]> git.decadent.org.uk Git - nfs-utils.git/blobdiff - utils/mount/stropts.c
mount.nfs: Assume v2/v3 if mount-related options are present
[nfs-utils.git] / utils / mount / stropts.c
index bd127ab6bc017e8e9fef2c267666c752571b555c..a0b9e7fdf80a0f8967bda37c05b1ee34444769a0 100644 (file)
@@ -45,6 +45,7 @@
 #include "parse_opt.h"
 #include "version.h"
 #include "parse_dev.h"
+#include "conffile.h"
 
 #ifndef NFS_PROGRAM
 #define NFS_PROGRAM    (100003)
@@ -80,17 +81,37 @@ struct nfsmount_info {
                                *node,          /* mounted-on dir */
                                *type;          /* "nfs" or "nfs4" */
        char                    *hostname;      /* server's hostname */
+       struct sockaddr_storage address;        /* server's address */
+       socklen_t               salen;          /* size of server's address */
 
        struct mount_options    *options;       /* parsed mount options */
        char                    **extra_opts;   /* string for /etc/mtab */
 
+       unsigned long           version;        /* NFS version */
        int                     flags,          /* MS_ flags */
                                fake,           /* actually do the mount? */
                                child;          /* forked bg child? */
-
-       sa_family_t             family;         /* supported address family */
 };
 
+#ifdef MOUNT_CONFIG
+static void nfs_default_version(struct nfsmount_info *mi);
+
+static void nfs_default_version(struct nfsmount_info *mi)
+{
+       extern unsigned long config_default_vers;
+       /*
+        * Use the default value set in the config file when
+        * the version has not been explicitly set.
+        */
+       if (mi->version == 0 && config_default_vers) {
+               if (config_default_vers < 4)
+                       mi->version = config_default_vers;
+       }
+}
+#else
+inline void nfs_default_version(struct nfsmount_info *mi) {}
+#endif /* MOUNT_CONFIG */
+
 /*
  * Obtain a retry timeout value based on the value of the "retry=" option.
  *
@@ -132,12 +153,14 @@ static int nfs_append_generic_address_option(const struct sockaddr *sap,
 {
        char address[NI_MAXHOST];
        char new_option[512];
+       int len;
 
        if (!nfs_present_sockaddr(sap, salen, address, sizeof(address)))
                goto out_err;
 
-       if (snprintf(new_option, sizeof(new_option), "%s=%s",
-                                       keyword, address) >= sizeof(new_option))
+       len = snprintf(new_option, sizeof(new_option), "%s=%s",
+                                               keyword, address);
+       if (len < 0 || (size_t)len >= sizeof(new_option))
                goto out_err;
 
        if (po_append(options, new_option) != PO_SUCCEEDED)
@@ -198,8 +221,7 @@ static int nfs_append_clientaddr_option(const struct sockaddr *sap,
  * Resolve the 'mounthost=' hostname and append a new option using
  * the resulting address.
  */
-static int nfs_fix_mounthost_option(const sa_family_t family,
-                                   struct mount_options *options)
+static int nfs_fix_mounthost_option(struct mount_options *options)
 {
        struct sockaddr_storage dummy;
        struct sockaddr *sap = (struct sockaddr *)&dummy;
@@ -210,7 +232,7 @@ static int nfs_fix_mounthost_option(const sa_family_t family,
        if (!mounthost)
                return 1;
 
-       if (!nfs_name_to_address(mounthost, family, sap, &salen)) {
+       if (!nfs_name_to_address(mounthost, sap, &salen)) {
                nfs_error(_("%s: unable to determine mount server's address"),
                                progname);
                return 0;
@@ -232,7 +254,7 @@ static const char *nfs_lock_opttbl[] = {
 
 static int nfs_verify_lock_option(struct mount_options *options)
 {
-       if (po_rightmost(options, nfs_lock_opttbl) == 1)
+       if (po_rightmost(options, nfs_lock_opttbl) == 0)
                return 1;
 
        if (!start_statd()) {
@@ -256,231 +278,273 @@ static int nfs_append_sloppy_option(struct mount_options *options)
        return 1;
 }
 
