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    SubjectRe: [PATCH v2 0/7] convert most filesystems to pin_user_pages_fast()
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    On 9/6/22 00:22, Christoph Hellwig wrote:
    > On Tue, Sep 06, 2022 at 12:10:54AM -0700, John Hubbard wrote:
    >> I would be delighted if that were somehow possible. Every time I think
    >> it's possible, it has fallen apart. The fact that bio_release_pages()
    >> will need to switch over from put_page() to unpin_user_page(), combined
    >> with the fact that there are a lot of callers that submit bios, has
    >> led me to the current approach.
    >
    > We can (temporarily) pass the gup flag to bio_release_pages or even
    > better add a new bio_unpin_pages helper that undoes the pin side.
    > That is: don't try to reuse the old APIs, but ad new ones, just like
    > we do on the lower layers.

    OK...so, to confirm: the idea is to convert these callsites (below) to
    call a new bio_unpin_pages() routine that does unpin_user_page().

    $ git grep -nw bio_release_pages
    block/bio.c:1474: bio_release_pages(bio, true);
    block/bio.c:1490: bio_release_pages(bio, false);
    block/blk-map.c:308: bio_release_pages(bio, false);
    block/blk-map.c:610: bio_release_pages(bio, bio_data_dir(bio) == READ);
    block/fops.c:99: bio_release_pages(&bio, should_dirty);
    block/fops.c:165: bio_release_pages(bio, false);
    block/fops.c:289: bio_release_pages(bio, false);
    fs/direct-io.c:510: bio_release_pages(bio, should_dirty);
    fs/iomap/direct-io.c:185: bio_release_pages(bio, false);
    fs/zonefs/super.c:793: bio_release_pages(bio, false);


    And these can probably be done in groups, not as one big patch--your
    other email also asked to break them up into block, iomap, and legacy.

    That would be nice, I really hate the ugly dio_w*() wrappers, thanks
    for this help. :)

    thanks,

    --
    John Hubbard
    NVIDIA

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