
> + return ret;
> + }
> + }
Can't you use get_cluster_table() for this part?
> + qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
> +
> + for (; l2_index < nelms && contiguous_bytes > 0; l2_index++) {
> + l2_table[l2_index] = cpu_to_be64(host_offset |
> QCOW_OFLAG_COPIED);
You should increase the refcount for host_offset and set
QCOW_OFLAG_COPIED only if it becomes 1. Or maybe we should just fail
bdrv_map if the old refcount is != 0.
> + host_offset += s->cluster_size;
> + contiguous_bytes -= s->cluster_size;
> + }
> +
> + qcow2_cache_put(bs, s->l2_table_cache, (void **) &l2_table);
> +
> + }
> + return 0;
> +}
Kevin
