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block: add bdrv_set_backing_noperm() transaction action

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Split out no-perm part of bdrv_set_backing_hd() as a separate
transaction action. Note the in case of existing BdrvChild we reuse it,
not recreate, just to do less actions.

We don't need to create extra reference to backing_hd as we don't lose
it in bdrv_attach_child().

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20210428151804.439460-29-vsementsov@virtuozzo.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Vladimir Sementsov-Ogievskiy 2021-04-28 18:17:56 +03:00 committed by Kevin Wolf
parent 1e4c797c75
commit 160333e1fe
1 changed files with 37 additions and 17 deletions
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54
block.c
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@ -92,6 +92,8 @@ static int bdrv_attach_child_noperm(BlockDriverState *parent_bs,
BdrvChild **child,
Transaction *tran,
Error **errp);
static void bdrv_remove_filter_or_cow_child(BlockDriverState *bs,
Transaction *tran);
static int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue
*queue, Error **errp);
@ -3322,8 +3324,9 @@ 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().
*/
int bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd,
Error **errp)
static int bdrv_set_backing_noperm(BlockDriverState *bs,
BlockDriverState *backing_hd,
Transaction *tran, Error **errp)
{
int ret = 0;
bool update_inherits_from = bdrv_chain_contains(bs, backing_hd) &&
@ -3333,36 +3336,53 @@ int bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd,
return -EPERM;
}
if (backing_hd) {
bdrv_ref(backing_hd);
}
if (bs->backing) {
/* Cannot be frozen, we checked that above */
bdrv_unref_child(bs, bs->backing);
bs->backing = NULL;
bdrv_unset_inherits_from(bs, bs->backing, tran);
bdrv_remove_filter_or_cow_child(bs, tran);
}
if (!backing_hd) {
goto out;
}
bs->backing = bdrv_attach_child(bs, backing_hd, "backing", &child_of_bds,
bdrv_backing_role(bs), errp);
if (!bs->backing) {
ret = -EPERM;
goto out;
ret = bdrv_attach_child_noperm(bs, backing_hd, "backing",
&child_of_bds, bdrv_backing_role(bs),
&bs->backing, tran, errp);
if (ret < 0) {
return ret;
}
/* If backing_hd was already part of bs's backing chain, and
/*
* If backing_hd was already part of bs's backing chain, and
* inherits_from pointed recursively to bs then let's update it to
* point directly to bs (else it will become NULL). */
* point directly to bs (else it will become NULL).
*/
if (update_inherits_from) {
backing_hd->inherits_from = bs;
bdrv_set_inherits_from(backing_hd, bs, tran);
}
out:
bdrv_refresh_limits(bs, NULL, NULL);
bdrv_refresh_limits(bs, tran, NULL);
return 0;
}
int bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd,
Error **errp)
{
int ret;
Transaction *tran = tran_new();
ret = bdrv_set_backing_noperm(bs, backing_hd, tran, errp);
if (ret < 0) {
goto out;
}
ret = bdrv_refresh_perms(bs, errp);
out:
tran_finalize(tran, ret);
return ret;
}