[Qemu-devel] [PATCH v2 0/3] block/stream: get rid of the base

[Qemu-devel] [PATCH v2 0/3] block/stream: get rid of the base

[Andrey Shinkevich]

This series introduces a bottom intermediate node that eliminates the
dependency on the base that may change while stream job is running.
It happens when stream/commit parallel jobs are running on the same
backing chain. The base node of the stream job may be a top node of
the parallel commit job and can change before the stream job is
completed. We avoid that dependency by introducing the bottom node.

v2:
The function bdrv_find_overlay() with the same functionality has been
used in the qmp_block_stream() to find a bottom node.
The algorithm in the bdrv_do_is_allocated_above() was simplified.
The commit messages were modified.

Discussed in the e-mail threads with the message IDs
<1553866154-257311-1-git-send-email-andrey.shinkevich@virtuozzo.com>
<1550762799-830661-1-git-send-email-andrey.shinkevich@virtuozzo.com>

Andrey Shinkevich (2):
  block: include base when checking image chain for block allocation
  block/stream: introduce a bottom node

Vladimir Sementsov-Ogievskiy (1):
  block/stream: refactor stream_run: drop goto

 block/io.c                | 32 ++++++++++++++++++----
 block/stream.c            | 67 ++++++++++++++++++++++-------------------------
 block/trace-events        |  2 +-
 blockdev.c                |  7 ++++-
 include/block/block.h     |  5 +++-
 include/block/block_int.h |  6 ++---
 tests/qemu-iotests/245    |  4 +--
 7 files changed, 74 insertions(+), 49 deletions(-)

-- 
1.8.3.1

[Qemu-devel] [PATCH v2 1/3] block: include base when checking image chain for block allocation

[Andrey Shinkevich]

This patch is used in the 'block/stream: introduce a bottom node'
that is following. Instead of the base node, the caller may pass
the node that has the base as its backing image to the new function
bdrv_is_allocated_above_inclusive() and get rid of the dependency
on the base that may change during commit/stream parallel jobs.
If the specified base is not found in the backing image chain, the
function fails.

Suggested-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
---
 block/io.c            | 32 +++++++++++++++++++++++++++-----
 include/block/block.h |  5 ++++-
 2 files changed, 31 insertions(+), 6 deletions(-)

diff --git a/block/io.c b/block/io.c
index dfc153b..7edeeb2 100644
--- a/block/io.c
+++ b/block/io.c
@@ -2317,7 +2317,8 @@ int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t offset,
  * Given an image chain: ... -> [BASE] -> [INTER1] -> [INTER2] -> [TOP]
  *
  * Return true if (a prefix of) the given range is allocated in any image
- * between BASE and TOP (inclusive).  BASE can be NULL to check if the given
+ * between BASE and TOP (TOP included). To check the BASE image, set the
+ * 'base_included' to 'true'. The BASE can be NULL to check if the given
  * offset is allocated in any image of the chain.  Return false otherwise,
  * or negative errno on failure.
  *
@@ -2329,16 +2330,18 @@ int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t offset,
  * but 'pnum' will only be 0 when end of file is reached.
  *
  */
-int bdrv_is_allocated_above(BlockDriverState *top,
-                            BlockDriverState *base,
-                            int64_t offset, int64_t bytes, int64_t *pnum)
+static int bdrv_do_is_allocated_above(BlockDriverState *top,
+                                      BlockDriverState *base,
+                                      bool base_included, int64_t offset,
+                                      int64_t bytes, int64_t *pnum)
 {
     BlockDriverState *intermediate;
     int ret;
     int64_t n = bytes;
+    assert(base || !base_included);
 
     intermediate = top;
-    while (intermediate && intermediate != base) {
+    while (base_included || intermediate != base) {
         int64_t pnum_inter;
         int64_t size_inter;
 
@@ -2360,6 +2363,10 @@ int bdrv_is_allocated_above(BlockDriverState *top,
             n = pnum_inter;
         }
 
+        if (intermediate == base) {
+            break;
+        }
+
         intermediate = backing_bs(intermediate);
     }
 
@@ -2367,6 +2374,21 @@ int bdrv_is_allocated_above(BlockDriverState *top,
     return 0;
 }
 
