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block: Add BlockDriverState.inherits_from

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Currently, the block layer assumes that any block node can have only one
parent, and if it has a parent, that it inherits some options/flags from
this parent.

This is not true any more: With references used in block device
creation, a single node can be used by multiple parents, or it can be
created separately and not inherit flags from any parent.

To handle reopens correctly, a node must know from which parent it
inherited options. This patch adds the information to BlockDriverState.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Kevin Wolf 2015-04-09 18:47:50 +02:00
parent 6e93e7c41f
commit bddcec3745
2 changed files with 21 additions and 0 deletions
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17
block.c
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@ -1409,6 +1409,7 @@ static int bdrv_open_inherit(BlockDriverState **pbs, const char *filename,
}
if (child_role) {
bs->inherits_from = parent;
flags = child_role->inherit_flags(parent->open_flags);
}
@ -1837,6 +1838,9 @@ void bdrv_close(BlockDriverState *bs)
BdrvChild *child, *next;
QLIST_FOREACH_SAFE(child, &bs->children, next, next) {
if (child->bs->inherits_from == bs) {
child->bs->inherits_from = NULL;
}
QLIST_REMOVE(child, next);
g_free(child);
}
@ -1985,6 +1989,7 @@ static void bdrv_move_feature_fields(BlockDriverState *bs_dest,
void bdrv_swap(BlockDriverState *bs_new, BlockDriverState *bs_old)
{
BlockDriverState tmp;
BdrvChild *child;
bdrv_drain(bs_new);
bdrv_drain(bs_old);
@ -2044,6 +2049,18 @@ void bdrv_swap(BlockDriverState *bs_new, BlockDriverState *bs_old)
QLIST_FIX_HEAD_PTR(&bs_new->children, next);
QLIST_FIX_HEAD_PTR(&bs_old->children, next);
/* Update references in bs->opaque and children */
QLIST_FOREACH(child, &bs_old->children, next) {
if (child->bs->inherits_from == bs_new) {
child->bs->inherits_from = bs_old;
}
}
QLIST_FOREACH(child, &bs_new->children, next) {
if (child->bs->inherits_from == bs_old) {
child->bs->inherits_from = bs_new;
}
}
bdrv_rebind(bs_new);
bdrv_rebind(bs_old);
}

4
include/block/block_int.h
View File

@ -437,6 +437,10 @@ struct BlockDriverState {
/* long-running background operation */
BlockJob *job;
/* The node that this node inherited default options from (and a reopen on
* which can affect this node by changing these defaults). This is always a
* parent node of this node. */
BlockDriverState *inherits_from;
QLIST_HEAD(, BdrvChild) children;
QDict *options;