[PATCH v4 0/7] smb: client: make more mount options take effect on remount

[rajasimandalos]

From: Rajasi Mandal <rajasimandal@xxxxxxxxxxxxx>

Several mount options are accepted by the remount (reconfigure) path but
silently have no effect: the new value is stored in cifs_sb->ctx but never
propagated to the live server/tcon structures, or the option is simply
ignored.  This is confusing -- the user passes an option on
'mount -o remount' and nothing changes, with no error.

This series makes the reconfigure path honest:

  - It first establishes a correct baseline for comparing old vs new
    options on remount by duplicating the live context (with runtime
    state synced in) instead of rebuilding from init defaults.

  - Options that are genuinely reconfigurable (retrans, rasize, nolease)
    are now applied to the running mount.

  - Options that are connection-tied and cannot take effect without
    tearing down the connection (seal, sign, vers, ip, srcaddr, rdma,
    cache=ro/singleclient, etc.) are now explicitly rejected with a clear
    error message instead of being silently dropped.

Patch 1 is preparatory plumbing (duplicate live ctx + sync runtime
state) that makes the simple != comparisons in the rejection checks
sound.  Patches 2 and 4 add the rejection checks.  Patches 3, 5 and 7
apply the reconfigurable options.  Patch 6 is a small no-functional-change
move of struct tcon_list so the nolease patch can reuse it.

Changes since v3:
  - nolease: moved tcon->no_lease out of the bitfield word into a plain
    bool, so propagating it on remount cannot race (via a bitfield
    read-modify-write) with the lockless need_reconnect/need_reopen_files
    writers on the reconnect/reopen paths.
  - srcaddr remount check now uses cifs_match_ipaddr() instead of a raw
    memcmp over sockaddr_storage, matching the adjacent ip check and
    avoiding port/padding fragility.

Rajasi Mandal (7):
  smb: client: sync runtime state into ctx on reconfigure
  smb: client: block non-reconfigurable option changes on remount
  smb: client: sync retrans on remount
  smb: client: block cache=ro and cache=singleclient on remount
  smb: client: apply rasize on remount
  smb: client: move struct tcon_list to cifsglob.h
  smb: client: allow nolease option to be reconfigured on remount

 fs/smb/client/cached_dir.c |  44 +++++
 fs/smb/client/cached_dir.h |   1 +
 fs/smb/client/cifs_swn.h   |  14 +-
 fs/smb/client/cifsglob.h   |   7 +-
 fs/smb/client/fs_context.c | 332 ++++++++++++++++++++++++++++++++++++-
 fs/smb/client/misc.c       |   5 -
 fs/smb/client/smb1ops.c    |   7 +-
 fs/smb/client/smb2pdu.c    |  11 +-
 fs/smb/client/trace.h      |   2 +
 9 files changed, 411 insertions(+), 12 deletions(-)


base-commit: 0eb17dea51eff940230b5e562df29ce457124d41
-- 
2.43.0