<linux/device-mapper.h> duplicates a list of fields in struct
request_queue. I've wanted to get those fields into a separate
structure to make it easier for drivers to manipulate them as a group
without having to be modified as often when those fields change.
I imagine that most block device drivers would simply declare a
struct io_restrictions that they would copy in its entirety into
the struct request_queue's that they initialize.
This change will also eventually make it easier to lift the
mergability tests out of the block layer and apply it to
gather-scatter DMA in general, although that will probabably entail
some minor changes to struct io_restrictions, like counting entirely
in bytes instead of sectors. (However you don't have to buy into this
larger vision to be in favor of this patch.)
Here are the header file changes (haven't even tried to
compile it), a net deletion of four lines. If this change seems
reasonable, I'll edit the rest of the C files, make it compile and run
and submit a real patch that should compile to the same object code as
before. Please let me know if this is OK.
--
Adam J. Richter __ ______________ 575 Oroville Road
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