OS-4043 tmpfs should support gigabyte sizes
OS-4044 tmpfs should support "mode" option
Reviewed by: Robert Mustacchi <rm@joyent.com>
Reviewed by: Patrick Mooney <patrick.mooney@joyent.com>

@@ -18,11 +18,11 @@
  *
  * CDDL HEADER END
  */
 /*
  * Copyright (c) 1990, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2011, Joyent, Inc. All rights reserved.
+ * Copyright 2015 Joyent, Inc.
  */
 
 #include <sys/types.h>
 #include <sys/param.h>
 #include <sys/sysmacros.h>

@@ -89,11 +89,12 @@
 
 static mntopt_t tmpfs_options[] = {
         /* Option name          Cancel Opt      Arg     Flags           Data */
         { MNTOPT_XATTR,         xattr_cancel,   NULL,   MO_DEFAULT,     NULL},
         { MNTOPT_NOXATTR,       noxattr_cancel, NULL,   NULL,           NULL},
-        { "size",               NULL,           "0",    MO_HASVALUE,    NULL}
+        { "size",               NULL,           "0",    MO_HASVALUE,    NULL},
+        { "mode",               NULL,           NULL,   MO_HASVALUE,    NULL}
 };
 
 
 static mntopts_t tmpfs_proto_opttbl = {
         sizeof (tmpfs_options) / sizeof (mntopt_t),

@@ -225,26 +226,23 @@
         mutex_init(&tmpfs_minor_lock, NULL, MUTEX_DEFAULT, NULL);
         return (0);
 }
 
 static int
-tmp_mount(
-        struct vfs *vfsp,
-        struct vnode *mvp,
-        struct mounta *uap,
-        struct cred *cr)
+tmp_mount(vfs_t *vfsp, vnode_t *mvp, struct mounta *uap, cred_t *cr)
 {
         struct tmount *tm = NULL;
         struct tmpnode *tp;
         struct pathname dpn;
         int error;
         pgcnt_t anonmax;
         struct vattr rattr;
         int got_attrs;
+        boolean_t mode_arg = B_FALSE;
+        mode_t root_mode = 0777;
+        char *argstr;
 
-        char *sizestr;
-
         if ((error = secpolicy_fs_mount(cr, mvp, vfsp)) != 0)
                 return (error);
 
         if (mvp->v_type != VDIR)
                 return (ENOTDIR);

@@ -274,17 +272,28 @@
 
         /*
          * tm_anonmax is set according to the mount arguments
          * if any.  Otherwise, it is set to a maximum value.
          */
-        if (vfs_optionisset(vfsp, "size", &sizestr)) {
-                if ((error = tmp_convnum(sizestr, &anonmax)) != 0)
+        if (vfs_optionisset(vfsp, "size", &argstr)) {
+                if ((error = tmp_convnum(argstr, &anonmax)) != 0)
                         goto out;
         } else {
                 anonmax = ULONG_MAX;
         }
 
+        /*
+         * The "mode" mount argument allows the operator to override the
+         * permissions of the root of the tmpfs mount.
+         */
+        if (vfs_optionisset(vfsp, "mode", &argstr)) {
+                if ((error = tmp_convmode(argstr, &root_mode)) != 0) {
+                        goto out;
+                }
+                mode_arg = B_TRUE;
+        }
+
         if (error = pn_get(uap->dir,
             (uap->flags & MS_SYSSPACE) ? UIO_SYSSPACE : UIO_USERSPACE, &dpn))
                 goto out;
 
         if (uap->flags & MS_REMOUNT) {

@@ -339,11 +348,11 @@
 
         /*
          * allocate and initialize root tmpnode structure
          */
         bzero(&rattr, sizeof (struct vattr));
-        rattr.va_mode = (mode_t)(S_IFDIR | 0777);       /* XXX modes */
+        rattr.va_mode = (mode_t)(S_IFDIR | root_mode);
         rattr.va_type = VDIR;
         rattr.va_rdev = 0;
         tp = tmp_memalloc(sizeof (struct tmpnode), TMP_MUSTHAVE);
         tmpnode_init(tm, tp, &rattr, cr);
 

@@ -359,11 +368,18 @@
         /*
          * If the getattr succeeded, use its results.  Otherwise allow
          * the previously set hardwired defaults to prevail.
          */
         if (got_attrs == 0) {
+                if (!mode_arg) {
+                        /*
+                         * Only use the underlying mount point for the
+                         * mode if the "mode" mount argument was not
+                         * provided.
+                         */
                 tp->tn_mode = rattr.va_mode;
+                }
                 tp->tn_uid = rattr.va_uid;
                 tp->tn_gid = rattr.va_gid;
         }
 
         /*