+static int nfs_set_version(struct nfsmount_info *mi)
+{
+       if (!nfs_nfs_version(mi->options, &mi->version))
+               return 0;
+
+       if (strncmp(mi->type, "nfs4", 4) == 0)
+               mi->version = 4;
+       else {
+               char *option = po_get(mi->options, "proto");
+               if (option && strcmp(option, "rdma") == 0)
+                       mi->version = 3;
+       }
+
+       /*
+        * If we still don't know, check for version-specific
+        * mount options.
+        */
+       if (mi->version == 0) {
+               if (po_contains(mi->options, "mounthost") ||
+                   po_contains(mi->options, "mountaddr") ||
+                   po_contains(mi->options, "mountvers") ||
+                   po_contains(mi->options, "mountproto"))
+                       mi->version = 3;
+       }
+
+       /*
+        * If enabled, see if the default version was
+        * set in the config file
+        */
+       nfs_default_version(mi);
+       
+       return 1;
+}
+
 /*
- * Set up mandatory NFS mount options.
+ * Set up mandatory non-version specific NFS mount options.
  *
  * Returns 1 if successful; otherwise zero.
  */
 static int nfs_validate_options(struct nfsmount_info *mi)
 {
-       struct sockaddr_storage dummy;
-       struct sockaddr *sap = (struct sockaddr *)&dummy;
-       socklen_t salen = sizeof(dummy);
+       struct sockaddr *sap = (struct sockaddr *)&mi->address;
 
        if (!nfs_parse_devname(mi->spec, &mi->hostname, NULL))
                return 0;
 
-       if (!nfs_name_to_address(mi->hostname, mi->family, sap, &salen))
+       mi->salen = sizeof(mi->address);
+       if (!nfs_name_to_address(mi->hostname, sap, &mi->salen))
                return 0;
 
-       if (strncmp(mi->type, "nfs4", 4) == 0) {
-               if (!nfs_append_clientaddr_option(sap, salen, mi->options))
-                       return 0;
-       } else {
-               if (!nfs_fix_mounthost_option(mi->family, mi->options))
-                       return 0;
-               if (!mi->fake && !nfs_verify_lock_option(mi->options))
-                       return 0;
-       }
+       if (!nfs_set_version(mi))
+               return 0;
 
        if (!nfs_append_sloppy_option(mi->options))
                return 0;
 
-       return nfs_append_addr_option(sap, salen, mi->options);
-}
+       if (!nfs_append_addr_option(sap, mi->salen, mi->options))
+               return 0;
 
-/*
- * Distinguish between permanent and temporary errors.
- *
- * Returns 0 if the passed-in error is temporary, thus the
- * mount system call should be retried; returns one if the
- * passed-in error is permanent, thus the mount system call
- * should not be retried.
- */
-static int nfs_is_permanent_error(int error)
-{
-       switch (error) {
-       case ESTALE:
-       case ETIMEDOUT:
-       case ECONNREFUSED:
-               return 0;       /* temporary */
-       default:
-               return 1;       /* permanent */
-       }
+       return 1;
 }
 
 /*
- * Reconstruct the mount option string based on a portmapper probe
- * of the server.  Returns one if the server's portmapper returned
- * something we can use, otherwise zero.
+ * Get NFS/mnt server addresses from mount options
  *
- * To handle version and transport protocol fallback properly, we
- * need to parse some of the mount options in order to set up a
- * portmap probe.  Mount options that nfs_rewrite_mount_options()
- * doesn't recognize are left alone.
- *
- * Returns a new group of mount options if successful; otherwise
- * NULL is returned if some failure occurred.
+ * Returns 1 and fills in @nfs_saddr, @nfs_salen, @mnt_saddr, and @mnt_salen
+ * if all goes well; otherwise zero.
  */
-static const char *nfs_transport_opttbl[] = {
-       "udp",
-       "tcp",
-       NULL,
-};
-
-static struct mount_options *nfs_rewrite_mount_options(char *str)
+static int nfs_extract_server_addresses(struct mount_options *options,
+                                       struct sockaddr *nfs_saddr,
+                                       socklen_t *nfs_salen,
+                                       struct sockaddr *mnt_saddr,
+                                       socklen_t *mnt_salen)
 {
-       struct mount_options *options;
-       char *option, new_option[64];
-       clnt_addr_t mnt_server = { };
-       clnt_addr_t nfs_server = { };
-       int p;
+       char *option;
 
