Re: [PATCH 01/10] mm: rename call_mmap/mmap_prepare to vfs_mmap/mmap_prepare

[Vlastimil Babka]

On 6/16/25 21:33, Lorenzo Stoakes wrote:
> The call_mmap() function violates the existing convention in
> include/linux/fs.h whereby invocations of virtual file system hooks is
> performed by functions prefixed with vfs_xxx().
> 
> Correct this by renaming call_mmap() to vfs_mmap(). This also avoids
> confusion as to the fact that f_op->mmap_prepare may be invoked here.
> 
> Also rename __call_mmap_prepare() function to vfs_mmap_prepare() and adjust
> to accept a file parameter, this is useful later for nested file systems.
> 
> Finally, fix up the VMA userland tests and ensure the mmap_prepare -> mmap
> shim is implemented there.
> 
> Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>

Acked-by: Vlastimil Babka <vbabka@xxxxxxx>

> ---
>  drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c |  2 +-
>  fs/backing-file.c                          |  2 +-
>  fs/coda/file.c                             |  4 +--
>  include/linux/fs.h                         |  5 ++--
>  ipc/shm.c                                  |  2 +-
>  mm/internal.h                              |  2 +-
>  mm/vma.c                                   |  2 +-
>  tools/testing/vma/vma_internal.h           | 32 ++++++++++++++++++----
>  8 files changed, 35 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
> index 05e440643aa2..f4f1c979d1b9 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
> @@ -105,7 +105,7 @@ static int i915_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struct *
>  	if (!obj->base.filp)
>  		return -ENODEV;
>  
> -	ret = call_mmap(obj->base.filp, vma);
> +	ret = vfs_mmap(obj->base.filp, vma);
>  	if (ret)
>  		return ret;
>  
> diff --git a/fs/backing-file.c b/fs/backing-file.c
> index 763fbe9b72b2..04018679bf69 100644
> --- a/fs/backing-file.c
> +++ b/fs/backing-file.c
> @@ -339,7 +339,7 @@ int backing_file_mmap(struct file *file, struct vm_area_struct *vma,
>  	vma_set_file(vma, file);
>  
>  	old_cred = override_creds(ctx->cred);
> -	ret = call_mmap(vma->vm_file, vma);
> +	ret = vfs_mmap(vma->vm_file, vma);
>  	revert_creds(old_cred);
>  
>  	if (ctx->accessed)
> diff --git a/fs/coda/file.c b/fs/coda/file.c
> index 148856a582a9..2e6ea9319b35 100644
> --- a/fs/coda/file.c
> +++ b/fs/coda/file.c
> @@ -199,10 +199,10 @@ coda_file_mmap(struct file *coda_file, struct vm_area_struct *vma)
>  	spin_unlock(&cii->c_lock);
>  
>  	vma->vm_file = get_file(host_file);
> -	ret = call_mmap(vma->vm_file, vma);
> +	ret = vfs_mmap(vma->vm_file, vma);
>  
>  	if (ret) {
> -		/* if call_mmap fails, our caller will put host_file so we
> +		/* if vfs_mmap fails, our caller will put host_file so we
>  		 * should drop the reference to the coda_file that we got.
>  		 */
>  		fput(coda_file);
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 93ee0d2d6f1a..7120f80255b3 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -2278,7 +2278,7 @@ static inline bool file_has_valid_mmap_hooks(struct file *file)
>  
>  int compat_vma_mmap_prepare(struct file *file, struct vm_area_struct *vma);
>  
> -static inline int call_mmap(struct file *file, struct vm_area_struct *vma)
> +static inline int vfs_mmap(struct file *file, struct vm_area_struct *vma)
>  {
>  	if (file->f_op->mmap_prepare)
>  		return compat_vma_mmap_prepare(file, vma);
