Merge pull request #724 from brauner/2015-12-12/split_bdev_into_modules

src/lxc/Makefile.am

@@ -6,7 +6,9 @@ pkginclude_HEADERS = \
 noinst_HEADERS = \
 	arguments.h \
 	attach.h \
-	bdev.h \
+	bdev/bdev.h \
+	bdev/lxc-btrfs.h \
+	bdev/overlay.h \
 	caps.h \
 	cgroup.h \
 	conf.h \
@@ -16,7 +18,6 @@ noinst_HEADERS = \
 	list.h \
 	log.h \
 	lxc.h \
-	lxc-btrfs.h \
 	lxclock.h \
 	monitor.h \
 	namespace.h \
@@ -60,7 +61,7 @@ endif
 
 liblxc_so_SOURCES = \
 	arguments.c arguments.h \
-	bdev.c bdev.h lxc-btrfs.h \
+	bdev/bdev.c bdev/bdev.h bdev/overlay.c bdev/overlay.h bdev/lxc-btrfs.h \
 	commands.c commands.h \
 	start.c start.h \
 	execute.c \

src/lxc/bdev.c → src/lxc/bdev/bdev.c

@@ -27,33 +27,38 @@
  * I'm doing by calling out to userspace should sometimes be done through
  * libraries like liblvm2
  */
+
 #define _GNU_SOURCE
-#include <stdio.h>
-#include <stdint.h>
-#include <inttypes.h>
-#include <sys/types.h>
-#include <grp.h>
-#include <unistd.h>
+#include <dirent.h>
 #include <errno.h>
-#include <sched.h>
-#include <sys/mount.h>
-#include <sys/wait.h>
+#include <fcntl.h>
+#include <grp.h>
+#include <inttypes.h>
 #include <libgen.h>
+#include <sched.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
 #include <linux/loop.h>
-#include <dirent.h>
+#include <sys/mount.h>
 #include <sys/prctl.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/wait.h>
 
-#include "lxc.h"
+#include "bdev.h"
 #include "config.h"
 #include "conf.h"
-#include "bdev.h"
-#include "log.h"
 #include "error.h"
-#include "utils.h"
-#include "namespace.h"
-#include "parse.h"
+#include "log.h"
+#include "lxc.h"
 #include "lxclock.h"
 #include "lxc-btrfs.h"
+#include "namespace.h"
+#include "overlay.h" /* overlay */
+#include "parse.h"
+#include "utils.h"
 
 #ifndef BLKGETSIZE64
 #define BLKGETSIZE64 _IOR(0x12,114,size_t)
@@ -72,17 +77,13 @@
 
 lxc_log_define(bdev, lxc);
 
-struct ovl_rsync_data {
-	struct bdev *orig;
-	struct bdev *new;
-};
-
 struct rsync_data_char {
 	char *src;
 	char *dest;
 };
 
-static int do_rsync(const char *src, const char *dest)
+/* the bulk of this needs to become a common helper */
+int do_rsync(const char *src, const char *dest)
 {
 	// call out to rsync
 	pid_t pid;
@@ -107,6 +108,48 @@ static int do_rsync(const char *src, const char *dest)
 	exit(1);
 }
 
+/* the bulk of this needs to become a common helper */
+char *dir_new_path(char *src, const char *oldname, const char *name,
+			const char *oldpath, const char *lxcpath)
+{
+	char *ret, *p, *p2;
+	int l1, l2, nlen;
+
+	nlen = strlen(src) + 1;
+	l1 = strlen(oldpath);
+	p = src;
+	/* if src starts with oldpath, look for oldname only after
+	 * that path */
+	if (strncmp(src, oldpath, l1) == 0) {
+		p += l1;
+		nlen += (strlen(lxcpath) - l1);
+	}
+	l2 = strlen(oldname);
+	while ((p = strstr(p, oldname)) != NULL) {
+		p += l2;
+		nlen += strlen(name) - l2;
+	}
+
+	ret = malloc(nlen);
+	if (!ret)
+		return NULL;
+
+	p = ret;
+	if (strncmp(src, oldpath, l1) == 0) {
+		p += sprintf(p, "%s", lxcpath);
+		src += l1;
+	}
+
+	while ((p2 = strstr(src, oldname)) != NULL) {
+		strncpy(p, src, p2-src); // copy text up to oldname
+		p += p2-src; // move target pointer (p)
+		p += sprintf(p, "%s", name); // print new name in place of oldname
+		src = p2 + l2;  // move src to end of oldname
+	}
+	sprintf(p, "%s", src);  // copy the rest of src
+	return ret;
+}
+
 /*
  * return block size of dev->src in units of bytes
  */
@@ -404,48 +447,6 @@ static int dir_umount(struct bdev *bdev)
 	return umount(bdev->dest);
 }
 
-/* the bulk of this needs to become a common helper */
-static char *dir_new_path(char *src, const char *oldname, const char *name,
-			const char *oldpath, const char *lxcpath)
-{
-	char *ret, *p, *p2;
-	int l1, l2, nlen;
-
-	nlen = strlen(src) + 1;
-	l1 = strlen(oldpath);
-	p = src;
-	/* if src starts with oldpath, look for oldname only after
-	 * that path */
-	if (strncmp(src, oldpath, l1) == 0) {
-		p += l1;
-		nlen += (strlen(lxcpath) - l1);
-	}
-	l2 = strlen(oldname);
-	while ((p = strstr(p, oldname)) != NULL) {
-		p += l2;
-		nlen += strlen(name) - l2;
-	}
-
-	ret = malloc(nlen);
-	if (!ret)
-		return NULL;
-
-	p = ret;
-	if (strncmp(src, oldpath, l1) == 0) {
-		p += sprintf(p, "%s", lxcpath);
-		src += l1;
-	}
-
-	while ((p2 = strstr(src, oldname)) != NULL) {
-		strncpy(p, src, p2-src); // copy text up to oldname
-		p += p2-src; // move target pointer (p)
-		p += sprintf(p, "%s", name); // print new name in place of oldname
-		src = p2 + l2;  // move src to end of oldname
-	}
-	sprintf(p, "%s", src);  // copy the rest of src
-	return ret;
-}
-
 /*
  * for a simple directory bind mount, we substitute the old container
  * name and paths for the new
@@ -2321,158 +2322,6 @@ static const struct bdev_ops loop_ops = {
 	.can_backup = true,
 };
 
