Messages in this thread | | | Date | Thu, 11 Jan 2007 13:44:59 -0800 | From | Randy Dunlap <> | Subject | Re: [patch] optimize o_direct on block device - v3 |
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On Thu, 11 Jan 2007 13:36:28 -0800 Chen, Kenneth W wrote:
> Andrew Morton wrote on Thursday, January 11, 2007 11:29 AM > > On Thu, 11 Jan 2007 13:21:57 -0600 > > Michael Reed <mdr@sgi.com> wrote: > > > Testing on my ia64 system reveals that this patch introduces a > > > data integrity error for direct i/o to a block device. Device > > > errors which result in i/o failure do not propagate to the > > > process issuing direct i/o to the device. > > > > > > This can be reproduced by doing writes to a fibre channel block > > > device and then disabling the switch port connecting the host > > > adapter to the switch. > > > > > > > Does this fix it? > > > > <thwaps Ken> > > > Darn, kicking myself in the butt. Thank you Andrew for fixing this. > We've also running DIO stress test almost non-stop over the last 30 > days or so and we did uncover another bug in that patch. > > Andrew, would you please take the follow bug fix patch as well. It > is critical because it also affects data integrity. > > > [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 forget 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> > > diff -Nurp linux-2.6.20-rc4/fs/block_dev.c linux-2.6.20.ken/fs/block_dev.c > --- linux-2.6.20-rc4/fs/block_dev.c 2007-01-06 21:45:51.000000000 -0800 > +++ linux-2.6.20.ken/fs/block_dev.c 2007-01-10 19:54:53.000000000 -0800 > @@ -190,6 +190,12 @@ static struct page *blk_get_page(unsigne > return pvec->page[pvec->idx++]; > } > > +/* return a pge back to pvec array */
is pge just a typo or some other tla that i don't know? (not portland general electric or pacific gas & electric)
> +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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