fallocate: Added posix_fallocate() support.

No all filesystems support Linux fallocate. The new option allow use
posix implementation if necessary.

Signed-off-by: Karel Zak <kzak@redhat.com>

AUTHORS

@@ -186,6 +186,7 @@ CONTRIBUTORS:
       David Shea <dshea@redhat.com>
       David Woodhouse <dwmw2@infradead.org>
       Deiz <silverwraithii@gmail.com>
+      Denis Chaplygin <dchaplyg@redhat.com>
       Denis ChengRq <crquan@gmail.com>
       Dennis Gilmore <dennis@ausil.us>
       Dennis H Jensen <dennis.h.jensen@siemens.com>

configure.ac

@@ -1195,6 +1195,34 @@ AS_IF([test "x$build_fallocate" = xyes], [
   AC_MSG_RESULT([no])])
 ])
 
+AS_IF([test "x$build_fallocate" = xyes], [
+  dnl check for valid posix_fallocate() function
+  AC_MSG_CHECKING([for valid posix_fallocate() function])
+  AC_LINK_IFELSE([AC_LANG_PROGRAM([[
+#ifdef HAVE_UNISTD_H
+# include <unistd.h>
+#endif
+#ifdef HAVE_SYS_TYPES_H
+# include <sys/types.h>
+#endif
+#ifdef HAVE_LINUX_FALLOC_H
+# include <linux/falloc.h>
+#endif
+#ifdef HAVE_FCNTL_H
+# include <fcntl.h>
+#endif
+]],[[
+   long ret;
+   ret = posix_fallocate(0, 0xfffffffful, 0xfffffffful);
+   if (ret != 0) {
+      return 1;
+   }
+   ]])],[
+  AC_MSG_RESULT([yes])
+  AC_DEFINE([HAVE_POSIX_FALLOCATE], [1], [Have valid posix_fallocate() function])],[
+  AC_MSG_RESULT([no])])
+])
+
 
 AC_ARG_ENABLE([unshare],
   AS_HELP_STRING([--disable-unshare], [do not build unshare]),

sys-utils/fallocate.1

@@ -17,6 +17,13 @@ fallocate \- preallocate or deallocate space to a file
 .RB [ \-l
 .IR length ]
 .I filename
+.PP
+.B fallocate \-x
+.RB [ \-o
+.IR offset ]
+.RB \-l
+.IR length
+.I filename
 .SH DESCRIPTION
 .B fallocate
 is used to manipulate the allocated disk space for a file, either to deallocate
@@ -88,6 +95,10 @@ Btrfs (since Linux 3.7) and tmpfs (since Linux 3.5).
 .BR \-v , " \-\-verbose"
 Enable verbose mode.
 .TP
+.BR \-x , " \-\-posix"
+Enable POSIX operation mode. In that mode allocation operation always completes,
+but it may take longer time when fast allocation is not supported by the underlying filesystem.
+.TP
 .BR \-z , " \-\-zero\-range"
 Zeroes space in the byte range starting at \fIoffset\fP and
 continuing for \fIlength\fR bytes.  Within the specified range, blocks are

sys-utils/fallocate.c

@@ -94,6 +94,9 @@ static void __attribute__((__noreturn__)) usage(FILE *out)
 	fputs(_(" -o, --offset <num>   offset for range operations, in bytes\n"), out);
 	fputs(_(" -p, --punch-hole     replace a range with a hole (implies -n)\n"), out);
 	fputs(_(" -z, --zero-range     zero 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(_(" -v, --verbose        verbose mode\n"), out);
 
 	fputs(USAGE_SEPARATOR, out);
@@ -134,6 +137,15 @@ 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)
+{
+	int error = posix_fallocate(fd, offset, length);
+	if (error < 0) {
+		err(EXIT_FAILURE, _("fallocate failed"));
+	}
+}
+#endif
 
 static int skip_hole(int fd, off_t *off)
 {
@@ -277,6 +289,7 @@ int main(int argc, char **argv)
 	int	fd;
 	int	mode = 0;
 	int	dig = 0;
+	int posix = 0;
 	loff_t	length = -2LL;
 	loff_t	offset = 0;
 
@@ -291,6 +304,7 @@ int main(int argc, char **argv)
 	    { "zero-range",     0, 0, 'z' },
 	    { "offset",         1, 0, 'o' },
 	    { "length",         1, 0, 'l' },
+	    { "posix",          0, 0, 'x' },
 	    { "verbose",        0, 0, 'v' },
 	    { NULL,             0, 0, 0 }
 	};
@@ -298,6 +312,7 @@ int main(int argc, char **argv)
 	static const ul_excl_t excl[] = {	/* rows and cols in in ASCII order */
 		{ 'c', 'd', 'p', 'z' },
 		{ 'c', 'n' },
+		{ 'x', 'c', 'd', 'i', 'n', 'p', 'z'},
 		{ 0 }
 	};
 	int excl_st[ARRAY_SIZE(excl)] = UL_EXCL_STATUS_INIT;
@@ -307,7 +322,7 @@ int main(int argc, char **argv)
 	textdomain(PACKAGE);
 	atexit(close_stdout);
 
-	while ((c = getopt_long(argc, argv, "hvVncpdizl:o:", longopts, NULL))
+	while ((c = getopt_long(argc, argv, "hvVncpdizxl:o:", longopts, NULL))
 			!= -1) {
 
 		err_exclusive_options(c, longopts, excl, excl_st);
@@ -340,6 +355,13 @@ int main(int argc, char **argv)
 		case 'z':
 			mode |= FALLOC_FL_ZERO_RANGE;
 			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;
@@ -384,6 +406,10 @@ int main(int argc, char **argv)
 
 	if (dig)
 		dig_holes(fd, offset, length);
+#ifdef HAVE_POSIX_FALLOCATE
+	else if (posix)
+		xposix_fallocate(fd, offset, length);
+#endif
 	else
 		xfallocate(fd, mode, offset, length);