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[Qemu-devel] [PULL 48/53] block: add bdrv_drain()
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PULL 48/53] block: add bdrv_drain() |
Date: |
Mon, 3 Nov 2014 11:50:51 +0000 |
Now that op blockers are in use, we can ensure that no other sources are
generating I/O on a BlockDriverState. Therefore it is possible to drain
requests for a single BDS.
Signed-off-by: Stefan Hajnoczi <address@hidden>
Reviewed-by: Max Reitz <address@hidden>
Message-id: address@hidden
---
block.c | 36 +++++++++++++++++++++++++++++-------
include/block/block.h | 1 +
2 files changed, 30 insertions(+), 7 deletions(-)
diff --git a/block.c b/block.c
index c5ff560..a909b9d 100644
--- a/block.c
+++ b/block.c
@@ -1904,6 +1904,34 @@ static bool bdrv_requests_pending(BlockDriverState *bs)
return false;
}
+static bool bdrv_drain_one(BlockDriverState *bs)
+{
+ bool bs_busy;
+
+ bdrv_flush_io_queue(bs);
+ bdrv_start_throttled_reqs(bs);
+ bs_busy = bdrv_requests_pending(bs);
+ bs_busy |= aio_poll(bdrv_get_aio_context(bs), bs_busy);
+ return bs_busy;
+}
+
+/*
+ * Wait for pending requests to complete on a single BlockDriverState subtree
+ *
+ * See the warning in bdrv_drain_all(). This function can only be called if
+ * you are sure nothing can generate I/O because you have op blockers
+ * installed.
+ *
+ * Note that unlike bdrv_drain_all(), the caller must hold the BlockDriverState
+ * AioContext.
+ */
+void bdrv_drain(BlockDriverState *bs)
+{
+ while (bdrv_drain_one(bs)) {
+ /* Keep iterating */
+ }
+}
+
/*
* Wait for pending requests to complete across all BlockDriverStates
*
@@ -1927,16 +1955,10 @@ void bdrv_drain_all(void)
QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
AioContext *aio_context = bdrv_get_aio_context(bs);
- bool bs_busy;
aio_context_acquire(aio_context);
- bdrv_flush_io_queue(bs);
- bdrv_start_throttled_reqs(bs);
- bs_busy = bdrv_requests_pending(bs);
- bs_busy |= aio_poll(aio_context, bs_busy);
+ busy |= bdrv_drain_one(bs);
aio_context_release(aio_context);
-
- busy |= bs_busy;
}
}
}
diff --git a/include/block/block.h b/include/block/block.h
index 5d13282..13e4537 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -334,6 +334,7 @@ int bdrv_flush(BlockDriverState *bs);
int coroutine_fn bdrv_co_flush(BlockDriverState *bs);
int bdrv_flush_all(void);
void bdrv_close_all(void);
+void bdrv_drain(BlockDriverState *bs);
void bdrv_drain_all(void);
int bdrv_discard(BlockDriverState *bs, int64_t sector_num, int nb_sectors);
--
1.9.3
- [Qemu-devel] [PULL 38/53] qemu-img: Fix insignificant memleak, (continued)
- [Qemu-devel] [PULL 38/53] qemu-img: Fix insignificant memleak, Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 39/53] block/qcow2: Implement status CB for amend, Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 40/53] block/qcow2: Make get_refcount() global, Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 41/53] block/qcow2: Simplify shared L2 handling in amend, Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 42/53] iotests: Expand test 061, Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 43/53] block: acquire AioContext in generic blockjob QMP commands, Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 44/53] blockdev: acquire AioContext in do_qmp_query_block_jobs_one(), Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 45/53] blockdev: acquire AioContext in blockdev_mark_auto_del(), Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 46/53] blockdev: add note that block_job_cb() must be thread-safe, Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 47/53] blockjob: add block_job_defer_to_main_loop(), Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 48/53] block: add bdrv_drain(),
Stefan Hajnoczi <=
- [Qemu-devel] [PULL 49/53] block: let backup blockjob run in BDS AioContext, Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 50/53] block: let stream blockjob run in BDS AioContext, Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 52/53] block: let commit blockjob run in BDS AioContext, Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 53/53] block: declare blockjobs and dataplane friends!, Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 51/53] block: let mirror blockjob run in BDS AioContext, Stefan Hajnoczi, 2014/11/03
- Re: [Qemu-devel] [PULL 00/53] Block patches, Peter Maydell, 2014/11/03