On Mon, 2015-11-30 at 15:14 +0000, walter harms wrote:
>
> 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).
>
Just an oversight, partly caused by the fact that the applet is useful
to myself. Indeed, most people may not need it.
blkdiscard has been part of util-linux since 2012, IIRC, but I do not
know if it is part of any standard per se.
> > +//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 ?
>
Sure, I'll check if that shrinks the applet down a bit.
Best regards,
Ari Sundholm
[email protected]
> 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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