> On Dec 20, 2022, at 11:29, Olga Kornievskaia <olga.kornievskaia@xxxxxxxxx> 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@xxxxxxxxxx>
> ---
> 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/filelayout.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 *pgio, struct nfs_page *prev,
> size = pnfs_generic_pg_test(pgio, prev, req);
> if (!size)
> return 0;
> + else if (FILELAYOUT_LSEG(pgio->pg_lseg)->single_ds)
> + return size;
Hmm… Instead of adding the boolean, perhaps just add a helper function
static bool filelayout_lseg_is_striped(const struct nfs4_filelayout_segment *flseg)
{
return flseg->num_fh > 1;
}
that can be called here?
>
> /* see if req and prev are in the same stripe */
> if (prev) {
> diff --git a/fs/nfs/filelayout/filelayout.h b/fs/nfs/filelayout/filelayout.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/filelayoutdev.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 *lseg, u32 j)
> u32 i;
>
> if (flseg->stripe_type == STRIPE_SPARSE) {
> - if (flseg->num_fh == 1)
> + if (flseg->num_fh == 1) {
> + flseg->single_ds = true;
> i = 0;
> + }
> else if (flseg->num_fh == 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@xxxxxxxxxxxxxxx