> @@ -2286,8 +2286,7 @@ static inline int call_mmap(struct file *file, struct vm_area_struct *vma)
>  	return file->f_op->mmap(file, vma);
>  }
>  
> -static inline int __call_mmap_prepare(struct file *file,
> -		struct vm_area_desc *desc)
> +static inline int vfs_mmap_prepare(struct file *file, struct vm_area_desc *desc)
>  {
>  	return file->f_op->mmap_prepare(desc);
>  }
> diff --git a/ipc/shm.c b/ipc/shm.c
> index 492fcc699985..a9310b6dbbc3 100644
> --- a/ipc/shm.c
> +++ b/ipc/shm.c
> @@ -602,7 +602,7 @@ static int shm_mmap(struct file *file, struct vm_area_struct *vma)
>  	if (ret)
>  		return ret;
>  
> -	ret = call_mmap(sfd->file, vma);
> +	ret = vfs_mmap(sfd->file, vma);
>  	if (ret) {
>  		__shm_close(sfd);
>  		return ret;
> diff --git a/mm/internal.h b/mm/internal.h
> index 3823fb356d3b..a55c88afff6d 100644
> --- a/mm/internal.h
> +++ b/mm/internal.h
> @@ -165,7 +165,7 @@ static inline void *folio_raw_mapping(const struct folio *folio)
>   */
>  static inline int mmap_file(struct file *file, struct vm_area_struct *vma)
>  {
> -	int err = call_mmap(file, vma);
> +	int err = vfs_mmap(file, vma);
>  
>  	if (likely(!err))
>  		return 0;
> diff --git a/mm/vma.c b/mm/vma.c
> index 5d35adadf2b5..f548bede3bbe 100644
> --- a/mm/vma.c
> +++ b/mm/vma.c
> @@ -2582,7 +2582,7 @@ static int call_mmap_prepare(struct mmap_state *map)
>  	};
>  
>  	/* Invoke the hook. */
> -	err = __call_mmap_prepare(map->file, &desc);
> +	err = vfs_mmap_prepare(map->file, &desc);
>  	if (err)
>  		return err;
>  
> diff --git a/tools/testing/vma/vma_internal.h b/tools/testing/vma/vma_internal.h
> index d7fea56e3bb3..51dd122b8d50 100644
> --- a/tools/testing/vma/vma_internal.h
> +++ b/tools/testing/vma/vma_internal.h
> @@ -1458,6 +1458,27 @@ static inline void free_anon_vma_name(struct vm_area_struct *vma)
>  	(void)vma;
>  }
>  
> +/* Declared in vma.h. */
> +static inline void set_vma_from_desc(struct vm_area_struct *vma,
> +		struct vm_area_desc *desc);
> +
> +static inline struct vm_area_desc *vma_to_desc(struct vm_area_struct *vma,
> +		struct vm_area_desc *desc);
> +
> +static int compat_vma_mmap_prepare(struct file *file,
> +		struct vm_area_struct *vma)
> +{
> +	struct vm_area_desc desc;
> +	int err;
> +
> +	err = file->f_op->mmap_prepare(vma_to_desc(vma, &desc));
> +	if (err)
> +		return err;
> +	set_vma_from_desc(vma, &desc);
> +
> +	return 0;
> +}
> +
>  /* Did the driver provide valid mmap hook configuration? */
>  static inline bool file_has_valid_mmap_hooks(struct file *file)
>  {
> @@ -1467,22 +1488,21 @@ static inline bool file_has_valid_mmap_hooks(struct file *file)
>  	/* Hooks are mutually exclusive. */
>  	if (WARN_ON_ONCE(has_mmap && has_mmap_prepare))
>  		return false;
> -	if (WARN_ON_ONCE(!has_mmap && !has_mmap_prepare))
> +	if (!has_mmap && !has_mmap_prepare)
>  		return false;
>  
>  	return true;
>  }
>  
> -static inline int call_mmap(struct file *file, struct vm_area_struct *vma)
> +static inline int vfs_mmap(struct file *file, struct vm_area_struct *vma)
>  {
> -	if (WARN_ON_ONCE(file->f_op->mmap_prepare))
> -		return -EINVAL;
> +	if (file->f_op->mmap_prepare)
> +		return compat_vma_mmap_prepare(file, vma);
>  
>  	return file->f_op->mmap(file, vma);
>  }
>  
> -static inline int __call_mmap_prepare(struct file *file,
> -		struct vm_area_desc *desc)
> +static inline int vfs_mmap_prepare(struct file *file, struct vm_area_desc *desc)
>  {
>  	return file->f_op->mmap_prepare(desc);
>  }