xref: /openbmc/linux/block/blk-ia-ranges.c (revision 35d4a3c6) 
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
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
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 
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  */
74 static void blk_ia_range_sysfs_nop_release(struct kobject *kobj)
75 {
76 }
77 
78 static const 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  */
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 const 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  */
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 				   &disk->queue_kobj, "%s",
127 				   "independent_access_ranges");
128 	if (ret) {
129 		disk->ia_ranges = NULL;
130 		kobject_put(&iars->kobj);
131 		return ret;
132 	}
133 
134 	for (i = 0; i < iars->nr_ia_ranges; i++) {
135 		ret = kobject_init_and_add(&iars->ia_range[i].kobj,
136 					   &blk_ia_range_ktype, &iars->kobj,
137 					   "%d", i);
138 		if (ret) {
139 			while (--i >= 0)
140 				kobject_del(&iars->ia_range[i].kobj);
141 			kobject_del(&iars->kobj);
142 			kobject_put(&iars->kobj);
143 			return ret;
144 		}
145 	}
146 
147 	iars->sysfs_registered = true;
148 
149 	return 0;
150 }
151 
152 void disk_unregister_independent_access_ranges(struct gendisk *disk)
153 {
154 	struct request_queue *q = disk->queue;
155 	struct blk_independent_access_ranges *iars = disk->ia_ranges;
156 	int i;
157 
158 	lockdep_assert_held(&q->sysfs_dir_lock);
159 	lockdep_assert_held(&q->sysfs_lock);
160 
161 	if (!iars)
162 		return;
163 
164 	if (iars->sysfs_registered) {
165 		for (i = 0; i < iars->nr_ia_ranges; i++)
166 			kobject_del(&iars->ia_range[i].kobj);
167 		kobject_del(&iars->kobj);
168 		kobject_put(&iars->kobj);
169 	} else {
170 		kfree(iars);
171 	}
172 
173 	disk->ia_ranges = NULL;
174 }
175 
176 static struct blk_independent_access_range *
177 disk_find_ia_range(struct blk_independent_access_ranges *iars,
178 		  sector_t sector)
179 {
180 	struct blk_independent_access_range *iar;
181 	int i;
182 
183 	for (i = 0; i < iars->nr_ia_ranges; i++) {
184 		iar = &iars->ia_range[i];
185 		if (sector >= iar->sector &&
186 		    sector < iar->sector + iar->nr_sectors)
187 			return iar;
188 	}
189 
190 	return NULL;
191 }
192 
193 static bool disk_check_ia_ranges(struct gendisk *disk,
194 				struct blk_independent_access_ranges *iars)
195 {
196 	struct blk_independent_access_range *iar, *tmp;
197 	sector_t capacity = get_capacity(disk);
198 	sector_t sector = 0;
199 	int i;
200 
201 	if (WARN_ON_ONCE(!iars->nr_ia_ranges))
202 		return false;
203 
204 	/*
205 	 * While sorting the ranges in increasing LBA order, check that the
206 	 * ranges do not overlap, that there are no sector holes and that all
207 	 * sectors belong to one range.
208 	 */
209 	for (i = 0; i < iars->nr_ia_ranges; i++) {
210 		tmp = disk_find_ia_range(iars, sector);
211 		if (!tmp || tmp->sector != sector) {
212 			pr_warn("Invalid non-contiguous independent access ranges\n");
213 			return false;
214 		}
215 
216 		iar = &iars->ia_range[i];
217 		if (tmp != iar) {
218 			swap(iar->sector, tmp->sector);
219 			swap(iar->nr_sectors, tmp->nr_sectors);
220 		}
221 
222 		sector += iar->nr_sectors;
223 	}
224 
225 	if (sector != capacity) {
226 		pr_warn("Independent access ranges do not match disk capacity\n");
227 		return false;
228 	}
229 
230 	return true;
231 }
232 
233 static bool disk_ia_ranges_changed(struct gendisk *disk,
234 				   struct blk_independent_access_ranges *new)
235 {
236 	struct blk_independent_access_ranges *old = disk->ia_ranges;
237 	int i;
238 
239 	if (!old)
240 		return true;
241 
242 	if (old->nr_ia_ranges != new->nr_ia_ranges)
243 		return true;
244 
245 	for (i = 0; i < old->nr_ia_ranges; i++) {
246 		if (new->ia_range[i].sector != old->ia_range[i].sector ||
247 		    new->ia_range[i].nr_sectors != old->ia_range[i].nr_sectors)
248 			return true;
249 	}
250 
251 	return false;
252 }
253 
254 /**
255  * disk_alloc_independent_access_ranges - Allocate an independent access ranges
256  *                                        data structure
257  * @disk:		target disk
258  * @nr_ia_ranges:	Number of independent access ranges
259  *
260  * Allocate a struct blk_independent_access_ranges structure with @nr_ia_ranges
261  * access range descriptors.
262  */
263 struct blk_independent_access_ranges *
264 disk_alloc_independent_access_ranges(struct gendisk *disk, int nr_ia_ranges)
265 {
266 	struct blk_independent_access_ranges *iars;
267 
268 	iars = kzalloc_node(struct_size(iars, ia_range, nr_ia_ranges),
269 			    GFP_KERNEL, disk->queue->node);
270 	if (iars)
271 		iars->nr_ia_ranges = nr_ia_ranges;
272 	return iars;
273 }
274 EXPORT_SYMBOL_GPL(disk_alloc_independent_access_ranges);
275 
276 /**
277  * disk_set_independent_access_ranges - Set a disk independent access ranges
278  * @disk:	target disk
279  * @iars:	independent access ranges structure
280  *
281  * Set the independent access ranges information of the request queue
282  * of @disk to @iars. If @iars is NULL and the independent access ranges
283  * structure already set is cleared. If there are no differences between
284  * @iars and the independent access ranges structure already set, @iars
285  * is freed.
286  */
287 void disk_set_independent_access_ranges(struct gendisk *disk,
288 				struct blk_independent_access_ranges *iars)
289 {
290 	struct request_queue *q = disk->queue;
291 
292 	mutex_lock(&q->sysfs_dir_lock);
293 	mutex_lock(&q->sysfs_lock);
294 	if (iars && !disk_check_ia_ranges(disk, iars)) {
295 		kfree(iars);
296 		iars = NULL;
297 	}
298 	if (iars && !disk_ia_ranges_changed(disk, iars)) {
299 		kfree(iars);
300 		goto unlock;
301 	}
302 
303 	/*
304 	 * This may be called for a registered queue. E.g. during a device
305 	 * revalidation. If that is the case, we need to unregister the old
306 	 * set of independent access ranges and register the new set. If the
307 	 * queue is not registered, registration of the device request queue
308 	 * will register the independent access ranges.
309 	 */
310 	disk_unregister_independent_access_ranges(disk);
311 	disk->ia_ranges = iars;
312 	if (blk_queue_registered(q))
313 		disk_register_independent_access_ranges(disk);
314 unlock:
315 	mutex_unlock(&q->sysfs_lock);
316 	mutex_unlock(&q->sysfs_dir_lock);
317 }
318 EXPORT_SYMBOL_GPL(disk_set_independent_access_ranges);
319