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authorMax Reitz <mreitz@redhat.com>2015-02-06 09:39:16 -0500
committerKevin Wolf <kwolf@redhat.com>2015-02-06 17:24:22 +0100
commit8c44dfbc62a50a8bc4113f199b8662861f757591 (patch)
tree9377fcba318699096b9e3e1a7e8a97ff5bde98b9 /block/qcow2-refcount.c
parent8e8cb375e0964b4ed099cb8563029028db26a834 (diff)
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qcow2: Rewrite qcow2_alloc_bytes()
qcow2_alloc_bytes() is a function with insufficient error handling and an unnecessary goto. This patch rewrites it. Signed-off-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'block/qcow2-refcount.c')
-rw-r--r--block/qcow2-refcount.c78
1 files changed, 39 insertions, 39 deletions
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index 9afdb40..9b80ca7 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -759,54 +759,54 @@ int qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t offset,
int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size)
{
BDRVQcowState *s = bs->opaque;
- int64_t offset, cluster_offset;
- int free_in_cluster;
+ int64_t offset;
+ size_t free_in_cluster;
+ int ret;
BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_ALLOC_BYTES);
assert(size > 0 && size <= s->cluster_size);
- if (s->free_byte_offset == 0) {
- offset = qcow2_alloc_clusters(bs, s->cluster_size);
- if (offset < 0) {
- return offset;
+ assert(!s->free_byte_offset || offset_into_cluster(s, s->free_byte_offset));
+
+ offset = s->free_byte_offset;
+
+ if (offset) {
+ int refcount = qcow2_get_refcount(bs, offset >> s->cluster_bits);
+ if (refcount < 0) {
+ return refcount;
}
- s->free_byte_offset = offset;
- }
- redo:
- free_in_cluster = s->cluster_size -
- offset_into_cluster(s, s->free_byte_offset);
- if (size <= free_in_cluster) {
- /* enough space in current cluster */
- offset = s->free_byte_offset;
- s->free_byte_offset += size;
- free_in_cluster -= size;
- if (free_in_cluster == 0)
- s->free_byte_offset = 0;
- if (offset_into_cluster(s, offset) != 0)
- qcow2_update_cluster_refcount(bs, offset >> s->cluster_bits, 1,
- QCOW2_DISCARD_NEVER);
- } else {
- offset = qcow2_alloc_clusters(bs, s->cluster_size);
- if (offset < 0) {
- return offset;
+
+ if (refcount == 0xffff) {
+ offset = 0;
}
- cluster_offset = start_of_cluster(s, s->free_byte_offset);
- if ((cluster_offset + s->cluster_size) == offset) {
- /* we are lucky: contiguous data */
- offset = s->free_byte_offset;
- qcow2_update_cluster_refcount(bs, offset >> s->cluster_bits, 1,
- QCOW2_DISCARD_NEVER);
- s->free_byte_offset += size;
- } else {
- s->free_byte_offset = offset;
- goto redo;
+ }
+
+ free_in_cluster = s->cluster_size - offset_into_cluster(s, offset);
+ if (!offset || free_in_cluster < size) {
+ int64_t new_cluster = alloc_clusters_noref(bs, s->cluster_size);
+ if (new_cluster < 0) {
+ return new_cluster;
+ }
+
+ if (!offset || ROUND_UP(offset, s->cluster_size) != new_cluster) {
+ offset = new_cluster;
}
}
- /* The cluster refcount was incremented, either by qcow2_alloc_clusters()
- * or explicitly by qcow2_update_cluster_refcount(). Refcount blocks must
- * be flushed before the caller's L2 table updates.
- */
+ assert(offset);
+ ret = update_refcount(bs, offset, size, 1, QCOW2_DISCARD_NEVER);
+ if (ret < 0) {
+ return ret;
+ }
+
+ /* The cluster refcount was incremented; refcount blocks must be flushed
+ * before the caller's L2 table updates. */
qcow2_cache_set_dependency(bs, s->l2_table_cache, s->refcount_block_cache);
+
+ s->free_byte_offset = offset + size;
+ if (!offset_into_cluster(s, s->free_byte_offset)) {
+ s->free_byte_offset = 0;
+ }
+
return offset;
}