From 0e894c93cae97bb792dc483be8e295d097ebd7a1 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Fri, 18 Nov 2022 18:40:58 +0100 Subject: [PATCH 16/31] block: Revert .bdrv_drained_begin/end to non-coroutine_fn RH-Author: Stefano Garzarella RH-MergeRequest: 135: block: Simplify drain to prevent QEMU from crashing during snapshot RH-Bugzilla: 2155112 RH-Acked-by: Emanuele Giuseppe Esposito RH-Acked-by: Hanna Czenczek RH-Acked-by: Kevin Wolf RH-Commit: [4/16] 86d6049e40a99604e414c2572b67f74b85868832 (sgarzarella/qemu-kvm-c-9-s) Polling during bdrv_drained_end() can be problematic (and in the future, we may get cases for bdrv_drained_begin() where polling is forbidden, and we don't care about already in-flight requests, but just want to prevent new requests from arriving). The .bdrv_drained_begin/end callbacks running in a coroutine is the only reason why we have to do this polling, so make them non-coroutine callbacks again. None of the callers actually yield any more. This means that bdrv_drained_end() effectively doesn't poll any more, even if AIO_WAIT_WHILE() loops are still there (their condition is false from the beginning). This is generally not a problem, but in test-bdrv-drain, some additional explicit aio_poll() calls need to be added because the test case wants to verify the final state after BHs have executed. Signed-off-by: Kevin Wolf Reviewed-by: Vladimir Sementsov-Ogievskiy Reviewed-by: Emanuele Giuseppe Esposito Reviewed-by: Hanna Reitz Message-Id: <20221118174110.55183-4-kwolf@redhat.com> Signed-off-by: Kevin Wolf (cherry picked from commit 5e8ac21717373cbe96ef7a91e216bf5788815d63) Signed-off-by: Stefano Garzarella --- block.c | 4 +-- block/io.c | 49 +++++--------------------------- block/qed.c | 6 ++-- block/throttle.c | 8 +++--- include/block/block_int-common.h | 10 ++++--- tests/unit/test-bdrv-drain.c | 18 ++++++------ 6 files changed, 32 insertions(+), 63 deletions(-) diff --git a/block.c b/block.c index ec184150a2..16a62a329c 100644 --- a/block.c +++ b/block.c @@ -1713,8 +1713,8 @@ static int bdrv_open_driver(BlockDriverState *bs, BlockDriver *drv, assert(is_power_of_2(bs->bl.request_alignment)); for (i = 0; i < bs->quiesce_counter; i++) { - if (drv->bdrv_co_drain_begin) { - drv->bdrv_co_drain_begin(bs); + if (drv->bdrv_drain_begin) { + drv->bdrv_drain_begin(bs); } } diff --git a/block/io.c b/block/io.c index b9424024f9..c2ed4b2af9 100644 --- a/block/io.c +++ b/block/io.c @@ -252,55 +252,20 @@ typedef struct { int *drained_end_counter; } BdrvCoDrainData; -static void coroutine_fn bdrv_drain_invoke_entry(void *opaque) -{ - BdrvCoDrainData *data = opaque; - BlockDriverState *bs = data->bs; - - if (data->begin) { - bs->drv->bdrv_co_drain_begin(bs); - } else { - bs->drv->bdrv_co_drain_end(bs); - } - - /* Set data->done and decrement drained_end_counter before bdrv_wakeup() */ - qatomic_mb_set(&data->done, true); - if (!data->begin) { - qatomic_dec(data->drained_end_counter); - } - bdrv_dec_in_flight(bs); - - g_free(data); -} - -/* Recursively call BlockDriver.bdrv_co_drain_begin/end callbacks */ +/* Recursively call BlockDriver.bdrv_drain_begin/end callbacks */ static void bdrv_drain_invoke(BlockDriverState *bs, bool begin, int *drained_end_counter) { - BdrvCoDrainData *data; - - if (!bs->drv || (begin && !bs->drv->bdrv_co_drain_begin) || - (!begin && !bs->drv->bdrv_co_drain_end)) { + if (!bs->drv || (begin && !bs->drv->bdrv_drain_begin) || + (!begin && !bs->drv->bdrv_drain_end)) { return; } - data = g_new(BdrvCoDrainData, 1); - *data = (BdrvCoDrainData) { - .bs = bs, - .done = false, - .begin = begin, - .drained_end_counter = drained_end_counter, - }; - - if (!begin) { - qatomic_inc(drained_end_counter); + if (begin) { + bs->drv->bdrv_drain_begin(bs); + } else { + bs->drv->bdrv_drain_end(bs); } - - /* Make sure the driver callback completes during the polling phase for - * drain_begin. */ - bdrv_inc_in_flight(bs); - data->co = qemu_coroutine_create(bdrv_drain_invoke_entry, data); - aio_co_schedule(bdrv_get_aio_context(bs), data->co); } /* Returns true if BDRV_POLL_WHILE() should go into a blocking aio_poll() */ diff --git a/block/qed.c b/block/qed.c index 013f826c44..c2691a85b1 100644 --- a/block/qed.c +++ b/block/qed.c @@ -262,7 +262,7 @@ static bool coroutine_fn qed_plug_allocating_write_reqs(BDRVQEDState *s) assert(!s->allocating_write_reqs_plugged); if (s->allocating_acb != NULL) { /* Another allocating write came concurrently. This cannot happen - * from bdrv_qed_co_drain_begin, but it can happen when the timer runs. + * from bdrv_qed_drain_begin, but it can happen when the timer runs. */ qemu_co_mutex_unlock(&s->table_lock); return false; @@ -365,7 +365,7 @@ static void bdrv_qed_attach_aio_context(BlockDriverState *bs, } } -static void coroutine_fn bdrv_qed_co_drain_begin(BlockDriverState *bs) +static void bdrv_qed_drain_begin(BlockDriverState *bs) { BDRVQEDState *s = bs->opaque; @@ -1661,7 +1661,7 @@ static BlockDriver bdrv_qed = { .bdrv_co_check = bdrv_qed_co_check, .bdrv_detach_aio_context = bdrv_qed_detach_aio_context, .bdrv_attach_aio_context = bdrv_qed_attach_aio_context, - .bdrv_co_drain_begin = bdrv_qed_co_drain_begin, + .bdrv_drain_begin = bdrv_qed_drain_begin, }; static void bdrv_qed_init(void) diff --git a/block/throttle.c b/block/throttle.c index 131eba3ab4..88851c84f4 100644 --- a/block/throttle.c +++ b/block/throttle.c @@ -214,7 +214,7 @@ static void throttle_reopen_abort(BDRVReopenState *reopen_state) reopen_state->opaque = NULL; } -static void coroutine_fn throttle_co_drain_begin(BlockDriverState *bs) +static void throttle_drain_begin(BlockDriverState *bs) { ThrottleGroupMember *tgm = bs->opaque; if (qatomic_fetch_inc(&tgm->io_limits_disabled) == 0) { @@ -222,7 +222,7 @@ static void coroutine_fn throttle_co_drain_begin(BlockDriverState *bs) } } -static void coroutine_fn throttle_co_drain_end(BlockDriverState *bs) +static void throttle_drain_end(BlockDriverState *bs) { ThrottleGroupMember *tgm = bs->opaque; assert(tgm->io_limits_disabled); @@ -261,8 +261,8 @@ static BlockDriver bdrv_throttle = { .bdrv_reopen_commit = throttle_reopen_commit, .bdrv_reopen_abort = throttle_reopen_abort, - .bdrv_co_drain_begin = throttle_co_drain_begin, - .bdrv_co_drain_end = throttle_co_drain_end, + .bdrv_drain_begin = throttle_drain_begin, + .bdrv_drain_end = throttle_drain_end, .is_filter = true, .strong_runtime_opts = throttle_strong_runtime_opts, diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h index 31ae91e56e..40d646d1ed 100644 --- a/include/block/block_int-common.h +++ b/include/block/block_int-common.h @@ -735,17 +735,19 @@ struct BlockDriver { void (*bdrv_io_unplug)(BlockDriverState *bs); /** - * bdrv_co_drain_begin is called if implemented in the beginning of a + * bdrv_drain_begin is called if implemented in the beginning of a * drain operation to drain and stop any internal sources of requests in * the