busybox/util-linux/fstrim.c

/* vi: set sw=4 ts=4: */
/*
 * fstrim.c - discard the part (or whole) of mounted filesystem.
 *
 * 03 March 2012 - Malek Degachi <malek-degachi@laposte.net>
 * Adapted for busybox from util-linux-2.12a.
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */
//config:config FSTRIM
//config:	bool "fstrim (4.6 kb)"
//config:	default y
//config:	help
//config:	Discard unused blocks on a mounted filesystem.

//applet:IF_FSTRIM(APPLET_NOEXEC(fstrim, fstrim, BB_DIR_SBIN, BB_SUID_DROP, fstrim))

//kbuild:lib-$(CONFIG_FSTRIM) += fstrim.o

//usage:#define fstrim_trivial_usage
//usage:       "[OPTIONS] MOUNTPOINT"
//usage:#define fstrim_full_usage "\n\n"
//usage:       "	-o OFFSET	Offset in bytes to discard from"
//usage:     "\n	-l LEN		Bytes to discard"
//usage:     "\n	-m MIN		Minimum extent length"
//usage:     "\n	-v		Print number of discarded bytes"

#include "libbb.h"
#include <linux/fs.h>

#ifndef FITRIM
struct fstrim_range {
	uint64_t start;
	uint64_t len;
	uint64_t minlen;
};
#define FITRIM		_IOWR('X', 121, struct fstrim_range)
#endif

int fstrim_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int fstrim_main(int argc UNUSED_PARAM, char **argv)
{
	struct fstrim_range range;
	char *arg_o, *arg_l, *arg_m, *mp;
	unsigned opts;
	int fd;

	enum {
		OPT_o = (1 << 0),
		OPT_l = (1 << 1),
		OPT_m = (1 << 2),
		OPT_v = (1 << 3),
	};

#if ENABLE_LONG_OPTS
	static const char fstrim_longopts[] ALIGN1 =
		"offset\0"    Required_argument    "o"
		"length\0"    Required_argument    "l"
		"minimum\0"   Required_argument    "m"
		"verbose\0"   No_argument          "v"
		;
#endif

	opts = getopt32long(argv, "^"
			"o:l:m:v"
			"\0" "=1", fstrim_longopts,
			&arg_o, &arg_l, &arg_m
	);

	memset(&range, 0, sizeof(range));
	range.len = ULLONG_MAX;

	if (opts & OPT_o)
		range.start = xatoull_sfx(arg_o, kmg_i_suffixes);
	if (opts & OPT_l)
		range.len = xatoull_sfx(arg_l, kmg_i_suffixes);
	if (opts & OPT_m)
		range.minlen = xatoull_sfx(arg_m, kmg_i_suffixes);

	mp = argv[optind];
//Wwhy bother checking that it's a blockdev?
//	if (find_block_device(mp)) {
		fd = xopen_nonblocking(mp);

		/* On ENOTTY error, util-linux 2.31 says:
		 * "fstrim: FILE: the discard operation is not supported"
		 */
		xioctl(fd, FITRIM, &range);

		if (ENABLE_FEATURE_CLEAN_UP)
			close(fd);

		if (opts & OPT_v)
			printf("%s: %llu bytes trimmed\n", mp, (unsigned long long)range.len);
		return EXIT_SUCCESS;
//	}
	return EXIT_FAILURE;
}