Re: [PATCH 03/11] vfs: no fallback for ->copy_file_range

[Anna Schumaker <schumaker.anna@gmail.com>]

Hi Dave,

On Mon, 2018-12-03 at 19:34 +1100, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
> 
> Now that we have generic_copy_file_range(), remove it as a fallback
> case when offloads fail. This puts the responsibility for executing
> fallbacks on the filesystems that implement ->copy_file_range and
> allows us to add operational validity checks to
> generic_copy_file_range().
> 
> Rework vfs_copy_file_range() to call a new do_copy_file_range()
> helper to exceute the copying callout, and move calls to
> generic_file_copy_range() into filesystem methods where they
> currently return failures.
> 
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> ---
>  fs/ceph/file.c      | 17 ++++++++++++++++-
>  fs/cifs/cifsfs.c    |  4 ++++
>  fs/fuse/file.c      | 17 ++++++++++++++++-
>  fs/nfs/nfs4file.c   |  4 ++++

The NFS bits look okay to me:
Acked-by: Anna Schumaker <Anna.Schumaker@Netapp.com

>  fs/overlayfs/file.c |  9 ++++++++-
>  fs/read_write.c     | 24 +++++++++++++++---------
>  6 files changed, 63 insertions(+), 12 deletions(-)
> 
> diff --git a/fs/ceph/file.c b/fs/ceph/file.c
> index 189df668b6a0..cf29f0410dcb 100644
> --- a/fs/ceph/file.c
> +++ b/fs/ceph/file.c
> @@ -1885,7 +1885,7 @@ static int is_file_size_ok(struct inode *src_inode,
> struct inode *dst_inode,
>  	return 0;
>  }
>  
> -static ssize_t ceph_copy_file_range(struct file *src_file, loff_t src_off,
> +static ssize_t __ceph_copy_file_range(struct file *src_file, loff_t src_off,
>  				    struct file *dst_file, loff_t dst_off,
>  				    size_t len, unsigned int flags)
>  {
> @@ -2096,6 +2096,21 @@ static ssize_t ceph_copy_file_range(struct file
> *src_file, loff_t src_off,
>  	return ret;
>  }
>  
> +static ssize_t ceph_copy_file_range(struct file *src_file, loff_t src_off,
> +				    struct file *dst_file, loff_t dst_off,
> +				    size_t len, unsigned int flags)
> +{
> +	ssize_t ret;
> +
> +	ret = __ceph_copy_file_range(src_file, src_off, dst_file, dst_off,
> +					len, flags);
> +
> +	if (ret == -EOPNOTSUPP)
> +		ret = generic_copy_file_range(src_file, src_off, dst_file,
> +					dst_off, len, flags);
> +	return ret;
> +}
> +
>  const struct file_operations ceph_file_fops = {
>  	.open = ceph_open,
>  	.release = ceph_release,
> diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
> index 865706edb307..5ef4baec6234 100644
> --- a/fs/cifs/cifsfs.c
> +++ b/fs/cifs/cifsfs.c
> @@ -1141,6 +1141,10 @@ static ssize_t cifs_copy_file_range(struct file
> *src_file, loff_t off,
>  	rc = cifs_file_copychunk_range(xid, src_file, off, dst_file, destoff,
>  					len, flags);
>  	free_xid(xid);
> +
> +	if (rc == -EOPNOTSUPP)
> +		rc = generic_copy_file_range(src_file, off, dst_file,
> +					destoff, len, flags);
>  	return rc;
>  }
>  
> diff --git a/fs/fuse/file.c b/fs/fuse/file.c
> index b52f9baaa3e7..b86fb0298739 100644
> --- a/fs/fuse/file.c
> +++ b/fs/fuse/file.c
> @@ -3024,7 +3024,7 @@ static long fuse_file_fallocate(struct file *file, int
> mode, loff_t offset,
>  	return err;
>  }
>  
> -static ssize_t fuse_copy_file_range(struct file *file_in, loff_t pos_in,
> +static ssize_t __fuse_copy_file_range(struct file *file_in, loff_t pos_in,
>  				    struct file *file_out, loff_t pos_out,
>  				    size_t len, unsigned int flags)
>  {
