On 09/18/2016 11:37 PM, Denis V. Lunev wrote: > On 09/19/2016 04:21 AM, Fam Zheng wrote: >> On Thu, 09/15 19:34, Denis V. Lunev wrote: >>> They should work very similar, covering same areas if backing store is >>> shorter than the image. This change is necessary for the followup patch >>> switching to bdrv_get_block_status_above() in mirror to avoid assert >>> in check_block. >>> >>> This change should be made very carefully. Let us assume that we have >>> top image and 2 backing stores L0->L1->L2. >> Stupid question: which one is top and which are backing? > L0 is top, L2 is at bottom.
I typically write this as: L2 <- L1 <- L0 (read "L2 backs L1, which in turn backs L0") with the active on the right. So I understand the confusion in Fam's question where you were using the opposite direction. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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