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    SubjectRe: [patch] block device stacking support, raid-2.3.47-B6

    On Wed, 23 Feb 2000, Andrea Arcangeli wrote:

    > >- renaming ->make_request_fn() to ->logical_volume_fn is both misleading
    > > and unnecessery.
    >
    > Note that with my proposal it was make_request_fn to be misleading because
    > all the code run within the callback had anything to do with the
    > make_request code.

    ok, your variant was more like a ->map_buffer_fn() thing - like the old
    md_map() stuff. ->make_request_fn() is closer to 'make request' in the
    context of RAID1 and RAID5. (even if this is not visible now).

    > > - device resolves recursion internally and returns 0 (future RAID0),
    > > returns 1 if recursion cannot be resolved internally.
    >
    > I don't think it worth to handle such case if it costs something for the
    > other cases. I'll check and test the code on the LVM side soon.

    the cost is only in the device (not in the generic block IO code), it's a
    'if (MAJOR(bh->b_rdev) == MD_MAJOR) goto repeat;' type of thing (analogous
    in the LVM code), nothing more. We will see how common it gets - it's just
    a nice side-effect that th possibility is there.

    Ingo


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