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    SubjectRe: [Patch 1/6] dm: endio method
    Hey Joe,

    Joe Thornber wrote:

    > Mike,
    >
    > On Sat, Feb 21, 2004 at 01:58:38AM -0800, Mike Christie wrote:
    >
    >>Saving and restoring bi_bdev is going to break multipath.
    >
    >
    > Yes, we'll have to fall back to plan A and use the map_context pointer
    > to hold the path being used (attached patch for illustration only). I
    > had been hoping we could keep the map_context unused so that we could
    > allow the path selectors to use it. I should have spotted this.
    >
    > I'll also move the failed bio remap back to mpath_end_io(), so that
    > the context can be reused there (it moved to the daemon when we were
    > trying to do path testing in the kernel).
    >

    With this move if the path has to be activated first, will the daemon
    have to call some sort of ps_path_is_initialized() function before it
    calls generic_make_request?

    It might be easier if mp's map_io call did not move so it or the ps
    could send commands and wait for the response before selecting a path. I
    guess this would mean you would have to add a access function for the
    tio's map_info so it could be set from the daemon, or mp may need to
    allocate its own io wrapper. It seems the latter may now be needed to
    give ps's a a map_info, becuase dm-mpath needs to store the path in the
    tio's map_info.

    Mike
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