[Qemu-devel] [PATCH 1/2] block: acquire AioContext in qmp_block_resize()

[Stefan Hajnoczi]

Make block_resize safe for dataplane where another thread may be running
the BlockDriverState's AioContext.

Signed-off-by: Stefan Hajnoczi <address@hidden>
---
 blockdev.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/blockdev.c b/blockdev.c
index 48bd9a3..197b799 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1799,6 +1799,7 @@ void qmp_block_resize(bool has_device, const char *device,
 {
     Error *local_err = NULL;
     BlockDriverState *bs;
+    AioContext *aio_context;
     int ret;
 
     bs = bdrv_lookup_bs(has_device ? device : NULL,
@@ -1809,19 +1810,22 @@ void qmp_block_resize(bool has_device, const char 
*device,
         return;
     }
 
+    aio_context = bdrv_get_aio_context(bs);
+    aio_context_acquire(aio_context);
+
     if (!bdrv_is_first_non_filter(bs)) {
         error_set(errp, QERR_FEATURE_DISABLED, "resize");
-        return;
+        goto out;
     }
 
     if (size < 0) {
         error_set(errp, QERR_INVALID_PARAMETER_VALUE, "size", "a >0 size");
-        return;
+        goto out;
     }
 
     if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_RESIZE, NULL)) {
         error_set(errp, QERR_DEVICE_IN_USE, device);
-        return;
+        goto out;
     }
 
     /* complete all in-flight operations before resizing the device */
@@ -1847,6 +1851,9 @@ void qmp_block_resize(bool has_device, const char *device,
         error_setg_errno(errp, -ret, "Could not resize");
         break;
     }
+
+out:
+    aio_context_release(aio_context);
 }
 
 static void block_job_cb(void *opaque, int ret)
-- 
1.9.3