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git.proxmox.com Git - mirror_ubuntu-kernels.git/blob - block/holder.c
1 // SPDX-License-Identifier: GPL-2.0-only
2 #include <linux/blkdev.h>
3 #include <linux/slab.h>
5 struct bd_holder_disk
{
7 struct kobject
*holder_dir
;
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
->holder_dir
== bdev
->bd_holder_dir
)
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
));
33 * bd_link_disk_holder - create symlinks between holding disk and slave bdev
34 * @bdev: the claimed slave bdev
35 * @disk: the holding disk
37 * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
39 * This functions creates the following sysfs symlinks.
41 * - from "slaves" directory of the holder @disk to the claimed @bdev
42 * - from "holders" directory of the @bdev to the holder @disk
44 * For example, if /dev/dm-0 maps to /dev/sda and disk for dm-0 is
45 * passed to bd_link_disk_holder(), then:
47 * /sys/block/dm-0/slaves/sda --> /sys/block/sda
48 * /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
50 * The caller must have claimed @bdev before calling this function and
51 * ensure that both @bdev and @disk are valid during the creation and
52 * lifetime of these symlinks.
58 * 0 on success, -errno on failure.
60 int bd_link_disk_holder(struct block_device
*bdev
, struct gendisk
*disk
)
62 struct bd_holder_disk
*holder
;
65 if (WARN_ON_ONCE(!disk
->slave_dir
))
68 if (bdev
->bd_disk
== disk
)
72 * del_gendisk drops the initial reference to bd_holder_dir, so we
73 * need to keep our own here to allow for cleanup past that point.
75 mutex_lock(&bdev
->bd_disk
->open_mutex
);
76 if (!disk_live(bdev
->bd_disk
)) {
77 mutex_unlock(&bdev
->bd_disk
->open_mutex
);
80 kobject_get(bdev
->bd_holder_dir
);
81 mutex_unlock(&bdev
->bd_disk
->open_mutex
);
83 mutex_lock(&disk
->open_mutex
);
84 WARN_ON_ONCE(!bdev
->bd_holder
);
86 holder
= bd_find_holder_disk(bdev
, disk
);
88 kobject_put(bdev
->bd_holder_dir
);
93 holder
= kzalloc(sizeof(*holder
), GFP_KERNEL
);
99 INIT_LIST_HEAD(&holder
->list
);
101 holder
->holder_dir
= bdev
->bd_holder_dir
;
103 ret
= add_symlink(disk
->slave_dir
, bdev_kobj(bdev
));
105 goto out_free_holder
;
106 ret
= add_symlink(bdev
->bd_holder_dir
, &disk_to_dev(disk
)->kobj
);
108 goto out_del_symlink
;
109 list_add(&holder
->list
, &disk
->slave_bdevs
);
111 mutex_unlock(&disk
->open_mutex
);
115 del_symlink(disk
->slave_dir
, bdev_kobj(bdev
));
119 mutex_unlock(&disk
->open_mutex
);
121 kobject_put(bdev
->bd_holder_dir
);
124 EXPORT_SYMBOL_GPL(bd_link_disk_holder
);
127 * bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder()
128 * @bdev: the calimed slave bdev
129 * @disk: the holding disk
131 * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
136 void bd_unlink_disk_holder(struct block_device
*bdev
, struct gendisk
*disk
)
138 struct bd_holder_disk
*holder
;
140 if (WARN_ON_ONCE(!disk
->slave_dir
))
143 mutex_lock(&disk
->open_mutex
);
144 holder
= bd_find_holder_disk(bdev
, disk
);
145 if (!WARN_ON_ONCE(holder
== NULL
) && !--holder
->refcnt
) {
146 del_symlink(disk
->slave_dir
, bdev_kobj(bdev
));
147 del_symlink(holder
->holder_dir
, &disk_to_dev(disk
)->kobj
);
148 kobject_put(holder
->holder_dir
);
149 list_del_init(&holder
->list
);
152 mutex_unlock(&disk
->open_mutex
);
154 EXPORT_SYMBOL_GPL(bd_unlink_disk_holder
);