bdrv_replace_child_noperm() is the heart of block graph changes. It is called when a node is inserted, removed, or replaced. These changes happen without notifying parents in the graph, so it is currently not possible to monitor changes.
Add BdrvChildClass callbacks to propagate attach/detach operations to the roots of the graph. The next commit will introduce a BlockBackend API for monitoring changes using this mechanism. Signed-off-by: Stefan Hajnoczi <[email protected]> Reviewed-by: Eric Blake <[email protected]> --- include/block/block_int-common.h | 11 +++++++ block.c | 56 +++++++++++++++++++++++++------- 2 files changed, 56 insertions(+), 11 deletions(-) diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h index 034c0634c8..0368a3191c 100644 --- a/include/block/block_int-common.h +++ b/include/block/block_int-common.h @@ -963,6 +963,17 @@ struct BdrvChildClass { void GRAPH_RDLOCK_PTR (*activate)(BdrvChild *child, Error **errp); int GRAPH_RDLOCK_PTR (*inactivate)(BdrvChild *child); + /* + * Optional callbacks when a descendant (child, grandchild, etc) attaches + * or detaches a BlockDriverState. Allows monitoring changes to the graph. + * + * Called after ->attach() and before ->detach(). + */ + void GRAPH_WRLOCK_PTR (*propagate_attach)(BdrvChild *self, + BdrvChild *descendant); + void GRAPH_WRLOCK_PTR (*propagate_detach)(BdrvChild *self, + BdrvChild *descendant); + void GRAPH_WRLOCK_PTR (*attach)(BdrvChild *child); void GRAPH_WRLOCK_PTR (*detach)(BdrvChild *child); diff --git a/block.c b/block.c index 8848e9a7ed..e1480dda04 100644 --- a/block.c +++ b/block.c @@ -1497,6 +1497,32 @@ static void GRAPH_WRLOCK bdrv_child_cb_detach(BdrvChild *child) } } +static void GRAPH_WRLOCK +bdrv_child_cb_propagate_attach(BdrvChild *self, BdrvChild *descendant) +{ + BlockDriverState *bs = self->opaque; + BdrvChild *c; + + QLIST_FOREACH(c, &bs->parents, next_parent) { + if (c->klass->propagate_attach) { + c->klass->propagate_attach(c, descendant); + } + } +} + +static void GRAPH_WRLOCK +bdrv_child_cb_propagate_detach(BdrvChild *self, BdrvChild *descendant) +{ + BlockDriverState *bs = self->opaque; + BdrvChild *c; + + QLIST_FOREACH(c, &bs->parents, next_parent) { + if (c->klass->propagate_detach) { + c->klass->propagate_detach(c, descendant); + } + } +} + static int bdrv_child_cb_update_filename(BdrvChild *c, BlockDriverState *base, const char *filename, bool backing_mask_protocol, @@ -1519,17 +1545,19 @@ AioContext *child_of_bds_get_parent_aio_context(BdrvChild *c) } const BdrvChildClass child_of_bds = { - .parent_is_bds = true, - .get_parent_desc = bdrv_child_get_parent_desc, - .inherit_options = bdrv_inherited_options, - .drained_begin = bdrv_child_cb_drained_begin, - .drained_poll = bdrv_child_cb_drained_poll, - .drained_end = bdrv_child_cb_drained_end, - .attach = bdrv_child_cb_attach, - .detach = bdrv_child_cb_detach, - .inactivate = bdrv_child_cb_inactivate, - .change_aio_ctx = bdrv_child_cb_change_aio_ctx, - .update_filename = bdrv_child_cb_update_filename, + .parent_is_bds = true, + .get_parent_desc = bdrv_child_get_parent_desc, + .inherit_options = bdrv_inherited_options, + .drained_begin = bdrv_child_cb_drained_begin, + .drained_poll = bdrv_child_cb_drained_poll, + .drained_end = bdrv_child_cb_drained_end, + .attach = bdrv_child_cb_attach, + .detach = bdrv_child_cb_detach, + .propagate_attach = bdrv_child_cb_propagate_attach, + .propagate_detach = bdrv_child_cb_propagate_detach, + .inactivate = bdrv_child_cb_inactivate, + .change_aio_ctx = bdrv_child_cb_change_aio_ctx, + .update_filename = bdrv_child_cb_update_filename, .get_parent_aio_context = child_of_bds_get_parent_aio_context, }; @@ -2967,6 +2995,9 @@ bdrv_replace_child_noperm(BdrvChild *child, BlockDriverState *new_bs) } if (old_bs) { + if (child->klass->propagate_detach) { + child->klass->propagate_detach(child, child); + } if (child->klass->detach) { child->klass->detach(child); } @@ -2980,6 +3011,9 @@ bdrv_replace_child_noperm(BdrvChild *child, BlockDriverState *new_bs) if (child->klass->attach) { child->klass->attach(child); } + if (child->klass->propagate_attach) { + child->klass->propagate_attach(child, child); + } } /* -- 2.51.0
