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authorKevin Wolf <kwolf@redhat.com>2012-03-02 19:35:58 +0100
committerKevin Wolf <kwolf@redhat.com>2012-03-12 15:14:07 +0100
commit256900b16b0264af9e165bceabbf74dcece4ea38 (patch)
tree396c9278779d88bc4bb831b3b58780867a69d3ff /block
parentbf319ece56bc07608bfdf46b8ef5c61b52be83f6 (diff)
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qcow2: Add qcow2_alloc_clusters_at()
This function allows to allocate clusters at a given offset in the image file. This is useful if you want to allocate the second part of an area that must be contiguous. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Diffstat (limited to 'block')
-rw-r--r--block/qcow2-refcount.c28
-rw-r--r--block/qcow2.h2
2 files changed, 30 insertions, 0 deletions
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index 2db2ede..f39928a 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -582,6 +582,34 @@ int64_t qcow2_alloc_clusters(BlockDriverState *bs, int64_t size)
return offset;
}
+int qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t offset,
+ int nb_clusters)
+{
+ BDRVQcowState *s = bs->opaque;
+ uint64_t cluster_index;
+ int i, refcount, ret;
+
+ /* Check how many clusters there are free */
+ cluster_index = offset >> s->cluster_bits;
+ for(i = 0; i < nb_clusters; i++) {
+ refcount = get_refcount(bs, cluster_index++);
+
+ if (refcount < 0) {
+ return refcount;
+ } else if (refcount != 0) {
+ break;
+ }
+ }
+
+ /* And then allocate them */
+ ret = update_refcount(bs, offset, i << s->cluster_bits, 1);
+ if (ret < 0) {
+ return ret;
+ }
+
+ return i;
+}
+
/* only used to allocate compressed sectors. We try to allocate
contiguous sectors. size must be <= cluster_size */
int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size)
diff --git a/block/qcow2.h b/block/qcow2.h
index fc35838..5129e3e 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -193,6 +193,8 @@ int qcow2_refcount_init(BlockDriverState *bs);
void qcow2_refcount_close(BlockDriverState *bs);
int64_t qcow2_alloc_clusters(BlockDriverState *bs, int64_t size);
+int qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t offset,
+ int nb_clusters);
int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size);
void qcow2_free_clusters(BlockDriverState *bs,
int64_t offset, int64_t size);