diff --git a/components/dfs/dfs_v1/include/dfs_file.h b/components/dfs/dfs_v1/include/dfs_file.h
index e125fb25ac..26c74c8f16 100644
--- a/components/dfs/dfs_v1/include/dfs_file.h
+++ b/components/dfs/dfs_v1/include/dfs_file.h
@@ -63,6 +63,7 @@ struct dfs_file
     struct dfs_vnode *vnode;     /* file node struct */
     void *data;                  /* Specific fd data */
 };
+#define DFS_FILE_POS(dfs_file) ((dfs_file)->pos)
 
 #ifdef RT_USING_SMART
 struct dfs_mmap2_args
diff --git a/components/dfs/dfs_v2/filesystems/devfs/devfs.c b/components/dfs/dfs_v2/filesystems/devfs/devfs.c
index b2e75d06d8..7ebac59868 100644
--- a/components/dfs/dfs_v2/filesystems/devfs/devfs.c
+++ b/components/dfs/dfs_v2/filesystems/devfs/devfs.c
@@ -282,9 +282,7 @@ int dfs_devfs_ioctl(struct dfs_file *file, int cmd, void *args)
     {
         result = device->fops->ioctl(file, cmd, args);
     }
-    else if (device->ops)
-#else
-    if (device->ops)
+    else
 #endif /* RT_USING_POSIX_DEVIO */
     {
         result = rt_device_control(device, cmd, args);
@@ -312,9 +310,7 @@ ssize_t dfs_devfs_read(struct dfs_file *file, void *buf, size_t count, off_t *po
     {
         result = device->fops->read(file, buf, count, pos);
     }
-    else if (device->ops)
-#else
-    if (device->ops)
+    else
 #endif /* RT_USING_POSIX_DEVIO */
     {
         /* read device data */
@@ -344,9 +340,7 @@ ssize_t dfs_devfs_write(struct dfs_file *file, const void *buf, size_t count, of
     {
         result = device->fops->write(file, buf, count, pos);
     }
-    else if (device->ops)
-#else
-    if (device->ops)
+    else
 #endif /* RT_USING_POSIX_DEVIO */
     {
         /* read device data */
@@ -375,9 +369,7 @@ int dfs_devfs_close(struct dfs_file *file)
         {
             result = device->fops->close(file);
         }
-        else if (device->ops)
-#else
-        if (device->ops)
+        else
 #endif /* RT_USING_POSIX_DEVIO */
         {
             /* close device handler */
@@ -417,9 +409,7 @@ int dfs_devfs_open(struct dfs_file *file)
                     return RT_EOK;
                 }
             }
-            else if (device->ops)
-#else
-            if (device->ops)
+            else
 #endif /* RT_USING_POSIX_DEVIO */
             {
                 result = rt_device_open(device, RT_DEVICE_OFLAG_RDWR);
diff --git a/components/dfs/dfs_v2/include/dfs_file.h b/components/dfs/dfs_v2/include/dfs_file.h
index 9a47198e4d..d62aec1e89 100644
--- a/components/dfs/dfs_v2/include/dfs_file.h
+++ b/components/dfs/dfs_v2/include/dfs_file.h
@@ -101,6 +101,7 @@ struct dfs_file
 
     void *data;
 };
+#define DFS_FILE_POS(dfs_file) ((dfs_file)->fpos)
 
 /* file is open for reading */
 #define FMODE_READ 0x1
diff --git a/components/drivers/core/device.c b/components/drivers/core/device.c
index e59b769733..30c8adfd60 100644
--- a/components/drivers/core/device.c
+++ b/components/drivers/core/device.c
@@ -32,12 +32,12 @@
 #ifdef RT_USING_DEVICE
 
 #ifdef RT_USING_DEVICE_OPS
-#define device_init     (dev->ops->init)
-#define device_open     (dev->ops->open)
-#define device_close    (dev->ops->close)
-#define device_read     (dev->ops->read)
-#define device_write    (dev->ops->write)
-#define device_control  (dev->ops->control)
+#define device_init     (dev->ops ? dev->ops->init : RT_NULL)
+#define device_open     (dev->ops ? dev->ops->open : RT_NULL)
+#define device_close    (dev->ops ? dev->ops->close : RT_NULL)
+#define device_read     (dev->ops ? dev->ops->read : RT_NULL)
+#define device_write    (dev->ops ? dev->ops->write : RT_NULL)
+#define device_control  (dev->ops ? dev->ops->control : RT_NULL)
 #else
 #define device_init     (dev->init)
 #define device_open     (dev->open)
diff --git a/components/fal/src/fal_rtt.c b/components/fal/src/fal_rtt.c
index 89dcdf4722..bfbe66785b 100644
--- a/components/fal/src/fal_rtt.c
+++ b/components/fal/src/fal_rtt.c
@@ -424,7 +424,7 @@ static int char_dev_fopen(struct dfs_file *fd)
     default:
         break;
     }
-    fd->pos = 0;
+    DFS_FILE_POS(fd) = 0;
 
     return RT_EOK;
 }
@@ -436,15 +436,15 @@ static int char_dev_fread(struct dfs_file *fd, void *buf, size_t count)
 
     assert(part != RT_NULL);
 
-    if (fd->pos + count > part->fal_part->len)
-        count = part->fal_part->len - fd->pos;
+    if (DFS_FILE_POS(fd) + count > part->fal_part->len)
+        count = part->fal_part->len - DFS_FILE_POS(fd);
 
-    ret = fal_partition_read(part->fal_part, fd->pos, buf, count);
+    ret = fal_partition_read(part->fal_part, DFS_FILE_POS(fd), buf, count);
 
     if (ret != (int)(count))
         return 0;
 
-    fd->pos += ret;
+    DFS_FILE_POS(fd) += ret;
 
     return ret;
 }
@@ -456,15 +456,15 @@ static int char_dev_fwrite(struct dfs_file *fd, const void *buf, size_t count)
 
     assert(part != RT_NULL);
 
-    if (fd->pos + count > part->fal_part->len)
-        count = part->fal_part->len - fd->pos;
+    if (DFS_FILE_POS(fd) + count > part->fal_part->len)
+        count = part->fal_part->len - DFS_FILE_POS(fd);
 
-    ret = fal_partition_write(part->fal_part, fd->pos, buf, count);
+    ret = fal_partition_write(part->fal_part, DFS_FILE_POS(fd), buf, count);
 
     if (ret != (int) count)
         return 0;
 
-    fd->pos += ret;
+    DFS_FILE_POS(fd) += ret;
 
     return ret;
 }