1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
|
// SPDX-License-Identifier: GPL-2.0-only
#include <linux/blkdev.h>
#include <linux/slab.h>
struct bd_holder_disk {
struct list_head list;
struct block_device *bdev;
int refcnt;
};
static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev,
struct gendisk *disk)
{
struct bd_holder_disk *holder;
list_for_each_entry(holder, &disk->slave_bdevs, list)
if (holder->bdev == bdev)
return holder;
return NULL;
}
static int add_symlink(struct kobject *from, struct kobject *to)
{
return sysfs_create_link(from, to, kobject_name(to));
}
static void del_symlink(struct kobject *from, struct kobject *to)
{
sysfs_remove_link(from, kobject_name(to));
}
static int __link_disk_holder(struct block_device *bdev, struct gendisk *disk)
{
int ret;
ret = add_symlink(disk->slave_dir, bdev_kobj(bdev));
if (ret)
return ret;
ret = add_symlink(bdev->bd_holder_dir, &disk_to_dev(disk)->kobj);
if (ret)
del_symlink(disk->slave_dir, bdev_kobj(bdev));
return ret;
}
/**
* bd_link_disk_holder - create symlinks between holding disk and slave bdev
* @bdev: the claimed slave bdev
* @disk: the holding disk
*
* DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
*
* This functions creates the following sysfs symlinks.
*
* - from "slaves" directory of the holder @disk to the claimed @bdev
* - from "holders" directory of the @bdev to the holder @disk
*
* For example, if /dev/dm-0 maps to /dev/sda and disk for dm-0 is
* passed to bd_link_disk_holder(), then:
*
* /sys/block/dm-0/slaves/sda --> /sys/block/sda
* /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
*
* The caller must have claimed @bdev before calling this function and
* ensure that both @bdev and @disk are valid during the creation and
* lifetime of these symlinks.
*
* CONTEXT:
* Might sleep.
*
* RETURNS:
* 0 on success, -errno on failure.
*/
int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
{
struct bd_holder_disk *holder;
int ret = 0;
mutex_lock(&disk->open_mutex);
WARN_ON_ONCE(!bdev->bd_holder);
holder = bd_find_holder_disk(bdev, disk);
if (holder) {
holder->refcnt++;
goto out_unlock;
}
holder = kzalloc(sizeof(*holder), GFP_KERNEL);
if (!holder) {
ret = -ENOMEM;
goto out_unlock;
}
INIT_LIST_HEAD(&holder->list);
holder->bdev = bdev;
holder->refcnt = 1;
if (disk->slave_dir) {
ret = __link_disk_holder(bdev, disk);
if (ret) {
kfree(holder);
goto out_unlock;
}
}
list_add(&holder->list, &disk->slave_bdevs);
/*
* del_gendisk drops the initial reference to bd_holder_dir, so we need
* to keep our own here to allow for cleanup past that point.
*/
kobject_get(bdev->bd_holder_dir);
out_unlock:
mutex_unlock(&disk->open_mutex);
return ret;
}
EXPORT_SYMBOL_GPL(bd_link_disk_holder);
static void __unlink_disk_holder(struct block_device *bdev,
struct gendisk *disk)
{
del_symlink(disk->slave_dir, bdev_kobj(bdev));
del_symlink(bdev->bd_holder_dir, &disk_to_dev(disk)->kobj);
}
/**
* bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder()
* @bdev: the calimed slave bdev
* @disk: the holding disk
*
* DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
*
* CONTEXT:
* Might sleep.
*/
void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
{
struct bd_holder_disk *holder;
mutex_lock(&disk->open_mutex);
holder = bd_find_holder_disk(bdev, disk);
if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) {
if (disk->slave_dir)
__unlink_disk_holder(bdev, disk);
kobject_put(bdev->bd_holder_dir);
list_del_init(&holder->list);
kfree(holder);
}
mutex_unlock(&disk->open_mutex);
}
EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
int bd_register_pending_holders(struct gendisk *disk)
{
struct bd_holder_disk *holder;
int ret;
mutex_lock(&disk->open_mutex);
list_for_each_entry(holder, &disk->slave_bdevs, list) {
ret = __link_disk_holder(holder->bdev, disk);
if (ret)
goto out_undo;
}
mutex_unlock(&disk->open_mutex);
return 0;
out_undo:
list_for_each_entry_continue_reverse(holder, &disk->slave_bdevs, list)
__unlink_disk_holder(holder->bdev, disk);
mutex_unlock(&disk->open_mutex);
return ret;
}
|
