diff mbox

[v13,06/14] block: Add backing_blocker in BlockDriverState

Message ID 1390972061-26560-7-git-send-email-famz@redhat.com
State New
Headers show

Commit Message

Fam Zheng Jan. 29, 2014, 5:07 a.m. UTC 
This makes use of op_blocker and blocks all the operations except for
commit target, on each BlockDriverState->backing_hd.

The asserts for op_blocker in bdrv_swap are removed because with this
change, the target of block commit has at least the backing blocker of
its child, so the assertion is not true. Callers should do their check.

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 block.c                   | 19 +++++++++++++++----
 include/block/block_int.h |  3 +++
 2 files changed, 18 insertions(+), 4 deletions(-)
diff mbox

Patch

diff --git a/block.c b/block.c
index c4eaa37..4e3b393 100644
--- a/block.c
+++ b/block.c
@@ -1075,19 +1075,33 @@  fail:
 void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd)
 {
     if (bs->backing_hd) {
+        assert(error_is_set(&bs->backing_blocker));
+        bdrv_op_unblock_all(bs->backing_hd, bs->backing_blocker);
         bdrv_unref(bs->backing_hd);
+    } else if (backing_hd) {
+        error_setg(&bs->backing_blocker,
+                   "device is used as backing hd of '%s'",
+                   bs->device_name);
     }
 
     bs->backing_hd = backing_hd;
     if (!backing_hd) {
         bs->backing_file[0] = '\0';
         bs->backing_format[0] = '\0';
+        if (error_is_set(&bs->backing_blocker)) {
+            error_free(bs->backing_blocker);
+        }
         goto out;
     }
     pstrcpy(bs->backing_file, sizeof(bs->backing_file), backing_hd->filename);
     pstrcpy(bs->backing_format, sizeof(bs->backing_file),
             backing_hd->drv ? backing_hd->drv->format_name : "");
     bdrv_ref(bs->backing_hd);
+
+    bdrv_op_block_all(bs->backing_hd, bs->backing_blocker);
+    /* Otherwise we won't be able to commit due to check in bdrv_commit */
+    bdrv_op_unblock(bs->backing_hd, BLOCK_OP_TYPE_COMMIT,
+                    bs->backing_blocker);
 out:
     bdrv_refresh_limits(bs);
 }
@@ -1675,8 +1689,7 @@  void bdrv_close(BlockDriverState *bs)
 
     if (bs->drv) {
         if (bs->backing_hd) {
-            bdrv_unref(bs->backing_hd);
-            bs->backing_hd = NULL;
+            bdrv_set_backing_hd(bs, NULL);
         }
         bs->drv->bdrv_close(bs);
         g_free(bs->opaque);
@@ -1878,7 +1891,6 @@  void bdrv_swap(BlockDriverState *bs_new, BlockDriverState *bs_old)
     assert(QLIST_EMPTY(&bs_new->dirty_bitmaps));
     assert(bs_new->job == NULL);
     assert(bs_new->dev == NULL);
-    assert(bdrv_op_blocker_is_empty(bs_new));
     assert(bs_new->io_limits_enabled == false);
     assert(!throttle_have_timer(&bs_new->throttle_state));
 
@@ -1897,7 +1909,6 @@  void bdrv_swap(BlockDriverState *bs_new, BlockDriverState *bs_old)
     /* Check a few fields that should remain attached to the device */
     assert(bs_new->dev == NULL);
     assert(bs_new->job == NULL);
-    assert(bdrv_op_blocker_is_empty(bs_new));
     assert(bs_new->io_limits_enabled == false);
     assert(!throttle_have_timer(&bs_new->throttle_state));
 
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 1d3f76f..1f4f78b 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -369,6 +369,9 @@  struct BlockDriverState {
     BlockJob *job;
 
     QDict *options;
+
+    /* The error object in use for blocking operations on backing_hd */
+    Error *backing_blocker;
 };
 
 int get_tmp_filename(char *filename, int size);