+int bdrv_is_allocated_above(BlockDriverState *top,
+                            BlockDriverState *base,
+                            int64_t offset, int64_t bytes, int64_t *pnum)
+{
+    return bdrv_do_is_allocated_above(top, base, false, offset, bytes, pnum);
+}
+
+int bdrv_is_allocated_above_inclusive(BlockDriverState *top,
+                                      BlockDriverState *base,
+                                      int64_t offset, int64_t bytes,
+                                      int64_t *pnum)
+{
+    return bdrv_do_is_allocated_above(top, base, true, offset, bytes, pnum);
+}
+
 typedef struct BdrvVmstateCo {
     BlockDriverState    *bs;
     QEMUIOVector        *qiov;
diff --git a/include/block/block.h b/include/block/block.h
index c7a2619..a7846d9 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -448,7 +448,10 @@ int bdrv_is_allocated(BlockDriverState *bs, int64_t offset, int64_t bytes,
                       int64_t *pnum);
 int bdrv_is_allocated_above(BlockDriverState *top, BlockDriverState *base,
                             int64_t offset, int64_t bytes, int64_t *pnum);
-
+int bdrv_is_allocated_above_inclusive(BlockDriverState *top,
+                                      BlockDriverState *base,
+                                      int64_t offset, int64_t bytes,
+                                      int64_t *pnum);
 bool bdrv_is_read_only(BlockDriverState *bs);
 int bdrv_can_set_read_only(BlockDriverState *bs, bool read_only,
                            bool ignore_allow_rdw, Error **errp);
-- 
1.8.3.1

[Qemu-devel] [PATCH v2 2/3] block/stream: refactor stream_run: drop goto

[Andrey Shinkevich]

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
---
 block/stream.c | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/block/stream.c b/block/stream.c
index 6253c86..c065e99 100644
--- a/block/stream.c
+++ b/block/stream.c
@@ -122,13 +122,12 @@ static int coroutine_fn stream_run(Job *job, Error **errp)
     void *buf;
 
     if (!bs->backing) {
-        goto out;
+        return 0;
     }
 
     len = bdrv_getlength(bs);
     if (len < 0) {
-        ret = len;
-        goto out;
+        return len;
     }
     job_progress_set_remaining(&s->common.job, len);
 
@@ -205,14 +204,10 @@ static int coroutine_fn stream_run(Job *job, Error **errp)
         bdrv_disable_copy_on_read(bs);
     }
 
-    /* Do not remove the backing file if an error was there but ignored.  */
-    ret = error;
-
     qemu_vfree(buf);
 
-out:
-    /* Modify backing chain and close BDSes in main loop */
-    return ret;
+    /* Do not remove the backing file if an error was there but ignored. */
+    return error;
 }
 
 static const BlockJobDriver stream_job_driver = {
-- 
1.8.3.1

[Qemu-devel] [PATCH v2 3/3] block/stream: introduce a bottom node

[Andrey Shinkevich]

The bottom node is the intermediate block device that has the base as its
backing image. It is used instead of the base node while a block stream
job is running to avoid dependency on the base that may change due to the
parallel jobs. The change may take place due to a filter node as well that
is inserted between the base and the intermediate bottom node. It occurs
when the base node is the top one for another commit or stream job.
After the introduction of the bottom node, don't freeze its backing child,
that's the base, anymore.

Suggested-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
---
 block/stream.c            | 54 +++++++++++++++++++++++------------------------
 block/trace-events        |  2 +-
 blockdev.c                |  7 +++++-
 include/block/block_int.h |  6 +++---
 tests/qemu-iotests/245    |  4 ++--
 5 files changed, 39 insertions(+), 34 deletions(-)

diff --git a/block/stream.c b/block/stream.c
index c065e99..913f04e 100644
--- a/block/stream.c
+++ b/block/stream.c
@@ -31,7 +31,7 @@ enum {
 
 typedef struct StreamBlockJob {
     BlockJob common;
-    BlockDriverState *base;
+    BlockDriverState *bottom;
     BlockdevOnError on_error;
     char *backing_file_str;
     bool bs_read_only;
@@ -56,7 +56,7 @@ static void stream_abort(Job *job)
 
     if (s->chain_frozen) {
         BlockJob *bjob = &s->common;
-        bdrv_unfreeze_backing_chain(blk_bs(bjob->blk), s->base);
+        bdrv_unfreeze_backing_chain(blk_bs(bjob->blk), s->bottom);
     }
 }
 
