[PATCH v14 12/13] block/stream: add s->target_bs

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

Add a direct link to target bs for convenience and to simplify
following commit which will insert COR filter above target bs.

This is a part of original commit written by Andrey.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 block/stream.c | 23 ++++++++++-------------
 1 file changed, 10 insertions(+), 13 deletions(-)

diff --git a/block/stream.c b/block/stream.c
index a2744d07fe..a7fd8945ad 100644
--- a/block/stream.c
+++ b/block/stream.c
@@ -34,6 +34,7 @@ typedef struct StreamBlockJob {
     BlockJob common;
     BlockDriverState *base_overlay; /* COW overlay (stream from this) */
     BlockDriverState *above_base;   /* Node directly above the base */
+    BlockDriverState *target_bs;
     BlockdevOnError on_error;
     char *backing_file_str;
     bool bs_read_only;
@@ -54,24 +55,21 @@ static void stream_abort(Job *job)
     StreamBlockJob *s = container_of(job, StreamBlockJob, common.job);
 
     if (s->chain_frozen) {
-        BlockJob *bjob = &s->common;
-        bdrv_unfreeze_backing_chain(blk_bs(bjob->blk), s->above_base);
+        bdrv_unfreeze_backing_chain(s->target_bs, s->above_base);
     }
 }
 
 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_filters(bs);
+    BlockDriverState *unfiltered_bs = bdrv_skip_filters(s->target_bs);
     BlockDriverState *base = bdrv_filter_or_cow_bs(s->above_base);
     BlockDriverState *base_unfiltered;
     BlockDriverState *backing_bs;
     Error *local_err = NULL;
     int ret = 0;
 
-    bdrv_unfreeze_backing_chain(bs, s->above_base);
+    bdrv_unfreeze_backing_chain(s->target_bs, s->above_base);
     s->chain_frozen = false;
 
     if (bdrv_cow_child(unfiltered_bs)) {
@@ -111,13 +109,12 @@ static void stream_clean(Job *job)
 {
     StreamBlockJob *s = container_of(job, StreamBlockJob, common.job);
     BlockJob *bjob = &s->common;
-    BlockDriverState *bs = blk_bs(bjob->blk);
 
     /* Reopen the image back in read-only mode if necessary */
     if (s->bs_read_only) {
         /* Give up write permissions before making it read-only */
         blk_set_perm(bjob->blk, 0, BLK_PERM_ALL, &error_abort);
-        bdrv_reopen_set_read_only(bs, true, NULL);
+        bdrv_reopen_set_read_only(s->target_bs, true, NULL);
     }
 
     g_free(s->backing_file_str);
@@ -127,8 +124,7 @@ 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_filters(bs);
+    BlockDriverState *unfiltered_bs = bdrv_skip_filters(s->target_bs);
     bool enable_cor = !bdrv_cow_child(s->base_overlay);
     int64_t len;
     int64_t offset = 0;
@@ -141,7 +137,7 @@ static int coroutine_fn stream_run(Job *job, Error **errp)
         return 0;
     }
 
-    len = bdrv_getlength(bs);
+    len = bdrv_getlength(s->target_bs);
     if (len < 0) {
         return len;
     }
@@ -153,7 +149,7 @@ static int coroutine_fn stream_run(Job *job, Error **errp)
      * account.
      */
     if (enable_cor) {
-        bdrv_enable_copy_on_read(bs);
+        bdrv_enable_copy_on_read(s->target_bs);
     }
 
     for ( ; offset < len; offset += n) {
@@ -215,7 +211,7 @@ static int coroutine_fn stream_run(Job *job, Error **errp)
     }
 
     if (enable_cor) {
-        bdrv_disable_copy_on_read(bs);
+        bdrv_disable_copy_on_read(s->target_bs);
     }
 
     /* Do not remove the backing file if an error was there but ignored. */
@@ -330,6 +326,7 @@ void stream_start(const char *job_id, BlockDriverState *bs,
     s->base_overlay = base_overlay;
     s->above_base = above_base;
     s->backing_file_str = g_strdup(backing_file_str);
+    s->target_bs = bs;
     s->bs_read_only = bs_read_only;
     s->chain_frozen = true;
 
-- 
2.21.3