On Mon, Sep 24, 2012 at 03:34:49PM -0700, Kent Overstreet wrote:
[..]
> diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
> index 95e52879..24e5cef 100644
> --- a/drivers/block/floppy.c
> +++ b/drivers/block/floppy.c
> @@ -3778,7 +3778,6 @@ static int __floppy_read_block_0(struct block_device *bdev)
> bio_vec.bv_len = size;
> bio_vec.bv_offset = 0;
> bio.bi_vcnt = 1;
> - bio.bi_idx = 0;
So leaving bio.bi_idx uninitialized is safer than setting it to zero? Can
you explain a bit more that why this change is required?
Thanks
Vivek
On Tue, Oct 02, 2012 at 03:24:34PM -0400, Vivek Goyal wrote:
> On Mon, Sep 24, 2012 at 03:34:49PM -0700, Kent Overstreet wrote:
>
> [..]
> > diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
> > index 95e52879..24e5cef 100644
> > --- a/drivers/block/floppy.c
> > +++ b/drivers/block/floppy.c
> > @@ -3778,7 +3778,6 @@ static int __floppy_read_block_0(struct block_device *bdev)
> > bio_vec.bv_len = size;
> > bio_vec.bv_offset = 0;
> > bio.bi_vcnt = 1;
> > - bio.bi_idx = 0;
>
> So leaving bio.bi_idx uninitialized is safer than setting it to zero? Can
> you explain a bit more that why this change is required?
It's not uninitialized, because it just called bio_init() - it was
entirely redundant before.
It's not strictly necessary, but immutable bio vecs require getting rid
of a lot of bi_idx usage, and everything that's left is either
unecessary or better/cleaner done some other way, so it's best to just
get rid of all of them - immutable bvecs changes the semantics of bi_idx
just enough that directly using it tends to be wrong.