-//
-// overlayfs ops
-//
-
-static int overlayfs_detect(const char *path)
-{
-	if (strncmp(path, "overlayfs:", 10) == 0)
-		return 1; // take their word for it
-	return 0;
-}
-
-static char *overlayfs_name;
-static char *detect_overlayfs_name(void)
-{
-	char *v = "overlayfs";
-	char *line = NULL;
-	size_t len = 0;
-	FILE *f = fopen("/proc/filesystems", "r");
-	if (!f)
-		return v;
-
-	while (getline(&line, &len, f) != -1) {
-		if (strcmp(line, "nodev\toverlay\n") == 0) {
-			v = "overlay";
-			break;
-		}
-	}
-
-	fclose(f);
-	free(line);
-	return v;
-}
-
-//
-// XXXXXXX plain directory bind mount ops
-//
-static int overlayfs_mount(struct bdev *bdev)
-{
-	char *options, *dup, *lower, *upper;
-	char *options_work, *work, *lastslash;
-	int lastslashidx;
-	int len, len2;
-	unsigned long mntflags;
-	char *mntdata;
-	int ret, ret2;
-
-	if (strcmp(bdev->type, "overlayfs"))
-		return -22;
-	if (!bdev->src || !bdev->dest)
-		return -22;
-
-	if (!overlayfs_name)
-		overlayfs_name = detect_overlayfs_name();
-
-	//  separately mount it first
-	//  mount -t overlayfs -oupperdir=${upper},lowerdir=${lower} lower dest
-	dup = alloca(strlen(bdev->src)+1);
-	strcpy(dup, bdev->src);
-	if (!(lower = strchr(dup, ':')))
-		return -22;
-	if (!(upper = strchr(++lower, ':')))
-		return -22;
-	*upper = '\0';
-	upper++;
-
-	// if delta doesn't yet exist, create it
-	if (mkdir_p(upper, 0755) < 0 && errno != EEXIST)
-		return -22;
-
-	// overlayfs.v22 or higher needs workdir option
-	// if upper is /var/lib/lxc/c2/delta0,
-	// then workdir is /var/lib/lxc/c2/olwork
-	lastslash = strrchr(upper, '/');
-	if (!lastslash)
-		return -22;
-	lastslash++;
-	lastslashidx = lastslash - upper;
-
-	work = alloca(lastslashidx + 7);
-	strncpy(work, upper, lastslashidx+7);
-	strcpy(work+lastslashidx, "olwork");
-
-	if (parse_mntopts(bdev->mntopts, &mntflags, &mntdata) < 0) {
-		free(mntdata);
-		return -22;
-	}
-
-	if (mkdir_p(work, 0755) < 0 && errno != EEXIST) {
-		free(mntdata);
-		return -22;
-	}
-
-	// TODO We should check whether bdev->src is a blockdev, and if so
-	// but for now, only support overlays of a basic directory
-
-	if (mntdata) {
-		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 || ret2 < 0 || ret2 >= len2) {
-		free(mntdata);
-		return -1;
-	}
-
-	// mount without workdir option for overlayfs before v21
-	ret = mount(lower, bdev->dest, overlayfs_name, MS_MGC_VAL | mntflags, options);
-	if (ret < 0) {
-		INFO("overlayfs: error mounting %s onto %s options %s. retry with workdir",
-			lower, bdev->dest, options);
-
-		// retry with workdir option for overlayfs v22 and higher
-		ret = mount(lower, bdev->dest, overlayfs_name, 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);
-	return ret;
-}
-
-static int overlayfs_umount(struct bdev *bdev)
-{
-	if (strcmp(bdev->type, "overlayfs"))
-		return -22;
-	if (!bdev->src || !bdev->dest)
-		return -22;
-	return umount(bdev->dest);
-}
-
 static int rsync_delta(struct rsync_data_char *data)
 {
 	if (setgid(0) < 0) {
@@ -2499,303 +2348,14 @@ static int rsync_delta_wrapper(void *data)
 	return rsync_delta(arg);
 }
 
