Re: [PATCH 01/18] vfs: introduce new file range exchange ioctl

From: Darrick J. Wong <djwong@kernel.org>

Introduce a new ioctl to handle swapping ranges of bytes between files.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
 Documentation/filesystems/vfs.rst |   16 ++
 fs/ioctl.c                        |   42 +++++
 fs/remap_range.c                  |  283 +++++++++++++++++++++++++++++++++++++
 fs/xfs/libxfs/xfs_fs.h            |    1
 include/linux/fs.h                |   14 ++
 include/uapi/linux/fiexchange.h   |  101 +++++++++++++
 6 files changed, 456 insertions(+), 1 deletion(-)
 create mode 100644 include/uapi/linux/fiexchange.h

diff --git a/Documentation/filesystems/vfs.rst b/Documentation/filesystems/vfs.rst
index 2049bbf5e388..9f16b260bc7e 100644
--- a/Documentation/filesystems/vfs.rst
+++ b/Documentation/filesystems/vfs.rst

@@ -1006,6 +1006,8 @@ This describes how the VFS can manipulate an open file.  As of kernel
                loff_t (*remap_file_range)(struct file *file_in, loff_t pos_in,
                                           struct file *file_out, loff_t pos_out,
                                           loff_t len, unsigned int remap_flags);
+                int (*xchg_file_range)(struct file *file1, struct file *file2,
+                                       struct file_xchg_range *fxr);