linux-kernel - Re: [PATCH 2/6] shmem: rename functions that are memfd-related

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Date:   Wed, 1 Nov 2017 16:01:30 -0700
From:   Mike Kravetz <mike.kravetz@...cle.com>
To:     Marc-André Lureau <marcandre.lureau@...hat.com>,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc:     aarcange@...hat.com, hughd@...gle.com, nyc@...omorphy.com
Subject: Re: [PATCH 2/6] shmem: rename functions that are memfd-related

On 10/31/2017 11:40 AM, Marc-André Lureau wrote:
> Those functions are called for memfd files, backed by shmem or
> hugetlb (the next patches will handle hugetlb).
> 
> Signed-off-by: Marc-André Lureau <marcandre.lureau@...hat.com>
> ---
>  fs/fcntl.c               |  2 +-
>  include/linux/shmem_fs.h |  4 ++--
>  mm/shmem.c               | 10 +++++-----
>  3 files changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/fs/fcntl.c b/fs/fcntl.c
> index 448a1119f0be..752c23743616 100644
> --- a/fs/fcntl.c
> +++ b/fs/fcntl.c
> @@ -417,7 +417,7 @@ static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
>  		break;
>  	case F_ADD_SEALS:
>  	case F_GET_SEALS:
> -		err = shmem_fcntl(filp, cmd, arg);
> +		err = memfd_fcntl(filp, cmd, arg);
>  		break;
>  	case F_GET_RW_HINT:
>  	case F_SET_RW_HINT:
> diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
> index 557d0c3b6eca..0dac8c0f4aa4 100644
> --- a/include/linux/shmem_fs.h
> +++ b/include/linux/shmem_fs.h
> @@ -109,11 +109,11 @@ extern void shmem_uncharge(struct inode *inode, long pages);
>  
>  #ifdef CONFIG_TMPFS
>  
> -extern long shmem_fcntl(struct file *file, unsigned int cmd, unsigned long arg);
> +extern long memfd_fcntl(struct file *file, unsigned int cmd, unsigned long arg);
>  
>  #else
>  
> -static inline long shmem_fcntl(struct file *f, unsigned int c, unsigned long a)
> +static inline long memfd_fcntl(struct file *f, unsigned int c, unsigned long a)
>  {
>  	return -EINVAL;
>  }

Do we want memfd_fcntl() to work for hugetlbfs if CONFIG_TMPFS is not
defined?  I admit that having CONFIG_HUGETLBFS defined without CONFIG_TMPFS
is unlikely, but I think possible.  Based on the above #ifdef/#else, I
think hugetlbfs seals will not work if CONFIG_TMPFS is not defined.

-- 
Mike Kravetz

> diff --git a/mm/shmem.c b/mm/shmem.c
> index 37260c5e12fa..b7811979611f 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -2722,7 +2722,7 @@ static int shmem_wait_for_pins(struct address_space *mapping)
>  		     F_SEAL_GROW | \
>  		     F_SEAL_WRITE)
>  
> -static int shmem_add_seals(struct file *file, unsigned int seals)
> +static int memfd_add_seals(struct file *file, unsigned int seals)
>  {
>  	struct inode *inode = file_inode(file);
>  	struct shmem_inode_info *info = SHMEM_I(inode);
> @@ -2792,7 +2792,7 @@ static int shmem_add_seals(struct file *file, unsigned int seals)
>  	return error;
>  }
>  
> -static int shmem_get_seals(struct file *file)
> +static int memfd_get_seals(struct file *file)
>  {
>  	if (file->f_op != &shmem_file_operations)
>  		return -EINVAL;
> @@ -2800,7 +2800,7 @@ static int shmem_get_seals(struct file *file)
>  	return SHMEM_I(file_inode(file))->seals;
>  }
>  
> -long shmem_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
> +long memfd_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
>  {
>  	long error;
>  
> @@ -2810,10 +2810,10 @@ long shmem_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
>  		if (arg > UINT_MAX)
>  			return -EINVAL;
>  
> -		error = shmem_add_seals(file, arg);
> +		error = memfd_add_seals(file, arg);
>  		break;
>  	case F_GET_SEALS:
> -		error = shmem_get_seals(file);
> +		error = memfd_get_seals(file);
>  		break;
>  	default:
>  		error = -EINVAL;
>