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[Qemu-block] [PULL 32/37] block: Introduce "drained begin/end" API
From: |
Kevin Wolf |
Subject: |
[Qemu-block] [PULL 32/37] block: Introduce "drained begin/end" API |
Date: |
Fri, 23 Oct 2015 19:01:19 +0200 |
From: Fam Zheng <address@hidden>
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>
Signed-off-by: Kevin Wolf <address@hidden>
---
block/io.c | 17 +++++++++++++++++
include/block/block.h | 19 +++++++++++++++++++
include/block/block_int.h | 2 ++
3 files changed, 38 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 77e91bd..610db92 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -610,4 +610,23 @@ void bdrv_io_plug(BlockDriverState *bs);
void bdrv_io_unplug(BlockDriverState *bs);
void bdrv_flush_io_queue(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 7b76eea..3ceeb5a 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 {
--
1.8.3.1
- [Qemu-block] [PULL 16/37] block: Move I/O status and error actions into BB, (continued)
- [Qemu-block] [PULL 16/37] block: Move I/O status and error actions into BB, Kevin Wolf, 2015/10/23
- [Qemu-block] [PULL 22/37] block: Add blk_insert_bs(), Kevin Wolf, 2015/10/23
- [Qemu-block] [PULL 19/37] block: Make some BB functions fall back to BBRS, Kevin Wolf, 2015/10/23
- [Qemu-block] [PULL 20/37] block: Fail requests to empty BlockBackend, Kevin Wolf, 2015/10/23
- [Qemu-block] [PULL 24/37] blockdev: Do not create BDS for empty drive, Kevin Wolf, 2015/10/23
- [Qemu-block] [PULL 23/37] block: Prepare for NULL BDS, Kevin Wolf, 2015/10/23
- [Qemu-block] [PULL 27/37] throttle: Remove throttle_group_lock/unlock(), Kevin Wolf, 2015/10/23
- [Qemu-block] [PULL 26/37] blockdev: Allow more options for BB-less BDS tree, Kevin Wolf, 2015/10/23
- [Qemu-block] [PULL 25/37] blockdev: Pull out blockdev option extraction, Kevin Wolf, 2015/10/23
- [Qemu-block] [PULL 31/37] aio: introduce aio_{disable, enable}_external, Kevin Wolf, 2015/10/23
- [Qemu-block] [PULL 32/37] block: Introduce "drained begin/end" API,
Kevin Wolf <=
- [Qemu-block] [PULL 29/37] nbd: Mark fd handlers client type as "external", Kevin Wolf, 2015/10/23
- [Qemu-block] [PULL 36/37] block: Add "drained begin/end" for internal snapshot, Kevin Wolf, 2015/10/23
- [Qemu-block] [PULL 30/37] dataplane: Mark host notifiers' client type as "external", Kevin Wolf, 2015/10/23
- [Qemu-block] [PULL 28/37] aio: Add "is_external" flag for event handlers, Kevin Wolf, 2015/10/23
- [Qemu-block] [PULL 34/37] block: Add "drained begin/end" for transactional backup, Kevin Wolf, 2015/10/23
- [Qemu-block] [PULL 37/37] tests: Add test case for aio_disable_external, Kevin Wolf, 2015/10/23
- [Qemu-block] [PULL 35/37] block: Add "drained begin/end" for transactional blockdev-backup, Kevin Wolf, 2015/10/23
- [Qemu-block] [PULL 33/37] block: Add "drained begin/end" for transactional external snapshot, Kevin Wolf, 2015/10/23
- Re: [Qemu-block] [Qemu-devel] [PULL 00/37] Block layer patches, Peter Maydell, 2015/10/26