Re: [PATCH 0/2] NFSv4/flexfiles: support loosely coupled data servers

[Mkrtchyan, Tigran]

----- Original Message -----
> From: "Jeuk Kim" <jeuk20.kim@xxxxxxxxx>
> To: "Trond Myklebust" <trondmy@xxxxxxxxxx>, "Anna Schumaker" <anna@xxxxxxxxxx>
> Cc: "linux-nfs" <linux-nfs@xxxxxxxxxxxxxxx>, "linux-kernel" <linux-kernel@xxxxxxxxxxxxxxx>, "Tigran Mkrtchyan"
> <tigran.mkrtchyan@xxxxxxx>, "hui81 qi" <hui81.qi@xxxxxxxxxxx>, "j-young choi" <j-young.choi@xxxxxxxxxxx>, "peng yun"
> <peng.yun@xxxxxxxxxxx>, "qian01 li" <qian01.li@xxxxxxxxxxx>, "xing1 he" <xing1.he@xxxxxxxxxxx>, "jeuk20 kim"
> <jeuk20.kim@xxxxxxxxxxx>
> Sent: Wednesday, 8 July, 2026 09:44:31
> Subject: [PATCH 0/2] NFSv4/flexfiles: support loosely coupled data servers

> RFC 8435 allows a flexfiles data server to be loosely coupled, i.e. an
> NFS server that does not advertise EXCHGID4_FLAG_USE_PNFS_DS via
> EXCHANGE_ID. The client currently ignores the ffdv_tightly_coupled flag
> and treats every DS as tightly coupled, so NFSv4.1+ I/O to a loosely
> coupled DS fails during DS setup.
> 
> Patch 2 threads the decoded tightly_coupled flag down to the DS connect
> path and, when it is false, skips the NFS_CS_PNFS flag and the
> is_ds_client() check.
> 
> Patch 1 fixes pre-existing NFSv4.0 DS crashes on the same path (the DS
> client has no session).
> 
> Jeuk Kim (2):
>  NFSv4/flexfiles: fix NULL dereference for NFSv4.0 data servers
>  NFSv4/flexfiles: support loosely coupled data servers
> 
> fs/nfs/filelayout/filelayoutdev.c         |  2 +-
> fs/nfs/flexfilelayout/flexfilelayout.c    |  3 ++-
> fs/nfs/flexfilelayout/flexfilelayoutdev.c |  3 ++-
> fs/nfs/internal.h                         |  3 ++-
> fs/nfs/nfs4client.c                       |  5 +++--
> fs/nfs/nfs4session.c                      | 21 ++++++++++++++-------
> fs/nfs/nfs4session.h                      |  3 ++-
> fs/nfs/pnfs.h                             |  3 ++-
> fs/nfs/pnfs_nfs.c                         | 14 +++++++++-----
> 9 files changed, 37 insertions(+), 20 deletions(-)
> 
> --
> 2.43.0


Just checked that the tightly coupled servers configuration is still ok.

Tested-by: "Tigran Mkrtchyan" <tigran.mkrtchyan@xxxxxxx>

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