| Message ID | 20170921131707.17364-2-el13635@mail.ntua.gr (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, 09/21 16:17, Manos Pitsidianakis wrote: > BlockDriverState has a bdrv_do_drain() callback but no equivalent for the end s/bdrv_do_drain/bdrv_co_drain/ > of the drain. The throttle driver (block/throttle.c) needs a way to mark the > end of the drain in order to toggle io_limits_disabled correctly, thus > bdrv_co_drain_end is needed. > > Signed-off-by: Manos Pitsidianakis <el13635@mail.ntua.gr> > --- > include/block/block_int.h | 6 ++++++ > block/io.c | 48 +++++++++++++++++++++++++++++++++-------------- > 2 files changed, 40 insertions(+), 14 deletions(-) > > diff --git a/include/block/block_int.h b/include/block/block_int.h > index ba4c383393..21950cfda3 100644 > --- a/include/block/block_int.h > +++ b/include/block/block_int.h > @@ -356,8 +356,14 @@ struct BlockDriver { > /** > * Drain and stop any internal sources of requests in the driver, and > * remain so until next I/O callback (e.g. bdrv_co_writev) is called. This line needs update too, maybe: /** * bdrv_co_drain drains and stops any ... and remain so until * bdrv_co_drain_end is called. > + * > + * The callbacks are called at the beginning and ending of the drain > + * respectively. They should be implemented if the driver needs to e.g. As implied by above change, should we explicitly require "should both be implemented"? It may not be technically required, but I think is cleaner and easier to reason about. > + * manage scheduled I/O requests, or toggle an internal state. After an s/After an/After a/ > + * bdrv_co_drain_end() invocation new requests will continue normally. > */ > void coroutine_fn (*bdrv_co_drain)(BlockDriverState *bs); > + void coroutine_fn (*bdrv_co_drain_end)(BlockDriverState *bs); > > void (*bdrv_add_child)(BlockDriverState *parent, BlockDriverState *child, > Error **errp); > diff --git a/block/io.c b/block/io.c > index 4378ae4c7d..b0a10ad3ef 100644 > --- a/block/io.c > +++ b/block/io.c > @@ -153,6 +153,7 @@ typedef struct { > Coroutine *co; > BlockDriverState *bs; > bool done; > + bool begin; > } BdrvCoDrainData; > > static void coroutine_fn bdrv_drain_invoke_entry(void *opaque) > @@ -160,18 +161,23 @@ static void coroutine_fn bdrv_drain_invoke_entry(void *opaque) > BdrvCoDrainData *data = opaque; > BlockDriverState *bs = data->bs; > > - bs->drv->bdrv_co_drain(bs); > + if (data->begin) { > + bs->drv->bdrv_co_drain(bs); > + } else { > + bs->drv->bdrv_co_drain_end(bs); > + } > > /* Set data->done before reading bs->wakeup. */ > atomic_mb_set(&data->done, true); > bdrv_wakeup(bs); > } > > -static void bdrv_drain_invoke(BlockDriverState *bs) > +static void bdrv_drain_invoke(BlockDriverState *bs, bool begin) > { > - BdrvCoDrainData data = { .bs = bs, .done = false }; > + BdrvCoDrainData data = { .bs = bs, .done = false, .begin = begin}; > > - if (!bs->drv || !bs->drv->bdrv_co_drain) { > + if (!bs->drv || (begin && !bs->drv->bdrv_co_drain) || > + (!begin && !bs->drv->bdrv_co_drain_end)) { > return; > } > > @@ -180,15 +186,16 @@ static void bdrv_drain_invoke(BlockDriverState *bs) > BDRV_POLL_WHILE(bs, !data.done); > } > > -static bool bdrv_drain_recurse(BlockDriverState *bs) > +static bool bdrv_drain_recurse(BlockDriverState *bs, bool begin) > { > BdrvChild *child, *tmp; > bool waited; > > - waited = BDRV_POLL_WHILE(bs, atomic_read(&bs->in_flight) > 0); > - > /* Ensure any pending metadata writes are submitted to bs->file. */ > - bdrv_drain_invoke(bs); > + bdrv_drain_invoke(bs, begin); > + > + /* Wait for drained requests to finish */ > + waited = BDRV_POLL_WHILE(bs, atomic_read(&bs->in_flight) > 0); > > QLIST_FOREACH_SAFE(child, &bs->children, next, tmp) { > BlockDriverState *bs = child->bs; > @@ -205,7 +212,7 @@ static bool bdrv_drain_recurse(BlockDriverState *bs) > */ > bdrv_ref(bs); > } > - waited |= bdrv_drain_recurse(bs); > + waited |= bdrv_drain_recurse(bs, begin); > if (in_main_loop) { > bdrv_unref(bs); > } > @@ -221,12 +228,18 @@ static void bdrv_co_drain_bh_cb(void *opaque) > BlockDriverState *bs = data->bs; > > bdrv_dec_in_flight(bs); > - bdrv_drained_begin(bs); > + if (data->begin) { > + bdrv_drained_begin(bs); > + } else { > + bdrv_drained_end(bs); > + } > + > data->done = true; > aio_co_wake(co); > } > > -static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs) > +static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs, > + bool begin) > { > BdrvCoDrainData data; > > @@ -239,6 +252,7 @@ static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs) > .co = qemu_coroutine_self(), > .bs = bs, > .done = false, > + .begin = begin, > }; > bdrv_inc_in_flight(bs); > aio_bh_schedule_oneshot(bdrv_get_aio_context(bs), > @@ -253,7 +267,7 @@ static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs) > void bdrv_drained_begin(BlockDriverState *bs) > { > if (qemu_in_coroutine()) { > - bdrv_co_yield_to_drain(bs); > + bdrv_co_yield_to_drain(bs, true); > return; > } > > @@ -262,17 +276,22 @@ void bdrv_drained_begin(BlockDriverState *bs) > bdrv_parent_drained_begin(bs); > } > > - bdrv_drain_recurse(bs); > + bdrv_drain_recurse(bs, true); > } > > void bdrv_drained_end(BlockDriverState *bs) > { > + if (qemu_in_coroutine()) { > + bdrv_co_yield_to_drain(bs, false); > + return; > + } > assert(bs->quiesce_counter > 0); > if (atomic_fetch_dec(&bs->quiesce_counter) > 1) { > return; > } > > bdrv_parent_drained_end(bs); > + bdrv_drain_recurse(bs, false); > aio_enable_external(bdrv_get_aio_context(bs)); > } > > @@ -350,7 +369,7 @@ void bdrv_drain_all_begin(void) > aio_context_acquire(aio_context); > for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) { > if (aio_context == bdrv_get_aio_context(bs)) { > - waited |= bdrv_drain_recurse(bs); > + waited |= bdrv_drain_recurse(bs, true); > } > } > aio_context_release(aio_context); > @@ -371,6 +390,7 @@ void bdrv_drain_all_end(void) > aio_context_acquire(aio_context); > aio_enable_external(aio_context); > bdrv_parent_drained_end(bs); > + bdrv_drain_recurse(bs, false); > aio_context_release(aio_context); > } > > -- > 2.11.0 >
On Thu, 09/21 16:17, Manos Pitsidianakis wrote: > BlockDriverState has a bdrv_do_drain() callback but no equivalent for the end > of the drain. The throttle driver (block/throttle.c) needs a way to mark the > end of the drain in order to toggle io_limits_disabled correctly, thus > bdrv_co_drain_end is needed. > > Signed-off-by: Manos Pitsidianakis <el13635@mail.ntua.gr> Reviewed-by: Fam Zheng <famz@redhat.com>