@@ -65,11 +65,11 @@ 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 *base = s->base;
+    BlockDriverState *base = backing_bs(s->bottom);
     Error *local_err = NULL;
     int ret = 0;
 
-    bdrv_unfreeze_backing_chain(bs, base);
+    bdrv_unfreeze_backing_chain(bs, s->bottom);
     s->chain_frozen = false;
 
     if (bs->backing) {
@@ -112,7 +112,7 @@ 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 *base = s->base;
+    bool enable_cor = !backing_bs(s->bottom);
     int64_t len;
     int64_t offset = 0;
     uint64_t delay_ns = 0;
@@ -121,7 +121,8 @@ static int coroutine_fn stream_run(Job *job, Error **errp)
     int64_t n = 0; /* bytes */
     void *buf;
 
-    if (!bs->backing) {
+    if (bs == s->bottom) {
+        /* Nothing to stream */
         return 0;
     }
 
@@ -138,7 +139,7 @@ static int coroutine_fn stream_run(Job *job, Error **errp)
      * backing chain since the copy-on-read operation does not take base into
      * account.
      */
-    if (!base) {
+    if (enable_cor) {
         bdrv_enable_copy_on_read(bs);
     }
 
@@ -161,9 +162,8 @@ static int coroutine_fn stream_run(Job *job, Error **errp)
         } 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_inclusive(backing_bs(bs), s->bottom,
+                                                    offset, n, &n);
             /* Finish early if end of backing file has been reached */
             if (ret == 0 && n == 0) {
                 n = len - offset;
@@ -200,7 +200,7 @@ static int coroutine_fn stream_run(Job *job, Error **errp)
         }
     }
 
-    if (!base) {
+    if (enable_cor) {
         bdrv_disable_copy_on_read(bs);
     }
 
@@ -225,13 +225,14 @@ static const BlockJobDriver stream_job_driver = {
 };
 
 void stream_start(const char *job_id, BlockDriverState *bs,
-                  BlockDriverState *base, const char *backing_file_str,
+                  BlockDriverState *bottom, const char *backing_file_str,
                   int creation_flags, int64_t speed,
                   BlockdevOnError on_error, Error **errp)
 {
     StreamBlockJob *s;
     BlockDriverState *iter;
     bool bs_read_only;
+    int basic_flags = BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED;
 
     /* Make sure that the image is opened in read-write mode */
     bs_read_only = bdrv_is_read_only(bs);
@@ -245,37 +246,36 @@ void stream_start(const char *job_id, BlockDriverState *bs,
      * already have our own plans. Also don't allow resize as the image size is
      * queried only at the job start and then cached. */
     s = block_job_create(job_id, &stream_job_driver, NULL, bs,
-                         BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED |
-                         BLK_PERM_GRAPH_MOD,
-                         BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED |
-                         BLK_PERM_WRITE,
+                         basic_flags | BLK_PERM_GRAPH_MOD,
+                         basic_flags | BLK_PERM_WRITE,
                          speed, creation_flags, NULL, NULL, errp);
     if (!s) {
         goto fail;
     }
 
-    /* Block all intermediate nodes between bs and base, because they will
-     * 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)) {
-        block_job_add_bdrv(&s->common, "intermediate node", iter, 0,
-                           BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED,
-                           &error_abort);
+    /*
+     * Block all intermediate nodes between bs and bottom (inclusive), because
+     * they will disappear from the chain after this operation. The streaming
+     * job reads every block only once, assuming that it doesn't change, so
+     * forbid writes and resizes.
+     */
+    for (iter = bs; iter != bottom; iter = backing_bs(iter)) {
+        block_job_add_bdrv(&s->common, "intermediate node", backing_bs(iter),
+                           0, basic_flags, &error_abort);
     }
 
