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overlay and aufs clone_paths: be more robust

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Currently when we clone a container, bdev_copy passes NULL as dst argument
of bdev_init, then sees bdev->dest (as a result) is NULL, and sets
bdev->dest to $lxcpath/$name/rootfs.  so $ops->clone_paths() can
assume that "/rootfs" is at the end of the path.  The overlayfs and
aufs clonepaths do assume that and index to endofstring-6 and append
delta0.  Let's be more robust by actually finding the last / in
the path.

Then, instead of always setting oldbdev->dest to $lxcpath/$name/rootfs,
set it to oldbdev->src.  Else dir_clonepaths fails when mounting src
onto dest bc dest does not exist.  We could also fix that by creating
bdev->dest if needed, but that addes an empty directory to the old
container.

This fixes 'lxc-clone -o x1 -n x2' if x1 has lxc.rootfs = /var/lib/lxc/x1/x
and makes the overlayfs and aufs paths less fragile should something else
change.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>
This commit is contained in:
Serge Hallyn 2014-10-16 15:10:21 +00:00 committed by Stéphane Graber
parent cfa70b8824
commit edf77341a5
1 changed files with 30 additions and 38 deletions
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68
src/lxc/bdev.c
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@ -2265,20 +2265,24 @@ 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;
int ret, len;
char *delta, *lastslash;
int ret, len, lastslashidx;
// if we have /var/lib/lxc/c2/rootfs, then delta will be
// /var/lib/lxc/c2/delta0
delta = strdup(new->dest);
if (!delta) {
return -1;
}
if (strlen(delta) < 6) {
free(delta);
lastslash = strrchr(new->dest, '/');
if (!lastslash)
return -22;
}
strcpy(&delta[strlen(delta)-6], "delta0");
if (strlen(lastslash) < 7)
return -22;
lastslash++;
lastslashidx = lastslash - new->dest;
delta = malloc(lastslashidx + 7);
if (!delta)
return -1;
strncpy(delta, new->dest, lastslashidx+1);
strcpy(delta+lastslashidx, "delta0");
if ((ret = mkdir(delta, 0755)) < 0) {
SYSERROR("error: mkdir %s", delta);
free(delta);
@ -2319,7 +2323,7 @@ static int overlayfs_clonepaths(struct bdev *orig, struct bdev *new, const char
free(osrc);
return -ENOMEM;
}
if ((ret = mkdir(ndelta, 0755)) < 0) {
if ((ret = mkdir(ndelta, 0755)) < 0 && errno != EEXIST) {
SYSERROR("error: mkdir %s", ndelta);
free(osrc);
free(ndelta);
@ -2560,20 +2564,24 @@ static int aufs_clonepaths(struct bdev *orig, struct bdev *new, const char *oldn
return -1;
if (strcmp(orig->type, "dir") == 0) {
char *delta;
int ret, len;
char *delta, *lastslash;
int ret, len, lastslashidx;
// if we have /var/lib/lxc/c2/rootfs, then delta will be
// /var/lib/lxc/c2/delta0
delta = strdup(new->dest);
if (!delta) {
return -1;
}
if (strlen(delta) < 6) {
free(delta);
lastslash = strrchr(new->dest, '/');
if (!lastslash)
return -22;
}
strcpy(&delta[strlen(delta)-6], "delta0");
if (strlen(lastslash) < 7)
return -22;
lastslash++;
lastslashidx = lastslash - new->dest;
delta = malloc(lastslashidx + 7);
if (!delta)
return -1;
strncpy(delta, new->dest, lastslashidx+1);
strcpy(delta+lastslashidx, "delta0");
if ((ret = mkdir(delta, 0755)) < 0) {
SYSERROR("error: mkdir %s", delta);
free(delta);
@ -3248,28 +3256,12 @@ struct bdev *bdev_copy(struct lxc_container *c0, const char *cname,
return NULL;
}
orig = bdev_init(c0->lxc_conf, src, NULL, NULL);
orig = bdev_init(c0->lxc_conf, src, src, NULL);
if (!orig) {
ERROR("failed to detect blockdev type for %s", src);
return NULL;
}
if (!orig->dest) {
int ret;
orig->dest = malloc(MAXPATHLEN);
if (!orig->dest) {
ERROR("out of memory");
bdev_put(orig);
return NULL;
}
ret = snprintf(orig->dest, MAXPATHLEN, "%s/%s/rootfs", oldpath, oldname);
if (ret < 0 || ret >= MAXPATHLEN) {
ERROR("rootfs path too long");
bdev_put(orig);
return NULL;
}
}
/*
* special case for snapshot - if caller requested maybe_snapshot and
* keepbdevtype and backing store is directory, then proceed with a copy