On Thu, Sep 21, 2017 at 09:29:43PM +0800, Fam Zheng wrote: >On Thu, 09/21 16:17, Manos Pitsidianakis wrote: >> BlockDriverState has a bdrv_do_drain() callback but no equivalent for the end > >s/bdrv_do_drain/bdrv_co_drain/ > >> of the drain. The throttle driver (block/throttle.c) needs a way to mark the >> end of the drain in order to toggle io_limits_disabled correctly, thus >> bdrv_co_drain_end is needed. >> >> Signed-off-by: Manos Pitsidianakis <el13635@mail.ntua.gr> >> --- >> include/block/block_int.h | 6 ++++++ >> block/io.c | 48 +++++++++++++++++++++++++++++++++-------------- >> 2 files changed, 40 insertions(+), 14 deletions(-) >> >> diff --git a/include/block/block_int.h b/include/block/block_int.h >> index ba4c383393..21950cfda3 100644 >> --- a/include/block/block_int.h >> +++ b/include/block/block_int.h >> @@ -356,8 +356,14 @@ struct BlockDriver { >> /** >> * Drain and stop any internal sources of requests in the driver, and >> * remain so until next I/O callback (e.g. bdrv_co_writev) is called. > >This line needs update too, maybe: > > /** > * bdrv_co_drain drains and stops any ... and remain so until > * bdrv_co_drain_end is called. > >> + * >> + * The callbacks are called at the beginning and ending of the drain >> + * respectively. They should be implemented if the driver needs to e.g. > >As implied by above change, should we explicitly require "should both be >implemented"? It may not be technically required, but I think is cleaner and >easier to reason about. > It might imply to someone that there's an assert(drv->bdrv_co_drain_begin && drv->bdrv_co_drain_end) somewhere unless you state they don't have to be implemented at the same time. How about we be completely explicit: bdrv_co_drain_begin is called if implemented in the beggining 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. 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. I hope this is easier for a reader to understand! >> + * manage scheduled I/O requests, or toggle an internal state. >> After an > >s/After an/After a/ > >> + * bdrv_co_drain_end() invocation new requests will continue normally. >> */ >> void coroutine_fn (*bdrv_co_drain)(BlockDriverState *bs); >> + void coroutine_fn (*bdrv_co_drain_end)(BlockDriverState *bs); >> >> void (*bdrv_add_child)(BlockDriverState *parent, BlockDriverState *child, >> Error **errp); >> diff --git a/block/io.c b/block/io.c >> index 4378ae4c7d..b0a10ad3ef 100644 >> --- a/block/io.c >> +++ b/block/io.c >> @@ -153,6 +153,7 @@ typedef struct { >> Coroutine *co; >> BlockDriverState *bs; >> bool done; >> + bool begin; >> } BdrvCoDrainData; >> >> static void coroutine_fn bdrv_drain_invoke_entry(void *opaque) >> @@ -160,18 +161,23 @@ static void coroutine_fn bdrv_drain_invoke_entry(void *opaque) >> BdrvCoDrainData *data = opaque; >> BlockDriverState *bs = data->bs; >> >> - bs->drv->bdrv_co_drain(bs); >> + if (data->begin) { >> + bs->drv->bdrv_co_drain(bs); >> + } else { >> + bs->drv->bdrv_co_drain_end(bs); >> + } >> >> /* Set data->done before reading bs->wakeup. */ >> atomic_mb_set(&data->done, true); >> bdrv_wakeup(bs); >> } >> >> -static void bdrv_drain_invoke(BlockDriverState *bs) >> +static void bdrv_drain_invoke(BlockDriverState *bs, bool begin) >> { >> - BdrvCoDrainData data = { .bs = bs, .done = false }; >> + BdrvCoDrainData data = { .bs = bs, .done = false, .begin = begin}; >> >> - if (!bs->drv || !bs->drv->bdrv_co_drain) { >> + if (!bs->drv || (begin && !bs->drv->bdrv_co_drain) || >> + (!begin && !bs->drv->bdrv_co_drain_end)) { >> return; >> } >> >> @@ -180,15 +186,16 @@ static void bdrv_drain_invoke(BlockDriverState *bs) >> BDRV_POLL_WHILE(bs, !data.done); >> } >> >> -static bool bdrv_drain_recurse(BlockDriverState *bs) >> +static bool bdrv_drain_recurse(BlockDriverState *bs, bool begin) >> { >> BdrvChild *child, *tmp; >> bool waited; >> >> - waited = BDRV_POLL_WHILE(bs, atomic_read(&bs->in_flight) > 0); >> - >> /* Ensure any pending metadata writes are submitted