From e9238278c2272fd3c6a1d339303e3ee2a2e2fbd3 Mon Sep 17 00:00:00 2001 From: Vladimir Sementsov-Ogievskiy Date: Thu, 10 Jun 2021 15:05:30 +0300 Subject: [PATCH] block: introduce bdrv_set_file_or_backing_noperm() 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 Message-Id: <20210610120537.196183-3-vsementsov@virtuozzo.com> Signed-off-by: Kevin Wolf --- block.c | 83 +++++++++++++++++++++++++++++++++++++++++++++++++---------------- 1 file changed, 63 insertions(+), 20 deletions(-) diff --git a/block.c b/block.c index 7eceef0afa..14711ce7ab 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) { -- 2.11.4.GIT