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git.proxmox.com Git - mirror_ubuntu-jammy-kernel.git/blob - block/holder.c
1 // SPDX-License-Identifier: GPL-2.0-only
2 #include <linux/genhd.h>
3 #include <linux/slab.h>
5 struct bd_holder_disk
{
7 struct block_device
*bdev
;
11 static struct bd_holder_disk
*bd_find_holder_disk(struct block_device
*bdev
,
14 struct bd_holder_disk
*holder
;
16 list_for_each_entry(holder
, &disk
->slave_bdevs
, list
)
17 if (holder
->bdev
== bdev
)
22 static int add_symlink(struct kobject
*from
, struct kobject
*to
)
24 return sysfs_create_link(from
, to
, kobject_name(to
));
27 static void del_symlink(struct kobject
*from
, struct kobject
*to
)
29 sysfs_remove_link(from
, kobject_name(to
));
32 static int __link_disk_holder(struct block_device
*bdev
, struct gendisk
*disk
)
36 ret
= add_symlink(disk
->slave_dir
, bdev_kobj(bdev
));
39 ret
= add_symlink(bdev
->bd_holder_dir
, &disk_to_dev(disk
)->kobj
);
41 del_symlink(disk
->slave_dir
, bdev_kobj(bdev
));
46 * bd_link_disk_holder - create symlinks between holding disk and slave bdev
47 * @bdev: the claimed slave bdev
48 * @disk: the holding disk
50 * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
52 * This functions creates the following sysfs symlinks.
54 * - from "slaves" directory of the holder @disk to the claimed @bdev
55 * - from "holders" directory of the @bdev to the holder @disk
57 * For example, if /dev/dm-0 maps to /dev/sda and disk for dm-0 is
58 * passed to bd_link_disk_holder(), then:
60 * /sys/block/dm-0/slaves/sda --> /sys/block/sda
61 * /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
63 * The caller must have claimed @bdev before calling this function and
64 * ensure that both @bdev and @disk are valid during the creation and
65 * lifetime of these symlinks.
71 * 0 on success, -errno on failure.
73 int bd_link_disk_holder(struct block_device
*bdev
, struct gendisk
*disk
)
75 struct bd_holder_disk
*holder
;
78 mutex_lock(&disk
->open_mutex
);
80 WARN_ON_ONCE(!bdev
->bd_holder
);
82 /* FIXME: remove the following once add_disk() handles errors */
83 if (WARN_ON(!bdev
->bd_holder_dir
))
86 holder
= bd_find_holder_disk(bdev
, disk
);
92 holder
= kzalloc(sizeof(*holder
), GFP_KERNEL
);
98 INIT_LIST_HEAD(&holder
->list
);
101 if (disk
->slave_dir
) {
102 ret
= __link_disk_holder(bdev
, disk
);
109 list_add(&holder
->list
, &disk
->slave_bdevs
);
111 * del_gendisk drops the initial reference to bd_holder_dir, so we need
112 * to keep our own here to allow for cleanup past that point.
114 kobject_get(bdev
->bd_holder_dir
);
117 mutex_unlock(&disk
->open_mutex
);
120 EXPORT_SYMBOL_GPL(bd_link_disk_holder
);
122 static void __unlink_disk_holder(struct block_device
*bdev
,
123 struct gendisk
*disk
)
125 del_symlink(disk
->slave_dir
, bdev_kobj(bdev
));
126 del_symlink(bdev
->bd_holder_dir
, &disk_to_dev(disk
)->kobj
);
130 * bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder()
131 * @bdev: the calimed slave bdev
132 * @disk: the holding disk
134 * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
139 void bd_unlink_disk_holder(struct block_device
*bdev
, struct gendisk
*disk
)
141 struct bd_holder_disk
*holder
;
143 mutex_lock(&disk
->open_mutex
);
144 holder
= bd_find_holder_disk(bdev
, disk
);
145 if (!WARN_ON_ONCE(holder
== NULL
) && !--holder
->refcnt
) {
147 __unlink_disk_holder(bdev
, disk
);
148 kobject_put(bdev
->bd_holder_dir
);
149 list_del_init(&holder
->list
);
152 mutex_unlock(&disk
->open_mutex
);
154 EXPORT_SYMBOL_GPL(bd_unlink_disk_holder
);
156 int bd_register_pending_holders(struct gendisk
*disk
)
158 struct bd_holder_disk
*holder
;
161 mutex_lock(&disk
->open_mutex
);
162 list_for_each_entry(holder
, &disk
->slave_bdevs
, list
) {
163 ret
= __link_disk_holder(holder
->bdev
, disk
);
167 mutex_unlock(&disk
->open_mutex
);
171 list_for_each_entry_continue_reverse(holder
, &disk
->slave_bdevs
, list
)
172 __unlink_disk_holder(holder
->bdev
, disk
);
173 mutex_unlock(&disk
->open_mutex
);