mirror: correct buf_size

If bus_size is less than 0, the command fails.
If buf_size is 0, use DEFAULT_MIRROR_BUF_SIZE.
If buf_size % granularity is not 0, mirror_free_init() will
do dangerous things.
Signed-off-by: NWen Congyang <wency@cn.fujitsu.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Message-id: 5555A588.3080907@cn.fujitsu.com
Signed-off-by: NJeff Cody <jcody@redhat.com>

block/mirror.c

@@ -20,6 +20,7 @@
 
 #define SLICE_TIME    100000000ULL /* ns */
 #define MAX_IN_FLIGHT 16
+#define DEFAULT_MIRROR_BUF_SIZE   (10 << 20)
 
 /* The mirroring buffer is a list of granularity-sized chunks.
  * Free chunks are organized in a list.
@@ -701,6 +702,14 @@ static void mirror_start_job(BlockDriverState *bs, BlockDriverState *target,
         return;
     }
 
+    if (buf_size < 0) {
+        error_setg(errp, "Invalid parameter 'buf-size'");
+        return;
+    }
+
+    if (buf_size == 0) {
+        buf_size = DEFAULT_MIRROR_BUF_SIZE;
+    }
 
     s = block_job_create(driver, bs, speed, cb, opaque, errp);
     if (!s) {
@@ -714,7 +723,7 @@ static void mirror_start_job(BlockDriverState *bs, BlockDriverState *target,
     s->is_none_mode = is_none_mode;
     s->base = base;
     s->granularity = granularity;
-    s->buf_size = MAX(buf_size, granularity);
+    s->buf_size = ROUND_UP(buf_size, granularity);
     s->unmap = unmap;
 
     s->dirty_bitmap = bdrv_create_dirty_bitmap(bs, granularity, NULL, errp);

blockdev.c

@@ -2639,8 +2639,6 @@ out:
     aio_context_release(aio_context);
 }
 
-#define DEFAULT_MIRROR_BUF_SIZE   (10 << 20)
-
 void qmp_drive_mirror(const char *device, const char *target,
                       bool has_format, const char *format,
                       bool has_node_name, const char *node_name,
@@ -2682,7 +2680,7 @@ void qmp_drive_mirror(const char *device, const char *target,
         granularity = 0;
     }
     if (!has_buf_size) {
-        buf_size = DEFAULT_MIRROR_BUF_SIZE;
+        buf_size = 0;
     }
     if (!has_unmap) {
         unmap = true;