cp --reflink: add an "auto" parameter to fall back to a normal copy

* doc/coreutils.texi (cp invocation): Document the new
"auto" and "always" options to --reflink.
* src/copy.c (copy_reg): Fall back to a standard copy
when reflink() is not supported and --reflink=auto specified.
* src/copy.h [struct cp_options] (reflink): Change type s/bool/enum/.
* src/cp.c (usage): Describe the --reflink={always,auto} options
and expand a little on what --reflink does.
(main): parse the new parameters to --reflink and allow all
--sparse options with --reflink=auto.
* src/install.c (cp_option_init): Init the enum instead of bool.
* src/mv.c (cp_option_init): Likewise.
* tests/cp/reflink-auto: A new test for falling back to normal copy.
* tests/Makefile.am: Reference the new test.
* NEWS: Mention the new feature.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/install.c b/src/install.c
index a4e0cab32..fafa21a3c 100644
--- a/src/install.c
+++ b/src/install.c
@@ -269,7 +269,7 @@ cp_option_init (struct cp_options *x)
 {
   cp_options_default (x);
   x->copy_as_regular = true;
-  x->reflink = false;
+  x->reflink_mode = REFLINK_NEVER;
   x->dereference = DEREF_ALWAYS;
   x->unlink_dest_before_opening = true;
   x->unlink_dest_after_failed_open = false;