forked from Minki/linux
block: simplify holder symlink handling
Code to manage symlinks in /sys/block/*/{holders|slaves} are overly
complex with multiple holder considerations, redundant extra
references to all involved kobjects, unused generic kobject holder
support and unnecessary mixup with bd_claim/release functionalities.
Strip it down to what's necessary (single gendisk holder) and make it
use a separate interface. This is a step for cleaning up
bd_claim/release. This patch makes dm-table slightly more complex but
it will be simplified again with further changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Neil Brown <neilb@suse.de>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Cc: dm-devel@redhat.com
This commit is contained in:
Tejun Heo
parent
37004c42f7
commit
e09b457bdb
@ -328,12 +328,22 @@ static int open_dev(struct dm_dev_internal *d, dev_t dev,
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bdev = open_by_devnum(dev, d->dm_dev.mode);
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if (IS_ERR(bdev))
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return PTR_ERR(bdev);
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r = bd_claim_by_disk(bdev, _claim_ptr, dm_disk(md));
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if (r)
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r = bd_claim(bdev, _claim_ptr);
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if (r) {
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blkdev_put(bdev, d->dm_dev.mode);
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else
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d->dm_dev.bdev = bdev;
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return r;
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return r;
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}
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r = bd_link_disk_holder(bdev, dm_disk(md));
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if (r) {
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bd_release(bdev);
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blkdev_put(bdev, d->dm_dev.mode);
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return r;
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}
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d->dm_dev.bdev = bdev;
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return 0;
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}
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/*
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@ -344,7 +354,8 @@ static void close_dev(struct dm_dev_internal *d, struct mapped_device *md)
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if (!d->dm_dev.bdev)
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return;
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bd_release_from_disk(d->dm_dev.bdev, dm_disk(md));
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bd_unlink_disk_holder(d->dm_dev.bdev);
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bd_release(d->dm_dev.bdev);
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blkdev_put(d->dm_dev.bdev, d->dm_dev.mode);
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d->dm_dev.bdev = NULL;
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}
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@ -1880,7 +1880,7 @@ static int bind_rdev_to_array(mdk_rdev_t * rdev, mddev_t * mddev)
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rdev->sysfs_state = sysfs_get_dirent_safe(rdev->kobj.sd, "state");
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list_add_rcu(&rdev->same_set, &mddev->disks);
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bd_claim_by_disk(rdev->bdev, rdev->bdev->bd_holder, mddev->gendisk);
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bd_link_disk_holder(rdev->bdev, mddev->gendisk);
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/* May as well allow recovery to be retried once */
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mddev->recovery_disabled = 0;
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@ -1907,7 +1907,7 @@ static void unbind_rdev_from_array(mdk_rdev_t * rdev)
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MD_BUG();
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return;
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}
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bd_release_from_disk(rdev->bdev, rdev->mddev->gendisk);
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bd_unlink_disk_holder(rdev->bdev);
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list_del_rcu(&rdev->same_set);
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printk(KERN_INFO "md: unbind<%s>\n", bdevname(rdev->bdev,b));
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rdev->mddev = NULL;
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334
fs/block_dev.c
334
fs/block_dev.c
@ -426,9 +426,6 @@ static void init_once(void *foo)
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mutex_init(&bdev->bd_mutex);
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INIT_LIST_HEAD(&bdev->bd_inodes);
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INIT_LIST_HEAD(&bdev->bd_list);
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#ifdef CONFIG_SYSFS
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INIT_LIST_HEAD(&bdev->bd_holder_list);
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#endif
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inode_init_once(&ei->vfs_inode);
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/* Initialize mutex for freeze. */
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mutex_init(&bdev->bd_fsfreeze_mutex);
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@ -881,314 +878,83 @@ void bd_release(struct block_device *bdev)
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EXPORT_SYMBOL(bd_release);
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#ifdef CONFIG_SYSFS
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/*
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* Functions for bd_claim_by_kobject / bd_release_from_kobject
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*
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* If a kobject is passed to bd_claim_by_kobject()
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* and the kobject has a parent directory,
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* following symlinks are created:
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* o from the kobject to the claimed bdev
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* o from "holders" directory of the bdev to the parent of the kobject
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* bd_release_from_kobject() removes these symlinks.
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*
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* Example:
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* If /dev/dm-0 maps to /dev/sda, kobject corresponding to
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* /sys/block/dm-0/slaves is passed to bd_claim_by_kobject(), then:
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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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static int add_symlink(struct kobject *from, struct kobject *to)
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{
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if (!from || !to)
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return 0;
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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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if (!from || !to)
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return;
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sysfs_remove_link(from, kobject_name(to));
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}
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/*
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* 'struct bd_holder' contains pointers to kobjects symlinked by
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* bd_claim_by_kobject.
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* It's connected to bd_holder_list which is protected by bdev->bd_sem.
