Commit 87ace5f8 authored by Max Reitz's avatar Max Reitz Committed by Kevin Wolf
Browse files

block: Fix order in bdrv_replace_child() 



We have to start by applying the permission restrictions to new_bs
before we can loosen them on old_bs.  See the comment for the
explanation.

Signed-off-by: default avatarMax Reitz <mreitz@redhat.com>
Reviewed-by: default avatarKevin Wolf <kwolf@redhat.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent a193ad3b

block.c

+13 −5
Original line number Diff line number Diff line
@@ -2240,6 +2240,19 @@ static void bdrv_replace_child(BdrvChild *child, BlockDriverState *new_bs) 


    bdrv_replace_child_noperm(child, new_bs);



    /*

     * Start with the new node's permissions.  If @new_bs is a (direct

     * or indirect) child of @old_bs, we must complete the permission

     * update on @new_bs before we loosen the restrictions on @old_bs.

     * Otherwise, bdrv_check_perm() on @old_bs would re-initiate

     * updating the permissions of @new_bs, and thus not purely loosen

     * restrictions.

     */

    if (new_bs) {

        bdrv_get_cumulative_perm(new_bs, &perm, &shared_perm);

        bdrv_set_perm(new_bs, perm, shared_perm);

    }



    if (old_bs) {

        /* Update permissions for old node. This is guaranteed to succeed

         * because we're just taking a parent away, so we're loosening
@@ -2252,11 +2265,6 @@ static void bdrv_replace_child(BdrvChild *child, BlockDriverState *new_bs) 
         * node moves back to the main AioContext */

        bdrv_try_set_aio_context(old_bs, qemu_get_aio_context(), NULL);

    }



    if (new_bs) {

        bdrv_get_cumulative_perm(new_bs, &perm, &shared_perm);

        bdrv_set_perm(new_bs, perm, shared_perm);

    }

}



/*