Commit 486a81f3 authored by Paul Eggert's avatar Paul Eggert

Use copy_file_range to copy files

The copy_file_range syscall (introduced in Linux kernel
version 4.5) can copy files more efficiently via server-side
copy etc.
* admin/merge-gnulib (GNULIB_MODULES): Add copy-file-range.
* lib/copy-file-range.c, m4/copy-file-range.m4:
New files, copied from Gnulib.
* lib/gnulib.mk.in, m4/gnulib-comp.m4: Regenerate.
* src/fileio.c (Fcopy_file): Try copy_file_range first,
falling back on read+write only if copy_file_range failed or
if the input is empty and so could be a /proc file.
parent 111408a0
......@@ -27,7 +27,7 @@ GNULIB_URL=git://git.savannah.gnu.org/gnulib.git
GNULIB_MODULES='
alloca-opt binary-io byteswap c-ctype c-strcase
careadlinkat close-stream
careadlinkat close-stream copy-file-range
count-leading-zeros count-one-bits count-trailing-zeros
crypto/md5-buffer crypto/sha1-buffer crypto/sha256-buffer crypto/sha512-buffer
d-type diffseq dosname dtoastr dtotimespec dup2
......
/* Stub for copy_file_range
Copyright 2019 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
#include <config.h>
#include <unistd.h>
#include <errno.h>
ssize_t
copy_file_range (int infd, off_t *pinoff,
int outfd, off_t *poutoff,
size_t length, unsigned int flags)
{
/* There is little need to emulate copy_file_range with read+write,
since programs that use copy_file_range must fall back on
read+write anyway. */
errno = ENOSYS;
return -1;
}
......@@ -74,6 +74,7 @@
# c-strcase \
# careadlinkat \
# close-stream \
# copy-file-range \
# count-leading-zeros \
# count-one-bits \
# count-trailing-zeros \
......@@ -1274,6 +1275,17 @@ EXTRA_DIST += close-stream.h
endif
## end gnulib module close-stream
## begin gnulib module copy-file-range
ifeq (,$(OMIT_GNULIB_MODULE_copy-file-range))
EXTRA_DIST += copy-file-range.c
EXTRA_libgnu_a_SOURCES += copy-file-range.c
endif
## end gnulib module copy-file-range
## begin gnulib module count-leading-zeros
ifeq (,$(OMIT_GNULIB_MODULE_count-leading-zeros))
......
# copy-file-range.m4
dnl Copyright 2019 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.
AC_DEFUN([gl_FUNC_COPY_FILE_RANGE],
[
AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
dnl Persuade glibc <unistd.h> to declare copy_file_range.
AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
dnl Use AC_LINK_IFELSE, rather than AC_CHECK_FUNCS or a variant,
dnl since we don't want AC_CHECK_FUNCS's checks for glibc stubs.
dnl Programs that use copy_file_range must fall back on read+write
dnl anyway, and there's little point to substituting the Gnulib stub
dnl for a glibc stub.
AC_CACHE_CHECK([for copy_file_range], [gl_cv_func_copy_file_range],
[AC_LINK_IFELSE(
[AC_LANG_PROGRAM(
[[#include <unistd.h>
]],
[[ssize_t (*func) (int, off_t *, int, off_t, size_t, unsigned)
= copy_file_range;
return func (0, 0, 0, 0, 0, 0) & 127;
]])
],
[gl_cv_func_copy_file_range=yes],
[gl_cv_func_copy_file_range=no])
])
if test "$gl_cv_func_copy_file_range" != yes; then
HAVE_COPY_FILE_RANGE=0
fi
])
......@@ -56,6 +56,7 @@ AC_DEFUN([gl_EARLY],
# Code from module clock-time:
# Code from module cloexec:
# Code from module close-stream:
# Code from module copy-file-range:
# Code from module count-leading-zeros:
# Code from module count-one-bits:
# Code from module count-trailing-zeros:
......@@ -201,6 +202,11 @@ AC_DEFUN([gl_INIT],
AC_CHECK_FUNCS_ONCE([readlinkat])
gl_CLOCK_TIME
gl_MODULE_INDICATOR([close-stream])
gl_FUNC_COPY_FILE_RANGE
if test $HAVE_COPY_FILE_RANGE = 0; then
AC_LIBOBJ([copy-file-range])
fi
gl_UNISTD_MODULE_INDICATOR([copy-file-range])
gl_COUNT_LEADING_ZEROS
gl_COUNT_ONE_BITS
gl_COUNT_TRAILING_ZEROS
......@@ -846,6 +852,7 @@ AC_DEFUN([gl_FILE_LIST], [
lib/cloexec.h
lib/close-stream.c
lib/close-stream.h
lib/copy-file-range.c
lib/count-leading-zeros.c
lib/count-leading-zeros.h
lib/count-one-bits.c
......@@ -995,6 +1002,7 @@ AC_DEFUN([gl_FILE_LIST], [
m4/builtin-expect.m4
m4/byteswap.m4
m4/clock_time.m4
m4/copy-file-range.m4
m4/count-leading-zeros.m4
m4/count-one-bits.m4
m4/count-trailing-zeros.m4
......
......@@ -2117,14 +2117,39 @@ permissions. */)
newsize = st.st_size;
else
{
char buf[MAX_ALLOCA];
ptrdiff_t n;
for (newsize = 0; 0 < (n = emacs_read_quit (ifd, buf, sizeof buf));
newsize += n)
if (emacs_write_quit (ofd, buf, n) != n)
report_file_error ("Write error", newname);
if (n < 0)
report_file_error ("Read error", file);
off_t insize = st.st_size;
ssize_t copied;
for (newsize = 0; newsize < insize; newsize += copied)
{
/* Copy at most COPY_MAX bytes at a time; this is min
(PTRDIFF_MAX, SIZE_MAX) truncated to a value that is
surely aligned well. */
ptrdiff_t copy_max = min (PTRDIFF_MAX, SIZE_MAX) >> 30 << 30;
off_t intail = insize - newsize;
ptrdiff_t len = min (intail, copy_max);
copied = copy_file_range (ifd, NULL, ofd, NULL, len, 0);
if (copied <= 0)
break;
maybe_quit ();
}
/* Fall back on read+write if copy_file_range failed, or if the
input is empty and so could be a /proc file. read+write will
either succeed, or report an error more precisely than
copy_file_range would. */
if (newsize != insize || insize == 0)
{
char buf[MAX_ALLOCA];
for (; (copied = emacs_read_quit (ifd, buf, sizeof buf));
newsize += copied)
{
if (copied < 0)
report_file_error ("Read error", file);
if (emacs_write_quit (ofd, buf, copied) != copied)
report_file_error ("Write error", newname);
}
}
}
/* Truncate any existing output file after writing the data. This
......
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