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From:   Trond Myklebust <trondmy@hammerspace.com>
To:     Olga Kornievskaia <olga.kornievskaia@gmail.com>
CC:     Trond Myklebust <trondmy@hammerspace.com>,
        Anna Schumaker <anna.schumaker@netapp.com>,
        "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>
Subject: Re: [PATCH v2] pNFS/filelayout: Fix coalescing test for single DS
Thread-Topic: [PATCH v2] pNFS/filelayout: Fix coalescing test for single DS
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Date:   Tue, 20 Dec 2022 18:32:38 +0000
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References: <20221220173129.98009-1-olga.kornievskaia@gmail.com>
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> On Dec 20, 2022, at 12:31, Olga Kornievskaia <olga.kornievskaia@gmail.com=
> wrote:
>=20
> 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.
>=20
> Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
> ---
> fs/nfs/filelayout/filelayout.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>=20
> diff --git a/fs/nfs/filelayout/filelayout.c b/fs/nfs/filelayout/filelayou=
t.c
> index ad34a33b0737..4974cd18ca46 100644
> --- a/fs/nfs/filelayout/filelayout.c
> +++ b/fs/nfs/filelayout/filelayout.c
> @@ -783,6 +783,12 @@ filelayout_alloc_lseg(struct pnfs_layout_hdr *layout=
id,
> return &fl->generic_hdr;
> }
>=20
> +static bool
> +filelayout_lseg_is_striped(const struct nfs4_filelayout_segment *flseg)
> +{
> + return flseg->num_fh > 1;
> +}
> +
> /*
>  * filelayout_pg_test(). Called by nfs_can_coalesce_requests()
>  *
> @@ -803,6 +809,8 @@ filelayout_pg_test(struct nfs_pageio_descriptor *pgio=
, struct nfs_page *prev,
> size =3D pnfs_generic_pg_test(pgio, prev, req);
> if (!size)
> return 0;
> + else if (!filelayout_lseg_is_striped(FILELAYOUT_LSEG(pgio->pg_lseg)))
> + return size;
>=20
> /* see if req and prev are in the same stripe */
> if (prev) {
> --=20
> 2.31.1
>=20

That works for me. Thanks!
_________________________________
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@hammerspace.com