diff --git a/components/dfs/filesystems/devfs/devfs.c b/components/dfs/filesystems/devfs/devfs.c
index 2a8e78df5e..45195f3c29 100644
--- a/components/dfs/filesystems/devfs/devfs.c
+++ b/components/dfs/filesystems/devfs/devfs.c
@@ -248,6 +248,7 @@ int dfs_device_fs_getdents(struct dfs_fd* file, struct dirent* dirp, rt_uint32_t
 static const struct dfs_filesystem_operation _device_fs = 
 {
 	"devfs",
+	DFS_FS_FLAG_DEFAULT,
 	dfs_device_fs_mount,
 	RT_NULL,
 	RT_NULL,
diff --git a/components/dfs/filesystems/elmfat/dfs_elm.c b/components/dfs/filesystems/elmfat/dfs_elm.c
index 1beea7bbf5..d4f1dfc878 100644
--- a/components/dfs/filesystems/elmfat/dfs_elm.c
+++ b/components/dfs/filesystems/elmfat/dfs_elm.c
@@ -647,6 +647,7 @@ int dfs_elm_stat(struct dfs_filesystem *fs, const char *path, struct stat *st)
 static const struct dfs_filesystem_operation dfs_elm =
 {
 	"elm",
+	DFS_FS_FLAG_DEFAULT,
 	dfs_elm_mount,
 	dfs_elm_unmount,
 	dfs_elm_mkfs,
diff --git a/components/dfs/filesystems/nfs/dfs_nfs.c b/components/dfs/filesystems/nfs/dfs_nfs.c
index 528d4d910e..cbfdd128e0 100644
--- a/components/dfs/filesystems/nfs/dfs_nfs.c
+++ b/components/dfs/filesystems/nfs/dfs_nfs.c
@@ -1056,7 +1056,8 @@ int nfs_getdents(struct dfs_fd *file, struct dirent *dirp, rt_uint32_t count)
 
 static const struct dfs_filesystem_operation _nfs = 
 {
-	"nfs", 
+	"nfs",
+	DFS_FS_FLAG_DEFAULT,	
 	nfs_mount,
 	nfs_unmount,
 	RT_NULL, /* mkfs */
diff --git a/components/dfs/filesystems/romfs/dfs_romfs.c b/components/dfs/filesystems/romfs/dfs_romfs.c
index 760593b58c..d21c336f19 100644
--- a/components/dfs/filesystems/romfs/dfs_romfs.c
+++ b/components/dfs/filesystems/romfs/dfs_romfs.c
@@ -1,291 +1,292 @@
-/*
- * File      : dfs_romfs.c
- * This file is part of Device File System in RT-Thread RTOS
- * COPYRIGHT (C) 2004-2011, RT-Thread Development Team
- *
- * The license and distribution terms for this file may be
- * found in the file LICENSE in this distribution or at
- * http://www.rt-thread.org/license/LICENSE.
- *
- * Change Logs:
- * Date           Author       Notes
- */
-
-#include <rtthread.h>
-#include <dfs.h>
-#include <dfs_fs.h>
-#include "dfs_romfs.h"
-
-int dfs_romfs_mount(struct dfs_filesystem *fs, unsigned long rwflag, const void *data)
-{
-	struct romfs_dirent *root_dirent;
-
-	if (data == RT_NULL)
-		return -DFS_STATUS_EIO;
-
-	root_dirent = (struct romfs_dirent *)data;
-	fs->data = root_dirent;
-
-	return DFS_STATUS_OK;
-}
-
-int dfs_romfs_unmount(struct dfs_filesystem *fs)
-{
-	return DFS_STATUS_OK;
-}
-
-int dfs_romfs_ioctl(struct dfs_fd *file, int cmd, void *args)
-{
-	return -DFS_STATUS_EIO;
-}
-
-struct romfs_dirent *dfs_romfs_lookup(struct romfs_dirent *root_dirent, const char *path, rt_size_t *size)
-{
-	rt_size_t index, found;
-	const char *subpath, *subpath_end;
-	struct romfs_dirent *dirent;
-	rt_size_t dirent_size;
-
-	if (path[0] == '/' && path[1] == '\0') 
-	{
-		*size = root_dirent->size;
-		return root_dirent;
-	}
-
-	/* goto root directy entries */
-	dirent = (struct romfs_dirent *)root_dirent->data;
-	dirent_size = root_dirent->size;
-
-	/* get the end position of this subpath */
-	subpath_end = path;
-	/* skip /// */
-	while (*subpath_end && *subpath_end == '/')
-		subpath_end ++;
-	subpath = subpath_end;
-	while ((*subpath_end != '/') && *subpath_end)
-		subpath_end ++;
-
-	while (dirent != RT_NULL)
-	{
-		found = 0;
-		
-		/* search in folder */
-		for (index = 0; index < dirent_size; index ++)
-		{
-			if (rt_strncmp(dirent[index].name, subpath, (subpath_end - subpath)) == 0)
-			{
-				dirent_size = dirent[index].size;
-
-				/* skip /// */
-				while (*subpath_end && *subpath_end == '/')
-					subpath_end ++;
-				subpath = subpath_end;
-				while ((*subpath_end != '/') && *subpath_end)
-					subpath_end ++;
-
-				if (!(*subpath))
-				{
-					*size = dirent_size;
-					return &dirent[index];
-				}
-
-				if (dirent[index].type == ROMFS_DIRENT_DIR)
-				{
-					/* enter directory */
-					dirent = (struct romfs_dirent*)dirent[index].data;
-					found = 1;
-					break;
-				}
-				else 
-				{
-					/* return file dirent */
-					if (subpath != RT_NULL)
-						break; /* not the end of path */
-					