-static int ovl_rsync(struct ovl_rsync_data *data)
-{
-	int ret;
-
-	if (setgid(0) < 0) {
-		ERROR("Failed to setgid to 0");
-		return -1;
-	}
-	if (setgroups(0, NULL) < 0)
-		WARN("Failed to clear groups");
-	if (setuid(0) < 0) {
-		ERROR("Failed to setuid to 0");
-		return -1;
-	}
-
-	if (unshare(CLONE_NEWNS) < 0) {
-		SYSERROR("Unable to unshare mounts ns");
-		return -1;
-	}
-	if (detect_shared_rootfs()) {
-		if (mount(NULL, "/", NULL, MS_SLAVE|MS_REC, NULL)) {
-			SYSERROR("Failed to make / rslave");
-			ERROR("Continuing...");
-		}
-	}
-	if (overlayfs_mount(data->orig) < 0) {
-		ERROR("Failed mounting original container fs");
-		return -1;
-	}
-	if (overlayfs_mount(data->new) < 0) {
-		ERROR("Failed mounting new container fs");
-		return -1;
-	}
-	ret = do_rsync(data->orig->dest, data->new->dest);
-
-	overlayfs_umount(data->new);
-	overlayfs_umount(data->orig);
-
-	if (ret < 0) {
-		ERROR("rsyncing %s to %s", data->orig->dest, data->new->dest);
-		return -1;
-	}
-
-	return 0;
-}
-
-static int ovl_rsync_wrapper(void *data)
-{
-	struct ovl_rsync_data *arg = data;
-	return ovl_rsync(arg);
-}
-
-static int ovl_do_rsync(struct bdev *orig, struct bdev *new, struct lxc_conf *conf)
-{
-	int ret = -1;
-	struct ovl_rsync_data rdata;
-
-	rdata.orig = orig;
-	rdata.new = new;
-	if (am_unpriv())
-		ret = userns_exec_1(conf, ovl_rsync_wrapper, &rdata);
-	else
-		ret = ovl_rsync(&rdata);
-	if (ret)
-		ERROR("copying overlayfs delta");
-
-	return ret;
-}
-
-static int overlayfs_clonepaths(struct bdev *orig, struct bdev *new, const char *oldname,
-		const char *cname, const char *oldpath, const char *lxcpath, int snap,
-		uint64_t newsize, struct lxc_conf *conf)
-{
-	if (!snap) {
-		ERROR("overlayfs is only for snapshot clones");
-		return -22;
-	}
-
-	if (!orig->src || !orig->dest)
-		return -1;
-
-	new->dest = dir_new_path(orig->dest, oldname, cname, oldpath, lxcpath);
-	if (!new->dest)
-		return -1;
-	if (mkdir_p(new->dest, 0755) < 0)
-		return -1;
-
-	if (am_unpriv() && chown_mapped_root(new->dest, conf) < 0)
-		WARN("Failed to update ownership of %s", new->dest);
-
-	if (strcmp(orig->type, "dir") == 0) {
-		char *delta, *lastslash;
-		char *work;
-		int ret, len, lastslashidx;
-
-		// if we have /var/lib/lxc/c2/rootfs, then delta will be
-		//            /var/lib/lxc/c2/delta0
-		lastslash = strrchr(new->dest, '/');
-		if (!lastslash)
-			return -22;
-		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);
-			return -1;
-		}
-		if (am_unpriv() && chown_mapped_root(delta, conf) < 0)
-			WARN("Failed to update ownership of %s", delta);
-
-		// make workdir for overlayfs.v22 or higher
-		// workdir is /var/lib/lxc/c2/olwork
-		// it is used to prepare files before atomically swithing with destination,
-		// and needs to be on the same filesystem as upperdir,
-		// so it's OK for it to be empty.
-		work = malloc(lastslashidx + 7);
-		if (!work) {
-			free(delta);
-			return -1;
-		}
-		strncpy(work, new->dest, lastslashidx+1);
-		strcpy(work+lastslashidx, "olwork");
-		if (mkdir(work, 0755) < 0) {
-			SYSERROR("error: mkdir %s", work);
-			free(delta);
-			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);
-		if (!new->src) {
-			free(delta);
-			return -ENOMEM;
-		}
-		ret = snprintf(new->src, len, "overlayfs:%s:%s", orig->src, delta);
-		free(delta);
-		if (ret < 0 || ret >= len)
-			return -ENOMEM;
-	} else if (strcmp(orig->type, "overlayfs") == 0) {
-		// What exactly do we want to do here?
-		// 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, *work;
-		char *lastslash;
-		int len, ret, lastslashidx;
-		if (!(osrc = strdup(orig->src)))
-			return -22;
-		nsrc = strchr(osrc, ':') + 1;
-		if (nsrc != osrc + 10 || (odelta = strchr(nsrc, ':')) == NULL) {
-			free(osrc);
-			return -22;
-		}
-		*odelta = '\0';
-		odelta++;
-		ndelta = dir_new_path(odelta, oldname, cname, oldpath, lxcpath);
-		if (!ndelta) {
-			free(osrc);
-			return -ENOMEM;
-		}
-		if ((ret = mkdir(ndelta, 0755)) < 0 && errno != EEXIST) {
-			SYSERROR("error: mkdir %s", ndelta);
-			free(osrc);
-			free(ndelta);
-			return -1;
-		}
-		if (am_unpriv() && chown_mapped_root(ndelta, conf) < 0)
-			WARN("Failed to update ownership of %s", ndelta);
-
-		// make workdir for overlayfs.v22 or higher
-		// for details, see above.
-		lastslash = strrchr(ndelta, '/');
-		if (!lastslash)
-			return -1;
-		lastslash++;
-		lastslashidx = lastslash - ndelta;
-
-		work = malloc(lastslashidx + 7);
-		if (!work)
-			return -1;
-		strncpy(work, ndelta, lastslashidx+1);
-		strcpy(work+lastslashidx, "olwork");
-		if ((mkdir(work, 0755) < 0) && errno != EEXIST) {
-			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);
-
-		len = strlen(nsrc) + strlen(ndelta) + 12;
-		new->src = malloc(len);
-		if (!new->src) {
-			free(osrc);
-			free(ndelta);
-			return -ENOMEM;
-		}
-		ret = snprintf(new->src, len, "overlayfs:%s:%s", nsrc, ndelta);
-		free(osrc);
-		free(ndelta);
-		if (ret < 0 || ret >= len)
-			return -ENOMEM;
-
-		return ovl_do_rsync(orig, new, conf);
-	} else {
-		ERROR("overlayfs clone of %s container is not yet supported",
-			orig->type);
-		// Note, supporting this will require overlayfs_mount supporting
-		// mounting of the underlay.  No big deal, just needs to be done.
-		return -1;
-	}
-
-	return 0;
-}
-
-static int overlayfs_destroy(struct bdev *orig)
-{
-	char *upper;
-
-	if (strncmp(orig->src, "overlayfs:", 10) != 0)
-		return -22;
-	upper = strchr(orig->src + 10, ':');
-	if (!upper)
-		return -22;
-	upper++;
-	return lxc_rmdir_onedev(upper, NULL);
-}
-
-/*
- * to say 'lxc-create -t ubuntu -n o1 -B overlayfs' means you want
- * $lxcpath/$lxcname/rootfs to have the created container, while all
- * changes after starting the container are written to
- * $lxcpath/$lxcname/delta0
- */
-static int overlayfs_create(struct bdev *bdev, const char *dest, const char *n,
-			struct bdev_specs *specs)
-{
-	char *delta;
-	int ret, len = strlen(dest), newlen;
-
-	if (len < 8 || strcmp(dest+len-7, "/rootfs") != 0)
-		return -1;
-
-	if (!(bdev->dest = strdup(dest))) {
-		ERROR("Out of memory");
-		return -1;
-	}
-
-	delta = alloca(strlen(dest)+1);
-	strcpy(delta, dest);
-	strcpy(delta+len-6, "delta0");
-
-	if (mkdir_p(delta, 0755) < 0) {
-		ERROR("Error creating %s", delta);
-		return -1;
-	}
-
-	/* overlayfs:lower:upper */
-	newlen = (2 * len) + strlen("overlayfs:") + 2;
-	bdev->src = malloc(newlen);
-	if (!bdev->src) {
-		ERROR("Out of memory");
-		return -1;
-	}
-	ret = snprintf(bdev->src, newlen, "overlayfs:%s:%s", dest, delta);
-	if (ret < 0 || ret >= newlen)
-		return -1;
-
-	if (mkdir_p(bdev->dest, 0755) < 0) {
-		ERROR("Error creating %s", bdev->dest);
-		return -1;
-	}
-
-	return 0;
-}
-
-static const struct bdev_ops overlayfs_ops = {
-	.detect = &overlayfs_detect,
-	.mount = &overlayfs_mount,
-	.umount = &overlayfs_umount,
-	.clone_paths = &overlayfs_clonepaths,
-	.destroy = &overlayfs_destroy,
-	.create = &overlayfs_create,
+/* overlay */
+static const struct bdev_ops ovl_ops = {
+	.detect = &ovl_detect,
+	.mount = &ovl_mount,
+	.umount = &ovl_umount,
+	.clone_paths = &ovl_clonepaths,
+	.destroy = &ovl_destroy,
+	.create = &ovl_create,
 	.can_snapshot = true,
 	.can_backup = true,
 };
@@ -3403,7 +2963,7 @@ static const struct bdev_type bdevs[] = {
 	{.name = "btrfs", .ops = &btrfs_ops,},
 	{.name = "dir", .ops = &dir_ops,},
 	{.name = "aufs", .ops = &aufs_ops,},
-	{.name = "overlayfs", .ops = &overlayfs_ops,},
+	{.name = "overlayfs", .ops = &ovl_ops,},
 	{.name = "loop", .ops = &loop_ops,},
 	{.name = "nbd", .ops = &nbd_ops,},
 };
@@ -3818,14 +3378,6 @@ struct bdev *bdev_create(const char *dest, const char *type,
 	return do_bdev_create(dest, type, cname, specs);
 }
 