to bs->file. */ >> - bdrv_drain_invoke(bs); >> + bdrv_drain_invoke(bs, begin); >> + >> + /* Wait for drained requests to finish */ >> + waited = BDRV_POLL_WHILE(bs, atomic_read(&bs->in_flight) > 0); >> >> QLIST_FOREACH_SAFE(child, &bs->children, next, tmp) { >> BlockDriverState *bs = child->bs; >> @@ -205,7 +212,7 @@ static bool bdrv_drain_recurse(BlockDriverState *bs) >> */ >> bdrv_ref(bs); >> } >> - waited |= bdrv_drain_recurse(bs); >> + waited |= bdrv_drain_recurse(bs, begin); >> if (in_main_loop) { >> bdrv_unref(bs); >> } >> @@ -221,12 +228,18 @@ static void bdrv_co_drain_bh_cb(void *opaque) >> BlockDriverState *bs = data->bs; >> >> bdrv_dec_in_flight(bs); >> - bdrv_drained_begin(bs); >> + if (data->begin) { >> + bdrv_drained_begin(bs); >> + } else { >> + bdrv_drained_end(bs); >> + } >> + >> data->done = true; >> aio_co_wake(co); >> } >> >> -static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs) >> +static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs, >> + bool begin) >> { >> BdrvCoDrainData data; >> >> @@ -239,6 +252,7 @@ static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs) >> .co = qemu_coroutine_self(), >> .bs = bs, >> .done = false, >> + .begin = begin, >> }; >> bdrv_inc_in_flight(bs); >> aio_bh_schedule_oneshot(bdrv_get_aio_context(bs), >> @@ -253,7 +267,7 @@ static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs) >> void bdrv_drained_begin(BlockDriverState *bs) >> { >> if (qemu_in_coroutine()) { >> - bdrv_co_yield_to_drain(bs); >> + bdrv_co_yield_to_drain(bs, true); >> return; >> } >> >> @@ -262,17 +276,22 @@ void bdrv_drained_begin(BlockDriverState *bs) >> bdrv_parent_drained_begin(bs); >> } >> >> - bdrv_drain_recurse(bs); >> + bdrv_drain_recurse(bs, true); >> } >> >> void bdrv_drained_end(BlockDriverState *bs) >> { >> + if (qemu_in_coroutine()) { >> + bdrv_co_yield_to_drain(bs, false); >> + return; >> + } >> assert(bs->quiesce_counter > 0); >> if (atomic_fetch_dec(&bs->quiesce_counter) > 1) { >> return; >> } >> >> bdrv_parent_drained_end(bs); >> + bdrv_drain_recurse(bs, false); >> aio_enable_external(bdrv_get_aio_context(bs)); >> } >> >> @@ -350,7 +369,7 @@ void bdrv_drain_all_begin(void) >> aio_context_acquire(aio_context); >> for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) { >> if (aio_context == bdrv_get_aio_context(bs)) { >> - waited |= bdrv_drain_recurse(bs); >> + waited |= bdrv_drain_recurse(bs, true); >> } >> } >> aio_context_release(aio_context); >> @@ -371,6 +390,7 @@ void bdrv_drain_all_end(void) >> aio_context_acquire(aio_context); >> aio_enable_external(aio_context); >> bdrv_parent_drained_end(bs); >> + bdrv_drain_recurse(bs, false); >> aio_context_release(aio_context); >> } >> >> -- >> 2.11.0 >> >
On Thu, 09/21 18:39, Manos Pitsidianakis wrote: > On Thu, Sep 21, 2017 at 09:29:43PM +0800, Fam Zheng wrote: > > On Thu, 09/21 16:17, Manos Pitsidianakis wrote: > > > BlockDriverState has a bdrv_do_drain() callback but no equivalent for the end > > > > s/bdrv_do_drain/bdrv_co_drain/ > > > > > of the drain. The throttle driver (block/throttle.c) needs a way to mark the > > > end of the drain in order to toggle io_limits_disabled correctly, thus > > > bdrv_co_drain_end is needed. > > > > > > Signed-off-by: Manos Pitsidianakis <el13635@mail.ntua.gr> > > > --- > > > include/block/block_int.h | 6 ++++++ > > > block/io.c | 48 +++++++++++++++++++++++++++++++++-------------- > > > 2 files changed, 40 insertions(+), 14 deletions(-) > > > > > > diff --git a/include/block/block_int.h