--- /dev/null
+.\" -*- nroff -*-
+.TH FALLOCATE 1 "Jul 2009" "Version 1.0"
+.SH NAME
+fallocate \- preallocate space to a file.
+.SH SYNOPSIS
+.B fallocate
+.RB [ \-n ]
+.RB [ \-o
+.IR offset ]
+.B \-l
+.IR length
+.I filename
+.SH DESCRIPTION
+.B fallocate
+is used to preallocate blocks to a file. For filesystems which support the
+fallocate system call, this is done quickly by allocating blocks and marking
+them as uninitialized, requiring no IO to the data blocks. This is much faster
+than creating a file by filling it with zeros.
+.PP
+As of the Linux Kernel v2.6.31, the fallocate system call is supported by the
+btrfs, ext4, ocfs2, and xfs filesystems.
+.PP
+The exit code returned by
+.B fallocate
+is 0 on success and 1 on failure.
+.PP
+.SH OPTIONS
+.IP "\fB\-h, \-\-help\fP"
+Print help and exit.
+.IP "\fB\-n, \-\-keep-size\fP"
+Do not modify the apparent length of the file. This may effectively allocate
+blocks past EOF, which can be removed with a truncate.
+.IP "\fB\-o, \-\-offset\fP \fIoffset\fP
+Specifies the beginning offset of the allocation, in bytes. Suffixes of k, m,
+g, t, p, e may be specified to denote KiB, MiB, GiB, etc.
+.IP "\fB\-l, \-\-length\fP \fIlength\fP
+Specifies the length of the allocation, in bytes. Suffixes of k, m, g, t, p, e
+may be specified to denote KiB, MiB, GiB, etc.
+.SH AUTHORS
+.nf
+Eric Sandeen <sandeen@redhat.com>
+Karel Zak <kzak@redhat.com>
+.fi
+.SH SEE ALSO
+.BR fallocate (2),
+.BR posix_fallocate (3),
+.BR truncate (1)
+.SH AVAILABILITY
+The fallocate command is part of the util-linux-ng package and is available from
+ftp://ftp.kernel.org/pub/linux/utils/util-linux-ng/.
+
--- /dev/null
+/*
+ * fallocate - utility to use the fallocate system call
+ *
+ * Copyright (C) 2008-2009 Red Hat, Inc. All rights reserved.
+ * Written by Eric Sandeen <sandeen@redhat.com>
+ * Karel Zak <kzak@redhat.com>
+ *
+ * cvtnum routine taken from xfsprogs,
+ * Copyright (c) 2003-2005 Silicon Graphics, 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.
+ *
+ * This program is distributed in the hope that it would 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, write to the Free Software Foundation,
+ * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <ctype.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <getopt.h>
+#include <err.h>
+
+#ifndef HAVE_FALLOCATE
+# include <sys/syscall.h>
+#endif
+
+#include <linux/falloc.h> /* for FALLOC_FL_* flags */
+
+#include "nls.h"
+
+
+static void __attribute__((__noreturn__)) usage(FILE *out)
+{
+ fprintf(out, _("Usage: %s [options] <filename>\n\nOptions:\n"),
+ program_invocation_short_name);
+
+ fprintf(out, _(
+ " -h, --help this help\n"
+ " -n, --keep-size don't modify the length of the file\n"
+ " -o, --offset <num> offset of the allocation, in bytes\n"
+ " -l, --length <num> length of the allocation, in bytes\n"));
+
+ fprintf(out, _("\nFor more information see fallocate(1).\n"));
+
+ exit(out == stderr ? EXIT_FAILURE : EXIT_SUCCESS);
+}
+
+#define EXABYTES(x) ((x) << 60)
+#define PETABYTES(x) ((x) << 50)
+#define TERABYTES(x) ((x) << 40)
+#define GIGABYTES(x) ((x) << 30)
+#define MEGABYTES(x) ((x) << 20)
+#define KILOBYTES(x) ((x) << 10)
+
+static loff_t cvtnum(char *s)
+{
+ loff_t i;
+ char *sp;
+
+ i = strtoll(s, &sp, 0);
+ if (i == 0 && sp == s)
+ return -1LL;
+ if (*sp == '\0')
+ return i;
+ if (sp[1] != '\0')
+ return -1LL;
+
+ switch (tolower(*sp)) {
+ case 'k':
+ return KILOBYTES(i);
+ case 'm':
+ return MEGABYTES(i);
+ case 'g':
+ return GIGABYTES(i);
+ case 't':
+ return TERABYTES(i);
+ case 'p':
+ return PETABYTES(i);
+ case 'e':
+ return EXABYTES(i);
+ }
+
+ return -1LL;
+}
+
+int main(int argc, char **argv)
+{
+ char *fname;
+ int c;
+ int error;
+ int fd;
+ int mode = 0;
+ loff_t length = -2LL;
+ loff_t offset = 0;
+
+ struct option longopts[] = {
+ { "help", 0, 0, 'h' },
+ { "keep-size", 0, 0, 'n' },
+ { "offset", 1, 0, 'o' },
+ { "lenght", 1, 0, 'l' },
+ { NULL, 0, 0, 0 }
+ };
+
+ setlocale(LC_ALL, "");
+ bindtextdomain(PACKAGE, LOCALEDIR);
+ textdomain(PACKAGE);
+
+ while ((c = getopt_long(argc, argv, "hnl:o:", longopts, NULL)) != -1) {
+ switch(c) {
+ case 'h':
+ usage(stdout);
+ break;
+ case 'n':
+ mode |= FALLOC_FL_KEEP_SIZE;
+ break;
+ case 'l':
+ length = cvtnum(optarg);
+ break;
+ case 'o':
+ offset = cvtnum(optarg);
+ break;
+ default:
+ usage(stderr);
+ break;
+ }
+ }
+
+ if (length == -2LL)
+ errx(EXIT_FAILURE, _("no length argument specified"));
+ if (length <= 0)
+ errx(EXIT_FAILURE, _("invalid length value specified"));
+ if (offset < 0)
+ errx(EXIT_FAILURE, _("invalid offset value specified"));
+ if (optind == argc)
+ errx(EXIT_FAILURE, _("no filename specified."));
+
+ fname = argv[optind++];
+
+ fd = open(fname, O_WRONLY|O_CREAT, 0644);
+ if (fd < 0)
+ err(EXIT_FAILURE, _("%s: open failed"), fname);
+
+#ifdef HAVE_FALLOCATE
+ error = fallocate(fd, mode, offset, length);
+#else
+ error = syscall(SYS_fallocate, fd, mode, offset, length);
+#endif
+ /*
+ * EOPNOTSUPP: The FALLOC_FL_KEEP_SIZE is unsupported
+ * ENOSYS: The filesystem does not support sys_fallocate
+ */
+ if (error < 0) {
+ if ((mode & FALLOC_FL_KEEP_SIZE) && errno == EOPNOTSUPP)
+ errx(EXIT_FAILURE,
+ _("keep size mode (-n option) unsupported"));
+ err(EXIT_FAILURE, _("%s: fallocate failed"), fname);
+ }
+
+ close(fd);
+ return EXIT_SUCCESS;
+}
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