• J
    block: set device_list.tqe_prev to NULL on BDS removal · f8aa905a
    Jeff Cody 提交于
    This fixes a regression introduced with commit 3f09bfbc.  Multiple
    bugs arise in conjunction with live snapshots and mirroring operations
    (which include active layer commit).
    
    After a live snapshot occurs, the active layer and the base layer both
    have a non-NULL tqe_prev field in the device_list, although the base
    node's tqe_prev field points to a NULL entry.  This non-NULL tqe_prev
    field occurs after the bdrv_append() in the external snapshot calls
    change_parent_backing_link().
    
    In change_parent_backing_link(), when the previous active layer is
    removed from device_list, the device_list.tqe_prev pointer is not
    set to NULL.
    
    The operating scheme in the block layer is to indicate that a BDS belongs
    in the bdrv_states device_list iff the device_list.tqe_prev pointer
    is non-NULL.
    
    This patch does two things:
    
    1.) Introduces a new block layer helper bdrv_device_remove() to remove a
        BDS from the device_list, and
    2.) uses that new API, which also fixes the regression once used in
        change_parent_backing_link().
    Signed-off-by: NJeff Cody <jcody@redhat.com>
    Message-id: 0cd51e11c0666c04ddb7c05293fe94afeb551e89.1454376655.git.jcody@redhat.com
    Reviewed-by: NMax Reitz <mreitz@redhat.com>
    Signed-off-by: NMax Reitz <mreitz@redhat.com>
    f8aa905a
block.c 124.4 KB