From ce0f141259f06fd77fde2519cc352618ad797ce2 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Thu, 7 Apr 2016 18:33:33 +0200 Subject: [PATCH] block: introduce bdrv_no_throttling_begin/end Extract the handling of throttling from bdrv_flush_io_queue. These new functions will soon become BdrvChildRole callbacks, as they can be generalized to "beginning of drain" and "end of drain". Reviewed-by: Alberto Garcia Signed-off-by: Paolo Bonzini Acked-by: Stefan Hajnoczi Signed-off-by: Kevin Wolf --- block.c | 1 - block/block-backend.c | 6 ++---- block/io.c | 33 +++++++++++++++++++++------------ block/throttle-groups.c | 4 ++++ include/block/block_int.h | 9 ++++++--- 5 files changed, 33 insertions(+), 20 deletions(-) diff --git a/block.c b/block.c index d4939b49bf..6cbad0e264 100644 --- a/block.c +++ b/block.c @@ -2261,7 +2261,6 @@ static void swap_feature_fields(BlockDriverState *bs_top, assert(!bs_new->throttle_state); if (bs_top->throttle_state) { - assert(bs_top->io_limits_enabled); bdrv_io_limits_enable(bs_new, throttle_group_get_name(bs_top)); bdrv_io_limits_disable(bs_top); } diff --git a/block/block-backend.c b/block/block-backend.c index 16c9d5e0f2..9538e79641 100644 --- a/block/block-backend.c +++ b/block/block-backend.c @@ -794,7 +794,6 @@ int blk_read_unthrottled(BlockBackend *blk, int64_t sector_num, uint8_t *buf, int nb_sectors) { BlockDriverState *bs = blk_bs(blk); - bool enabled; int ret; ret = blk_check_request(blk, sector_num, nb_sectors); @@ -802,10 +801,9 @@ int blk_read_unthrottled(BlockBackend *blk, int64_t sector_num, uint8_t *buf, return ret; } - enabled = bs->io_limits_enabled; - bs->io_limits_enabled = false; + bdrv_no_throttling_begin(bs); ret = blk_read(blk, sector_num, buf, nb_sectors); - bs->io_limits_enabled = enabled; + bdrv_no_throttling_end(bs); return ret; } diff --git a/block/io.c b/block/io.c index c4848563ad..b798040e52 100644 --- a/block/io.c +++ b/block/io.c @@ -65,28 +65,32 @@ void bdrv_set_io_limits(BlockDriverState *bs, throttle_group_config(bs, cfg); } -static void bdrv_start_throttled_reqs(BlockDriverState *bs) +void bdrv_no_throttling_begin(BlockDriverState *bs) { - bool enabled = bs->io_limits_enabled; + if (bs->io_limits_disabled++ == 0) { + throttle_group_restart_bs(bs); + } +} - bs->io_limits_enabled = false; - throttle_group_restart_bs(bs); - bs->io_limits_enabled = enabled; +void bdrv_no_throttling_end(BlockDriverState *bs) +{ + assert(bs->io_limits_disabled); + --bs->io_limits_disabled; } void bdrv_io_limits_disable(BlockDriverState *bs) { - bs->io_limits_enabled = false; - bdrv_start_throttled_reqs(bs); + assert(bs->throttle_state); + bdrv_no_throttling_begin(bs); throttle_group_unregister_bs(bs); + bdrv_no_throttling_end(bs); } /* should be called before bdrv_set_io_limits if a limit is set */ void bdrv_io_limits_enable(BlockDriverState *bs, const char *group) { - assert(!bs->io_limits_enabled); + assert(!bs->throttle_state); throttle_group_register_bs(bs, group); - bs->io_limits_enabled = true; } void bdrv_io_limits_update_group(BlockDriverState *bs, const char *group) @@ -302,18 +306,22 @@ static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs) */ void coroutine_fn bdrv_co_drain(BlockDriverState *bs) { + bdrv_no_throttling_begin(bs); bdrv_drain_recurse(bs); bdrv_co_yield_to_drain(bs); + bdrv_no_throttling_end(bs); } void bdrv_drain(BlockDriverState *bs) { + bdrv_no_throttling_begin(bs); bdrv_drain_recurse(bs); if (qemu_in_coroutine()) { bdrv_co_yield_to_drain(bs); } else { bdrv_drain_poll(bs); } + bdrv_no_throttling_end(bs); } /* @@ -336,6 +344,7 @@ void bdrv_drain_all(void) if (bs->job) { block_job_pause(bs->job); } + bdrv_no_throttling_begin(bs); bdrv_drain_recurse(bs); aio_context_release(aio_context); @@ -377,6 +386,7 @@ void bdrv_drain_all(void) AioContext *aio_context = bdrv_get_aio_context(bs); aio_context_acquire(aio_context); + bdrv_no_throttling_end(bs); if (bs->job) { block_job_resume(bs->job); } @@ -980,7 +990,7 @@ int coroutine_fn bdrv_co_do_preadv(BlockDriverState *bs, } /* throttling disk I/O */ - if (bs->io_limits_enabled) { + if (bs->throttle_state) { throttle_group_co_io_limits_intercept(bs, bytes, false); } @@ -1330,7 +1340,7 @@ int coroutine_fn bdrv_co_do_pwritev(BlockDriverState *bs, } /* throttling disk I/O */ - if (bs->io_limits_enabled) { + if (bs->throttle_state) { throttle_group_co_io_limits_intercept(bs, bytes, true); } @@ -2772,7 +2782,6 @@ void bdrv_flush_io_queue(BlockDriverState *bs) } else if (bs->file) { bdrv_flush_io_queue(bs->file->bs); } - bdrv_start_throttled_reqs(bs); } void bdrv_drained_begin(BlockDriverState *bs) diff --git a/block/throttle-groups.c b/block/throttle-groups.c index b796f6b9fa..9ac063a0cd 100644 --- a/block/throttle-groups.c +++ b/block/throttle-groups.c @@ -219,6 +219,10 @@ static bool throttle_group_schedule_timer(BlockDriverState *bs, ThrottleGroup *tg = container_of(ts, ThrottleGroup, ts); bool must_wait; + if (bs->io_limits_disabled) { + return false; + } + /* Check if any of the timers in this group is already armed */ if (tg->any_timer_armed[is_write]) { return true; diff --git a/include/block/block_int.h b/include/block/block_int.h index 10d87595be..ed9314b615 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -424,10 +424,10 @@ struct BlockDriverState { /* I/O throttling. * throttle_state tells us if this BDS has I/O limits configured. - * io_limits_enabled tells us if they are currently being - * enforced, but it can be temporarily set to false */ + * io_limits_disabled tells us if they are currently being enforced */ CoQueue throttled_reqs[2]; - bool io_limits_enabled; + unsigned int io_limits_disabled; + /* The following fields are protected by the ThrottleGroup lock. * See the ThrottleGroup documentation for details. */ ThrottleState *throttle_state; @@ -713,6 +713,9 @@ BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs, const BdrvChildRole *child_role); void bdrv_root_unref_child(BdrvChild *child); +void bdrv_no_throttling_begin(BlockDriverState *bs); +void bdrv_no_throttling_end(BlockDriverState *bs); + void blk_dev_change_media_cb(BlockBackend *blk, bool load); bool blk_dev_has_removable_media(BlockBackend *blk); bool blk_dev_has_tray(BlockBackend *blk);