| Message ID | 1450867706-19860-2-git-send-email-pbonzini@redhat.com |
|---|---|
| State | New |
| Headers | show |
On 23.12.2015 11:48, Paolo Bonzini wrote: > bdrv_close is used when ejecting a medium. Is it still? Other than it maybe being indirectly called through bdrv_delete(), it shouldn't be. > Use a drained section to ensure > that all I/O goes to either the old medium or the bitbucket. Since the BDS will be deleted after bdrv_close() has been called, where else would the I/O go now? Max > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> > --- > block.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/block.c b/block.c > index 411edbf..01655de 100644 > --- a/block.c > +++ b/block.c > @@ -2154,9 +2154,10 @@ void bdrv_close(BlockDriverState *bs) > bdrv_io_limits_disable(bs); > } > > - bdrv_drain(bs); /* complete I/O */ > + bdrv_drained_begin(bs); /* complete I/O */ > bdrv_flush(bs); > bdrv_drain(bs); /* in case flush left pending I/O */ > + > notifier_list_notify(&bs->close_notifiers, bs); > > if (bs->blk) { > @@ -2206,6 +2207,7 @@ void bdrv_close(BlockDriverState *bs) > g_free(ban); > } > QLIST_INIT(&bs->aio_notifiers); > + bdrv_drained_end(bs); > } > > void bdrv_close_all(void) >
> On 23.12.2015 11:48, Paolo Bonzini wrote: > > bdrv_close is used when ejecting a medium. > > Is it still? Other than it maybe being indirectly called through > bdrv_delete(), it shouldn't be. Yes, through blk_remove_bs -> bdrv_unref -> bdrv_delete. > > Use a drained section to ensure > > that all I/O goes to either the old medium or the bitbucket. > > Since the BDS will be deleted after bdrv_close() has been called, where > else would the I/O go now? The ioeventfd could be processed during bs->drv->bdrv_close. For example I/O could be submitted while qcow2_close's qcow2_cache_flush yields, and the result would probably be corrupted metadata. Paolo > Max > > > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> > > --- > > block.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/block.c b/block.c > > index 411edbf..01655de 100644 > > --- a/block.c > > +++ b/block.c > > @@ -2154,9 +2154,10 @@ void bdrv_close(BlockDriverState *bs) > > bdrv_io_limits_disable(bs); > > } > > > > - bdrv_drain(bs); /* complete I/O */ > > + bdrv_drained_begin(bs); /* complete I/O */ > > bdrv_flush(bs); > > bdrv_drain(bs); /* in case flush left pending I/O */ > > + > > notifier_list_notify(&bs->close_notifiers, bs); > > > > if (bs->blk) { > > @@ -2206,6 +2207,7 @@ void bdrv_close(BlockDriverState *bs) > > g_free(ban); > > } > > QLIST_INIT(&bs->aio_notifiers); > > + bdrv_drained_end(bs); > > } > > > > void bdrv_close_all(void) > > > > >
On 23.12.2015 22:55, Paolo Bonzini wrote: > >> On 23.12.2015 11:48, Paolo Bonzini wrote: >>> bdrv_close is used when ejecting a medium. >> >> Is it still? Other than it maybe being indirectly called through >> bdrv_delete(), it shouldn't be. > > Yes, through blk_remove_bs -> bdrv_unref -> bdrv_delete. OK, I was asking because bdrv_close() was invoked directly by the ejection code until recently and thought that maybe you were referring to that, and that there might have been a way for I/O to spill to the new medium if one issued a change command. >>> Use a drained section to ensure >>> that all I/O goes to either the old medium or the bitbucket. >> >> Since the BDS will be deleted after bdrv_close() has been called, where >> else would the I/O go now? > > The ioeventfd could be processed during bs->drv->bdrv_close. For > example I/O could be submitted while qcow2_close's qcow2_cache_flush > yields, and the result would probably be corrupted metadata. Ah, OK, so you meant “Either all or no I/O should go to the medium”, I thought it was about the fact that I/O might go somewhere else than the old medium or /dev/null (e.g. the new medium in case of a change). That makes more sense now, thanks! :-) Applied to my block tree: https://github.com/XanClic/qemu/commits/block Max > > Paolo > >> Max >> >>> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> >>> --- >>> block.c | 4 +++- >>> 1 file changed, 3 insertions(+), 1 deletion(-) >>> >>> diff --git a/block.c b/block.c >>> index 411edbf..01655de 100644 >>> --- a/block.c >>> +++ b/block.c >>> @@ -2154,9 +2154,10 @@ void bdrv_close(BlockDriverState *bs) >>> bdrv_io_limits_disable(bs); >>> } >>> >>> - bdrv_drain(bs); /* complete I/O */ >>> + bdrv_drained_begin(bs); /* complete I/O */ >>> bdrv_flush(bs); >>> bdrv_drain(bs); /* in case flush left pending I/O */ >>> + >>> notifier_list_notify(&bs->close_notifiers, bs); >>> >>> if (bs->blk) { >>> @@ -2206,6 +2207,7 @@ void bdrv_close(BlockDriverState *bs) >>> g_free(ban); >>> } >>> QLIST_INIT(&bs->aio_notifiers); >>> + bdrv_drained_end(bs); >>> } >>> >>> void bdrv_close_all(void) >>> >> >> >>
diff --git a/block.c b/block.c index 411edbf..01655de 100644 --- a/block.c +++ b/block.c @@ -2154,9 +2154,10 @@ void bdrv_close(BlockDriverState *bs) bdrv_io_limits_disable(bs); } - bdrv_drain(bs); /* complete I/O */ + bdrv_drained_begin(bs); /* complete I/O */ bdrv_flush(bs); bdrv_drain(bs); /* in case flush left pending I/O */ + notifier_list_notify(&bs->close_notifiers, bs); if (bs->blk) { @@ -2206,6 +2207,7 @@ void bdrv_close(BlockDriverState *bs) g_free(ban); } QLIST_INIT(&bs->aio_notifiers); + bdrv_drained_end(bs); } void bdrv_close_all(void)
bdrv_close is used when ejecting a medium. Use a drained section to ensure that all I/O goes to either the old medium or the bitbucket. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- block.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)