[v4] block: do not drain while holding the graph lock

[PATCH v4 27/48] block: call bdrv_set_backing_hd() while unlocked in bdrv_open_backing_file()

Posted by Fiona Ebner 5 months, 2 weeks ago

This is in preparation to mark bdrv_set_backing_hd() as
GRAPH_UNLOCKED.

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
---
 block.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/block.c b/block.c
index 1da10d55f0..ca3b67b233 100644
--- a/block.c
+++ b/block.c
@@ -3632,7 +3632,8 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options,
     Error *local_err = NULL;
 
     GLOBAL_STATE_CODE();
-    GRAPH_RDLOCK_GUARD_MAINLOOP();
+
+    bdrv_graph_rdlock_main_loop();
 
     if (bs->backing != NULL) {
         goto free_exit;
@@ -3711,9 +3712,12 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options,
                 backing_hd->filename);
     }
 
+
     /* Hook up the backing file link; drop our reference, bs owns the
      * backing_hd reference now */
+    bdrv_graph_rdunlock_main_loop();
     ret = bdrv_set_backing_hd(bs, backing_hd, errp);
+    bdrv_graph_rdlock_main_loop();
     bdrv_unref(backing_hd);
 
     if (ret < 0) {
@@ -3725,6 +3729,7 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options,
 free_exit:
     g_free(backing_filename);
     qobject_unref(tmp_parent_options);
+    bdrv_graph_rdunlock_main_loop();
     return ret;
 }
 
-- 
2.39.5

Re: [PATCH v4 27/48] block: call bdrv_set_backing_hd() while unlocked in bdrv_open_backing_file()

Posted by Kevin Wolf 4 months, 2 weeks ago

Am 30.05.2025 um 17:11 hat Fiona Ebner geschrieben:
> This is in preparation to mark bdrv_set_backing_hd() as
> GRAPH_UNLOCKED.
> 
> Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
> ---
>  block.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/block.c b/block.c
> index 1da10d55f0..ca3b67b233 100644
> --- a/block.c
> +++ b/block.c
> @@ -3632,7 +3632,8 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options,
>      Error *local_err = NULL;
>  
>      GLOBAL_STATE_CODE();
> -    GRAPH_RDLOCK_GUARD_MAINLOOP();
> +
> +    bdrv_graph_rdlock_main_loop();
>  
>      if (bs->backing != NULL) {
>          goto free_exit;
> @@ -3711,9 +3712,12 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options,
>                  backing_hd->filename);
>      }
>  
> +

Extra blank line.

>      /* Hook up the backing file link; drop our reference, bs owns the
>       * backing_hd reference now */
> +    bdrv_graph_rdunlock_main_loop();
>      ret = bdrv_set_backing_hd(bs, backing_hd, errp);
> +    bdrv_graph_rdlock_main_loop();
>      bdrv_unref(backing_hd);
>  
>      if (ret < 0) {

Kevin