RENAME_NOREPLACE is trivial to implement for most filesystems: switch over
to ->rename2() and check for the supported flags. The rest is done by the
VFS.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Cc: Chris Mason <clm@fb.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>