> @@ -3100,6 +3100,21 @@ static ssize_t fuse_copy_file_range(struct file
> *file_in, loff_t pos_in,
>  	return err;
>  }
>  
> +static ssize_t fuse_copy_file_range(struct file *src_file, loff_t src_off,
> +				    struct file *dst_file, loff_t dst_off,
> +				    size_t len, unsigned int flags)
> +{
> +	ssize_t ret;
> +
> +	ret = __fuse_copy_file_range(src_file, src_off, dst_file, dst_off,
> +					len, flags);
> +
> +	if (ret == -EOPNOTSUPP)
> +		ret = generic_copy_file_range(src_file, src_off, dst_file,
> +					dst_off, len, flags);
> +	return ret;
> +}
> +
>  static const struct file_operations fuse_file_operations = {
>  	.llseek		= fuse_file_llseek,
>  	.read_iter	= fuse_file_read_iter,
> diff --git a/fs/nfs/nfs4file.c b/fs/nfs/nfs4file.c
> index 46d691ba04bc..d7766a6eb0f4 100644
> --- a/fs/nfs/nfs4file.c
> +++ b/fs/nfs/nfs4file.c
> @@ -141,6 +141,10 @@ static ssize_t nfs4_copy_file_range(struct file *file_in,
> loff_t pos_in,
>  	ret = nfs42_proc_copy(file_in, pos_in, file_out, pos_out, count);
>  	if (ret == -EAGAIN)
>  		goto retry;
> +
> +	if (ret == -EOPNOTSUPP)
> +		ret = generic_copy_file_range(file_in, pos_in, file_out,
> +					pos_out, count, flags);
>  	return ret;
>  }
>  
> diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
> index 84dd957efa24..68736e5d6a56 100644
> --- a/fs/overlayfs/file.c
> +++ b/fs/overlayfs/file.c
> @@ -486,8 +486,15 @@ static ssize_t ovl_copy_file_range(struct file *file_in,
> loff_t pos_in,
>  				   struct file *file_out, loff_t pos_out,
>  				   size_t len, unsigned int flags)
>  {
> -	return ovl_copyfile(file_in, pos_in, file_out, pos_out, len, flags,
> +	ssize_t ret;
> +
> +	ret =  ovl_copyfile(file_in, pos_in, file_out, pos_out, len, flags,
>  			    OVL_COPY);
> +
> +	if (ret == -EOPNOTSUPP)
> +		ret = generic_copy_file_range(file_in, pos_in, file_out,
> +					pos_out, len, flags);
> +	return ret;
>  }
>  
>  static loff_t ovl_remap_file_range(struct file *file_in, loff_t pos_in,
> diff --git a/fs/read_write.c b/fs/read_write.c
> index 50114694c98b..44339b44accc 100644
> --- a/fs/read_write.c
> +++ b/fs/read_write.c
> @@ -1570,6 +1570,18 @@ ssize_t generic_copy_file_range(struct file *file_in,
> loff_t pos_in,
>  }
>  EXPORT_SYMBOL(generic_copy_file_range);
>  
> +static ssize_t do_copy_file_range(struct file *file_in, loff_t pos_in,
> +			    struct file *file_out, loff_t pos_out,
> +			    size_t len, unsigned int flags)
> +{
> +	if (file_out->f_op->copy_file_range)
> +		return file_out->f_op->copy_file_range(file_in, pos_in,
> file_out,
> +						      pos_out, len, flags);
> +
> +	return generic_copy_file_range(file_in, &pos_in, file_out, &pos_out,
> +					len, flags);
> +}
> +
>  /*
>   * copy_file_range() differs from regular file read and write in that it
>   * specifically allows return partial success.  When it does so is up to
> @@ -1634,15 +1646,9 @@ ssize_t vfs_copy_file_range(struct file *file_in,
> loff_t pos_in,
>  		}
>  	}
>  
> -	if (file_out->f_op->copy_file_range) {
> -		ret = file_out->f_op->copy_file_range(file_in, pos_in, file_out,
> -						      pos_out, len, flags);
> -		if (ret != -EOPNOTSUPP)
> -			goto done;
> -	}
> -
> -	ret = generic_copy_file_range(file_in, &pos_in, file_out, &pos_out,
> -					len, flags);
> +	ret = do_copy_file_range(file_in, pos_in, file_out, pos_out, len,
> +				flags);
> +	WARN_ON_ONCE(ret == -EOPNOTSUPP);
>  done:
>  	if (ret > 0) {
>  		fsnotify_access(file_in);