-					return &dirent[index];
-				}
-			}
-		}
-
-		if (!found)
-			break; /* not found */
-	}
-
-	/* not found */
-	return RT_NULL;
-}
-
-int dfs_romfs_read(struct dfs_fd *file, void *buf, rt_size_t count)
-{
-	rt_size_t length;
-	struct romfs_dirent *dirent;
-
-	dirent = (struct romfs_dirent *)file->data;
-	RT_ASSERT(dirent != RT_NULL);
-
-	if (count < file->size - file->pos)
-		length = count;
-	else
-		length = file->size - file->pos;
-
-	if (length > 0)
-		memcpy(buf, &(dirent->data[file->pos]), length);
-
-	/* update file current position */
-	file->pos += length;
-
-	return length;
-}
-
-int dfs_romfs_lseek(struct dfs_fd *file, rt_off_t offset)
-{
-	if (offset <= file->size)
-	{
-		file->pos = offset;
-		return file->pos;
-	}
-
-	return -DFS_STATUS_EIO;
-}
-
-int dfs_romfs_close(struct dfs_fd *file)
-{
-	file->data = RT_NULL;
-	return DFS_STATUS_OK;
-}
-
-int dfs_romfs_open(struct dfs_fd *file)
-{
-	rt_size_t size;
-	struct romfs_dirent *dirent;
-	struct romfs_dirent *root_dirent;
-
-	root_dirent = (struct romfs_dirent *)file->fs->data;
-
-	if (file->flags & (DFS_O_CREAT | DFS_O_WRONLY | DFS_O_APPEND | DFS_O_TRUNC | DFS_O_RDWR))
-		return -DFS_STATUS_EINVAL;
-
-	dirent = dfs_romfs_lookup(root_dirent, file->path, &size);
-	if (dirent == RT_NULL)
-		return -DFS_STATUS_ENOENT;
-
-	/* entry is a directory file type */
-	if (dirent->type == ROMFS_DIRENT_DIR)
-	{
-		if (!(file->flags & DFS_O_DIRECTORY))
-			return -DFS_STATUS_ENOENT;
-	}
-	else
-	{
-		/* entry is a file, but open it as a directory */
-		if (file->flags & DFS_O_DIRECTORY)
-			return -DFS_STATUS_ENOENT;
-	}
-
-	file->data = dirent;
-	file->size = size;
-	file->pos = 0;
-
-	return DFS_STATUS_OK;
-}
-
-int dfs_romfs_stat(struct dfs_filesystem *fs, const char *path, struct stat *st)
-{
-	rt_size_t size;
-	struct romfs_dirent *dirent;
-	struct romfs_dirent *root_dirent;
-
-	root_dirent = (struct romfs_dirent *)fs->data;
-	dirent = dfs_romfs_lookup(root_dirent, path, &size);
-
-	if (dirent == RT_NULL)
-		return -DFS_STATUS_ENOENT;
-
-	st->st_dev = 0;
-	st->st_mode = DFS_S_IFREG | DFS_S_IRUSR | DFS_S_IRGRP | DFS_S_IROTH |
-	DFS_S_IWUSR | DFS_S_IWGRP | DFS_S_IWOTH;
-
-	if (dirent->type == ROMFS_DIRENT_DIR)
-	{
-		st->st_mode &= ~DFS_S_IFREG;
-		st->st_mode |= DFS_S_IFDIR | DFS_S_IXUSR | DFS_S_IXGRP | DFS_S_IXOTH;
-	}
-
-	st->st_size = dirent->size;
-	st->st_mtime = 0;
-	st->st_blksize = 512;
-
-	return DFS_STATUS_OK;
-}
-
-int dfs_romfs_getdents(struct dfs_fd *file, struct dirent *dirp, rt_uint32_t count)
-{
-	rt_size_t index;
-	const char *name;
-	struct dirent *d;
-	struct romfs_dirent *dirent, *sub_dirent;
-
-	dirent = (struct romfs_dirent *)file->data;
-	RT_ASSERT(dirent->type == ROMFS_DIRENT_DIR);
-
-	/* enter directory */
-	dirent = (struct romfs_dirent *)dirent->data;
-	
-	/* make integer count */
-	count = (count / sizeof(struct dirent));
-	if (count == 0)
-		return -DFS_STATUS_EINVAL;
-	
-	index = 0;
-	for (index = 0; index < count && file->pos < file->size; index ++)
-	{
-		d = dirp + index;
-
-		sub_dirent = &dirent[file->pos];
-		name = sub_dirent->name;
-
-		/* fill dirent */
-		if (sub_dirent->type == ROMFS_DIRENT_DIR)
-			d->d_type = DFS_DT_DIR;
-		else
-			d->d_type = DFS_DT_REG;
-
-		d->d_namlen = rt_strlen(name);
-		d->d_reclen = (rt_uint16_t)sizeof(struct dirent);
-		rt_strncpy(d->d_name, name, rt_strlen(name) + 1);
-
-		/* move to next position */
-		++ file->pos; 
-	}
-
-	return index * sizeof(struct dirent);
-}
-
-static const struct dfs_filesystem_operation _romfs = 
-{
-	"rom",
-	dfs_romfs_mount,
-	dfs_romfs_unmount,
-	RT_NULL,
-	RT_NULL,
-
-	dfs_romfs_open,
-	dfs_romfs_close,
-	dfs_romfs_ioctl,
-	dfs_romfs_read,
-	RT_NULL,
-	RT_NULL,
-	dfs_romfs_lseek,
-	dfs_romfs_getdents,
-	RT_NULL,
-	dfs_romfs_stat,
-	RT_NULL,
-};
-
-int dfs_romfs_init(void)
-{
-    /* register rom file system */
-    dfs_register(&_romfs);
-	return 0;
-}
-
+/*
+ * File      : dfs_romfs.c
+ * This file is part of Device File System in RT-Thread RTOS
+ * COPYRIGHT (C) 2004-2011, RT-Thread Development Team
+ *
+ * The license and distribution terms for this file may be
+ * found in the file LICENSE in this distribution or at
+ * http://www.rt-thread.org/license/LICENSE.