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*/
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struct bd_holder {
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struct list_head list; /* chain of holders of the bdev */
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int count; /* references from the holder */
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struct kobject *sdir; /* holder object, e.g. "/block/dm-0/slaves" */
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struct kobject *hdev; /* e.g. "/block/dm-0" */
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struct kobject *hdir; /* e.g. "/block/sda/holders" */
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struct kobject *sdev; /* e.g. "/block/sda" */
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};
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/*
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* Get references of related kobjects at once.
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* Returns 1 on success. 0 on failure.
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*
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* Should call bd_holder_release_dirs() after successful use.
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*/
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static int bd_holder_grab_dirs(struct block_device *bdev,
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struct bd_holder *bo)
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{
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if (!bdev || !bo)
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return 0;
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bo->sdir = kobject_get(bo->sdir);
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if (!bo->sdir)
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return 0;
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bo->hdev = kobject_get(bo->sdir->parent);
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if (!bo->hdev)
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goto fail_put_sdir;
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bo->sdev = kobject_get(&part_to_dev(bdev->bd_part)->kobj);
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if (!bo->sdev)
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goto fail_put_hdev;
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bo->hdir = kobject_get(bdev->bd_part->holder_dir);
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if (!bo->hdir)
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goto fail_put_sdev;
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return 1;
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fail_put_sdev:
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kobject_put(bo->sdev);
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fail_put_hdev:
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kobject_put(bo->hdev);
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fail_put_sdir:
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kobject_put(bo->sdir);
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return 0;
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}
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/* Put references of related kobjects at once. */
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static void bd_holder_release_dirs(struct bd_holder *bo)
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{
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kobject_put(bo->hdir);
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kobject_put(bo->sdev);
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kobject_put(bo->hdev);
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kobject_put(bo->sdir);
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}
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static struct bd_holder *alloc_bd_holder(struct kobject *kobj)
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{
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struct bd_holder *bo;
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bo = kzalloc(sizeof(*bo), GFP_KERNEL);
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if (!bo)
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return NULL;
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bo->count = 1;
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bo->sdir = kobj;
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return bo;
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}
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static void free_bd_holder(struct bd_holder *bo)
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{
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kfree(bo);
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}
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/**
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* find_bd_holder - find matching struct bd_holder from the block device
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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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* @bdev: struct block device to be searched
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* @bo: target struct bd_holder
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* This functions creates the following sysfs symlinks.
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*
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* Returns matching entry with @bo in @bdev->bd_holder_list.
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* If found, increment the reference count and return the pointer.
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* If not found, returns NULL.
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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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static struct bd_holder *find_bd_holder(struct block_device *bdev,
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struct bd_holder *bo)
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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 *tmp;
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list_for_each_entry(tmp, &bdev->bd_holder_list, list)
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if (tmp->sdir == bo->sdir) {
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tmp->count++;
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return tmp;
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}
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return NULL;
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}
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/**
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* add_bd_holder - create sysfs symlinks for bd_claim() relationship
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*
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* @bdev: block device to be bd_claimed
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* @bo: preallocated and initialized by alloc_bd_holder()
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*
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* Add @bo to @bdev->bd_holder_list, create symlinks.
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*
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* Returns 0 if symlinks are created.
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* Returns -ve if something fails.
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*/
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static int add_bd_holder(struct block_device *bdev, struct bd_holder *bo)
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{
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int err;
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if (!bo)
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return -EINVAL;
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if (!bd_holder_grab_dirs(bdev, bo))
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return -EBUSY;
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err = add_symlink(bo->sdir, bo->sdev);
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if (err)
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return err;
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err = add_symlink(bo->hdir, bo->hdev);
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if (err) {
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del_symlink(bo->sdir, bo->sdev);
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return err;
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}
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list_add_tail(&bo->list, &bdev->bd_holder_list);
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return 0;
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}
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/**
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* del_bd_holder - delete sysfs symlinks for bd_claim() relationship
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*
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* @bdev: block device to be bd_claimed
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* @kobj: holder's kobject
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*
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* If there is matching entry with @kobj in @bdev->bd_holder_list
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* and no other bd_claim() from the same kobject,
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* remove the struct bd_holder from the list, delete symlinks for it.
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*
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* Returns a pointer to the struct bd_holder when it's removed from the list
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* and ready to be freed.
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* Returns NULL if matching claim isn't found or there is other bd_claim()
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* by the same kobject.
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*/
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static struct bd_holder *del_bd_holder(struct block_device *bdev,
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struct kobject *kobj)
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{
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struct bd_holder *bo;
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list_for_each_entry(bo, &bdev->bd_holder_list, list) {
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if (bo->sdir == kobj) {
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bo->count--;
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BUG_ON(bo->count < 0);
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if (!bo->count) {
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list_del(&bo->list);
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del_symlink(bo->sdir, bo->sdev);
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del_symlink(bo->hdir, bo->hdev);
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bd_holder_release_dirs(bo);
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return bo;
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}
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break;
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}
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}
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return NULL;
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}
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/**
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* bd_claim_by_kobject - bd_claim() with additional kobject signature
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*
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* @bdev: block device to be claimed
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* @holder: holder's signature
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* @kobj: holder's kobject
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*
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* Do bd_claim() and if it succeeds, create sysfs symlinks between
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* the bdev and the holder's kobject.
