fs/adfs: dir: add more efficient iterate() per-format method

Rather than using setpos + getnext to iterate through the directory
entries, pass iterate() down to the dir format code to populate the
dirents.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/adfs/adfs.h

@@ -120,6 +120,7 @@ struct object_info {
 struct adfs_dir_ops {
 	int	(*read)(struct super_block *sb, unsigned int indaddr,
 			unsigned int size, struct adfs_dir *dir);
+	int	(*iterate)(struct adfs_dir *dir, struct dir_context *ctx);
 	int	(*setpos)(struct adfs_dir *dir, unsigned int fpos);
 	int	(*getnext)(struct adfs_dir *dir, struct object_info *obj);
 	int	(*update)(struct adfs_dir *dir, struct object_info *obj);

fs/adfs/dir.c

@@ -240,12 +240,8 @@ static int adfs_iterate(struct file *file, struct dir_context *ctx)
 	struct inode *inode = file_inode(file);
 	struct super_block *sb = inode->i_sb;
 	const struct adfs_dir_ops *ops = ADFS_SB(sb)->s_dir;
-	struct object_info obj;
 	struct adfs_dir dir;
-	int ret = 0;
-
-	if (ctx->pos >> 32)
-		return 0;
+	int ret;
 
 	down_read(&adfs_dir_rwsem);
 	ret = adfs_dir_read_inode(sb, inode, &dir);
@@ -263,15 +259,7 @@ static int adfs_iterate(struct file *file, struct dir_context *ctx)
 		ctx->pos = 2;
 	}
 
-	ret = ops->setpos(&dir, ctx->pos - 2);
-	if (ret)
-		goto unlock_relse;
-	while (ops->getnext(&dir, &obj) == 0) {
-		if (!dir_emit(ctx, obj.name, obj.name_len,
-			      obj.indaddr, DT_UNKNOWN))
-			break;
-		ctx->pos++;
-	}
+	ret = ops->iterate(&dir, ctx);
 
 unlock_relse:
 	up_read(&adfs_dir_rwsem);

fs/adfs/dir_f.c

@@ -302,6 +302,23 @@ adfs_f_getnext(struct adfs_dir *dir, struct object_info *obj)
 	return ret;
 }
 
+static int adfs_f_iterate(struct adfs_dir *dir, struct dir_context *ctx)
+{
+	struct object_info obj;
+	int pos = 5 + (ctx->pos - 2) * 26;
+
+	while (ctx->pos < 2 + ADFS_NUM_DIR_ENTRIES) {
+		if (__adfs_dir_get(dir, pos, &obj))
+			break;
+		if (!dir_emit(ctx, obj.name, obj.name_len,
+			      obj.indaddr, DT_UNKNOWN))
+			break;
+		pos += 26;
+		ctx->pos++;
+	}
+	return 0;
+}
+
 static int
 adfs_f_update(struct adfs_dir *dir, struct object_info *obj)
 {
@@ -359,6 +376,7 @@ adfs_f_update(struct adfs_dir *dir, struct object_info *obj)
 
 const struct adfs_dir_ops adfs_f_dir_ops = {
 	.read		= adfs_f_read,
+	.iterate	= adfs_f_iterate,
 	.setpos		= adfs_f_setpos,
 	.getnext	= adfs_f_getnext,
 	.update		= adfs_f_update,

fs/adfs/dir_fplus.c

@@ -118,8 +118,29 @@ adfs_fplus_getnext(struct adfs_dir *dir, struct object_info *obj)
 	return 0;
 }
 
+static int adfs_fplus_iterate(struct adfs_dir *dir, struct dir_context *ctx)
+{
+	struct object_info obj;
+
+	if ((ctx->pos - 2) >> 32)
+		return 0;
+
+	if (adfs_fplus_setpos(dir, ctx->pos - 2))
+		return 0;
+
+	while (!adfs_fplus_getnext(dir, &obj)) {
+		if (!dir_emit(ctx, obj.name, obj.name_len,
+			      obj.indaddr, DT_UNKNOWN))
+			break;
+		ctx->pos++;
+	}
+
+	return 0;
+}
+
 const struct adfs_dir_ops adfs_fplus_dir_ops = {
 	.read		= adfs_fplus_read,
+	.iterate	= adfs_fplus_iterate,
 	.setpos		= adfs_fplus_setpos,
 	.getnext	= adfs_fplus_getnext,
 };