[PATCH v5 0/7] nfsd: CB_SEQUENCE error handling fixes and cleanups

[Jeff Layton]

This patch is mostly the same as the v4 series, but with the first
patch broken up into multiple changes (as Chuck suggested), and a few
changes to the comments.

Another minor difference here is that I didn't change the code to ignore
the return value of rpc_restart_call() and rpc_restart_call_prepare().
These could end up being backported to kernels that have to handle those
cases.

Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
Changes in v5:
- don't ignore return of rpc_restart_call() and rpc_restart_call_prepare()
- Break up the nfsd4_cb_sequence_done() error handling changes into multiple patches
- Link to v4: https://lore.kernel.org/r/20250207-nfsd-6-14-v4-0-1aa42c407265@xxxxxxxxxx

Changes in v4:
- Hold back on session refcounting changes for now and just send CB_SEQUENCE
  error handling rework.
- Link to v3: https://lore.kernel.org/r/20250129-nfsd-6-14-v3-0-506e71e39e6b@xxxxxxxxxx

Changes in v3:
- rename cb_session_changed to nfsd4_cb_session_changed
- rename restart_callback to requeue_callback, and rename need_restart:
  label to requeue:
- don't increment seq_nr on -ESERVERFAULT
- comment cleanups
- drop client-side rpc patch (will send separately)
- Link to v2: https://lore.kernel.org/r/20250129-nfsd-6-14-v2-0-2700c92f3e44@xxxxxxxxxx

Changes in v2:
- make nfsd4_session be RCU-freed
- change code to keep reference to session over callback RPCs
- rework error handling in nfsd4_cb_sequence_done()
- move NFSv4.0 handling out of nfsd4_cb_sequence_done()
- Link to v1: https://lore.kernel.org/r/20250123-nfsd-6-14-v1-0-c1137a4fa2ae@xxxxxxxxxx

---
Jeff Layton (7):
      nfsd: prepare nfsd4_cb_sequence_done() for error handling rework
      nfsd: always release slot when requeueing callback
      nfsd: only check RPC_SIGNALLED() when restarting rpc_task
      nfsd: when CB_SEQUENCE gets ESERVERFAULT don't increment seq_nr
      nfsd: handle CB_SEQUENCE NFS4ERR_BADSLOT better
      nfsd: handle CB_SEQUENCE NFS4ERR_SEQ_MISORDERED error better
      nfsd: lift NFSv4.0 handling out of nfsd4_cb_sequence_done()

 fs/nfsd/nfs4callback.c | 102 +++++++++++++++++++++++++++++--------------------
 1 file changed, 61 insertions(+), 41 deletions(-)
---
base-commit: 50934b1a613cabba2b917879c3e722882b72f628
change-id: 20250123-nfsd-6-14-b0797e385dc0

Best regards,
-- 
Jeff Layton <jlayton@xxxxxxxxxx>