driver. - * bdrv_co_drain_end is called if implemented at the end of the drain. + * bdrv_drain_end is called if implemented at the end of the drain. * * They should be used by the driver to e.g. manage scheduled I/O * requests, or toggle an internal state. After the end of the drain new * requests will continue normally. + * + * Implementations of both functions must not call aio_poll(). */ - void coroutine_fn (*bdrv_co_drain_begin)(BlockDriverState *bs); - void coroutine_fn (*bdrv_co_drain_end)(BlockDriverState *bs); + void (*bdrv_drain_begin)(BlockDriverState *bs); + void (*bdrv_drain_end)(BlockDriverState *bs); bool (*bdrv_supports_persistent_dirty_bitmap)(BlockDriverState *bs); bool coroutine_fn (*bdrv_co_can_store_new_dirty_bitmap)( diff --git a/tests/unit/test-bdrv-drain.c b/tests/unit/test-bdrv-drain.c index 24f34e24ad..695519ee02 100644 --- a/tests/unit/test-bdrv-drain.c +++ b/tests/unit/test-bdrv-drain.c @@ -46,7 +46,7 @@ static void coroutine_fn sleep_in_drain_begin(void *opaque) bdrv_dec_in_flight(bs); } -static void coroutine_fn bdrv_test_co_drain_begin(BlockDriverState *bs) +static void bdrv_test_drain_begin(BlockDriverState *bs) { BDRVTestState *s = bs->opaque; s->drain_count++; @@ -57,7 +57,7 @@ static void coroutine_fn bdrv_test_co_drain_begin(BlockDriverState *bs) } } -static void coroutine_fn bdrv_test_co_drain_end(BlockDriverState *bs) +static void bdrv_test_drain_end(BlockDriverState *bs) { BDRVTestState *s = bs->opaque; s->drain_count--; @@ -111,8 +111,8 @@ static BlockDriver bdrv_test = { .bdrv_close = bdrv_test_close, .bdrv_co_preadv = bdrv_test_co_preadv, - .bdrv_co_drain_begin = bdrv_test_co_drain_begin, - .bdrv_co_drain_end = bdrv_test_co_drain_end, + .bdrv_drain_begin = bdrv_test_drain_begin, + .bdrv_drain_end = bdrv_test_drain_end, .bdrv_child_perm = bdrv_default_perms, @@ -1703,6 +1703,7 @@ static void test_blockjob_commit_by_drained_end(void) bdrv_drained_begin(bs_child); g_assert(!job_has_completed); bdrv_drained_end(bs_child); + aio_poll(qemu_get_aio_context(), false); g_assert(job_has_completed); bdrv_unref(bs_parents[0]); @@ -1858,6 +1859,7 @@ static void test_drop_intermediate_poll(void) g_assert(!job_has_completed); ret = bdrv_drop_intermediate(chain[1], chain[0], NULL); + aio_poll(qemu_get_aio_context(), false); g_assert(ret == 0); g_assert(job_has_completed); @@ -1946,7 +1948,7 @@ static void coroutine_fn bdrv_replace_test_drain_co(void *opaque) * .was_drained. * Increment .drain_count. */ -static void coroutine_fn bdrv_replace_test_co_drain_begin(BlockDriverState *bs) +static void bdrv_replace_test_drain_begin(BlockDriverState *bs) { BDRVReplaceTestState *s = bs->opaque; @@ -1977,7 +1979,7 @@ static void coroutine_fn bdrv_replace_test_read_entry(void *opaque) * If .drain_count reaches 0 and the node has a backing file, issue a * read request. */ -static void coroutine_fn bdrv_replace_test_co_drain_end(BlockDriverState *bs) +static void bdrv_replace_test_drain_end(BlockDriverState *bs) { BDRVReplaceTestState *s = bs->opaque; @@ -2002,8 +2004,8 @@ static BlockDriver bdrv_replace_test = { .bdrv_close = bdrv_replace_test_close, .bdrv_co_preadv = bdrv_replace_test_co_preadv, - .bdrv_co_drain_begin = bdrv_replace_test_co_drain_begin, - .bdrv_co_drain_end = bdrv_replace_test_co_drain_end, + .bdrv_drain_begin = bdrv_replace_test_drain_begin, + .bdrv_drain_end = bdrv_replace_test_drain_end, .bdrv_child_perm = bdrv_default_perms, }; -- 2.31.1