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  */
dasd_gendisk_alloc(struct dasd_block * block)30 int 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  */
dasd_gendisk_free(struct dasd_block * block)86 void 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  */
dasd_scan_partitions(struct dasd_block * block)99 int dasd_scan_partitions(struct dasd_block *block)
100 {
101 	struct block_device *bdev;
102 	int rc;
103 
104 	bdev = bdget_disk(block->gdp, 0);
105 	if (!bdev) {
106 		DBF_DEV_EVENT(DBF_ERR, block->base, "%s",
107 			      "scan partitions error, bdget returned NULL");
108 		return -ENODEV;
109 	}
110 
111 	rc = blkdev_get(bdev, FMODE_READ, NULL);
112 	if (rc < 0) {
113 		DBF_DEV_EVENT(DBF_ERR, block->base,
114 			      "scan partitions error, blkdev_get returned %d",
115 			      rc);
116 		return -ENODEV;
117 	}
118 
119 	rc = blkdev_reread_part(bdev);
120 	if (rc)
121 		DBF_DEV_EVENT(DBF_ERR, block->base,
122 				"scan partitions error, rc %d", rc);
123 
124 	/*
125 	 * Since the matching blkdev_put call to the blkdev_get in
126 	 * this function is not called before dasd_destroy_partitions
127 	 * the offline open_count limit needs to be increased from
128 	 * 0 to 1. This is done by setting device->bdev (see
129 	 * dasd_generic_set_offline). As long as the partition
130 	 * detection is running no offline should be allowed. That
131 	 * is why the assignment to device->bdev is done AFTER
132 	 * the BLKRRPART ioctl.
133 	 */
134 	block->bdev = bdev;
135 	return 0;
136 }
137 
138 /*
139  * Remove all inodes in the system for a device, delete the
140  * partitions and make device unusable by setting its size to zero.
141  */
dasd_destroy_partitions(struct dasd_block * block)142 void dasd_destroy_partitions(struct dasd_block *block)
143 {
144 	/* The two structs have 168/176 byte on 31/64 bit. */
145 	struct blkpg_partition bpart;
146 	struct blkpg_ioctl_arg barg;
147 	struct block_device *bdev;
148 
149 	/*
150 	 * Get the bdev pointer from the device structure and clear
151 	 * device->bdev to lower the offline open_count limit again.
152 	 */
153 	bdev = block->bdev;
154 	block->bdev = NULL;
155 
156 	/*
157 	 * See fs/partition/check.c:delete_partition
158 	 * Can't call delete_partitions directly. Use ioctl.
159 	 * The ioctl also does locking and invalidation.
160 	 */
161 	memset(&bpart, 0, sizeof(struct blkpg_partition));
162 	memset(&barg, 0, sizeof(struct blkpg_ioctl_arg));
163 	barg.data = (void __force __user *) &bpart;
164 	barg.op = BLKPG_DEL_PARTITION;
165 	for (bpart.pno = block->gdp->minors - 1; bpart.pno > 0; bpart.pno--)
166 		ioctl_by_bdev(bdev, BLKPG, (unsigned long) &barg);
167 
168 	invalidate_partition(block->gdp, 0);
169 	/* Matching blkdev_put to the blkdev_get in dasd_scan_partitions. */
170 	blkdev_put(bdev, FMODE_READ);
171 	set_capacity(block->gdp, 0);
172 }
173 
dasd_gendisk_init(void)174 int dasd_gendisk_init(void)
175 {
176 	int rc;
177 
178 	/* Register to static dasd major 94 */
179 	rc = register_blkdev(DASD_MAJOR, "dasd");
180 	if (rc != 0) {
181 		pr_warn("Registering the device driver with major number %d failed\n",
182 			DASD_MAJOR);
183 		return rc;
184 	}
185 	return 0;
186 }
187 
dasd_gendisk_exit(void)188 void dasd_gendisk_exit(void)
189 {
190 	unregister_blkdev(DASD_MAJOR, "dasd");
191 }
192