[lxc-devel] [PATCH] snapshot: fix overlayfs restore

Stéphane Graber stgraber at ubuntu.com
Tue Mar 4 22:40:01 UTC 2014


On Tue, Mar 04, 2014 at 02:54:04PM -0600, Serge Hallyn wrote:
> And add a testcase to catch regressions.
> 
> Without this patch, restoring a snapshot of an overlayfs based
> container fails, because we do not pass in LXC_CLONE_SNAPSHOT,
> and overlayfs does not support clone without snapshot.
> 

Acked-by: Stéphane Graber <stgraber at ubuntu.com>

> Signed-off-by: Serge Hallyn <serge.hallyn at ubuntu.com>
> ---
>  src/lxc/lxccontainer.c |  7 +++++--
>  src/tests/snapshot.c   | 53 ++++++++++++++++++++++++++++++++++++++++++++++++--
>  2 files changed, 56 insertions(+), 4 deletions(-)
> 
> diff --git a/src/lxc/lxccontainer.c b/src/lxc/lxccontainer.c
> index b0ae44b..877e491 100644
> --- a/src/lxc/lxccontainer.c
> +++ b/src/lxc/lxccontainer.c
> @@ -3045,7 +3045,7 @@ out_free:
>  static bool lxcapi_snapshot_restore(struct lxc_container *c, const char *snapname, const char *newname)
>  {
>  	char clonelxcpath[MAXPATHLEN];
> -	int ret;
> +	int flags = 0,ret;
>  	struct lxc_container *snap, *rest;
>  	struct bdev *bdev;
>  	bool b = false;
> @@ -3083,7 +3083,10 @@ static bool lxcapi_snapshot_restore(struct lxc_container *c, const char *snapnam
>  		return false;
>  	}
>  
> -	rest = lxcapi_clone(snap, newname, c->config_path, 0, bdev->type, NULL, 0, NULL);
> +	if (strcmp(bdev->type, "dir") != 0 && strcmp(bdev->type, "loop") != 0)
> +		flags = LXC_CLONE_SNAPSHOT | LXC_CLONE_MAYBE_SNAPSHOT;
> +	rest = lxcapi_clone(snap, newname, c->config_path, flags,
> +			bdev->type, NULL, 0, NULL);
>  	bdev_put(bdev);
>  	if (rest && lxcapi_is_defined(rest))
>  		b = true;
> diff --git a/src/tests/snapshot.c b/src/tests/snapshot.c
> index fe06077..09cee1a 100644
> --- a/src/tests/snapshot.c
> +++ b/src/tests/snapshot.c
> @@ -26,6 +26,7 @@
>  #include "lxc/lxc.h"
>  
>  #define MYNAME "snapxxx1"
> +#define MYNAME2 "snapxxx3"
>  #define RESTNAME "snapxxx2"
>  
>  static void try_to_remove(void)
> @@ -45,6 +46,12 @@ static void try_to_remove(void)
>  			c->destroy(c);
>  		lxc_container_put(c);
>  	}
> +	c = lxc_container_new(MYNAME2, NULL);
> +	if (c) {
> +		if (c->is_defined(c))
> +			c->destroy(c);
> +		lxc_container_put(c);
> +	}
>  	c = lxc_container_new(MYNAME, NULL);
>  	if (c) {
>  		if (c->is_defined(c))
> @@ -55,7 +62,7 @@ static void try_to_remove(void)
>  
>  int main(int argc, char *argv[])
>  {
> -	struct lxc_container *c;
> +	struct lxc_container *c, *c2 = NULL;
>  	char *template = "busybox";
>  
>  	if (argc > 1)
> @@ -84,7 +91,7 @@ int main(int argc, char *argv[])
>  	c->load_config(c, NULL);
>  
>  	if (c->snapshot(c, NULL) != 0) {
> -		fprintf(stderr, "%s: %d: failed to create snapsot\n", __FILE__, __LINE__);
> +		fprintf(stderr, "%s: %d: failed to create snapshot\n", __FILE__, __LINE__);
>  		goto err;
>  	}
>  
> @@ -126,6 +133,48 @@ int main(int argc, char *argv[])
>  		goto err;
>  	}
>  
> +
> +	c2 = c->clone(c, MYNAME2, NULL, LXC_CLONE_SNAPSHOT, "overlayfs", NULL, 0, NULL);
> +	if (!c2) {
> +		fprintf(stderr, "%d: %s overlayfs clone failed\n", __LINE__, MYNAME2);
> +		goto good;
> +	}
> +
> +	if (c2->snapshot(c2, NULL) != 0) {
> +		fprintf(stderr, "%s: %d: failed to create snapshot\n", __FILE__, __LINE__);
> +		goto err;
> +	}
> +
> +	n = c2->snapshot_list(c2, &s);
> +	if (n < 1) {
> +		fprintf(stderr, "%s: %d: failed listing containers\n", __FILE__, __LINE__);
> +		goto err;
> +	}
> +	if (strcmp(s->name, "snap0") != 0) {
> +		fprintf(stderr, "%s: %d: snapshot had bad name\n", __FILE__, __LINE__);
> +		goto err;
> +	}
> +	for (i=0; i<n; i++) {
> +		s[i].free(&s[i]);
> +	}
> +	free(s);
> +
> +	if (!c2->snapshot_restore(c2, "snap0", NULL)) {
> +		fprintf(stderr, "%s: %d: failed to restore overlayfs snapshot\n", __FILE__, __LINE__);
> +		goto err;
> +	}
> +
> +	if (!c2->snapshot_destroy(c2, "snap0")) {
> +		fprintf(stderr, "%s: %d: failed to destroy overlayfs snapshot\n", __FILE__, __LINE__);
> +		goto err;
> +	}
> +
> +	if (!c2->destroy(c2)) {
> +		fprintf(stderr, "%s: %d: failed to destroy container\n", __FILE__, __LINE__);
> +		goto err;
> +	}
> +
> +good:
>  	if (!c->destroy(c)) {
>  		fprintf(stderr, "%s: %d: failed to destroy container\n", __FILE__, __LINE__);
>  		goto err;
> -- 
> 1.9.0
> 
> _______________________________________________
> lxc-devel mailing list
> lxc-devel at lists.linuxcontainers.org
> http://lists.linuxcontainers.org/listinfo/lxc-devel

-- 
Stéphane Graber
Ubuntu developer
http://www.ubuntu.com
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