thirdparty/util-linux
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losetup: support ioctl cmd of LOOP_SET_DIRECT_IO

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From v4.4, linux kernel starts to support direct I/O and
AIO to backing file for loop driver, so allow losetup to
enable the feature by using LOOP_SET_DIRECT_IO ioctl cmd.

Signed-off-by: Ming Lei <tom.leiming@gmail.com>
This commit is contained in:
Ming Lei 2015-11-17 22:32:47 +08:00 • committed by Karel Zak
parent 710dd49239
commit 64c3bb3cb7
3 changed files with 45 additions and 2 deletions
Download patch file Download diff file Expand all files Collapse all files

2
include/loopdev.h
View file

@ -23,6 +23,7 @@
#define LOOP_GET_STATUS64 0x4C05
/* #define LOOP_CHANGE_FD 0x4C06 */
#define LOOP_SET_CAPACITY 0x4C07
#define LOOP_SET_DIRECT_IO 0x4C08
/* /dev/loop-control interface */
#ifndef LOOP_CTL_ADD
@ -164,6 +165,7 @@ extern int loopcxt_next(struct loopdev_cxt *lc);
extern int loopcxt_setup_device(struct loopdev_cxt *lc);
extern int loopcxt_delete_device(struct loopdev_cxt *lc);
extern int loopcxt_set_capacity(struct loopdev_cxt *lc);
extern int loopcxt_set_dio(struct loopdev_cxt *lc, unsigned long use_dio);
int loopcxt_set_offset(struct loopdev_cxt *lc, uint64_t offset);
int loopcxt_set_sizelimit(struct loopdev_cxt *lc, uint64_t sizelimit);

18
lib/loopdev.c
View file

@ -1315,6 +1315,24 @@ int loopcxt_set_capacity(struct loopdev_cxt *lc)
return 0;
}
int loopcxt_set_dio(struct loopdev_cxt *lc, unsigned long use_dio)
{
int fd = loopcxt_get_fd(lc);
if (fd < 0)
return -EINVAL;
/* Kernels prior to v4.4 don't support this ioctl */
if (ioctl(fd, LOOP_SET_DIRECT_IO, use_dio) < 0) {
int rc = -errno;
DBG(CXT, ul_debugobj(lc, "LOOP_SET_DIRECT_IO failed: %m"));
return rc;
}
DBG(CXT, ul_debugobj(lc, "direct io set"));
return 0;
}
int loopcxt_delete_device(struct loopdev_cxt *lc)
{
int fd = loopcxt_get_fd(lc);

25
sys-utils/losetup.c
View file

@ -35,6 +35,7 @@ enum {
A_SHOW_ONE, /* print info about one device */
A_FIND_FREE, /* find first unused */
A_SET_CAPACITY, /* set device capacity */
A_SET_DIRECT_IO, /* set accessing backing file by direct io */
};
enum {
@ -393,6 +394,7 @@ static void usage(FILE *out)
fputs(_(" --sizelimit <num> device is limited to <num> bytes of the file\n"), out);
fputs(_(" -P, --partscan create a partitioned loop device\n"), out);
fputs(_(" -r, --read-only set up a read-only loop device\n"), out);
fputs(_(" --direct-io open backing file with O_DIRECT\n"), out);
fputs(_(" --show print device name after setup (with -f)\n"), out);
fputs(_(" -v, --verbose verbose mode\n"), out);
@ -446,11 +448,13 @@ int main(int argc, char **argv)
int res = 0, showdev = 0, lo_flags = 0;
char *outarg = NULL;
int list = 0;
unsigned long use_dio = 0, set_dio = 0;
enum {
OPT_SIZELIMIT = CHAR_MAX + 1,
OPT_SHOW,
OPT_RAW
OPT_RAW,
OPT_DIO
};
static const struct option longopts[] = {
{ "all", 0, 0, 'a' },
@ -468,6 +472,7 @@ int main(int argc, char **argv)
{ "sizelimit", 1, 0, OPT_SIZELIMIT },
{ "partscan", 0, 0, 'P' },
{ "read-only", 0, 0, 'r' },
{ "direct-io", 1, 0, OPT_DIO },
{ "raw", 0, 0, OPT_RAW },
{ "show", 0, 0, OPT_SHOW },
{ "verbose", 0, 0, 'v' },
@ -557,6 +562,10 @@ int main(int argc, char **argv)
case OPT_SHOW:
showdev = 1;
break;
case OPT_DIO:
set_dio = 1;
use_dio = strtoul_or_err(optarg, _("failed to parse dio"));
break;
case 'v':
break;
case 'V':
@ -609,8 +618,13 @@ int main(int argc, char **argv)
if (!act && optind + 1 == argc) {
/*
* losetup [--list] <device>
* OR
* losetup --direct-io DIO <device>
*/
if (!set_dio)
act = A_SHOW_ONE;
else
act = A_SET_DIRECT_IO;
if (!is_loopdev(argv[optind]) ||
loopcxt_set_device(&lc, argv[optind]))
err(EXIT_FAILURE, _("%s: failed to use device"),
@ -695,6 +709,8 @@ int main(int argc, char **argv)
if (showdev)
printf("%s\n", loopcxt_get_device(&lc));
warn_size(file, sizelimit);
if (set_dio)
goto lo_set_dio;
}
break;
}
@ -747,6 +763,13 @@ int main(int argc, char **argv)
warn(_("%s: set capacity failed"),
loopcxt_get_device(&lc));
break;
case A_SET_DIRECT_IO:
lo_set_dio:
res = loopcxt_set_dio(&lc, use_dio);
if (res)
warn(_("%s: set direct io failed"),
loopcxt_get_device(&lc));
break;
default:
usage(stderr);
break;