[Qemu-block] [RFC PATCH 7/7] blockdev: Add "device IO" op blocker during snapshot transaction

[Fam Zheng]

Signed-off-by: Fam Zheng <f...@redhat.com>
---
 blockdev.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/blockdev.c b/blockdev.c
index 5eaf77e..859fa2e 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1398,6 +1398,7 @@ typedef struct ExternalSnapshotState {
     BlockDriverState *old_bs;
     BlockDriverState *new_bs;
     AioContext *aio_context;
+    Error *blocker;
 } ExternalSnapshotState;
 
 static void external_snapshot_prepare(BlkTransactionState *common,
@@ -1519,6 +1520,9 @@ static void external_snapshot_prepare(BlkTransactionState 
*common,
     if (ret != 0) {
         error_propagate(errp, local_err);
     }
+
+    error_setg(&state->blocker, "snapshot in progress");
+    bdrv_op_block(state->old_bs, BLOCK_OP_TYPE_DEVICE_IO, state->blocker);
 }
 
 static void external_snapshot_commit(BlkTransactionState *common)
@@ -1536,6 +1540,9 @@ static void external_snapshot_commit(BlkTransactionState 
*common)
     bdrv_reopen(state->new_bs, state->new_bs->open_flags & ~BDRV_O_RDWR,
                 NULL);
 
+    bdrv_op_unblock(state->old_bs, BLOCK_OP_TYPE_DEVICE_IO, state->blocker);
+    error_free(state->blocker);
+
     aio_context_release(state->aio_context);
 }
 
-- 
1.9.3