[readdir] convert sysfs

get rid of the kludges in sysfs_readdir()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/sysfs/dir.c

@@ -998,68 +998,38 @@ static struct sysfs_dirent *sysfs_dir_next_pos(const void *ns,
 	return pos;
 }
 
-static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
+static int sysfs_readdir(struct file *file, struct dir_context *ctx)
 {
-	struct dentry *dentry = filp->f_path.dentry;
+	struct dentry *dentry = file->f_path.dentry;
 	struct sysfs_dirent * parent_sd = dentry->d_fsdata;
-	struct sysfs_dirent *pos = filp->private_data;
+	struct sysfs_dirent *pos = file->private_data;
 	enum kobj_ns_type type;
 	const void *ns;
-	ino_t ino;
-	loff_t off;
 
 	type = sysfs_ns_type(parent_sd);
 	ns = sysfs_info(dentry->d_sb)->ns[type];
 
-	if (filp->f_pos == 0) {
-		ino = parent_sd->s_ino;
-		if (filldir(dirent, ".", 1, filp->f_pos, ino, DT_DIR) == 0)
-			filp->f_pos++;
-		else
-			return 0;
-	}
-	if (filp->f_pos == 1) {
-		if (parent_sd->s_parent)
-			ino = parent_sd->s_parent->s_ino;
-		else
-			ino = parent_sd->s_ino;
-		if (filldir(dirent, "..", 2, filp->f_pos, ino, DT_DIR) == 0)
-			filp->f_pos++;
-		else
-			return 0;
-	}
+	if (!dir_emit_dots(file, ctx))
+		return 0;
 	mutex_lock(&sysfs_mutex);
-	off = filp->f_pos;
-	for (pos = sysfs_dir_pos(ns, parent_sd, filp->f_pos, pos);
+	for (pos = sysfs_dir_pos(ns, parent_sd, ctx->pos, pos);
 	     pos;
-	     pos = sysfs_dir_next_pos(ns, parent_sd, filp->f_pos, pos)) {
-		const char * name;
-		unsigned int type;
-		int len, ret;
-
-		name = pos->s_name;
-		len = strlen(name);
-		ino = pos->s_ino;
-		type = dt_type(pos);
-		off = filp->f_pos = pos->s_hash;
-		filp->private_data = sysfs_get(pos);
+	     pos = sysfs_dir_next_pos(ns, parent_sd, ctx->pos, pos)) {
+		const char *name = pos->s_name;
+		unsigned int type = dt_type(pos);
+		int len = strlen(name);
+		ino_t ino = pos->s_ino;
+		ctx->pos = pos->s_hash;
+		file->private_data = sysfs_get(pos);
 
 		mutex_unlock(&sysfs_mutex);
-		ret = filldir(dirent, name, len, off, ino, type);
+		if (!dir_emit(ctx, name, len, ino, type))
+			return 0;
 		mutex_lock(&sysfs_mutex);
-		if (ret < 0)
-			break;
 	}
 	mutex_unlock(&sysfs_mutex);
-
-	/* don't reference last entry if its refcount is dropped */
-	if (!pos) {
-		filp->private_data = NULL;
-
-		/* EOF and not changed as 0 or 1 in read/write path */
-		if (off == filp->f_pos && off > 1)
-			filp->f_pos = INT_MAX;
-	}
+	file->private_data = NULL;
+	ctx->pos = INT_MAX;
 	return 0;
 }
 
@@ -1077,7 +1047,7 @@ static loff_t sysfs_dir_llseek(struct file *file, loff_t offset, int whence)
 
 const struct file_operations sysfs_dir_operations = {
 	.read		= generic_read_dir,
-	.readdir	= sysfs_readdir,
+	.iterate	= sysfs_readdir,
 	.release	= sysfs_dir_release,
 	.llseek		= sysfs_dir_llseek,
 };