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block: look up holders by bdev 

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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4
block/genhd.c
View File

@ -1289,7 +1289,9 @@ struct gendisk *__alloc_disk_node(int minors, int node_id)
disk_to_dev(disk)->type = &disk_type;
device_initialize(disk_to_dev(disk));
inc_diskseq(disk);
#ifdef CONFIG_BLOCK_HOLDER_DEPRECATED
INIT_LIST_HEAD(&disk->slave_bdevs);
#endif
return disk;
out_destroy_part_tbl:

18
block/holder.c
View File

@ -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 @@ int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
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);

3
fs/block_dev.c
View File

@ -902,9 +902,6 @@ struct block_device *bdev_alloc(struct gendisk *disk, u8 partno)
bdev->bd_disk = disk;
bdev->bd_partno = partno;
bdev->bd_inode = inode;
#ifdef CONFIG_BLOCK_HOLDER_DEPRECATED
INIT_LIST_HEAD(&bdev->bd_holder_disks);
#endif
bdev->bd_stats = alloc_percpu(struct disk_stats);
if (!bdev->bd_stats) {
iput(inode);

3
include/linux/blk_types.h
View File

@ -34,9 +34,6 @@ struct block_device {
void * bd_holder;
int bd_holders;
bool bd_write_holder;
#ifdef CONFIG_BLOCK_HOLDER_DEPRECATED
struct list_head bd_holder_disks;
#endif
struct kobject *bd_holder_dir;
u8 bd_partno;
spinlock_t bd_size_lock; /* for bd_inode->i_size updates */

4
include/linux/genhd.h
View File

@ -159,7 +159,9 @@ struct gendisk {
unsigned open_partitions; /* number of open partitions */
struct kobject *slave_dir;
#ifdef CONFIG_BLOCK_HOLDER_DEPRECATED
struct list_head slave_bdevs;
#endif
struct timer_rand_state *random;
atomic_t sync_io; /* RAID */
struct disk_events *ev;