-char *overlay_getlower(char *p)
-{
-	char *p1 = strchr(p, ':');
-	if (p1)
-		*p1 = '\0';
-	return p;
-}
-
 bool rootfs_is_blockdev(struct lxc_conf *conf)
 {
 	const struct bdev_type *q;

src/lxc/bdev.h → src/lxc/bdev/bdev.h

@@ -27,11 +27,11 @@
  * aufs, dir, raw, btrfs, overlayfs, aufs, lvm, loop, zfs, nbd (qcow2, raw, vdi, qed)
  */
 
-#include "config.h"
 #include <stdint.h>
 #include <lxc/lxccontainer.h>
 #include <sys/mount.h>
 
+#include "config.h"
 
 /* define constants if the kernel/glibc headers don't define them */
 #ifndef MS_DIRSYNC
@@ -97,8 +97,6 @@ struct bdev {
 	int nbd_idx;
 };
 
-char *overlay_getlower(char *p);
-
 bool bdev_is_dir(struct lxc_conf *conf, const char *path);
 bool bdev_can_backup(struct lxc_conf *conf);
 

src/lxc/bdev/overlay.c

+/*
+ * lxc: linux Container library
+ *
+ * (C) Copyright IBM Corp. 2007, 2008
+ *
+ * Authors:
+ * Daniel Lezcano <daniel.lezcano at free.fr>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#define _GNU_SOURCE
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "bdev.h"
+#include "conf.h"
+#include "confile.h"
+#include "log.h"
+#include "lxccontainer.h"
+#include "overlay.h"
+#include "utils.h"
+
+lxc_log_define(overlay, lxc);
+
+static char *ovl_name;
+
+struct ovl_rsync_data {
+	struct bdev *orig;
+	struct bdev *new;
+};
+
+/* defined in lxccontainer.c: needs to become common helper */
+extern int do_rsync(const char *src, const char *dest);
+
+/* defined in lxccontainer.c: needs to become common helper */
+extern char *dir_new_path(char *src, const char *oldname, const char *name,
+			  const char *oldpath, const char *lxcpath);
+
+static char *ovl_detect_name(void);
+static int ovl_do_rsync(struct bdev *orig, struct bdev *new, struct lxc_conf *conf);
+static int ovl_rsync(struct ovl_rsync_data *data);
+static int ovl_rsync_wrapper(void *data);
+
+int ovl_clonepaths(struct bdev *orig, struct bdev *new, const char *oldname,
+		   const char *cname, const char *oldpath, const char *lxcpath,
+		   int snap, uint64_t newsize, struct lxc_conf *conf)
+{
+	if (!snap) {
+		ERROR("overlayfs is only for snapshot clones");
+		return -22;
+	}
+
+	if (!orig->src || !orig->dest)
+		return -1;
+
+	new->dest = dir_new_path(orig->dest, oldname, cname, oldpath, lxcpath);
+	if (!new->dest)
+		return -1;
+	if (mkdir_p(new->dest, 0755) < 0)
+		return -1;
+
+	if (am_unpriv() && chown_mapped_root(new->dest, conf) < 0)
+		WARN("Failed to update ownership of %s", new->dest);
+
+	if (strcmp(orig->type, "dir") == 0) {
+		char *delta, *lastslash;
+		char *work;
+		int ret, len, lastslashidx;
+
+		/*
+		 * if we have
+		 *	/var/lib/lxc/c2/rootfs
+		 * then delta will be
+		 *	/var/lib/lxc/c2/delta0
+		 */
+		lastslash = strrchr(new->dest, '/');
+		if (!lastslash)
+			return -22;
+		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);
+			return -1;
+		}
+		if (am_unpriv() && chown_mapped_root(delta, conf) < 0)
+			WARN("Failed to update ownership of %s", delta);
+
+		/*
+		 * Make workdir for overlayfs.v22 or higher:
+		 * The workdir will be
+		 *	/var/lib/lxc/c2/olwork
+		 * and is used to prepare files before they are atomically
+		 * switched to the overlay destination. Workdirs need to be on
+		 * the same filesystem as the upperdir so it's OK for it to be
+		 * empty.
+		 */
+		work = malloc(lastslashidx + 7);
+		if (!work) {
+			free(delta);
+			return -1;
+		}
+		strncpy(work, new->dest, lastslashidx + 1);
+		strcpy(work + lastslashidx, "olwork");
+		if (mkdir(work, 0755) < 0) {
+			SYSERROR("error: mkdir %s", work);
+			free(delta);
+			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);
+		if (!new->src) {
+			free(delta);
+			return -ENOMEM;
+		}
+		ret = snprintf(new->src, len, "overlayfs:%s:%s", orig->src, delta);
+		free(delta);
+		if (ret < 0 || ret >= len)
+			return -ENOMEM;
+	} else if (strcmp(orig->type, "overlayfs") == 0) {
+		/*
+		 * What exactly do we want to do here?  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, *work;
+		char *lastslash;
+		int len, ret, lastslashidx;
+		if (!(osrc = strdup(orig->src)))
+			return -22;
+		nsrc = strchr(osrc, ':') + 1;
+		if (nsrc != osrc + 10 || (odelta = strchr(nsrc, ':')) == NULL) {