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ */
+
+#include <rtthread.h>
+#include <dfs.h>
+#include <dfs_fs.h>
+#include "dfs_romfs.h"
+
+int dfs_romfs_mount(struct dfs_filesystem *fs, unsigned long rwflag, const void *data)
+{
+	struct romfs_dirent *root_dirent;
+
+	if (data == RT_NULL)
+		return -DFS_STATUS_EIO;
+
+	root_dirent = (struct romfs_dirent *)data;
+	fs->data = root_dirent;
+
+	return DFS_STATUS_OK;
+}
+
+int dfs_romfs_unmount(struct dfs_filesystem *fs)
+{
+	return DFS_STATUS_OK;
+}
+
+int dfs_romfs_ioctl(struct dfs_fd *file, int cmd, void *args)
+{
+	return -DFS_STATUS_EIO;
+}
+
+struct romfs_dirent *dfs_romfs_lookup(struct romfs_dirent *root_dirent, const char *path, rt_size_t *size)
+{
+	rt_size_t index, found;
+	const char *subpath, *subpath_end;
+	struct romfs_dirent *dirent;
+	rt_size_t dirent_size;
+
+	if (path[0] == '/' && path[1] == '\0') 
+	{
+		*size = root_dirent->size;
+		return root_dirent;
+	}
+
+	/* goto root directy entries */
+	dirent = (struct romfs_dirent *)root_dirent->data;
+	dirent_size = root_dirent->size;
+
+	/* get the end position of this subpath */
+	subpath_end = path;
+	/* skip /// */
+	while (*subpath_end && *subpath_end == '/')
+		subpath_end ++;
+	subpath = subpath_end;
+	while ((*subpath_end != '/') && *subpath_end)
+		subpath_end ++;
+
+	while (dirent != RT_NULL)
+	{
+		found = 0;
+		
+		/* search in folder */
+		for (index = 0; index < dirent_size; index ++)
+		{
+			if (rt_strncmp(dirent[index].name, subpath, (subpath_end - subpath)) == 0)
+			{
+				dirent_size = dirent[index].size;
+
+				/* skip /// */
+				while (*subpath_end && *subpath_end == '/')
+					subpath_end ++;
+				subpath = subpath_end;
+				while ((*subpath_end != '/') && *subpath_end)
+					subpath_end ++;
+
+				if (!(*subpath))
+				{
+					*size = dirent_size;
+					return &dirent[index];
+				}
+
+				if (dirent[index].type == ROMFS_DIRENT_DIR)
+				{
+					/* enter directory */
+					dirent = (struct romfs_dirent*)dirent[index].data;
+					found = 1;
+					break;
+				}
+				else 
+				{
+					/* return file dirent */
+					if (subpath != RT_NULL)
+						break; /* not the end of path */
+					
+					return &dirent[index];
+				}
+			}
+		}
+
+		if (!found)
+			break; /* not found */
+	}
+
+	/* not found */
+	return RT_NULL;
+}
+
+int dfs_romfs_read(struct dfs_fd *file, void *buf, rt_size_t count)
+{
+	rt_size_t length;
+	struct romfs_dirent *dirent;
+
+	dirent = (struct romfs_dirent *)file->data;
+	RT_ASSERT(dirent != RT_NULL);
+
+	if (count < file->size - file->pos)
+		length = count;
+	else
+		length = file->size - file->pos;
+
+	if (length > 0)
+		memcpy(buf, &(dirent->data[file->pos]), length);
+
+	/* update file current position */
+	file->pos += length;
+
+	return length;
+}
+
+int dfs_romfs_lseek(struct dfs_fd *file, rt_off_t offset)
+{
+	if (offset <= file->size)
+	{
+		file->pos = offset;
+		return file->pos;
+	}
+
+	return -DFS_STATUS_EIO;
+}
+
+int dfs_romfs_close(struct dfs_fd *file)
+{
+	file->data = RT_NULL;
+	return DFS_STATUS_OK;
+}
+
+int dfs_romfs_open(struct dfs_fd *file)
+{
+	rt_size_t size;
+	struct romfs_dirent *dirent;
+	struct romfs_dirent *root_dirent;
+
+	root_dirent = (struct romfs_dirent *)file->fs->data;
+
+	if (file->flags & (DFS_O_CREAT | DFS_O_WRONLY | DFS_O_APPEND | DFS_O_TRUNC | DFS_O_RDWR))
+		return -DFS_STATUS_EINVAL;
+
+	dirent = dfs_romfs_lookup(root_dirent, file->path, &size);
+	if (dirent == RT_NULL)
+		return -DFS_STATUS_ENOENT;
+
+	/* entry is a directory file type */
+	if (dirent->type == ROMFS_DIRENT_DIR)
+	{
+		if (!(file->flags & DFS_O_DIRECTORY))
+			return -DFS_STATUS_ENOENT;
+	}
+	else
+	{
+		/* entry is a file, but open it as a directory */
+		if (file->flags & DFS_O_DIRECTORY)
+			return -DFS_STATUS_ENOENT;
+	}
+
+	file->data = dirent;
+	file->size = size;
+	file->pos = 0;
+
+	return DFS_STATUS_OK;
+}
+
+int dfs_romfs_stat(struct dfs_filesystem *fs, const char *path, struct stat *st)
+{
+	rt_size_t size;
+	struct romfs_dirent *dirent;
+	struct romfs_dirent *root_dirent;
+
+	root_dirent = (struct romfs_dirent *)fs->data;
+	dirent = dfs_romfs_lookup(root_dirent, path, &size);
+
+	if (dirent == RT_NULL)
+		return -DFS_STATUS_ENOENT;
+
+	st->st_dev = 0;
+	st->st_mode = DFS_S_IFREG | DFS_S_IRUSR | DFS_S_IRGRP | DFS_S_IROTH |
