Introduce two new helper functions handle_alloc() and
vmdk_alloc_cluster_offset(). handle_alloc() helps to allocate multiple
clusters at once starting from a given offset on disk and performs COW
if necessary for first and last allocated clusters.
vmdk_alloc_cluster_offset() helps to return the offset of the first of
the many newly allocated clusters. Also, provide proper documentation
for both.
Signed-off-by: Ashijeet Acharya <ashijeetacha...@gmail.com>
---
block/vmdk.c | 206 +++++++++++++++++++++++++++++++++++++++++++++++++++++------
1 file changed, 187 insertions(+), 19 deletions(-)
diff --git a/block/vmdk.c b/block/vmdk.c
index a42322e..5a95929 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -136,6 +136,7 @@ typedef struct VmdkMetaData {
unsigned int l2_offset;
int valid;
uint32_t *l2_cache_entry;
+ uint32_t nb_clusters;
} VmdkMetaData;
typedef struct VmdkGrainMarker {
@@ -1036,6 +1037,34 @@ static void vmdk_refresh_limits(BlockDriverState *bs,
Error **errp)
}
}
+static int vmdk_L2update(VmdkExtent *extent, VmdkMetaData *m_data,
+ uint32_t offset)
+{
+ offset = cpu_to_le32(offset);
+ /* update L2 table */
+ if (bdrv_pwrite_sync(extent->file,
+ ((int64_t)m_data->l2_offset * 512)
+ + (m_data->l2_index * sizeof(offset)),
+ &offset, sizeof(offset)) < 0) {
+ return VMDK_ERROR;
+ }
+ /* update backup L2 table */
+ if (extent->l1_backup_table_offset != 0) {
+ m_data->l2_offset = extent->l1_backup_table[m_data->l1_index];
+ if (bdrv_pwrite_sync(extent->file,
+ ((int64_t)m_data->l2_offset * 512)
+ + (m_data->l2_index * sizeof(offset)),
+ &offset, sizeof(offset)) < 0) {
+ return VMDK_ERROR;
+ }
+ }
+ if (m_data->l2_cache_entry) {
+ *m_data->l2_cache_entry = offset;
+ }
+
+ return VMDK_OK;
+}
+
/*
* vmdk_L2load
*
@@ -1222,29 +1251,168 @@ exit:
return ret;
}
-static int vmdk_L2update(VmdkExtent *extent, VmdkMetaData *m_data,
- uint32_t offset)
+/*
+ * handle_alloc
+ *
+ * Allocates new clusters for an area that either is yet unallocated or needs a
+ * copy on write. If *cluster_offset is non_zero, clusters are only allocated
if
+ * the new allocation can match the specified host offset.
+ *
+ * Returns:
+ * VMDK_OK: if new clusters were allocated, *bytes may be decreased if
+ * the new allocation doesn't cover all of the requested area.
+ * *cluster_offset is updated to contain the offset of the
+ * first newly allocated cluster.
+ *
+ * VMDK_UNALLOC: if no clusters could be allocated. *cluster_offset is left
+ * unchanged.
+ *
+ * VMDK_ERROR: in error cases
+ */
+static int handle_alloc(BlockDriverState *bs, VmdkExtent *extent,
+ uint64_t offset, uint64_t *cluster_offset,
+ int64_t *bytes, VmdkMetaData *m_data,
+ bool allocate, uint32_t *total_alloc_clusters)
{
- offset = cpu_to_le32(offset);
- /* update L2 table */
- if (bdrv_pwrite_sync(extent->file,
- ((int64_t)m_data->l2_offset * 512)
- + (m_data->l2_index * sizeof(offset)),
- &offset, sizeof(offset)) < 0) {
- return VMDK_ERROR;
+ int l1_index, l2_offset, l2_index;
+ uint32_t *l2_table;
+ uint32_t cluster_sector;
+ uint32_t nb_clusters;
+ bool zeroed = false;
+ uint64_t skip_start_bytes, skip_end_bytes;
+ int ret;
+
+ ret = get_cluster_table(extent, offset, &l1_index, &l2_offset,
+ &l2_index, &l2_table);
+ if (ret < 0) {
+ return ret;
}
- /* update backup L2 table */
- if (extent->l1_backup_table_offset != 0) {
- m_data->l2_offset = extent->l1_backup_table[m_data->l1_index];
- if (bdrv_pwrite_sync(extent->file,
- ((int64_t)m_data->l2_offset * 512)
