From 4e4bf5c42c8b2847a90367936a6df6c277f4a76a Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Fri, 16 Dec 2016 18:52:37 +0100 Subject: block: Attach bs->file only during .bdrv_open() The way that attaching bs->file worked was a bit unusual in that it was the only child that would be attached to a node which is not opened yet. Because of this, the block layer couldn't know yet which permissions the driver would eventually need. This patch moves the point where bs->file is attached to the beginning of the individual .bdrv_open() implementations, so drivers already know what they are going to do with the child. This is also more consistent with how driver-specific children work. For a moment, bdrv_open() gets its own BdrvChild to perform image probing, but instead of directly assigning this BdrvChild to the BDS, it becomes a temporary one and the node name is passed as an option to the drivers, so that they can simply use bdrv_open_child() to create another reference for their own use. This duplicated child for (the not opened yet) bs is not the final state, a follow-up patch will change the image probing code to use a BlockBackend, which is completely independent of bs. Signed-off-by: Kevin Wolf Reviewed-by: Max Reitz --- block/dmg.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'block/dmg.c') diff --git a/block/dmg.c b/block/dmg.c index 58a3ae86c1..8e387cdfe5 100644 --- a/block/dmg.c +++ b/block/dmg.c @@ -413,6 +413,12 @@ static int dmg_open(BlockDriverState *bs, QDict *options, int flags, int64_t offset; int ret; + bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file, + false, errp); + if (!bs->file) { + return -EINVAL; + } + block_module_load_one("dmg-bz2"); bs->read_only = true; -- cgit v1.2.3