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[PATCH v5 09/31] block: introduce assert_bdrv_graph_writable
From: |
Emanuele Giuseppe Esposito |
Subject: |
[PATCH v5 09/31] block: introduce assert_bdrv_graph_writable |
Date: |
Wed, 24 Nov 2021 01:43:56 -0500 |
We want to be sure that the functions that write the child and
parent list of a bs are under BQL and drain.
BQL prevents from concurrent writings from the GS API, while
drains protect from I/O.
TODO: drains are missing in some functions using this assert.
Therefore a proper assertion will fail. Because adding drains
requires additional discussions, they will be added in future
series.
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
---
include/block/block_int-global-state.h | 10 +++++++++-
block.c | 4 ++++
block/io.c | 11 +++++++++++
3 files changed, 24 insertions(+), 1 deletion(-)
diff --git a/include/block/block_int-global-state.h
b/include/block/block_int-global-state.h
index a1b7d0579d..fa96e8b449 100644
--- a/include/block/block_int-global-state.h
+++ b/include/block/block_int-global-state.h
@@ -312,4 +312,12 @@ void bdrv_remove_aio_context_notifier(BlockDriverState *bs,
*/
void bdrv_drain_all_end_quiesce(BlockDriverState *bs);
-#endif /* BLOCK_INT_GLOBAL_STATE*/
+/**
+ * Make sure that the function is running under both drain and BQL.
+ * The latter protects from concurrent writings
+ * from the GS API, while the former prevents concurrent reads
+ * from I/O.
+ */
+void assert_bdrv_graph_writable(BlockDriverState *bs);
+
+#endif /* BLOCK_INT_GLOBAL_STATE */
diff --git a/block.c b/block.c
index 198ec636ff..522a273140 100644
--- a/block.c
+++ b/block.c
@@ -1416,6 +1416,7 @@ static void bdrv_child_cb_attach(BdrvChild *child)
{
BlockDriverState *bs = child->opaque;
+ assert_bdrv_graph_writable(bs);
QLIST_INSERT_HEAD(&bs->children, child, next);
if (child->role & BDRV_CHILD_COW) {
@@ -1435,6 +1436,7 @@ static void bdrv_child_cb_detach(BdrvChild *child)
bdrv_unapply_subtree_drain(child, bs);
+ assert_bdrv_graph_writable(bs);
QLIST_REMOVE(child, next);
}
@@ -2818,6 +2820,7 @@ static void bdrv_replace_child_noperm(BdrvChild **childp,
if (child->klass->detach) {
child->klass->detach(child);
}
+ assert_bdrv_graph_writable(old_bs);
QLIST_REMOVE(child, next_parent);
}
@@ -2827,6 +2830,7 @@ static void bdrv_replace_child_noperm(BdrvChild **childp,
}
if (new_bs) {
+ assert_bdrv_graph_writable(new_bs);
QLIST_INSERT_HEAD(&new_bs->parents, child, next_parent);
/*
diff --git a/block/io.c b/block/io.c
index cb095deeec..3be08cad29 100644
--- a/block/io.c
+++ b/block/io.c
@@ -734,6 +734,17 @@ void bdrv_drain_all(void)
bdrv_drain_all_end();
}
+void assert_bdrv_graph_writable(BlockDriverState *bs)
+{
+ /*
+ * TODO: this function is incomplete. Because the users of this
+ * assert lack the necessary drains, check only for BQL.
+ * Once the necessary drains are added,
+ * assert also for qatomic_read(&bs->quiesce_counter) > 0
+ */
+ assert(qemu_in_main_thread());
+}
+
/**
* Remove an active request from the tracked requests list
*
--
2.27.0
- [PATCH v5 00/31] block layer: split block APIs in global state and I/O, Emanuele Giuseppe Esposito, 2021/11/24
- [PATCH v5 01/31] main-loop.h: introduce qemu_in_main_thread(), Emanuele Giuseppe Esposito, 2021/11/24
- [PATCH v5 04/31] include/sysemu/block-backend: split header into I/O and global state (GS) API, Emanuele Giuseppe Esposito, 2021/11/24
- [PATCH v5 05/31] block-backend: special comments for blk_set/get_perm due to fuse, Emanuele Giuseppe Esposito, 2021/11/24
- [PATCH v5 03/31] assertions for block global state API, Emanuele Giuseppe Esposito, 2021/11/24
- [PATCH v5 06/31] block/block-backend.c: assertions for block-backend, Emanuele Giuseppe Esposito, 2021/11/24
- [PATCH v5 02/31] include/block/block: split header into I/O and global state API, Emanuele Giuseppe Esposito, 2021/11/24
- [PATCH v5 10/31] block.c: modify .attach and .detach callbacks of child_of_bds, Emanuele Giuseppe Esposito, 2021/11/24
- [PATCH v5 08/31] assertions for block_int global state API, Emanuele Giuseppe Esposito, 2021/11/24
- [PATCH v5 09/31] block: introduce assert_bdrv_graph_writable,
Emanuele Giuseppe Esposito <=
- [PATCH v5 07/31] include/block/block_int: split header into I/O and global state API, Emanuele Giuseppe Esposito, 2021/11/24
- [PATCH v5 12/31] assertions for blockjob_int.h, Emanuele Giuseppe Esposito, 2021/11/24
- [PATCH v5 13/31] block.c: add assertions to static functions, Emanuele Giuseppe Esposito, 2021/11/24
- [PATCH v5 11/31] include/block/blockjob_int.h: split header into I/O and GS API, Emanuele Giuseppe Esposito, 2021/11/24
- [PATCH v5 14/31] include/block/blockjob.h: global state API, Emanuele Giuseppe Esposito, 2021/11/24
- [PATCH v5 15/31] assertions for blockjob.h global state API, Emanuele Giuseppe Esposito, 2021/11/24
- [PATCH v5 17/31] assertions for blockdev.h global state API, Emanuele Giuseppe Esposito, 2021/11/24
- [PATCH v5 19/31] block/copy-before-write.h: global state API + assertions, Emanuele Giuseppe Esposito, 2021/11/24
- [PATCH v5 16/31] include/sysemu/blockdev.h: global state API, Emanuele Giuseppe Esposito, 2021/11/24
- [PATCH v5 18/31] include/block/snapshot: global state API + assertions, Emanuele Giuseppe Esposito, 2021/11/24