-       options = po_split(str);
-       if (!options) {
-               errno = EFAULT;
-               return NULL;
-       }
-
-       errno = EINVAL;
        option = po_get(options, "addr");
-       if (option) {
-               nfs_server.saddr.sin_family = AF_INET;
-               if (!inet_aton((const char *)option, &nfs_server.saddr.sin_addr))
-                       goto err;
-       } else
-               goto err;
+       if (option == NULL)
+               return 0;
+       if (!nfs_string_to_sockaddr(option, nfs_saddr, nfs_salen))
+               return 0;
 
        option = po_get(options, "mountaddr");
-       if (option) {
-               mnt_server.saddr.sin_family = AF_INET;
-               if (!inet_aton((const char *)option, &mnt_server.saddr.sin_addr))
-                       goto err;
-       } else
-               memcpy(&mnt_server.saddr, &nfs_server.saddr,
-                               sizeof(mnt_server.saddr));
-
-       option = po_get(options, "mountport");
-       if (option)
-               mnt_server.pmap.pm_port = atoi(option);
-       mnt_server.pmap.pm_prog = MOUNTPROG;
-       option = po_get(options, "mountvers");
-       if (option)
-               mnt_server.pmap.pm_vers = atoi(option);
-       option = po_get(options, "mountproto");
-       if (option) {
-               if (strcmp(option, "tcp") == 0) {
-                       mnt_server.pmap.pm_prot = IPPROTO_TCP;
-                       po_remove_all(options, "mountproto");
-               }
-               if (strcmp(option, "udp") == 0) {
-                       mnt_server.pmap.pm_prot = IPPROTO_UDP;
-                       po_remove_all(options, "mountproto");
-               }
-       }
+       if (option == NULL) {
+               memcpy(mnt_saddr, nfs_saddr, *nfs_salen);
+               *mnt_salen = *nfs_salen;
+       } else if (!nfs_string_to_sockaddr(option, mnt_saddr, mnt_salen))
+               return 0;
 
-       option = po_get(options, "port");
-       if (option) {
-               nfs_server.pmap.pm_port = atoi(option);
-               po_remove_all(options, "port");
-       }
-       nfs_server.pmap.pm_prog = NFS_PROGRAM;
+       return 1;
+}
 
-       option = po_get(options, "nfsvers");
-       if (option) {
-               nfs_server.pmap.pm_vers = atoi(option);
-               po_remove_all(options, "nfsvers");
-       }
-       option = po_get(options, "vers");
-       if (option) {
-               nfs_server.pmap.pm_vers = atoi(option);
-               po_remove_all(options, "vers");
-       }
-       option = po_get(options, "proto");
-       if (option) {
-               if (strcmp(option, "tcp") == 0) {
-                       nfs_server.pmap.pm_prot = IPPROTO_TCP;
-                       po_remove_all(options, "proto");
-               }
-               if (strcmp(option, "udp") == 0) {
-                       nfs_server.pmap.pm_prot = IPPROTO_UDP;
-                       po_remove_all(options, "proto");
-               }
-       }
-       p = po_rightmost(options, nfs_transport_opttbl);
-       switch (p) {
-       case 1:
-               nfs_server.pmap.pm_prot = IPPROTO_UDP;
-               break;
-       case 2:
-               nfs_server.pmap.pm_prot = IPPROTO_TCP;
-               break;
-       }
-       po_remove_all(options, "tcp");
-       po_remove_all(options, "udp");
+static int nfs_construct_new_options(struct mount_options *options,
+                                    struct pmap *nfs_pmap,
+                                    struct pmap *mnt_pmap)
+{
+       char new_option[64];
 
