| Message ID | 1441183880-26993-2-git-send-email-wency@cn.fujitsu.com |
|---|---|
| State | New |
| Headers | show |
On 09/02/2015 02:51 AM, Wen Congyang wrote: > Signed-off-by: Wen Congyang <wency@cn.fujitsu.com> > --- > block/block-backend.c | 24 ++++++++++++++++++++++++ > include/sysemu/block-backend.h | 2 ++ > 2 files changed, 26 insertions(+) > > diff --git a/block/block-backend.c b/block/block-backend.c > index aee8a12..72d8b2c 100644 > --- a/block/block-backend.c > +++ b/block/block-backend.c > @@ -344,6 +344,30 @@ void *blk_get_attached_dev(BlockBackend *blk) > } > > /* > + * Disable to attach a device mode to @blk. s/to attach/attaching/ s/mode/model/ But I'm not even sure this patch makes sense. I'd rather see Max's work go in that allows for a BB without a BDS as representing a drive without media, because then it is clear - either a BB has an associated BDS (and cannot attach another one), or it does not (and attaching is fine). > + * Return 0 on success, -EBUSY when a device model is attached already. > + */ > +int blk_disable_attach_dev(BlockBackend *blk) > +{ > + if (blk->dev) { > + return blk->dev == (void *)-1 ? 0 : -EBUSY; > + } > + > + blk->dev = (void *)-1; > + return 0; > +} > + > +/* > + * Enable to attach a device mode to @blk. > + */ > +void blk_enable_attach_dev(BlockBackend *blk) > +{ > + if (blk->dev == (void *)-1) { At the very least, if we allow a special sentinel to represent a BB without a BDS (other than NULL, the way Max's series does it), it should at least be wrapped by a macro, rather than using '(void *)-1' at multiple call sites.
On 09/02/2015 11:37 PM, Eric Blake wrote: > On 09/02/2015 02:51 AM, Wen Congyang wrote: >> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com> >> --- >> block/block-backend.c | 24 ++++++++++++++++++++++++ >> include/sysemu/block-backend.h | 2 ++ >> 2 files changed, 26 insertions(+) >> >> diff --git a/block/block-backend.c b/block/block-backend.c >> index aee8a12..72d8b2c 100644 >> --- a/block/block-backend.c >> +++ b/block/block-backend.c >> @@ -344,6 +344,30 @@ void *blk_get_attached_dev(BlockBackend *blk) >> } >> >> /* >> + * Disable to attach a device mode to @blk. > > s/to attach/attaching/ > s/mode/model/ > > But I'm not even sure this patch makes sense. I'd rather see Max's work > go in that allows for a BB without a BDS as representing a drive without > media, because then it is clear - either a BB has an associated BDS (and > cannot attach another one), or it does not (and attaching is fine). Hmm, I think the API's name cause a misunderstanding. These APIs are used to check if the BB is used by some block device. It is very useful if we allow references for backing files. If the backing file referes an existing BDS that with BB, the block device can't use this BB at the same time. Thanks Wen Congyang > >> + * Return 0 on success, -EBUSY when a device model is attached already. >> + */ >> +int blk_disable_attach_dev(BlockBackend *blk) >> +{ >> + if (blk->dev) { >> + return blk->dev == (void *)-1 ? 0 : -EBUSY; >> + } >> + >> + blk->dev = (void *)-1; >> + return 0; >> +} >> + >> +/* >> + * Enable to attach a device mode to @blk. >> + */ >> +void blk_enable_attach_dev(BlockBackend *blk) >> +{ >> + if (blk->dev == (void *)-1) { > > At the very least, if we allow a special sentinel to represent a BB > without a BDS (other than NULL, the way Max's series does it), it should > at least be wrapped by a macro, rather than using '(void *)-1' at > multiple call sites. >
diff --git a/block/block-backend.c b/block/block-backend.c index aee8a12..72d8b2c 100644 --- a/block/block-backend.c +++ b/block/block-backend.c @@ -344,6 +344,30 @@ void *blk_get_attached_dev(BlockBackend *blk) } /* + * Disable to attach a device mode to @blk. + * Return 0 on success, -EBUSY when a device model is attached already. + */ +int blk_disable_attach_dev(BlockBackend *blk) +{ + if (blk->dev) { + return blk->dev == (void *)-1 ? 0 : -EBUSY; + } + + blk->dev = (void *)-1; + return 0; +} + +/* + * Enable to attach a device mode to @blk. + */ +void blk_enable_attach_dev(BlockBackend *blk) +{ + if (blk->dev == (void *)-1) { + blk->dev = NULL; + } +} + +/* * Set @blk's device model callbacks to @ops. * @opaque is the opaque argument to pass to the callbacks. * This is for use by device models. diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h index 8fc960f..7619a9f 100644 --- a/include/sysemu/block-backend.h +++ b/include/sysemu/block-backend.h @@ -80,6 +80,8 @@ int blk_attach_dev(BlockBackend *blk, void *dev); void blk_attach_dev_nofail(BlockBackend *blk, void *dev); void blk_detach_dev(BlockBackend *blk, void *dev); void *blk_get_attached_dev(BlockBackend *blk); +int blk_disable_attach_dev(BlockBackend *blk); +void blk_enable_attach_dev(BlockBackend *blk); void blk_set_dev_ops(BlockBackend *blk, const BlockDevOps *ops, void *opaque); int blk_read(BlockBackend *blk, int64_t sector_num, uint8_t *buf, int nb_sectors);
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com> --- block/block-backend.c | 24 ++++++++++++++++++++++++ include/sysemu/block-backend.h | 2 ++ 2 files changed, 26 insertions(+)