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Add support for using thin provisioned lvm volumes when creating a container. #67

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Add support for using thin provisioned lvm volumes when creating a container. #67

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8767fcb
Add a --thinpool argument to lxc-create, to use thin pool backed lvm …
Aug 19, 2013
513f7bc
Document the new --thinpool option
Oct 18, 2013
fa8c1b4
Allocate cmd string with alloca instead of malloc, close popen handle…
Oct 18, 2013
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2 changes: 1 addition & 1 deletion src/lxc/arguments.h
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Expand Up @@ -80,7 +80,7 @@ struct lxc_arguments {
char *bdevtype, *configfile, *template;
char *fstype;
unsigned long fssize;
char *lvname, *vgname;
char *lvname, *vgname, *thinpool;
char *zfsroot, *lowerdir, *dir;

/* remaining arguments */
Expand Down
75 changes: 69 additions & 6 deletions src/lxc/bdev.c
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Expand Up @@ -816,7 +816,7 @@ static int lvm_umount(struct bdev *bdev)
* not yet exist. This function will attempt to create /dev/$vg/$lv of
* size $size.
*/
static int do_lvm_create(const char *path, unsigned long size)
static int do_lvm_create(const char *path, unsigned long size, const char *thinpool)
{
int ret, pid;
char sz[24], *pathdup, *vg, *lv;
Expand Down Expand Up @@ -848,11 +848,61 @@ static int do_lvm_create(const char *path, unsigned long size)
if (!vg)
exit(1);
vg++;
execlp("lvcreate", "lvcreate", "-L", sz, vg, "-n", lv, (char *)NULL);
if (!thinpool) {
execlp("lvcreate", "lvcreate", "-L", sz, vg, "-n", lv, (char *)NULL);
} else {
execlp("lvcreate", "lvcreate", "--thinpool", thinpool, "-V", sz, vg, "-n", lv, (char *)NULL);
}
free(pathdup);
exit(1);
}

static int lvm_is_thin_volume(const char *path)
{
FILE *f;
int ret, len, start=0;
char *cmd, output[12];
const char *lvscmd = "lvs --unbuffered --noheadings -o lv_attr %s 2>/dev/null";

len = strlen(lvscmd) + strlen(path) - 1;
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Why -1 here? The strlen() returns length not including final \0. So I think you actually want a +1 for a final \0. Am I thinking wrong?

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'%s' is 2 chars long and gets replaced by path, so if I'm doing the math right then -1 is correct.

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Gotcha!

cmd = malloc(len);
if (!cmd)
return -1;

ret = snprintf(cmd, len, lvscmd, path);
if (ret < 0 || ret >= len)
return -1;

process_lock();
f = popen(cmd, "r");
process_unlock();

if (f == NULL) {
SYSERROR("popen failed");
return -1;
}

if (fgets(output, 12, f) == NULL)
return -1;

process_lock();
ret = pclose(f);
process_unlock();

if (!WIFEXITED(ret)) {
SYSERROR("error executing lvs");
return -1;
}

len = strlen(output);
while(start < len && output[start] == ' ') start++;

if (start + 6 < len && output[start + 6] == 't')
return 1;

return 0;
}

static int lvm_snapshot(const char *orig, const char *path, unsigned long size)
{
int ret, pid;
Expand Down Expand Up @@ -882,7 +932,18 @@ static int lvm_snapshot(const char *orig, const char *path, unsigned long size)
*lv = '\0';
lv++;

ret = execlp("lvcreate", "lvcreate", "-s", "-L", sz, "-n", lv, orig, (char *)NULL);
// check if the original lv is backed by a thin pool, in which case we
// cannot specify a size that's different from the original size.
ret = lvm_is_thin_volume(orig);
if (ret == -1)
return -1;

