Add command line options to mount.nfs that allow it to prioritize DNS
resolution results for a server with interfaces registered for both
families.
Since this is a mount.nfs command line option and not something more
visible at higher levels (like as a mount option), consider this feature
useful mostly for testing.
Signed-off-by: Chuck Lever <[email protected]>
---
utils/mount/mount.c | 15 ++++++++++++++-
utils/mount/mount.nfs.man | 8 ++++++++
utils/mount/stropts.c | 3 ++-
3 files changed, 24 insertions(+), 2 deletions(-)
diff --git a/utils/mount/mount.c b/utils/mount/mount.c
index 33d8d30..eecf1ad 100644
--- a/utils/mount/mount.c
+++ b/utils/mount/mount.c
@@ -54,6 +54,7 @@ int nomtab;
int verbose;
int sloppy;
int string;
+int dnsfamily = AF_INET;
#define FOREGROUND (0)
#define BACKGROUND (1)
@@ -294,6 +295,10 @@ void mount_usage(void)
printf(_("\t-v\t\tVerbose\n"));
printf(_("\t-V\t\tPrint version\n"));
printf(_("\t-w\t\tMount file system read-write\n"));
+#if IPV6_SUPPORTED
+ printf(_("\t-4\t\tFavor IPv4 DNS resolution results\n"));
+ printf(_("\t-6\t\tFavor IPv6 DNS resolution results\n"));
+#endif
printf(_("\t-f\t\tFake mount, do not actually mount\n"));
printf(_("\t-n\t\tDo not update /etc/mtab\n"));
printf(_("\t-s\t\tTolerate sloppy mount options rather than fail\n"));
@@ -442,7 +447,7 @@ int main(int argc, char *argv[])
mount_point = argv[2];
argv[2] = argv[0]; /* so that getopt error messages are correct */
- while ((c = getopt_long(argc - 2, argv + 2, "rvVwfno:hs",
+ while ((c = getopt_long(argc - 2, argv + 2, "rvVw46fno:hs",
longopts, NULL)) != -1) {
switch (c) {
case 'r':
@@ -457,6 +462,14 @@ int main(int argc, char *argv[])
case 'w':
flags &= ~MS_RDONLY;
break;
+#if IPV6_SUPPORTED
+ case '4':
+ dnsfamily = AF_INET;
+ break;
+ case '6':
+ dnsfamily = AF_INET6;
+ break;
+#endif
case 'f':
++fake;
break;
diff --git a/utils/mount/mount.nfs.man b/utils/mount/mount.nfs.man
index 1a4561b..9526d9e 100644
--- a/utils/mount/mount.nfs.man
+++ b/utils/mount/mount.nfs.man
@@ -39,6 +39,14 @@ Print version.
.BI "\-w"
Mount file system read-write.
.TP
+.BI "\-4"
+If a server has both IPv4 and IPv6 interfaces,
+favor IPv4 results when resolving the server's hostname to an IP address.
+.TP
+.BI "\-6"
+If a server has both IPv4 and IPv6 interfaces,
+favor IPv6 results when resolving the server's hostname to an IP address.
+.TP
.BI "\-f"
Fake mount. Don't actually call the mount system call.
.TP
diff --git a/utils/mount/stropts.c b/utils/mount/stropts.c
index caf13b1..eef9ebf 100644
--- a/utils/mount/stropts.c
+++ b/utils/mount/stropts.c
@@ -71,6 +71,7 @@
extern int nfs_mount_data_version;
extern char *progname;
extern int verbose;
+extern int dnsfamily;
static int parse_devname(const char *spec, char **hostname)
{
@@ -732,7 +733,7 @@ int nfsmount_string(const char *spec, const char *node, const char *type,
if (!parse_devname(spec, &hostname))
return retval;
- if (nfs_name_to_address(hostname, AF_UNSPEC, saddr))
+ if (nfs_name_to_address(hostname, dnsfamily, saddr))
goto fail;
options = po_split(*extra_opts);