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[PATCH v2 02/10] block: Manipulate children list in .attach/.detach
From: |
Hanna Reitz |
Subject: |
[PATCH v2 02/10] block: Manipulate children list in .attach/.detach |
Date: |
Thu, 11 Nov 2021 13:08:21 +0100 |
The children list is specific to BDS parents. We should not modify it
in the general children modification code, but let BDS parents deal with
it in their .attach() and .detach() methods.
This also has the advantage that a BdrvChild is removed from the
children list before its .bs pointer can become NULL. BDS parents
generally assume that their children's .bs pointer is never NULL, so
this is actually a bug fix.
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
block.c | 14 +++++---------
1 file changed, 5 insertions(+), 9 deletions(-)
diff --git a/block.c b/block.c
index 580cb77a70..ca024ffced 100644
--- a/block.c
+++ b/block.c
@@ -1387,6 +1387,8 @@ static void bdrv_child_cb_attach(BdrvChild *child)
{
BlockDriverState *bs = child->opaque;
+ QLIST_INSERT_HEAD(&bs->children, child, next);
+
if (child->role & BDRV_CHILD_COW) {
bdrv_backing_attach(child);
}
@@ -1403,6 +1405,8 @@ static void bdrv_child_cb_detach(BdrvChild *child)
}
bdrv_unapply_subtree_drain(child, bs);
+
+ QLIST_REMOVE(child, next);
}
static int bdrv_child_cb_update_filename(BdrvChild *c, BlockDriverState *base,
@@ -2747,7 +2751,7 @@ static void bdrv_child_free(void *opaque)
static void bdrv_remove_empty_child(BdrvChild *child)
{
assert(!child->bs);
- QLIST_SAFE_REMOVE(child, next);
+ assert(!child->next.le_prev); /* not in children list */
bdrv_child_free(child);
}
@@ -2913,12 +2917,6 @@ static int bdrv_attach_child_noperm(BlockDriverState
*parent_bs,
return ret;
}
- QLIST_INSERT_HEAD(&parent_bs->children, *child, next);
- /*
- * child is removed in bdrv_attach_child_common_abort(), so don't care to
- * abort this change separately.
- */
-
return 0;
}
@@ -4851,7 +4849,6 @@ static void bdrv_remove_filter_or_cow_child_abort(void
*opaque)
BdrvRemoveFilterOrCowChild *s = opaque;
BlockDriverState *parent_bs = s->child->opaque;
- QLIST_INSERT_HEAD(&parent_bs->children, s->child, next);
if (s->is_backing) {
parent_bs->backing = s->child;
} else {
@@ -4906,7 +4903,6 @@ static void
bdrv_remove_file_or_backing_child(BlockDriverState *bs,
};
tran_add(tran, &bdrv_remove_filter_or_cow_child_drv, s);
- QLIST_SAFE_REMOVE(child, next);
if (s->is_backing) {
bs->backing = NULL;
} else {
--
2.33.1
- [PATCH v2 00/10] block: Attempt on fixing 030-reported errors, Hanna Reitz, 2021/11/11
- [PATCH v2 01/10] stream: Traverse graph after modification, Hanna Reitz, 2021/11/11
- [PATCH v2 02/10] block: Manipulate children list in .attach/.detach,
Hanna Reitz <=
- [PATCH v2 04/10] block: Drop detached child from ignore list, Hanna Reitz, 2021/11/11
- [PATCH v2 03/10] block: Unite remove_empty_child and child_free, Hanna Reitz, 2021/11/11
- [PATCH v2 05/10] block: Pass BdrvChild ** to replace_child_noperm, Hanna Reitz, 2021/11/11
- [PATCH v2 06/10] block: Restructure remove_file_or_backing_child(), Hanna Reitz, 2021/11/11
- [PATCH v2 08/10] block: Let replace_child_tran keep indirect pointer, Hanna Reitz, 2021/11/11
- [PATCH v2 07/10] transactions: Invoke clean() after everything else, Hanna Reitz, 2021/11/11