From: Thomas Weißschuh <thomas@t-8ch.de>
Date: Sat, 1 Nov 2025 15:55:49 +0000 (+0100)
Subject: fallocate: require posix_fallocate() from libc
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=13b4a466cef2ff9176cb40eaaf0a82f42c1f0f71;p=thirdparty%2Futil-linux.git

fallocate: require posix_fallocate() from libc

Recent libcs implement posix_fallocate() properly. The fallback logic
should never be used. Furthermore unconditional support for
posix_fallocate() will enable some further cleanup and fixes.

Signed-off-by: Thomas Weißschuh <thomas@t-8ch.de>
---

diff --git a/configure.ac b/configure.ac
index fc66f2149..cf415f5ed 100644
--- a/configure.ac
+++ b/configure.ac
@@ -652,7 +652,6 @@ AC_CHECK_FUNCS([ \
 	pidfd_open \
 	pidfd_send_signal \
 	posix_fadvise \
-	posix_fallocate \
 	prctl \
 	qsort_r \
 	reallocarray \
@@ -693,6 +692,7 @@ AC_CHECK_FUNCS([inotify_init1], [have_inotify_init1=yes])
 AC_CHECK_FUNCS([ioperm iopl], [have_io=yes])
 AC_CHECK_FUNCS([openat fstatat unlinkat], [have_openat=yes], [have_openat=no])
 AC_CHECK_FUNCS([open_memstream], [have_open_memstream=yes],[have_open_memstream=no])
+AC_CHECK_FUNCS([posix_fallocate], [have_posix_fallocate=yes], [have_posix_fallocate=no])
 AC_CHECK_FUNCS([reboot], [have_reboot=yes],[have_reboot=no])
 AC_CHECK_FUNCS([updwtmpx updwtmpx], [have_gnu_utmpx=yes], [have_gnu_utmpx=no])
 
@@ -1590,6 +1590,7 @@ AC_ARG_ENABLE([fallocate],
 UL_BUILD_INIT([fallocate])
 UL_REQUIRES_LINUX([fallocate])
 UL_REQUIRES_HAVE([fallocate], [fallocate], [fallocate functions])
+UL_REQUIRES_HAVE([fallocate], [posix_fallocate], [posix_fallocate functions])
 AM_CONDITIONAL([BUILD_FALLOCATE], [test "x$build_fallocate" = xyes])
 
 
diff --git a/meson.build b/meson.build
index 9d5206154..cac8bb578 100644
--- a/meson.build
+++ b/meson.build
@@ -2044,6 +2044,7 @@ endif
 opt = get_option('build-fallocate') \
     .require(LINUX) \
     .require(conf.get('HAVE_FALLOCATE').to_string() == '1') \
+    .require(conf.get('HAVE_POSIX_FALLOCATE').to_string() == '1') \
     .allowed()
 exe = executable(
   'fallocate',
diff --git a/sys-utils/fallocate.c b/sys-utils/fallocate.c
index 244c1dfa4..aedb091cf 100644
--- a/sys-utils/fallocate.c
+++ b/sys-utils/fallocate.c
@@ -95,9 +95,7 @@ static void __attribute__((__noreturn__)) usage(void)
 	fputs(_(" -p, --punch-hole     replace a range with a hole (implies -n)\n"), out);
 	fputs(_(" -v, --verbose        verbose mode\n"), out);
 	fputs(_(" -w, --write-zeroes   write zeroes and ensure allocation of a range\n"), out);
-#ifdef HAVE_POSIX_FALLOCATE
 	fputs(_(" -x, --posix          use posix_fallocate(3) instead of fallocate(2)\n"), out);
-#endif
 	fputs(_(" -z, --zero-range     zero and ensure allocation of a range\n"), out);
 
 	fputs(USAGE_SEPARATOR, out);
@@ -138,7 +136,6 @@ static void xfallocate(int fd, int mode, off_t offset, off_t length)
 	}
 }
 
-#ifdef HAVE_POSIX_FALLOCATE
 static void xposix_fallocate(int fd, off_t offset, off_t length)
 {
 	errno = posix_fallocate(fd, offset, length);
@@ -146,7 +143,6 @@ static void xposix_fallocate(int fd, off_t offset, off_t length)
 		err(EXIT_FAILURE, _("fallocate failed"));
 	}
 }
-#endif
 
 /* The real buffer size has to be bufsize + sizeof(uintptr_t) */
 static int is_nul(void *buf, size_t bufsize)
@@ -287,9 +283,7 @@ int main(int argc, char **argv)
 	int	fd;
 	int	mode = 0;
 	int	dig = 0;
-#ifdef HAVE_POSIX_FALLOCATE
 	int	posix = 0;
-#endif
 	loff_t	length = -2LL;
 	loff_t	offset = 0;
 
@@ -356,12 +350,8 @@ int main(int argc, char **argv)
 			mode |= FALLOC_FL_WRITE_ZEROES;
 			break;
 		case 'x':
-#ifdef HAVE_POSIX_FALLOCATE
 			posix = 1;
 			break;
-#else
-			errx(EXIT_FAILURE, _("posix_fallocate support is not compiled"));
-#endif
 		case 'v':
 			verbose++;
 			break;
@@ -409,11 +399,9 @@ int main(int argc, char **argv)
 	if (dig)
 		dig_holes(fd, offset, length);
 	else {
-#ifdef HAVE_POSIX_FALLOCATE
 		if (posix)
 			xposix_fallocate(fd, offset, length);
 		else
-#endif
 			xfallocate(fd, mode, offset, length);
 
 		if (verbose) {