1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Block device concurrent positioning ranges.
4 *
5 * Copyright (C) 2021 Western Digital Corporation or its Affiliates.
6 */
7 #include <linux/kernel.h>
8 #include <linux/blkdev.h>
9 #include <linux/slab.h>
10 #include <linux/init.h>
11
12 #include "blk.h"
13
14 static ssize_t
blk_ia_range_sector_show(struct blk_independent_access_range * iar,char * buf)15 blk_ia_range_sector_show(struct blk_independent_access_range *iar,
16 char *buf)
17 {
18 return sprintf(buf, "%llu\n", iar->sector);
19 }
20
21 static ssize_t
blk_ia_range_nr_sectors_show(struct blk_independent_access_range * iar,char * buf)22 blk_ia_range_nr_sectors_show(struct blk_independent_access_range *iar,
23 char *buf)
24 {
25 return sprintf(buf, "%llu\n", iar->nr_sectors);
26 }
27
28 struct blk_ia_range_sysfs_entry {
29 struct attribute attr;
30 ssize_t (*show)(struct blk_independent_access_range *iar, char *buf);
31 };
32
33 static struct blk_ia_range_sysfs_entry blk_ia_range_sector_entry = {
34 .attr = { .name = "sector", .mode = 0444 },
35 .show = blk_ia_range_sector_show,
36 };
37
38 static struct blk_ia_range_sysfs_entry blk_ia_range_nr_sectors_entry = {
39 .attr = { .name = "nr_sectors", .mode = 0444 },
40 .show = blk_ia_range_nr_sectors_show,
41 };
42
43 static struct attribute *blk_ia_range_attrs[] = {
44 &blk_ia_range_sector_entry.attr,
45 &blk_ia_range_nr_sectors_entry.attr,
46 NULL,
47 };
48 ATTRIBUTE_GROUPS(blk_ia_range);
49
blk_ia_range_sysfs_show(struct kobject * kobj,struct attribute * attr,char * buf)50 static ssize_t blk_ia_range_sysfs_show(struct kobject *kobj,
51 struct attribute *attr, char *buf)
52 {
53 struct blk_ia_range_sysfs_entry *entry =
54 container_of(attr, struct blk_ia_range_sysfs_entry, attr);
55 struct blk_independent_access_range *iar =
56 container_of(kobj, struct blk_independent_access_range, kobj);
57
58 return entry->show(iar, buf);
59 }
60
61 static const struct sysfs_ops blk_ia_range_sysfs_ops = {
62 .show = blk_ia_range_sysfs_show,
63 };
64
65 /*
66 * Independent access range entries are not freed individually, but alltogether
67 * with struct blk_independent_access_ranges and its array of ranges. Since
68 * kobject_add() takes a reference on the parent kobject contained in
69 * struct blk_independent_access_ranges, the array of independent access range
70 * entries cannot be freed until kobject_del() is called for all entries.
71 * So we do not need to do anything here, but still need this no-op release
72 * operation to avoid complaints from the kobject code.
73 */
blk_ia_range_sysfs_nop_release(struct kobject * kobj)74 static void blk_ia_range_sysfs_nop_release(struct kobject *kobj)
75 {
76 }
77
78 static struct kobj_type blk_ia_range_ktype = {
79 .sysfs_ops = &blk_ia_range_sysfs_ops,
80 .default_groups = blk_ia_range_groups,
81 .release = blk_ia_range_sysfs_nop_release,
82 };
83
84 /*
85 * This will be executed only after all independent access range entries are
86 * removed with kobject_del(), at which point, it is safe to free everything,
87 * including the array of ranges.
88 */
blk_ia_ranges_sysfs_release(struct kobject * kobj)89 static void blk_ia_ranges_sysfs_release(struct kobject *kobj)
90 {
91 struct blk_independent_access_ranges *iars =
92 container_of(kobj, struct blk_independent_access_ranges, kobj);
93
94 kfree(iars);
95 }
96
97 static struct kobj_type blk_ia_ranges_ktype = {
98 .release = blk_ia_ranges_sysfs_release,
99 };
100
101 /**
102 * disk_register_independent_access_ranges - register with sysfs a set of
103 * independent access ranges
104 * @disk: Target disk
105 *
106 * Register with sysfs a set of independent access ranges for @disk.
