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由 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>
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