Change the foreground mount behaviour so that we keep retrying

forever by default. This matches what mount_nfs did before revision
1.40, and it is the generally expected behaviour for NFS mounts.

Document the current defaults near the start of the man page and
mention the options that can be used to change them.

Discussed on:	-hackers

sbin/mount_nfs/mount_nfs.8

@@ -71,6 +71,28 @@ It implements the mount protocol as described in RFC 1094, Appendix A and
 .%T "NFS: Network File System Version 3 Protocol Specification" ,
 Appendix I.
 .Pp
+By default,
+.Nm
+keeps retrying until the mount succeeds.
+This behaviour is intended for filesystems listed in
+.Xr fstab 5
+that are critical to the boot process.
+For non-critical filesystems, the
+.Fl b
+and
+.Fl R
+flags provide mechanisms to prevent the boot process from hanging
+if the server is unavailable.
+.Pp
+If the server becomes unresponsive while an NFS filesystem is
+mounted, any new or outstanding file operations on that filesystem
+will hang uninterruptibly until the server comes back.
+To modify this default behaviour, see the
+.Fl i
+and
+.Fl s
+flags.
+.Pp
 The options are:
 .Bl -tag -width indent
 .It Fl 2
@@ -126,12 +148,8 @@ but untrustworthy users and the network cables are in secure areas this does
 help, but for normal desktop clients this does not apply.)
 .It Fl R
 Set the mount retry count to the specified value.
-A retry count of zero means to keep retrying forever.
-By default,
-.Nm
-retries forever on background mounts (see the
-.Fl b
-option), and otherwise tries just once.
+The default is a retry count of zero, which means to keep retrying
+forever.
 There is a 60 second delay between each attempt.
 .It Fl T
 Use TCP transport instead of UDP.

sbin/mount_nfs/mount_nfs.c

@@ -486,7 +486,8 @@ main(argc, argv)
 	name = *argv;
 
 	if (retrycnt == -1)
-		retrycnt = (opflags & BGRND) ? 0 : 1;
+		/* The default is to keep retrying forever. */
+		retrycnt = 0;
 	if (!getnfsargs(spec, nfsargsp))
 		exit(1);