diff options
author | Fam Zheng <famz@redhat.com> | 2015-11-09 18:16:53 +0800 |
---|---|---|
committer | Kevin Wolf <kwolf@redhat.com> | 2015-11-12 16:22:43 +0100 |
commit | 67da1dc5ce696c7b309b1db100da7d94292847b7 (patch) | |
tree | c28226815e2d495cee3106dcf557667751adec10 /include | |
parent | 83c98d7b924eab36a0a2c7813731dbef439a91d3 (diff) |
block: Introduce BlockDriver.bdrv_drain callback
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.
Update the comments of bdrv_drain and bdrv_drained_begin accordingly.
Like bdrv_requests_pending(), we should consider all the children of bs.
Before, the while loop just works, as bdrv_requests_pending() already
tracks its children; now we mustn't miss the callback, so recurse down
explicitly.
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1447064214-29930-9-git-send-email-famz@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'include')
-rw-r--r-- | include/block/block_int.h | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/include/block/block_int.h b/include/block/block_int.h index 84991d9973..3a24913a7e 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -295,6 +295,12 @@ 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; }; |