-       if (!probe_bothports(&mnt_server, &nfs_server)) {
-               errno = ESPIPE;
-               goto err;
-       }
+       po_remove_all(options, "nfsprog");
+       po_remove_all(options, "mountprog");
 
+       po_remove_all(options, "v2");
+       po_remove_all(options, "v3");
+       po_remove_all(options, "vers");
+       po_remove_all(options, "nfsvers");
        snprintf(new_option, sizeof(new_option) - 1,
-                "nfsvers=%lu", nfs_server.pmap.pm_vers);
+                "vers=%lu", nfs_pmap->pm_vers);
        if (po_append(options, new_option) == PO_FAILED)
-               goto err;
+               return 0;
 
-       if (nfs_server.pmap.pm_prot == IPPROTO_TCP)
+       po_remove_all(options, "proto");
+       po_remove_all(options, "udp");
+       po_remove_all(options, "tcp");
+       switch (nfs_pmap->pm_prot) {
+       case IPPROTO_TCP:
                snprintf(new_option, sizeof(new_option) - 1,
                         "proto=tcp");
-       else
+               if (po_append(options, new_option) == PO_FAILED)
+                       return 0;
+               break;
+       case IPPROTO_UDP:
                snprintf(new_option, sizeof(new_option) - 1,
                         "proto=udp");
-       if (po_append(options, new_option) == PO_FAILED)
-               goto err;
+               if (po_append(options, new_option) == PO_FAILED)
+                       return 0;
+               break;
+       }
 
-       if (nfs_server.pmap.pm_port != NFS_PORT) {
+       po_remove_all(options, "port");
+       if (nfs_pmap->pm_port != NFS_PORT) {
                snprintf(new_option, sizeof(new_option) - 1,
-                        "port=%lu", nfs_server.pmap.pm_port);
+                        "port=%lu", nfs_pmap->pm_port);
                if (po_append(options, new_option) == PO_FAILED)
-                       goto err;
-
+                       return 0;
        }
 
-       if (mnt_server.pmap.pm_prot == IPPROTO_TCP)
+       po_remove_all(options, "mountvers");
+       snprintf(new_option, sizeof(new_option) - 1,
+                "mountvers=%lu", mnt_pmap->pm_vers);
+       if (po_append(options, new_option) == PO_FAILED)
+               return 0;
+
+       po_remove_all(options, "mountproto");
+       switch (mnt_pmap->pm_prot) {
+       case IPPROTO_TCP:
                snprintf(new_option, sizeof(new_option) - 1,
                         "mountproto=tcp");
-       else
+               if (po_append(options, new_option) == PO_FAILED)
+                       return 0;
+               break;
+       case IPPROTO_UDP:
                snprintf(new_option, sizeof(new_option) - 1,
                         "mountproto=udp");
-       if (po_append(options, new_option) == PO_FAILED)
-               goto err;
+               if (po_append(options, new_option) == PO_FAILED)
+                       return 0;
+               break;
+       }
 
+       po_remove_all(options, "mountport");
        snprintf(new_option, sizeof(new_option) - 1,
-                "mountport=%lu", mnt_server.pmap.pm_port);
+                "mountport=%lu", mnt_pmap->pm_port);
        if (po_append(options, new_option) == PO_FAILED)
-               goto err;
+               return 0;
 