+	DFS_S_IWUSR | DFS_S_IWGRP | DFS_S_IWOTH;
+
+	if (dirent->type == ROMFS_DIRENT_DIR)
+	{
+		st->st_mode &= ~DFS_S_IFREG;
+		st->st_mode |= DFS_S_IFDIR | DFS_S_IXUSR | DFS_S_IXGRP | DFS_S_IXOTH;
+	}
+
+	st->st_size = dirent->size;
+	st->st_mtime = 0;
+	st->st_blksize = 512;
+
+	return DFS_STATUS_OK;
+}
+
+int dfs_romfs_getdents(struct dfs_fd *file, struct dirent *dirp, rt_uint32_t count)
+{
+	rt_size_t index;
+	const char *name;
+	struct dirent *d;
+	struct romfs_dirent *dirent, *sub_dirent;
+
+	dirent = (struct romfs_dirent *)file->data;
+	RT_ASSERT(dirent->type == ROMFS_DIRENT_DIR);
+
+	/* enter directory */
+	dirent = (struct romfs_dirent *)dirent->data;
+	
+	/* make integer count */
+	count = (count / sizeof(struct dirent));
+	if (count == 0)
+		return -DFS_STATUS_EINVAL;
+	
+	index = 0;
+	for (index = 0; index < count && file->pos < file->size; index ++)
+	{
+		d = dirp + index;
+
+		sub_dirent = &dirent[file->pos];
+		name = sub_dirent->name;
+
+		/* fill dirent */
+		if (sub_dirent->type == ROMFS_DIRENT_DIR)
+			d->d_type = DFS_DT_DIR;
+		else
+			d->d_type = DFS_DT_REG;
+
+		d->d_namlen = rt_strlen(name);
+		d->d_reclen = (rt_uint16_t)sizeof(struct dirent);
+		rt_strncpy(d->d_name, name, rt_strlen(name) + 1);
+
+		/* move to next position */
+		++ file->pos; 
+	}
+
+	return index * sizeof(struct dirent);
+}
+
+static const struct dfs_filesystem_operation _romfs = 
+{
+	"rom",
+	DFS_FS_FLAG_DEFAULT,
+	dfs_romfs_mount,
+	dfs_romfs_unmount,
+	RT_NULL,
+	RT_NULL,
+
+	dfs_romfs_open,
+	dfs_romfs_close,
+	dfs_romfs_ioctl,
+	dfs_romfs_read,
+	RT_NULL,
+	RT_NULL,
+	dfs_romfs_lseek,
+	dfs_romfs_getdents,
+	RT_NULL,
+	dfs_romfs_stat,
+	RT_NULL,
+};
+
+int dfs_romfs_init(void)
+{
+    /* register rom file system */
+    dfs_register(&_romfs);
+	return 0;
+}
+
diff --git a/components/dfs/filesystems/skeleton/skeleton.c b/components/dfs/filesystems/skeleton/skeleton.c
index 2d11b0b1e1..ed2791ad4a 100644
--- a/components/dfs/filesystems/skeleton/skeleton.c
+++ b/components/dfs/filesystems/skeleton/skeleton.c
@@ -55,6 +55,7 @@ int dfs_skt_getdents(struct dfs_fd* file, struct dirent* dirp, rt_uint32_t count
 static const struct dfs_filesystem_operation _skt_fs = 
 {
 	"skt",
+	DFS_FS_FLAG_DEFAULT,
 	dfs_skt_mount,
 	dfs_skt_unmount,
 	RT_NULL,
diff --git a/components/dfs/filesystems/uffs/dfs_uffs.c b/components/dfs/filesystems/uffs/dfs_uffs.c
index 4c2a084a78..1b35590c06 100644
--- a/components/dfs/filesystems/uffs/dfs_uffs.c
+++ b/components/dfs/filesystems/uffs/dfs_uffs.c
@@ -1,354 +1,355 @@
-#include <rtthread.h>   
-#include <dfs_def.h>   
-#include <dfs_fs.h>
-#include "uffs/uffs_fs.h"
-#include "uffs/uffs_mtb.h"
-#include "uffs/uffs_fd.h"
-#include "uffs_ext.h"
-
-/* mount and unmount file system */ 
-int dfs_uffs_mount(struct dfs_filesystem* fs, unsigned long rwflag, const void* data)   
-{
-	return ((uffs_InitMountTable() == U_SUCC) ? 0 : -1);   
-}      
-
-int dfs_uffs_unmount(struct dfs_filesystem* fs)   
-{
-	uffs_ReleaseObjectBuf();
-	return uffs_ReleaseMountTable();  
-}      
-
-int dfs_uffs_mkfs(const char* device_name)   
-{        
-	return uffs_format(NULL);   
-}      
-
-int dfs_uffs_statfs(struct dfs_filesystem* fs, struct statfs *buf)   
-{
-	int ret = U_SUCC;
-	uffs_MountTable *entry = (uffs_MountTable*)(fs->dev_id->user_data);
-	struct uffs_StorageAttrSt *attr = entry->dev->attr;
-
+#include <rtthread.h>   
+#include <dfs_def.h>   
+#include <dfs_fs.h>
+#include "uffs/uffs_fs.h"
+#include "uffs/uffs_mtb.h"
+#include "uffs/uffs_fd.h"
+#include "uffs_ext.h"
+
+/* mount and unmount file system */ 
+int dfs_uffs_mount(struct dfs_filesystem* fs, unsigned long rwflag, const void* data)   
+{
+	return ((uffs_InitMountTable() == U_SUCC) ? 0 : -1);   
+}      
+
+int dfs_uffs_unmount(struct dfs_filesystem* fs)   
+{
+	uffs_ReleaseObjectBuf();
+	return uffs_ReleaseMountTable();  
+}      
+
+int dfs_uffs_mkfs(const char* device_name)   
+{        
+	return uffs_format(NULL);   
+}      
+
+int dfs_uffs_statfs(struct dfs_filesystem* fs, struct statfs *buf)   
+{
+	int ret = U_SUCC;
+	uffs_MountTable *entry = (uffs_MountTable*)(fs->dev_id->user_data);
+	struct uffs_StorageAttrSt *attr = entry->dev->attr;
+