if (!ret) {
ret = execlp("lvcreate", "lvcreate", "-s", "-L", sz, "-n", lv, orig, (char *)NULL);
} else {
ret = execlp("lvcreate", "lvcreate", "-s", "-n", lv, orig, (char *)NULL);
}

free(pathdup);
exit(1);
}
Expand Down Expand Up @@ -965,7 +1026,7 @@ static int lvm_clonepaths(struct bdev *orig, struct bdev *new, const char *oldna
return -1;
}
} else {
if (do_lvm_create(new->src, size) < 0) {
if (do_lvm_create(new->src, size, NULL) < 0) {
ERROR("Error creating new lvm blockdev");
return -1;
}
Expand Down Expand Up @@ -998,7 +1059,7 @@ static int lvm_destroy(struct bdev *orig)
static int lvm_create(struct bdev *bdev, const char *dest, const char *n,
struct bdev_specs *specs)
{
const char *vg, *fstype, *lv = n;
const char *vg, *thinpool, *fstype, *lv = n;
unsigned long sz;
int ret, len;

Expand All @@ -1009,6 +1070,8 @@ static int lvm_create(struct bdev *bdev, const char *dest, const char *n,
if (!vg)
vg = default_lvm_vg();

thinpool = specs->u.lvm.thinpool;

/* /dev/$vg/$lv */
if (specs->u.lvm.lv)
lv = specs->u.lvm.lv;
Expand All @@ -1027,7 +1090,7 @@ static int lvm_create(struct bdev *bdev, const char *dest, const char *n,
sz = DEFAULT_FS_SIZE;

INFO("Error creating new lvm blockdev %s size %lu", bdev->src, sz);
if (do_lvm_create(bdev->src, sz) < 0) {
if (do_lvm_create(bdev->src, sz, thinpool) < 0) {
ERROR("Error creating new lvm blockdev %s size %lu", bdev->src, sz);
return -1;
}
Expand Down
1 change: 1 addition & 0 deletions src/lxc/bdev.h
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Expand Up @@ -46,6 +46,7 @@ struct bdev_specs {
char *lv;
char *fstype;
unsigned long fssize; // fs size in bytes
char *thinpool; // lvm thin pool to use, if any
} lvm;
struct {
char *fstype;
Expand Down
1 change: 1 addition & 0 deletions src/lxc/lxc_config.c
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Expand Up @@ -31,6 +31,7 @@ struct lxc_config_items items[] =
{
{ .name = "lxcpath", .fn = &lxc_get_default_config_path, },
{ .name = "lvm_vg", .fn = &lxc_get_default_lvm_vg, },
{ .name = "lvm_thin_pool", .fn = &lxc_get_default_lvm_thin_pool, },
{ .name = "zfsroot", .fn = &lxc_get_default_zfs_root, },
{ .name = NULL, },
};
Expand Down
26 changes: 16 additions & 10 deletions src/lxc/lxc_create.c
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Expand Up @@ -64,10 +64,11 @@ static int my_parser(struct lxc_arguments* args, int c, char* arg)
case 't': args->template = arg; break;
case '0': args->lvname = arg; break;
case '1': args->vgname = arg; break;
case '2': args->fstype = arg; break;
case '3': args->fssize = get_fssize(arg); break;
case '4': args->zfsroot = arg; break;
case '5': args->dir = arg; break;
case '2': args->thinpool = arg; break;
case '3': args->fstype = arg; break;
case '4': args->fssize = get_fssize(arg); break;
case '5': args->zfsroot = arg; break;
case '6': args->dir = arg; break;
}
return 0;
}
Expand All @@ -78,10 +79,11 @@ static const struct option my_longopts[] = {
{"template", required_argument, 0, 't'},
{"lvname", required_argument, 0, '0'},
{"vgname", required_argument, 0, '1'},
{"fstype", required_argument, 0, '2'},
{"fssize", required_argument, 0, '3'},
{"zfsroot", required_argument, 0, '4'},
{"dir", required_argument, 0, '5'},
{"thinpool", required_argument, 0, '2'},
{"fstype", required_argument, 0, '3'},
{"fssize", required_argument, 0, '4'},
{"zfsroot", required_argument, 0, '5'},
{"dir", required_argument, 0, '6'},
LXC_COMMON_OPTIONS
};

