Re: [PATCH v3 2/3] mm, dax: make pmd_fault() and friends to be the same as fault()

[Ross Zwisler <ross.zwisler@linux.intel.com>]

On Thu, Dec 15, 2016 at 01:51:05PM -0700, Dave Jiang wrote:
> Instead of passing in multiple parameters in the pmd_fault() handler,
> a vmf can be passed in just like a fault() handler. This will simplify
> code and remove the need for the actual pmd fault handlers to allocate a
> vmf. Related functions are also modified to do the same.
> 
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
> Reviewed-by: Jan Kara <jack@suse.cz>
> ---

> diff --git a/fs/ext4/file.c b/fs/ext4/file.c
> index a3f2bf0..e6cdb78 100644
> --- a/fs/ext4/file.c
> +++ b/fs/ext4/file.c
> @@ -278,22 +278,26 @@ static int ext4_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
>  	return result;
>  }
>  
> -static int ext4_dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
> -						pmd_t *pmd, unsigned int flags)
> +static int
> +ext4_dax_pmd_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
>  {
>  	int result;
>  	struct inode *inode = file_inode(vma->vm_file);
>  	struct super_block *sb = inode->i_sb;
> -	bool write = flags & FAULT_FLAG_WRITE;
> +	bool write = vmf->flags & FAULT_FLAG_WRITE;
> +	gfp_t old_mask;
>  
>  	if (write) {
>  		sb_start_pagefault(sb);
>  		file_update_time(vma->vm_file);
>  	}
> +
> +	old_mask = vmf->gfp_mask;
> +	vmf->gfp_mask &= ~__GFP_FS;
>  	down_read(&EXT4_I(inode)->i_mmap_sem);
> -	result = dax_iomap_pmd_fault(vma, addr, pmd, flags,
> -				     &ext4_iomap_ops);
> +	result = dax_iomap_pmd_fault(vma, vmf, &ext4_iomap_ops);
>  	up_read(&EXT4_I(inode)->i_mmap_sem);
> +	vmf->gfp_mask = old_mask;
>  	if (write)
>  		sb_end_pagefault(sb);
>  
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index 52202b4..b1b8524 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -1533,29 +1533,31 @@ xfs_filemap_fault(
>  STATIC int
>  xfs_filemap_pmd_fault(
>  	struct vm_area_struct	*vma,
> -	unsigned long		addr,
> -	pmd_t			*pmd,
> -	unsigned int		flags)
> +	struct vm_fault *vmf)
>  {
>  	struct inode		*inode = file_inode(vma->vm_file);
>  	struct xfs_inode	*ip = XFS_I(inode);
>  	int			ret;
> +	gfp_t			old_mask;
>  
>  	if (!IS_DAX(inode))
>  		return VM_FAULT_FALLBACK;
>  
>  	trace_xfs_filemap_pmd_fault(ip);
>  
> -	if (flags & FAULT_FLAG_WRITE) {
> +	if (vmf->flags & FAULT_FLAG_WRITE) {
>  		sb_start_pagefault(inode->i_sb);
>  		file_update_time(vma->vm_file);
>  	}
>  
> +	old_mask = vmf->gfp_mask;

One small nit for both xfs and ext4 - in patch 1 you named your local
'old_gfp' and set it when it was defined, but in this patch it's 'old_mask'
and it's set later.  Probably best to keep this patch consistent with the
first one.

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