| Message ID | 1442497700-2536-13-git-send-email-kwolf@redhat.com |
|---|---|
| State | New |
| Headers | show |
On 17.09.2015 15:48, Kevin Wolf wrote: > Signed-off-by: Kevin Wolf <kwolf@redhat.com> > --- > block.c | 3 +++ > include/block/block_int.h | 2 ++ > 2 files changed, 5 insertions(+) Reviewed-by: Max Reitz <mreitz@redhat.com>
On Thu 17 Sep 2015 03:48:16 PM CEST, Kevin Wolf wrote: > @@ -1090,6 +1090,7 @@ static BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs, > }; > > QLIST_INSERT_HEAD(&parent_bs->children, child, next); > + QLIST_INSERT_HEAD(&child_bs->parents, child, next_parent); > > return child; > } Ok, I'm probably slow today, but what is this used for? :-? And why is it called 'parents'? The list doesn't contain pointers to the parents of child_bs, but to child_bs itself... I would expect a BdrvChild *parent, with parent->bs = parent_bs. Berto
Am 28.09.2015 um 15:09 hat Alberto Garcia geschrieben: > On Thu 17 Sep 2015 03:48:16 PM CEST, Kevin Wolf wrote: > > > @@ -1090,6 +1090,7 @@ static BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs, > > }; > > > > QLIST_INSERT_HEAD(&parent_bs->children, child, next); > > + QLIST_INSERT_HEAD(&child_bs->parents, child, next_parent); > > > > return child; > > } > > Ok, I'm probably slow today, but what is this used for? :-? And why is > it called 'parents'? The list doesn't contain pointers to the parents of > child_bs, but to child_bs itself... > > I would expect a BdrvChild *parent, with parent->bs = parent_bs. It's the list of BdrvChild objects that point to the given BlockDriverState. This is good enough for updating the pointers. If we ever need the actual parent BDS, we can add a pointer to BdrvChild. Kevin
On Tue 29 Sep 2015 02:21:37 PM CEST, Kevin Wolf wrote: >> > @@ -1090,6 +1090,7 @@ static BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs, >> > }; >> > >> > QLIST_INSERT_HEAD(&parent_bs->children, child, next); >> > + QLIST_INSERT_HEAD(&child_bs->parents, child, next_parent); >> > >> > return child; >> > } >> >> Ok, I'm probably slow today, but what is this used for? :-? And why >> is it called 'parents'? The list doesn't contain pointers to the >> parents of child_bs, but to child_bs itself... > > It's the list of BdrvChild objects that point to the given > BlockDriverState. Ok I see now. I think the names here are misleading, 'parent' means the BdrvChild object, not parent_bs. The name child_bs->parents suggests that you can actually iterate over the BDSs that have child_bs as a child, but that's not the case, it's a mechanism that allows children to change the pointers that are pointing at them. I'm not sure what a better name would be ("reverse refs"?), but at least I think this deserves a comment. Berto
diff --git a/block.c b/block.c index 7930f3c..c196f83 100644 --- a/block.c +++ b/block.c @@ -1090,6 +1090,7 @@ static BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs, }; QLIST_INSERT_HEAD(&parent_bs->children, child, next); + QLIST_INSERT_HEAD(&child_bs->parents, child, next_parent); return child; } @@ -1097,6 +1098,7 @@ static BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs, void bdrv_detach_child(BdrvChild *child) { QLIST_REMOVE(child, next); + QLIST_REMOVE(child, next_parent); g_free(child); } @@ -2037,6 +2039,7 @@ static void bdrv_move_reference_fields(BlockDriverState *bs_dest, /* keep the same entry in bdrv_states */ bs_dest->device_list = bs_src->device_list; bs_dest->blk = bs_src->blk; + bs_dest->parents = bs_src->parents; memcpy(bs_dest->op_blockers, bs_src->op_blockers, sizeof(bs_dest->op_blockers)); diff --git a/include/block/block_int.h b/include/block/block_int.h index cfcae52..52ea7c0 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -339,6 +339,7 @@ struct BdrvChild { BlockDriverState *bs; const BdrvChildRole *role; QLIST_ENTRY(BdrvChild) next; + QLIST_ENTRY(BdrvChild) next_parent; }; /* @@ -445,6 +446,7 @@ struct BlockDriverState { * parent node of this node. */ BlockDriverState *inherits_from; QLIST_HEAD(, BdrvChild) children; + QLIST_HEAD(, BdrvChild) parents; QDict *options; BlockdevDetectZeroesOptions detect_zeroes;
Signed-off-by: Kevin Wolf <kwolf@redhat.com> --- block.c | 3 +++ include/block/block_int.h | 2 ++ 2 files changed, 5 insertions(+)