Re: [Libguestfs] [PATCH nbdkit 7/8] vddk: Implement extents.

>> This inner loop might be long; you could add this: >> >> if (req_one) >> break; So interestingly _no_ you can't add that here, and the reason does reveal why the REQ_ONE flag is still hard to get right even with the simpler implementation of extents. Because VDDK's QueryAllocatedBlocks API only works for some very large aligned block size (64K IIRC), we round down the requested offset before querying VDDK. So in the inner loop the first extent we get back might lie before the offset (before extents->start). IOW nbdkit_add_extent has succeeded but we haven't added any extents. We could call nbdkit_extents_count here, but technically we've said that's a filter-only API.

I believe the test for req_one in the outer loop is fine, although it relies on QueryAllocatedBlocks not being crazy. As it's VDDK and therefore crazy by nature

maybe we should consider removing that too, but it would then be really inefficient ...