From 8e1da77e6e4866876236d0f0c7b02dea87efd2a4 Mon Sep 17 00:00:00 2001 From: Max Reitz Date: Fri, 19 Jul 2019 11:26:11 +0200 Subject: [PATCH] block: Add @drained_end_counter Callers can now pass a pointer to an integer that bdrv_drain_invoke() (and its recursive callees) will increment for every bdrv_drain_invoke_entry() operation they schedule. bdrv_drain_invoke_entry() in turn will decrement it once it has invoked BlockDriver.bdrv_co_drain_end(). We use atomic operations to access the pointee, because the bdrv_do_drained_end() caller may wish to end drained sections for multiple nodes in different AioContexts (bdrv_drain_all_end() does, for example). This is the first step to moving the polling for BdrvCoDrainData.done to become true out of bdrv_drain_invoke() and into the root drained_end function. Signed-off-by: Max Reitz Signed-off-by: Kevin Wolf --- block/io.c | 58 ++++++++++++++++++++++++++++++++++++++++------------------ 1 file changed, 40 insertions(+), 18 deletions(-) diff --git a/block/io.c b/block/io.c index 1e618f9a37..c42e18b068 100644 --- a/block/io.c +++ b/block/io.c @@ -194,6 +194,7 @@ typedef struct { bool poll; BdrvChild *parent; bool ignore_bds_parents; + int *drained_end_counter; } BdrvCoDrainData; static void coroutine_fn bdrv_drain_invoke_entry(void *opaque) @@ -211,13 +212,18 @@ static void coroutine_fn bdrv_drain_invoke_entry(void *opaque) atomic_mb_set(&data->done, true); bdrv_dec_in_flight(bs); - if (data->begin) { + if (data->drained_end_counter) { + atomic_dec(data->drained_end_counter); + } + + if (data->begin || data->drained_end_counter) { g_free(data); } } /* 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, + int *drained_end_counter) { BdrvCoDrainData *data; @@ -230,16 +236,25 @@ static void bdrv_drain_invoke(BlockDriverState *bs, bool begin) *data = (BdrvCoDrainData) { .bs = bs, .done = false, - .begin = begin + .begin = begin, + .drained_end_counter = drained_end_counter, }; + if (!begin && drained_end_counter) { + atomic_inc(drained_end_counter); + } + /* 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); - if (!begin) { + /* + * TODO: Drop this and make callers pass @drained_end_counter and poll + * themselves + */ + if (!begin && !drained_end_counter) { BDRV_POLL_WHILE(bs, !data->done); g_free(data); } @@ -281,7 +296,8 @@ static void bdrv_do_drained_begin(BlockDriverState *bs, bool recursive, BdrvChild *parent, bool ignore_bds_parents, bool poll); static void bdrv_do_drained_end(BlockDriverState *bs, bool recursive, - BdrvChild *parent, bool ignore_bds_parents); + BdrvChild *parent, bool ignore_bds_parents, + int *drained_end_counter); static void bdrv_co_drain_bh_cb(void *opaque) { @@ -308,7 +324,8 @@ static void bdrv_co_drain_bh_cb(void *opaque) data->ignore_bds_parents, data->poll); } else { bdrv_do_drained_end(bs, data->recursive, data->parent, - data->ignore_bds_parents); + data->ignore_bds_parents, + data->drained_end_counter); } if (ctx == co_ctx) { aio_context_release(ctx); @@ -326,7 +343,8 @@ static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs, bool begin, bool recursive, BdrvChild *parent, bool ignore_bds_parents, - bool poll) + bool poll, + int *drained_end_counter) { BdrvCoDrainData data; @@ -343,7 +361,9 @@ static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs, .parent = parent, .ignore_bds_parents = ignore_bds_parents, .poll = poll, + .drained_end_counter = drained_end_counter, }; + if (bs) { bdrv_inc_in_flight(bs); } @@ -367,7 +387,7 @@ void bdrv_do_drained_begin_quiesce(BlockDriverState *bs, } bdrv_parent_drained_begin(bs, parent, ignore_bds_parents); - bdrv_drain_invoke(bs, true); + bdrv_drain_invoke(bs, true, NULL); } static void bdrv_do_drained_begin(BlockDriverState *bs, bool recursive, @@ -378,7 +398,7 @@ static void bdrv_do_drained_begin(BlockDriverState *bs, bool recursive, if (qemu_in_coroutine()) { bdrv_co_yield_to_drain(bs, true, recursive, parent, ignore_bds_parents, - poll); + poll, NULL); return; } @@ -419,20 +439,21 @@ void bdrv_subtree_drained_begin(BlockDriverState *bs) } static void bdrv_do_drained_end(BlockDriverState *bs, bool recursive, - BdrvChild *parent, bool ignore_bds_parents) + BdrvChild *parent, bool ignore_bds_parents, + int *drained_end_counter) { BdrvChild *child, *next; int old_quiesce_counter; if (qemu_in_coroutine()) { bdrv_co_yield_to_drain(bs, false, recursive, parent, ignore_bds_parents, - false); + false, drained_end_counter); return; } assert(bs->quiesce_counter > 0); /* Re-enable things in child-to-parent order */ - bdrv_drain_invoke(bs, false); + bdrv_drain_invoke(bs, false, drained_end_counter); bdrv_parent_drained_end(bs, parent, ignore_bds_parents); old_quiesce_counter = atomic_fetch_dec(&bs->quiesce_counter); @@ -444,19 +465,20 @@ static void bdrv_do_drained_end(BlockDriverState *bs, bool recursive, assert(!ignore_bds_parents); bs->recursive_quiesce_counter--; QLIST_FOREACH_SAFE(child, &bs->children, next, next) { - bdrv_do_drained_end(child->bs, true, child, ignore_bds_parents); + bdrv_do_drained_end(child->bs, true, child, ignore_bds_parents, + drained_end_counter); } } } void bdrv_drained_end(BlockDriverState *bs) { - bdrv_do_drained_end(bs, false, NULL, false); + bdrv_do_drained_end(bs, false, NULL, false, NULL); } void bdrv_subtree_drained_end(BlockDriverState *bs) { - bdrv_do_drained_end(bs, true, NULL, false); + bdrv_do_drained_end(bs, true, NULL, false, NULL); } void bdrv_apply_subtree_drain(BdrvChild *child, BlockDriverState *new_parent) @@ -473,7 +495,7 @@ void bdrv_unapply_subtree_drain(BdrvChild *child, BlockDriverState *old_parent) int i; for (i = 0; i < old_parent->recursive_quiesce_counter; i++) { - bdrv_do_drained_end(child->bs, true, child, false); + bdrv_do_drained_end(child->bs, true, child, false, NULL); } } @@ -543,7 +565,7 @@ void bdrv_drain_all_begin(void) BlockDriverState *bs = NULL; if (qemu_in_coroutine()) { - bdrv_co_yield_to_drain(NULL, true, false, NULL, true, true); + bdrv_co_yield_to_drain(NULL, true, false, NULL, true, true, NULL); return; } @@ -579,7 +601,7 @@ void bdrv_drain_all_end(void) AioContext *aio_context = bdrv_get_aio_context(bs); aio_context_acquire(aio_context); - bdrv_do_drained_end(bs, false, NULL, true); + bdrv_do_drained_end(bs, false, NULL, true, NULL); aio_context_release(aio_context); } -- 2.11.0