diff --git a/fs/read_write.c b/fs/read_write.c
index 819ef3faf1bb710678175de06a13f4dcf6e90d62..173140029a7ad4e11f83eff56471af91f60d23c8 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -16,6 +16,7 @@
#include <linux/pagemap.h>
#include <linux/splice.h>
#include <linux/compat.h>
+#include <linux/mount.h>
#include "internal.h"
#include <asm/uaccess.h>
@@ -1327,3 +1328,122 @@ COMPAT_SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd,
return do_sendfile(out_fd, in_fd, NULL, count, 0);
}
#endif
+
+/*
+ * 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
+ * the copy_file_range method.
+ */
+ssize_t vfs_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)
+{
+ struct inode *inode_in = file_inode(file_in);
+ struct inode *inode_out = file_inode(file_out);
+ ssize_t ret;
+
+ if (flags != 0)
+ return -EINVAL;
+
+ /* copy_file_range allows full ssize_t len, ignoring MAX_RW_COUNT */
+ ret = rw_verify_area(READ, file_in, &pos_in, len);
+ if (ret >= 0)
+ ret = rw_verify_area(WRITE, file_out, &pos_out, len);
+ if (ret < 0)
+ return ret;
+
+ if (!(file_in->f_mode & FMODE_READ) ||
+ !(file_out->f_mode & FMODE_WRITE) ||
+ (file_out->f_flags & O_APPEND) ||
+ !file_out->f_op->copy_file_range)
+ 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;
+
+ ret = mnt_want_write_file(file_out);
+ if (ret)
+ return ret;
+
+ ret = file_out->f_op->copy_file_range(file_in, pos_in, file_out, pos_out,
+ len, flags);
+ if (ret > 0) {
+ fsnotify_access(file_in);
+ add_rchar(current, ret);
+ fsnotify_modify(file_out);
+ add_wchar(current, ret);
+ }
+ inc_syscr(current);
+ inc_syscw(current);
+
+ mnt_drop_write_file(file_out);
+
+ return ret;
+}
+EXPORT_SYMBOL(vfs_copy_file_range);
+
+SYSCALL_DEFINE6(copy_file_range, int, fd_in, loff_t __user *, off_in,
+ int, fd_out, loff_t __user *, off_out,
+ size_t, len, unsigned int, flags)
+{
+ loff_t pos_in;
+ loff_t pos_out;
+ struct fd f_in;
+ struct fd f_out;
+ ssize_t ret = -EBADF;
+
+ f_in = fdget(fd_in);
+ if (!f_in.file)
+ goto out2;
+
+ f_out = fdget(fd_out);
+ if (!f_out.file)
+ goto out1;
+
+ ret = -EFAULT;
+ if (off_in) {
+ if (copy_from_user(&pos_in, off_in, sizeof(loff_t)))
+ goto out;
+ } else {
+ pos_in = f_in.file->f_pos;
+ }
+
+ if (off_out) {
+ if (copy_from_user(&pos_out, off_out, sizeof(loff_t)))
+ goto out;
+ } else {
+ pos_out = f_out.file->f_pos;
+ }
+
+ ret = vfs_copy_file_range(f_in.file, pos_in, f_out.file, pos_out, len,
+ flags);
+ if (ret > 0) {
+ pos_in += ret;
+ pos_out += ret;
+
+ if (off_in) {
+ if (copy_to_user(off_in, &pos_in, sizeof(loff_t)))
+ ret = -EFAULT;
+ } else {
+ f_in.file->f_pos = pos_in;
+ }
+
+ if (off_out) {
+ if (copy_to_user(off_out, &pos_out, sizeof(loff_t)))
+ ret = -EFAULT;
+ } else {
+ f_out.file->f_pos = pos_out;
+ }
+ }
+
+out:
+ fdput(f_out);
+out1:
+ fdput(f_in);
+out2:
+ return ret;
+}
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 3aa51425416148f5bec14b6faf4e6f4e81370a22..e8a736242b1af71a50b79e8210629ed6852886dc 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1629,6 +1629,7 @@ struct file_operations {
#ifndef CONFIG_MMU
unsigned (*mmap_capabilities)(struct file *);
#endif
+ ssize_t (*copy_file_range)(struct file *, loff_t, struct file *, loff_t, size_t, unsigned int);
};
struct inode_operations {
@@ -1680,6 +1681,8 @@ extern ssize_t vfs_readv(struct file *, const struct iovec __user *,
unsigned long, loff_t *);
extern ssize_t vfs_writev(struct file *, const struct iovec __user *,
unsigned long, loff_t *);
+extern ssize_t vfs_copy_file_range(struct file *, loff_t , struct file *,
+ loff_t, size_t, unsigned int);
struct super_operations {
struct inode *(*alloc_inode)(struct super_block *sb);
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index c2b66a277e9807de8a224879793c121df63f7d69..185815c964330e017a622aafeec0a1865efaf22e 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -886,6 +886,9 @@ asmlinkage long sys_execveat(int dfd, const char __user *filename,
const char __user *const __user *envp, int flags);
asmlinkage long sys_membarrier(int cmd, int flags);
+asmlinkage long sys_copy_file_range(int fd_in, loff_t __user *off_in,
+ int fd_out, loff_t __user *off_out,
+ size_t len, unsigned int flags);
asmlinkage long sys_mlock2(unsigned long start, size_t len, int flags);
diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
index 1324b0292ec28ed7ed61f1dc875d1fd84503a6d1..2622b33fb2ec7d0e37e437198ac5d1637eed224d 100644
--- a/include/uapi/asm-generic/unistd.h
+++ b/include/uapi/asm-generic/unistd.h
@@ -715,9 +715,11 @@ __SYSCALL(__NR_userfaultfd, sys_userfaultfd)
__SYSCALL(__NR_membarrier, sys_membarrier)
#define __NR_mlock2 284
__SYSCALL(__NR_mlock2, sys_mlock2)
+#define __NR_copy_file_range 285
+__SYSCALL(__NR_copy_file_range, sys_copy_file_range)
#undef __NR_syscalls
-#define __NR_syscalls 285
+#define __NR_syscalls 286
/*
* All syscalls below here should go away really,
diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index 0623787ec67af5fb95f505b55c1577a2f56ce0f4..2c5e3a8e00d7bd152c045549d68458c1b76e253f 100644
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c
@@ -174,6 +174,7 @@ cond_syscall(sys_setfsuid);
cond_syscall(sys_setfsgid);
cond_syscall(sys_capget);
cond_syscall(sys_capset);
+cond_syscall(sys_copy_file_range);
/* arch-specific weak syscall entries */
cond_syscall(sys_pciconfig_read);