linux-kernel - Re: [PATCH v2 1/1] mm: move ->mremap() from file_operations to vm_operations

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Message-ID: <20150625220829.GA25673@node.dhcp.inet.fi>
Date:	Fri, 26 Jun 2015 01:08:29 +0300
From:	"Kirill A. Shutemov" <kirill@...temov.name>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Andy Lutomirski <luto@...capital.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Al Viro <viro@...iv.linux.org.uk>,
	Benjamin LaHaise <bcrl@...ck.org>,
	Hugh Dickins <hughd@...gle.com>,
	Jeff Moyer <jmoyer@...hat.com>,
	Kirill Shutemov <kirill.shutemov@...ux.intel.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Andy Lutomirski <luto@...nel.org>,
	Pavel Emelyanov <xemul@...allels.com>
Subject: Re: [PATCH v2 1/1] mm: move ->mremap() from file_operations to
 vm_operations_struct

On Thu, Jun 25, 2015 at 10:45:04PM +0200, Oleg Nesterov wrote:
> vma->vm_ops->mremap() looks more natural and clean in move_vma(),
> and this way ->mremap() can have more users. Say, vdso.
> 
> While at it, s/aio_ring_remap/aio_ring_mremap/.
> 
> Signed-off-by: Oleg Nesterov <oleg@...hat.com>
> ---
>  fs/aio.c           |   25 ++++++++++++++++---------
>  include/linux/fs.h |    1 -
>  include/linux/mm.h |    1 +
>  mm/mremap.c        |    4 ++--
>  4 files changed, 19 insertions(+), 12 deletions(-)
> 
> diff --git a/fs/aio.c b/fs/aio.c
> index 9bc1335..a632f14 100644
> --- a/fs/aio.c
> +++ b/fs/aio.c
> @@ -308,15 +308,9 @@ static void aio_free_ring(struct kioctx *ctx)
>  	}
>  }
>  
> -static int aio_ring_mmap(struct file *file, struct vm_area_struct *vma)
> -{
> -	vma->vm_flags |= VM_DONTEXPAND;
> -	vma->vm_ops = &generic_file_vm_ops;
> -	return 0;
> -}
> -
> -static int aio_ring_remap(struct file *file, struct vm_area_struct *vma)
> +static int aio_ring_mremap(struct vm_area_struct *vma)
>  {
> +	struct file *file = vma->vm_file;
>  	struct mm_struct *mm = vma->vm_mm;
>  	struct kioctx_table *table;
>  	int i, res = -EINVAL;
> @@ -339,9 +333,22 @@ static int aio_ring_remap(struct file *file, struct vm_area_struct *vma)
>  	return res;
>  }
>  
> +static const struct vm_operations_struct aio_ring_vm_ops = {
> +	.mremap		= aio_ring_mremap,
> +	.fault		= filemap_fault,
> +	.map_pages	= filemap_map_pages,
> +	.page_mkwrite	= filemap_page_mkwrite,
> +};
> +
> +static int aio_ring_mmap(struct file *file, struct vm_area_struct *vma)
> +{
> +	vma->vm_flags |= VM_DONTEXPAND;
> +	vma->vm_ops = &aio_ring_vm_ops;
> +	return 0;
> +}
> +
>  static const struct file_operations aio_ring_fops = {
>  	.mmap = aio_ring_mmap,
> -	.mremap = aio_ring_remap,
>  };
>  
>  #if IS_ENABLED(CONFIG_MIGRATION)
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 35ec87e..42aac09 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1582,7 +1582,6 @@ struct file_operations {
>  	long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);
>  	long (*compat_ioctl) (struct file *, unsigned int, unsigned long);
>  	int (*mmap) (struct file *, struct vm_area_struct *);
> -	int (*mremap)(struct file *, struct vm_area_struct *);
>  	int (*open) (struct inode *, struct file *);
>  	int (*flush) (struct file *, fl_owner_t id);
>  	int (*release) (struct inode *, struct file *);
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index a0fe3d3..0295b4a 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -244,6 +244,7 @@ struct vm_fault {
>  struct vm_operations_struct {
>  	void (*open)(struct vm_area_struct * area);
>  	void (*close)(struct vm_area_struct * area);
> +	int (*mremap)(struct vm_area_struct * area);
>  	int (*fault)(struct vm_area_struct *vma, struct vm_fault *vmf);
>  	void (*map_pages)(struct vm_area_struct *vma, struct vm_fault *vmf);
>  
> diff --git a/mm/mremap.c b/mm/mremap.c
> index ed1b13a..aeba807 100644
> --- a/mm/mremap.c
> +++ b/mm/mremap.c
> @@ -276,8 +276,8 @@ static unsigned long move_vma(struct vm_area_struct *vma,
>  				     need_rmap_locks);
>  	if (moved_len < old_len) {
>  		err = -ENOMEM;
> -	} else if (vma->vm_file && vma->vm_file->f_op->mremap) {
> -		err = vma->vm_file->f_op->mremap(vma->vm_file, new_vma);
> +	} else if (vma->vm_ops && vma->vm_ops->mremap) {
> +		err = vma->vm_ops->mremap(new_vma);
>  	}
>  
>  	if (unlikely(err)) {

I'm not sure what is target tree for the patch. Last hunk is not going to
apply on Linus' tree or -next. Hm?

Otherwise, looks good.

Acked-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>

-- 
 Kirill A. Shutemov
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