diff --git a/filesystem/dfs/filesystems/efsl/src/base/efs.c b/filesystem/dfs/filesystems/efsl/src/base/efs.c
index 2ac98abb55..86627f322b 100644
--- a/filesystem/dfs/filesystems/efsl/src/base/efs.c
+++ b/filesystem/dfs/filesystems/efsl/src/base/efs.c
@@ -12,11 +12,14 @@
  * 2008-08-16     Yi.Qiu		The first version.
  */
  
+ #include <string.h>
+
 #include "efs.h"
+#include "dfs_cache.h"
+
 #include "ls.h"
 #include "ui.h"
 #include "fat.h"
-#include <string.h>
 
 #define EFS_MAX		2
 
@@ -24,7 +27,7 @@ struct dfs_filesystem_operation efs;
 
 /**
  * This function will initialize efsl to DFS interface.
- * 
+ * 
  * @return 0 on succesful
  */
 int efsl_init()
@@ -65,8 +68,8 @@ int efs_mount(struct dfs_filesystem* fs)
 	efsl_fs* efsfs;
 	int result;
 
-	/* allocate an EFS filesystem entry */
-	efsfs = (efsl_fs*) rt_malloc (sizeof(efsl_fs));
+	/* allocate an EFS filesystem entry */
+	efsfs = (efsl_fs*) rt_malloc (sizeof(efsl_fs));
 
 	/* init efs filesystem struct */
 	efsfs->partition.ioman = rt_malloc(sizeof(IOManager));
@@ -74,7 +77,7 @@ int efs_mount(struct dfs_filesystem* fs)
 
 	part_initPartition(&efsfs->partition);
 	ioman_init(efsfs->partition.ioman);
-	result = fs_initFs(&efsfs->filesystem ,&efsfs->partition);
+	result = fs_initFs(&efsfs->filesystem ,&efsfs->partition);
 
 	/* set to DFS filesystem user data */
 	fs->data = efsfs;
@@ -96,7 +99,7 @@ int efs_unmount(struct dfs_filesystem* fs)
 	if ( efsfs == RT_NULL ) return -DFS_STATUS_EINVAL;
 
 	fs_flushFs(&efsfs->filesystem);
-	rt_free(efsfs->partition.ioman);
+	rt_free(efsfs->partition.ioman);
 	rt_free(efsfs);
 
 	fs->data = RT_NULL;
@@ -202,19 +205,19 @@ int efs_close(struct dfs_fd* file)
 {
 	int result = 0;
 	
-	if (!file || !(file->flags & DFS_F_OPEN)) return -DFS_STATUS_EBADF;
+	if (!file || !(file->flags & DFS_F_OPEN)) return -DFS_STATUS_EBADF;
 	
 	if(!(file->flags & DFS_F_DIRECTORY)) 
 		result = file_fclose((File *)file->data);
-	else
-	{
+	else
+	{
 		dfs_log(DFS_DEBUG_INFO, ("close a directory, %s", file->path));
-	}
+	}
 
 	dfs_log(DFS_DEBUG_INFO, ("close a file, %s", file->path));
 
 	/* free directory or file */
-	rt_free(file->data);
+	rt_free(file->data);
 	file->data = RT_NULL;
 
 	return result;
@@ -242,8 +245,8 @@ int efs_read(struct dfs_fd* file, void* buf, rt_size_t len)
 	File* efsfile = file->data;
 	int result = 0;
 
-	/* parameter check */
-	RT_ASSERT(efsfile != RT_NULL);
+	/* parameter check */
+	RT_ASSERT(efsfile != RT_NULL);
 	
 	result = file_read(efsfile, len, buf);
 	file->pos = efsfile->FilePtr;
@@ -264,8 +267,8 @@ int efs_write(struct dfs_fd* file, const void* buf, rt_size_t len)
 	File* efsfile = file->data;
 	int result = 0;
 
-	/* parameter check */
-	RT_ASSERT(efsfile != RT_NULL);
+	/* parameter check */
+	RT_ASSERT(efsfile != RT_NULL);
 	
 	result = file_write(efsfile, len, (euint8 *)buf);
 	file->pos = efsfile->FilePtr;
@@ -286,9 +289,9 @@ int efs_lseek(struct dfs_fd* file, rt_off_t offset)
 {
 	int result = 0;
 	DirList* efsdir;
-	efsl_fs* efsfs = (efsl_fs *)file->fs->data;
+	efsl_fs* efsfs = (efsl_fs *)file->fs->data;
 
