Re: [PATCH Version-2 03/12] VFS permit cross device vfs_copy_file_range

["J. Bruce Fields" <bfields@fieldses.org>]

I thought I remembered Christoph (cc'd) arguing at the 2015 lsf/mm that
there were some more issues that would need to be taken care of before
we could turn on cross-device copies.

But maybe I misremember.  In any case, I don't remember what the issues
were....

--b.

On Fri, Aug 19, 2016 at 01:25:03PM -0400, andros@netapp.com wrote:
> From: Andy Adamson <andros@rhel7-2-ga-3.androsad.fake>
> 
> NFSv4.2 inter server to server copy always copies across devices.
> 
> Note: both btrfs and nfs have EXDEV checks in their
> copy_file_range functions.
> 
> Signed-off-by: Andy Adamson <andros@netapp.com>
> ---
>  fs/read_write.c | 5 -----
>  1 file changed, 5 deletions(-)
> 
> diff --git a/fs/read_write.c b/fs/read_write.c
> index 1cbab4e..a6d3350 100644
> --- a/fs/read_write.c
> +++ b/fs/read_write.c
> @@ -1483,7 +1483,6 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
>  			    size_t len, unsigned int flags)
>  {
>  	struct inode *inode_in = file_inode(file_in);
> -	struct inode *inode_out = file_inode(file_out);
>  	ssize_t ret;
>  
>  	if (flags != 0)
> @@ -1505,10 +1504,6 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
>  	    (file_out->f_flags & O_APPEND))
>  		return -EBADF;
>  
> -	/* this could be relaxed once a method supports cross-fs copies */
> -	if (inode_in->i_sb != inode_out->i_sb)
> -		return -EXDEV;
> -
>  	if (len == 0)
>  		return 0;
>  
> -- 
> 1.8.3.1