Re: [PATCH 01/15] shmem: move the shmem_mapping assert into shmem_get_folio_gfp

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

On Wed, Jan 03, 2024 at 08:41:12AM +0000, Christoph Hellwig wrote:
> Move the check that the inode really is a shmemfs one from
> shmem_read_folio_gfp to shmem_get_folio_gfp given that shmem_get_folio
> can also be called from outside of shmem.c.  Also turn it into a
> WARN_ON_ONCE and error return instead of BUG_ON to be less severe.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

No complaints from me about converting a BUGON to an error return...
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> ---
>  mm/shmem.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/shmem.c b/mm/shmem.c
> index 91e2620148b2f6..3349df6d4e0360 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -1951,6 +1951,9 @@ static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
>  	int error;
>  	bool alloced;
>  
> +	if (WARN_ON_ONCE(!shmem_mapping(inode->i_mapping)))
> +		return -EINVAL;
> +
>  	if (index > (MAX_LFS_FILESIZE >> PAGE_SHIFT))
>  		return -EFBIG;
>  repeat:
> @@ -4895,7 +4898,6 @@ struct folio *shmem_read_folio_gfp(struct address_space *mapping,
>  	struct folio *folio;
>  	int error;
>  
> -	BUG_ON(!shmem_mapping(mapping));
>  	error = shmem_get_folio_gfp(inode, index, &folio, SGP_CACHE,
>  				    gfp, NULL, NULL);
>  	if (error)
> -- 
> 2.39.2
> 
>