mount: make FEATURE_MOUNT_NFS not needed for Linux 2.6.23+

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

2 files changed, 49 insertions, 9 deletions

diff --git a/util-linux/Config.src b/util-linux/Config.src
index 888bc8f3b..57a52cefb 100644
--- a/util-linux/Config.src
+++ b/util-linux/Config.src
@@ -485,13 +485,18 @@ config FEATURE_MOUNT_LABEL
           This also enables label or uuid support for swapon.
 
 config FEATURE_MOUNT_NFS
-        bool "Support mounting NFS file systems"
-        default y
+        bool "Support mounting NFS file systems on Linux < 2.6.23"
+        default n
         depends on MOUNT
         select FEATURE_HAVE_RPC
         select FEATURE_SYSLOG
         help
-          Enable mounting of NFS file systems.
+          Enable mounting of NFS file systems on Linux kernels prior
+          to version 2.6.23. Note that in this case mounting of NFS
+          over IPv6 will not be possible.
+
+          Note that this option links in RPC support from libc,
+          which is rather large (~10 kbytes on uclibc).
 
 config FEATURE_MOUNT_CIFS
         bool "Support mounting CIFS/SMB file systems"
diff --git a/util-linux/mount.c b/util-linux/mount.c
index 1dd4c0c43..7ae1981c8 100644
--- a/util-linux/mount.c
+++ b/util-linux/mount.c
@@ -1144,7 +1144,7 @@ static NOINLINE int nfsmount(struct mntent *mp, long vfsflags, char *filteropts)
         pathname = s + 1;
         *s = '\0';
         /* Ignore all but first hostname in replicated mounts
-           until they can be fully supported. (mack@sgi.com) */
+         * until they can be fully supported. (mack@sgi.com) */
         s = strchr(hostname, ',');
         if (s) {
                 *s = '\0';
@@ -1683,7 +1683,6 @@ static NOINLINE int nfsmount(struct mntent *mp, long vfsflags, char *filteropts)
 
         /* Perform actual mount */
  do_mount:
-        mp->mnt_type = (char*)"nfs";
         retval = mount_it_now(mp, vfsflags, (char*)&data);
         goto ret;
 
@@ -1708,8 +1707,43 @@ static NOINLINE int nfsmount(struct mntent *mp, long vfsflags, char *filteropts)
 
 #else // !ENABLE_FEATURE_MOUNT_NFS
 
-// Never called. Call should be optimized out.
-int nfsmount(struct mntent *mp, long vfsflags, char *filteropts);
+/* Linux 2.6.23+ supports nfs mounts with options passed as a string.
+ * For older kernels, you must build busybox with ENABLE_FEATURE_MOUNT_NFS.
+ * (However, note that then you lose any chances that NFS over IPv6 would work).
+ */
+static int nfsmount(struct mntent *mp, long vfsflags, char *filteropts)
+{
+        len_and_sockaddr *lsa;
+        char *opts;
+        char *end;
+        char *dotted;
+        int ret;
+
+# if ENABLE_FEATURE_IPV6
+        end = strchr(mp->mnt_fsname, ']');
+        if (end && end[1] == ':')
+                end++;
+        else
+# endif
+                /* mount_main() guarantees that ':' is there */
+                end = strchr(mp->mnt_fsname, ':');
+
+        *end = '\0';
+        lsa = xdotted2sockaddr(mp->mnt_fsname, /*port:*/ 0);
+        *end = ':';
+        dotted = xmalloc_sockaddr2dotted_noport(&lsa->u.sa);
+        if (ENABLE_FEATURE_CLEAN_UP) free(lsa);
+        opts = xasprintf("%s%saddr=%s",
+                filteropts ? filteropts : "",
+                filteropts ? "," : "",
+                dotted
+        );
+        if (ENABLE_FEATURE_CLEAN_UP) free(dotted);
+        ret = mount_it_now(mp, vfsflags, opts);
+        if (ENABLE_FEATURE_CLEAN_UP) free(opts);
+
+        return ret;
+}
 
 #endif // !ENABLE_FEATURE_MOUNT_NFS
 
@@ -1800,10 +1834,11 @@ static int singlemount(struct mntent *mp, int ignore_busy)
         }
 
         // Might this be an NFS filesystem?
-        if (ENABLE_FEATURE_MOUNT_NFS
-         && (!mp->mnt_type || strcmp(mp->mnt_type, "nfs") == 0)
+        if ((!mp->mnt_type || strncmp(mp->mnt_type, "nfs", 3) == 0)
          && strchr(mp->mnt_fsname, ':') != NULL
         ) {
+                if (!mp->mnt_type)
+                        mp->mnt_type = (char*)"nfs";
                 rc = nfsmount(mp, vfsflags, filteropts);
                 goto report_error;
         }