Commit 7b6a3d35 authored by Kevin Wolf's avatar Kevin Wolf
Browse files

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: default avatarKevin Wolf <kwolf@redhat.com>
Reviewed-by: default avatarFam Zheng <famz@redhat.com>
parent 9a7e86c8

block/io.c

+9 −7
Original line number Diff line number Diff line
@@ -158,7 +158,7 @@ static void coroutine_fn bdrv_drain_invoke_entry(void *opaque) 
}



/* 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;

    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_POLL_WHILE(bs, !data.done);



    if (recursive) {

        QLIST_FOREACH_SAFE(child, &bs->children, next, tmp) {

        bdrv_drain_invoke(child->bs, begin);

            bdrv_drain_invoke(child->bs, begin, true);

        }

    }

}
@@ -265,7 +267,7 @@ void bdrv_drained_begin(BlockDriverState *bs) 
        bdrv_parent_drained_begin(bs);

    }



    bdrv_drain_invoke(bs, true);

    bdrv_drain_invoke(bs, true, false);

    bdrv_drain_recurse(bs);

}
@@ -281,7 +283,7 @@ void bdrv_drained_end(BlockDriverState *bs) 
    }



    /* Re-enable things in child-to-parent order */

    bdrv_drain_invoke(bs, false);

    bdrv_drain_invoke(bs, false, false);

    bdrv_parent_drained_end(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_disable_external(aio_context);

        bdrv_parent_drained_begin(bs);

        bdrv_drain_invoke(bs, true);

        bdrv_drain_invoke(bs, true, true);

        aio_context_release(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 */

        aio_context_acquire(aio_context);

        bdrv_drain_invoke(bs, false);

        bdrv_drain_invoke(bs, false, true);

        bdrv_parent_drained_end(bs);

        aio_enable_external(aio_context);

        aio_context_release(aio_context);