[PATCH 1/2] fs: export sget_dev()

[Jan Kara]

On Wed 30-08-23 12:02:47, Christian Brauner wrote:
> > Yeah, good point. Done.
> 
> From fe40c7fe1a87814f92f9b1d0b9fb78ac69404c33 Mon Sep 17 00:00:00 2001
> From: Christian Brauner <brauner at kernel.org>
> Date: Tue, 29 Aug 2023 15:05:28 +0200
> Subject: [PATCH 1/2] fs: export sget_dev()
> 
> They will be used for mtd devices as well.
> 
> Signed-off-by: Christian Brauner <brauner at kernel.org>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack at suse.cz>

								Honza

> ---
>  fs/super.c         | 64 ++++++++++++++++++++++++++++++++--------------
>  include/linux/fs.h |  1 +
>  2 files changed, 46 insertions(+), 19 deletions(-)
> 
> diff --git a/fs/super.c b/fs/super.c
> index ad7ac3a24d38..d27d80bf7c43 100644
> --- a/fs/super.c
> +++ b/fs/super.c
> @@ -1371,6 +1371,50 @@ int get_tree_keyed(struct fs_context *fc,
>  }
>  EXPORT_SYMBOL(get_tree_keyed);
>  
> +static int set_bdev_super(struct super_block *s, void *data)
> +{
> +	s->s_dev = *(dev_t *)data;
> +	return 0;
> +}
> +
> +static int super_s_dev_set(struct super_block *s, struct fs_context *fc)
> +{
> +	return set_bdev_super(s, fc->sget_key);
> +}
> +
> +static int super_s_dev_test(struct super_block *s, struct fs_context *fc)
> +{
> +	return !(s->s_iflags & SB_I_RETIRED) &&
> +		s->s_dev == *(dev_t *)fc->sget_key;
> +}
> +
> +/**
> + * sget_dev - Find or create a superblock by device number
> + * @fc: Filesystem context.
> + * @dev: device number
> + *
> + * Find or create a superblock using the provided device number that
> + * will be stored in fc->sget_key.
> + *
> + * If an extant superblock is matched, then that will be returned with
> + * an elevated reference count that the caller must transfer or discard.
> + *
> + * If no match is made, a new superblock will be allocated and basic
> + * initialisation will be performed (s_type, s_fs_info, s_id, s_dev will
> + * be set). The superblock will be published and it will be returned in
> + * a partially constructed state with SB_BORN and SB_ACTIVE as yet
> + * unset.
> + *
> + * Return: an existing or newly created superblock on success, an error
> + *         pointer on failure.
> + */
> +struct super_block *sget_dev(struct fs_context *fc, dev_t dev)
> +{
> +	fc->sget_key = &dev;
> +	return sget_fc(fc, super_s_dev_test, super_s_dev_set);
> +}
> +EXPORT_SYMBOL(sget_dev);
> +
>  #ifdef CONFIG_BLOCK
>  /*
>   * Lock a super block that the callers holds a reference to.
> @@ -1429,23 +1473,6 @@ const struct blk_holder_ops fs_holder_ops = {
>  };
>  EXPORT_SYMBOL_GPL(fs_holder_ops);
>  
> -static int set_bdev_super(struct super_block *s, void *data)
> -{
> -	s->s_dev = *(dev_t *)data;
> -	return 0;
> -}
> -
> -static int set_bdev_super_fc(struct super_block *s, struct fs_context *fc)
> -{
> -	return set_bdev_super(s, fc->sget_key);
> -}
> -
> -static int test_bdev_super_fc(struct super_block *s, struct fs_context *fc)
> -{
> -	return !(s->s_iflags & SB_I_RETIRED) &&
> -		s->s_dev == *(dev_t *)fc->sget_key;
> -}
> -
>  int setup_bdev_super(struct super_block *sb, int sb_flags,
>  		struct fs_context *fc)
>  {
> @@ -1523,8 +1550,7 @@ int get_tree_bdev(struct fs_context *fc,
>  	}
>  
>  	fc->sb_flags |= SB_NOSEC;
> -	fc->sget_key = &dev;
> -	s = sget_fc(fc, test_bdev_super_fc, set_bdev_super_fc);
> +	s = sget_dev(fc, dev);
>  	if (IS_ERR(s))
>  		return PTR_ERR(s);
>  
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index ca8ceccde3d6..8a8d1cd5b0a9 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -2274,6 +2274,7 @@ struct super_block *sget(struct file_system_type *type,
>  			int (*test)(struct super_block *,void *),
>  			int (*set)(struct super_block *,void *),
>  			int flags, void *data);
> +struct super_block *sget_dev(struct fs_context *fc, dev_t dev);
>  
>  /* Alas, no aliases. Too much hassle with bringing module.h everywhere */
>  #define fops_get(fops) \
> -- 
> 2.34.1
> 
-- 
Jan Kara <jack at suse.com>
SUSE Labs, CR