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From:   Olga Kornievskaia <olga.kornievskaia@gmail.com>
Date:   Tue, 20 Dec 2022 12:32:18 -0500
Message-ID: <CAN-5tyHWyJi+r6+Ks1qB1EzuacwgBRMSt21SZL1N5r38KoBhdQ@mail.gmail.com>
Subject: Re: [PATCH 1/1] pNFS/filelayout: Fix coalescing test for single DS
To:     Trond Myklebust <trondmy@hammerspace.com>
Cc:     Anna Schumaker <anna.schumaker@netapp.com>,
        "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>
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On Tue, Dec 20, 2022 at 11:37 AM Trond Myklebust
<trondmy@hammerspace.com> wrote:
>
>
>
> > On Dec 20, 2022, at 11:29, Olga Kornievskaia <olga.kornievskaia@gmail.c=
om> wrote:
> >
> > When there is a single DS no striping constraints need to be placed on
> > the IO. When such constraint is applied then buffered reads don't
> > coalesce to the DS's rsize.
> >
> > Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
> > ---
> > fs/nfs/filelayout/filelayout.c    | 2 ++
> > fs/nfs/filelayout/filelayout.h    | 1 +
> > fs/nfs/filelayout/filelayoutdev.c | 4 +++-
> > 3 files changed, 6 insertions(+), 1 deletion(-)
> >
> > diff --git a/fs/nfs/filelayout/filelayout.c b/fs/nfs/filelayout/filelay=
out.c
> > index ad34a33b0737..cd819b795935 100644
> > --- a/fs/nfs/filelayout/filelayout.c
> > +++ b/fs/nfs/filelayout/filelayout.c
> > @@ -803,6 +803,8 @@ filelayout_pg_test(struct nfs_pageio_descriptor *pg=
io, struct nfs_page *prev,
> > size =3D pnfs_generic_pg_test(pgio, prev, req);
> > if (!size)
> > return 0;
> > + else if (FILELAYOUT_LSEG(pgio->pg_lseg)->single_ds)
> > + return size;
>
> Hmm=E2=80=A6 Instead of adding the boolean, perhaps just add a helper fun=
ction
>
> static bool filelayout_lseg_is_striped(const struct nfs4_filelayout_segme=
nt *flseg)
> {
>         return flseg->num_fh > 1;
> }
>
> that can be called here?

Thank you. v2 is on the way.

>
> >
> > /* see if req and prev are in the same stripe */
> > if (prev) {
> > diff --git a/fs/nfs/filelayout/filelayout.h b/fs/nfs/filelayout/filelay=
out.h
> > index aed0748fd6ec..524920c2cbf8 100644
> > --- a/fs/nfs/filelayout/filelayout.h
> > +++ b/fs/nfs/filelayout/filelayout.h
> > @@ -65,6 +65,7 @@ struct nfs4_filelayout_segment {
> > struct nfs4_file_layout_dsaddr *dsaddr; /* Point to GETDEVINFO data */
> > unsigned int num_fh;
> > struct nfs_fh **fh_array;
> > + bool single_ds;
> > };
> >
> > struct nfs4_filelayout {
> > diff --git a/fs/nfs/filelayout/filelayoutdev.c b/fs/nfs/filelayout/file=
layoutdev.c
> > index acf4b88889dc..95ebbe9e7ed4 100644
> > --- a/fs/nfs/filelayout/filelayoutdev.c
> > +++ b/fs/nfs/filelayout/filelayoutdev.c
> > @@ -243,8 +243,10 @@ nfs4_fl_select_ds_fh(struct pnfs_layout_segment *l=
seg, u32 j)
> > u32 i;
> >
> > if (flseg->stripe_type =3D=3D STRIPE_SPARSE) {
> > - if (flseg->num_fh =3D=3D 1)
> > + if (flseg->num_fh =3D=3D 1) {
> > + flseg->single_ds =3D true;
> > i =3D 0;
> > + }
> > else if (flseg->num_fh =3D=3D 0)
> > /* Use the MDS OPEN fh set in nfs_read_rpcsetup */
> > return NULL;
> > --
> > 2.31.1
> >
>
>
>
> _________________________________
> Trond Myklebust
> Linux NFS client maintainer, Hammerspace
> trond.myklebust@hammerspace.com
>