linux-kernel - Re: [PATCH 07/25] ubifs: Store read superblock node

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Date:   Mon, 27 Aug 2018 14:50:42 +0200
From:   Richard Weinberger <richard@....at>
To:     Sascha Hauer <s.hauer@...gutronix.de>
Cc:     linux-mtd@...ts.infradead.org, David Gstir <david@...ma-star.at>,
        kernel@...gutronix.de, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 07/25] ubifs: Store read superblock node

Am Mittwoch, 4. Juli 2018, 14:41:19 CEST schrieb Sascha Hauer:
> The superblock node is read/modified/written several times throughout
> the UBIFS code. Instead of reading it from the device each time just
> keep a copy in memory and write back the modified copy when necessary.
> This patch helps for authentication support, here we not only have to
> read the superblock node, but also have to authenticate it, which
> is easier if we do it once during initialization.
> 
> Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>
> ---
>  fs/ubifs/sb.c    | 19 +++++--------------
>  fs/ubifs/super.c |  8 +-------
>  fs/ubifs/ubifs.h |  3 ++-
>  3 files changed, 8 insertions(+), 22 deletions(-)
> 
> diff --git a/fs/ubifs/sb.c b/fs/ubifs/sb.c
> index a32408f2f5c3..2fabd441d74a 100644
> --- a/fs/ubifs/sb.c
> +++ b/fs/ubifs/sb.c
> @@ -497,7 +497,7 @@ static int validate_sb(struct ubifs_info *c, struct ubifs_sb_node *sup)
>   * code. Note, the user of this function is responsible of kfree()'ing the
>   * returned superblock buffer.
>   */
> -struct ubifs_sb_node *ubifs_read_sb_node(struct ubifs_info *c)
> +static struct ubifs_sb_node *ubifs_read_sb_node(struct ubifs_info *c)
>  {
>  	struct ubifs_sb_node *sup;
>  	int err;
> @@ -554,6 +554,8 @@ int ubifs_read_superblock(struct ubifs_info *c)
>  	if (IS_ERR(sup))
>  		return PTR_ERR(sup);
>  
> +	c->superblock = sup;
> +
>  	c->fmt_version = le32_to_cpu(sup->fmt_version);
>  	c->ro_compat_version = le32_to_cpu(sup->ro_compat_version);
>  
> @@ -685,7 +687,6 @@ int ubifs_read_superblock(struct ubifs_info *c)
>  
>  	err = validate_sb(c, sup);
>  out:
> -	kfree(sup);
>  	return err;
>  }
>  
> @@ -814,7 +815,7 @@ static int fixup_free_space(struct ubifs_info *c)
>  int ubifs_fixup_free_space(struct ubifs_info *c)
>  {
>  	int err;
> -	struct ubifs_sb_node *sup;
> +	struct ubifs_sb_node *sup = c->superblock;
>  
>  	ubifs_assert(c->space_fixup);
>  	ubifs_assert(!c->ro_mount);
> @@ -825,16 +826,11 @@ int ubifs_fixup_free_space(struct ubifs_info *c)
>  	if (err)
>  		return err;
>  
> -	sup = ubifs_read_sb_node(c);
> -	if (IS_ERR(sup))
> -		return PTR_ERR(sup);
> -
>  	/* Free-space fixup is no longer required */
>  	c->space_fixup = 0;
>  	sup->flags &= cpu_to_le32(~UBIFS_FLG_SPACE_FIXUP);
>  
>  	err = ubifs_write_sb_node(c, sup);
> -	kfree(sup);
>  	if (err)
>  		return err;
>  
> @@ -845,7 +841,7 @@ int ubifs_fixup_free_space(struct ubifs_info *c)
>  int ubifs_enable_encryption(struct ubifs_info *c)
>  {
>  	int err;
> -	struct ubifs_sb_node *sup;
> +	struct ubifs_sb_node *sup = c->superblock;
>  
>  	if (c->encrypted)
>  		return 0;
> @@ -858,16 +854,11 @@ int ubifs_enable_encryption(struct ubifs_info *c)
>  		return -EINVAL;
>  	}
>  
> -	sup = ubifs_read_sb_node(c);
> -	if (IS_ERR(sup))
> -		return PTR_ERR(sup);
> -
>  	sup->flags |= cpu_to_le32(UBIFS_FLG_ENCRYPTION);
>  
>  	err = ubifs_write_sb_node(c, sup);
>  	if (!err)
>  		c->encrypted = 1;
> -	kfree(sup);
>  
>  	return err;
>  }
> diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
> index c5466c70d620..9e44baec30a3 100644
> --- a/fs/ubifs/super.c
> +++ b/fs/ubifs/super.c
> @@ -1580,16 +1580,10 @@ static int ubifs_remount_rw(struct ubifs_info *c)
>  		goto out;
>  
>  	if (c->old_leb_cnt != c->leb_cnt) {
> -		struct ubifs_sb_node *sup;
> +		struct ubifs_sb_node *sup = c->superblock;
>  
> -		sup = ubifs_read_sb_node(c);
> -		if (IS_ERR(sup)) {
> -			err = PTR_ERR(sup);
> -			goto out;
> -		}
>  		sup->leb_cnt = cpu_to_le32(c->leb_cnt);
>  		err = ubifs_write_sb_node(c, sup);
> -		kfree(sup);
>  		if (err)
>  			goto out;
>  	}
> diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
> index 83c5e75ed3b6..92574045e030 100644
> --- a/fs/ubifs/ubifs.h
> +++ b/fs/ubifs/ubifs.h
> @@ -971,6 +971,7 @@ struct ubifs_debug_info;
>   * struct ubifs_info - UBIFS file-system description data structure
>   * (per-superblock).
>   * @vfs_sb: VFS @struct super_block object
> + * @superblock: The super block node as read from the device

Please name it sup_node to have consistent naming scheme.
We already store the master node, @mst_node.

Thanks,
//richard