107 */
disk_register_independent_access_ranges(struct gendisk * disk)108 int disk_register_independent_access_ranges(struct gendisk *disk)
109 {
110 struct blk_independent_access_ranges *iars = disk->ia_ranges;
111 struct request_queue *q = disk->queue;
112 int i, ret;
113
114 lockdep_assert_held(&q->sysfs_dir_lock);
115 lockdep_assert_held(&q->sysfs_lock);
116
117 if (!iars)
118 return 0;
119
120 /*
121 * At this point, iars is the new set of sector access ranges that needs
122 * to be registered with sysfs.
123 */
124 WARN_ON(iars->sysfs_registered);
125 ret = kobject_init_and_add(&iars->kobj, &blk_ia_ranges_ktype,
126 &q->kobj, "%s", "independent_access_ranges");
127 if (ret) {
128 disk->ia_ranges = NULL;
129 kobject_put(&iars->kobj);
130 return ret;
131 }
132
133 for (i = 0; i < iars->nr_ia_ranges; i++) {
134 ret = kobject_init_and_add(&iars->ia_range[i].kobj,
135 &blk_ia_range_ktype, &iars->kobj,
136 "%d", i);
137 if (ret) {
138 while (--i >= 0)
139 kobject_del(&iars->ia_range[i].kobj);
140 kobject_del(&iars->kobj);
141 kobject_put(&iars->kobj);
142 return ret;
143 }
144 }
145
146 iars->sysfs_registered = true;
147
148 return 0;
149 }
150
disk_unregister_independent_access_ranges(struct gendisk * disk)151 void disk_unregister_independent_access_ranges(struct gendisk *disk)
152 {
153 struct request_queue *q = disk->queue;
154 struct blk_independent_access_ranges *iars = disk->ia_ranges;
155 int i;
156
157 lockdep_assert_held(&q->sysfs_dir_lock);
158 lockdep_assert_held(&q->sysfs_lock);
159
160 if (!iars)
161 return;
162
163 if (iars->sysfs_registered) {
164 for (i = 0; i < iars->nr_ia_ranges; i++)
165 kobject_del(&iars->ia_range[i].kobj);
166 kobject_del(&iars->kobj);
167 kobject_put(&iars->kobj);
168 } else {
169 kfree(iars);
170 }
171
172 disk->ia_ranges = NULL;
173 }
174
175 static struct blk_independent_access_range *
disk_find_ia_range(struct blk_independent_access_ranges * iars,sector_t sector)176 disk_find_ia_range(struct blk_independent_access_ranges *iars,
177 sector_t sector)
178 {
179 struct blk_independent_access_range *iar;
180 int i;
181
182 for (i = 0; i < iars->nr_ia_ranges; i++) {
183 iar = &iars->ia_range[i];
184 if (sector >= iar->sector &&
185 sector < iar->sector + iar->nr_sectors)
186 return iar;
187 }
188
189 return NULL;
190 }
191
disk_check_ia_ranges(struct gendisk * disk,struct blk_independent_access_ranges * iars)192 static bool disk_check_ia_ranges(struct gendisk *disk,
193 struct blk_independent_access_ranges *iars)
194 {
195 struct blk_independent_access_range *iar, *tmp;
196 sector_t capacity = get_capacity(disk);
197 sector_t sector = 0;
198 int i;
199
200 if (WARN_ON_ONCE(!iars->nr_ia_ranges))
201 return false;
202
203 /*
204 * While sorting the ranges in increasing LBA order, check that the
205 * ranges do not overlap, that there are no sector holes and that all
206 * sectors belong to one range.
