From 34fed3ff1740aded9c2aae6b5d67a4eb696f738e Mon Sep 17 00:00:00 2001 From: Karel Zak Date: Thu, 9 Jan 2020 11:03:51 +0100 Subject: [PATCH] blkdiscard: use O_EXCL, add --force Let's make it more robust and safe. O_EXCL is an elegant way how to avoid unwanted discard on mounted device. Addresses: https://github.com/karelzak/util-linux/issues/915 Signed-off-by: Karel Zak Signed-off-by: Carlos Santos --- sys-utils/blkdiscard.8 | 5 +++++ sys-utils/blkdiscard.c | 11 ++++++++--- 2 files changed, 13 insertions(+), 3 deletions(-) diff --git a/sys-utils/blkdiscard.8 b/sys-utils/blkdiscard.8 index 1f3a32be9..98c6f36a9 100644 --- a/sys-utils/blkdiscard.8 +++ b/sys-utils/blkdiscard.8 @@ -36,6 +36,11 @@ MiB (=1024*1024), and so on for GiB, TiB, PiB, EiB, ZiB and YiB (the "iB" is optional, e.g., "K" has the same meaning as "KiB") or the suffixes KB (=1000), MB (=1000*1000), and so on for GB, TB, PB, EB, ZB and YB. .TP +.BR \-f , " \-\-force" +Disable all checking. Since v2.36 the block device is open in exclusive mode (O_EXCL) +by default to avoid collision with mounted filesystem or another kernel subsystem. +The force option disables the exclusive access mode. +.TP .BR \-o , " \-\-offset \fIoffset" Byte offset into the device from which to start discarding. The provided value will be aligned to the device sector size. The default value is zero. diff --git a/sys-utils/blkdiscard.c b/sys-utils/blkdiscard.c index f9ba5e468..589974f9c 100644 --- a/sys-utils/blkdiscard.c +++ b/sys-utils/blkdiscard.c @@ -88,6 +88,7 @@ static void __attribute__((__noreturn__)) usage(void) fputs(_("Discard the content of sectors on a device.\n"), out); fputs(USAGE_OPTIONS, out); + fputs(_(" -f, --force disable all checking\n"), out); fputs(_(" -o, --offset offset in bytes to discard from\n"), out); fputs(_(" -l, --length length of bytes to discard from the offset\n"), out); fputs(_(" -p, --step size of the discard iterations within the offset\n"), out); @@ -106,7 +107,7 @@ static void __attribute__((__noreturn__)) usage(void) int main(int argc, char **argv) { char *path; - int c, fd, verbose = 0, secsize; + int c, fd, verbose = 0, secsize, force = 0; uint64_t end, blksize, step, range[2], stats[2]; struct stat sb; struct timeval now, last; @@ -116,6 +117,7 @@ int main(int argc, char **argv) { "help", no_argument, NULL, 'h' }, { "version", no_argument, NULL, 'V' }, { "offset", required_argument, NULL, 'o' }, + { "force", no_argument, NULL, 'f' }, { "length", required_argument, NULL, 'l' }, { "step", required_argument, NULL, 'p' }, { "secure", no_argument, NULL, 's' }, @@ -133,8 +135,11 @@ int main(int argc, char **argv) range[1] = ULLONG_MAX; step = 0; - while ((c = getopt_long(argc, argv, "hVsvo:l:p:z", longopts, NULL)) != -1) { + while ((c = getopt_long(argc, argv, "hfVsvo:l:p:z", longopts, NULL)) != -1) { switch(c) { + case 'f': + force = 1; + break; case 'l': range[1] = strtosize_or_err(optarg, _("failed to parse length")); @@ -176,7 +181,7 @@ int main(int argc, char **argv) errtryhelp(EXIT_FAILURE); } - fd = open(path, O_WRONLY); + fd = open(path, O_WRONLY | (force ? 0 : O_EXCL)); if (fd < 0) err(EXIT_FAILURE, _("cannot open %s"), path); -- 2.18.2