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    SubjectRe: [patch] scsi: revert "[SCSI] Get rid of scsi_cmnd->done"
    On Sun, Jan 06 2008 at 5:43 +0200, Linus Torvalds <torvalds@linux-foundation.org> wrote:
    >
    >
    > This all still leaves the question unanswered why that commit
    > 6f5391c283d7fdcf24bf40786ea79061919d1e1d changed any behaviour at all.
    > Because the thing that Peter is describing has nothing to do with any
    > low-level drivers what-so-ever.
    >
    > Linus
    >

    James Matthew.
    I have a (very) wild guess at what maybe have changed with the cmnd->done
    patch:

    Do you remember the effective loop in scsi_lib:scsi_end_request() where
    if bufflen was smaller then original request size, do to truncation
    of bufflen by ULD, then the remaining of the request is re-queued again
    as a new scsi-command. Well I think that the old system would call
    cmnd->done for every iteration, and the new system, since the done is
    called by the block-Q, does not see the resubmit of the new command.

    I have not followed all code path of the matter, but I know that sr does
    alters bufflen in some cases.
    All this is not a bug in itself, but it is a change in behavior that might
    cause the current sr hack to fail.

    Boaz


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