Re: [PATCH] fs: Add uoff_t

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

On Tue, Nov 18, 2025 at 03:29:33PM +0000, Matthew Wilcox (Oracle) wrote:
> In a recent commit, I inadvertently changed a comparison from being an
> unsigned comparison (on 64-bit systems) to being a signed comparison
> (which it had always been on 32-bit systems).  This led to a sporadic
> fstests failure.
> 
> To make sure this comparison is always unsigned, introduce a new type,
> uoff_t which is the unsigned version of loff_t.  Generally file sizes
> are restricted to being a signed integer, but in these two places it is
> convenient to pass -1 to indicate "up to the end of the file".

Soo... truncate_inode_pages passes 16EB as the lend parameter to
truncate_inode_pages_range now?  I suppose that makes sense, though the
casting to loff_t by that caller no longer does...

--D

> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> ---
>  include/linux/mm.h                     | 8 ++++----
>  include/linux/shmem_fs.h               | 2 +-
>  include/linux/types.h                  | 1 +
>  include/uapi/asm-generic/posix_types.h | 1 +
>  mm/shmem.c                             | 4 ++--
>  mm/truncate.c                          | 2 +-
>  6 files changed, 10 insertions(+), 8 deletions(-)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index fe995cc3ba5c..a69ab017c370 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -3650,10 +3650,10 @@ struct vm_unmapped_area_info {
>  extern unsigned long vm_unmapped_area(struct vm_unmapped_area_info *info);
>  
>  /* truncate.c */
> -extern void truncate_inode_pages(struct address_space *, loff_t);
> -extern void truncate_inode_pages_range(struct address_space *,
> -				       loff_t lstart, loff_t lend);
> -extern void truncate_inode_pages_final(struct address_space *);
> +void truncate_inode_pages(struct address_space *mapping, loff_t lstart);
> +void truncate_inode_pages_range(struct address_space *mapping, loff_t lstart,
> +		uoff_t lend);
> +void truncate_inode_pages_final(struct address_space *mapping);
>  
>  /* generic vm_area_ops exported for stackable file systems */
>  extern vm_fault_t filemap_fault(struct vm_fault *vmf);
> diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
> index 08f497673b06..94c6237acdc9 100644
> --- a/include/linux/shmem_fs.h
> +++ b/include/linux/shmem_fs.h
> @@ -126,7 +126,7 @@ struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
>  					pgoff_t index, gfp_t gfp_mask);
>  int shmem_writeout(struct folio *folio, struct swap_iocb **plug,
>  		struct list_head *folio_list);
> -void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end);
> +void shmem_truncate_range(struct inode *inode, loff_t start, uoff_t end);
>  int shmem_unuse(unsigned int type);
>  
>  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> diff --git a/include/linux/types.h b/include/linux/types.h
> index 6dfdb8e8e4c3..d4437e9c452c 100644
> --- a/include/linux/types.h
> +++ b/include/linux/types.h
> @@ -50,6 +50,7 @@ typedef __kernel_old_gid_t	old_gid_t;
>  
>  #if defined(__GNUC__)
>  typedef __kernel_loff_t		loff_t;
> +typedef __kernel_uoff_t		uoff_t;
>  #endif
>  
>  /*
> diff --git a/include/uapi/asm-generic/posix_types.h b/include/uapi/asm-generic/posix_types.h
> index b5f7594eee7a..0a90ad92dbf3 100644
> --- a/include/uapi/asm-generic/posix_types.h
> +++ b/include/uapi/asm-generic/posix_types.h
> @@ -86,6 +86,7 @@ typedef struct {
>   */
>  typedef __kernel_long_t	__kernel_off_t;
>  typedef long long	__kernel_loff_t;
> +typedef unsigned long long	__kernel_uoff_t;
>  typedef __kernel_long_t	__kernel_old_time_t;
>  #ifndef __KERNEL__
>  typedef __kernel_long_t	__kernel_time_t;
> diff --git a/mm/shmem.c b/mm/shmem.c
> index 0a25ee095b86..728f2e04911e 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -1105,7 +1105,7 @@ static struct folio *shmem_get_partial_folio(struct inode *inode, pgoff_t index)
>   * Remove range of pages and swap entries from page cache, and free them.
>   * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate.
>   */
> -static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
> +static void shmem_undo_range(struct inode *inode, loff_t lstart, uoff_t lend,
>  								 bool unfalloc)
>  {
>  	struct address_space *mapping = inode->i_mapping;
> @@ -1256,7 +1256,7 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
>  	shmem_recalc_inode(inode, 0, -nr_swaps_freed);
>  }
>  
> -void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
> +void shmem_truncate_range(struct inode *inode, loff_t lstart, uoff_t lend)
>  {
>  	shmem_undo_range(inode, lstart, lend, false);
>  	inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));
> diff --git a/mm/truncate.c b/mm/truncate.c
> index d08340afc768..12467c1bd711 100644
> --- a/mm/truncate.c
> +++ b/mm/truncate.c
> @@ -364,7 +364,7 @@ long mapping_evict_folio(struct address_space *mapping, struct folio *folio)
>   * page aligned properly.
>   */
>  void truncate_inode_pages_range(struct address_space *mapping,
> -				loff_t lstart, loff_t lend)
> +				loff_t lstart, uoff_t lend)
>  {
>  	pgoff_t		start;		/* inclusive */
>  	pgoff_t		end;		/* exclusive */
> -- 
> 2.47.2
> 
>