mount.nfs: Update description of clientaddr= in nfs(5)

[nfs-utils.git] / utils / mount / nfs.man

diff --git a/utils/mount/nfs.man b/utils/mount/nfs.man
index 8abdb8394ead612b2597fc3cf067d42a448df48d..d92da1905a74a64cdc882e93ac90176abcacce52 100644 (file)
--- a/utils/mount/nfs.man
+++ b/utils/mount/nfs.man
@@ -283,6 +283,28 @@ support UDP.
 .TP 1.5i
 .I udp
 Mount the NFS filesystem using the UDP protocol.
+.TP 1.5i
+.I nordirplus
+Disables NFSv3 READDIRPLUS RPCs. Use this option when
+mounting servers that don't support or have broken
+READDIRPLUS implementations.
+.TP 1.5i
+.I nosharecache
+As of kernel 2.6.18, it is no longer possible to mount the same
+same filesystem with different mount options to a new mountpoint.
+It was deemed unsafe to do so, since cached data cannot be shared
+between the two mountpoints. In consequence, files or directories
+that were common to both mountpoint subtrees could often be seen to
+be out of sync following an update.
+.br
+This option allows administrators to select the pre-2.6.18 behaviour,
+permitting the same filesystem to be mounted with different mount
+options.
+.br
+.B Beware:
+Use of this option is not recommended unless you are certain that there
+are no hard links or subtrees of this mountpoint that are mounted
+elsewhere.
 .P
 All of the non-value options have corresponding nooption forms.
 For example, nointr means don't allow file operations to be
@@ -389,11 +411,23 @@ Valid protocol types are
 and
 .IR tcp .
 .TP 1.5i
-.I clientaddr=n
-On a multi-homed client, this
-causes the client to use a specific callback address when
-communicating with an NFS version 4 server.
-This option is currently ignored.
+.I clientaddr=n.n.n.n
+Specifies a single IPv4 address in dotted-quad form that
+the NFS client advertises to allow servers to perform
+NFSv4 callback requests against files on this mount point.
+If the server is not able to establish callback connections
+to clients, performance may degrade, or accesses to
+files may temporarily hang.
+.IP
+If this option is not specified, the
+.BR mount (8)
+command attempts to discover an appropriate callback
+address automatically.
+The automatic discovery process is not perfect, however.
+In the presence of multiple client network interfaces, special
+routing policies, or atypical network topologies, the exact
+address to use for callbacks may be nontrivial to determine,
+and should be explicitly set using this mount option.
 .TP 1.5i
 .I sec=mode
 Same as \f3sec=mode\f1 for the nfs filesystem type (see above).
@@ -439,6 +473,23 @@ This extracts a
 server performance penalty but it allows two different NFS clients
 to get reasonable good results when both clients are actively
 writing to common filesystem on the server.
+.TP 1.5i
+.I nosharecache
+As of kernel 2.6.18, it is no longer possible to mount the same
+same filesystem with different mount options to a new mountpoint.
+It was deemed unsafe to do so, since cached data cannot be shared
+between the two mountpoints. In consequence, files or directories
+that were common to both mountpoint subtrees could often be seen to
+be out of sync following an update.
+.br
+This option allows administrators to select the pre-2.6.18 behaviour,
+permitting the same filesystem to be mounted with different mount
+options.
+.br
+.B Beware:
+Use of this option is not recommended unless you are certain that there
+are no hard links or subtrees of this mountpoint that are mounted
+elsewhere.
 .P
 All of the non-value options have corresponding nooption forms.
 For example, nointr means don't allow file operations to be