Re: [PATCH 5/6] IB core: Fix ib_sg_to_pages()

[Sagi Grimberg <sagig-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>]

Hi Bart,

> Fix the code for detecting gaps and disable the code for chunking.
> A gap occurs not only if the second or later scatterlist element
> is not aligned but also if any scatterlist element other than the
> last does not end at a page boundary. Disable the code for chunking.

So can you explain what went wrong with the code? If ib_sg_to_pages()
supports chunking, then sg elements are allowed not to end at a page
boundary if it is physically contig to the next sg and then the next
is chunked. Care to explain how did ib_sg_to_pages mess up?

> Ensure that this function returns a negative error code instead of
> zero if the first set_page() call fails.

Umm, my recollection was to make ib_map_mr_sg return the largest prefix
mapped. I don't mind a negative error in this case, but isn't zero an
implicit error (given you didn't want to map 0 sg elements)?

If we do agree on this we need to change ib_map_mr_sg documentation
accordingly.
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