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[Qemu-block] [PATCH v2 10/12] block: Introduce BlockDriver.bdrv_drain ca
From: |
Fam Zheng |
Subject: |
[Qemu-block] [PATCH v2 10/12] block: Introduce BlockDriver.bdrv_drain callback |
Date: |
Mon, 12 Oct 2015 19:50:49 +0800 |
Drivers can have internal request sources that generate IO, like the
need_check_timer in QED. Since we want quiesced periods that contain
nested event loops in block layer, we need to have a way to disable such
event sources.
Block drivers must implement the "bdrv_drain" callback if it has any
internal sources that can generate I/O activity, like a timer or a
worker thread (even in a library) that can schedule QEMUBH in an
asynchronous callback.
Signed-off-by: Fam Zheng <address@hidden>
---
block/io.c | 3 +++
include/block/block_int.h | 6 ++++++
2 files changed, 9 insertions(+)
diff --git a/block/io.c b/block/io.c
index 5c088d5..0e6d77c 100644
--- a/block/io.c
+++ b/block/io.c
@@ -247,6 +247,9 @@ void bdrv_drain(BlockDriverState *bs)
{
bool busy = true;
+ if (bs->drv && bs->drv->bdrv_drain) {
+ bs->drv->bdrv_drain(bs);
+ }
while (busy) {
/* Keep iterating */
bdrv_flush_io_queue(bs);
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 7c58221..99359b2 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -288,6 +288,12 @@ struct BlockDriver {
*/
int (*bdrv_probe_geometry)(BlockDriverState *bs, HDGeometry *geo);
+ /**
+ * Drain and stop any internal sources of requests in the driver, and
+ * remain so until next I/O callback (e.g. bdrv_co_writev) is called.
+ */
+ void (*bdrv_drain)(BlockDriverState *bs);
+
QLIST_ENTRY(BlockDriver) list;
};
--
2.6.1
- [Qemu-block] [PATCH v2 05/12] block: Introduce "drained begin/end" API, (continued)
[Qemu-block] [PATCH v2 08/12] block: Add "drained begin/end" for transactional blockdev-backup, Fam Zheng, 2015/10/12
[Qemu-block] [PATCH v2 07/12] block: Add "drained begin/end" for transactional backup, Fam Zheng, 2015/10/12
[Qemu-block] [PATCH v2 11/12] qed: Implement .bdrv_drain, Fam Zheng, 2015/10/12
[Qemu-block] [PATCH v2 10/12] block: Introduce BlockDriver.bdrv_drain callback,
Fam Zheng <=
[Qemu-block] [PATCH v2 12/12] tests: Add test case for aio_disable_external, Fam Zheng, 2015/10/12
[Qemu-block] [PATCH v2 01/12] aio: Add "is_external" flag for event handlers, Fam Zheng, 2015/10/15
[Qemu-block] [PATCH v2 02/12] nbd: Mark fd handlers client type as "external", Fam Zheng, 2015/10/15
[Qemu-block] [PATCH v2 06/12] block: Add "drained begin/end" for transactional external snapshot, Fam Zheng, 2015/10/15
[Qemu-block] [PATCH v2 09/12] block: Add "drained begin/end" for internal snapshot, Fam Zheng, 2015/10/15