fat: Cleanup FAT attribute stuff

This adds three helpers:

fat_make_attrs() - makes FAT attributes from inode.
fat_make_mode()  - makes mode_t from FAT attributes.
fat_save_attrs() - saves FAT attributes to inode.

Then this replaces: MSDOS_MKMODE() by fat_make_mode(), fat_attr() by
fat_make_attrs(), ->i_attrs = attr & ATTR_UNUSED by fat_save_attrs().
And for root inode, those is used with ATTR_DIR instead of bogus
ATTR_NONE.

Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/fat/file.c b/fs/fat/file.c
index b21973f..f5a7e90 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -27,13 +27,7 @@
 	switch (cmd) {
 	case FAT_IOCTL_GET_ATTRIBUTES:
 	{
-		u32 attr;
-
-		if (inode->i_ino == MSDOS_ROOT_INO)
-			attr = ATTR_DIR;
-		else
-			attr = fat_attr(inode);
-
+		u32 attr = fat_make_attrs(inode);
 		return put_user(attr, user_attr);
 	}
 	case FAT_IOCTL_SET_ATTRIBUTES:
@@ -62,20 +56,16 @@
 		/* Merge in ATTR_VOLUME and ATTR_DIR */
 		attr |= (MSDOS_I(inode)->i_attrs & ATTR_VOLUME) |
 			(is_dir ? ATTR_DIR : 0);
-		oldattr = fat_attr(inode);
+		oldattr = fat_make_attrs(inode);
 
 		/* Equivalent to a chmod() */
 		ia.ia_valid = ATTR_MODE | ATTR_CTIME;
 		ia.ia_ctime = current_fs_time(inode->i_sb);
-		if (is_dir) {
-			ia.ia_mode = MSDOS_MKMODE(attr,
-				S_IRWXUGO & ~sbi->options.fs_dmask)
-				| S_IFDIR;
-		} else {
-			ia.ia_mode = MSDOS_MKMODE(attr,
-				(S_IRUGO | S_IWUGO | (inode->i_mode & S_IXUGO))
-				& ~sbi->options.fs_fmask)
-				| S_IFREG;
+		if (is_dir)
+			ia.ia_mode = fat_make_mode(sbi, attr, S_IRWXUGO);
+		else {
+			ia.ia_mode = fat_make_mode(sbi, attr,
+				S_IRUGO | S_IWUGO | (inode->i_mode & S_IXUGO));
 		}
 
 		/* The root directory has no attributes */
@@ -115,7 +105,7 @@
 				inode->i_flags &= S_IMMUTABLE;
 		}
 
-		MSDOS_I(inode)->i_attrs = attr & ATTR_UNUSED;
+		fat_save_attrs(inode, attr);
 		mark_inode_dirty(inode);
 up:
 		mnt_drop_write(filp->f_path.mnt);
@@ -274,7 +264,7 @@
 
 	/*
 	 * Note, the basic check is already done by a caller of
-	 * (attr->ia_mode & ~MSDOS_VALID_MODE)
+	 * (attr->ia_mode & ~FAT_VALID_MODE)
 	 */
 
 	if (S_ISREG(inode->i_mode))
@@ -314,6 +304,8 @@
 }
 
 #define TIMES_SET_FLAGS	(ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)
+/* valid file mode bits */
+#define FAT_VALID_MODE	(S_IFREG | S_IFDIR | S_IRWXUGO)
 
 int fat_setattr(struct dentry *dentry, struct iattr *attr)
 {
@@ -356,7 +348,7 @@
 	    ((attr->ia_valid & ATTR_GID) &&
 	     (attr->ia_gid != sbi->options.fs_gid)) ||
 	    ((attr->ia_valid & ATTR_MODE) &&
-	     (attr->ia_mode & ~MSDOS_VALID_MODE)))
+	     (attr->ia_mode & ~FAT_VALID_MODE)))
 		error = -EPERM;
 
 	if (error) {