s390/hypfs: add interface for diagnose 0x304

To provide access to the set-partition-resource-parameter interface
to user space add a new attribute to hypfs/debugfs:
 * s390_hypsfs/diag_304
The data for the query-partition-resource-parameters command can
be access by a read on the attribute. All other diagnose 0x304
requests need to be submitted via ioctl with CAP_SYS_ADMIN rights.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/arch/s390/hypfs/hypfs_dbfs.c b/arch/s390/hypfs/hypfs_dbfs.c
index 17ab8b7b53cc..2badf2bf9cd7 100644
--- a/arch/s390/hypfs/hypfs_dbfs.c
+++ b/arch/s390/hypfs/hypfs_dbfs.c
@@ -81,9 +81,25 @@ static ssize_t dbfs_read(struct file *file, char __user *buf,
 	return rc;
 }
 
+static long dbfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	struct hypfs_dbfs_file *df;
+	long rc;
+
+	df = file->f_path.dentry->d_inode->i_private;
+	mutex_lock(&df->lock);
+	if (df->unlocked_ioctl)
+		rc = df->unlocked_ioctl(file, cmd, arg);
+	else
+		rc = -ENOTTY;
+	mutex_unlock(&df->lock);
+	return rc;
+}
+
 static const struct file_operations dbfs_ops = {
 	.read		= dbfs_read,
 	.llseek		= no_llseek,
+	.unlocked_ioctl = dbfs_ioctl,
 };
 
 int hypfs_dbfs_create_file(struct hypfs_dbfs_file *df)