[PATCH] fix blk_direct_IO bio preparation
For large size DIO that needs multiple bio, one full page worth of data was lost at the boundary of bio's maximum sector or segment limits. After a bio is full and got submitted. The outer while (nbytes) { ... } loop will allocate a new bio and just march on to index into next page. It just forgets about the page that bio_add_page() rejected when previous bio is full. Fix it by put the rejected page back to pvec so we pick it up again for the next bio. Signed-off-by: Ken Chen <kenneth.w.chen@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -190,6 +190,12 @@ static struct page *blk_get_page(unsigned long addr, size_t count, int rw,
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return pvec->page[pvec->idx++];
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return pvec->page[pvec->idx++];
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}
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}
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/* return a page back to pvec array */
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static void blk_unget_page(struct page *page, struct pvec *pvec)
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{
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pvec->page[--pvec->idx] = page;
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}
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static ssize_t
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static ssize_t
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blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
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blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
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loff_t pos, unsigned long nr_segs)
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loff_t pos, unsigned long nr_segs)
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@ -278,6 +284,8 @@ same_bio:
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count = min(count, nbytes);
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count = min(count, nbytes);
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goto same_bio;
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goto same_bio;
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}
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}
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} else {
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blk_unget_page(page, &pvec);
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}
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}
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/* bio is ready, submit it */
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/* bio is ready, submit it */
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