arch/s390/hypfs/hypfs_dbfs.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Hypervisor filesystem for Linux on s390 - debugfs interface
   4  *
   5  * Copyright IBM Corp. 2010
   6  * Author(s): Michael Holzheu <[email protected]>
   7  */
   8
   9 #include <linux/slab.h>
  10 #include "hypfs.h"
  11
  12 static struct dentry *dbfs_dir;
  13
  14 static struct hypfs_dbfs_data *hypfs_dbfs_data_alloc(struct hypfs_dbfs_file *f)
  15 {
  16         struct hypfs_dbfs_data *data;
  17
  18         data = kmalloc(sizeof(*data), GFP_KERNEL);
  19         if (!data)
  20                 return NULL;
  21         data->dbfs_file = f;
  22         return data;
  23 }
  24
  25 static void hypfs_dbfs_data_free(struct hypfs_dbfs_data *data)
  26 {
  27         data->dbfs_file->data_free(data->buf_free_ptr);
  28         kfree(data);
  29 }
  30
  31 static ssize_t dbfs_read(struct file *file, char __user *buf,
  32                          size_t size, loff_t *ppos)
  33 {
  34         struct hypfs_dbfs_data *data;
  35         struct hypfs_dbfs_file *df;
  36         ssize_t rc;
  37
  38         if (*ppos != 0)
  39                 return 0;
  40
  41         df = file_inode(file)->i_private;
  42         if (mutex_lock_interruptible(&df->lock))
  43                 return -ERESTARTSYS;
  44
  45         data = hypfs_dbfs_data_alloc(df);
  46         if (!data) {
  47                 mutex_unlock(&df->lock);
  48                 return -ENOMEM;
  49         }
  50         rc = df->data_create(&data->buf, &data->buf_free_ptr, &data->size);
  51         if (rc) {
  52                 mutex_unlock(&df->lock);
  53                 kfree(data);
  54                 return rc;
  55         }
  56         mutex_unlock(&df->lock);
  57
  58         rc = simple_read_from_buffer(buf, size, ppos, data->buf, data->size);
  59         hypfs_dbfs_data_free(data);
  60         return rc;
  61 }
  62
  63 static long dbfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
  64 {
  65         struct hypfs_dbfs_file *df = file_inode(file)->i_private;
  66         long rc;
  67
  68         mutex_lock(&df->lock);
  69         if (df->unlocked_ioctl)
  70                 rc = df->unlocked_ioctl(file, cmd, arg);
  71         else
  72                 rc = -ENOTTY;
  73         mutex_unlock(&df->lock);
  74         return rc;
  75 }
  76
  77 static const struct file_operations dbfs_ops = {
  78         .read           = dbfs_read,
  79         .unlocked_ioctl = dbfs_ioctl,
  80 };
  81
  82 void hypfs_dbfs_create_file(struct hypfs_dbfs_file *df)
  83 {
  84         df->dentry = debugfs_create_file(df->name, 0400, dbfs_dir, df,
  85                                          &dbfs_ops);
  86         mutex_init(&df->lock);
  87 }
  88
  89 void hypfs_dbfs_remove_file(struct hypfs_dbfs_file *df)
  90 {
  91         debugfs_remove(df->dentry);
  92 }
  93
  94 static int __init hypfs_dbfs_init(void)
  95 {
  96         int rc = -ENODATA;
  97
  98         dbfs_dir = debugfs_create_dir("s390_hypfs", NULL);
  99         if (hypfs_diag_init())
 100                 goto fail_dbfs_exit;
 101         if (hypfs_vm_init())
 102                 goto fail_hypfs_diag_exit;
 103         hypfs_sprp_init();
 104         if (hypfs_diag0c_init())
 105                 goto fail_hypfs_sprp_exit;
 106         rc = hypfs_fs_init();
 107         if (rc)
 108                 goto fail_hypfs_diag0c_exit;
 109         return 0;
 110
 111 fail_hypfs_diag0c_exit:
 112         hypfs_diag0c_exit();
 113 fail_hypfs_sprp_exit:
 114         hypfs_sprp_exit();
 115         hypfs_vm_exit();
 116 fail_hypfs_diag_exit:
 117         hypfs_diag_exit();
 118         pr_err("Initialization of hypfs failed with rc=%i\n", rc);
 119 fail_dbfs_exit:
 120         debugfs_remove(dbfs_dir);
 121         return rc;
 122 }
 123 device_initcall(hypfs_dbfs_init)