block: Introduce bdrv_co_change_backing_file()

bdrv_change_backing_file() is called both inside and outside coroutine
context. This makes it difficult for it to take the graph lock
internally. It also means that driver implementations need to be able to
run outside of coroutines, too. Switch it to the usual model with a
coroutine based implementation and a co_wrapper instead. The new
function is marked GRAPH_RDLOCK.

As the co_wrapper now runs the function in the AioContext of the node
(as it should always have done), this is not GLOBAL_STATE_CODE() any
more.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20231027155333.420094-20-kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 32 insertions, 32 deletions

diff --git a/block/qed.c b/block/qed.c
index 686ad711f7..996aa384fe 100644
--- a/block/qed.c
+++ b/block/qed.c
@@ -1498,9 +1498,9 @@ bdrv_qed_co_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
     return 0;
 }
 
-static int bdrv_qed_change_backing_file(BlockDriverState *bs,
-                                        const char *backing_file,
-                                        const char *backing_fmt)
+static int coroutine_fn GRAPH_RDLOCK
+bdrv_qed_co_change_backing_file(BlockDriverState *bs, const char *backing_file,
+                                const char *backing_fmt)
 {
     BDRVQEDState *s = bs->opaque;
     QEDHeader new_header, le_header;
@@ -1562,7 +1562,7 @@ static int bdrv_qed_change_backing_file(BlockDriverState *bs,
     }
 
     /* Write new header */
-    ret = bdrv_pwrite_sync(bs->file, 0, buffer_len, buffer, 0);
+    ret = bdrv_co_pwrite_sync(bs->file, 0, buffer_len, buffer, 0);
     g_free(buffer);
     if (ret == 0) {
         memcpy(&s->header, &new_header, sizeof(new_header));
@@ -1636,34 +1636,34 @@ static QemuOptsList qed_create_opts = {
 };
 
 static BlockDriver bdrv_qed = {
-    .format_name              = "qed",
-    .instance_size            = sizeof(BDRVQEDState),
-    .create_opts              = &qed_create_opts,
-    .is_format                = true,
-    .supports_backing         = true,
-
-    .bdrv_probe               = bdrv_qed_probe,
-    .bdrv_open                = bdrv_qed_open,
-    .bdrv_close               = bdrv_qed_close,
-    .bdrv_reopen_prepare      = bdrv_qed_reopen_prepare,
-    .bdrv_child_perm          = bdrv_default_perms,
-    .bdrv_co_create           = bdrv_qed_co_create,
-    .bdrv_co_create_opts      = bdrv_qed_co_create_opts,
-    .bdrv_has_zero_init       = bdrv_has_zero_init_1,
-    .bdrv_co_block_status     = bdrv_qed_co_block_status,
-    .bdrv_co_readv            = bdrv_qed_co_readv,
-    .bdrv_co_writev           = bdrv_qed_co_writev,
-    .bdrv_co_pwrite_zeroes    = bdrv_qed_co_pwrite_zeroes,
-    .bdrv_co_truncate         = bdrv_qed_co_truncate,
-    .bdrv_co_getlength        = bdrv_qed_co_getlength,
-    .bdrv_co_get_info         = bdrv_qed_co_get_info,
-    .bdrv_refresh_limits      = bdrv_qed_refresh_limits,
-    .bdrv_change_backing_file = bdrv_qed_change_backing_file,
-    .bdrv_co_invalidate_cache = bdrv_qed_co_invalidate_cache,
-    .bdrv_co_check            = bdrv_qed_co_check,
-    .bdrv_detach_aio_context  = bdrv_qed_detach_aio_context,
-    .bdrv_attach_aio_context  = bdrv_qed_attach_aio_context,
-    .bdrv_drain_begin         = bdrv_qed_drain_begin,
+    .format_name                    = "qed",
+    .instance_size                  = sizeof(BDRVQEDState),
+    .create_opts                    = &qed_create_opts,
+    .is_format                      = true,
+    .supports_backing               = true,
+
+    .bdrv_probe                     = bdrv_qed_probe,
+    .bdrv_open                      = bdrv_qed_open,
+    .bdrv_close                     = bdrv_qed_close,
+    .bdrv_reopen_prepare            = bdrv_qed_reopen_prepare,
+    .bdrv_child_perm                = bdrv_default_perms,
+    .bdrv_co_create                 = bdrv_qed_co_create,
+    .bdrv_co_create_opts            = bdrv_qed_co_create_opts,
+    .bdrv_has_zero_init             = bdrv_has_zero_init_1,
+    .bdrv_co_block_status           = bdrv_qed_co_block_status,
+    .bdrv_co_readv                  = bdrv_qed_co_readv,
+    .bdrv_co_writev                 = bdrv_qed_co_writev,
+    .bdrv_co_pwrite_zeroes          = bdrv_qed_co_pwrite_zeroes,
+    .bdrv_co_truncate               = bdrv_qed_co_truncate,
+    .bdrv_co_getlength              = bdrv_qed_co_getlength,
+    .bdrv_co_get_info               = bdrv_qed_co_get_info,
+    .bdrv_refresh_limits            = bdrv_qed_refresh_limits,
+    .bdrv_co_change_backing_file    = bdrv_qed_co_change_backing_file,
+    .bdrv_co_invalidate_cache       = bdrv_qed_co_invalidate_cache,
+    .bdrv_co_check                  = bdrv_qed_co_check,
+    .bdrv_detach_aio_context        = bdrv_qed_detach_aio_context,
+    .bdrv_attach_aio_context        = bdrv_qed_attach_aio_context,
+    .bdrv_drain_begin               = bdrv_qed_drain_begin,
 };
 
 static void bdrv_qed_init(void)