 	buf->f_bsize  = attr->page_data_size * attr->pages_per_block;
 	buf->f_blocks = attr->total_blocks;
-	buf->f_bfree  = 0;
-
-	return ret;   
-}      
-
-int dfs_uffs_open(struct dfs_fd* fd)   
-{
-	if (fd->flags & DFS_O_DIRECTORY)
-	{	/* directory */
-		uffs_DIR* dirp;
-		int oflag = UO_DIR;
-
-		if (fd->flags & DFS_O_CREAT) oflag |= UO_CREATE;
-		if (fd->flags & DFS_O_RDONLY) oflag |= UO_RDONLY;
-		if (fd->flags & DFS_O_WRONLY) oflag |= UO_WRONLY;
-		
-		if (oflag & UO_CREATE)
-		{	/* create directory right now */
-			uffs_Object* fp = uffs_GetObject();
-			if(fp == NULL) 
-			{
-				uffs_set_error(-UEMFILE);
-				return U_FAIL;
-			}
-	
-			if(uffs_OpenObject(fp, fd->path, oflag) != U_SUCC)
-			{
-				return U_FAIL;
-			}
-			/* release object hander */
-			uffs_PutObject(fp);	
-		}
-
-		/* use directory handler */
-		dirp = uffs_opendir(fd->path);
-		if(dirp == NULL) 
-		{
-			uffs_set_error(-UEMFILE);
-			return U_FAIL;
-		}
-		fd->data = dirp;
-
-		return U_SUCC;
-	}
-	else
-	{/* file */
-		uffs_Object *fp;
-		
-		int mode = UO_RDONLY;
-
-		if (fd->flags & DFS_O_WRONLY) mode |= UO_WRONLY;
-		if ((fd->flags & DFS_O_ACCMODE) & DFS_O_RDWR) mode |= UO_WRONLY;
-		/* Opens the file, if it is existing. If not, a new file is created. */
-		if (fd->flags & DFS_O_CREAT) mode |= UO_CREATE;
-		/* Creates a new file. If the file is existing, it is truncated and overwritten. */
-		if (fd->flags & DFS_O_TRUNC) mode |= UO_TRUNC;
-		/* Creates a new file. The function fails if the file is already existing. */
-		if (fd->flags & DFS_O_EXCL) mode |= UO_EXCL;
-
-		/* get an object hander */
-		fp = uffs_GetObject();
-		if(fp == NULL) 
-		{
-			uffs_set_error(-UEMFILE);
-			return U_FAIL;
-		}
-
-		if(uffs_OpenObject(fp, fd->path, mode) == U_SUCC)
-		{
-			struct uffs_stat stat_buf;
-
-			uffs_stat(fd->path, &stat_buf);
-
-			fd->pos  = fp->pos;
-			fd->size = stat_buf.st_size;
-			fd->data = fp;
-
-			if(fd->flags & DFS_O_APPEND)
-			{
-				fd->pos = uffs_SeekObject(fp, 0, USEEK_END);
-			}
-			return U_SUCC;
-		}
-		else
-		{
-			/* open failed, return */
-			uffs_set_error(-uffs_GetObjectErr(fp));
-			/* release object hander */
-			uffs_PutObject(fp);
-			return U_FAIL;
-		}
-	} 
-}      
-
-
-int dfs_uffs_close(struct dfs_fd* fd)   
-{
-	int ret=U_SUCC;
-
-	if (fd->type == FT_DIRECTORY)
-	{
-		uffs_DIR* dirp;
-		dirp = (uffs_DIR*)(fd->data);
-		RT_ASSERT(dirp != RT_NULL);
-
-		ret = uffs_closedir(dirp);
-	}
-	else if (fd->type == FT_REGULAR)
-	{
-		uffs_Object* fp = (uffs_Object*)(fd->data);
-		RT_ASSERT(fd != RT_NULL);
-
-		ret = uffs_CloseObject(fp);
-		/* release object hander */
-		uffs_PutObject(fp);
-	}
-
-	return ret;   
-}      
-
-int dfs_uffs_ioctl(struct dfs_fd* fd, int cmd, void *args)   
-{
-	return -DFS_STATUS_ENOSYS;   
-}      
-
-int dfs_uffs_read(struct dfs_fd* fd, void* buf, rt_size_t count)   
-{
-	uffs_Object* fp;
-	uffs_DIR* dirp;
-
-	if (fd->type == FT_DIRECTORY)
-	{
-		dirp = (uffs_DIR*)(fd->data);
-		fp = dirp->obj;
-	}
-	else
-	{
-		fp = (uffs_Object*)(fd->data);
-	}
-
-	RT_ASSERT(fd != RT_NULL);
-
-	/* update position */
-	fd->pos  = fp->pos;
-
-	return uffs_ReadObject(fp, buf, count);  
-}      
-
-int dfs_uffs_write(struct dfs_fd* fd, const void* buf, rt_size_t count)   
-{
-	uffs_Object* fp;
-	u32 byte_write;
-	struct uffs_stat stat_buf;
-rt_kprintf("count=%d\n",count);
-	if(fd->type == FT_DIRECTORY)
-	{
-		return -DFS_STATUS_EISDIR;
-	}
-
-	fp = (uffs_Object*)(fd->data);
-	RT_ASSERT(fp != RT_NULL);
-
-	byte_write = uffs_WriteObject(fp, buf, count);
-
-	/* update position and file size */
-	fd->pos  = fp->pos;
-
-	uffs_stat(fp->name, &stat_buf);
-	fd->size = stat_buf.st_size;
-
-	return byte_write;   
-}      
-
-int dfs_uffs_flush(struct dfs_fd* fd)   
-{
-	uffs_Object* fp;
-
-	fp = (uffs_Object*)(fd->data);
-	RT_ASSERT(fp != RT_NULL);
-
-	return uffs_FlushObject(fp); 
-}      
-
-int dfs_uffs_lseek(struct dfs_fd* fd, rt_off_t offset)   
-{
-	uffs_Object* fp;
-
-	fp = (uffs_Object*)(fd->data);
-	RT_ASSERT(fp != RT_NULL);
-
-	return uffs_SeekObject(fp, offset, USEEK_SET);
-}      
-
-int dfs_uffs_getdents(struct dfs_fd* fd, struct dirent* dir, rt_uint32_t count)   
-{
-	uffs_DIR* dirp;
-	struct uffs_dirent *ent;
-	rt_uint32_t index;
-	struct dirent* d;
-
-	if(fd->type != FT_DIRECTORY)