b/include/block/block_int.h > > > index ba4c383393..21950cfda3 100644 > > > --- a/include/block/block_int.h > > > +++ b/include/block/block_int.h > > > @@ -356,8 +356,14 @@ struct BlockDriver { > > > /** > > > * Drain and stop any internal sources of requests in the driver, and > > > * remain so until next I/O callback (e.g. bdrv_co_writev) is called. > > > > This line needs update too, maybe: > > > > /** > > * bdrv_co_drain drains and stops any ... and remain so until > > * bdrv_co_drain_end is called. > > > > > + * > > > + * The callbacks are called at the beginning and ending of the drain > > > + * respectively. They should be implemented if the driver needs to e.g. > > > > As implied by above change, should we explicitly require "should both be > > implemented"? It may not be technically required, but I think is cleaner and > > easier to reason about. > > > > It might imply to someone that there's an assert(drv->bdrv_co_drain_begin && > drv->bdrv_co_drain_end) somewhere unless you state they don't have to be > implemented at the same time. How about we be completely explicit: > > bdrv_co_drain_begin is called if implemented in the beggining 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. > > 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. > > I hope this is easier for a reader to understand! I don't like the inconsistent semantics of when the drained section ends, if we allow drivers to implement bdrv_co_drain_begin but omit bdrv_co_drained_end. Currently the point where the section ends is, as said in the comment, when next I/O callback is invoked. Now we are adding the explicit ".bdrv_co_drain_end" into the fomular, if we still keep the previous convention, the interface contract is just mixed of two things for no good reason. I don't think it's technically necessary. Let's just add the assert: assert(!!drv->bdrv_co_drain_begin == !!bdrv_co_drain_end); in bdrv_drain_invoke, add a comment here, then add an empty .bdrv_co_drain_end in qed. Fam
Am 22.09.2017 um 04:30 hat Fam Zheng geschrieben: > On Thu, 09/21 18:39, Manos Pitsidianakis wrote: > > On Thu, Sep 21, 2017 at 09:29:43PM +0800, Fam Zheng wrote: > > > On Thu, 09/21 16:17, Manos Pitsidianakis wrote: > > It might imply to someone that there's an assert(drv->bdrv_co_drain_begin && > > drv->bdrv_co_drain_end) somewhere unless you state they don't have to be > > implemented at the same time. How about we be completely explicit: > > > > bdrv_co_drain_begin is called if implemented in the beggining 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. > > > > 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. > > > > I hope this is easier for a reader to understand! > > I don't like the inconsistent semantics of when the drained section > ends, if we allow drivers to implement bdrv_co_drain_begin but omit > bdrv_co_drained_end. Currently the point where the section ends is, > as said in the comment, when next I/O callback is invoked. Now we are > adding the explicit ".bdrv_co_drain_end" into the fomular, if we still > keep the previous convention, the interface contract is just mixed of > two things for no good reason. I don't think it's technically > necessary. We don't keep the convention with the next I/O callback. We just allow drivers to omit an empty implementation of either callback, which seems to be a very sensible default to me. > Let's just add the assert: > > assert(!!drv->bdrv_co_drain_begin == !!bdrv_co_drain_end); > > in bdrv_drain_invoke, add a comment here I'm not in favour of this, but if we do want to have it, wouldn't bdrv_register() be a much better place for the assertion? > then add an empty .bdrv_co_drain_end in qed. If you need empty functions anywhere, it's a sign that we have a bad default behaviour. Kevin
