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    SubjectRe: Possibly wrong BIO usage in ide_multwrite
    On Sunday 04 of January 2004 18:30, Christophe Saout wrote:
    > Am Sa, den 03.01.2004 schrieb Bartlomiej Zolnierkiewicz um 23:02:
    > > > The way I would prefer is that when someone calls bio_endio the bi_idx
    > > > and bv_offset just point where the processed data begins.
    > >
    > > Are you aware that this will make partial completions illegal?
    > > [ No problem for me. ]
    > Why that? __end_that_request_first already does this (when moving thw
    > two lines updating bv_offset/bv_len after the call of the bi_end_io
    > function).

    Looking once again, I see it is OK.

    > > > Can't another (some local) variable be used as bvec index instead of
    > > > bi_idx in the original bio? (except from ide_map_buffer using exactly
    > > > this index...)
    > >
    > > see rq_map_buffer() in include/linux/blkdev.h
    > Right. I've been going through ide-taskfile.c for the last hours.
    > The IDE_TASKFILE_IO gets things right (from my point of view) and is
    > also much cleaner. (I would personally vote for dropping the non
    > TASKFILE_IO code, it would make my problem go away :D - why is it still
    > marked as experimental BTW? I've been using it since it was introduced,
    > without any problems)

    There are still some issues to be resolved:
    - hangs during reading /proc/ide/<cdrom>/identify on some drives
    (workaround is now known thanks to debugging done by Andi+BenH+Andre)
    - unexplained fs corruption on x86-64 with AMD IDE chipsets
    (the real showstopper)
    - somebody needs to test taskfile code on old Promise PDC4030 controller
    (low priority)

    > BTW: The taskfile code that is used when IDE_TASKFILE_IO is disabled
    > might partially end requests without knowing the actual status, right?


    > So non TASKFILE_IO code has two multout codepaths (taskfile and not)
    > that are both "awkward" while TASKFILE_IO merges both into a single and
    > clean version.


    > > > Would you be interested in a small patch (well, if I can come up with
    > > > one)?
    > >
    > > Sure, but I don't know what you want to change... :-)
    > I'm not yet sure, either. I don't think that a too invasive version
    > would be adequate though converting this mess to the cbio method would
    > be nice. Or would you prefer to see that? I don't think it's worth
    > starting on that since you said you'de like to see this part of the IDE
    > layer die in 2.7 anyway. I would really like to see ide_map_buffer die
    > in favor of rq_map_buffer though. Hmm.
    > Perhaps I can think of something else. It's really tricky...

    I would like to remove non CONFIG_IDE_TASKFILE_IO paths in 2.6.x
    (after issues are resolved) instead of trying to fix them.


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