Commit cda9205d authored Jan 22, 2007 by Chen, Kenneth W Committed by Linus Torvalds Jan 23, 2007

[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>

parent 15c945c3

fs/block_dev.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -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 @@ same_bio:
		count = min(count, nbytes);
		goto same_bio;
		}
		} else {
		blk_unget_page(page, &pvec);
		}

		/* bio is ready, submit it */

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