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/major.h>
18 #include <linux/fs.h>
19 #include <linux/blkpg.h>
20 
21 #include <linux/uaccess.h>
22 
23 /* This is ugly... */
24 #define PRINTK_HEADER "dasd_gendisk:"
25 
26 #include "dasd_int.h"
27 
28 static struct lock_class_key dasd_bio_compl_lkclass;
29 
30 /*
31  * Allocate and register gendisk structure for device.
32  */
dasd_gendisk_alloc(struct dasd_block * block)33 int dasd_gendisk_alloc(struct dasd_block *block)
34 {
35 	struct gendisk *gdp;
36 	struct dasd_device *base;
37 	int len, rc;
38 
39 	/* Make sure the minor for this device exists. */
40 	base = block->base;
41 	if (base->devindex >= DASD_PER_MAJOR)
42 		return -EBUSY;
43 
44 	gdp = __alloc_disk_node(block->request_queue, NUMA_NO_NODE,
45 				&dasd_bio_compl_lkclass);
46 	if (!gdp)
47 		return -ENOMEM;
48 
49 	/* Initialize gendisk structure. */
50 	gdp->major = DASD_MAJOR;
51 	gdp->first_minor = base->devindex << DASD_PARTN_BITS;
52 	gdp->minors = 1 << DASD_PARTN_BITS;
53 	gdp->fops = &dasd_device_operations;
54 
55 	/*
56 	 * Set device name.
57 	 *   dasda - dasdz : 26 devices
58 	 *   dasdaa - dasdzz : 676 devices, added up = 702
59 	 *   dasdaaa - dasdzzz : 17576 devices, added up = 18278
60 	 *   dasdaaaa - dasdzzzz : 456976 devices, added up = 475252
61 	 */
62 	len = sprintf(gdp->disk_name, "dasd");
63 	if (base->devindex > 25) {
64 		if (base->devindex > 701) {
65 			if (base->devindex > 18277)
66 			        len += sprintf(gdp->disk_name + len, "%c",
67 					       'a'+(((base->devindex-18278)
68 						     /17576)%26));
69 			len += sprintf(gdp->disk_name + len, "%c",
70 				       'a'+(((base->devindex-702)/676)%26));
71 		}
72 		len += sprintf(gdp->disk_name + len, "%c",
73 			       'a'+(((base->devindex-26)/26)%26));
74 	}
75 	len += sprintf(gdp->disk_name + len, "%c", 'a'+(base->devindex%26));
76 
77 	if (base->features & DASD_FEATURE_READONLY ||
78 	    test_bit(DASD_FLAG_DEVICE_RO, &base->flags))
79 		set_disk_ro(gdp, 1);
80 	dasd_add_link_to_gendisk(gdp, base);
81 	block->gdp = gdp;
82 	set_capacity(block->gdp, 0);
83 
84 	rc = device_add_disk(&base->cdev->dev, block->gdp, NULL);
85 	if (rc) {
86 		dasd_gendisk_free(block);
87 		return rc;
88 	}
89 
90 	return 0;
91 }
92 
93 /*
94  * Unregister and free gendisk structure for device.
95  */
dasd_gendisk_free(struct dasd_block * block)96 void dasd_gendisk_free(struct dasd_block *block)
97 {
98 	if (block->gdp) {
99 		del_gendisk(block->gdp);
100 		block->gdp->private_data = NULL;
101 		put_disk(block->gdp);
102 		block->gdp = NULL;
103 	}
104 }
105 
106 /*
107  * Trigger a partition detection.
108  */
dasd_scan_partitions(struct dasd_block * block)109 int dasd_scan_partitions(struct dasd_block *block)
110 {
111 	struct block_device *bdev;
112 	int rc;
113 
114 	bdev = blkdev_get_by_dev(disk_devt(block->gdp), FMODE_READ, NULL);
115 	if (IS_ERR(bdev)) {
116 		DBF_DEV_EVENT(DBF_ERR, block->base,
117 			      "scan partitions error, blkdev_get returned %ld",
118 			      PTR_ERR(bdev));
119 		return -ENODEV;
120 	}
121 
122 	mutex_lock(&block->gdp->open_mutex);
123 	rc = bdev_disk_changed(block->gdp, false);
124 	mutex_unlock(&block->gdp->open_mutex);
125 	if (rc)
126 		DBF_DEV_EVENT(DBF_ERR, block->base,
127 				"scan partitions error, rc %d", rc);
128 
129 	/*
130 	 * Since the matching blkdev_put call to the blkdev_get in
131 	 * this function is not called before dasd_destroy_partitions
132 	 * the offline open_count limit needs to be increased from
133 	 * 0 to 1. This is done by setting device->bdev (see
134 	 * dasd_generic_set_offline). As long as the partition
135 	 * detection is running no offline should be allowed. That
136 	 * is why the assignment to device->bdev is done AFTER
137 	 * the BLKRRPART ioctl.
138 	 */
139 	block->bdev = bdev;
140 	return 0;
141 }
142 
143 /*
144  * Remove all inodes in the system for a device, delete the
145  * partitions and make device unusable by setting its size to zero.
146  */
dasd_destroy_partitions(struct dasd_block * block)147 void dasd_destroy_partitions(struct dasd_block *block)
148 {
149 	struct block_device *bdev;
150 
151 	/*
152 	 * Get the bdev pointer from the device structure and clear
153 	 * device->bdev to lower the offline open_count limit again.
154 	 */
155 	bdev = block->bdev;
156 	block->bdev = NULL;
157 
158 	mutex_lock(&bdev->bd_disk->open_mutex);
159 	bdev_disk_changed(bdev->bd_disk, true);
160 	mutex_unlock(&bdev->bd_disk->open_mutex);
161 
162 	/* Matching blkdev_put to the blkdev_get in dasd_scan_partitions. */
163 	blkdev_put(bdev, FMODE_READ);
164 }
165 
dasd_gendisk_init(void)166 int dasd_gendisk_init(void)
167 {
168 	int rc;
169 
170 	/* Register to static dasd major 94 */
171 	rc = register_blkdev(DASD_MAJOR, "dasd");
172 	if (rc != 0) {
173 		pr_warn("Registering the device driver with major number %d failed\n",
174 			DASD_MAJOR);
175 		return rc;
176 	}
177 	return 0;
178 }
179 
dasd_gendisk_exit(void)180 void dasd_gendisk_exit(void)
181 {
182 	unregister_blkdev(DASD_MAJOR, "dasd");
183 }
184