-    if (bdrv_freeze_backing_chain(bs, base, errp) < 0) {
+    if (bdrv_freeze_backing_chain(bs, bottom, errp) < 0) {
         job_early_fail(&s->common.job);
         goto fail;
     }
 
-    s->base = base;
+    s->bottom = bottom;
     s->backing_file_str = g_strdup(backing_file_str);
     s->bs_read_only = bs_read_only;
     s->chain_frozen = true;
 
     s->on_error = on_error;
-    trace_stream_start(bs, base, s);
+    trace_stream_start(bs, bottom, s);
     job_start(&s->common.job);
     return;
 
diff --git a/block/trace-events b/block/trace-events
index e6bb5a8..36e7b79 100644
--- a/block/trace-events
+++ b/block/trace-events
@@ -20,7 +20,7 @@ bdrv_co_copy_range_to(void *src, uint64_t src_offset, void *dst, uint64_t dst_of
 
 # stream.c
 stream_one_iteration(void *s, int64_t offset, uint64_t bytes, int is_allocated) "s %p offset %" PRId64 " bytes %" PRIu64 " is_allocated %d"
-stream_start(void *bs, void *base, void *s) "bs %p base %p s %p"
+stream_start(void *bs, void *bottom, void *s) "bs %p bottom %p s %p"
 
 # commit.c
 commit_one_iteration(void *s, int64_t offset, uint64_t bytes, int is_allocated) "s %p offset %" PRId64 " bytes %" PRIu64 " is_allocated %d"
diff --git a/blockdev.c b/blockdev.c
index 4775a07..ce0cad4 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3164,6 +3164,7 @@ void qmp_block_stream(bool has_job_id, const char *job_id, const char *device,
 {
     BlockDriverState *bs, *iter;
     BlockDriverState *base_bs = NULL;
+    BlockDriverState *bottom_node = NULL;
     AioContext *aio_context;
     Error *local_err = NULL;
     const char *base_name = NULL;
@@ -3237,7 +3238,11 @@ void qmp_block_stream(bool has_job_id, const char *job_id, const char *device,
         job_flags |= JOB_MANUAL_DISMISS;
     }
 
-    stream_start(has_job_id ? job_id : NULL, bs, base_bs, base_name,
+    /* Find the bottom node that has the base as its backing image */
+    bottom_node = bdrv_find_overlay(bs, base_bs);
+    assert(bottom_node);
+
+    stream_start(has_job_id ? job_id : NULL, bs, bottom_node, base_name,
                  job_flags, has_speed ? speed : 0, on_error, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 01e855a..8ab1144 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -1019,8 +1019,8 @@ int is_windows_drive(const char *filename);
  * @job_id: The id of the newly-created job, or %NULL to use the
  * device name of @bs.
  * @bs: Block device to operate on.
- * @base: Block device that will become the new base, or %NULL to
- * flatten the whole backing file chain onto @bs.
+ * @bottom_node: The intermediate block device right above the new base.
+ * If base is %NULL, the whole backing file chain is flattened onto @bs.
  * @backing_file_str: The file name that will be written to @bs as the
  * the new backing file if the job completes. Ignored if @base is %NULL.
  * @creation_flags: Flags that control the behavior of the Job lifetime.
@@ -1037,7 +1037,7 @@ int is_windows_drive(const char *filename);
  * BlockDriverState.
  */
 void stream_start(const char *job_id, BlockDriverState *bs,
-                  BlockDriverState *base, const char *backing_file_str,
+                  BlockDriverState *bottom_node, const char *backing_file_str,
                   int creation_flags, int64_t speed,
                   BlockdevOnError on_error, Error **errp);
 
diff --git a/tests/qemu-iotests/245 b/tests/qemu-iotests/245
index 7891a21..d11e73c 100644
--- a/tests/qemu-iotests/245
+++ b/tests/qemu-iotests/245
@@ -859,9 +859,9 @@ class TestBlockdevReopen(iotests.QMPTestCase):
                              device = 'hd0', base_node = 'hd2', speed = 512 * 1024)
         self.assert_qmp(result, 'return', {})
 
-        # We can't remove hd2 while the stream job is ongoing
+        # We can remove hd2 while the stream job is ongoing
         opts['backing']['backing'] = None
-        self.reopen(opts, {}, "Cannot change 'backing' link from 'hd1' to 'hd2'")
+        self.reopen(opts, {})
 
