Re: [PATCH v4 5/5] block: add __must_check attribute to sb_min_blocksize()

["Darrick J. Wong" <djwong@kernel.org>]

On Tue, Nov 04, 2025 at 12:36:18AM +0800, Yongpeng Yang wrote:
> From: Yongpeng Yang <yangyongpeng@xiaomi.com>
> 
> When sb_min_blocksize() returns 0 and the return value is not checked,
> it may lead to a situation where sb->s_blocksize is 0 when
> accessing the filesystem super block. After commit a64e5a596067bd
> ("bdev: add back PAGE_SIZE block size validation for
> sb_set_blocksize()"), this becomes more likely to happen when the
> block device’s logical_block_size is larger than PAGE_SIZE and the
> filesystem is unformatted. Add the __must_check attribute to ensure
> callers always check the return value.
> 
> Suggested-by: Matthew Wilcox <willy@infradead.org>
> Signed-off-by: Yongpeng Yang <yangyongpeng@xiaomi.com>

Looks good to me,
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

--D

> ---
>  block/bdev.c       | 2 +-
>  include/linux/fs.h | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/block/bdev.c b/block/bdev.c
> index 810707cca970..638f0cd458ae 100644
> --- a/block/bdev.c
> +++ b/block/bdev.c
> @@ -231,7 +231,7 @@ int sb_set_blocksize(struct super_block *sb, int size)
>  
>  EXPORT_SYMBOL(sb_set_blocksize);
>  
> -int sb_min_blocksize(struct super_block *sb, int size)
> +int __must_check sb_min_blocksize(struct super_block *sb, int size)
>  {
>  	int minsize = bdev_logical_block_size(sb->s_bdev);
>  	if (size < minsize)
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index c895146c1444..26d4ca0f859a 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -3424,7 +3424,7 @@ extern void inode_sb_list_add(struct inode *inode);
>  extern void inode_add_lru(struct inode *inode);
>  
>  extern int sb_set_blocksize(struct super_block *, int);
> -extern int sb_min_blocksize(struct super_block *, int);
> +extern int __must_check sb_min_blocksize(struct super_block *, int);
>  
>  int generic_file_mmap(struct file *, struct vm_area_struct *);
>  int generic_file_mmap_prepare(struct vm_area_desc *desc);
> -- 
> 2.43.0
> 
>