svn commit: r365549 - head/bin/cp

[Alan Somers]

Author: asomers
Date: Thu Sep 10 02:48:55 2020
New Revision: 365549
URL: https://svnweb.freebsd.org/changeset/base/365549

Log:
  cp: use copy_file_range(2)
  
  This has three advantages over write(2)/read(2):
  
  * Fewer context switches and data copies
  * Mostly preserves a file's sparseness
  * On some file systems (currently NFS 4.2) the file system will perform the
    copy in an especially efficient way.
  
  Reviewed by:	rmacklem
  MFC after:	2 weeks
  Sponsored by:	Axcient
  Differential Revision:	https://reviews.freebsd.org/D26377

Modified:
  head/bin/cp/utils.c

Modified: head/bin/cp/utils.c
==============================================================================
--- head/bin/cp/utils.c	Thu Sep 10 01:49:53 2020	(r365548)
+++ head/bin/cp/utils.c	Thu Sep 10 02:48:55 2020	(r365549)
@@ -212,27 +212,16 @@ copy_file(const FTSENT *entp, int dne)
 					err(1, "Not enough memory");
 			}
 			wtotal = 0;
-			while ((rcount = read(from_fd, buf, bufsize)) > 0) {
-				for (bufp = buf, wresid = rcount; ;
-				    bufp += wcount, wresid -= wcount) {
-					wcount = write(to_fd, bufp, wresid);
-					if (wcount <= 0)
-						break;
-					wtotal += wcount;
-					if (info) {
-						info = 0;
-						(void)fprintf(stderr,
-						    "%s -> %s %3d%%\n",
-						    entp->fts_path, to.p_path,
-						    cp_pct(wtotal, fs->st_size));
-					}
-					if (wcount >= (ssize_t)wresid)
-						break;
-				}
-				if (wcount != (ssize_t)wresid) {
-					warn("%s", to.p_path);
-					rval = 1;
-					break;
+			while ((rcount = copy_file_range(from_fd, NULL,
+			    to_fd, NULL, bufsize, 0)) > 0)
+			{
+				wtotal += rcount;
+				if (info) {
+					info = 0;
+					(void)fprintf(stderr,
+					    "%s -> %s %3d%%\n",
+					    entp->fts_path, to.p_path,
+					    cp_pct(wtotal, fs->st_size));
 				}
 			}
 			if (rcount < 0) {