-#ifdef CONFIG_SYSFS
-/*
- * Functions for bd_claim_by_kobject / bd_release_from_kobject
- *
- * If a kobject is passed to bd_claim_by_kobject()
- * and the kobject has a parent directory,
- * following symlinks are created:
- * o from the kobject to the claimed bdev
- * o from "holders" directory of the bdev to the parent of the kobject
- * bd_release_from_kobject() removes these symlinks.
- *
- * Example:
- * If /dev/dm-0 maps to /dev/sda, kobject corresponding to
- * /sys/block/dm-0/slaves is passed to bd_claim_by_kobject(), then:
- * /sys/block/dm-0/slaves/sda --> /sys/block/sda
- * /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
- */
-
-static struct kobject *bdev_get_kobj(struct block_device *bdev)
-{
- if (bdev->bd_contains != bdev)
- return kobject_get(&bdev->bd_part->kobj);
- else
- return kobject_get(&bdev->bd_disk->kobj);
-}
-
-static struct kobject *bdev_get_holder(struct block_device *bdev)
-{
- if (bdev->bd_contains != bdev)
- return kobject_get(bdev->bd_part->holder_dir);
- else
- return kobject_get(bdev->bd_disk->holder_dir);
-}
-
-static void add_symlink(struct kobject *from, struct kobject *to)
-{
- if (!from || !to)
- return;
- sysfs_create_link(from, to, kobject_name(to));
-}
-
-static void del_symlink(struct kobject *from, struct kobject *to)
-{
- if (!from || !to)
- return;
- sysfs_remove_link(from, kobject_name(to));
-}
-
-/*
- * 'struct bd_holder' contains pointers to kobjects symlinked by
- * bd_claim_by_kobject.
- * It's connected to bd_holder_list which is protected by bdev->bd_sem.
- */
-struct bd_holder {
- struct list_head list; /* chain of holders of the bdev */
- int count; /* references from the holder */
- struct kobject *sdir; /* holder object, e.g. "/block/dm-0/slaves" */
- struct kobject *hdev; /* e.g. "/block/dm-0" */
- struct kobject *hdir; /* e.g. "/block/sda/holders" */
- struct kobject *sdev; /* e.g. "/block/sda" */
-};
-
-/*
- * Get references of related kobjects at once.
- * Returns 1 on success. 0 on failure.
- *
- * Should call bd_holder_release_dirs() after successful use.
- */
-static int bd_holder_grab_dirs(struct block_device *bdev,
- struct bd_holder *bo)
-{
- if (!bdev || !bo)
- return 0;
-
- bo->sdir = kobject_get(bo->sdir);
- if (!bo->sdir)
- return 0;
-
- bo->hdev = kobject_get(bo->sdir->parent);
- if (!bo->hdev)
- goto fail_put_sdir;
-
- bo->sdev = bdev_get_kobj(bdev);
- if (!bo->sdev)
- goto fail_put_hdev;
-
- bo->hdir = bdev_get_holder(bdev);
- if (!bo->hdir)
- goto fail_put_sdev;
-
- return 1;
-
-fail_put_sdev:
- kobject_put(bo->sdev);
-fail_put_hdev:
- kobject_put(bo->hdev);
-fail_put_sdir:
- kobject_put(bo->sdir);
-
- return 0;
-}
-
-/* Put references of related kobjects at once. */
-static void bd_holder_release_dirs(struct bd_holder *bo)
-{
- kobject_put(bo->hdir);
- kobject_put(bo->sdev);
- kobject_put(bo->hdev);
- kobject_put(bo->sdir);
-}
-
-static struct bd_holder *alloc_bd_holder(struct kobject *kobj)
-{
- struct bd_holder *bo;
-
- bo = kzalloc(sizeof(*bo), GFP_KERNEL);
- if (!bo)
- return NULL;
-
- bo->count = 1;
- bo->sdir = kobj;
-
- return bo;
-}
-
-static void free_bd_holder(struct bd_holder *bo)
-{
- kfree(bo);
-}
-
-/**
- * add_bd_holder - create sysfs symlinks for bd_claim() relationship
- *
- * @bdev: block device to be bd_claimed
- * @bo: preallocated and initialized by alloc_bd_holder()
- *
- * If there is no matching entry with @bo in @bdev->bd_holder_list,
- * add @bo to the list, create symlinks.
- *
- * Returns 1 if @bo was added to the list.
- * Returns 0 if @bo wasn't used by any reason and should be freed.
