NFSv4/flexfiles: fix NULL dereference for NFSv4.0 data servers

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flexfiles accepts NFSv4.0 data servers, but two NFSv4 code paths assume
the data server client has a session. Unlike NFSv4.1+, an NFSv4.0 client
has no session (clp->cl_session is NULL; it uses clp->cl_slot_tbl), so
I/O to a v4.0 flexfiles DS oopses:

  - nfs4_init_ds_session() dereferences clp->cl_session->session_state
    while seeding the DS lease. It also only seeds cl_lease_time when
    NFS4_SESSION_INITING is set; without a session that never happens, so
    cl_lease_time stays 0 and nfs4_renew_state() busy-loops, requeuing
    every 5 seconds. Seed the lease whenever there is no session and
    return before touching session state.

  - ff_layout_async_handle_error_v4() dereferences
    clp->cl_session->fc_slot_table on every DS I/O error. Fall back to the
    v4.0 transport slot table (clp->cl_slot_tbl) when there is no session.

Fixes: a7878ca140 ("nfs: flexfilelayout: remove v3-only data server limitation")
Signed-off-by: Jeuk Kim <jeuk20.kim@samsung.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

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Jeuk Kim 2026-07-08 16:44:32 +09:00 • committed by Trond Myklebust

parent 8cb1ce7aa0

commit 2b03ebbf8d

2 changed files with 13 additions and 6 deletions

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3

fs/nfs/flexfilelayout/flexfilelayout.c

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16

fs/nfs/nfs4session.c

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