-       errno = 0;
-       return options;
+       return 1;
+}
 
-err:
-       po_destroy(options);
-       return NULL;
+/*
+ * Reconstruct the mount option string based on a portmapper probe
+ * of the server.  Returns one if the server's portmapper returned
+ * something we can use, otherwise zero.
+ *
+ * To handle version and transport protocol fallback properly, we
+ * need to parse some of the mount options in order to set up a
+ * portmap probe.  Mount options that nfs_rewrite_pmap_mount_options()
+ * doesn't recognize are left alone.
+ *
+ * Returns TRUE if rewriting was successful; otherwise
+ * FALSE is returned if some failure occurred.
+ */
+static int
+nfs_rewrite_pmap_mount_options(struct mount_options *options)
+{
+       struct sockaddr_storage nfs_address;
+       struct sockaddr *nfs_saddr = (struct sockaddr *)&nfs_address;
+       socklen_t nfs_salen = sizeof(nfs_address);
+       struct pmap nfs_pmap;
+       struct sockaddr_storage mnt_address;
+       struct sockaddr *mnt_saddr = (struct sockaddr *)&mnt_address;
+       socklen_t mnt_salen = sizeof(mnt_address);
+       struct pmap mnt_pmap;
+       char *option;
+
+       /*
+        * Skip option negotiation for proto=rdma mounts.
+        */
+       option = po_get(options, "proto");
+       if (option && strcmp(option, "rdma") == 0)
+               goto out;
+
+       /*
+        * Extract just the options needed to contact server.
+        * Bail now if any of these have bad values.
+        */
+       if (!nfs_extract_server_addresses(options, nfs_saddr, &nfs_salen,
+                                               mnt_saddr, &mnt_salen)) {
+               errno = EINVAL;
+               return 0;
+       }
+       if (!nfs_options2pmap(options, &nfs_pmap, &mnt_pmap)) {
+               errno = EINVAL;
+               return 0;
+       }
+
+       /*
+        * The kernel NFS client doesn't support changing the RPC
+        * program number for these services, so force the value of
+        * these fields before probing the server's ports.
+        */
+       nfs_pmap.pm_prog = NFS_PROGRAM;
+       mnt_pmap.pm_prog = MOUNTPROG;
+
+       /*
+        * If the server's rpcbind service isn't available, we can't
+        * negotiate.  Bail now if we can't contact it.
+        */
+       if (!nfs_probe_bothports(mnt_saddr, mnt_salen, &mnt_pmap,
+                                nfs_saddr, nfs_salen, &nfs_pmap)) {
+               errno = ESPIPE;
+               return 0;
+       }
+
+       if (!nfs_construct_new_options(options, &nfs_pmap, &mnt_pmap)) {
+               errno = EINVAL;
+               return 0;
+       }
+
+out:
+       errno = 0;
+       return 1;
 }
 
 /*
  * Do the mount(2) system call.
  *
- * Returns 1 if successful, otherwise zero.
+ * Returns TRUE if successful, otherwise FALSE.
  * "errno" is set to reflect the individual error.
  */
-static int nfs_sys_mount(const struct nfsmount_info *mi, const char *type,
-                        const char *options)
+static int nfs_sys_mount(struct nfsmount_info *mi, struct mount_options *opts)
 {
+       char *options = NULL;
        int result;
 
-       result = mount(mi->spec, mi->node, type,
-                               mi->flags & ~(MS_USER|MS_USERS), options);
+       if (po_join(opts, &options) == PO_FAILED) {
+               errno = EIO;
+               return 0;
+       }
+
+       if (verbose)
+               printf(_("%s: trying text-based options '%s'\n"),
+                       progname, options);
+
+       if (mi->fake)
+               return 1;
+
+       result = mount(mi->spec, mi->node, mi->type,
+                       mi->flags & ~(MS_USER|MS_USERS), options);
        if (verbose && result) {
                int save = errno;
                nfs_error(_("%s: mount(2): %s"), progname, strerror(save));
@@ -490,127 +554,163 @@ static int nfs_sys_mount(const struct nfsmount_info *mi, const char *type,
 }
 
 /*
- * Retry an NFS mount that failed because the requested service isn't
- * available on the server.
- *
- * Returns 1 if successful.  Otherwise, returns zero.
- * "errno" is set to reflect the individual error.
- *
- * Side effect: If the retry is successful, both 'options' and
- * 'extra_opts' are updated to reflect the mount options that worked.
- * If the retry fails, 'options' and 'extra_opts' are left unchanged.
+ * For "-t nfs vers=2" or "-t nfs vers=3" mounts.
  */
-static int nfs_retry_nfs23mount(struct nfsmount_info *mi)
+static int nfs_try_mount_v3v2(struct nfsmount_info *mi)
 {
-       struct mount_options *retry_options;
-       char *retry_str = NULL;
-       char **extra_opts = mi->extra_opts;
+       struct mount_options *options = po_dup(mi->options);
+       int result = 0;
 
