From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
To: qemu-block@nongnu.org
Cc: qemu-devel@nongnu.org, mreitz@redhat.com, kwolf@redhat.com,
berto@igalia.com, vsementsov@virtuozzo.com
Subject: [PATCH v6 2/9] block: introduce bdrv_set_file_or_backing_noperm()
Date: Thu, 10 Jun 2021 15:05:30 +0300 [thread overview]
Message-ID: <20210610120537.196183-3-vsementsov@virtuozzo.com> (raw)
In-Reply-To: <20210610120537.196183-1-vsementsov@virtuozzo.com>
To be used for reopen in future commit.
Notes:
- It seems OK to update inherits_from if new bs is recursively inherits
from parent bs. Let's just not check for backing_chain_contains, to
support file child of non-filters.
- Simply check child->frozen instead of
bdrv_is_backing_chain_frozen(), as we really interested only in this
one child.
- Role determination of new child is a bit more complex: it remains
the same for backing child, it's obvious for filter driver. But for
non-filter file child let's for now restrict to only replacing
existing child (and keeping its role).
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
block.c | 83 +++++++++++++++++++++++++++++++++++++++++++--------------
1 file changed, 63 insertions(+), 20 deletions(-)
diff --git a/block.c b/block.c
index d21c9e4316..89c61fe93d 100644
--- a/block.c
+++ b/block.c
@@ -84,6 +84,9 @@ static BlockDriverState *bdrv_open_inherit(const char *filename,
static void bdrv_replace_child_noperm(BdrvChild *child,
BlockDriverState *new_bs);
+static void bdrv_remove_file_or_backing_child(BlockDriverState *bs,
+ BdrvChild *child,
+ Transaction *tran);
static void bdrv_remove_filter_or_cow_child(BlockDriverState *bs,
Transaction *tran);
@@ -3117,56 +3120,96 @@ static BdrvChildRole bdrv_backing_role(BlockDriverState *bs)
}
/*
- * Sets the bs->backing link of a BDS. A new reference is created; callers
- * which don't need their own reference any more must call bdrv_unref().
+ * Sets the bs->backing or bs->file link of a BDS. A new reference is created;
+ * callers which don't need their own reference any more must call bdrv_unref().
*
* Function doesn't update permissions, caller is responsible for this.
*/
-static int bdrv_set_backing_noperm(BlockDriverState *bs,
- BlockDriverState *backing_hd,
- Transaction *tran, Error **errp)
+static int bdrv_set_file_or_backing_noperm(BlockDriverState *parent_bs,
+ BlockDriverState *child_bs,
+ bool is_backing,
+ Transaction *tran, Error **errp)
{
int ret = 0;
- bool update_inherits_from = bdrv_chain_contains(bs, backing_hd) &&
- bdrv_inherits_from_recursive(backing_hd, bs);
+ bool update_inherits_from =
+ bdrv_inherits_from_recursive(child_bs, parent_bs);
+ BdrvChild *child = is_backing ? parent_bs->backing : parent_bs->file;
+ BdrvChildRole role;
- if (bdrv_is_backing_chain_frozen(bs, child_bs(bs->backing), errp)) {
+ if (!parent_bs->drv) {
+ /*
+ * Node without drv is an object without a class :/. TODO: finally fix
+ * qcow2 driver to never clear bs->drv and implement format corruption
+ * handling in other way.
+ */
+ error_setg(errp, "Node corrupted");
+ return -EINVAL;
+ }
+
+ if (child && child->frozen) {
+ error_setg(errp, "Cannot change frozen '%s' link from '%s' to '%s'",
+ child->name, parent_bs->node_name, child->bs->node_name);
return -EPERM;
}
- if (bs->backing) {
- /* Cannot be frozen, we checked that above */
- bdrv_unset_inherits_from(bs, bs->backing, tran);
- bdrv_remove_filter_or_cow_child(bs, tran);
+ if (parent_bs->drv->is_filter) {
+ role = BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY;
+ } else if (is_backing) {
+ role = BDRV_CHILD_COW;
+ } else {
+ /*
+ * We only can use same role as it is in existing child. We don't have
+ * infrastructure to determine role of file child in generic way
+ */
+ if (!child) {
+ error_setg(errp, "Cannot set file child to format node without "
+ "file child");
+ return -EINVAL;
+ }
+ role = child->role;
}
- if (!backing_hd) {
+ if (child) {
+ bdrv_unset_inherits_from(parent_bs, child, tran);
+ bdrv_remove_file_or_backing_child(parent_bs, child, tran);
+ }
+
+ if (!child_bs) {
goto out;
}
- ret = bdrv_attach_child_noperm(bs, backing_hd, "backing",
- &child_of_bds, bdrv_backing_role(bs),
- &bs->backing, tran, errp);
+ ret = bdrv_attach_child_noperm(parent_bs, child_bs,
+ is_backing ? "backing" : "file",
+ &child_of_bds, role,
+ is_backing ? &parent_bs->backing :
+ &parent_bs->file,
+ tran, errp);
if (ret < 0) {
return ret;
}
/*
- * If backing_hd was already part of bs's backing chain, and
- * inherits_from pointed recursively to bs then let's update it to
+ * If inherits_from pointed recursively to bs then let's update it to
* point directly to bs (else it will become NULL).
*/
if (update_inherits_from) {
- bdrv_set_inherits_from(backing_hd, bs, tran);
+ bdrv_set_inherits_from(child_bs, parent_bs, tran);
}
out:
- bdrv_refresh_limits(bs, tran, NULL);
+ bdrv_refresh_limits(parent_bs, tran, NULL);
return 0;
}
+static int bdrv_set_backing_noperm(BlockDriverState *bs,
+ BlockDriverState *backing_hd,
+ Transaction *tran, Error **errp)
+{
+ return bdrv_set_file_or_backing_noperm(bs, backing_hd, true, tran, errp);
+}
+
int bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd,
Error **errp)
{
--
2.29.2
next prev parent reply other threads:[~2021-06-10 12:07 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-10 12:05 [PATCH v6 0/9] Allow changing bs->file on reopen Vladimir Sementsov-Ogievskiy
2021-06-10 12:05 ` [PATCH v6 1/9] block: introduce bdrv_remove_file_or_backing_child() Vladimir Sementsov-Ogievskiy
2021-06-10 12:05 ` Vladimir Sementsov-Ogievskiy [this message]
2021-06-10 12:05 ` [PATCH v6 3/9] block: bdrv_reopen_parse_backing(): don't check aio context Vladimir Sementsov-Ogievskiy
2021-06-10 12:05 ` [PATCH v6 4/9] block: bdrv_reopen_parse_backing(): don't check frozen child Vladimir Sementsov-Ogievskiy
2021-06-10 12:05 ` [PATCH v6 5/9] block: bdrv_reopen_parse_backing(): simplify handling implicit filters Vladimir Sementsov-Ogievskiy
2021-06-10 12:05 ` [PATCH v6 6/9] block: move supports_backing check to bdrv_set_file_or_backing_noperm() Vladimir Sementsov-Ogievskiy
2021-06-10 12:05 ` [PATCH v6 7/9] block: BDRVReopenState: drop replace_backing_bs field Vladimir Sementsov-Ogievskiy
2021-06-10 12:05 ` [PATCH v6 8/9] block: Allow changing bs->file on reopen Vladimir Sementsov-Ogievskiy
2021-06-10 12:05 ` [PATCH v6 9/9] iotests: Test replacing files with x-blockdev-reopen Vladimir Sementsov-Ogievskiy
2021-06-28 15:39 ` [PATCH v6 0/9] Allow changing bs->file on reopen Kevin Wolf
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