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[PATCH] fix blk_direct_IO bio preparation

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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>
This commit is contained in:
Chen, Kenneth W 2007-01-22 20:40:43 -08:00 committed by Linus Torvalds
parent 15c945c3d0
commit cda9205da2
1 changed files with 8 additions and 0 deletions
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8
fs/block_dev.c
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@ -190,6 +190,12 @@ static struct page *blk_get_page(unsigned long addr, size_t count, int rw,
return pvec->page[pvec->idx++];
}
/* return a page back to pvec array */
static void blk_unget_page(struct page *page, struct pvec *pvec)
{
pvec->page[--pvec->idx] = page;
}
static ssize_t
blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
loff_t pos, unsigned long nr_segs)
@ -278,6 +284,8 @@ blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
count = min(count, nbytes);
goto same_bio;
}
} else {
blk_unget_page(page, &pvec);
}
/* bio is ready, submit it */