-       retry_options = nfs_rewrite_mount_options(*extra_opts);
-       if (!retry_options)
-               return 0;
-
-       if (po_join(retry_options, &retry_str) == PO_FAILED) {
-               po_destroy(retry_options);
-               errno = EIO;
-               return 0;
+       if (!options) {
+               errno = ENOMEM;
+               return result;
        }
 
-       if (verbose)
-               printf(_("%s: text-based options (retry): '%s'\n"),
-                       progname, retry_str);
+       if (!nfs_fix_mounthost_option(options)) {
+               errno = EINVAL;
+               goto out_fail;
+       }
+       if (!mi->fake && !nfs_verify_lock_option(options)) {
+               errno = EINVAL;
+               goto out_fail;
+       }
 
-       if (!nfs_sys_mount(mi, "nfs", retry_str)) {
-               po_destroy(retry_options);
-               free(retry_str);
-               return 0;
+       /*
+        * Options we negotiate below may be stale by the time this
+        * file system is unmounted.  In order to force umount.nfs
+        * to renegotiate with the server, only write the user-
+        * specified options, and not negotiated options, to /etc/mtab.
+        */
+       if (po_join(options, mi->extra_opts) == PO_FAILED) {
+               errno = ENOMEM;
+               goto out_fail;
        }
 
-       free(*extra_opts);
-       *extra_opts = retry_str;
-       po_replace(mi->options, retry_options);
-       return 1;
+       if (!nfs_rewrite_pmap_mount_options(options))
+               goto out_fail;
+
+       result = nfs_sys_mount(mi, options);
+
+out_fail:
+       po_destroy(options);
+       return result;
 }
 
 /*
- * Attempt an NFSv2/3 mount via a mount(2) system call.  If the kernel
- * claims the requested service isn't supported on the server, probe
- * the server to see what's supported, rewrite the mount options,
- * and retry the request.
- *
- * Returns 1 if successful.  Otherwise, returns zero.
- * "errno" is set to reflect the individual error.
- *
- * Side effect: If the retry is successful, both 'options' and
- * 'extra_opts' are updated to reflect the mount options that worked.
- * If the retry fails, 'options' and 'extra_opts' are left unchanged.
+ * For "-t nfs -o vers=4" or "-t nfs4" mounts.
  */
-static int nfs_try_nfs23mount(struct nfsmount_info *mi)
+static int nfs_try_mount_v4(struct nfsmount_info *mi)
 {
-       char **extra_opts = mi->extra_opts;
+       struct sockaddr *sap = (struct sockaddr *)&mi->address;
+       struct mount_options *options = po_dup(mi->options);
+       int result = 0;
 
-       if (po_join(mi->options, extra_opts) == PO_FAILED) {
-               errno = EIO;
-               return 0;
+       if (!options) {
+               errno = ENOMEM;
+               return result;
        }
 
-       if (verbose)
-               printf(_("%s: text-based options: '%s'\n"),
-                       progname, *extra_opts);
-
-       if (mi->fake)
-               return 1;
+       if (mi->version == 0) {
+               if (po_contains(options, "mounthost") ||
+                       po_contains(options, "mountaddr") ||
+                       po_contains(options, "mountvers") ||
+                       po_contains(options, "mountproto")) {
+               /*
+                * Since these mountd options are set assume version 3
+                * is wanted so error out with EPROTONOSUPPORT so the
+                * protocol negation starts with v3.
+                */
+                       errno = EPROTONOSUPPORT;
+                       goto out_fail;
+               }
+               if (po_append(options, "vers=4") == PO_FAILED) {
+                       errno = EINVAL;
+                       goto out_fail;
+               }
+       }
 
-       if (nfs_sys_mount(mi, "nfs", *extra_opts))
-               return 1;
+       if (!nfs_append_clientaddr_option(sap, mi->salen, options)) {
+               errno = EINVAL;
+               goto out_fail;
+       }
 