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* Use bd_release_from_kobject() when relesing the claimed bdev.
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*
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* Returns 0 on success. (same as bd_claim())
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* Returns errno on failure.
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*/
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static int bd_claim_by_kobject(struct block_device *bdev, void *holder,
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struct kobject *kobj)
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{
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int err;
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struct bd_holder *bo, *found;
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if (!kobj)
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return -EINVAL;
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bo = alloc_bd_holder(kobj);
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if (!bo)
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return -ENOMEM;
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int ret = 0;
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mutex_lock(&bdev->bd_mutex);
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err = bd_claim(bdev, holder);
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if (err)
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goto fail;
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WARN_ON_ONCE(!bdev->bd_holder || bdev->bd_holder_disk);
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found = find_bd_holder(bdev, bo);
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if (found)
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goto fail;
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/* FIXME: remove the following once add_disk() handles errors */
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if (WARN_ON(!disk->slave_dir || !bdev->bd_part->holder_dir))
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goto out_unlock;
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err = add_bd_holder(bdev, bo);
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if (err)
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bd_release(bdev);
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else
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bo = NULL;
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fail:
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ret = add_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
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if (ret)
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goto out_unlock;
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ret = add_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj);
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if (ret) {
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del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
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goto out_unlock;
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}
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bdev->bd_holder_disk = disk;
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out_unlock:
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mutex_unlock(&bdev->bd_mutex);
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free_bd_holder(bo);
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return err;
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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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/**
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* bd_release_from_kobject - bd_release() with additional kobject signature
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*
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* @bdev: block device to be released
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* @kobj: holder's kobject
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*
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* Do bd_release() and remove sysfs symlinks created by bd_claim_by_kobject().
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*/
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static void bd_release_from_kobject(struct block_device *bdev,
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struct kobject *kobj)
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void bd_unlink_disk_holder(struct block_device *bdev)
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{
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if (!kobj)
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struct gendisk *disk = bdev->bd_holder_disk;
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bdev->bd_holder_disk = NULL;
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if (!disk)
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return;
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mutex_lock(&bdev->bd_mutex);
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bd_release(bdev);
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free_bd_holder(del_bd_holder(bdev, kobj));
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mutex_unlock(&bdev->bd_mutex);
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del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
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del_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj);
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}
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/**
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* bd_claim_by_disk - wrapper function for bd_claim_by_kobject()
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*
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* @bdev: block device to be claimed
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* @holder: holder's signature
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* @disk: holder's gendisk
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*
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* Call bd_claim_by_kobject() with getting @disk->slave_dir.
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*/
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int bd_claim_by_disk(struct block_device *bdev, void *holder,
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struct gendisk *disk)
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{
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return bd_claim_by_kobject(bdev, holder, kobject_get(disk->slave_dir));
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}
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EXPORT_SYMBOL_GPL(bd_claim_by_disk);
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/**
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* bd_release_from_disk - wrapper function for bd_release_from_kobject()
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*
|
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* @bdev: block device to be claimed
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* @disk: holder's gendisk
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*
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* Call bd_release_from_kobject() and put @disk->slave_dir.
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*/
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void bd_release_from_disk(struct block_device *bdev, struct gendisk *disk)
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{
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bd_release_from_kobject(bdev, disk->slave_dir);
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kobject_put(disk->slave_dir);
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}
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EXPORT_SYMBOL_GPL(bd_release_from_disk);
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EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
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#endif
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/*
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@ -663,7 +663,7 @@ struct block_device {
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void * bd_holder;
|
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int bd_holders;
|
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#ifdef CONFIG_SYSFS
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struct list_head bd_holder_list;
|
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struct gendisk * bd_holder_disk; /* for sysfs slave linkng */
|
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#endif
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struct block_device * bd_contains;
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unsigned bd_block_size;
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@ -2042,11 +2042,17 @@ extern int blkdev_put(struct block_device *, fmode_t);
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extern int bd_claim(struct block_device *, void *);
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extern void bd_release(struct block_device *);
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#ifdef CONFIG_SYSFS
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extern int bd_claim_by_disk(struct block_device *, void *, struct gendisk *);
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extern void bd_release_from_disk(struct block_device *, struct gendisk *);
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||||
extern int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk);
|
||||
extern void bd_unlink_disk_holder(struct block_device *bdev);
|
||||
#else
|
||||
#define bd_claim_by_disk(bdev, holder, disk) bd_claim(bdev, holder)
|
||||
#define bd_release_from_disk(bdev, disk) bd_release(bdev)
|
||||
static inline int bd_link_disk_holder(struct block_device *bdev,
|
||||
struct gendisk *disk)
|
||||
{
|
||||
return 0;
|
||||
}
|
||||
static inline void bd_unlink_disk_holder(struct block_device *bdev)
|
||||
{
|
||||
}
|
||||
#endif
|
||||
#endif
|
||||
|
||||
|
||||
Loading…
Reference in New Issue
Block a user