| Message ID | 20190218161822.3573-12-kwolf@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | block: bdrv_set_aio_context() related fixes | expand |
On 2/18/19 10:18 AM, Kevin Wolf wrote: > Now that bdrv_set_aio_context() works inside drained sections, it can > also use the real drain function instead of open coding something > similar. > > Signed-off-by: Kevin Wolf <kwolf@redhat.com> > --- > block.c | 14 +++++--------- > 1 file changed, 5 insertions(+), 9 deletions(-) > > diff --git a/block.c b/block.c > index aefb5701f5..7024172db8 100644 > --- a/block.c > +++ b/block.c > @@ -5268,18 +5268,15 @@ void bdrv_attach_aio_context(BlockDriverState *bs, > bs->walking_aio_notifiers = false; > } > > +/* The caller must own the AioContext lock for the old AioContext of bs, but it > + * must not own the AioContext lock for new_context. */ Is this comment still accurate, given > void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context) > { > - AioContext *ctx = bdrv_get_aio_context(bs); > - > - if (ctx == new_context) { > + if (bdrv_get_aio_context(bs) == new_context) { > return; > } the short-circuiting when the old context is the new context? > > - aio_disable_external(ctx); > - bdrv_parent_drained_begin(bs, NULL, false); > - bdrv_drain(bs); /* ensure there are no in-flight requests */ > - > + bdrv_drained_begin(bs); > bdrv_detach_aio_context(bs); > > /* This function executes in the old AioContext so acquire the new one in > @@ -5287,8 +5284,7 @@ void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context) > */ > aio_context_acquire(new_context); > bdrv_attach_aio_context(bs, new_context); > - bdrv_parent_drained_end(bs, NULL, false); > - aio_enable_external(ctx); > + bdrv_drained_end(bs); > aio_context_release(new_context); > } > >
Am 18.02.2019 um 21:57 hat Eric Blake geschrieben: > On 2/18/19 10:18 AM, Kevin Wolf wrote: > > Now that bdrv_set_aio_context() works inside drained sections, it can > > also use the real drain function instead of open coding something > > similar. > > > > Signed-off-by: Kevin Wolf <kwolf@redhat.com> > > --- > > block.c | 14 +++++--------- > > 1 file changed, 5 insertions(+), 9 deletions(-) > > > > diff --git a/block.c b/block.c > > index aefb5701f5..7024172db8 100644 > > --- a/block.c > > +++ b/block.c > > @@ -5268,18 +5268,15 @@ void bdrv_attach_aio_context(BlockDriverState *bs, > > bs->walking_aio_notifiers = false; > > } > > > > +/* The caller must own the AioContext lock for the old AioContext of bs, but it > > + * must not own the AioContext lock for new_context. */ > > Is this comment still accurate, given > > > void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context) > > { > > - AioContext *ctx = bdrv_get_aio_context(bs); > > - > > - if (ctx == new_context) { > > + if (bdrv_get_aio_context(bs) == new_context) { > > return; > > } > > the short-circuiting when the old context is the new context? Hm, yes, old == new is an exception where you quite obviously can't have old locked and new unlocked at the same time. So is adding this enough? (unless new_context is the same as the current context of bs) Kevin
On 2/19/19 5:23 AM, Kevin Wolf wrote: > Am 18.02.2019 um 21:57 hat Eric Blake geschrieben: >> On 2/18/19 10:18 AM, Kevin Wolf wrote: >>> Now that bdrv_set_aio_context() works inside drained sections, it can >>> also use the real drain function instead of open coding something >>> similar. >>> >>> Signed-off-by: Kevin Wolf <kwolf@redhat.com> >>> --- >>> +/* The caller must own the AioContext lock for the old AioContext of bs, but it >>> + * must not own the AioContext lock for new_context. */ >> >> Is this comment still accurate, given >> >>> void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context) >>> { >>> - AioContext *ctx = bdrv_get_aio_context(bs); >>> - >>> - if (ctx == new_context) { >>> + if (bdrv_get_aio_context(bs) == new_context) { >>> return; >>> } >> >> the short-circuiting when the old context is the new context? > > Hm, yes, old == new is an exception where you quite obviously can't have > old locked and new unlocked at the same time. > > So is adding this enough? > > (unless new_context is the same as the current context of bs) Works for me.
diff --git a/block.c b/block.c index aefb5701f5..7024172db8 100644 --- a/block.c +++ b/block.c @@ -5268,18 +5268,15 @@ void bdrv_attach_aio_context(BlockDriverState *bs, bs->walking_aio_notifiers = false; } +/* The caller must own the AioContext lock for the old AioContext of bs, but it + * must not own the AioContext lock for new_context. */ void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context) { - AioContext *ctx = bdrv_get_aio_context(bs); - - if (ctx == new_context) { + if (bdrv_get_aio_context(bs) == new_context) { return; } - aio_disable_external(ctx); - bdrv_parent_drained_begin(bs, NULL, false); - bdrv_drain(bs); /* ensure there are no in-flight requests */ - + bdrv_drained_begin(bs); bdrv_detach_aio_context(bs); /* This function executes in the old AioContext so acquire the new one in @@ -5287,8 +5284,7 @@ void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context) */ aio_context_acquire(new_context); bdrv_attach_aio_context(bs, new_context); - bdrv_parent_drained_end(bs, NULL, false); - aio_enable_external(ctx); + bdrv_drained_end(bs); aio_context_release(new_context); }
Now that bdrv_set_aio_context() works inside drained sections, it can also use the real drain function instead of open coding something similar. Signed-off-by: Kevin Wolf <kwolf@redhat.com> --- block.c | 14 +++++--------- 1 file changed, 5 insertions(+), 9 deletions(-)