+			free(osrc);
+			return -22;
+		}
+		*odelta = '\0';
+		odelta++;
+		ndelta = dir_new_path(odelta, oldname, cname, oldpath, lxcpath);
+		if (!ndelta) {
+			free(osrc);
+			return -ENOMEM;
+		}
+		if ((ret = mkdir(ndelta, 0755)) < 0 && errno != EEXIST) {
+			SYSERROR("error: mkdir %s", ndelta);
+			free(osrc);
+			free(ndelta);
+			return -1;
+		}
+		if (am_unpriv() && chown_mapped_root(ndelta, conf) < 0)
+			WARN("Failed to update ownership of %s", ndelta);
+
+		/*
+		 * make workdir for overlayfs.v22 or higher (see comment further
+		 * up)
+		 */
+		lastslash = strrchr(ndelta, '/');
+		if (!lastslash)
+			return -1;
+		lastslash++;
+		lastslashidx = lastslash - ndelta;
+
+		work = malloc(lastslashidx + 7);
+		if (!work)
+			return -1;
+		strncpy(work, ndelta, lastslashidx + 1);
+		strcpy(work + lastslashidx, "olwork");
+		if ((mkdir(work, 0755) < 0) && errno != EEXIST) {
+			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);
+
+		len = strlen(nsrc) + strlen(ndelta) + 12;
+		new->src = malloc(len);
+		if (!new->src) {
+			free(osrc);
+			free(ndelta);
+			return -ENOMEM;
+		}
+		ret = snprintf(new->src, len, "overlayfs:%s:%s", nsrc, ndelta);
+		free(osrc);
+		free(ndelta);
+		if (ret < 0 || ret >= len)
+			return -ENOMEM;
+
+		return ovl_do_rsync(orig, new, conf);
+	} else {
+		ERROR("overlayfs clone of %s container is not yet supported",
+		      orig->type);
+		/*
+		 * Note, supporting this will require ovl_mount supporting
+		 * mounting of the underlay. No big deal, just needs to be done.
+		 */
+		return -1;
+	}
+
+	return 0;
+}
+
+/*
+ * to say 'lxc-create -t ubuntu -n o1 -B overlayfs' means you want
+ * $lxcpath/$lxcname/rootfs to have the created container, while all
+ * changes after starting the container are written to
+ * $lxcpath/$lxcname/delta0
+ */
+int ovl_create(struct bdev *bdev, const char *dest, const char *n,
+			struct bdev_specs *specs)
+{
+	char *delta;
+	int ret, len = strlen(dest), newlen;
+
+	if (len < 8 || strcmp(dest + len - 7, "/rootfs") != 0)
+		return -1;
+
+	if (!(bdev->dest = strdup(dest))) {
+		ERROR("Out of memory");
+		return -1;
+	}
+
+	delta = alloca(strlen(dest) + 1);
+	strcpy(delta, dest);
+	strcpy(delta + len - 6, "delta0");
+
+	if (mkdir_p(delta, 0755) < 0) {
+		ERROR("Error creating %s", delta);
+		return -1;
+	}
+
+	// overlayfs:lower:upper
+	newlen = (2 * len) + strlen("overlayfs:") + 2;
+	bdev->src = malloc(newlen);
+	if (!bdev->src) {
+		ERROR("Out of memory");
+		return -1;
+	}
+	ret = snprintf(bdev->src, newlen, "overlayfs:%s:%s", dest, delta);
+	if (ret < 0 || ret >= newlen)
+		return -1;
+
+	if (mkdir_p(bdev->dest, 0755) < 0) {
+		ERROR("Error creating %s", bdev->dest);
+		return -1;
+	}
+
+	return 0;
+}
+
+int ovl_destroy(struct bdev *orig)
+{
+	char *upper;
+
+	if (strncmp(orig->src, "overlayfs:", 10) != 0)
+		return -22;
+	upper = strchr(orig->src + 10, ':');
+	if (!upper)
+		return -22;
+	upper++;
+	return lxc_rmdir_onedev(upper, NULL);
+}
+
+int ovl_detect(const char *path)
+{
+	if (strncmp(path, "overlayfs:", 10) == 0)
+		return 1; // take their word for it
+	return 0;
+}
+
+char *ovl_getlower(char *p)
+{
+	char *p1 = strchr(p, ':');
+	if (p1)
+		*p1 = '\0';
+	return p;
+}
+
+int ovl_mount(struct bdev *bdev)
+{
+	char *options, *dup, *lower, *upper;
+	char *options_work, *work, *lastslash;
+	int lastslashidx;
+	int len, len2;
+	unsigned long mntflags;
+	char *mntdata;
+	int ret, ret2;
+
+	if (strcmp(bdev->type, "overlayfs"))
+		return -22;
+	if (!bdev->src || !bdev->dest)
+		return -22;
+
+	if (!ovl_name)
+		ovl_name = ovl_detect_name();
+
+	/*
+	 * separately mount it first:
+	 * mount -t overlayfs * -oupperdir=${upper},lowerdir=${lower} lower dest
+	 */
+	dup = alloca(strlen(bdev->src) + 1);
+	strcpy(dup, bdev->src);
+	if (!(lower = strchr(dup, ':')))
+		return -22;
+	if (!(upper = strchr(++lower, ':')))
+		return -22;
+	*upper = '\0';
+	upper++;
+
+	// if delta doesn't yet exist, create it
+	if (mkdir_p(upper, 0755) < 0 && errno != EEXIST)
+		return -22;
+
+	/*
+	 * overlayfs.v22 or higher needs workdir option:
+	 * if upper is
+	 *	/var/lib/lxc/c2/delta0
+	 * then workdir is
