[Qemu-devel] [PATCH v5 28/42] stream: Deal with filters

[Max Reitz <mreitz@redhat.com>]

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 qapi/block-core.json |  4 ++++
 block/stream.c       | 23 +++++++++++++++--------
 blockdev.c           |  2 +-
 3 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/qapi/block-core.json b/qapi/block-core.json
index df52a90736..a3c5298cf5 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -2518,6 +2518,10 @@
 # On successful completion the image file is updated to drop the backing file
 # and the BLOCK_JOB_COMPLETED event is emitted.
 #
+# In case @device is a filter node, block-stream modifies the first non-filter
+# overlay node below it to point to base's backing node (or NULL if @base was
+# not specified) instead of modifying @device itself.
+#
 # @job-id: identifier for the newly-created block job. If
 #          omitted, the device name will be used. (Since 2.7)
 #
diff --git a/block/stream.c b/block/stream.c
index 1a906fd860..9271e1821a 100644
--- a/block/stream.c
+++ b/block/stream.c
@@ -63,6 +63,7 @@ static int stream_prepare(Job *job)
     StreamBlockJob *s = container_of(job, StreamBlockJob, common.job);
     BlockJob *bjob = &s->common;
     BlockDriverState *bs = blk_bs(bjob->blk);
+    BlockDriverState *unfiltered_bs = bdrv_skip_rw_filters(bs);
     BlockDriverState *base = s->base;
     Error *local_err = NULL;
     int ret = 0;
@@ -70,7 +71,7 @@ static int stream_prepare(Job *job)
     bdrv_unfreeze_backing_chain(bs, base);
     s->chain_frozen = false;
 
-    if (bs->backing) {
+    if (bdrv_filtered_cow_child(unfiltered_bs)) {
         const char *base_id = NULL, *base_fmt = NULL;
         if (base) {
             base_id = s->backing_file_str;
@@ -78,8 +79,8 @@ static int stream_prepare(Job *job)
                 base_fmt = base->drv->format_name;
             }
         }
-        ret = bdrv_change_backing_file(bs, base_id, base_fmt);
-        bdrv_set_backing_hd(bs, base, &local_err);
+        ret = bdrv_change_backing_file(unfiltered_bs, base_id, base_fmt);
+        bdrv_set_backing_hd(unfiltered_bs, base, &local_err);
         if (local_err) {
             error_report_err(local_err);
             return -EPERM;
@@ -110,7 +111,9 @@ static int coroutine_fn stream_run(Job *job, Error **errp)
     StreamBlockJob *s = container_of(job, StreamBlockJob, common.job);
     BlockBackend *blk = s->common.blk;
     BlockDriverState *bs = blk_bs(blk);
+    BlockDriverState *unfiltered_bs = bdrv_skip_rw_filters(bs);
     BlockDriverState *base = s->base;
+    BlockDriverState *filtered_base;
     int64_t len;
     int64_t offset = 0;
     uint64_t delay_ns = 0;
@@ -119,10 +122,12 @@ static int coroutine_fn stream_run(Job *job, Error **errp)
     int64_t n = 0; /* bytes */
     void *buf;
 
-    if (!bs->backing) {
+    if (!bdrv_filtered_cow_child(unfiltered_bs)) {
         goto out;
     }
 
+    filtered_base = bdrv_filtered_cow_bs(bdrv_find_overlay(bs, base));
+
     len = bdrv_getlength(bs);
     if (len < 0) {
         ret = len;
@@ -154,14 +159,14 @@ static int coroutine_fn stream_run(Job *job, Error **errp)
 
         copy = false;
 
-        ret = bdrv_is_allocated(bs, offset, STREAM_BUFFER_SIZE, &n);
+        ret = bdrv_is_allocated(unfiltered_bs, offset, STREAM_BUFFER_SIZE, &n);
         if (ret == 1) {
             /* Allocated in the top, no need to copy.  */
         } else if (ret >= 0) {
             /* Copy if allocated in the intermediate images.  Limit to the
              * known-unallocated area [offset, offset+n*BDRV_SECTOR_SIZE).  */
-            ret = bdrv_is_allocated_above(backing_bs(bs), base,
-                                          offset, n, &n);
+            ret = bdrv_is_allocated_above(bdrv_filtered_cow_bs(unfiltered_bs),
+                                          filtered_base, offset, n, &n);
 
             /* Finish early if end of backing file has been reached */
             if (ret == 0 && n == 0) {
@@ -266,7 +271,9 @@ void stream_start(const char *job_id, BlockDriverState *bs,
      * disappear from the chain after this operation. The streaming job reads
      * every block only once, assuming that it doesn't change, so block writes
      * and resizes. */
-    for (iter = backing_bs(bs); iter && iter != base; iter = backing_bs(iter)) {
+    for (iter = bdrv_filtered_bs(bs); iter && iter != base;
+         iter = bdrv_filtered_bs(iter))
+    {
         block_job_add_bdrv(&s->common, "intermediate node", iter, 0,
                            BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED,
                            &error_abort);
diff --git a/blockdev.c b/blockdev.c
index 5036d064d4..a464cabf9e 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3235,7 +3235,7 @@ void qmp_block_stream(bool has_job_id, const char *job_id, const char *device,
     }
 
     /* Check for op blockers in the whole chain between bs and base */
-    for (iter = bs; iter && iter != base_bs; iter = backing_bs(iter)) {
+    for (iter = bs; iter && iter != base_bs; iter = bdrv_filtered_bs(iter)) {
         if (bdrv_op_is_blocked(iter, BLOCK_OP_TYPE_STREAM, errp)) {
             goto out;
         }
-- 
2.21.0