Hi, Sorry for my slow response.
>>> On Wed, 8 Oct 2014 18:21:19 +0000
in message "Re: [lxc-devel] lxc-clone do not work when overlayfs.v22 or
higher is used"
Serge Hallyn-san wrote:
> Quoting KATOH Yasufumi (ka...@jazz.email.ne.jp):
> > Hi,
> >
> > Now, lxc-clone with overlayfs (lxc-clone -s -B overlayfs) runs internally:
> > mount -t overlayfs -oupperdir=${upper},lowerdir=${lower} lower dest
> >
> > But, overlayfs.v22(kernel 3.15) or higher need the option "workdir=",
> > so lxc-clone do not work.
> >
> > On 3.17 with overlayfs.v24, without workdir option:
> > # mount -n -t overlayfs -o lowerdir=1,upperdir=2 overlayfs 3
> > mount: wrong fs type, bad option, bad superblock on overlayfs,
> > missing codepage or helper program, or other error
> >
> > In some cases useful info is found in syslog - try
> > dmesg | tail or so.
> > # dmesg | tail
> > [ 683.456473] overlayfs: missing upperdir or lowerdir or workdir
> >
> > On 3.17 with overlayfs.v24, with workdir option:
> > # mount -n -t overlayfs -o lowerdir=1,upperdir=2,workdir=3 overlayfs 4
> > # cat /proc/mounts | grep overlayfs
> > overlayfs /root/overlayfs/4 overlayfs
> > rw,relatime,lowerdir=1,upperdir=2,workdir=3 0 0
> >
> > See
> >
> > https://git.kernel.org/cgit/linux/kernel/git/mszeredi/vfs.git/tree/Documentation/filesystems/overlayfs.txt?h=overlayfs.v24
> The older version (which is still in use in the 3.16 kernel in Ubuntu 14.10)
> fails with that option, so it looks like there's not much to do but try
> the workdir=, then if that fails try without workdir=.
> Can you send a patch to do that?
I try it. But I don't know well the details of the clone process, I
don't know whether this is right.
This patch is
* the workdir is LXCPATH/ct/olwork.
* mkdir workdir when clone
* mount without workdir is failed, then retry mount with workdir
I've tested on:
* 3.14.4 with overlayfs.v21 (not need workdir=) (priv and unpriv)
* 3.17.0 with overlayfs.v24 (need workdir=) (priv and unpriv)
Signed-off-by: KATOH Yasufumi <ka...@jazz.email.ne.jp>
---
src/lxc/bdev.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++++++++------
1 file changed, 70 insertions(+), 7 deletions(-)
diff --git a/src/lxc/bdev.c b/src/lxc/bdev.c
index 4fc10f2..69c2e7f 100644
--- a/src/lxc/bdev.c
+++ b/src/lxc/bdev.c
@@ -2154,10 +2154,11 @@ static int overlayfs_detect(const char *path)
static int overlayfs_mount(struct bdev *bdev)
{
char *options, *dup, *lower, *upper;
- int len;
+ char *options_work, *work, *worktmp;
+ int len, len2;
unsigned long mntflags;
char *mntdata;
- int ret;
+ int ret, ret2;
if (strcmp(bdev->type, "overlayfs"))
return -22;
@@ -2175,6 +2176,14 @@ static int overlayfs_mount(struct bdev *bdev)
*upper = '\0';
upper++;
+ // workdir option that is needed overlayfs.v22 or higher
+ // workdir=$LXCDIR/ct/olwork
+ work = alloca(strlen(upper)+1);
+ strcpy(work, upper);
+ if (!(worktmp = rindex(work, '/')))
+ return -22;
+ strncpy(worktmp+1, "olwork", 6);
+
if (parse_mntopts(bdev->mntopts, &mntflags, &mntdata) < 0) {
free(mntdata);
return -22;
@@ -2187,21 +2196,42 @@ static int overlayfs_mount(struct bdev *bdev)
len = strlen(lower) + strlen(upper) +
strlen("upperdir=,lowerdir=,") + strlen(mntdata) + 1;
options = alloca(len);
ret = snprintf(options, len, "upperdir=%s,lowerdir=%s,%s",
upper, lower, mntdata);
+
+ len2 = strlen(lower) + strlen(upper) + strlen(work)
+ + strlen("upperdir=,lowerdir=,workdir=") +
strlen(mntdata) + 1;
+ options_work = alloca(len2);
+ ret2 = snprintf(options, len2,
