Commit 79ab8b21 authored by Kevin Wolf's avatar Kevin Wolf
Browse files

block: Use bdrv_do_drain_begin/end in bdrv_drain_all() 



bdrv_do_drain_begin/end() implement already everything that
bdrv_drain_all_begin/end() need and currently still do manually: Disable
external events, call parent drain callbacks, call block driver
callbacks.

It also does two more things:

The first is incrementing bs->quiesce_counter. bdrv_drain_all() already
stood out in the test case by behaving different from the other drain
variants. Adding this is not only safe, but in fact a bug fix.

The second is calling bdrv_drain_recurse(). We already do that later in
the same function in a loop, so basically doing an early first iteration
doesn't hurt.

Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
Reviewed-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent bb675689

block/io.c

+2 −8
Original line number Diff line number Diff line
@@ -413,11 +413,8 @@ 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);

        aio_disable_external(aio_context);

        bdrv_parent_drained_begin(bs, NULL);

        bdrv_drain_invoke(bs, true, true);

        bdrv_do_drained_begin(bs, true, NULL);

        aio_context_release(aio_context);



        if (!g_slist_find(aio_ctxs, aio_context)) {
@@ -458,11 +455,8 @@ 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);

        bdrv_drain_invoke(bs, false, true);

        bdrv_parent_drained_end(bs, NULL);

        aio_enable_external(aio_context);

        bdrv_do_drained_end(bs, true, NULL);

        aio_context_release(aio_context);

    }

}

tests/test-bdrv-drain.c

+4 −10
Original line number Diff line number Diff line
@@ -276,8 +276,7 @@ static void test_quiesce_common(enum drain_type drain_type, bool recursive) 


static void test_quiesce_drain_all(void)

{

    // XXX drain_all doesn't quiesce

    //test_quiesce_common(BDRV_DRAIN_ALL, true);

    test_quiesce_common(BDRV_DRAIN_ALL, true);

}



static void test_quiesce_drain(void)
@@ -319,12 +318,7 @@ static void test_nested(void) 


    for (outer = 0; outer < DRAIN_TYPE_MAX; outer++) {

        for (inner = 0; inner < DRAIN_TYPE_MAX; inner++) {

            /* XXX bdrv_drain_all() doesn't increase the quiesce_counter */

            int bs_quiesce      = (outer != BDRV_DRAIN_ALL) +

                                  (inner != BDRV_DRAIN_ALL);

            int backing_quiesce = (outer == BDRV_SUBTREE_DRAIN) +

                                  (inner == BDRV_SUBTREE_DRAIN);

            int backing_cb_cnt  = (outer != BDRV_DRAIN) +

            int backing_quiesce = (outer != BDRV_DRAIN) +

                                  (inner != BDRV_DRAIN);



            g_assert_cmpint(bs->quiesce_counter, ==, 0);
@@ -335,10 +329,10 @@ static void test_nested(void) 
            do_drain_begin(outer, bs);

            do_drain_begin(inner, bs);



            g_assert_cmpint(bs->quiesce_counter, ==, bs_quiesce);

            g_assert_cmpint(bs->quiesce_counter, ==, 2);

            g_assert_cmpint(backing->quiesce_counter, ==, backing_quiesce);

            g_assert_cmpint(s->drain_count, ==, 2);

            g_assert_cmpint(backing_s->drain_count, ==, backing_cb_cnt);

            g_assert_cmpint(backing_s->drain_count, ==, backing_quiesce);



            do_drain_end(inner, bs);

            do_drain_end(outer, bs);