[Qemu-devel] [PATCH RFC 7/7] nbd/replication: implement .bdrv_get_info() for nbd and replication driver

[zhanghailiang <zhang.zhanghailiang@huawei.com>]

Without this callback, there will be an error reports in the primary side:
"qemu-system-x86_64: Couldn't determine the cluster size of the target image,
which has no backing file: Operation not supported
Aborting, since this may create an unusable destination image"

For nbd driver, it doesn't have cluster size, so here we return
a fake value for it.

Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
---
 block/nbd.c         | 12 ++++++++++++
 block/replication.c |  6 ++++++
 2 files changed, 18 insertions(+)

diff --git a/block/nbd.c b/block/nbd.c
index 6bc06d6..96d7023 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -40,6 +40,8 @@
 
 #define EN_OPTSTR ":exportname="
 
+#define NBD_FAKE_CLUSTER_SIZE 512
+
 typedef struct BDRVNBDState {
     NbdClientSession client;
 
@@ -483,6 +485,13 @@ static void nbd_refresh_filename(BlockDriverState *bs, QDict *options)
     bs->full_open_options = opts;
 }
 
+static int nbd_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
+{
+    bdi->cluster_size  = NBD_FAKE_CLUSTER_SIZE;
+
+    return 0;
+}
+
 static BlockDriver bdrv_nbd = {
     .format_name                = "nbd",
     .protocol_name              = "nbd",
@@ -499,6 +508,7 @@ static BlockDriver bdrv_nbd = {
     .bdrv_detach_aio_context    = nbd_detach_aio_context,
     .bdrv_attach_aio_context    = nbd_attach_aio_context,
     .bdrv_refresh_filename      = nbd_refresh_filename,
+    .bdrv_get_info              = nbd_get_info,
 };
 
 static BlockDriver bdrv_nbd_tcp = {
@@ -517,6 +527,7 @@ static BlockDriver bdrv_nbd_tcp = {
     .bdrv_detach_aio_context    = nbd_detach_aio_context,
     .bdrv_attach_aio_context    = nbd_attach_aio_context,
     .bdrv_refresh_filename      = nbd_refresh_filename,
+    .bdrv_get_info              = nbd_get_info,
 };
 
 static BlockDriver bdrv_nbd_unix = {
@@ -535,6 +546,7 @@ static BlockDriver bdrv_nbd_unix = {
     .bdrv_detach_aio_context    = nbd_detach_aio_context,
     .bdrv_attach_aio_context    = nbd_attach_aio_context,
     .bdrv_refresh_filename      = nbd_refresh_filename,
+    .bdrv_get_info              = nbd_get_info,
 };
 
 static void bdrv_nbd_init(void)
diff --git a/block/replication.c b/block/replication.c
index e66b1ca..14c718e 100644
--- a/block/replication.c
+++ b/block/replication.c
@@ -707,6 +707,11 @@ static void replication_stop(ReplicationState *rs, bool failover, Error **errp)
     aio_context_release(aio_context);
 }
 
+static int replication_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
+{
+    return bdrv_get_info(bs->file->bs, bdi);
+}
+
 BlockDriver bdrv_replication = {
     .format_name                = "replication",
     .protocol_name              = "replication",
@@ -719,6 +724,7 @@ BlockDriver bdrv_replication = {
     .bdrv_co_readv              = replication_co_readv,
     .bdrv_co_writev             = replication_co_writev,
 
+    .bdrv_get_info              = replication_get_info,
     .is_filter                  = true,
     .bdrv_recurse_is_first_non_filter = replication_recurse_is_first_non_filter,
 
-- 
1.8.3.1