Re: [PATCH] zonefs: move super block reading from page to folio

[Bill O'Donnell <bodonnel@redhat.com>]

On Tue, May 14, 2024 at 05:22:08PM +0200, Johannes Thumshirn wrote:
> From: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> 
> Move reading of the on-disk superblock from page to kmalloc()ed memory.
> 
> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>

Looks fine.
Reviewed-by: Bill O'Donnell <bodonnel@redhat.com>


> ---
>  fs/zonefs/super.c | 30 +++++++++++++++---------------
>  1 file changed, 15 insertions(+), 15 deletions(-)
> 
> diff --git a/fs/zonefs/super.c b/fs/zonefs/super.c
> index faf1eb87895d..ebea18da6759 100644
> --- a/fs/zonefs/super.c
> +++ b/fs/zonefs/super.c
> @@ -1111,28 +1111,28 @@ static int zonefs_read_super(struct super_block *sb)
>  	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
>  	struct zonefs_super *super;
>  	u32 crc, stored_crc;
> -	struct page *page;
>  	struct bio_vec bio_vec;
>  	struct bio bio;
> +	struct folio *folio;
>  	int ret;
>  
> -	page = alloc_page(GFP_KERNEL);
> -	if (!page)
> +	super = kzalloc(ZONEFS_SUPER_SIZE, GFP_KERNEL);
> +	if (!super)
>  		return -ENOMEM;
>  
> +	folio = virt_to_folio(super);
>  	bio_init(&bio, sb->s_bdev, &bio_vec, 1, REQ_OP_READ);
>  	bio.bi_iter.bi_sector = 0;
> -	__bio_add_page(&bio, page, PAGE_SIZE, 0);
> +	bio_add_folio_nofail(&bio, folio, ZONEFS_SUPER_SIZE,
> +			     offset_in_folio(folio, super));
>  
>  	ret = submit_bio_wait(&bio);
>  	if (ret)
> -		goto free_page;
> -
> -	super = page_address(page);
> +		goto free_super;
>  
>  	ret = -EINVAL;
>  	if (le32_to_cpu(super->s_magic) != ZONEFS_MAGIC)
> -		goto free_page;
> +		goto free_super;
>  
>  	stored_crc = le32_to_cpu(super->s_crc);
>  	super->s_crc = 0;
> @@ -1140,14 +1140,14 @@ static int zonefs_read_super(struct super_block *sb)
>  	if (crc != stored_crc) {
>  		zonefs_err(sb, "Invalid checksum (Expected 0x%08x, got 0x%08x)",
>  			   crc, stored_crc);
> -		goto free_page;
> +		goto free_super;
>  	}
>  
>  	sbi->s_features = le64_to_cpu(super->s_features);
>  	if (sbi->s_features & ~ZONEFS_F_DEFINED_FEATURES) {
>  		zonefs_err(sb, "Unknown features set 0x%llx\n",
>  			   sbi->s_features);
> -		goto free_page;
> +		goto free_super;
>  	}
>  
>  	if (sbi->s_features & ZONEFS_F_UID) {
> @@ -1155,7 +1155,7 @@ static int zonefs_read_super(struct super_block *sb)
>  				       le32_to_cpu(super->s_uid));
>  		if (!uid_valid(sbi->s_uid)) {
>  			zonefs_err(sb, "Invalid UID feature\n");
> -			goto free_page;
> +			goto free_super;
>  		}
>  	}
>  
> @@ -1164,7 +1164,7 @@ static int zonefs_read_super(struct super_block *sb)
>  				       le32_to_cpu(super->s_gid));
>  		if (!gid_valid(sbi->s_gid)) {
>  			zonefs_err(sb, "Invalid GID feature\n");
> -			goto free_page;
> +			goto free_super;
>  		}
>  	}
>  
> @@ -1173,14 +1173,14 @@ static int zonefs_read_super(struct super_block *sb)
>  
>  	if (memchr_inv(super->s_reserved, 0, sizeof(super->s_reserved))) {
>  		zonefs_err(sb, "Reserved area is being used\n");
> -		goto free_page;
> +		goto free_super;
>  	}
>  
>  	import_uuid(&sbi->s_uuid, super->s_uuid);
>  	ret = 0;
>  
> -free_page:
> -	__free_page(page);
> +free_super:
> +	kfree(super);
>  
>  	return ret;
>  }
> -- 
> 2.35.3
> 
>