[v4,08/11] block: distinguish between bdrv_create running in coroutine and not

Commit Message

Emanuele Giuseppe Esposito Nov. 16, 2022, 12:22 p.m. UTC

Call two different functions depending on whether bdrv_create
is in coroutine or not, following the same pattern as
generated_co_wrapper functions.

This allows to also call the coroutine function directly,
without using CreateCo or relying in bdrv_create().

Signed-off-by: Emanuele Giuseppe Esposito <[e-mail]>
---
 block.c | 76 ++++++++++++++++++++++++++++-----------------------------
 1 file changed, 38 insertions(+), 38 deletions(-)

Comments

Kevin Wolf Nov. 22, 2022, 8:45 a.m. UTC | #1

Am 16.11.2022 um 13:22 hat Emanuele Giuseppe Esposito geschrieben:
> Call two different functions depending on whether bdrv_create
> is in coroutine or not, following the same pattern as
> generated_co_wrapper functions.
> 
> This allows to also call the coroutine function directly,
> without using CreateCo or relying in bdrv_create().
> 
> Signed-off-by: Emanuele Giuseppe Esposito <[e-mail]>
> ---
>  block.c | 76 ++++++++++++++++++++++++++++-----------------------------
>  1 file changed, 38 insertions(+), 38 deletions(-)
> 
> diff --git a/block.c b/block.c
> index 577639c7e0..c610a32e77 100644
> --- a/block.c
> +++ b/block.c
> @@ -528,66 +528,66 @@ typedef struct CreateCo {
>      Error *err;
>  } CreateCo;
>  
> -static void coroutine_fn bdrv_create_co_entry(void *opaque)
> +static int coroutine_fn bdrv_co_create(BlockDriver *drv, const char *filename,
> +                                       QemuOpts *opts, Error **errp)
>  {
> -    Error *local_err = NULL;
>      int ret;
> +    char *filename_copy;
> +    GLOBAL_STATE_CODE();
> +    assert(*errp == NULL);

Your use of *errp in this function will crash if NULL is passed. You
need ERRP_GUARD() first before you can do this.

> +    assert(drv);
> +
> +    if (!drv->bdrv_co_create_opts) {
> +        error_setg(errp, "Driver '%s' does not support image creation",
> +                   drv->format_name);
> +        return -ENOTSUP;
> +    }
>  
> +    filename_copy = g_strdup(filename);

It's only preserved from the pre-patch state, but I don't think this is
necessary? We know that the string will stay around until the function
returns, and the parameter of drv->bdrv_co_create_opts is const char*,
so it must not be modified either.

Maybe worth a cleanup patch on top to just use filename directly?

> +    ret = drv->bdrv_co_create_opts(drv, filename_copy, opts, errp);
> +
> +    if (ret < 0 && !*errp) {
> +        error_setg_errno(errp, -ret, "Could not create image");
> +    }
> +
> +    g_free(filename_copy);
> +    return ret;
> +}

Kevin

Patch

diff --git a/block.c b/block.c
index 577639c7e0..c610a32e77 100644
--- a/block.c
+++ b/block.c
@@ -528,66 +528,66 @@  typedef struct CreateCo {
     Error *err;
 } CreateCo;
 
-static void coroutine_fn bdrv_create_co_entry(void *opaque)
+static int coroutine_fn bdrv_co_create(BlockDriver *drv, const char *filename,
+                                       QemuOpts *opts, Error **errp)
 {
-    Error *local_err = NULL;
     int ret;
+    char *filename_copy;
+    GLOBAL_STATE_CODE();
+    assert(*errp == NULL);
+    assert(drv);
+
+    if (!drv->bdrv_co_create_opts) {
+        error_setg(errp, "Driver '%s' does not support image creation",
+                   drv->format_name);
+        return -ENOTSUP;
+    }
 
+    filename_copy = g_strdup(filename);
+    ret = drv->bdrv_co_create_opts(drv, filename_copy, opts, errp);
+
+    if (ret < 0 && !*errp) {
+        error_setg_errno(errp, -ret, "Could not create image");
+    }
+
+    g_free(filename_copy);
+    return ret;
+}
+
+static void coroutine_fn bdrv_create_co_entry(void *opaque)
+{
     CreateCo *cco = opaque;
-    assert(cco->drv);
     GLOBAL_STATE_CODE();
 
-    ret = cco->drv->bdrv_co_create_opts(cco->drv,
-                                        cco->filename, cco->opts, &local_err);
-    error_propagate(&cco->err, local_err);
-    cco->ret = ret;
+    cco->ret = bdrv_co_create(cco->drv, cco->filename, cco->opts, &cco->err);
 }
 
 int bdrv_create(BlockDriver *drv, const char* filename,
                 QemuOpts *opts, Error **errp)
 {
-    int ret;
-
     GLOBAL_STATE_CODE();
 
-    Coroutine *co;
-    CreateCo cco = {
-        .drv = drv,
-        .filename = g_strdup(filename),
-        .opts = opts,
-        .ret = NOT_DONE,
-        .err = NULL,
-    };
-
-    if (!drv->bdrv_co_create_opts) {
-        error_setg(errp, "Driver '%s' does not support image creation", drv->format_name);
-        ret = -ENOTSUP;
-        goto out;
-    }
-
     if (qemu_in_coroutine()) {
         /* Fast-path if already in coroutine context */
-        bdrv_create_co_entry(&cco);
+        return bdrv_co_create(drv, filename, opts, errp);
     } else {
+        Coroutine *co;
+        CreateCo cco = {
+            .drv = drv,
+            .filename = filename,
+            .opts = opts,
+            .ret = NOT_DONE,
+            .err = NULL,
+        };
+
         co = qemu_coroutine_create(bdrv_create_co_entry, &cco);
         qemu_coroutine_enter(co);
         while (cco.ret == NOT_DONE) {
             aio_poll(qemu_get_aio_context(), true);
         }
+        error_propagate(errp, cco.err);
+        return cco.ret;
     }
-
-    ret = cco.ret;
-    if (ret < 0) {
-        if (cco.err) {
-            error_propagate(errp, cco.err);
-        } else {
-            error_setg_errno(errp, -ret, "Could not create image");
-        }
-    }
-
-out:
-    g_free(cco.filename);
-    return ret;
 }
 
 /**