On Fri, 09/22 13:03, Kevin Wolf wrote: > Am 22.09.2017 um 04:30 hat Fam Zheng geschrieben: > > On Thu, 09/21 18:39, Manos Pitsidianakis wrote: > > > On Thu, Sep 21, 2017 at 09:29:43PM +0800, Fam Zheng wrote: > > > > On Thu, 09/21 16:17, Manos Pitsidianakis wrote: > > > It might imply to someone that there's an assert(drv->bdrv_co_drain_begin && > > > drv->bdrv_co_drain_end) somewhere unless you state they don't have to be > > > implemented at the same time. How about we be completely explicit: > > > > > > bdrv_co_drain_begin is called if implemented in the beggining 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. > > > > > > 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. > > > > > > I hope this is easier for a reader to understand! > > > > I don't like the inconsistent semantics of when the drained section > > ends, if we allow drivers to implement bdrv_co_drain_begin but omit > > bdrv_co_drained_end. Currently the point where the section ends is, > > as said in the comment, when next I/O callback is invoked. Now we are > > adding the explicit ".bdrv_co_drain_end" into the fomular, if we still > > keep the previous convention, the interface contract is just mixed of > > two things for no good reason. I don't think it's technically > > necessary. > > We don't keep the convention with the next I/O callback. We just allow > drivers to omit an empty implementation of either callback, which seems > to be a very sensible default to me. > OK, I'm fine with this. Fam
diff --git a/include/block/block_int.h b/include/block/block_int.h index ba4c383393..21950cfda3 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -356,8 +356,14 @@ struct BlockDriver { /** * Drain and stop any internal sources of requests in the driver, and * remain so until next I/O callback (e.g. bdrv_co_writev) is called. + * + * The callbacks are called at the beginning and ending of the drain + * respectively. They should be implemented if the driver needs to e.g. + * manage scheduled I/O requests, or toggle an internal state. After an + * bdrv_co_drain_end() invocation new requests will continue normally. */ void coroutine_fn (*bdrv_co_drain)(BlockDriverState *bs); + void coroutine_fn (*bdrv_co_drain_end)(BlockDriverState *bs); void (*bdrv_add_child)(BlockDriverState *parent, BlockDriverState *child, Error **errp); diff --git a/block/io.c b/block/io.c index 4378ae4c7d..b0a10ad3ef 100644 --- a/block/io.c +++ b/block/io.c @@ -153,6 +153,7 @@ typedef struct { Coroutine *co; BlockDriverState *bs; bool done; + bool begin; } BdrvCoDrainData; static void coroutine_fn bdrv_drain_invoke_entry(void *opaque) @@ -160,18 +161,23 @@ static void coroutine_fn bdrv_drain_invoke_entry(void *opaque) BdrvCoDrainData *data = opaque; BlockDriverState *bs = data->bs; - bs->drv->bdrv_co_drain(bs); + if (data->begin) { + bs->drv->bdrv_co_drain(bs); + } else { + bs->drv->bdrv_co_drain_end(bs); + } /* Set data->done before reading bs->wakeup. */ atomic_mb_set(&data->done, true); bdrv_wakeup(bs); } -static void bdrv_drain_invoke(BlockDriverState *bs) +static void bdrv_drain_invoke(BlockDriverState *bs, bool begin) { - BdrvCoDrainData data = { .bs = bs, .done = false }; + BdrvCoDrainData data = { .bs = bs, .done = false, .begin = begin}; - if (!bs->drv || !bs->drv->bdrv_co_drain) { + if (!bs->drv || (begin && !bs->drv->bdrv_co_drain) || + (!begin && !bs->drv->bdrv_co_drain_end)) { return; } @@ -180,15 +186,16 @@ static void bdrv_drain_invoke(BlockDriverState *bs) BDRV_POLL_WHILE(bs, !data.done); } -static bool bdrv_drain_recurse(BlockDriverState *bs) +static bool bdrv_drain_recurse(BlockDriverState *bs, bool begin) { BdrvChild *child, *tmp; bool waited; - waited = BDRV_POLL_WHILE(bs, atomic_read(&bs->in_flight) > 0); - /* Ensure any pending metadata writes are submitted to bs->file. */ - bdrv_drain_invoke(bs); + bdrv_drain_invoke(bs, begin); + + /* Wait for drained requests to finish */ + waited = BDRV_POLL_WHILE(bs, atomic_read(&bs->in_flight) > 0); QLIST_FOREACH_SAFE(child, &bs->children, next, tmp) { BlockDriverState *bs = child->bs; @@ -205,7 +212,7 @@ static bool bdrv_drain_recurse(BlockDriverState *bs) */ bdrv_ref(bs); } - waited |= bdrv_drain_recurse(bs); + waited |= bdrv_drain_recurse(bs, begin); if (in_main_loop) { bdrv_unref(bs); } @@ -221,12 +228,18 @@ static void bdrv_co_drain_bh_cb(void *opaque) BlockDriverState *bs = data->bs; bdrv_dec_in_flight(bs); - bdrv_drained_begin(bs); + if (data->begin) { + bdrv_drained_begin(bs); + } else { + bdrv_drained_end(bs); + } + data->done = true; aio_co_wake(co); } -static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs) +static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs, + bool begin) { BdrvCoDrainData data; @@ -239,6 +252,7 @@ static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs) .co = qemu_coroutine_self(), .bs = bs, .done = false, + .begin = begin, }; bdrv_inc_in_flight(bs); aio_bh_schedule_oneshot(bdrv_get_aio_context(bs), @@ -253,7 +267,7 @@ static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs) void bdrv_drained_begin(BlockDriverState *bs) { if (qemu_in_coroutine()) { - bdrv_co_yield_to_drain(bs); + bdrv_co_yield_to_drain(bs, true); return; } @@ -262,17 +276,22 @@ void bdrv_drained_begin(BlockDriverState *bs) bdrv_parent_drained_begin(bs); } - bdrv_drain_recurse(bs); + bdrv_drain_recurse(bs, true); } void bdrv_drained_end(BlockDriverState *bs) { + if (qemu_in_coroutine()) { + bdrv_co_yield_to_drain(bs, false); + return; + } assert(bs->quiesce_counter > 0); if (atomic_fetch_dec(&bs->quiesce_counter) > 1) { return; } bdrv_parent_drained_end(bs); + bdrv_drain_recurse(bs, false); aio_enable_external(bdrv_get_aio_context(bs)); } @@ -350,7 +369,7 @@ void bdrv_drain_all_begin(void) aio_context_acquire(aio_context); for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) { if (aio_context == bdrv_get_aio_context(bs)) { - waited |= bdrv_drain_recurse(bs); + waited |= bdrv_drain_recurse(bs, true); } } aio_context_release(aio_context); @@ -371,6 +390,7 @@ void bdrv_drain_all_end(void) aio_context_acquire(aio_context); aio_enable_external(aio_context); bdrv_parent_drained_end(bs); + bdrv_drain_recurse(bs, false); aio_context_release(aio_context); }
BlockDriverState has a bdrv_do_drain() callback but no equivalent for the end of the drain. The throttle driver (block/throttle.c) needs a way to mark the end of the drain in order to toggle io_limits_disabled correctly, thus bdrv_co_drain_end is needed. Signed-off-by: Manos Pitsidianakis <el13635@mail.ntua.gr> --- include/block/block_int.h | 6 ++++++ block/io.c | 48 +++++++++++++++++++++++++++++++++-------------- 2 files changed, 40 insertions(+), 14 deletions(-)