1.修复sd卡热插拔内存泄露的bug

2.dfs增加函数，配合实现sd卡热插拔自动挂载卸载文件系统

components/dfs/src/dfs_fs.c

@@ -508,7 +508,7 @@ int dfs_mount_table(void)
                       mount_table[index].rwflag,
                       mount_table[index].data) != 0)
         {
-            rt_kprintf("mount fs[%s] on %s failed.\n", mount_table[index].filesystemtype,
+            LOG_E("mount fs[%s] on %s failed.\n", mount_table[index].filesystemtype,
                        mount_table[index].path);
             return -RT_ERROR;
         }
@@ -518,6 +518,43 @@ int dfs_mount_table(void)
     return 0;
 }
 INIT_ENV_EXPORT(dfs_mount_table);
+
+int dfs_mount_device(rt_device_t dev)
+{
+  int index = 0;
+  
+  if(dev == RT_NULL) {
+    rt_kprintf("the device is NULL to be mounted.\n");
+    return -RT_ERROR;
+  }
+  
+  while (1)
+  {
+    if (mount_table[index].path == NULL) break;
+    
+    if(strcmp(mount_table[index].device_name, dev->parent.name) == 0) {
+      if (dfs_mount(mount_table[index].device_name,
+                    mount_table[index].path,
+                    mount_table[index].filesystemtype,
+                    mount_table[index].rwflag,
+                    mount_table[index].data) != 0)
+      {
+        LOG_E("mount fs[%s] device[%s] to %s failed.\n", mount_table[index].filesystemtype, dev->parent.name,
+                   mount_table[index].path);
+        return -RT_ERROR;
+      } else {
+        LOG_D("mount fs[%s] device[%s] to %s ok.\n", mount_table[index].filesystemtype, dev->parent.name,
+                   mount_table[index].path);
+        return RT_EOK;
+      }
+    }
+    
+    index ++;
+  }
+  
+  rt_kprintf("can't find device:%s to be mounted.\n", dev->parent.name);
+  return -RT_ERROR;
+}
 #endif
 
 #ifdef RT_USING_FINSH

components/dfs/src/poll.c

@@ -19,6 +19,8 @@
 #include <dfs_posix.h>
 #include <dfs_poll.h>
 
+#ifdef RT_USING_POSIX
+
 struct rt_poll_node;
 
 struct rt_poll_table
@@ -214,3 +216,4 @@ int poll(struct pollfd *fds, nfds_t nfds, int timeout)
     return num;
 }
 
+#endif 

components/dfs/src/select.c

@@ -14,6 +14,8 @@
 #include <dfs_poll.h>
 #include <dfs_select.h>
 
+#ifdef RT_USING_POSIX
+
 static void fdszero(fd_set *set, int nfds)
 {
     fd_mask *m;
@@ -178,3 +180,4 @@ int select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struc
     return ret;
 }
 
+#endif