         # We can't remove hd1 while the stream job is ongoing
         opts['backing'] = None
-- 
1.8.3.1

Re: [Qemu-devel] [PATCH v2 1/3] block: include base when checking image chain for block allocation

[Vladimir Sementsov-Ogievskiy]

01.04.2019 15:06, Andrey Shinkevich wrote:
> This patch is used in the 'block/stream: introduce a bottom node'
> that is following. Instead of the base node, the caller may pass
> the node that has the base as its backing image to the new function
> bdrv_is_allocated_above_inclusive() and get rid of the dependency
> on the base that may change during commit/stream parallel jobs.
> If the specified base is not found in the backing image chain, the
> function fails.

More honest: s/fail/now crashes/

And I think it's correct. But it would be good to check all callers.. Do we
freeze backing chain in all cases before calling this function?

> 
> Suggested-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
> ---
>   block/io.c            | 32 +++++++++++++++++++++++++++-----
>   include/block/block.h |  5 ++++-
>   2 files changed, 31 insertions(+), 6 deletions(-)
> 
> diff --git a/block/io.c b/block/io.c
> index dfc153b..7edeeb2 100644
> --- a/block/io.c
> +++ b/block/io.c
> @@ -2317,7 +2317,8 @@ int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t offset,
>    * Given an image chain: ... -> [BASE] -> [INTER1] -> [INTER2] -> [TOP]
>    *
>    * Return true if (a prefix of) the given range is allocated in any image
> - * between BASE and TOP (inclusive).  BASE can be NULL to check if the given
> + * between BASE and TOP (TOP included). To check the BASE image, set the
> + * 'base_included' to 'true'. The BASE can be NULL to check if the given
>    * offset is allocated in any image of the chain.  Return false otherwise,
>    * or negative errno on failure.
>    *
> @@ -2329,16 +2330,18 @@ int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t offset,
>    * but 'pnum' will only be 0 when end of file is reached.
>    *
>    */
> -int bdrv_is_allocated_above(BlockDriverState *top,
> -                            BlockDriverState *base,
> -                            int64_t offset, int64_t bytes, int64_t *pnum)
> +static int bdrv_do_is_allocated_above(BlockDriverState *top,
> +                                      BlockDriverState *base,
> +                                      bool base_included, int64_t offset,
> +                                      int64_t bytes, int64_t *pnum)
>   {
>       BlockDriverState *intermediate;
>       int ret;
>       int64_t n = bytes;

empty line after variable definitions

> +    assert(base || !base_included);
>   
>       intermediate = top;
> -    while (intermediate && intermediate != base) {
> +    while (base_included || intermediate != base) {
>           int64_t pnum_inter;
>           int64_t size_inter;
>   
> @@ -2360,6 +2363,10 @@ int bdrv_is_allocated_above(BlockDriverState *top,
>               n = pnum_inter;
>           }
>   
> +        if (intermediate == base) {
> +            break;
> +        }
> +
>           intermediate = backing_bs(intermediate);
>       }
>   
> @@ -2367,6 +2374,21 @@ int bdrv_is_allocated_above(BlockDriverState *top,
>       return 0;
>   }
>   
> +int bdrv_is_allocated_above(BlockDriverState *top,
> +                            BlockDriverState *base,
> +                            int64_t offset, int64_t bytes, int64_t *pnum)
> +{
> +    return bdrv_do_is_allocated_above(top, base, false, offset, bytes, pnum);
> +}
> +
> +int bdrv_is_allocated_above_inclusive(BlockDriverState *top,
> +                                      BlockDriverState *base,
> +                                      int64_t offset, int64_t bytes,
> +                                      int64_t *pnum)
> +{
> +    return bdrv_do_is_allocated_above(top, base, true, offset, bytes, pnum);
> +}
> +
>   typedef struct BdrvVmstateCo {
>       BlockDriverState    *bs;
>       QEMUIOVector        *qiov;
> diff --git a/include/block/block.h b/include/block/block.h
> index c7a2619..a7846d9 100644
> --- a/include/block/block.h
> +++ b/include/block/block.h
> @@ -448,7 +448,10 @@ int bdrv_is_allocated(BlockDriverState *bs, int64_t offset, int64_t bytes,
>                         int64_t *pnum);
>   int bdrv_is_allocated_above(BlockDriverState *top, BlockDriverState *base,
>                               int64_t offset, int64_t bytes, int64_t *pnum);
> -
> +int bdrv_is_allocated_above_inclusive(BlockDriverState *top,
> +                                      BlockDriverState *base,
> +                                      int64_t offset, int64_t bytes,
> +                                      int64_t *pnum);

dropped empty line better stay here.

