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authorFam Zheng <famz@redhat.com>2015-10-23 11:08:09 +0800
committerKevin Wolf <kwolf@redhat.com>2015-10-23 18:18:24 +0200
commit51288d7917e5c5b088985aaa7ff3592561fbc2ba (patch)
tree53511dc975f9f608dc4cc8e073c81055ba3565b0 /include/block
parentc1e1e5fa8f25f9061b076a05045a6d4950d1a891 (diff)
downloadhqemu-51288d7917e5c5b088985aaa7ff3592561fbc2ba.zip
hqemu-51288d7917e5c5b088985aaa7ff3592561fbc2ba.tar.gz
block: Introduce "drained begin/end" API
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 <famz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'include/block')
-rw-r--r--include/block/block.h19
-rw-r--r--include/block/block_int.h2
2 files changed, 21 insertions, 0 deletions
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 {
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