BDS users can register a notifier and get notified about op blocker
changes.
Signed-off-by: Fam Zheng <f...@redhat.com>
Reviewed-by: Max Reitz <mre...@redhat.com>
---
block.c | 35 +++++++++++++++++++++++++++++++++++
include/block/block.h | 8 ++++++++
include/block/block_int.h | 3 +++
3 files changed, 46 insertions(+)
diff --git a/block.c b/block.c
index 7904098..9714603 100644
--- a/block.c
+++ b/block.c
@@ -3375,6 +3375,19 @@ struct BdrvOpBlocker {
QLIST_ENTRY(BdrvOpBlocker) list;
};
+/* Add a notifier which will be notified when the first blocker of some type is
+ * added to bs, or when the last blocker is removed. The notifier handler
+ * should receive a BlockOpEvent data.
+ *
+ * Caller must hold bs->aio_context; the notifier handler is also called with
+ * it held.
+ */
+void bdrv_op_blocker_add_notifier(BlockDriverState *bs,
+ Notifier *notifier)
+{
+ notifier_list_add(&bs->op_blocker_notifiers, notifier);
+}
+
bool bdrv_op_is_blocked(BlockDriverState *bs, BlockOpType op, Error **errp)
{
BdrvOpBlocker *blocker;
@@ -3391,26 +3404,48 @@ bool bdrv_op_is_blocked(BlockDriverState *bs,
BlockOpType op, Error **errp)
return false;
}
+static void bdrv_op_blocker_notify(BlockDriverState *bs, BlockOpType op,
+ Error *reason, bool blocking)
+{
+ BlockOpEvent event = (BlockOpEvent) {
+ op = op,
+ reason = reason,
+ blocking = blocking,
+ };
+
+ notifier_list_notify(&bs->op_blocker_notifiers, &event);
+}
+
void bdrv_op_block(BlockDriverState *bs, BlockOpType op, Error *reason)
{
+ bool blocked;
BdrvOpBlocker *blocker;
assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX);
blocker = g_new0(BdrvOpBlocker, 1);
blocker->reason = reason;
+ blocked = !QLIST_EMPTY(&bs->op_blockers[op]);
QLIST_INSERT_HEAD(&bs->op_blockers[op], blocker, list);
+ if (!blocked) {
+ bdrv_op_blocker_notify(bs, op, reason, true);
+ }
}
void bdrv_op_unblock(BlockDriverState *bs, BlockOpType op, Error *reason)
{
+ bool blocked;
BdrvOpBlocker *blocker, *next;
assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX);
+ blocked = !QLIST_EMPTY(&bs->op_blockers[op]);
QLIST_FOREACH_SAFE(blocker, &bs->op_blockers[op], list, next) {
if (blocker->reason == reason) {
QLIST_REMOVE(blocker, list);
g_free(blocker);
}
}
+ if (blocked && QLIST_EMPTY(&bs->op_blockers[op])) {
+ bdrv_op_blocker_notify(bs, op, reason, false);
+ }
}
void bdrv_op_block_all(BlockDriverState *bs, Error *reason)
diff --git a/include/block/block.h b/include/block/block.h
index 906fb31..3420b2c 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -163,6 +163,12 @@ typedef enum BlockOpType {
BLOCK_OP_TYPE_MAX,
} BlockOpType;
+typedef struct {
+ BlockOpType type;
+ Error *reason;
+ bool blocking;
+} BlockOpEvent;
+
void bdrv_iostatus_enable(BlockDriverState *bs);
void bdrv_iostatus_reset(BlockDriverState *bs);
void bdrv_iostatus_disable(BlockDriverState *bs);
@@ -491,6 +497,8 @@ void bdrv_disable_copy_on_read(BlockDriverState *bs);
void bdrv_ref(BlockDriverState *bs);
void bdrv_unref(BlockDriverState *bs);
+void bdrv_op_blocker_add_notifier(BlockDriverState *bs,
+ Notifier *notifier);
bool bdrv_op_is_blocked(BlockDriverState *bs, BlockOpType op, Error **errp);
void bdrv_op_block(BlockDriverState *bs, BlockOpType op, Error *reason);
void bdrv_op_unblock(BlockDriverState *bs, BlockOpType op, Error *reason);
diff --git a/include/block/block_int.h b/include/block/block_int.h
index db29b74..29d1c84 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -418,6 +418,9 @@ struct BlockDriverState {
/* operation blockers */
QLIST_HEAD(, BdrvOpBlocker) op_blockers[BLOCK_OP_TYPE_MAX];
+ /* Callback when one list in op_blockers has "empty" status change. */
+ NotifierList op_blocker_notifiers;
+
/* long-running background operation */
BlockJob *job;
--
2.4.1
