fsfreeze: new applet

NAME
       fsfreeze - suspend access to a filesystem (Ext3/4, ReiserFS, JFS, XFS)
SYNOPSIS
       fsfreeze --freeze|--unfreeze mountpoint
DESCRIPTION
       fsfreeze suspends or resumes access to a filesystem.
       fsfreeze halts any new access to the filesystem and creates a stable
       image on disk.
AVAILABILITY
       The fsfreeze command is part of the util-linux 2.28

function                                             old     new   delta
fsfreeze_main                                          -      81     +81
applet_names                                        2597    2606      +9
applet_main                                         1504    1508      +4
applet_suid                                           94      95      +1
applet_install_loc                                   188     189      +1

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

diff --git a/util-linux/fsfreeze.c b/util-linux/fsfreeze.c
new file mode 100644 (file)
index 0000000..fb1ebdc
--- /dev/null
+++ b/util-linux/fsfreeze.c
@@ -0,0 +1,54 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * Copyright (C) 2017 Denys Vlasenko <vda.linux@googlemail.com>
+ *
+ * Licensed under GPLv2, see file LICENSE in this source tree.
+ */
+
+//config:config FSFREEZE
+//config:      bool "fsfreeze"
+//config:      default y
+//config:      select PLATFORM_LINUX
+//config:      select LONG_OPTS
+//config:      help
+//config:        Halt new accesses and flush writes on a mounted filesystem.
+
+//applet:IF_FSFREEZE(APPLET(fsfreeze, BB_DIR_SBIN, BB_SUID_DROP))
+
+//kbuild:lib-$(CONFIG_FSFREEZE) += fsfreeze.o
+
+//usage:#define fsfreeze_trivial_usage
+//usage:       "--[un]freeze MOUNTPOINT"
+//usage:#define fsfreeze_full_usage "\n\n"
+//usage:       "Flush and halt writes to MOUNTPOINT"
+
+#include "libbb.h"
+#include <linux/fs.h>
+
+#ifndef FIFREEZE
+# define FIFREEZE _IOWR('X', 119, int)
+# define FITHAW   _IOWR('X', 120, int)
+#endif
+
+int fsfreeze_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int fsfreeze_main(int argc UNUSED_PARAM, char **argv)
+{
+       unsigned opts;
+       int fd;
+
+       applet_long_options =
+               "freeze\0"   No_argument "\xff"
+               "unfreeze\0" No_argument "\xfe"
+       ;
+       /* exactly one non-option arg: the mountpoint */
+       /* one of opts is required */
+       /* opts are mutually exclusive */
+       opt_complementary = "=1:""\xff:\xfe:""\xff--\xfe:\xfe--\xff";
+       opts = getopt32(argv, "");
+
+       fd = xopen(argv[optind], O_RDONLY);
+       /* Works with NULL arg on linux-4.8.0 */
+       xioctl(fd, (opts & 1) ? FIFREEZE : FITHAW, NULL);
+
+       return EXIT_SUCCESS;
+}