block: convert bdrv_invalidate_cache callback to coroutine_fn

QED's bdrv_invalidate_cache implementation would like to reuse functions
that acquire/release the metadata locks.  Call it from coroutine context
to simplify the logic.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1516279431-30424-6-git-send-email-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 37 insertions, 4 deletions

diff --git a/block.c b/block.c
index 4f76714f6b..603befb325 100644
--- a/block.c
+++ b/block.c
@@ -4209,7 +4209,8 @@ void bdrv_init_with_whitelist(void)
     bdrv_init();
 }
 
-void bdrv_invalidate_cache(BlockDriverState *bs, Error **errp)
+static void coroutine_fn bdrv_co_invalidate_cache(BlockDriverState *bs,
+                                                  Error **errp)
 {
     BdrvChild *child, *parent;
     uint64_t perm, shared_perm;
@@ -4225,7 +4226,7 @@ void bdrv_invalidate_cache(BlockDriverState *bs, Error **errp)
     }
 
     QLIST_FOREACH(child, &bs->children, next) {
-        bdrv_invalidate_cache(child->bs, &local_err);
+        bdrv_co_invalidate_cache(child->bs, &local_err);
         if (local_err) {
             error_propagate(errp, local_err);
             return;
@@ -4255,8 +4256,8 @@ void bdrv_invalidate_cache(BlockDriverState *bs, Error **errp)
     }
     bdrv_set_perm(bs, perm, shared_perm);
 
-    if (bs->drv->bdrv_invalidate_cache) {
-        bs->drv->bdrv_invalidate_cache(bs, &local_err);
+    if (bs->drv->bdrv_co_invalidate_cache) {
+        bs->drv->bdrv_co_invalidate_cache(bs, &local_err);
         if (local_err) {
             bs->open_flags |= BDRV_O_INACTIVE;
             error_propagate(errp, local_err);
@@ -4282,6 +4283,38 @@ void bdrv_invalidate_cache(BlockDriverState *bs, Error **errp)
     }
 }
 
+typedef struct InvalidateCacheCo {
+    BlockDriverState *bs;
+    Error **errp;
+    bool done;
+} InvalidateCacheCo;
+
+static void coroutine_fn bdrv_invalidate_cache_co_entry(void *opaque)
+{
+    InvalidateCacheCo *ico = opaque;
+    bdrv_co_invalidate_cache(ico->bs, ico->errp);
+    ico->done = true;
+}
+
+void bdrv_invalidate_cache(BlockDriverState *bs, Error **errp)
+{
+    Coroutine *co;
+    InvalidateCacheCo ico = {
+        .bs = bs,
+        .done = false,
+        .errp = errp
+    };
+
+    if (qemu_in_coroutine()) {
+        /* Fast-path if already in coroutine context */
+        bdrv_invalidate_cache_co_entry(&ico);
+    } else {
+        co = qemu_coroutine_create(bdrv_invalidate_cache_co_entry, &ico);
+        qemu_coroutine_enter(co);
+        BDRV_POLL_WHILE(bs, !ico.done);
+    }
+}
+
 void bdrv_invalidate_cache_all(Error **errp)
 {
     BlockDriverState *bs;