| Message ID | 20200512144318.181049-2-kwolf@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | block: Synchronous bdrv_*() from coroutine in different AioContext | expand |
On 5/12/20 9:43 AM, Kevin Wolf wrote: > We have a few bdrv_*() functions that can either spawn a new coroutine > and wait for it with BDRV_POLL_WHILE() or use a fastpath if they are > alreeady running in a coroutine. All of them duplicate basically the already > same code. > > Factor the common code into a new function bdrv_run_co(). > > Signed-off-by: Kevin Wolf <kwolf@redhat.com> > --- > block/io.c | 104 +++++++++++++++-------------------------------------- > 1 file changed, 28 insertions(+), 76 deletions(-) > > diff --git a/block/io.c b/block/io.c > index 7d30e61edc..c1badaadc9 100644 > --- a/block/io.c > +++ b/block/io.c > @@ -891,6 +891,22 @@ static int bdrv_check_byte_request(BlockDriverState *bs, int64_t offset, > return 0; > } > > +static int bdrv_run_co(BlockDriverState *bs, CoroutineEntry *entry, > + void *opaque, int *ret) > +{ > + if (qemu_in_coroutine()) { > + /* Fast-path if already in coroutine context */ > + entry(opaque); > + } else { > + Coroutine *co = qemu_coroutine_create(entry, opaque); > + *ret = NOT_DONE; > + bdrv_coroutine_enter(bs, co); > + BDRV_POLL_WHILE(bs, *ret == NOT_DONE); For my reference, NOT_DONE is defined as INT_MAX, which does not seem to be used as a return value in other situations. > @@ -923,25 +939,15 @@ static int bdrv_prwv_co(BdrvChild *child, int64_t offset, > QEMUIOVector *qiov, bool is_write, > BdrvRequestFlags flags) > { > - Coroutine *co; > RwCo rwco = { > .child = child, > .offset = offset, > .qiov = qiov, > .is_write = is_write, > - .ret = NOT_DONE, > .flags = flags, > }; > > - if (qemu_in_coroutine()) { > - /* Fast-path if already in coroutine context */ > - bdrv_rw_co_entry(&rwco); > - } else { > - co = qemu_coroutine_create(bdrv_rw_co_entry, &rwco); > - bdrv_coroutine_enter(child->bs, co); > - BDRV_POLL_WHILE(child->bs, rwco.ret == NOT_DONE); > - } > - return rwco.ret; > + return bdrv_run_co(child->bs, bdrv_rw_co_entry, &rwco, &rwco.ret); So code that previously looped on NOT_DONE is obviously safe, while... > } > > int bdrv_pwrite_zeroes(BdrvChild *child, int64_t offset, > @@ -2230,7 +2236,6 @@ typedef struct BdrvCoBlockStatusData { > int64_t *map; > BlockDriverState **file; > int ret; > - bool done; > } BdrvCoBlockStatusData; > > int coroutine_fn bdrv_co_block_status_from_file(BlockDriverState *bs, > @@ -2492,7 +2497,6 @@ static void coroutine_fn bdrv_block_status_above_co_entry(void *opaque) > data->want_zero, > data->offset, data->bytes, > data->pnum, data->map, data->file); > - data->done = true; > aio_wait_kick(); ...code that looped on something else now has to be checked that data->ret is still being set to something useful. Fortunately that is true here. > @@ -2669,22 +2663,13 @@ static inline int > bdrv_rw_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos, > bool is_read) > { > - if (qemu_in_coroutine()) { > - return bdrv_co_rw_vmstate(bs, qiov, pos, is_read); > - } else { > - BdrvVmstateCo data = { > - .bs = bs, > - .qiov = qiov, > - .pos = pos, > - .is_read = is_read, > - .ret = -EINPROGRESS, > - }; > - Coroutine *co = qemu_coroutine_create(bdrv_co_rw_vmstate_entry, &data); > - > - bdrv_coroutine_enter(bs, co); > - BDRV_POLL_WHILE(bs, data.ret == -EINPROGRESS); > - return data.ret; It's a little harder to see whether -EINPROGRESS might ever be returned by a driver, but again this looks safe. Here, it's a little less obvious whether any driver might return -EINPROGRESS, but it looks like if they did that, Reviewed-by: Eric Blake <eblake@redhat.com> Conflicts with Vladimir's patches which try to add more coroutine wrappers (but those need a rebase anyway): https://lists.gnu.org/archive/html/qemu-devel/2020-04/msg04559.html
