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[Qemu-block] [PATCH v5 05/12] block: Introduce "drained begin/end" API
From: |
Fam Zheng |
Subject: |
[Qemu-block] [PATCH v5 05/12] block: Introduce "drained begin/end" API |
Date: |
Wed, 21 Oct 2015 10:06:42 +0800 |
The semantics is that after bdrv_drained_begin(bs), bs will not get new external
requests until the matching bdrv_drained_end(bs).
Signed-off-by: Fam Zheng <address@hidden>
---
block/io.c | 17 +++++++++++++++++
include/block/block.h | 21 +++++++++++++++++++++
include/block/block_int.h | 2 ++
3 files changed, 40 insertions(+)
diff --git a/block/io.c b/block/io.c
index 2fd7a1d..5ac6256 100644
--- a/block/io.c
+++ b/block/io.c
@@ -2624,3 +2624,20 @@ void bdrv_flush_io_queue(BlockDriverState *bs)
}
bdrv_start_throttled_reqs(bs);
}
+
+void bdrv_drained_begin(BlockDriverState *bs)
+{
+ if (!bs->quiesce_counter++) {
+ aio_disable_external(bdrv_get_aio_context(bs));
+ }
+ bdrv_drain(bs);
+}
+
+void bdrv_drained_end(BlockDriverState *bs)
+{
+ assert(bs->quiesce_counter > 0);
+ if (--bs->quiesce_counter > 0) {
+ return;
+ }
+ aio_enable_external(bdrv_get_aio_context(bs));
+}
diff --git a/include/block/block.h b/include/block/block.h
index 28d903c..6d38b62 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -610,4 +610,25 @@ void bdrv_io_plug(BlockDriverState *bs);
void bdrv_io_unplug(BlockDriverState *bs);
void bdrv_flush_io_queue(BlockDriverState *bs);
+BlockAcctStats *bdrv_get_stats(BlockDriverState *bs);
+
+/**
+ * bdrv_drained_begin:
+ *
+ * Begin a quiesced section for exclusive access to the BDS, by disabling
+ * external request sources including NBD server and device model. Note that
+ * this doesn't block timers or coroutines from submitting more requests, which
+ * means block_job_pause is still necessary.
+ *
+ * This function can be recursive.
+ */
+void bdrv_drained_begin(BlockDriverState *bs);
+
+/**
+ * bdrv_drained_end:
+ *
+ * End a quiescent section started by bdrv_drained_begin().
+ */
+void bdrv_drained_end(BlockDriverState *bs);
+
#endif
diff --git a/include/block/block_int.h b/include/block/block_int.h
index e472a03..e317b14 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -448,6 +448,8 @@ struct BlockDriverState {
/* threshold limit for writes, in bytes. "High water mark". */
uint64_t write_threshold_offset;
NotifierWithReturn write_threshold_notifier;
+
+ int quiesce_counter;
};
struct BlockBackendRootState {
--
2.4.3
- [Qemu-block] [PATCH v5 00/12] block: Protect nested event loop with bdrv_drained_begin and bdrv_drained_end, Fam Zheng, 2015/10/20
- [Qemu-block] [PATCH v5 05/12] block: Introduce "drained begin/end" API,
Fam Zheng <=
- [Qemu-block] [PATCH v5 06/12] block: Add "drained begin/end" for transactional external snapshot, Fam Zheng, 2015/10/20
- [Qemu-block] [PATCH v5 07/12] block: Add "drained begin/end" for transactional backup, Fam Zheng, 2015/10/20
- [Qemu-block] [PATCH v5 08/12] block: Add "drained begin/end" for transactional blockdev-backup, Fam Zheng, 2015/10/20
- [Qemu-block] [PATCH v5 09/12] block: Add "drained begin/end" for internal snapshot, Fam Zheng, 2015/10/20