+	 *	/var/lib/lxc/c2/olwork
+	 */
+	lastslash = strrchr(upper, '/');
+	if (!lastslash)
+		return -22;
+	lastslash++;
+	lastslashidx = lastslash - upper;
+
+	work = alloca(lastslashidx + 7);
+	strncpy(work, upper, lastslashidx + 7);
+	strcpy(work + lastslashidx, "olwork");
+
+	if (parse_mntopts(bdev->mntopts, &mntflags, &mntdata) < 0) {
+		free(mntdata);
+		return -22;
+	}
+
+	if (mkdir_p(work, 0755) < 0 && errno != EEXIST) {
+		free(mntdata);
+		return -22;
+	}
+
+	/*
+	 * TODO:
+	 * We should check whether bdev->src is a blockdev but for now only
+	 * support overlays of a basic directory
+	 */
+
+	if (mntdata) {
+		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 || ret2 < 0 || ret2 >= len2) {
+		free(mntdata);
+		return -1;
+	}
+
+	// mount without workdir option for overlayfs before v21
+	ret = mount(lower, bdev->dest, ovl_name, MS_MGC_VAL | mntflags, options);
+	if (ret < 0) {
+		INFO("overlayfs: error mounting %s onto %s options %s. retry with workdir",
+			lower, bdev->dest, options);
+
+		// retry with workdir option for overlayfs v22 and higher
+		ret = mount(lower, bdev->dest, ovl_name, 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);
+	}
+	return ret;
+}
+
+int ovl_umount(struct bdev *bdev)
+{
+	if (strcmp(bdev->type, "overlayfs"))
+		return -22;
+	if (!bdev->src || !bdev->dest)
+		return -22;
+	return umount(bdev->dest);
+}
+
+char *ovl_get_rootfs(const char *rootfs_path, size_t *rootfslen)
+{
+	char *rootfsdir = NULL;
+	char *s1 = NULL;
+	char *s2 = NULL;
+	char *s3 = NULL;
+
+	if (!rootfs_path || !rootfslen)
+		return NULL;
+
+	s1 = strdup(rootfs_path);
+	if (!s1)
+		return NULL;
+
+	if ((s2 = strstr(s1, ":/"))) {
+		s2 = s2 + 1;
+		if ((s3 = strstr(s2, ":/")))
+			*s3 = '\0';
+		rootfsdir = strdup(s2);
+		if (!rootfsdir) {
+			free(s1);
+			return NULL;
+		}
+	}
+
+	if (!rootfsdir)
+		rootfsdir = s1;
+	else
+		free(s1);
+
+	*rootfslen = strlen(rootfsdir);
+
+	return rootfsdir;
+}
+
+int ovl_mkdir(const struct mntent *mntent, const struct lxc_rootfs *rootfs,
+	      const char *lxc_name, const char *lxc_path)
+{
+	char lxcpath[MAXPATHLEN];
+	char *rootfsdir = NULL;
+	char *upperdir = NULL;
+	char *workdir = NULL;
+	char **opts = NULL;
+	int fret = -1;
+	int ret = 0;
+	size_t arrlen = 0;
+	size_t dirlen = 0;
+	size_t i;
+	size_t len = 0;
+	size_t rootfslen = 0;
+
+	if (!rootfs->path || !lxc_name || !lxc_path)
+		goto err;
+
+	opts = lxc_string_split(mntent->mnt_opts, ',');
+	if (opts)
+		arrlen = lxc_array_len((void **)opts);
+	else
+		goto err;
+
+	for (i = 0; i < arrlen; i++) {
+		if (strstr(opts[i], "upperdir=") && (strlen(opts[i]) > (len = strlen("upperdir="))))
+			upperdir = opts[i] + len;
+		else if (strstr(opts[i], "workdir=") && (strlen(opts[i]) > (len = strlen("workdir="))))
+			workdir = opts[i] + len;
+	}
+
+	ret = snprintf(lxcpath, MAXPATHLEN, "%s/%s", lxc_path, lxc_name);
+	if (ret < 0 || ret >= MAXPATHLEN)
+		goto err;
+
+	rootfsdir = ovl_get_rootfs(rootfs->path, &rootfslen);
+	if (!rootfsdir)
+		goto err;
+
+	dirlen = strlen(lxcpath);
+
+	/*
+	 * We neither allow users to create upperdirs and workdirs outside the
+	 * containerdir nor inside the rootfs. The latter might be debatable.
+	 */
+	if (upperdir)
+		if ((strncmp(upperdir, lxcpath, dirlen) == 0) && (strncmp(upperdir, rootfsdir, rootfslen) != 0))
+			if (mkdir_p(upperdir, 0755) < 0) {
+				WARN("Failed to create upperdir");
+			}
+
+	if (workdir)
+		if ((strncmp(workdir, lxcpath, dirlen) == 0) && (strncmp(workdir, rootfsdir, rootfslen) != 0))
+			if (mkdir_p(workdir, 0755) < 0) {
+				WARN("Failed to create workdir");
+			}
+
+	fret = 0;
+
+err:
+	free(rootfsdir);
+	lxc_free_array((void **)opts, free);
+	return fret;
+}
+
+/*
+ * To be called from lxcapi_clone() in lxccontainer.c: When we clone a container
+ * with overlay lxc.mount.entry entries we need to update absolute paths for
+ * upper- and workdir. This update is done in two locations:
+ * lxc_conf->unexpanded_config and lxc_conf->mount_list. Both updates are done
+ * independent of each other since lxc_conf->mountlist may container more mount
+ * entries (e.g. from other included files) than lxc_conf->unexpanded_config .
+ */
