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block: look up holders by bdev

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Invert they way the holder relations are tracked.  This very
slightly reduces the memory overhead for partitioned devices.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210804094147.459763-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig
2021-08-04 11:41:42 +02:00
committed by Jens Axboe
parent fbd9a39542
commit 0dbcfe247f
5 changed files with 15 additions and 17 deletions
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18
block/holder.c
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@@ -3,7 +3,7 @@
struct bd_holder_disk {
struct list_head list;
struct gendisk *disk;
struct block_device *bdev;
int refcnt;
};
@@ -12,8 +12,8 @@ static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev,
{
struct bd_holder_disk *holder;
list_for_each_entry(holder, &bdev->bd_holder_disks, list)
if (holder->disk == disk)
list_for_each_entry(holder, &disk->slave_bdevs, list)
if (holder->bdev == bdev)
return holder;
return NULL;
}
@@ -61,7 +61,7 @@ int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
struct bd_holder_disk *holder;
int ret = 0;
mutex_lock(&bdev->bd_disk->open_mutex);
mutex_lock(&disk->open_mutex);
WARN_ON_ONCE(!bdev->bd_holder);
@@ -82,7 +82,7 @@ int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
}
INIT_LIST_HEAD(&holder->list);
holder->disk = disk;
holder->bdev = bdev;
holder->refcnt = 1;
ret = add_symlink(disk->slave_dir, bdev_kobj(bdev));
@@ -93,7 +93,7 @@ int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
if (ret)
goto out_del;
list_add(&holder->list, &bdev->bd_holder_disks);
list_add(&holder->list, &disk->slave_bdevs);
goto out_unlock;
out_del:
@@ -101,7 +101,7 @@ out_del:
out_free:
kfree(holder);
out_unlock:
mutex_unlock(&bdev->bd_disk->open_mutex);
mutex_unlock(&disk->open_mutex);
return ret;
}
EXPORT_SYMBOL_GPL(bd_link_disk_holder);
@@ -120,7 +120,7 @@ void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
{
struct bd_holder_disk *holder;
mutex_lock(&bdev->bd_disk->open_mutex);
mutex_lock(&disk->open_mutex);
holder = bd_find_holder_disk(bdev, disk);
if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) {
del_symlink(disk->slave_dir, bdev_kobj(bdev));
@@ -128,6 +128,6 @@ void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
list_del_init(&holder->list);
kfree(holder);
}
mutex_unlock(&bdev->bd_disk->open_mutex);
mutex_unlock(&disk->open_mutex);
}
EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);