-	{
-		return -DFS_STATUS_EISDIR;
-	}
-
-	dirp = (uffs_DIR*)(fd->data);
-	RT_ASSERT(dirp != RT_NULL);
-
-	/* make integer count */
-	count = (count / sizeof(struct dirent)) * sizeof(struct dirent);
-	if ( count == 0 ) return -DFS_STATUS_EINVAL;
-
-	index = 0;
-	while (1)
-	{
-		d = dir + index;
-
-		ent = uffs_readdir(dirp);
-		if(ent == RT_NULL)break;
-
-
-		d->d_type = DFS_DT_DIR;
-
-		d->d_namlen = ent->d_namelen;
-		d->d_reclen = (rt_uint16_t)sizeof(struct dirent);
-		rt_strncpy(d->d_name, ent->d_name, rt_strlen(ent->d_name) + 1);
-
-		index ++;
-		if ( index * sizeof(struct dirent) >= count )
-			break;
-	}
-	return index * sizeof(struct dirent);
-}      
-
-//Delete a File or Directory
-int dfs_uffs_unlink(struct dfs_filesystem* fs, const char* path)   
-{
-	int ret;
-	int err = 0;
-
-	ret = uffs_DeleteObject(path, &err);
-	uffs_set_error(-err);
-
-	return ret;   
-}      
-
-int dfs_uffs_stat(struct dfs_filesystem* fs, const char* path, struct stat* st)   
-{
-	int ret=U_SUCC;
-	struct uffs_stat stat_buf;
-
-	ret = uffs_stat(path, &stat_buf);
-
-	if (ret == U_SUCC)
-	{
-		rt_uint32_t mode=0;
-		st->st_dev = 0;
-		
-		if(stat_buf.st_mode & US_IFREG)	mode |= DFS_S_IFREG; 
-		if(stat_buf.st_mode & US_IFDIR)	mode |= DFS_S_IFDIR; 
-		if(stat_buf.st_mode & US_IRWXU)	mode |= DFS_S_IRWXU; 
-		if(stat_buf.st_mode & US_IRUSR)	mode |= DFS_S_IRUSR; 
-		if(stat_buf.st_mode & US_IWUSR)	mode |= DFS_S_IWUSR; 
-		if(stat_buf.st_mode & US_IXUSR)	mode |= DFS_S_IXUSR; 
-		if(stat_buf.st_mode & US_IRWXG)	mode |= DFS_S_IRWXG; 
-		if(stat_buf.st_mode & US_IRGRP)	mode |= DFS_S_IRGRP; 
-		if(stat_buf.st_mode & US_IWGRP)	mode |= DFS_S_IWGRP; 
-		if(stat_buf.st_mode & US_IXGRP)	mode |= DFS_S_IXGRP; 
-		if(stat_buf.st_mode & US_IRWXO)	mode |= DFS_S_IRWXO; 
-		if(stat_buf.st_mode & US_IROTH)	mode |= DFS_S_IROTH; 
-		if(stat_buf.st_mode & US_IWOTH)	mode |= DFS_S_IWOTH; 
-		if(stat_buf.st_mode & US_IXOTH)	mode |= DFS_S_IXOTH; 
-
+	buf->f_bfree  = 0;
+
+	return ret;   
+}      
+
+int dfs_uffs_open(struct dfs_fd* fd)   
+{
+	if (fd->flags & DFS_O_DIRECTORY)
+	{	/* directory */
+		uffs_DIR* dirp;
+		int oflag = UO_DIR;
+
+		if (fd->flags & DFS_O_CREAT) oflag |= UO_CREATE;
+		if (fd->flags & DFS_O_RDONLY) oflag |= UO_RDONLY;
+		if (fd->flags & DFS_O_WRONLY) oflag |= UO_WRONLY;
+		
+		if (oflag & UO_CREATE)
+		{	/* create directory right now */
+			uffs_Object* fp = uffs_GetObject();
+			if(fp == NULL) 
+			{
+				uffs_set_error(-UEMFILE);
+				return U_FAIL;
+			}
+	
+			if(uffs_OpenObject(fp, fd->path, oflag) != U_SUCC)
+			{
+				return U_FAIL;
+			}
+			/* release object hander */
+			uffs_PutObject(fp);	
+		}
+
+		/* use directory handler */
+		dirp = uffs_opendir(fd->path);
+		if(dirp == NULL) 
+		{
+			uffs_set_error(-UEMFILE);
+			return U_FAIL;
+		}
+		fd->data = dirp;
+
+		return U_SUCC;
+	}
+	else
+	{/* file */
+		uffs_Object *fp;
+		
+		int mode = UO_RDONLY;
+
+		if (fd->flags & DFS_O_WRONLY) mode |= UO_WRONLY;
+		if ((fd->flags & DFS_O_ACCMODE) & DFS_O_RDWR) mode |= UO_WRONLY;
+		/* Opens the file, if it is existing. If not, a new file is created. */
+		if (fd->flags & DFS_O_CREAT) mode |= UO_CREATE;
+		/* Creates a new file. If the file is existing, it is truncated and overwritten. */
+		if (fd->flags & DFS_O_TRUNC) mode |= UO_TRUNC;
+		/* Creates a new file. The function fails if the file is already existing. */
+		if (fd->flags & DFS_O_EXCL) mode |= UO_EXCL;
+
+		/* get an object hander */
+		fp = uffs_GetObject();
+		if(fp == NULL) 
+		{
+			uffs_set_error(-UEMFILE);
+			return U_FAIL;
+		}
+
+		if(uffs_OpenObject(fp, fd->path, mode) == U_SUCC)
+		{
+			struct uffs_stat stat_buf;
+
+			uffs_stat(fd->path, &stat_buf);
+
+			fd->pos  = fp->pos;
+			fd->size = stat_buf.st_size;
+			fd->data = fp;
+
+			if(fd->flags & DFS_O_APPEND)
+			{
+				fd->pos = uffs_SeekObject(fp, 0, USEEK_END);
+			}
+			return U_SUCC;
+		}
+		else
+		{
+			/* open failed, return */
+			uffs_set_error(-uffs_GetObjectErr(fp));
+			/* release object hander */
+			uffs_PutObject(fp);
+			return U_FAIL;
+		}
+	} 
+}      
+
+
+int dfs_uffs_close(struct dfs_fd* fd)   
+{
+	int ret=U_SUCC;
+
+	if (fd->type == FT_DIRECTORY)
+	{
+		uffs_DIR* dirp;
+		dirp = (uffs_DIR*)(fd->data);
+		RT_ASSERT(dirp != RT_NULL);