Expand Down Expand Up @@ -129,6 +131,8 @@ Options :\n\
(Default: container name)\n\
--vgname=VG Use LVM vg called VG\n\
(Default: lxc))\n\
--thinpool=TP Use LVM thin pool called TP\n\
(Default: none))\n\
--fstype=TYPE Create fstype TYPE\n\
(Default: ext3))\n\
--fssize=SIZE Create filesystem of size SIZE\n\
Expand All @@ -151,8 +155,8 @@ bool validate_bdev_args(struct lxc_arguments *a)
}
}
if (strcmp(a->bdevtype, "lvm") != 0) {
if (a->lvname || a->vgname) {
fprintf(stderr, "--lvname and --vgname are only valid with -B lvm\n");
if (a->lvname || a->vgname || a->thinpool) {
fprintf(stderr, "--lvname, --vgname and --thinpool are only valid with -B lvm\n");
return false;
}
}
Expand Down Expand Up @@ -221,6 +225,8 @@ int main(int argc, char *argv[])
spec.u.lvm.lv = my_args.lvname;
if (my_args.vgname)
spec.u.lvm.vg = my_args.vgname;
if (my_args.thinpool)
spec.u.lvm.thinpool = my_args.thinpool;
if (my_args.fstype)
spec.u.lvm.fstype = my_args.fstype;
if (my_args.fssize)
Expand Down
5 changes: 5 additions & 0 deletions src/lxc/lxccontainer.c
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Expand Up @@ -1807,6 +1807,11 @@ const char *lxc_get_default_lvm_vg(void)
return default_lvm_vg();
}

const char *lxc_get_default_lvm_thin_pool(void)
{
return default_lvm_thin_pool();
}

const char *lxc_get_default_zfs_root(void)
{
return default_zfs_root();
Expand Down
1 change: 1 addition & 0 deletions src/lxc/lxccontainer.h
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Expand Up @@ -245,6 +245,7 @@ int lxc_container_put(struct lxc_container *c);
int lxc_get_wait_states(const char **states);
const char *lxc_get_default_config_path(void);
const char *lxc_get_default_lvm_vg(void);
const char *lxc_get_default_lvm_thin_pool(void);
const char *lxc_get_default_zfs_root(void);
const char *lxc_get_version(void);

Expand Down
6 changes: 6 additions & 0 deletions src/lxc/utils.c
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Expand Up @@ -243,6 +243,7 @@ const char *lxc_global_config_value(const char *option_name)
{
static const char *options[][2] = {
{ "lvm_vg", DEFAULT_VG },
{ "lvm_thin_pool", NULL },
{ "zfsroot", DEFAULT_ZFSROOT },
{ "lxcpath", LXCPATH },
{ "cgroup.pattern", DEFAULT_CGROUP_PATTERN },
Expand Down Expand Up @@ -326,6 +327,11 @@ const char *default_lvm_vg(void)
return lxc_global_config_value("lvm_vg");
}

const char *default_lvm_thin_pool(void)
{
return lxc_global_config_value("lvm_thin_pool");
}

const char *default_zfs_root(void)
{
return lxc_global_config_value("zfsroot");
Expand Down
1 change: 1 addition & 0 deletions src/lxc/utils.h
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Expand Up @@ -48,6 +48,7 @@ extern const char *lxc_global_config_value(const char *option_name);
extern const char *default_lxc_path(void);
extern const char *default_zfs_root(void);
extern const char *default_lvm_vg(void);
extern const char *default_lvm_thin_pool(void);

/* Define getline() if missing from the C library */
#ifndef HAVE_GETLINE
Expand Down