+int ovl_update_abs_paths(struct lxc_conf *lxc_conf, const char *lxc_path,
+			 const char *lxc_name, const char *newpath,
+			 const char *newname)
+{
+	char new_upper[MAXPATHLEN];
+	char new_work[MAXPATHLEN];
+	char old_upper[MAXPATHLEN];
+	char old_work[MAXPATHLEN];
+	char *cleanpath = NULL;
+	int i;
+	int fret = -1;
+	int ret = 0;
+	struct lxc_list *iterator;
+	const char *ovl_dirs[] = {"br", "upperdir", "workdir"};
+
+	cleanpath = strdup(newpath);
+	if (!cleanpath)
+		goto err;
+
+	remove_trailing_slashes(cleanpath);
+
+	/*
+	 * We have to update lxc_conf->unexpanded_config separately from
+	 * lxc_conf->mount_list.
+	 */
+	for (i = 0; i < sizeof(ovl_dirs) / sizeof(ovl_dirs[0]); i++) {
+		if (!clone_update_unexp_ovl_paths(lxc_conf, lxc_path, newpath,
+						  lxc_name, newname,
+						  ovl_dirs[i]))
+			goto err;
+	}
+
+	ret = snprintf(old_work, MAXPATHLEN, "workdir=%s/%s", lxc_path, lxc_name);
+	if (ret < 0 || ret >= MAXPATHLEN)
+		goto err;
+
+	ret = snprintf(new_work, MAXPATHLEN, "workdir=%s/%s", cleanpath, newname);
+	if (ret < 0 || ret >= MAXPATHLEN)
+		goto err;
+
+	lxc_list_for_each(iterator, &lxc_conf->mount_list) {
+		char *mnt_entry = NULL;
+		char *new_mnt_entry = NULL;
+		char *tmp = NULL;
+		char *tmp_mnt_entry = NULL;
+		mnt_entry = iterator->elem;
+
+		if (strstr(mnt_entry, "overlay"))
+			tmp = "upperdir";
+		else if (strstr(mnt_entry, "aufs"))
+			tmp = "br";
+
+		if (!tmp)
+			continue;
+
+		ret = snprintf(old_upper, MAXPATHLEN, "%s=%s/%s", tmp, lxc_path, lxc_name);
+		if (ret < 0 || ret >= MAXPATHLEN)
+			goto err;
+
+		ret = snprintf(new_upper, MAXPATHLEN, "%s=%s/%s", tmp, cleanpath, newname);
+		if (ret < 0 || ret >= MAXPATHLEN)
+			goto err;
+
+		if (strstr(mnt_entry, old_upper)) {
+			tmp_mnt_entry = lxc_string_replace(old_upper, new_upper, mnt_entry);
+		}
+
+		if (strstr(mnt_entry, old_work)) {
+			if (tmp_mnt_entry)
+				new_mnt_entry = lxc_string_replace(old_work, new_work, tmp_mnt_entry);
+			else
+				new_mnt_entry = lxc_string_replace(old_work, new_work, mnt_entry);
+		}
+
+		if (new_mnt_entry) {
+			free(iterator->elem);
+			iterator->elem = strdup(new_mnt_entry);
+		} else if (tmp_mnt_entry) {
+			free(iterator->elem);
+			iterator->elem = strdup(tmp_mnt_entry);
+		}
+
+		free(new_mnt_entry);
+		free(tmp_mnt_entry);
+	}
+
+	fret = 0;
+err:
+	free(cleanpath);
+	return fret;
+}
+
+static int ovl_rsync(struct ovl_rsync_data *data)
+{
+	int ret;
+
+	if (setgid(0) < 0) {
+		ERROR("Failed to setgid to 0");
+		return -1;
+	}
+	if (setgroups(0, NULL) < 0)
+		WARN("Failed to clear groups");
+	if (setuid(0) < 0) {
+		ERROR("Failed to setuid to 0");
+		return -1;
+	}
+
+	if (unshare(CLONE_NEWNS) < 0) {
+		SYSERROR("Unable to unshare mounts ns");
+		return -1;
+	}
+	if (detect_shared_rootfs()) {
+		if (mount(NULL, "/", NULL, MS_SLAVE|MS_REC, NULL)) {
+			SYSERROR("Failed to make / rslave");
+			ERROR("Continuing...");
+		}
+	}
+	if (ovl_mount(data->orig) < 0) {
+		ERROR("Failed mounting original container fs");
+		return -1;
+	}
+	if (ovl_mount(data->new) < 0) {
+		ERROR("Failed mounting new container fs");
+		return -1;
+	}
+	ret = do_rsync(data->orig->dest, data->new->dest);
+
+	ovl_umount(data->new);
+	ovl_umount(data->orig);
+
+	if (ret < 0) {
+		ERROR("rsyncing %s to %s", data->orig->dest, data->new->dest);
+		return -1;
+	}
+
+	return 0;
+}
+
+static char *ovl_detect_name(void)
+{
+	char *v = "overlayfs";
+	char *line = NULL;
+	size_t len = 0;
+	FILE *f = fopen("/proc/filesystems", "r");
+	if (!f)
+		return v;
+
+	while (getline(&line, &len, f) != -1) {
+		if (strcmp(line, "nodev\toverlay\n") == 0) {
+			v = "overlay";
+			break;
+		}
+	}
+
+	fclose(f);
+	free(line);
+	return v;
+}
+
+static int ovl_do_rsync(struct bdev *orig, struct bdev *new, struct lxc_conf *conf)
+{
+	int ret = -1;
+	struct ovl_rsync_data rdata;
+
+	rdata.orig = orig;
+	rdata.new = new;
+	if (am_unpriv())
+		ret = userns_exec_1(conf, ovl_rsync_wrapper, &rdata);
+	else
+		ret = ovl_rsync(&rdata);
+	if (ret)
+		ERROR("copying overlayfs delta");
+
+	return ret;
+}
+
+static int ovl_rsync_wrapper(void *data)
+{
+	struct ovl_rsync_data *arg = data;
+	return ovl_rsync(arg);
+}
+

