tree a1e53e2369d7b92f71e951d8c9bb23237642e39f
parent d42a8a935b8b2d567331fffa13a70918352668bb
author Kevin Wolf <kwolf@redhat.com> 1434629397 +0200
committer Kevin Wolf <kwolf@redhat.com> 1445002470 +0200

block: Implement bdrv_append() without bdrv_swap()

Remember all parent nodes and just change the pointers there instead of
swapping the contents of the BlockDriverState.

Handling of snapshot=on must be moved further down in bdrv_open()
because *pbs (which is the bs pointer in the BlockBackend) must already
be set before bdrv_append() is called. Otherwise bdrv_append() changes
the BB's pointer to the temporary snapshot, but bdrv_open() overwrites
it with the read-only original image.

We also need to be careful to update callers as the interface changes
(becomes less insane): Previously, the meaning of the two parameters was
inverted when bdrv_append() returns. Now any BDS pointers keep pointing
to the same node.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>