[Qemu-block] [PATCH 5/6] block: Add QMP support for streaming to an intermediate layer

[Alberto Garcia]

This patch makes the 'device' paramater of the 'block-stream' command
allow a node name as well as a device name.

In addition to that, operation blockers will be checked in all
intermediate nodes between the top and the base node.

Signed-off-by: Alberto Garcia <address@hidden>
---
 blockdev.c           | 20 ++++++++++----------
 qapi/block-core.json | 10 +++++++---
 2 files changed, 17 insertions(+), 13 deletions(-)

diff --git a/blockdev.c b/blockdev.c
index dc5d931..f24cf2d 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -2104,8 +2104,7 @@ void qmp_block_stream(const char *device,
                       bool has_on_error, BlockdevOnError on_error,
                       Error **errp)
 {
-    BlockBackend *blk;
-    BlockDriverState *bs;
+    BlockDriverState *bs, *i;
     BlockDriverState *base_bs = NULL;
     AioContext *aio_context;
     Error *local_err = NULL;
@@ -2115,20 +2114,14 @@ void qmp_block_stream(const char *device,
         on_error = BLOCKDEV_ON_ERROR_REPORT;
     }
 
-    blk = blk_by_name(device);
-    if (!blk) {
-        error_set(errp, QERR_DEVICE_NOT_FOUND, device);
+    bs = bdrv_lookup_bs(device, device, errp);
+    if (!bs) {
         return;
     }
-    bs = blk_bs(blk);
 
     aio_context = bdrv_get_aio_context(bs);
     aio_context_acquire(aio_context);
 
-    if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_STREAM, errp)) {
-        goto out;
-    }
-
     if (has_base) {
         base_bs = bdrv_find_backing_image(bs, base);
         if (base_bs == NULL) {
@@ -2139,6 +2132,13 @@ void qmp_block_stream(const char *device,
         base_name = base;
     }
 
+    /* Check for op blockers in the whole chain between bs and base */
+    for (i = bs; i != NULL && i != base_bs; i = i->backing_hd) {
+        if (bdrv_op_is_blocked(i, BLOCK_OP_TYPE_STREAM, errp)) {
+            goto out;
+        }
+    }
+
     /* if we are streaming the entire chain, the result will have no backing
      * file, and specifying one is therefore an error */
     if (base_bs == NULL && has_backing_file) {
diff --git a/qapi/block-core.json b/qapi/block-core.json
index 3639454..60b9664 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -1014,6 +1014,10 @@
 # with query-block-jobs.  The operation can be stopped before it has completed
 # using the block-job-cancel command.
 #
+# The node that receives the data is called the top image, can be located
+# in any part of the whole chain and can be specified using its device
+# or node name.
+#
 # If a base file is specified then sectors are not copied from that base file 
and
 # its backing chain.  When streaming completes the image file will have the 
base
 # file as its backing file.  This can be used to stream a subset of the backing
@@ -1022,12 +1026,12 @@
 # On successful completion the image file is updated to drop the backing file
 # and the BLOCK_JOB_COMPLETED event is emitted.
 #
-# @device: the device name
+# @device: the device or node name of the top image
 #
 # @base:   #optional the common backing file name
 #
-# @backing-file: #optional The backing file string to write into the active
-#                          layer. This filename is not validated.
+# @backing-file: #optional The backing file string to write into the top
+#                          image. This filename is not validated.
 #
 #                          If a pathname string is such that it cannot be
 #                          resolved by QEMU, that means that subsequent QMP or
-- 
2.1.4