On 5/12/20 5:37 PM, Eric Blake wrote: > On 5/12/20 9:43 AM, Kevin Wolf wrote: >> We have a few bdrv_*() functions that can either spawn a new coroutine >> and wait for it with BDRV_POLL_WHILE() or use a fastpath if they are >> alreeady running in a coroutine. All of them duplicate basically the > > already > >> same code. >> >> Factor the common code into a new function bdrv_run_co(). >> >> Signed-off-by: Kevin Wolf <kwolf@redhat.com> >> --- >> block/io.c | 104 +++++++++++++++-------------------------------------- >> 1 file changed, 28 insertions(+), 76 deletions(-) >> >> diff --git a/block/io.c b/block/io.c >> index 7d30e61edc..c1badaadc9 100644 >> --- a/block/io.c >> +++ b/block/io.c >> @@ -891,6 +891,22 @@ static int >> bdrv_check_byte_request(BlockDriverState *bs, int64_t offset, >> return 0; >> } >> +static int bdrv_run_co(BlockDriverState *bs, CoroutineEntry *entry, >> + void *opaque, int *ret) >> +{ >> + if (qemu_in_coroutine()) { >> + /* Fast-path if already in coroutine context */ >> + entry(opaque); >> + } else { >> + Coroutine *co = qemu_coroutine_create(entry, opaque); >> + *ret = NOT_DONE; >> + bdrv_coroutine_enter(bs, co); >> + BDRV_POLL_WHILE(bs, *ret == NOT_DONE); > > For my reference, NOT_DONE is defined as INT_MAX, which does not seem to > be used as a return value in other situations. > >> @@ -923,25 +939,15 @@ static int bdrv_prwv_co(BdrvChild *child, >> int64_t offset, >> QEMUIOVector *qiov, bool is_write, >> BdrvRequestFlags flags) >> { >> - Coroutine *co; >> RwCo rwco = { >> .child = child, >> .offset = offset, >> .qiov = qiov, >> .is_write = is_write, >> - .ret = NOT_DONE, >> .flags = flags, >> }; >> - if (qemu_in_coroutine()) { >> - /* Fast-path if already in coroutine context */ >> - bdrv_rw_co_entry(&rwco); >> - } else { >> - co = qemu_coroutine_create(bdrv_rw_co_entry, &rwco); >> - bdrv_coroutine_enter(child->bs, co); >> - BDRV_POLL_WHILE(child->bs, rwco.ret == NOT_DONE); >> - } >> - return rwco.ret; >> + return bdrv_run_co(child->bs, bdrv_rw_co_entry, &rwco, &rwco.ret); > > So code that previously looped on NOT_DONE is obviously safe, while... > >> } >> int bdrv_pwrite_zeroes(BdrvChild *child, int64_t offset, >> @@ -2230,7 +2236,6 @@ typedef struct BdrvCoBlockStatusData { >> int64_t *map; >> BlockDriverState **file; >> int ret; >> - bool done; >> } BdrvCoBlockStatusData; >> int coroutine_fn bdrv_co_block_status_from_file(BlockDriverState *bs, >> @@ -2492,7 +2497,6 @@ static void coroutine_fn >> bdrv_block_status_above_co_entry(void *opaque) >> data->want_zero, >> data->offset, data->bytes, >> data->pnum, data->map, >> data->file); >> - data->done = true; >> aio_wait_kick(); > > ...code that looped on something else now has to be checked that > data->ret is still being set to something useful. Fortunately that is > true here. > >> @@ -2669,22 +2663,13 @@ static inline int >> bdrv_rw_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos, >> bool is_read) >> { >> - if (qemu_in_coroutine()) { >> - return bdrv_co_rw_vmstate(bs, qiov, pos, is_read); >> - } else { >> - BdrvVmstateCo data = { >> - .bs = bs, >> - .qiov = qiov, >> - .pos = pos, >> - .is_read = is_read, >> - .ret = -EINPROGRESS, >> - }; >> - Coroutine *co = >> qemu_coroutine_create(bdrv_co_rw_vmstate_entry, &data); >> - >> - bdrv_coroutine_enter(bs, co); >> - BDRV_POLL_WHILE(bs, data.ret == -EINPROGRESS); >> - return data.ret; > > It's a little harder to see whether -EINPROGRESS might ever be returned > by a driver, but again this looks safe. Maybe add a comment regarding -EINPROGRESS before calling bdrv_run_co() in bdrv_rw_vmstate()? Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> > > Here, it's a little less obvious whether any driver might return > -EINPROGRESS, but it looks like if they did that, > > Reviewed-by: Eric Blake <eblake@redhat.com> > > Conflicts with Vladimir's patches which try to add more coroutine > wrappers (but those need a rebase anyway): > https://lists.gnu.org/archive/html/qemu-devel/2020-04/msg04559.html >
20.05.2020 12:09, Philippe Mathieu-Daudé wrote: > On 5/12/20 5:37 PM, Eric Blake wrote: >> On 5/12/20 9:43 AM, Kevin Wolf wrote: >>> We have a few bdrv_*() functions that can either spawn a new coroutine >>> and wait for it with BDRV_POLL_WHILE() or use a fastpath if they are >>> alreeady running in a coroutine. All of them duplicate basically the >> >> already >> >>> same code. >>> >>> Factor the common code into a new function bdrv_run_co(). >>> >>> Signed-off-by: Kevin Wolf <kwolf@redhat.com> >>> --- >>> block/io.c | 104 +++++++++++++++-------------------------------------- >>> 1 file changed, 28 insertions(+), 76 deletions(-) >>> >>> diff --git a/block/io.c b/block/io.c >>> index 7d30e61edc..c1badaadc9 100644 >>> --- a/block/io.c >>> +++ b/block/io.c >>> @@ -891,6 +891,22 @@ static int bdrv_check_byte_request(BlockDriverState *bs, int64_t offset, >>> return 0; >>> } >>> +static int bdrv_run_co(BlockDriverState *bs, CoroutineEntry *entry, >>> + void *opaque, int *ret) >>> +{ >>> + if (qemu_in_coroutine()) { >>> + /* Fast-path if already in coroutine context */ >>> + entry(opaque); >>> + } else { >>> + Coroutine *co = qemu_coroutine_create(entry, opaque); >>> + *ret = NOT_DONE; >>> + bdrv_coroutine_enter(bs, co); >>> + BDRV_POLL_WHILE(bs, *ret == NOT_DONE); >> >> For my reference, NOT_DONE is defined as INT_MAX, which does not seem to be used as a return value in other situations. >> >>> @@ -923,25 +939,15 @@ static int bdrv_prwv_co(BdrvChild *child, int64_t offset, >>> QEMUIOVector *qiov, bool is_write, >>> BdrvRequestFlags flags) >>> { >>> - Coroutine *co; >>> RwCo rwco = { >>> .child = child, >>> .offset = offset, >>> .qiov = qiov, >>> .is_write = is_write, >>> - .ret = NOT_DONE, >>> .flags = flags, >>> }; >>> - if (qemu_in_coroutine()) { >>> - /* Fast-path if already in coroutine context */ >>> - bdrv_rw_co_entry(&rwco); >>> - } else { >>> - co = qemu_coroutine_create(bdrv_rw_co_entry, &rwco); >>> - bdrv_coroutine_enter(child->bs, co); >>> - BDRV_POLL_WHILE(child->bs, rwco.ret == NOT_DONE); >>> - } >>> - return rwco.ret; >>> + return bdrv_run_co(child->bs, bdrv_rw_co_entry, &rwco, &rwco.ret); >> >> So code that previously looped on NOT_DONE is obviously safe, while... >> >>> } >>> int bdrv_pwrite_zeroes(BdrvChild *child, int64_t offset, >>> @@ -2230,7 +2236,6 @@ typedef struct BdrvCoBlockStatusData { >>> int64_t *map; >>> BlockDriverState **file; >>> int ret; >>> - bool done; >>> } BdrvCoBlockStatusData; >>> int coroutine_fn bdrv_co_block_status_from_file(BlockDriverState *bs, >>> @@ -2492,7 +2497,6 @@ static void coroutine_fn bdrv_block_status_above_co_entry(void *opaque) >>> data->want_zero, >>> data->offset, data->bytes, >>> data->pnum, data->map, data->file); >>> - data->done = true; >>> aio_wait_kick(); >> >> ...code that looped on something else now has to be checked that data->ret is still being set to something useful. Fortunately that is true here. >> >>> @@ -2669,22 +2663,13 @@ static inline int >>> bdrv_rw_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos, >>> bool is_read) >>> { >>> - if (qemu_in_coroutine()) { >>> - return bdrv_co_rw_vmstate(bs, qiov, pos, is_read); >>> - } else { >>> - BdrvVmstateCo data = { >>> - .bs = bs, >>> - .qiov = qiov, >>> - .pos = pos, >>> - .is_read = is_read, >>> - .ret = -EINPROGRESS, >>> - }; >>> - Coroutine *co = qemu_coroutine_create(bdrv_co_rw_vmstate_entry, &data); >>> - >>> - bdrv_coroutine_enter(bs, co); >>> - BDRV_POLL_WHILE(bs, data.ret == -EINPROGRESS); >>> - return data.ret; >> >> It's a little harder to see whether -EINPROGRESS might ever be returned by a driver, but again this looks safe. > > Maybe add a comment regarding -EINPROGRESS before calling bdrv_run_co() in bdrv_rw_vmstate()? > > Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> > Hi! Actually, I've sent a v2 of this patch: "[PATCH v2] block: Factor out bdrv_run_co()" https://lists.gnu.org/archive/html/qemu-devel/2020-05/msg05437.html
diff --git a/block/io.c b/block/io.c index 7d30e61edc..c1badaadc9 100644 --- a/block/io.c +++ b/block/io.c @@ -891,6 +891,22 @@ static int bdrv_check_byte_request(BlockDriverState *bs, int64_t offset, return 0; } +static int bdrv_run_co(BlockDriverState *bs, CoroutineEntry *entry, + void *opaque, int *ret) +{ + if (qemu_in_coroutine()) { + /* Fast-path if already in coroutine context */ + entry(opaque); + } else { + Coroutine *co = qemu_coroutine_create(entry, opaque); + *ret = NOT_DONE; + bdrv_coroutine_enter(bs, co); + BDRV_POLL_WHILE(bs, *ret == NOT_DONE); + } + + return *ret; +} + typedef struct RwCo { BdrvChild *child; int64_t offset; @@ -923,25 +939,15 @@ static int bdrv_prwv_co(BdrvChild *child, int64_t offset, QEMUIOVector *qiov, bool is_write, BdrvRequestFlags flags) { - Coroutine *co; RwCo rwco = { .child = child, .offset = offset, .qiov = qiov, .is_write = is_write, - .ret = NOT_DONE, .flags = flags, }; - if (qemu_in_coroutine()) { - /* Fast-path if already in coroutine context */ - bdrv_rw_co_entry(&rwco); - } else { - co = qemu_coroutine_create(bdrv_rw_co_entry, &rwco); - bdrv_coroutine_enter(child->bs, co); - BDRV_POLL_WHILE(child->bs, rwco.ret == NOT_DONE); - } - return rwco.ret; + return bdrv_run_co(child->bs, bdrv_rw_co_entry, &rwco, &rwco.ret); } int bdrv_pwrite_zeroes(BdrvChild *child, int64_t offset, @@ -2230,7 +2236,6 @@ typedef struct BdrvCoBlockStatusData { int64_t *map; BlockDriverState **file; int ret; - bool done; } BdrvCoBlockStatusData; int coroutine_fn bdrv_co_block_status_from_file(BlockDriverState *bs, @@ -2492,7 +2497,6 @@ static void coroutine_fn bdrv_block_status_above_co_entry(void *opaque) data->want_zero, data->offset, data->bytes, data->pnum, data->map, data->file); - data->done = true; aio_wait_kick(); } @@ -2508,7 +2512,6 @@ static int bdrv_common_block_status_above(BlockDriverState *bs, int64_t *map, BlockDriverState **file) { - Coroutine *co; BdrvCoBlockStatusData data = { .bs = bs, .base = base, @@ -2518,18 +2521,9 @@ static int bdrv_common_block_status_above(BlockDriverState *bs, .pnum = pnum, .map = map, .file = file, - .done = false, }; - if (qemu_in_coroutine()) { - /* Fast-path if already in coroutine context */ - bdrv_block_status_above_co_entry(&data); - } else { - co = qemu_coroutine_create(bdrv_block_status_above_co_entry, &data); - bdrv_coroutine_enter(bs, co); - BDRV_POLL_WHILE(bs, !data.done); - } - return data.ret; + return bdrv_run_co(bs, bdrv_block_status_above_co_entry, &data, &data.ret); } int bdrv_block_status_above(BlockDriverState *bs, BlockDriverState *base, @@ -2669,22 +2663,13 @@ static inline int bdrv_rw_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos, bool is_read) { - if (qemu_in_coroutine()) { - return bdrv_co_rw_vmstate(bs, qiov, pos, is_read); - } else { - BdrvVmstateCo data = { - .bs = bs, - .qiov = qiov, - .pos = pos, - .is_read = is_read, - .ret = -EINPROGRESS, - }; - Coroutine *co = qemu_coroutine_create(bdrv_co_rw_vmstate_entry, &data); - - bdrv_coroutine_enter(bs, co); - BDRV_POLL_WHILE(bs, data.ret == -EINPROGRESS); - return data.ret; - } + BdrvVmstateCo data = { + .bs = bs, + .qiov = qiov, + .pos = pos, + .is_read = is_read, + }; + return bdrv_run_co(bs, bdrv_co_rw_vmstate_entry, &data, &data.ret); } int bdrv_save_vmstate(BlockDriverState *bs, const uint8_t *buf, @@ -2890,22 +2875,11 @@ early_exit: int bdrv_flush(BlockDriverState *bs) { - Coroutine *co; FlushCo flush_co = { .bs = bs, - .ret = NOT_DONE, }; - if (qemu_in_coroutine()) { - /* Fast-path if already in coroutine context */ - bdrv_flush_co_entry(&flush_co); - } else { - co = qemu_coroutine_create(bdrv_flush_co_entry, &flush_co); - bdrv_coroutine_enter(bs, co); - BDRV_POLL_WHILE(bs, flush_co.ret == NOT_DONE); - } - - return flush_co.ret; + return bdrv_run_co(bs, bdrv_flush_co_entry, &flush_co, &flush_co.ret); } typedef struct DiscardCo { @@ -3038,24 +3012,13 @@ out: int bdrv_pdiscard(BdrvChild *child, int64_t offset, int64_t bytes) { - Coroutine *co; DiscardCo rwco = { .child = child, .offset = offset, .bytes = bytes, - .ret = NOT_DONE, }; - if (qemu_in_coroutine()) { - /* Fast-path if already in coroutine context */ - bdrv_pdiscard_co_entry(&rwco); - } else { - co = qemu_coroutine_create(bdrv_pdiscard_co_entry, &rwco); - bdrv_coroutine_enter(child->bs, co); - BDRV_POLL_WHILE(child->bs, rwco.ret == NOT_DONE); - } - - return rwco.ret; + return bdrv_run_co(child->bs, bdrv_pdiscard_co_entry, &rwco, &rwco.ret); } int bdrv_co_ioctl(BlockDriverState *bs, int req, void *buf) @@ -3477,7 +3440,6 @@ static void coroutine_fn bdrv_truncate_co_entry(void *opaque) int bdrv_truncate(BdrvChild *child, int64_t offset, bool exact, PreallocMode prealloc, BdrvRequestFlags flags, Error **errp) { - Coroutine *co; TruncateCo tco = { .child = child, .offset = offset, @@ -3485,17 +3447,7 @@ int bdrv_truncate(BdrvChild *child, int64_t offset, bool exact, .prealloc = prealloc, .flags = flags, .errp = errp, - .ret = NOT_DONE, }; - if (qemu_in_coroutine()) { - /* Fast-path if already in coroutine context */ - bdrv_truncate_co_entry(&tco); - } else { - co = qemu_coroutine_create(bdrv_truncate_co_entry, &tco); - bdrv_coroutine_enter(child->bs, co); - BDRV_POLL_WHILE(child->bs, tco.ret == NOT_DONE); - } - - return tco.ret; + return bdrv_run_co(child->bs, bdrv_truncate_co_entry, &tco, &tco.ret); }
We have a few bdrv_*() functions that can either spawn a new coroutine and wait for it with BDRV_POLL_WHILE() or use a fastpath if they are alreeady running in a coroutine. All of them duplicate basically the same code. Factor the common code into a new function bdrv_run_co(). Signed-off-by: Kevin Wolf <kwolf@redhat.com> --- block/io.c | 104 +++++++++++++++-------------------------------------- 1 file changed, 28 insertions(+), 76 deletions(-)