From 160333e1fef77ca6d4f7fde8f52bb0a944851104 Mon Sep 17 00:00:00 2001 From: Vladimir Sementsov-Ogievskiy Date: Wed, 28 Apr 2021 18:17:56 +0300 Subject: [PATCH] block: add bdrv_set_backing_noperm() transaction action 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 Reviewed-by: Kevin Wolf Message-Id: <20210428151804.439460-29-vsementsov@virtuozzo.com> Signed-off-by: Kevin Wolf --- block.c | 54 +++++++++++++++++++++++++++++++++++++----------------- 1 file changed, 37 insertions(+), 17 deletions(-) diff --git a/block.c b/block.c index 9922943793..bdfe59d94d 100644 --- a/block.c +++ b/block.c @@ -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; }