From: Marcelo Tosatti <mtosa...@redhat.com> Close the now unused images that were part of the previous backing file chain and adjust ->backing_hd properly.
Note that this only works with relative paths. Given the images: /tmp/a/base.raw /tmp/a/snap1.qcow2 /tmp/b/snap2.qcow2 chained as: base(bak:"") <- snap1(bak:"base.raw") <- snap2(bak:"../a/snap1.qcow2") merging snap1 and snap2 we will obtain: base(bak:"") <- snap2(bak:"base.raw") However this should be maintained by the user/admin: one can also screw up relative paths using qemu-img manually. Signed-off-by: Marcelo Tosatti <mtosa...@redhat.com> Cc: Federico Simoncelli <fsimo...@redhat.com> Signed-off-by: Paolo Bonzini <pbonz...@redhat.com> --- block/stream.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/block/stream.c b/block/stream.c index 61ff7a2..54f2b39 100644 --- a/block/stream.c +++ b/block/stream.c @@ -76,6 +76,28 @@ static int coroutine_fn stream_populate(BlockDriverState *bs, return bdrv_co_copy_on_readv(bs, sector_num, nb_sectors, &qiov); } +static void close_unused_images(BlockDriverState *top, BlockDriverState *base, + const char *base_id) +{ + BlockDriverState *intermediate; + intermediate = top->backing_hd; + + while (intermediate) { + BlockDriverState *unused; + + /* reached base */ + if (intermediate == base) { + break; + } + + unused = intermediate; + intermediate = intermediate->backing_hd; + unused->backing_hd = NULL; + bdrv_delete(unused); + } + top->backing_hd = base; +} + /* * Given an image chain: [BASE] -> [INTER1] -> [INTER2] -> [TOP] * @@ -223,6 +245,7 @@ retry: base_id = s->backing_file_id; } ret = bdrv_change_backing_file(bs, base_id, NULL); + close_unused_images(bs, base, base_id); } qemu_vfree(buf); -- 1.7.9.3