"upperdir=%s,lowerdir=%s,workdir=%s,%s",
+ upper, lower, work, mntdata);
}
else {
len = strlen(lower) + strlen(upper) +
strlen("upperdir=,lowerdir=") + 1;
options = alloca(len);
ret = snprintf(options, len, "upperdir=%s,lowerdir=%s", upper,
lower);
+
+ len2 = strlen(lower) + strlen(upper) + strlen(work)
+ + strlen("upperdir=,lowerdir=,workdir=") + 1;
+ options_work = alloca(len2);
+ ret2 = snprintf(options_work, len2,
"upperdir=%s,lowerdir=%s,workdir=%s",
+ upper, lower, work);
}
- if (ret < 0 || ret >= len) {
+ if (ret < 0 || ret >= len || ret2 < 0 || ret2 >= len2) {
free(mntdata);
return -1;
}
ret = mount(lower, bdev->dest, "overlayfs", MS_MGC_VAL | mntflags,
options);
- if (ret < 0)
- SYSERROR("overlayfs: error mounting %s onto %s options %s",
+ if (ret < 0) {
+ WARN("overlayfs: error mounting %s onto %s options %s",
lower, bdev->dest, options);
+ // retry with workdir option
+ ret = mount(lower, bdev->dest, "overlayfs", MS_MGC_VAL |
mntflags, options_work);
+ if (ret < 0)
+ SYSERROR("overlayfs: error mounting %s onto %s options
%s",
+ lower, bdev->dest, options_work);
+ else
+ INFO("overlayfs: mounted %s onto %s options %s",
+ lower, bdev->dest, options_work);
+ }
else
INFO("overlayfs: mounted %s onto %s options %s",
lower, bdev->dest, options);
@@ -2265,7 +2295,7 @@ static int overlayfs_clonepaths(struct bdev *orig, struct
bdev *new, const char
WARN("Failed to update ownership of %s", new->dest);
if (strcmp(orig->type, "dir") == 0) {
- char *delta;
+ char *delta, *work;
int ret, len;
// if we have /var/lib/lxc/c2/rootfs, then delta will be
@@ -2287,6 +2317,23 @@ static int overlayfs_clonepaths(struct bdev *orig,
struct bdev *new, const char
if (am_unpriv() && chown_mapped_root(delta, conf) < 0)
WARN("Failed to update ownership of %s", delta);
+ // mkdir workdir that is needed on overlayfs.v22 or higher
+ // if we have /var/lib/lxc/c2/rootfs, then workdir will be
+ // /var/lib/lxc/c2/olwork
+ work = strdup(new->dest);
+ if (!work)
+ return -1;
+
+ strcpy(&work[strlen(work)-6], "olwork");
+ if (mkdir(work, 0755) < 0) {
+ SYSERROR("error: mkdir %s", work);
+ free(work);
+ return -1;
+ }
+ if (am_unpriv() && chown_mapped_root(work, conf) < 0)
+ WARN("Failed to update ownership of %s", work);
+ free(work);
+
// the src will be 'overlayfs:lowerdir:upperdir'
len = strlen(delta) + strlen(orig->src) + 12;
new->src = malloc(len);
@@ -2303,7 +2350,7 @@ static int overlayfs_clonepaths(struct bdev *orig, struct
bdev *new, const char
// I think we want to use the original lowerdir, with a
// private delta which is originally rsynced from the
// original delta
- char *osrc, *odelta, *nsrc, *ndelta;
+ char *osrc, *odelta, *nsrc, *ndelta, *work;
int len, ret;
if (!(osrc = strdup(orig->src)))
return -22;
@@ -2327,6 +2374,22 @@ static int overlayfs_clonepaths(struct bdev *orig,
struct bdev *new, const char
}
if (am_unpriv() && chown_mapped_root(ndelta, conf) < 0)
WARN("Failed to update ownership of %s", ndelta);
+
+ // mkdir workdir for overlayfs.v22 or later
+ work = strdup(ndelta);
+ if (!work)
+ return -1;
+
+ strcpy(&work[strlen(work)-6], "olwork");
+ if (mkdir(work, 0755) < 0) {
+ SYSERROR("error: mkdir %s", work);
+ free(work);
+ return -1;
+ }
+ if (am_unpriv() && chown_mapped_root(work, conf) < 0)
+ WARN("Failed to update ownership of %s", work);
+ free(work);
+
struct rsync_data_char rdata;
rdata.src = odelta;
rdata.dest = ndelta;
--
2.1.1
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