On Tue, Oct 02, 2012 at 11:37:37AM -0400, Vivek Goyal wrote:
> On Mon, Sep 24, 2012 at 03:34:42PM -0700, Kent Overstreet wrote:
>
> [..]
> > /**
> > * bio_integrity_alloc - Allocate integrity payload and attach it to bio
> > * @bio: bio to attach integrity metadata to
> > @@ -84,37 +47,39 @@ struct bio_integrity_payload
> > *bio_integrity_alloc(struct bio *bio,
> > unsigned int nr_vecs)
> > {
> > struct bio_integrity_payload *bip;
> > - unsigned int idx = vecs_to_idx(nr_vecs);
> > struct bio_set *bs = bio->bi_pool;
> > + unsigned long idx = BIO_POOL_NONE;
> > + unsigned inline_vecs;
> > +
> > + if (!bs) {
> > + bip = kmalloc(sizeof(struct bio_integrity_payload) +
> > + sizeof(struct bio_vec) * nr_vecs, gfp_mask);
> > + inline_vecs = nr_vecs;
> > + } else {
> > + bip = mempool_alloc(bs->bio_integrity_pool, gfp_mask);
> > + inline_vecs = BIP_INLINE_VECS;
> > + }
> >
> > - if (!bs)
> > - bs = fs_bio_set;
>
> Ok, this is change of behavior. Previously we will fall back to fs_bio_set
> and now you do kmalloc. This change looks to be independent of bip_vec
> pointer. Can you please break it out in a separate patch and also explain
> that how does this change help.
I'm not sure it's worth breaking out into a separate patch, but I
definitely should've mentioned it in the patch description.
It just didn't make sense to be using fs_bio_set if a bio_set wasn't
specified before - if a bio set wasn't specified we're still using
kmalloc for the bio_integrity_payload, so we're not protected from
memory allocation failures and it doesn't buy us anything.
All it does is introduce the possibility of deadlock, if we weren't
supposed to be using fs_bio_set for whatever reason.
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