1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Author(s)......: Holger Smolinski <Holger.Smolinski@de.ibm.com>
4 *		    Horst Hummel <Horst.Hummel@de.ibm.com>
5 *		    Carsten Otte <Cotte@de.ibm.com>
6 *		    Martin Schwidefsky <schwidefsky@de.ibm.com>
7 * Bugreports.to..: <Linux390@de.ibm.com>
8 * Copyright IBM Corp. 1999, 2001
9 *
10 * gendisk related functions for the dasd driver.
11 *
12 */
13
14#define KMSG_COMPONENT "dasd"
15
16#include <linux/interrupt.h>
17#include <linux/fs.h>
18#include <linux/blkpg.h>
19
20#include <linux/uaccess.h>
21
22/* This is ugly... */
23#define PRINTK_HEADER "dasd_gendisk:"
24
25#include "dasd_int.h"
26
27/*
28 * Allocate and register gendisk structure for device.
29 */
30int dasd_gendisk_alloc(struct dasd_block *block)
31{
32	struct gendisk *gdp;
33	struct dasd_device *base;
34	int len;
35
36	/* Make sure the minor for this device exists. */
37	base = block->base;
38	if (base->devindex >= DASD_PER_MAJOR)
39		return -EBUSY;
40
41	gdp = alloc_disk(1 << DASD_PARTN_BITS);
42	if (!gdp)
43		return -ENOMEM;
44
45	/* Initialize gendisk structure. */
46	gdp->major = DASD_MAJOR;
47	gdp->first_minor = base->devindex << DASD_PARTN_BITS;
48	gdp->fops = &dasd_device_operations;
49
50	/*
51	 * Set device name.
52	 *   dasda - dasdz : 26 devices
53	 *   dasdaa - dasdzz : 676 devices, added up = 702
54	 *   dasdaaa - dasdzzz : 17576 devices, added up = 18278
55	 *   dasdaaaa - dasdzzzz : 456976 devices, added up = 475252
56	 */
57	len = sprintf(gdp->disk_name, "dasd");
58	if (base->devindex > 25) {
59		if (base->devindex > 701) {
60			if (base->devindex > 18277)
61			        len += sprintf(gdp->disk_name + len, "%c",
62					       'a'+(((base->devindex-18278)
63						     /17576)%26));
64			len += sprintf(gdp->disk_name + len, "%c",
65				       'a'+(((base->devindex-702)/676)%26));
66		}
67		len += sprintf(gdp->disk_name + len, "%c",
68			       'a'+(((base->devindex-26)/26)%26));
69	}
70	len += sprintf(gdp->disk_name + len, "%c", 'a'+(base->devindex%26));
71
72	if (base->features & DASD_FEATURE_READONLY ||
73	    test_bit(DASD_FLAG_DEVICE_RO, &base->flags))
74		set_disk_ro(gdp, 1);
75	dasd_add_link_to_gendisk(gdp, base);
76	gdp->queue = block->request_queue;
77	block->gdp = gdp;
78	set_capacity(block->gdp, 0);
79	device_add_disk(&base->cdev->dev, block->gdp, NULL);
80	return 0;
81}
82
83/*
84 * Unregister and free gendisk structure for device.
85 */
86void dasd_gendisk_free(struct dasd_block *block)
87{
88	if (block->gdp) {
89		del_gendisk(block->gdp);
90		block->gdp->private_data = NULL;
91		put_disk(block->gdp);
92		block->gdp = NULL;
93	}
94}
95
96/*
97 * Trigger a partition detection.
98 */
99int dasd_scan_partitions(struct dasd_block *block)
100{
101	struct block_device *bdev;
102	int rc;
103
104	bdev = blkdev_get_by_dev(disk_devt(block->gdp), FMODE_READ, NULL);
105	if (IS_ERR(bdev)) {
106		DBF_DEV_EVENT(DBF_ERR, block->base,
107			      "scan partitions error, blkdev_get returned %ld",
108			      PTR_ERR(bdev));
109		return -ENODEV;
110	}
111
112	mutex_lock(&bdev->bd_mutex);
113	rc = bdev_disk_changed(bdev, false);
114	mutex_unlock(&bdev->bd_mutex);
115	if (rc)
116		DBF_DEV_EVENT(DBF_ERR, block->base,
117				"scan partitions error, rc %d", rc);
118
119	/*
120	 * Since the matching blkdev_put call to the blkdev_get in
121	 * this function is not called before dasd_destroy_partitions
122	 * the offline open_count limit needs to be increased from
123	 * 0 to 1. This is done by setting device->bdev (see
124	 * dasd_generic_set_offline). As long as the partition
125	 * detection is running no offline should be allowed. That
126	 * is why the assignment to device->bdev is done AFTER
127	 * the BLKRRPART ioctl.
128	 */
129	block->bdev = bdev;
130	return 0;
131}
132
133/*
134 * Remove all inodes in the system for a device, delete the
135 * partitions and make device unusable by setting its size to zero.
136 */
137void dasd_destroy_partitions(struct dasd_block *block)
138{
139	struct block_device *bdev;
140
141	/*
142	 * Get the bdev pointer from the device structure and clear
143	 * device->bdev to lower the offline open_count limit again.
144	 */
145	bdev = block->bdev;
146	block->bdev = NULL;
147
148	mutex_lock(&bdev->bd_mutex);
149	blk_drop_partitions(bdev);
150	mutex_unlock(&bdev->bd_mutex);
151
152	/* Matching blkdev_put to the blkdev_get in dasd_scan_partitions. */
153	blkdev_put(bdev, FMODE_READ);
154	set_capacity(block->gdp, 0);
155}
156
157int dasd_gendisk_init(void)
158{
159	int rc;
160
161	/* Register to static dasd major 94 */
162	rc = register_blkdev(DASD_MAJOR, "dasd");
163	if (rc != 0) {
164		pr_warn("Registering the device driver with major number %d failed\n",
165			DASD_MAJOR);
166		return rc;
167	}
168	return 0;
169}
170
171void dasd_gendisk_exit(void)
172{
173	unregister_blkdev(DASD_MAJOR, "dasd");
174}
175