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
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).
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