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cp: use copy_file_range(2)

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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
This commit is contained in:
Alan Somers 2020-09-10 02:48:55 +00:00
parent 5c74d551d2
commit c01816a97f
1 changed files with 10 additions and 21 deletions
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19
bin/cp/utils.c
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@ -212,13 +212,10 @@ 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;
while ((rcount = copy_file_range(from_fd, NULL,
to_fd, NULL, bufsize, 0)) > 0)
{
wtotal += rcount;
if (info) {
info = 0;
(void)fprintf(stderr,
@ -226,14 +223,6 @@ copy_file(const FTSENT *entp, int dne)
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;
}
}
if (rcount < 0) {
warn("%s", entp->fts_path);