        /*
-        * The kernel returns EOPNOTSUPP if the RPC bind failed,
-        * and EPROTONOSUPPORT if the version isn't supported.
+        * Update option string to be recorded in /etc/mtab.
         */
-       if (errno != EOPNOTSUPP && errno != EPROTONOSUPPORT)
-               return 0;
+       if (po_join(options, mi->extra_opts) == PO_FAILED) {
+               errno = ENOMEM;
+               goto out_fail;
+       }
+
+       result = nfs_sys_mount(mi, options);
 
-       return nfs_retry_nfs23mount(mi);
+out_fail:
+       po_destroy(options);
+       return result;
 }
 
 /*
- * Attempt an NFS v4 mount via a mount(2) system call.
+ * This is a single pass through the fg/bg loop.
  *
- * Returns 1 if successful.  Otherwise, returns zero.
+ * Returns TRUE if successful, otherwise FALSE.
  * "errno" is set to reflect the individual error.
  */
-static int nfs_try_nfs4mount(struct nfsmount_info *mi)
+static int nfs_try_mount(struct nfsmount_info *mi)
 {
-       char **extra_opts = mi->extra_opts;
-
-       if (po_join(mi->options, extra_opts) == PO_FAILED) {
+       int result = 0;
+
+       switch (mi->version) {
+       case 0:
+               if (linux_version_code() > MAKE_VERSION(2, 6, 31)) {
+                       errno = 0;
+                       result = nfs_try_mount_v4(mi);
+                       if (errno != EPROTONOSUPPORT) {
+                               /* 
+                                * To deal with legacy Linux servers that don't
+                                * automatically export a pseudo root, retry
+                                * ENOENT errors using version 3
+                                */
+                               if (errno != ENOENT)
+                                       break;
+                       }
+               }
+       case 2:
+       case 3:
+               result = nfs_try_mount_v3v2(mi);
+               break;
+       case 4:
+               result = nfs_try_mount_v4(mi);
+               break;
+       default:
                errno = EIO;
-               return 0;
        }
 
-       if (verbose)
-               printf(_("%s: text-based options: '%s'\n"),
-                       progname, *extra_opts);
-
-       if (mi->fake)
-               return 1;
-
-       return nfs_sys_mount(mi, "nfs4", *extra_opts);
+       return result;
 }
 
 /*
- * Perform either an NFSv2/3 mount, or an NFSv4 mount system call.
+ * Distinguish between permanent and temporary errors.
  *
- * Returns 1 if successful.  Otherwise, returns zero.
- * "errno" is set to reflect the individual error.
+ * Basically, we retry if communication with the server has
+ * failed so far, but fail immediately if there is a local
+ * error (like a bad mount option).
+ *
+ * ESTALE is also a temporary error because some servers
+ * return ESTALE when a share is temporarily offline.
+ *
+ * Returns 1 if we should fail immediately, or 0 if we
+ * should retry.
  */
-static int nfs_try_mount(struct nfsmount_info *mi)
+static int nfs_is_permanent_error(int error)
 {
-       if (strncmp(mi->type, "nfs4", 4) == 0)
-               return nfs_try_nfs4mount(mi);
-       else
-               return nfs_try_nfs23mount(mi);
+       switch (error) {
+       case ESTALE:
+       case ETIMEDOUT:
+       case ECONNREFUSED:
+               return 0;       /* temporary */
+       default:
+               return 1;       /* permanent */
+       }
 }
 
 /*
@@ -745,7 +845,7 @@ static int nfsmount_start(struct nfsmount_info *mi)
        if (!nfs_validate_options(mi))
                return EX_FAIL;
 
-       if (po_rightmost(mi->options, nfs_background_opttbl) == 1)
+       if (po_rightmost(mi->options, nfs_background_opttbl) == 0)
                return nfsmount_bg(mi);
        else
                return nfsmount_fg(mi);
@@ -773,11 +873,6 @@ int nfsmount_string(const char *spec, const char *node, const char *type,
                .flags          = flags,
                .fake           = fake,
                .child          = child,
-#ifdef IPV6_SUPPORTED
-               .family         = AF_UNSPEC,    /* either IPv4 or v6 */
-#else
-               .family         = AF_INET,      /* only IPv4 */
-#endif
        };
        int retval = EX_FAIL;