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174 lines
4.2 KiB
174 lines
4.2 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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#include <linux/genhd.h> |
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struct bd_holder_disk { |
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struct list_head list; |
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struct block_device *bdev; |
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int refcnt; |
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}; |
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static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev, |
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struct gendisk *disk) |
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{ |
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struct bd_holder_disk *holder; |
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list_for_each_entry(holder, &disk->slave_bdevs, list) |
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if (holder->bdev == bdev) |
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return holder; |
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return NULL; |
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} |
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static int add_symlink(struct kobject *from, struct kobject *to) |
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{ |
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return sysfs_create_link(from, to, kobject_name(to)); |
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} |
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static void del_symlink(struct kobject *from, struct kobject *to) |
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{ |
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sysfs_remove_link(from, kobject_name(to)); |
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} |
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static int __link_disk_holder(struct block_device *bdev, struct gendisk *disk) |
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{ |
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int ret; |
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ret = add_symlink(disk->slave_dir, bdev_kobj(bdev)); |
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if (ret) |
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return ret; |
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ret = add_symlink(bdev->bd_holder_dir, &disk_to_dev(disk)->kobj); |
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if (ret) |
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del_symlink(disk->slave_dir, bdev_kobj(bdev)); |
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return ret; |
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} |
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/** |
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* bd_link_disk_holder - create symlinks between holding disk and slave bdev |
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* @bdev: the claimed slave bdev |
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* @disk: the holding disk |
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* |
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* DON'T USE THIS UNLESS YOU'RE ALREADY USING IT. |
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* |
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* This functions creates the following sysfs symlinks. |
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* |
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* - from "slaves" directory of the holder @disk to the claimed @bdev |
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* - from "holders" directory of the @bdev to the holder @disk |
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* |
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* For example, if /dev/dm-0 maps to /dev/sda and disk for dm-0 is |
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* passed to bd_link_disk_holder(), then: |
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* |
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* /sys/block/dm-0/slaves/sda --> /sys/block/sda |
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* /sys/block/sda/holders/dm-0 --> /sys/block/dm-0 |
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* |
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* The caller must have claimed @bdev before calling this function and |
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* ensure that both @bdev and @disk are valid during the creation and |
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* lifetime of these symlinks. |
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* |
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* CONTEXT: |
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* Might sleep. |
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* |
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* RETURNS: |
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* 0 on success, -errno on failure. |
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*/ |
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int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk) |
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{ |
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struct bd_holder_disk *holder; |
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int ret = 0; |
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mutex_lock(&disk->open_mutex); |
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WARN_ON_ONCE(!bdev->bd_holder); |
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/* FIXME: remove the following once add_disk() handles errors */ |
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if (WARN_ON(!bdev->bd_holder_dir)) |
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goto out_unlock; |
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holder = bd_find_holder_disk(bdev, disk); |
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if (holder) { |
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holder->refcnt++; |
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goto out_unlock; |
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} |
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holder = kzalloc(sizeof(*holder), GFP_KERNEL); |
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if (!holder) { |
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ret = -ENOMEM; |
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goto out_unlock; |
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} |
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INIT_LIST_HEAD(&holder->list); |
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holder->bdev = bdev; |
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holder->refcnt = 1; |
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if (disk->slave_dir) { |
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ret = __link_disk_holder(bdev, disk); |
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if (ret) { |
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kfree(holder); |
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goto out_unlock; |
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} |
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} |
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list_add(&holder->list, &disk->slave_bdevs); |
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/* |
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* del_gendisk drops the initial reference to bd_holder_dir, so we need |
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* to keep our own here to allow for cleanup past that point. |
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*/ |
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kobject_get(bdev->bd_holder_dir); |
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out_unlock: |
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mutex_unlock(&disk->open_mutex); |
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return ret; |
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} |
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EXPORT_SYMBOL_GPL(bd_link_disk_holder); |
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static void __unlink_disk_holder(struct block_device *bdev, |
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struct gendisk *disk) |
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{ |
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del_symlink(disk->slave_dir, bdev_kobj(bdev)); |
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del_symlink(bdev->bd_holder_dir, &disk_to_dev(disk)->kobj); |
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} |
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/** |
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* bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder() |
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* @bdev: the calimed slave bdev |
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* @disk: the holding disk |
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* |
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* DON'T USE THIS UNLESS YOU'RE ALREADY USING IT. |
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* |
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* CONTEXT: |
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* Might sleep. |
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*/ |
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void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk) |
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{ |
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struct bd_holder_disk *holder; |
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mutex_lock(&disk->open_mutex); |
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holder = bd_find_holder_disk(bdev, disk); |
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if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) { |
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if (disk->slave_dir) |
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__unlink_disk_holder(bdev, disk); |
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kobject_put(bdev->bd_holder_dir); |
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list_del_init(&holder->list); |
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kfree(holder); |
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} |
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mutex_unlock(&disk->open_mutex); |
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} |
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EXPORT_SYMBOL_GPL(bd_unlink_disk_holder); |
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int bd_register_pending_holders(struct gendisk *disk) |
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{ |
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struct bd_holder_disk *holder; |
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int ret; |
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mutex_lock(&disk->open_mutex); |
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list_for_each_entry(holder, &disk->slave_bdevs, list) { |
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ret = __link_disk_holder(holder->bdev, disk); |
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if (ret) |
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goto out_undo; |
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} |
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mutex_unlock(&disk->open_mutex); |
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return 0; |
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out_undo: |
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list_for_each_entry_continue_reverse(holder, &disk->slave_bdevs, list) |
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__unlink_disk_holder(holder->bdev, disk); |
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mutex_unlock(&disk->open_mutex); |
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return ret; |
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}
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