+
+		ret = uffs_closedir(dirp);
+	}
+	else if (fd->type == FT_REGULAR)
+	{
+		uffs_Object* fp = (uffs_Object*)(fd->data);
+		RT_ASSERT(fd != RT_NULL);
+
+		ret = uffs_CloseObject(fp);
+		/* release object hander */
+		uffs_PutObject(fp);
+	}
+
+	return ret;   
+}      
+
+int dfs_uffs_ioctl(struct dfs_fd* fd, int cmd, void *args)   
+{
+	return -DFS_STATUS_ENOSYS;   
+}      
+
+int dfs_uffs_read(struct dfs_fd* fd, void* buf, rt_size_t count)   
+{
+	uffs_Object* fp;
+	uffs_DIR* dirp;
+
+	if (fd->type == FT_DIRECTORY)
+	{
+		dirp = (uffs_DIR*)(fd->data);
+		fp = dirp->obj;
+	}
+	else
+	{
+		fp = (uffs_Object*)(fd->data);
+	}
+
+	RT_ASSERT(fd != RT_NULL);
+
+	/* update position */
+	fd->pos  = fp->pos;
+
+	return uffs_ReadObject(fp, buf, count);  
+}      
+
+int dfs_uffs_write(struct dfs_fd* fd, const void* buf, rt_size_t count)   
+{
+	uffs_Object* fp;
+	u32 byte_write;
+	struct uffs_stat stat_buf;
+rt_kprintf("count=%d\n",count);
+	if(fd->type == FT_DIRECTORY)
+	{
+		return -DFS_STATUS_EISDIR;
+	}
+
+	fp = (uffs_Object*)(fd->data);
+	RT_ASSERT(fp != RT_NULL);
+
+	byte_write = uffs_WriteObject(fp, buf, count);
+
+	/* update position and file size */
+	fd->pos  = fp->pos;
+
+	uffs_stat(fp->name, &stat_buf);
+	fd->size = stat_buf.st_size;
+
+	return byte_write;   
+}      
+
+int dfs_uffs_flush(struct dfs_fd* fd)   
+{
+	uffs_Object* fp;
+
+	fp = (uffs_Object*)(fd->data);
+	RT_ASSERT(fp != RT_NULL);
+
+	return uffs_FlushObject(fp); 
+}      
+
+int dfs_uffs_lseek(struct dfs_fd* fd, rt_off_t offset)   
+{
+	uffs_Object* fp;
+
+	fp = (uffs_Object*)(fd->data);
+	RT_ASSERT(fp != RT_NULL);
+
+	return uffs_SeekObject(fp, offset, USEEK_SET);
+}      
+
+int dfs_uffs_getdents(struct dfs_fd* fd, struct dirent* dir, rt_uint32_t count)   
+{
+	uffs_DIR* dirp;
+	struct uffs_dirent *ent;
+	rt_uint32_t index;
+	struct dirent* d;
+
+	if(fd->type != FT_DIRECTORY)
+	{
+		return -DFS_STATUS_EISDIR;
+	}
+
+	dirp = (uffs_DIR*)(fd->data);
+	RT_ASSERT(dirp != RT_NULL);
+
+	/* make integer count */
+	count = (count / sizeof(struct dirent)) * sizeof(struct dirent);
+	if ( count == 0 ) return -DFS_STATUS_EINVAL;
+
+	index = 0;
+	while (1)
+	{
+		d = dir + index;
+
+		ent = uffs_readdir(dirp);
+		if(ent == RT_NULL)break;
+
+
+		d->d_type = DFS_DT_DIR;
+
+		d->d_namlen = ent->d_namelen;
+		d->d_reclen = (rt_uint16_t)sizeof(struct dirent);
+		rt_strncpy(d->d_name, ent->d_name, rt_strlen(ent->d_name) + 1);
+
+		index ++;
+		if ( index * sizeof(struct dirent) >= count )
+			break;
+	}
+	return index * sizeof(struct dirent);
+}      
+
+//Delete a File or Directory
+int dfs_uffs_unlink(struct dfs_filesystem* fs, const char* path)   
+{
+	int ret;
+	int err = 0;
+
+	ret = uffs_DeleteObject(path, &err);
+	uffs_set_error(-err);
+
+	return ret;   
+}      
+
+int dfs_uffs_stat(struct dfs_filesystem* fs, const char* path, struct stat* st)   
+{
+	int ret=U_SUCC;
+	struct uffs_stat stat_buf;
+
+	ret = uffs_stat(path, &stat_buf);
+
+	if (ret == U_SUCC)
+	{
+		rt_uint32_t mode=0;
+		st->st_dev = 0;
+		
+		if(stat_buf.st_mode & US_IFREG)	mode |= DFS_S_IFREG; 
+		if(stat_buf.st_mode & US_IFDIR)	mode |= DFS_S_IFDIR; 
+		if(stat_buf.st_mode & US_IRWXU)	mode |= DFS_S_IRWXU; 
+		if(stat_buf.st_mode & US_IRUSR)	mode |= DFS_S_IRUSR; 
+		if(stat_buf.st_mode & US_IWUSR)	mode |= DFS_S_IWUSR; 
+		if(stat_buf.st_mode & US_IXUSR)	mode |= DFS_S_IXUSR; 
+		if(stat_buf.st_mode & US_IRWXG)	mode |= DFS_S_IRWXG; 
+		if(stat_buf.st_mode & US_IRGRP)	mode |= DFS_S_IRGRP; 
+		if(stat_buf.st_mode & US_IWGRP)	mode |= DFS_S_IWGRP; 
+		if(stat_buf.st_mode & US_IXGRP)	mode |= DFS_S_IXGRP; 
+		if(stat_buf.st_mode & US_IRWXO)	mode |= DFS_S_IRWXO; 
+		if(stat_buf.st_mode & US_IROTH)	mode |= DFS_S_IROTH; 
+		if(stat_buf.st_mode & US_IWOTH)	mode |= DFS_S_IWOTH; 
+		if(stat_buf.st_mode & US_IXOTH)	mode |= DFS_S_IXOTH; 
+
 		st->st_mode = mode;
 		st->st_size = stat_buf.st_size;
 		st->st_mtime= stat_buf.st_mtime;
-		st->st_blksize= stat_buf.st_blksize;
-
-		return U_SUCC;
-	}
-
-	return U_FAIL;
-}      
-
-int dfs_uffs_rename(struct dfs_filesystem* fs, const char* oldpath, const char* newpath)   
-{
-	int ret;
-	int err = 0;
-
-	ret = uffs_RenameObject(oldpath, newpath, &err);
-	uffs_set_error(-err);
-
-	return ret;  
-}      
-
