Messages in this thread | | | Date | Thu, 25 May 2023 02:51:59 -0700 | From | Christoph Hellwig <> | Subject | Re: Extending page pinning into fs/direct-io.c |
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On Wed, May 24, 2023 at 09:47:10AM +0100, David Howells wrote: > True - but I was thinking of just treating the zero_page specially and never > hold a pin or a ref on it. It can be checked by address, e.g.: > > static inline void bio_release_page(struct bio *bio, struct page *page) > { > if (page == ZERO_PAGE(0)) > return; > if (bio_flagged(bio, BIO_PAGE_PINNED)) > unpin_user_page(page); > else if (bio_flagged(bio, BIO_PAGE_REFFED)) > put_page(page); > }
That does sound good as well to me.
> I was looking at this: > > static inline void dio_bio_submit(struct dio *dio, struct dio_submit *sdio) > { > ... > if (dio->is_async && dio_op == REQ_OP_READ && dio->should_dirty) > bio_set_pages_dirty(bio); > ... > } > > but looking again, the lock is taken briefly and the dirty bit is set - which > is reasonable. However, should we be doing it before starting the I/O?
It is done before starting the I/O - the submit_bio is just below this.
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