-	/* parameter check */
+	/* parameter check */
 	RT_ASSERT(efsfs   != RT_NULL);
 
 	/* seek directory */
@@ -365,7 +368,7 @@ int efs_getdents(struct dfs_fd* file, struct dfs_dirent* dirp, rt_uint32_t count
 		result ++;
 
 		/* is it enough? */
-		if ( result * sizeof(struct dfs_dirent) >= count )
+		if ( result * sizeof(struct dfs_dirent) >= count )
 			break;
 	}
 
@@ -380,13 +383,13 @@ int efs_getdents(struct dfs_fd* file, struct dfs_dirent* dirp, rt_uint32_t count
  */
 int efs_unlink(struct dfs_filesystem* fs, const char* path)
 {
-	efsl_fs* efsfs;
+	efsl_fs* efsfs;
 
-	RT_ASSERT(fs   != RT_NULL);
-	efsfs = (efsl_fs *)fs->data;
+	RT_ASSERT(fs   != RT_NULL);
+	efsfs = (efsl_fs *)fs->data;
 
-	RT_ASSERT(path  != RT_NULL);
-	RT_ASSERT(efsfs != RT_NULL);
+	RT_ASSERT(path  != RT_NULL);
+	RT_ASSERT(efsfs != RT_NULL);
 	
 	return un_link(&efsfs->filesystem, (euint8 *)path);
 }
@@ -403,7 +406,7 @@ int efs_stat(struct dfs_filesystem* fs, const char *path, struct dfs_stat *st)
 	FileLocation loc;
 	efsl_fs* efsfs = (efsl_fs*)(fs->data);
 
-	/* parameter check */
+	/* parameter check */
 	RT_ASSERT(efsfs != RT_NULL);
 	
 	/* file does not exist */
@@ -446,7 +449,7 @@ int efs_rename(struct dfs_filesystem* fs, const char* oldpath, const char* newpa
 	eint8 fatfilename[11];
 	
 	efsfs = (efsl_fs*) fs->data ;
-	RT_ASSERT(efsfs != RT_NULL);
+	RT_ASSERT(efsfs != RT_NULL);
 
 	dir_getFatFileName((eint8 *)newpath, &fatfilename[0]);	
 	
diff --git a/filesystem/dfs/filesystems/efsl/src/fs/vfat/dir.c b/filesystem/dfs/filesystems/efsl/src/fs/vfat/dir.c
index 4cf13ca4a0..1d6da08d66 100644
--- a/filesystem/dfs/filesystems/efsl/src/fs/vfat/dir.c
+++ b/filesystem/dfs/filesystems/efsl/src/fs/vfat/dir.c
@@ -217,13 +217,8 @@ euint32  dir_findinBuf(euint8 *buf, eint8 *fatname, FileLocation *loc, euint8 mo
 	switch(mode){
 		case DIRFIND_FILE:
 			return(dir_findFileinBuf(buf,fatname,loc));
-			break;
 		case DIRFIND_FREE:
 			return(dir_findFreeEntryinBuf(buf,loc));
-			break;
-		default:
-			return(0);
-			break;
 	}
 	return(0);
 }
@@ -274,10 +269,9 @@ euint32 dir_findinDir(FileSystem *fs, eint8* fatname,euint32 firstcluster, FileL
 		return(dir_findinRootArea(fs,fatname,loc,mode));	
 	}
 	
-	while(!fat_LogicToDiscCluster(fs,&Cache,c++)){
-		if((cluster=dir_findinCluster(fs,Cache.DiscCluster,fatname,loc,mode))){
-			return(cluster);
-		}
+	while(!fat_LogicToDiscCluster(fs,&Cache,c++)){
+		cluster=dir_findinCluster(fs,Cache.DiscCluster,fatname,loc,mode);
+		if(cluster) return(cluster);
 	}
 	return(0);
 }
@@ -296,8 +290,9 @@ euint32 dir_findinRootArea(FileSystem *fs,eint8* fatname, FileLocation *loc, eui
 	if((fs->type != FAT12) && (fs->type != FAT16))return(0);
 	
