Re: [PATCH] bcache: Possible flush fix

[Kent Overstreet <kmo-PEzghdH756F8UrSeD/g0lQ@public.gmane.org>]

On Wed, Sep 18, 2013 at 01:57:21PM +0000, Hubert Kempkensteffen wrote:
> Kent Overstreet <kmo@...> writes:
> 
> > 
> > Jens suggested that cloning the bio to issue a bare flush might be
> > copying some flags we don't want, and at least allocating a new bio
> > would be more correct. Worth a shot...
> > 
> > Signed-off-by: Kent Overstreet <kmo@...>
> > ---
> > 
> > On Tue, Sep 17, 2013 at 08:54:57PM +0000, Hubert Kempkensteffen wrote:
> > > Kent Overstreet <kmo <at> ...> writes:
> > > Sorry, my english.
> > > I have no raid and no LVM. There are both ordinary machines.
> > > And I just want to speed up the data disk!
> > > 
> > > > 
> > > > I think this bug requires something else in the stack to trigger, I'm
> > > > trying to figure out what the common factor is.
> > 
> > Can you give this patch a try?
> > 
> >  drivers/md/bcache/request.c | 20 +++++++++++---------
> >  1 file changed, 11 insertions(+), 9 deletions(-)
> > 
> > diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
> > index afb9a99..c06840b 100644
> > --- a/drivers/md/bcache/request.c
> > +++ b/drivers/md/bcache/request.c
> >  <at>  <at>  -1053,19 +1053,21  <at>  <at>  static void
> request_write(struct cached_dev *dc, struct search *s)
> >  		trace_bcache_writethrough(s->orig_bio);
> >  		closure_bio_submit(bio, cl, s->d);
> >  	} else {
> > +		s->op.cache_bio = bio;
> >  		trace_bcache_writeback(s->orig_bio);
> >  		bch_writeback_add(dc, bio_sectors(bio));
> > 
> > -		if (s->op.flush_journal) {
> > +		if (bio->bi_rw & REQ_FLUSH) {
> >  			/* Also need to send a flush to the backing device */
> > -			s->op.cache_bio = bio_clone_bioset(bio, GFP_NOIO,
> > -							   dc->disk.bio_split);
> > -
> > -			bio->bi_size = 0;
> > -			bio->bi_vcnt = 0;
> > -			closure_bio_submit(bio, cl, s->d);
> > -		} else {
> > -			s->op.cache_bio = bio;
> > +			struct bio *flush = bio_alloc_bioset(0, GFP_NOIO,
> > +							     dc->disk.bio_split);
> > +
> > +			flush->bi_rw	= WRITE_FLUSH;
> > +			flush->bi_bdev	= bio->bi_bdev;
> > +			flush->bi_end_io = request_endio;
> > +			flush->bi_private = cl;
> > +
> > +			closure_bio_submit(flush, cl, s->d);
> >  		}
> >  	}
> >  out:
> 
> I am currently testing the patch. (writethrough)
> The kernel is: git clone http://evilpiepirate.org/git/linux-bcache.git

What branch?