>   bool bdrv_is_read_only(BlockDriverState *bs);
>   int bdrv_can_set_read_only(BlockDriverState *bs, bool read_only,
>                              bool ignore_allow_rdw, Error **errp);
> 


Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

-- 
Best regards,
Vladimir

Re: [Qemu-devel] [PATCH v2 3/3] block/stream: introduce a bottom node

[Vladimir Sementsov-Ogievskiy]

01.04.2019 15:06, Andrey Shinkevich wrote:
> The bottom node is the intermediate block device that has the base as its
> backing image. It is used instead of the base node while a block stream
> job is running to avoid dependency on the base that may change due to the
> parallel jobs. The change may take place due to a filter node as well that
> is inserted between the base and the intermediate bottom node. It occurs
> when the base node is the top one for another commit or stream job.
> After the introduction of the bottom node, don't freeze its backing child,
> that's the base, anymore.
> 
> Suggested-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
> ---
>   block/stream.c            | 54 +++++++++++++++++++++++------------------------
>   block/trace-events        |  2 +-
>   blockdev.c                |  7 +++++-
>   include/block/block_int.h |  6 +++---
>   tests/qemu-iotests/245    |  4 ++--
>   5 files changed, 39 insertions(+), 34 deletions(-)
> 

[..]

> diff --git a/blockdev.c b/blockdev.c
> index 4775a07..ce0cad4 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -3164,6 +3164,7 @@ void qmp_block_stream(bool has_job_id, const char *job_id, const char *device,
>   {
>       BlockDriverState *bs, *iter;
>       BlockDriverState *base_bs = NULL;
> +    BlockDriverState *bottom_node = NULL;
>       AioContext *aio_context;
>       Error *local_err = NULL;
>       const char *base_name = NULL;
> @@ -3237,7 +3238,11 @@ void qmp_block_stream(bool has_job_id, const char *job_id, const char *device,
>           job_flags |= JOB_MANUAL_DISMISS;
>       }
>   
> -    stream_start(has_job_id ? job_id : NULL, bs, base_bs, base_name,
> +    /* Find the bottom node that has the base as its backing image */
> +    bottom_node = bdrv_find_overlay(bs, base_bs);
> +    assert(bottom_node);

assert seems unnecessary now and even bottom_node variable. I think you can just call
bdrv_find_overly inside stream_start() parameter list.

with or without this change:
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>




-- 
Best regards,
Vladimir

Re: [Qemu-devel] [PATCH v2 2/3] block/stream: refactor stream_run: drop goto

[Alberto Garcia]

On Mon 01 Apr 2019 02:06:04 PM CEST, Andrey Shinkevich wrote:
> From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
> ---

You can also say in the log message that the goto is not necessary since
the common exit code was removed in commit eb23654dbe43b549ea2a9ebff9d8e

Reviewed-by: Alberto Garcia <berto@igalia.com>

Berto

Re: [Qemu-devel] [PATCH v2 2/3] block/stream: refactor stream_run: drop goto

[Andrey Shinkevich]

On 02/04/2019 15:43, Alberto Garcia wrote:
> On Mon 01 Apr 2019 02:06:04 PM CEST, Andrey Shinkevich wrote:
>> From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>>
>> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>> Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
>> ---
> 
> You can also say in the log message that the goto is not necessary since
> the common exit code was removed in commit eb23654dbe43b549ea2a9ebff9d8e
> 
> Reviewed-by: Alberto Garcia <berto@igalia.com>
> 
> Berto
> 

Alberto,
Thank you for the commit reference.
-- 
With the best regards,
Andrey Shinkevich