diff options
| -rw-r--r-- | block.c | 25 | ||||
| -rw-r--r-- | block/io.c | 30 | ||||
| -rw-r--r-- | include/block/block_int-common.h | 8 | ||||
| -rw-r--r-- | tests/unit/test-bdrv-drain.c | 16 |
4 files changed, 39 insertions, 40 deletions
diff --git a/block.c b/block.c index 7ea0b82049..b8bab06e55 100644 --- a/block.c +++ b/block.c @@ -2855,7 +2855,6 @@ static void bdrv_replace_child_noperm(BdrvChild *child, { BlockDriverState *old_bs = child->bs; int new_bs_quiesce_counter; - int drain_saldo; assert(!child->frozen); assert(old_bs != new_bs); @@ -2865,16 +2864,13 @@ static void bdrv_replace_child_noperm(BdrvChild *child, assert(bdrv_get_aio_context(old_bs) == bdrv_get_aio_context(new_bs)); } - new_bs_quiesce_counter = (new_bs ? new_bs->quiesce_counter : 0); - drain_saldo = new_bs_quiesce_counter - child->parent_quiesce_counter; - /* * If the new child node is drained but the old one was not, flush * all outstanding requests to the old child node. */ - while (drain_saldo > 0 && child->klass->drained_begin) { + new_bs_quiesce_counter = (new_bs ? new_bs->quiesce_counter : 0); + if (new_bs_quiesce_counter && !child->quiesced_parent) { bdrv_parent_drained_begin_single(child, true); - drain_saldo--; } if (old_bs) { @@ -2890,16 +2886,6 @@ static void bdrv_replace_child_noperm(BdrvChild *child, if (new_bs) { assert_bdrv_graph_writable(new_bs); QLIST_INSERT_HEAD(&new_bs->parents, child, next_parent); - - /* - * Polling in bdrv_parent_drained_begin_single() may have led to the new - * node's quiesce_counter having been decreased. Not a problem, we just - * need to recognize this here and then invoke drained_end appropriately - * more often. - */ - assert(new_bs->quiesce_counter <= new_bs_quiesce_counter); - drain_saldo += new_bs->quiesce_counter - new_bs_quiesce_counter; - if (child->klass->attach) { child->klass->attach(child); } @@ -2908,10 +2894,13 @@ static void bdrv_replace_child_noperm(BdrvChild *child, /* * If the old child node was drained but the new one is not, allow * requests to come in only after the new node has been attached. + * + * Update new_bs_quiesce_counter because bdrv_parent_drained_begin_single() + * polls, which could have changed the value. */ - while (drain_saldo < 0 && child->klass->drained_end) { + new_bs_quiesce_counter = (new_bs ? new_bs->quiesce_counter : 0); + if (!new_bs_quiesce_counter && child->quiesced_parent) { bdrv_parent_drained_end_single(child); - drain_saldo++; } } diff --git a/block/io.c b/block/io.c index 75224480d0..87d6f22ec4 100644 --- a/block/io.c +++ b/block/io.c @@ -62,8 +62,9 @@ void bdrv_parent_drained_end_single(BdrvChild *c) { IO_OR_GS_CODE(); - assert(c->parent_quiesce_counter > 0); - c->parent_quiesce_counter--; + assert(c->quiesced_parent); + c->quiesced_parent = false; + if (c->klass->drained_end) { c->klass->drained_end(c); } @@ -110,7 +111,10 @@ void bdrv_parent_drained_begin_single(BdrvChild *c, bool poll) { AioContext *ctx = bdrv_child_get_parent_aio_context(c); IO_OR_GS_CODE(); - c->parent_quiesce_counter++; + + assert(!c->quiesced_parent); + c->quiesced_parent = true; + if (c->klass->drained_begin) { c->klass->drained_begin(c); } @@ -358,11 +362,12 @@ void bdrv_do_drained_begin_quiesce(BlockDriverState *bs, /* Stop things in parent-to-child order */ if (qatomic_fetch_inc(&bs->quiesce_counter) == 