-struct dfs_filesystem_operation _uffs =    
-{           
-	"uffs",           
-	dfs_uffs_mount,           
-	dfs_uffs_unmount,           
-	dfs_uffs_mkfs,           
-	dfs_uffs_statfs,              
-	dfs_uffs_open,           
-	dfs_uffs_close,           
-	dfs_uffs_ioctl,           
-	dfs_uffs_read,           
-	dfs_uffs_write,           
-	dfs_uffs_flush,           
-	dfs_uffs_lseek,           
-	dfs_uffs_getdents,           
-	dfs_uffs_unlink,           
-	dfs_uffs_stat,           
-	dfs_uffs_rename,   
-};      
-
-int dfs_uffs_init(void)   
-{       
-	/* register UFFS file system */       
-	return dfs_register(&_uffs);   
-} 
-
+		st->st_blksize= stat_buf.st_blksize;
+
+		return U_SUCC;
+	}
+
+	return U_FAIL;
+}      
+
+int dfs_uffs_rename(struct dfs_filesystem* fs, const char* oldpath, const char* newpath)   
+{
+	int ret;
+	int err = 0;
+
+	ret = uffs_RenameObject(oldpath, newpath, &err);
+	uffs_set_error(-err);
+
+	return ret;  
+}      
+
+struct dfs_filesystem_operation _uffs =    
+{           
+	"uffs",
+	DFS_FS_FLAG_DEFAULT,	
+	dfs_uffs_mount,           
+	dfs_uffs_unmount,           
+	dfs_uffs_mkfs,           
+	dfs_uffs_statfs,              
+	dfs_uffs_open,           
+	dfs_uffs_close,           
+	dfs_uffs_ioctl,           
+	dfs_uffs_read,           
+	dfs_uffs_write,           
+	dfs_uffs_flush,           
+	dfs_uffs_lseek,           
+	dfs_uffs_getdents,           
+	dfs_uffs_unlink,           
+	dfs_uffs_stat,           
+	dfs_uffs_rename,   
+};      
+
+int dfs_uffs_init(void)   
+{       
+	/* register UFFS file system */       
+	return dfs_register(&_uffs);   
+} 
+
diff --git a/components/dfs/include/dfs_fs.h b/components/dfs/include/dfs_fs.h
index 2108d07c82..90a5b50d69 100644
--- a/components/dfs/include/dfs_fs.h
+++ b/components/dfs/include/dfs_fs.h
@@ -17,6 +17,9 @@
 
 #include <dfs_def.h>
 
+#define DFS_FS_FLAG_DEFAULT		0x00	/* default flag */
+#define DFS_FS_FLAG_FULLPATH	0x01	/* set full path to underlaying file system */
+
 /* Pre-declaration */
 struct dfs_filesystem;
 struct dfs_fd;
@@ -25,6 +28,7 @@ struct dfs_fd;
 struct dfs_filesystem_operation
 {
 	char *name;
+	rt_uint32_t flags;		/* flags for file system operations */
 
 	/* mount and unmount file system */
 	int (*mount)	(struct dfs_filesystem *fs, unsigned long rwflag, const void *data);
diff --git a/components/dfs/src/dfs_file.c b/components/dfs/src/dfs_file.c
index 25de66af11..b9f050b602 100644
--- a/components/dfs/src/dfs_file.c
+++ b/components/dfs/src/dfs_file.c
@@ -66,13 +66,20 @@ int dfs_file_open(struct dfs_fd *fd, const char *path, int flags)
 	fd->size = 0;
 	fd->pos = 0;
 
-	if (dfs_subdir(fs->path, fullpath) == RT_NULL)
-		fd->path = rt_strdup("/");
+	if (!(fs->ops->flags & DFS_FS_FLAG_FULLPATH))
+	{
+		if (dfs_subdir(fs->path, fullpath) == RT_NULL)
+			fd->path = rt_strdup("/");
+		else
+			fd->path = rt_strdup(dfs_subdir(fs->path, fullpath));
+		rt_free(fullpath);
+		dfs_log(DFS_DEBUG_INFO, ("Actual file path: %s\n", fd->path));
+	}
 	else
-		fd->path = rt_strdup(dfs_subdir(fs->path, fullpath));
-	rt_free(fullpath);
-	dfs_log(DFS_DEBUG_INFO, ("Actual file path: %s\n", fd->path));
-
+	{
+		fd->path = fullpath;	
+	}
+	
 	/* specific file system open routine */
 	if (fs->ops->open == RT_NULL)
 	{
@@ -241,10 +248,15 @@ int dfs_file_unlink(const char *path)
 
 	if (fs->ops->unlink != RT_NULL)
 	{
-		if (dfs_subdir(fs->path, fullpath) == RT_NULL)
-			result = fs->ops->unlink(fs, "/");
+		if (!(fs->ops->flags & DFS_FS_FLAG_FULLPATH))
+		{
+			if (dfs_subdir(fs->path, fullpath) == RT_NULL)
+				result = fs->ops->unlink(fs, "/");
+			else
+				result = fs->ops->unlink(fs, dfs_subdir(fs->path, fullpath));
+		}
 		else
-			result = fs->ops->unlink(fs, dfs_subdir(fs->path, fullpath));
+			result = fs->ops->unlink(fs, fullpath);				
 	}
 	else result = -DFS_STATUS_ENOSYS;
 
@@ -380,7 +392,11 @@ int dfs_file_stat(const char *path, struct stat *buf)
 		}
 
 		/* get the real file path and get file stat */
-		result = fs->ops->stat(fs, dfs_subdir(fs->path, fullpath), buf);
+		if (fs->ops->flags & DFS_FS_FLAG_FULLPATH)
+			result = fs->ops->stat(fs, fullpath, buf);	 
+		else
+			result = fs->ops->stat(fs, dfs_subdir(fs->path, fullpath), buf);
+			
 	}
 
 	rt_free(fullpath);