From 9def6082cf885fbb2e8e719d5055109c8a04b885 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Mon, 11 Sep 2023 11:46:20 +0200 Subject: [PATCH] block: Mark bdrv_add/del_child() and caller GRAPH_WRLOCK The functions read the parents list in the generic block layer, so we need to hold the graph lock already there. The BlockDriver implementations actually modify the graph, so it has to be a writer lock. Signed-off-by: Kevin Wolf Reviewed-by: Emanuele Giuseppe Esposito Reviewed-by: Stefan Hajnoczi Message-ID: <20230911094620.45040-22-kwolf@redhat.com> Signed-off-by: Kevin Wolf --- block/quorum.c | 23 ++++++----------------- blockdev.c | 17 +++++++++++------ include/block/block-global-state.h | 8 +++++--- include/block/block_int-common.h | 9 +++++---- 4 files changed, 27 insertions(+), 30 deletions(-) diff --git a/block/quorum.c b/block/quorum.c index 620a50ba2c..05220cab7f 100644 --- a/block/quorum.c +++ b/block/quorum.c @@ -1066,8 +1066,8 @@ static void quorum_close(BlockDriverState *bs) g_free(s->children); } -static void quorum_add_child(BlockDriverState *bs, BlockDriverState *child_bs, - Error **errp) +static void GRAPH_WRLOCK +quorum_add_child(BlockDriverState *bs, BlockDriverState *child_bs, Error **errp) { BDRVQuorumState *s = bs->opaque; BdrvChild *child; @@ -1093,29 +1093,22 @@ static void quorum_add_child(BlockDriverState *bs, BlockDriverState *child_bs, } s->next_child_index++; - bdrv_drained_begin(bs); - /* We can safely add the child now */ bdrv_ref(child_bs); - bdrv_graph_wrlock(child_bs); child = bdrv_attach_child(bs, child_bs, indexstr, &child_of_bds, BDRV_CHILD_DATA, errp); - bdrv_graph_wrunlock(); if (child == NULL) { s->next_child_index--; - goto out; + return; } s->children = g_renew(BdrvChild *, s->children, s->num_children + 1); s->children[s->num_children++] = child; quorum_refresh_flags(bs); - -out: - bdrv_drained_end(bs); } -static void quorum_del_child(BlockDriverState *bs, BdrvChild *child, - Error **errp) +static void GRAPH_WRLOCK +quorum_del_child(BlockDriverState *bs, BdrvChild *child, Error **errp) { BDRVQuorumState *s = bs->opaque; char indexstr[INDEXSTR_LEN]; @@ -1145,18 +1138,14 @@ static void quorum_del_child(BlockDriverState *bs, BdrvChild *child, s->next_child_index--; } - bdrv_drained_begin(bs); - /* We can safely remove this child now */ memmove(&s->children[i], &s->children[i + 1], (s->num_children - i - 1) * sizeof(BdrvChild *)); s->children = g_renew(BdrvChild *, s->children, --s->num_children); - bdrv_graph_wrlock(NULL); + bdrv_unref_child(bs, child); - bdrv_graph_wrunlock(); quorum_refresh_flags(bs); - bdrv_drained_end(bs); } static void quorum_gather_child_options(BlockDriverState *bs, QDict *target, diff --git a/blockdev.c b/blockdev.c index 372eaf198c..325b7a3bef 100644 --- a/blockdev.c +++ b/blockdev.c @@ -3545,8 +3545,8 @@ out: aio_context_release(aio_context); } -static BdrvChild *bdrv_find_child(BlockDriverState *parent_bs, - const char *child_name) +static BdrvChild * GRAPH_RDLOCK +bdrv_find_child(BlockDriverState *parent_bs, const char *child_name) { BdrvChild *child; @@ -3565,9 +3565,11 @@ void qmp_x_blockdev_change(const char *parent, const char *child, BlockDriverState *parent_bs, *new_bs = NULL; BdrvChild *p_child; + bdrv_graph_wrlock(NULL); + parent_bs = bdrv_lookup_bs(parent, parent, errp); if (!parent_bs) { - return; + goto out; } if (!child == !node) { @@ -3576,7 +3578,7 @@ void qmp_x_blockdev_change(const char *parent, const char *child, } else { error_setg(errp, "Either child or node must be specified"); } - return; + goto out; } if (child) { @@ -3584,7 +3586,7 @@ void qmp_x_blockdev_change(const char *parent, const char *child, if (!p_child) { error_setg(errp, "Node '%s' does not have child '%s'", parent, child); - return; + goto out; } bdrv_del_child(parent_bs, p_child, errp); } @@ -3593,10 +3595,13 @@ void qmp_x_blockdev_change(const char *parent, const char *child, new_bs = bdrv_find_node(node); if (!new_bs) { error_setg(errp, "Node '%s' not found", node); - return; + goto out; } bdrv_add_child(parent_bs, new_bs, errp); } + +out: + bdrv_graph_wrunlock(); } BlockJobInfoList *qmp_query_block_jobs(Error **errp) diff --git a/include/block/block-global-state.h b/include/block/block-global-state.h index 0f6df8f1a2..f31660c7b1 100644 --- a/include/block/block-global-state.h +++ b/include/block/block-global-state.h @@ -276,9 +276,11 @@ int bdrv_try_change_aio_context(BlockDriverState *bs, AioContext *ctx, int bdrv_probe_blocksizes(BlockDriverState *bs, BlockSizes *bsz); int bdrv_probe_geometry(BlockDriverState *bs, HDGeometry *geo); -void bdrv_add_child(BlockDriverState *parent, BlockDriverState *child, - Error **errp); -void bdrv_del_child(BlockDriverState *parent, BdrvChild *child, Error **errp); +void GRAPH_WRLOCK +bdrv_add_child(BlockDriverState *parent, BlockDriverState *child, Error **errp); + +void GRAPH_WRLOCK +bdrv_del_child(BlockDriverState *parent, BdrvChild *child, Error **errp); /** * diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h index 3feb67ec4a..2ca3758cb8 100644 --- a/include/block/block_int-common.h +++ b/include/block/block_int-common.h @@ -393,10 +393,11 @@ struct BlockDriver { */ int (*bdrv_probe_geometry)(BlockDriverState *bs, HDGeometry *geo); - void (*bdrv_add_child)(BlockDriverState *parent, BlockDriverState *child, - Error **errp); - void (*bdrv_del_child)(BlockDriverState *parent, BdrvChild *child, - Error **errp); + void GRAPH_WRLOCK_PTR (*bdrv_add_child)( + BlockDriverState *parent, BlockDriverState *child, Error **errp); + + void GRAPH_WRLOCK_PTR (*bdrv_del_child)( + BlockDriverState *parent, BdrvChild *child, Error **errp); /** * Informs the block driver that a permission change is intended. The