diff mbox

[7/7] block: Add backing_blocker in BlockDriverState

Message ID 1400815403-7719-8-git-send-email-famz@redhat.com
State New
Headers show

Commit Message

Fam Zheng May 23, 2014, 3:23 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                   | 22 ++++++++++++++++++----
 block/mirror.c            |  2 +-
 include/block/block_int.h |  3 +++
 3 files changed, 22 insertions(+), 5 deletions(-)

Comments

Stefan Hajnoczi May 23, 2014, 12:46 p.m. UTC | #1 
On Fri, May 23, 2014 at 11:23:23AM +0800, Fam Zheng wrote:
> 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                   | 22 ++++++++++++++++++----
>  block/mirror.c            |  2 +-
>  include/block/block_int.h |  3 +++
>  3 files changed, 22 insertions(+), 5 deletions(-)
> 
> diff --git a/block.c b/block.c
> index 91c866c..b5aeca2 100644
> --- a/block.c
> +++ b/block.c
> @@ -1097,14 +1097,29 @@ fail:
>  void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd)
>  {
>  
> +    if (bs->backing_hd) {
> +        assert(bs->backing_blocker);
> +        bdrv_op_unblock_all(bs->backing_hd, bs->backing_blocker);
> +    } 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) {
> +        error_free(bs->backing_blocker);

bs->backing_block = NULL;

...to make the assert(bs->backing_blocker) above more useful.
diff mbox

Patch

diff --git a/block.c b/block.c
index 91c866c..b5aeca2 100644
--- a/block.c
+++ b/block.c
@@ -1097,14 +1097,29 @@  fail:
 void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd)
 {
 
+    if (bs->backing_hd) {
+        assert(bs->backing_blocker);
+        bdrv_op_unblock_all(bs->backing_hd, bs->backing_blocker);
+    } 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) {
+        error_free(bs->backing_blocker);
         goto out;
     }
     bs->open_flags &= ~BDRV_O_NO_BACKING;
     pstrcpy(bs->backing_file, sizeof(bs->backing_file), backing_hd->filename);
     pstrcpy(bs->backing_format, sizeof(bs->backing_format),
             backing_hd->drv ? backing_hd->drv->format_name : "");
+
+    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);
 }
@@ -1803,8 +1818,9 @@  void bdrv_close(BlockDriverState *bs)
 
     if (bs->drv) {
         if (bs->backing_hd) {
-            bdrv_unref(bs->backing_hd);
-            bs->backing_hd = NULL;
+            BlockDriverState *backing_hd = bs->backing_hd;
+            bdrv_set_backing_hd(bs, NULL);
+            bdrv_unref(backing_hd);
         }
         bs->drv->bdrv_close(bs);
         g_free(bs->opaque);
@@ -2006,7 +2022,6 @@  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));
 
@@ -2025,7 +2040,6 @@  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/block/mirror.c b/block/mirror.c
index 1c38aa8..94c8661 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -498,7 +498,7 @@  immediate_exit:
             /* drop the bs loop chain formed by the swap: break the loop then
              * trigger the unref from the top one */
             BlockDriverState *p = s->base->backing_hd;
-            s->base->backing_hd = NULL;
+            bdrv_set_backing_hd(s->base, NULL);
             bdrv_unref(p);
         }
     }
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 7b1c013..f2e753f 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -369,6 +369,9 @@  struct BlockDriverState {
 
     QDict *options;
     BlockdevDetectZeroesOptions detect_zeroes;
+
+    /* The error object in use for blocking operations on backing_hd */
+    Error *backing_blocker;
 };
 
 int get_tmp_filename(char *filename, int size);