s390/hypfs: Eliminate hypfs interval

Currently the binary hypfs interfaces provides new data only once within
an interval time of one second. This patch removes this restriction and
now new data is returned immediately on every read on a hypfs binary file.

This is done in order to allow more consistent snapshots for programs
that read multiple hypfs binary files.
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/hypfs/hypfs.h

@@ -53,7 +53,6 @@ struct hypfs_dbfs_data {
 	void			*buf_free_ptr;
 	size_t			size;
 	struct hypfs_dbfs_file	*dbfs_file;
-	struct kref		kref;
 };
 
 struct hypfs_dbfs_file {
@@ -65,8 +64,6 @@ struct hypfs_dbfs_file {
 					   unsigned long);
 
 	/* Private data for hypfs_dbfs.c */
-	struct hypfs_dbfs_data	*data;
-	struct delayed_work	data_free_work;
 	struct mutex		lock;
 	struct dentry		*dentry;
 };

arch/s390/hypfs/hypfs_dbfs.c

@@ -17,33 +17,16 @@ static struct hypfs_dbfs_data *hypfs_dbfs_data_alloc(struct hypfs_dbfs_file *f)
 	data = kmalloc(sizeof(*data), GFP_KERNEL);
 	if (!data)
 		return NULL;
-	kref_init(&data->kref);
 	data->dbfs_file = f;
 	return data;
 }
 
-static void hypfs_dbfs_data_free(struct kref *kref)
+static void hypfs_dbfs_data_free(struct hypfs_dbfs_data *data)
 {
-	struct hypfs_dbfs_data *data;
-
-	data = container_of(kref, struct hypfs_dbfs_data, kref);
 	data->dbfs_file->data_free(data->buf_free_ptr);
 	kfree(data);
 }
 
-static void data_free_delayed(struct work_struct *work)
-{
-	struct hypfs_dbfs_data *data;
-	struct hypfs_dbfs_file *df;
-
-	df = container_of(work, struct hypfs_dbfs_file, data_free_work.work);
-	mutex_lock(&df->lock);
-	data = df->data;
-	df->data = NULL;
-	mutex_unlock(&df->lock);
-	kref_put(&data->kref, hypfs_dbfs_data_free);
-}
-
 static ssize_t dbfs_read(struct file *file, char __user *buf,
 			 size_t size, loff_t *ppos)
 {
@@ -56,28 +39,21 @@ static ssize_t dbfs_read(struct file *file, char __user *buf,
 
 	df = file_inode(file)->i_private;
 	mutex_lock(&df->lock);
-	if (!df->data) {
-		data = hypfs_dbfs_data_alloc(df);
-		if (!data) {
-			mutex_unlock(&df->lock);
-			return -ENOMEM;
-		}
-		rc = df->data_create(&data->buf, &data->buf_free_ptr,
-				     &data->size);
-		if (rc) {
-			mutex_unlock(&df->lock);
-			kfree(data);
-			return rc;
-		}
-		df->data = data;
-		schedule_delayed_work(&df->data_free_work, HZ);
+	data = hypfs_dbfs_data_alloc(df);
+	if (!data) {
+		mutex_unlock(&df->lock);
+		return -ENOMEM;
+	}
+	rc = df->data_create(&data->buf, &data->buf_free_ptr, &data->size);
+	if (rc) {
+		mutex_unlock(&df->lock);
+		kfree(data);
+		return rc;
 	}
-	data = df->data;
-	kref_get(&data->kref);
 	mutex_unlock(&df->lock);
 
 	rc = simple_read_from_buffer(buf, size, ppos, data->buf, data->size);
-	kref_put(&data->kref, hypfs_dbfs_data_free);
+	hypfs_dbfs_data_free(data);
 	return rc;
 }
 
@@ -108,7 +84,6 @@ int hypfs_dbfs_create_file(struct hypfs_dbfs_file *df)
 	if (IS_ERR(df->dentry))
 		return PTR_ERR(df->dentry);
 	mutex_init(&df->lock);
-	INIT_DELAYED_WORK(&df->data_free_work, data_free_delayed);
 	return 0;
 }