5404 smbfs needs mmap support
Portions contributed by: Gordon Ross <gordon.w.ross@gmail.com>

@@ -879,49 +879,56 @@
                 *sbp = smi->smi_statvfsbuf;
         mutex_exit(&smi->smi_lock);
         return (error);
 }
 
-static kmutex_t smbfs_syncbusy;
-
 /*
  * Flush dirty smbfs files for file system vfsp.
  * If vfsp == NULL, all smbfs files are flushed.
  */
 /*ARGSUSED*/
 static int
 smbfs_sync(vfs_t *vfsp, short flag, cred_t *cr)
 {
+
         /*
-         * Cross-zone calls are OK here, since this translates to a
-         * VOP_PUTPAGE(B_ASYNC), which gets picked up by the right zone.
+         * SYNC_ATTR is used by fsflush() to force old filesystems like UFS
+         * to sync metadata, which they would otherwise cache indefinitely.
+         * Semantically, the only requirement is that the sync be initiated.
+         * Assume the server-side takes care of attribute sync.
          */
-        if (!(flag & SYNC_ATTR) && mutex_tryenter(&smbfs_syncbusy) != 0) {
-                smbfs_rflush(vfsp, cr);
-                mutex_exit(&smbfs_syncbusy);
+        if (flag & SYNC_ATTR)
+                return (0);
+
+        if (vfsp == NULL) {
+                /*
+                 * Flush ALL smbfs mounts in this zone.
+                 */
+                smbfs_flushall(cr);
+                return (0);
         }
 
+        smbfs_rflush(vfsp, cr);
+
         return (0);
 }
 
 /*
  * Initialization routine for VFS routines.  Should only be called once
  */
 int
 smbfs_vfsinit(void)
 {
-        mutex_init(&smbfs_syncbusy, NULL, MUTEX_DEFAULT, NULL);
         return (0);
 }
 
 /*
  * Shutdown routine for VFS routines.  Should only be called once
  */
 void
 smbfs_vfsfini(void)
 {
-        mutex_destroy(&smbfs_syncbusy);
 }
 
 void
 smbfs_freevfs(vfs_t *vfsp)
 {