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From:   "NeilBrown" <neilb@suse.de>
To:     "Trond Myklebust" <trondmy@hammerspace.com>,
        "Anna Schumaker" <anna@kernel.org>
Cc:     "Chuck Lever III" <chuck.lever@oracle.com>,
        "Linux NFS Mailing List" <linux-nfs@vger.kernel.org>
Subject: [PATCH v2] NFS: update documentation for the nfs4_unique_id parameter
In-reply-to: <164783633625.6096.14575868633417140042@noble.neil.brown.name>
References: <164783633625.6096.14575868633417140042@noble.neil.brown.name>
Date:   Mon, 21 Mar 2022 16:20:43 +1100
Message-id: <164784004337.6096.413613952857713019@noble.neil.brown.name>
Precedence: bulk


The documentation for nfs4_unique_id is out-of-date.  In particular it
claim that when nfs4_unique_id is set, the host name is not used.  since
Commit 55b592933b7d ("NFSv4: Fix nfs4_init_uniform_client_string for net
namespaces") both the unique_id AND the host name are used.

Update the documentation to match the code.

Signed-off-by: NeilBrown <neilb@suse.de>
---

After writing the first version I realised that when 'identifier' is set
it overrides the module parameter, rather than supplements it.  Hence v2.

 Documentation/admin-guide/nfs/nfs-client.rst | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/Documentation/admin-guide/nfs/nfs-client.rst b/Documentation/adm=
in-guide/nfs/nfs-client.rst
index 6adb6457bc69..36760685dd34 100644
--- a/Documentation/admin-guide/nfs/nfs-client.rst
+++ b/Documentation/admin-guide/nfs/nfs-client.rst
@@ -36,10 +36,9 @@ administrative requirements that require particular behavi=
or that does not
 work well as part of an nfs_client_id4 string.
=20
 The nfs.nfs4_unique_id boot parameter specifies a unique string that can be
-used instead of a system's node name when an NFS client identifies itself to
-a server.  Thus, if the system's node name is not unique, or it changes, its
-nfs.nfs4_unique_id stays the same, preventing collision with other clients
-or loss of state during NFS reboot recovery or transparent state migration.
+used together with  a system's node name when an NFS client identifies itsel=
f to
+a server.  Thus, if the system's node name is not unique, its
+nfs.nfs4_unique_id can help prevent collisions with other clients.
=20
 The nfs.nfs4_unique_id string is typically a UUID, though it can contain
 anything that is believed to be unique across all NFS clients.  An
@@ -53,8 +52,12 @@ outstanding NFSv4 state has expired, to prevent loss of NF=
Sv4 state.
=20
 This string can be stored in an NFS client's grub.conf, or it can be provided
 via a net boot facility such as PXE.  It may also be specified as an nfs.ko
-module parameter.  Specifying a uniquifier string is not support for NFS
-clients running in containers.
+module parameter.
+
+This uniquifier string will be the same for all NFS clients running in
+containers unless it is overridden by a value written to
+/sys/fs/nfs/net/nfs_client/identifier which will be local to the network
+namespace of the process which writes.
=20
=20
 The DNS resolver
--=20
2.35.1