Re: [PATCH 23/45] block: remove i_bdev

[Coly Li <colyli@xxxxxxx>]

On 11/24/20 9:27 PM, Christoph Hellwig wrote:
> Switch the block device lookup interfaces to directly work with a dev_t
> so that struct block_device references are only acquired by the
> blkdev_get variants (and the blk-cgroup special case).  This means that
> we not don't need an extra reference in the inode and can generally
> simplify handling of struct block_device to keep the lookups contained
> in the core block layer code.
> 
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>

For the bcache part, Acked-by: Coly Li <colyli@xxxxxxx>

Thanks.

Coly Li

> ---
>  block/ioctl.c                                |   3 +-
>  drivers/block/loop.c                         |   8 +-
>  drivers/md/bcache/super.c                    |  20 +-
>  drivers/md/dm-table.c                        |   9 +-
>  drivers/mtd/mtdsuper.c                       |  17 +-
>  drivers/target/target_core_file.c            |   6 +-
>  drivers/usb/gadget/function/storage_common.c |   8 +-
>  fs/block_dev.c                               | 195 +++++--------------
>  fs/btrfs/volumes.c                           |  13 +-
>  fs/inode.c                                   |   3 -
>  fs/internal.h                                |   7 +-
>  fs/io_uring.c                                |  10 +-
>  fs/pipe.c                                    |   5 +-
>  fs/quota/quota.c                             |  19 +-
>  fs/statfs.c                                  |   2 +-
>  fs/super.c                                   |  37 ++--
>  include/linux/blkdev.h                       |   2 +-
>  include/linux/fs.h                           |   1 -
>  18 files changed, 114 insertions(+), 251 deletions(-)
> 

[snipped]

> diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
> index a6a5e21e4fd136..c55d3c58a7ef55 100644
> --- a/drivers/md/bcache/super.c
> +++ b/drivers/md/bcache/super.c
> @@ -2380,38 +2380,38 @@ kobj_attribute_write(register,                
> register_bcache);
>  kobj_attribute_write(register_quiet, register_bcache);
>  kobj_attribute_write(pendings_cleanup,       bch_pending_bdevs_cleanup);
>  
> -static bool bch_is_open_backing(struct block_device *bdev)
> +static bool bch_is_open_backing(dev_t dev)
>  {
>       struct cache_set *c, *tc;
>       struct cached_dev *dc, *t;
>  
>       list_for_each_entry_safe(c, tc, &bch_cache_sets, list)
>               list_for_each_entry_safe(dc, t, &c->cached_devs, list)
> -                     if (dc->bdev == bdev)
> +                     if (dc->bdev->bd_dev == dev)
>                               return true;
>       list_for_each_entry_safe(dc, t, &uncached_devices, list)
> -             if (dc->bdev == bdev)
> +             if (dc->bdev->bd_dev == dev)
>                       return true;
>       return false;
>  }
>  
> -static bool bch_is_open_cache(struct block_device *bdev)
> +static bool bch_is_open_cache(dev_t dev)
>  {
>       struct cache_set *c, *tc;
>  
>       list_for_each_entry_safe(c, tc, &bch_cache_sets, list) {
>               struct cache *ca = c->cache;
>  
> -             if (ca->bdev == bdev)
> +             if (ca->bdev->bd_dev == dev)
>                       return true;
>       }
>  
>       return false;
>  }
>  
> -static bool bch_is_open(struct block_device *bdev)
> +static bool bch_is_open(dev_t dev)
>  {
> -     return bch_is_open_cache(bdev) || bch_is_open_backing(bdev);
> +     return bch_is_open_cache(dev) || bch_is_open_backing(dev);
>  }
>  
>  struct async_reg_args {
> @@ -2535,9 +2535,11 @@ static ssize_t register_bcache(struct kobject *k, 
> struct kobj_attribute *attr,
>                                 sb);
>       if (IS_ERR(bdev)) {
>               if (bdev == ERR_PTR(-EBUSY)) {
> -                     bdev = lookup_bdev(strim(path));
> +                     dev_t dev;
> +
>                       mutex_lock(&bch_register_lock);
> -                     if (!IS_ERR(bdev) && bch_is_open(bdev))
> +                     if (lookup_bdev(strim(path), &dev) == 0 &&
> +                         bch_is_open(dev))
>                               err = "device already registered";
>                       else
>                               err = "device busy";
[snipped]