0) { aio_disable_external(bdrv_get_aio_context(bs)); - } - bdrv_parent_drained_begin(bs, parent, ignore_bds_parents); - if (bs->drv && bs->drv->bdrv_drain_begin) { - bs->drv->bdrv_drain_begin(bs); + /* TODO Remove ignore_bds_parents, we don't consider it any more */ + bdrv_parent_drained_begin(bs, parent, false); + if (bs->drv && bs->drv->bdrv_drain_begin) { + bs->drv->bdrv_drain_begin(bs); + } } } @@ -413,13 +418,14 @@ static void bdrv_do_drained_end(BlockDriverState *bs, BdrvChild *parent, assert(bs->quiesce_counter > 0); /* Re-enable things in child-to-parent order */ - if (bs->drv && bs->drv->bdrv_drain_end) { - bs->drv->bdrv_drain_end(bs); - } - bdrv_parent_drained_end(bs, parent, ignore_bds_parents); - old_quiesce_counter = qatomic_fetch_dec(&bs->quiesce_counter); if (old_quiesce_counter == 1) { + if (bs->drv && bs->drv->bdrv_drain_end) { + bs->drv->bdrv_drain_end(bs); + } + /* TODO Remove ignore_bds_parents, we don't consider it any more */ + bdrv_parent_drained_end(bs, parent, false); + aio_enable_external(bdrv_get_aio_context(bs)); } } diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h index 791dddfd7d..a6bc6b7fe9 100644 --- a/include/block/block_int-common.h +++ b/include/block/block_int-common.h @@ -980,13 +980,13 @@ struct BdrvChild { bool frozen; /* - * How many times the parent of this child has been drained + * True if the parent of this child has been drained by this BdrvChild * (through klass->drained_*). - * Usually, this is equal to bs->quiesce_counter (potentially - * reduced by bdrv_drain_all_count). It may differ while the + * + * It is generally true if bs->quiesce_counter > 0. It may differ while the * child is entering or leaving a drained section. */ - int parent_quiesce_counter; + bool quiesced_parent; QLIST_ENTRY(BdrvChild) next; QLIST_ENTRY(BdrvChild) next_parent; diff --git a/tests/unit/test-bdrv-drain.c b/tests/unit/test-bdrv-drain.c index dda08de8db..172bc6debc 100644 --- a/tests/unit/test-bdrv-drain.c +++ b/tests/unit/test-bdrv-drain.c @@ -296,7 +296,11 @@ static void test_quiesce_common(enum drain_type drain_type, bool recursive) do_drain_begin(drain_type, bs); - g_assert_cmpint(bs->quiesce_counter, ==, 1); + if (drain_type == BDRV_DRAIN_ALL) { + g_assert_cmpint(bs->quiesce_counter, ==, 2); + } else { + g_assert_cmpint(bs->quiesce_counter, ==, 1); + } g_assert_cmpint(backing->quiesce_counter, ==, !!recursive); do_drain_end(drain_type, bs); @@ -348,8 +352,8 @@ static void test_nested(void) for (outer = 0; outer < DRAIN_TYPE_MAX; outer++) { for (inner = 0; inner < DRAIN_TYPE_MAX; inner++) { - int backing_quiesce = (outer != BDRV_DRAIN) + - (inner != BDRV_DRAIN); + int backing_quiesce = (outer == BDRV_DRAIN_ALL) + + (inner == BDRV_DRAIN_ALL); g_assert_cmpint(bs->quiesce_counter, ==, 0); g_assert_cmpint(backing->quiesce_counter, ==, 0); @@ -359,10 +363,10 @@ static void test_nested(void) do_drain_begin(outer, bs); do_drain_begin(inner, bs); - g_assert_cmpint(bs->quiesce_counter, ==, 2); + g_assert_cmpint(bs->quiesce_counter, ==, 2 + !!backing_quiesce); g_assert_cmpint(backing->quiesce_counter, ==, backing_quiesce); - g_assert_cmpint(s->drain_count, ==, 2); - g_assert_cmpint(backing_s->drain_count, ==, backing_quiesce); + g_assert_cmpint(s->drain_count, ==, 1); + g_assert_cmpint(backing_s->drain_count, ==, !!backing_quiesce); do_drain_end(inner, bs); do_drain_end(outer, bs); |