io: Remove copy_file_range emulation [BZ #24744]

The kernel is evolving this interface (e.g., removal of the
restriction on cross-device copies), and keeping up with that
is difficult.  Applications which need the function should
run kernels which support the system call instead of relying on
the imperfect glibc emulation.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/NEWS b/NEWS
index 8a2fecef47..650b81a2e7 100644
--- a/NEWS
+++ b/NEWS
@@ -36,6 +36,14 @@ Major new features:
 
 Deprecated and removed features, and other changes affecting compatibility:
 
+* The copy_file_range function fails with ENOSYS if the kernel does not
+  support the system call of the same name.  Previously, user space
+  emulation was performed, but its behavior did not match the kernel
+  behavior, which was deemed too confusing.  Applications which use the
+  copy_file_range function will have to be run on kernels which implement
+  the copy_file_range system call.  Support for most architectures was added
+  in version 4.5 of the mainline Linux kernel.
+
 * The functions clock_gettime, clock_getres, clock_settime,
   clock_getcpuclockid, clock_nanosleep were removed from the librt library
   for new applications (on architectures which had them).  Instead, the