- + (m_data->l2_index * sizeof(offset)),
- &offset, sizeof(offset)) < 0) {
- return VMDK_ERROR;
+
+ cluster_sector = le32_to_cpu(l2_table[l2_index]);
+
+ skip_start_bytes = vmdk_find_offset_in_cluster(extent, offset);
+ /* Calculate the number of clusters to look for. Here it will return one
+ * cluster less than the actual value calculated as we may need to perfrom
+ * COW for the last one. */
+ nb_clusters = size_to_clusters(extent, skip_start_bytes + *bytes);
+
+ nb_clusters = MIN(nb_clusters, extent->l2_size - l2_index);
+ assert(nb_clusters <= INT_MAX);
+
+ /* update bytes according to final nb_clusters value */
+ if (nb_clusters != 0) {
+ *bytes = ((nb_clusters * extent->cluster_sectors) << 9)
+ - skip_start_bytes;
+ } else {
+ nb_clusters = 1;
+ }
+ *total_alloc_clusters += nb_clusters;
+ skip_end_bytes = skip_start_bytes + MIN(*bytes,
+ extent->cluster_sectors * BDRV_SECTOR_SIZE
+ - skip_start_bytes);
+
+ if (extent->has_zero_grain && cluster_sector == VMDK_GTE_ZEROED) {
+ zeroed = true;
+ }
+
+ if (!cluster_sector || zeroed) {
+ if (!allocate) {
+ return zeroed ? VMDK_ZEROED : VMDK_UNALLOC;
+ }
+
+ cluster_sector = extent->next_cluster_sector;
+ extent->next_cluster_sector += extent->cluster_sectors
+ * nb_clusters;
+
+ ret = vmdk_perform_cow(bs, extent, cluster_sector * BDRV_SECTOR_SIZE,
+ offset, skip_start_bytes,
+ skip_end_bytes);
+ if (ret < 0) {
+ return ret;
+ }
+ if (m_data) {
+ m_data->valid = 1;
+ m_data->l1_index = l1_index;
+ m_data->l2_index = l2_index;
+ m_data->l2_offset = l2_offset;
+ m_data->l2_cache_entry = &l2_table[l2_index];
+ m_data->nb_clusters = nb_clusters;
}
}
- if (m_data->l2_cache_entry) {
- *m_data->l2_cache_entry = offset;
+ *cluster_offset = cluster_sector << BDRV_SECTOR_BITS;
+ return VMDK_OK;
+}
+
+/*
+ * vmdk_alloc_cluster_offset
+ *
+ * For a given offset on the virtual disk, find the cluster offset in vmdk
+ * file. If the offset is not found, allocate a new cluster.
+ *
+ * If the cluster is newly allocated, m_data->nb_clusters is set to the number
+ * of contiguous clusters that have been allocated. In this case, the other
+ * fields of m_data are valid and contain information about the first allocated
+ * cluster.
+ *
+ * Returns:
+ *
+ * VMDK_OK: on success and @cluster_offset was set
+ *
+ * VMDK_UNALLOC: if no clusters were allocated and @cluster_offset is
+ * set to zero
+ *
+ * VMDK_ERROR: in error cases
+ */
+static int vmdk_alloc_cluster_offset(BlockDriverState *bs,
+ VmdkExtent *extent,
+ VmdkMetaData *m_data, uint64_t offset,
+ bool allocate, uint64_t *cluster_offset,
+ int64_t bytes,
+ uint32_t *total_alloc_clusters)
+{
+ uint64_t start, remaining;
+ uint64_t new_cluster_offset;
+ int64_t n_bytes;
+ int ret;
+
+ if (extent->flat) {
+ *cluster_offset = extent->flat_start_offset;
+ return VMDK_OK;
+ }
+
+ start = offset;
+ remaining = bytes;
+ new_cluster_offset = 0;
+ *cluster_offset = 0;
+ n_bytes = 0;
+ if (m_data) {
+ m_data->valid = 0;
+ }
+
+ /* due to L2 table margins all bytes may not get allocated at once */
+ while (true) {
+
+ if (!*cluster_offset) {
+ *cluster_offset = new_cluster_offset;
+ }
+
+ start += n_bytes;
+ remaining -= n_bytes;
+ new_cluster_offset += n_bytes;
+
+ if (remaining == 0) {
+ break;
+ }
+
+ n_bytes = remaining;
+
+ ret = handle_alloc(bs, extent, start, &new_cluster_offset, &n_bytes,
+ m_data, allocate, total_alloc_clusters);
+
+ if (ret < 0) {
+ return ret;
+
+ }
}
return VMDK_OK;
--
2.6.2
