Messages in this thread | | | From | Jeff Moyer <> | Subject | Re: [RFC PATCH] fs/direct-io.c: Set bi_rw when alloc bio. | Date | Fri, 27 Jul 2012 10:21:58 -0400 |
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majianpeng <majianpeng@gmail.com> writes:
> When exec bio_alloc, the bi_rw is zero.But after calling bio_add_page, > it will use bi_rw. > Fox example, in functiion __bio_add_page,it will call merge_bvec_fn(). > The merge_bvec_fn of raid456 will use the bi_rw to judge the merge. >>> if ((bvm->bi_rw & 1) == WRITE) >>> return biovec->bv_len; /* always allow writes to be mergeable */ > > Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>
Good catch. How did you find this? Did you experience data corruption as a result of this oversight, reduced performance due to missed merge opportunities, or did you just notice it in reviewing the code?
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
> > There are many place like this in kernel.If you think this patch ok, i will correct those. > --- > fs/direct-io.c | 1 + > 1 files changed, 1 insertions(+), 0 deletions(-) > > diff --git a/fs/direct-io.c b/fs/direct-io.c > index 1faf4cb..77f0bbf 100644 > --- a/fs/direct-io.c > +++ b/fs/direct-io.c > @@ -349,6 +349,7 @@ dio_bio_alloc(struct dio *dio, struct dio_submit *sdio, > > bio->bi_bdev = bdev; > bio->bi_sector = first_sector; > + bio->bi_rw = dio->rw; > if (dio->is_async) > bio->bi_end_io = dio_bio_end_aio; > else
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