207 */
208 for (i = 0; i < iars->nr_ia_ranges; i++) {
209 tmp = disk_find_ia_range(iars, sector);
210 if (!tmp || tmp->sector != sector) {
211 pr_warn("Invalid non-contiguous independent access ranges\n");
212 return false;
213 }
214
215 iar = &iars->ia_range[i];
216 if (tmp != iar) {
217 swap(iar->sector, tmp->sector);
218 swap(iar->nr_sectors, tmp->nr_sectors);
219 }
220
221 sector += iar->nr_sectors;
222 }
223
224 if (sector != capacity) {
225 pr_warn("Independent access ranges do not match disk capacity\n");
226 return false;
227 }
228
229 return true;
230 }
231
disk_ia_ranges_changed(struct gendisk * disk,struct blk_independent_access_ranges * new)232 static bool disk_ia_ranges_changed(struct gendisk *disk,
233 struct blk_independent_access_ranges *new)
234 {
235 struct blk_independent_access_ranges *old = disk->ia_ranges;
236 int i;
237
238 if (!old)
239 return true;
240
241 if (old->nr_ia_ranges != new->nr_ia_ranges)
242 return true;
243
244 for (i = 0; i < old->nr_ia_ranges; i++) {
245 if (new->ia_range[i].sector != old->ia_range[i].sector ||
246 new->ia_range[i].nr_sectors != old->ia_range[i].nr_sectors)
247 return true;
248 }
249
250 return false;
251 }
252
253 /**
254 * disk_alloc_independent_access_ranges - Allocate an independent access ranges
255 * data structure
256 * @disk: target disk
257 * @nr_ia_ranges: Number of independent access ranges
258 *
259 * Allocate a struct blk_independent_access_ranges structure with @nr_ia_ranges
260 * access range descriptors.
261 */
262 struct blk_independent_access_ranges *
disk_alloc_independent_access_ranges(struct gendisk * disk,int nr_ia_ranges)263 disk_alloc_independent_access_ranges(struct gendisk *disk, int nr_ia_ranges)
264 {
265 struct blk_independent_access_ranges *iars;
266
267 iars = kzalloc_node(struct_size(iars, ia_range, nr_ia_ranges),
268 GFP_KERNEL, disk->queue->node);
269 if (iars)
270 iars->nr_ia_ranges = nr_ia_ranges;
271 return iars;
272 }
273 EXPORT_SYMBOL_GPL(disk_alloc_independent_access_ranges);
274
275 /**
276 * disk_set_independent_access_ranges - Set a disk independent access ranges
277 * @disk: target disk
278 * @iars: independent access ranges structure
279 *
280 * Set the independent access ranges information of the request queue
281 * of @disk to @iars. If @iars is NULL and the independent access ranges
282 * structure already set is cleared. If there are no differences between
283 * @iars and the independent access ranges structure already set, @iars
284 * is freed.
285 */
disk_set_independent_access_ranges(struct gendisk * disk,struct blk_independent_access_ranges * iars)286 void disk_set_independent_access_ranges(struct gendisk *disk,
287 struct blk_independent_access_ranges *iars)
288 {
289 struct request_queue *q = disk->queue;
290
291 mutex_lock(&q->sysfs_dir_lock);
292 mutex_lock(&q->sysfs_lock);
293 if (iars && !disk_check_ia_ranges(disk, iars)) {
294 kfree(iars);
295 iars = NULL;
296 }
297 if (iars && !disk_ia_ranges_changed(disk, iars)) {
298 kfree(iars);
299 goto unlock;
300 }
301
302 /*
303 * This may be called for a registered queue. E.g. during a device
304 * revalidation. If that is the case, we need to unregister the old
305 * set of independent access ranges and register the new set. If the
306 * queue is not registered, registration of the device request queue
307 * will register the independent access ranges.
308 */
309 disk_unregister_independent_access_ranges(disk);
310 disk->ia_ranges = iars;
311 if (blk_queue_registered(q))
312 disk_register_independent_access_ranges(disk);
313 unlock:
314 mutex_unlock(&q->sysfs_lock);
315 mutex_unlock(&q->sysfs_dir_lock);
316 }
317 EXPORT_SYMBOL_GPL(disk_set_independent_access_ranges);
318
