[PATCH v2 1/3] block: add BDRV_BLOCK_COMPRESSED flag for bdrv_block_status()

[Andrey Drobyshev via <qemu-devel@nongnu.org>]

Functions qcow2_get_host_offset(), get_cluster_offset(),
vmdk_co_block_status() explicitly report compressed cluster types when data
is compressed.  However, this information is never passed further.  Let's
make use of it by adding new BDRV_BLOCK_COMPRESSED flag for
bdrv_block_status(), so that caller may know that the data range is
compressed.  In particular, we're going to use this flag to tweak
"qemu-img map" output.

This new flag is only being utilized by qcow, qcow2 and vmdk formats, as only
those support compression.

Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
---
 block/qcow.c                 | 5 ++++-
 block/qcow2.c                | 3 +++
 block/vmdk.c                 | 2 ++
 include/block/block-common.h | 3 +++
 4 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/block/qcow.c b/block/qcow.c
index 577bd70324..d56d24ab6d 100644
--- a/block/qcow.c
+++ b/block/qcow.c
@@ -549,7 +549,10 @@ qcow_co_block_status(BlockDriverState *bs, bool want_zero,
     if (!cluster_offset) {
         return 0;
     }
-    if ((cluster_offset & QCOW_OFLAG_COMPRESSED) || s->crypto) {
+    if (cluster_offset & QCOW_OFLAG_COMPRESSED) {
+        return BDRV_BLOCK_DATA | BDRV_BLOCK_COMPRESSED;
+    }
+    if (s->crypto) {
         return BDRV_BLOCK_DATA;
     }
     *map = cluster_offset | index_in_cluster;
diff --git a/block/qcow2.c b/block/qcow2.c
index c51388e99d..77885fe27c 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -2162,6 +2162,9 @@ qcow2_co_block_status(BlockDriverState *bs, bool want_zero, int64_t offset,
     {
         status |= BDRV_BLOCK_RECURSE;
     }
+    if (type == QCOW2_SUBCLUSTER_COMPRESSED) {
+        status |= BDRV_BLOCK_COMPRESSED;
+    }
     return status;
 }
 
diff --git a/block/vmdk.c b/block/vmdk.c
index 70066c2b01..56b3d5151d 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -1770,6 +1770,8 @@ vmdk_co_block_status(BlockDriverState *bs, bool want_zero,
             if (extent->flat) {
                 ret |= BDRV_BLOCK_RECURSE;
             }
+        } else {
+            ret |= BDRV_BLOCK_COMPRESSED;
         }
         *file = extent->file->bs;
         break;
diff --git a/include/block/block-common.h b/include/block/block-common.h
index e15395f2cb..f7a4e7d4db 100644
--- a/include/block/block-common.h
+++ b/include/block/block-common.h
@@ -282,6 +282,8 @@ typedef enum {
  *                       layer rather than any backing, set by block layer
  * BDRV_BLOCK_EOF: the returned pnum covers through end of file for this
  *                 layer, set by block layer
+ * BDRV_BLOCK_COMPRESSED: the underlying data is compressed; only valid for
+ *                        the formats supporting compression: qcow, qcow2
  *
  * Internal flags:
  * BDRV_BLOCK_RAW: for use by passthrough drivers, such as raw, to request
@@ -317,6 +319,7 @@ typedef enum {
 #define BDRV_BLOCK_ALLOCATED    0x10
 #define BDRV_BLOCK_EOF          0x20
 #define BDRV_BLOCK_RECURSE      0x40
+#define BDRV_BLOCK_COMPRESSED   0x80
 
 typedef QTAILQ_HEAD(BlockReopenQueue, BlockReopenQueueEntry) BlockReopenQueue;
 
-- 
2.39.3