Am 19.09.2016 um 22:39 hat Eric Blake geschrieben: > 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.
And I tend to use this one:
base <- sn1 <- sn2 <- top
"sn*" isn't any better than "L*", but having at least one of "base" and
"top" (or "active") in there disambiguates the roles of the nodes.
Kevin
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