Am 30.11.2015 15:52, schrieb Ari Sundholm:
> From: Ari Sundholm <[email protected]>
>
> This applet discards blocks on a given device.
> Tested with multiple 32-bit and 64-bit kernel versions and two different SSDs.
>
> function old new delta
> blkdiscard_main - 300 +300
> .rodata 154690 154795 +105
> packed_usage 30275 30310 +35
> applet_names 2499 2510 +11
> applet_main 2904 2912 +8
> applet_nameofs 726 728 +2
> ------------------------------------------------------------------------------
> (add/remove: 2/0 grow/shrink: 5/0 up/down: 461/0) Total: 461 bytes
>
> v2: Use a common error message format string when !S_ISBLK() to save space.
>
> Signed-off-by: Ari Sundholm <[email protected]>
> ---
> util-linux/blkdiscard.c | 86
> +++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 86 insertions(+)
> create mode 100644 util-linux/blkdiscard.c
>
> diff --git a/util-linux/blkdiscard.c b/util-linux/blkdiscard.c
> new file mode 100644
> index 0000000..2694c11
> --- /dev/null
> +++ b/util-linux/blkdiscard.c
> @@ -0,0 +1,86 @@
> +/*
> + * Mini blkdiscard implementation for busybox
> + *
> + * Copyright (C) 2015 by Ari Sundholm <[email protected]> and Tuxera Inc.
> + *
> + * Licensed under GPLv2 or later, see file LICENSE in this source tree.
> + */
> +
> +//config:config BLKDISCARD
> +//config: bool "blkdiscard"
> +//config: default y
i never used/needed blkdiscard why do you set it to default y ? Is it part of
any
std. like POSIX or so ? (the man page did not mention it).
> +//config: help
> +//config: blkdiscard discards sectors on a given device.
> +
> +//kbuild:lib-$(CONFIG_BLKDISCARD) += blkdiscard.o
> +//applet:IF_BLKDISCARD(APPLET_NOFORK(blkdiscard, blkdiscard, BB_DIR_USR_BIN,
> BB_SUID_DROP, blkdiscard))
> +
> +//usage:#define blkdiscard_trivial_usage
> +//usage: "[-o offset] [-l length] [-s] device"
> +//usage:#define blkdiscard_full_usage "\n\n"
> +//usage: "Discard sectors on the given device\n"
> +//usage: "\n -o offset Byte offset into device (default: 0)"
> +//usage: "\n -l length Number of bytes to discard (default:
> size of device)"
> +//usage: "\n -s Perform a secure discard"
> +//usage:
> +//usage:#define blkdiscard_example_usage
> +//usage: "$ blkdiscard -o 0 -l 1G /dev/sdb"
> +
> +#include "libbb.h"
> +#include <linux/fs.h>
> +
> +/* This is a NOFORK applet. Be very careful! */
> +
> +int blkdiscard_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
> +int blkdiscard_main(int argc UNUSED_PARAM, char **argv)
> +{
> + unsigned opts;
> + uint64_t offset = 0;
> + char *offset_str;
> + uint64_t length;
> + char *length_str;
> + struct stat st;
> + int fd;
> + uint64_t range[2];
> +
> + enum {
> + OPT_OFFSET = (1 << 0),
> + OPT_LENGTH = (1 << 1),
> + OPT_SECURE = (1 << 2),
> + };
> +
> + opt_complementary = "=1";
> + opts = getopt32(argv, "o:l:s", &offset_str, &length_str);
> +
> + xstat(argv[optind], &st);
> + if (!S_ISBLK(st.st_mode))
> + bb_error_msg_and_die("%s: not a block device", argv[optind]);
> +
> + fd = xopen(argv[optind], O_RDWR|O_EXCL);
> +
> + if (opts & OPT_OFFSET)
> + offset = xatoull_sfx(offset_str, kMG_suffixes);
> +
> + if (opts & OPT_LENGTH)
> + length = xatoull_sfx(length_str, kMG_suffixes);
> + else {
> + ioctl_or_perror_and_die(fd, BLKGETSIZE64, &length,
> + "Failed to get device size");
> + length -= offset;
> + }
> +
> + range[0] = offset;
> + range[1] = length;
Can you discard offset, length ?
re,
wh
> + ioctl_or_perror_and_die(fd,
> + (opts & OPT_SECURE)
> + ? BLKSECDISCARD
> + : BLKDISCARD, &range,
> + "%s failed",
> + (opts & OPT_SECURE)
> + ? "BLKSECDISCARD"
> + : "BLKDISCARD");
> +
> + xclose(fd);
> +
> + return EXIT_SUCCESS;
> +}
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