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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/arch/s390/hypfs/hypfs_dbfs.c
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// SPDX-License-Identifier: GPL-2.0

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/*

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 * Hypervisor filesystem for Linux on s390 - debugfs interface

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 *

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 * Copyright IBM Corp. 2010

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 * Author(s): Michael Holzheu <[email protected]>

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 */

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#include <linux/security.h>

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#include <linux/slab.h>

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#include "hypfs.h"

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static struct dentry *dbfs_dir;

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static struct hypfs_dbfs_data *hypfs_dbfs_data_alloc(struct hypfs_dbfs_file *f)

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{

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	struct hypfs_dbfs_data *data;

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	data = kmalloc(sizeof(*data), GFP_KERNEL);

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	if (!data)

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		return NULL;

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	data->dbfs_file = f;

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	return data;

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}

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static void hypfs_dbfs_data_free(struct hypfs_dbfs_data *data)

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{

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	data->dbfs_file->data_free(data->buf_free_ptr);

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	kfree(data);

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}

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static ssize_t dbfs_read(struct file *file, char __user *buf,

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			 size_t size, loff_t *ppos)

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{

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	struct hypfs_dbfs_data *data;

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	struct hypfs_dbfs_file *df;

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	ssize_t rc;

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	if (*ppos != 0)

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		return 0;

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	df = file_inode(file)->i_private;

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	if (mutex_lock_interruptible(&df->lock))

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		return -ERESTARTSYS;

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	data = hypfs_dbfs_data_alloc(df);

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	if (!data) {

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		mutex_unlock(&df->lock);

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		return -ENOMEM;

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	}

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	rc = df->data_create(&data->buf, &data->buf_free_ptr, &data->size);

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	if (rc) {

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		mutex_unlock(&df->lock);

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		kfree(data);

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		return rc;

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	}

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	mutex_unlock(&df->lock);

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	rc = simple_read_from_buffer(buf, size, ppos, data->buf, data->size);

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	hypfs_dbfs_data_free(data);

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	return rc;

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}

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static long dbfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg)

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{

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	struct hypfs_dbfs_file *df = file_inode(file)->i_private;

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	long rc;

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	mutex_lock(&df->lock);

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	rc = df->unlocked_ioctl(file, cmd, arg);

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	mutex_unlock(&df->lock);

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	return rc;

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}

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static const struct file_operations dbfs_ops_ioctl = {

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	.read		= dbfs_read,

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	.unlocked_ioctl = dbfs_ioctl,

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};

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static const struct file_operations dbfs_ops = {

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	.read		= dbfs_read,

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};

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void hypfs_dbfs_create_file(struct hypfs_dbfs_file *df)

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{

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	const struct file_operations *fops = &dbfs_ops;

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	if (df->unlocked_ioctl && !security_locked_down(LOCKDOWN_DEBUGFS))

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		fops = &dbfs_ops_ioctl;

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	df->dentry = debugfs_create_file(df->name, 0400, dbfs_dir, df, fops);

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	mutex_init(&df->lock);

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}

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void hypfs_dbfs_remove_file(struct hypfs_dbfs_file *df)

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{

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	debugfs_remove(df->dentry);

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}

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static int __init hypfs_dbfs_init(void)

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{

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	int rc = -ENODATA;

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	dbfs_dir = debugfs_create_dir("s390_hypfs", NULL);

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	if (hypfs_diag_init())

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		goto fail_dbfs_exit;

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	if (hypfs_vm_init())

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		goto fail_hypfs_diag_exit;

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	hypfs_sprp_init();

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	if (hypfs_diag0c_init())

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		goto fail_hypfs_sprp_exit;

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	rc = hypfs_fs_init();

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	if (rc)

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		goto fail_hypfs_diag0c_exit;

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	return 0;

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fail_hypfs_diag0c_exit:

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	hypfs_diag0c_exit();

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fail_hypfs_sprp_exit:

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	hypfs_sprp_exit();

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	hypfs_vm_exit();

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fail_hypfs_diag_exit:

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	hypfs_diag_exit();

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	pr_err("Initialization of hypfs failed with rc=%i\n", rc);

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fail_dbfs_exit:

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	debugfs_remove(dbfs_dir);

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	return rc;

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}

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device_initcall(hypfs_dbfs_init)

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