 	for(c=fs->FirstSectorRootDir;c<(fs->FirstSectorRootDir+fs->volumeId.RootEntryCount/32);c++){
-		buf = part_getSect(fs->part,c,IOM_MODE_READONLY);
-		if((fclus=dir_findinBuf(buf,fatname,loc,mode))){
+		buf = part_getSect(fs->part,c,IOM_MODE_READONLY);
+		fclus=dir_findinBuf(buf,fatname,loc,mode);
+		if(fclus){
 			if(loc)loc->Sector=c;
 			part_relSect(fs->part,buf);
 			return(fclus);
@@ -322,10 +317,13 @@ esint8 dir_getFatFileName(eint8* filename, eint8* fatfilename)
 	next = filename;
 	
 	if(*filename=='/')next++;
-	
-	while((next=file_normalToFatName(next,ffnamec))){
+	
+	next=file_normalToFatName(next,ffnamec);
+	while(next){
 		memCpy(ffnamec,fatfilename,11);	
-		nn++;
+		nn++;
+		
+		next=file_normalToFatName(next,ffnamec);
 	}
 	if(nn)return(1);
 	return(0);
diff --git a/filesystem/dfs/filesystems/efsl/src/fs/vfat/fat.c b/filesystem/dfs/filesystems/efsl/src/fs/vfat/fat.c
index b9f856cf10..4f9a3f4752 100644
--- a/filesystem/dfs/filesystems/efsl/src/fs/vfat/fat.c
+++ b/filesystem/dfs/filesystems/efsl/src/fs/vfat/fat.c
@@ -51,26 +51,21 @@ euint32 fat_getSectorAddressFatEntry(FileSystem *fs,euint32 cluster_addr)
 			res=(cluster_addr*3/1024);
 			if(res>=fs->FatSectorCount){
 				return(0);
-			}else{
-				return(base+res);
-			}
-			break;
+			}			
+			return(base+res);
+
 		case FAT16:
 			res=cluster_addr/256;
 			if(res>=fs->FatSectorCount){
 				return(0);
-			}else{
-				return(base+res);
 			}
-			break;
+			return(base+res);
 		case FAT32:
 			res=cluster_addr/128;
 			if(res>=fs->FatSectorCount){
 				return(0);
-			}else{
-				return(base+res);
-			}
-			break; 
+			}
+			return(base+res);
 	}
 	return(0);
 }
@@ -241,13 +236,10 @@ euint32 fat_giveEocMarker(FileSystem *fs)
 	{
 		case FAT12:
 			return(0xFFF);
-			break;
 		case FAT16:
 			return(0xFFFF);
-			break;
 		case FAT32:
 			return(0x0FFFFFFF);
-			break;
 	}
 	return(0);
 }
diff --git a/filesystem/dfs/include/dfs_def.h b/filesystem/dfs/include/dfs_def.h
index 27b05e20e0..d04cbda5db 100644
--- a/filesystem/dfs/include/dfs_def.h
+++ b/filesystem/dfs/include/dfs_def.h
@@ -30,6 +30,7 @@
 #endif
 
 /* Device error codes */
+#define DFS_STATUS_OK			0		/* no error */
 #define DFS_STATUS_ENOENT		2		/* No such file or directory */
 #define DFS_STATUS_EIO		 	5		/* I/O error */
 #define DFS_STATUS_ENXIO		6		/* No such device or address */
diff --git a/filesystem/dfs/src/dfs_posix.c b/filesystem/dfs/src/dfs_posix.c
index 6ea66a0e76..fb4a0ee2ed 100644
--- a/filesystem/dfs/src/dfs_posix.c
+++ b/filesystem/dfs/src/dfs_posix.c
@@ -513,7 +513,7 @@ int chdir(const char *path)
 {
 	char* fullpath, full_path[DFS_PATH_MAX + 1];
 	
-	if(path == RT_NULL || strlen(path) > DFS_PATH_MAX)
+	if(path == RT_NULL || rt_strlen(path) > DFS_PATH_MAX)
 		return -1;
 
 	fullpath = (char*)path;
diff --git a/filesystem/dfs/src/dfs_util.c b/filesystem/dfs/src/dfs_util.c
index 455c9f1f9d..af7bab3bf6 100644
--- a/filesystem/dfs/src/dfs_util.c
+++ b/filesystem/dfs/src/dfs_util.c
@@ -262,8 +262,6 @@ char *strrchr(const char *t, int c)
 		if ((*t == ch)) l=t;
 		if ((!*t)) return (char*)l; ++t;
 	}
-
-	return (char*)l;
 }
 #endif