On Thu, Aug 27, 2015 at 6:52 AM, Dave Chinner [off-list ref] wrote:

On Wed, Aug 26, 2015 at 04:16:42PM +0800, Peng Tao wrote:

quoted

Now that a few file systems are adding clone functionality, namingly
btrfs, NFS (later in the series) and XFS
(ttp://oss.sgi.com/archives/xfs/2015-06/msg00407.html), it makes sense
to pull the ioctl to common code.

Add vfs_file_clone_range() helper and .clone_range file operation interface
to allow underlying filesystems to clone between regular files.

The change in do_vfs_ioctl() is defered to next patch where btrfs
.clone_range is added, just so that we don't break btrfs CLONE ioctl
with this patch.

Signed-off-by: Peng Tao <redacted>
---
 fs/ioctl.c              | 24 ++++++++++++++++++++++++
 fs/read_write.c         | 45 +++++++++++++++++++++++++++++++++++++++++++++
 include/linux/fs.h      |  4 ++++
 include/uapi/linux/fs.h |  9 +++++++++
 4 files changed, 82 insertions(+)

.....

quoted

+int vfs_file_clone_range(struct file *src_file, struct file *dst_file,
+                      loff_t off, size_t len, loff_t dstoff)
+{
+     struct inode *src_ino;
+     struct inode *dst_ino;
+     ssize_t ret;
+
+     if (!(src_file->f_mode & FMODE_READ) ||
+         !(dst_file->f_mode & FMODE_WRITE) ||
+         (dst_file->f_flags & O_APPEND) ||
+         !src_file->f_op || !src_file->f_op->clone_range)
+             return -EINVAL;
+
+     src_ino = file_inode(src_file);
+     dst_ino = file_inode(dst_file);
+
+        if (S_ISDIR(src_ino->i_mode) || S_ISDIR(dst_ino->i_mode))
+                return -EISDIR;

Whacky whitespace.

Also, shouldn't this call be restricted to S_ISREG() inodes? This
only checks for directories...

Good point. I'll change it. Thanks!

Cheers,
Tao