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block: Make bdrv_drain() driver callbacks non-recursive 

bdrv_drained_begin() doesn't increase bs->quiesce_counter recursively
and also doesn't notify other parent nodes of children, which both means
that the child nodes are not actually drained, and bdrv_drained_begin()
is providing useful functionality only on a single node.

To keep things consistent, we also shouldn't call the block driver
callbacks recursively.

A proper recursive drain version that provides an actually working
drained section for child nodes will be introduced later.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
This commit is contained in:
Kevin Wolf 2017-12-07 12:20:10 +01:00
parent 9a7e86c804
commit 7b6a3d3553
1 changed files with 9 additions and 7 deletions
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16
block/io.c
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@ -158,7 +158,7 @@ static void coroutine_fn bdrv_drain_invoke_entry(void *opaque)
} }
/* Recursively call BlockDriver.bdrv_co_drain_begin/end callbacks */ /* Recursively call BlockDriver.bdrv_co_drain_begin/end callbacks */
static void bdrv_drain_invoke(BlockDriverState *bs, bool begin) static void bdrv_drain_invoke(BlockDriverState *bs, bool begin, bool recursive)
{ {
BdrvChild *child, *tmp; BdrvChild *child, *tmp;
BdrvCoDrainData data = { .bs = bs, .done = false, .begin = begin}; BdrvCoDrainData data = { .bs = bs, .done = false, .begin = begin};
@ -172,8 +172,10 @@ static void bdrv_drain_invoke(BlockDriverState *bs, bool begin)
bdrv_coroutine_enter(bs, data.co); bdrv_coroutine_enter(bs, data.co);
BDRV_POLL_WHILE(bs, !data.done); BDRV_POLL_WHILE(bs, !data.done);
QLIST_FOREACH_SAFE(child, &bs->children, next, tmp) { if (recursive) {
bdrv_drain_invoke(child->bs, begin); QLIST_FOREACH_SAFE(child, &bs->children, next, tmp) {
bdrv_drain_invoke(child->bs, begin, true);
}
} }
} }
@ -265,7 +267,7 @@ void bdrv_drained_begin(BlockDriverState *bs)
bdrv_parent_drained_begin(bs); bdrv_parent_drained_begin(bs);
} }
bdrv_drain_invoke(bs, true); bdrv_drain_invoke(bs, true, false);
bdrv_drain_recurse(bs); bdrv_drain_recurse(bs);
} }
@ -281,7 +283,7 @@ void bdrv_drained_end(BlockDriverState *bs)
} }
/* Re-enable things in child-to-parent order */ /* Re-enable things in child-to-parent order */
bdrv_drain_invoke(bs, false); bdrv_drain_invoke(bs, false, false);
bdrv_parent_drained_end(bs); bdrv_parent_drained_end(bs);
aio_enable_external(bdrv_get_aio_context(bs)); aio_enable_external(bdrv_get_aio_context(bs));
} }
@ -345,7 +347,7 @@ void bdrv_drain_all_begin(void)
aio_context_acquire(aio_context); aio_context_acquire(aio_context);
aio_disable_external(aio_context); aio_disable_external(aio_context);
bdrv_parent_drained_begin(bs); bdrv_parent_drained_begin(bs);
bdrv_drain_invoke(bs, true); bdrv_drain_invoke(bs, true, true);
aio_context_release(aio_context); aio_context_release(aio_context);
if (!g_slist_find(aio_ctxs, aio_context)) { if (!g_slist_find(aio_ctxs, aio_context)) {
@ -388,7 +390,7 @@ void bdrv_drain_all_end(void)
/* Re-enable things in child-to-parent order */ /* Re-enable things in child-to-parent order */
aio_context_acquire(aio_context); aio_context_acquire(aio_context);
bdrv_drain_invoke(bs, false); bdrv_drain_invoke(bs, false, true);
bdrv_parent_drained_end(bs); bdrv_parent_drained_end(bs);
aio_enable_external(aio_context); aio_enable_external(aio_context);
aio_context_release(aio_context); aio_context_release(aio_context);