[Qemu-devel] [RFC 18/24] qcow2: add qcow2_map

[Devin Nakamura <devin122@gmail.com>]

Signed-off-by: Devin Nakamura <devin122@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) {
+        return -EINVAL;
+    }
+
+    if (contiguous_bytes % s->cluster_size) {
+        return -EINVAL;
+    }
+
+    nelms = s->l2_size / sizeof(uint64_t);
+
+    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;
+            }
+        }
+        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);
+            host_offset += s->cluster_size;
+            contiguous_bytes -= s->cluster_size;
+        }
+
+        qcow2_cache_put(bs, s->l2_table_cache, (void **) &l2_table);
+
+    }
+    return 0;
+}
diff --git a/block/qcow2.c b/block/qcow2.c
index 05ea40c..b75364d 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1445,6 +1445,7 @@ static BlockDriver bdrv_qcow2 = {
     .bdrv_check = qcow2_check,
 
     .bdrv_get_mapping = qcow2_get_mapping,
+    .bdrv_map         = qcow2_map,
 };
 
 static void bdrv_qcow2_init(void)
diff --git a/block/qcow2.h b/block/qcow2.h
index e9efb74..feea866 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -245,4 +245,7 @@ int qcow2_cache_get_empty(BlockDriverState *bs, Qcow2Cache *c, uint64_t offset,
     void **table);
 int qcow2_cache_put(BlockDriverState *bs, Qcow2Cache *c, void **table);
 
+int qcow2_map(BlockDriverState *bs, uint64_t guest_offset, uint64_t host_ofset,
+              uint64_t contiguous_bytes);
+
 #endif
-- 
1.7.6.rc1