- */
-static int add_bd_holder(struct block_device *bdev, struct bd_holder *bo)
-{
- struct bd_holder *tmp;
-
- if (!bo)
- return 0;
-
- list_for_each_entry(tmp, &bdev->bd_holder_list, list) {
- if (tmp->sdir == bo->sdir) {
- tmp->count++;
- return 0;
- }
- }
-
- if (!bd_holder_grab_dirs(bdev, bo))
- return 0;
-
- add_symlink(bo->sdir, bo->sdev);
- add_symlink(bo->hdir, bo->hdev);
- list_add_tail(&bo->list, &bdev->bd_holder_list);
- return 1;
-}
-
-/**
- * del_bd_holder - delete sysfs symlinks for bd_claim() relationship
- *
- * @bdev: block device to be bd_claimed
- * @kobj: holder's kobject
- *
- * If there is matching entry with @kobj in @bdev->bd_holder_list
- * and no other bd_claim() from the same kobject,
- * remove the struct bd_holder from the list, delete symlinks for it.
- *
- * Returns a pointer to the struct bd_holder when it's removed from the list
- * and ready to be freed.
- * Returns NULL if matching claim isn't found or there is other bd_claim()
- * by the same kobject.
- */
-static struct bd_holder *del_bd_holder(struct block_device *bdev,
- struct kobject *kobj)
-{
- struct bd_holder *bo;
-
- list_for_each_entry(bo, &bdev->bd_holder_list, list) {
- if (bo->sdir == kobj) {
- bo->count--;
- BUG_ON(bo->count < 0);
- if (!bo->count) {
- list_del(&bo->list);
- del_symlink(bo->sdir, bo->sdev);
- del_symlink(bo->hdir, bo->hdev);
- bd_holder_release_dirs(bo);
- return bo;
- }
- break;
- }
- }
-
- return NULL;
-}
-
-/**
- * bd_claim_by_kobject - bd_claim() with additional kobject signature
- *
- * @bdev: block device to be claimed
- * @holder: holder's signature
- * @kobj: holder's kobject
- *
- * Do bd_claim() and if it succeeds, create sysfs symlinks between
- * the bdev and the holder's kobject.
- * Use bd_release_from_kobject() when relesing the claimed bdev.
- *
- * Returns 0 on success. (same as bd_claim())
- * Returns errno on failure.
- */
-static int bd_claim_by_kobject(struct block_device *bdev, void *holder,
- struct kobject *kobj)
-{
- int res;
- struct bd_holder *bo;
-
- if (!kobj)
- return -EINVAL;
-
- bo = alloc_bd_holder(kobj);
- if (!bo)
- return -ENOMEM;
-
- mutex_lock(&bdev->bd_mutex);
- res = bd_claim(bdev, holder);
- if (res || !add_bd_holder(bdev, bo))
- free_bd_holder(bo);
- mutex_unlock(&bdev->bd_mutex);
-
- return res;
-}
-
-/**
- * bd_release_from_kobject - bd_release() with additional kobject signature
- *
- * @bdev: block device to be released
- * @kobj: holder's kobject
- *
- * Do bd_release() and remove sysfs symlinks created by bd_claim_by_kobject().
- */
-static void bd_release_from_kobject(struct block_device *bdev,
- struct kobject *kobj)
-{
- struct bd_holder *bo;
-
- if (!kobj)
- return;
-
- mutex_lock(&bdev->bd_mutex);
- bd_release(bdev);
- if ((bo = del_bd_holder(bdev, kobj)))
- free_bd_holder(bo);
- mutex_unlock(&bdev->bd_mutex);
-}
-
-/**
- * bd_claim_by_disk - wrapper function for bd_claim_by_kobject()
- *
- * @bdev: block device to be claimed
- * @holder: holder's signature
- * @disk: holder's gendisk
- *
- * Call bd_claim_by_kobject() with getting @disk->slave_dir.
- */
-int bd_claim_by_disk(struct block_device *bdev, void *holder,
- struct gendisk *disk)
-{
- return bd_claim_by_kobject(bdev, holder, kobject_get(disk->slave_dir));
-}
-EXPORT_SYMBOL_GPL(bd_claim_by_disk);
-
-/**
- * bd_release_from_disk - wrapper function for bd_release_from_kobject()
- *
- * @bdev: block device to be claimed
- * @disk: holder's gendisk
- *
- * Call bd_release_from_kobject() and put @disk->slave_dir.
- */
-void bd_release_from_disk(struct block_device *bdev, struct gendisk *disk)
-{
- bd_release_from_kobject(bdev, disk->slave_dir);
- kobject_put(disk->slave_dir);
-}
-EXPORT_SYMBOL_GPL(bd_release_from_disk);
-#endif
-