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mkswap: add --lock and LOCK_BLOCK_DEVICE 

Addresses: https://github.com/karelzak/util-linux/issues/921
Signed-off-by: Karel Zak <kzak@redhat.com>
This commit is contained in:
Karel Zak 2020-05-27 16:58:08 +02:00
parent ec8f712157
commit b8671fe763
2 changed files with 30 additions and 0 deletions
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10
disk-utils/mkswap.8
View File

@ -76,6 +76,14 @@ Specify a \fIlabel\fR for the device, to allow
.B swapon
by label.
.TP
\fB\-\-lock\fR[=\fImode\fR]
Use exclusive BSD lock for device or file it operates. The optional argument
\fImode\fP can be \fByes\fR, \fBno\fR (or 1 and 0) or \fBnonblock\fR. If the \fImode\fR
argument is omitted, it defaults to \fB"yes"\fR. This option overwrites
environment variable \fB$LOCK_BLOCK_DEVICE\fR. The default is not to use any
lock at all, but it's recommended to avoid collisions with udevd or other
tools.
.TP
.BR \-p , " \-\-pagesize " \fIsize\fR
Specify the page \fIsize\fR (in bytes) to use. This option is usually unnecessary;
.B mkswap
@ -102,6 +110,8 @@ Display version information and exit.
.SH ENVIRONMENT
.IP LIBBLKID_DEBUG=all
enables libblkid debug output.
.IP LOCK_BLOCK_DEVICE=<mode>
use exclusive BSD lock. The mode is "1" or "0". See \fB\-\-lock\fR for more details.
.SH NOTES
The maximum useful size of a swap area depends on the architecture and

20
disk-utils/mkswap.c
View File

@ -53,6 +53,7 @@ struct mkswap_control {
void *signature_page;/* buffer with swap header */
char *devname; /* device or file name */
const char *lockmode; /* as specified by --lock */
struct stat devstat; /* stat() result */
int fd; /* swap file descriptor */
@ -161,6 +162,8 @@ static void __attribute__((__noreturn__)) usage(void)
" -v, --swapversion NUM specify swap-space version number\n"
" -U, --uuid UUID specify the uuid to use\n"
));
fprintf(out,
_(" --lock[=<mode>] use exclusive device lock (%s, %s or %s)\n"), "yes", "no", "nonblock");
printf(USAGE_HELP_OPTIONS(27));
printf(USAGE_MAN_TAIL("mkswap(8)"));
@ -244,6 +247,10 @@ static void open_device(struct mkswap_control *ctl)
ctl->fd = open_blkdev_or_file(&ctl->devstat, ctl->devname, O_RDWR);
if (ctl->fd < 0)
err(EXIT_FAILURE, _("cannot open %s"), ctl->devname);
if (blkdev_lock(ctl->fd, ctl->devname, ctl->lockmode) != 0)
exit(EXIT_FAILURE);
if (ctl->check && S_ISREG(ctl->devstat.st_mode)) {
ctl->check = 0;
warnx(_("warning: checking bad blocks from swap file is not supported: %s"),
@ -354,6 +361,9 @@ int main(int argc, char **argv)
const char *opt_uuid = NULL;
uuid_t uuid_dat;
#endif
enum {
OPT_LOCK = CHAR_MAX + 1,
};
static const struct option longopts[] = {
{ "check", no_argument, NULL, 'c' },
{ "force", no_argument, NULL, 'f' },
@ -363,6 +373,7 @@ int main(int argc, char **argv)
{ "uuid", required_argument, NULL, 'U' },
{ "version", no_argument, NULL, 'V' },
{ "help", no_argument, NULL, 'h' },
{ "lock", optional_argument, NULL, OPT_LOCK },
{ NULL, 0, NULL, 0 }
};
@ -401,6 +412,15 @@ int main(int argc, char **argv)
break;
case 'V':
print_version(EXIT_SUCCESS);
break;
case OPT_LOCK:
ctl.lockmode = "1";
if (optarg) {
if (*optarg == '=')
optarg++;
ctl.lockmode = optarg;
}
break;
case 'h':
usage();
default: