openkylin
/
qemu
mirror of https://gitee.com/openkylin/qemu.git
9
0
Fork 0
Code Issues Projects Releases Wiki Activity

block: Unify order in drain functions 

Drain requests are propagated to child nodes, parent nodes and directly
to the AioContext. The order in which this happened was different
between all combinations of drain/drain_all and begin/end.

The correct order is to keep children only drained when their parents
are also drained. This means that at the start of a drained section, the
AioContext needs to be drained first, the parents second and only then
the children. The correct order for the end of a drained section is the
opposite.

This patch changes the three other functions to follow the example of
bdrv_drained_begin(), which is the only one that got it right.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Kevin Wolf 2017-12-06 11:00:59 +01:00
parent 5280aa32e1
commit 60369b86c4
1 changed files with 8 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
block/io.c
View File

@ -277,6 +277,7 @@ void bdrv_drained_begin(BlockDriverState *bs)
return;
}
/* Stop things in parent-to-child order */
if (atomic_fetch_inc(&bs->quiesce_counter) == 0) {
aio_disable_external(bdrv_get_aio_context(bs));
bdrv_parent_drained_begin(bs);
@ -297,8 +298,9 @@ void bdrv_drained_end(BlockDriverState *bs)
return;
}
bdrv_parent_drained_end(bs);
/* Re-enable things in child-to-parent order */
bdrv_drain_invoke(bs, false);
bdrv_parent_drained_end(bs);
aio_enable_external(bdrv_get_aio_context(bs));
}
@ -351,9 +353,10 @@ void bdrv_drain_all_begin(void)
for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
AioContext *aio_context = bdrv_get_aio_context(bs);
/* Stop things in parent-to-child order */
aio_context_acquire(aio_context);
bdrv_parent_drained_begin(bs);
aio_disable_external(aio_context);
bdrv_parent_drained_begin(bs);
bdrv_drain_invoke(bs, true);
aio_context_release(aio_context);
@ -395,10 +398,11 @@ void bdrv_drain_all_end(void)
for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
AioContext *aio_context = bdrv_get_aio_context(bs);
/* Re-enable things in child-to-parent order */
aio_context_acquire(aio_context);
aio_enable_external(aio_context);
bdrv_parent_drained_end(bs);
bdrv_drain_invoke(bs, false);
bdrv_parent_drained_end(bs);
aio_enable_external(aio_context);
aio_context_release(aio_context);
}