src/lxc/bdev/overlay.h

+/*
+ * lxc: linux Container library
+ *
+ * (C) Copyright IBM Corp. 2007, 2008
+ *
+ * Authors:
+ * Daniel Lezcano <daniel.lezcano at free.fr>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef __LXC_OVERLAY_H
+#define __LXC_OVERLAY_H
+
+#include <grp.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <sys/types.h>
+
+#if IS_BIONIC
+#include <../include/lxcmntent.h>
+#else
+#include <mntent.h>
+#endif
+
+/* defined in bdev.h */
+struct bdev;
+
+/* defined in lxccontainer.h */
+struct bdev_specs;
+
+/* defined conf.h */
+struct lxc_conf;
+
+/* defined in conf.h */
+struct lxc_rootfs;
+
+/*
+ * Functions associated with an overlay bdev struct.
+ */
+int ovl_clonepaths(struct bdev *orig, struct bdev *new, const char *oldname,
+		   const char *cname, const char *oldpath, const char *lxcpath,
+		   int snap, uint64_t newsize, struct lxc_conf *conf);
+int ovl_create(struct bdev *bdev, const char *dest, const char *n,
+	       struct bdev_specs *specs);
+int ovl_destroy(struct bdev *orig);
+int ovl_detect(const char *path);
+int ovl_mount(struct bdev *bdev);
+int ovl_umount(struct bdev *bdev);
+
+/*
+ * To be called from lxcapi_clone() in lxccontainer.c: When we clone a container
+ * with overlay lxc.mount.entry entries we need to update absolute paths for
+ * upper- and workdir. This update is done in two locations:
+ * lxc_conf->unexpanded_config and lxc_conf->mount_list. Both updates are done
+ * independent of each other since lxc_conf->mountlist may container more mount
+ * entries (e.g. from other included files) than lxc_conf->unexpanded_config .
+ */
+int ovl_update_abs_paths(struct lxc_conf *lxc_conf, const char *lxc_path,
+			 const char *lxc_name, const char *newpath,
+			 const char *newname);
+
+/*
+ * To be called from functions in lxccontainer.c: Get lower directory for
+ * overlay rootfs.
+ */
+char *ovl_getlower(char *p);
+
+/*
+ * Get rootfs path for overlay backed containers. Allocated memory must be freed
+ * by caller.
+ */
+char *ovl_get_rootfs(const char *rootfs_path, size_t *rootfslen);
+
+/*
+ * Create upper- and workdirs for overlay mounts.
+ */
+int ovl_mkdir(const struct mntent *mntent, const struct lxc_rootfs *rootfs,
+	      const char *lxc_name, const char *lxc_path);
+
+#endif /* __LXC_OVERLAY_H */

src/lxc/cgfs.c

@@ -43,7 +43,7 @@
 #include "list.h"
 #include "conf.h"
 #include "utils.h"
-#include "bdev.h"
+#include "bdev/bdev.h"
 #include "log.h"
 #include "cgroup.h"
 #include "start.h"

src/lxc/cgmanager.c

@@ -46,7 +46,7 @@
 #include "list.h"
 #include "conf.h"
 #include "utils.h"
-#include "bdev.h"
+#include "bdev/bdev.h"
 #include "log.h"
 #include "cgroup.h"
 #include "start.h"

src/lxc/conf.c

@@ -71,7 +71,8 @@
 #include "conf.h"
 #include "log.h"
 #include "caps.h"       /* for lxc_caps_last_cap() */
-#include "bdev.h"
+#include "bdev/bdev.h"
+#include "bdev/overlay.h"
 #include "cgroup.h"
 #include "lxclock.h"
 #include "namespace.h"
@@ -1815,107 +1816,6 @@ static void cull_mntent_opt(struct mntent *mntent)
 	}
 }
 
-static char *ovl_get_rootfs_dir(const char *rootfs_path, size_t *rootfslen)
-{
-	char *rootfsdir = NULL;
-	char *s1 = NULL;
-	char *s2 = NULL;
-	char *s3 = NULL;
-
-	if (!rootfs_path || !rootfslen)
-		return NULL;
-
-	s1 = strdup(rootfs_path);
-	if (!s1)
-		return NULL;
-
-	if ((s2 = strstr(s1, ":/"))) {
-		s2 = s2 + 1;
-		if ((s3 = strstr(s2, ":/")))
-			*s3 = '\0';
-		rootfsdir = strdup(s2);
-		if (!rootfsdir) {
-			free(s1);
-			return NULL;
-		}
-	}
-
-	if (!rootfsdir)
-		rootfsdir = s1;
-	else
-		free(s1);
-
-	*rootfslen = strlen(rootfsdir);
-
-	return rootfsdir;
-}
-
-static int mount_entry_create_overlay_dirs(const struct mntent *mntent,
-					   const struct lxc_rootfs *rootfs,
-					   const char *lxc_name,
-					   const char *lxc_path)
-{
-	char lxcpath[MAXPATHLEN];
-	char *rootfsdir = NULL;
-	char *upperdir = NULL;
-	char *workdir = NULL;
-	char **opts = NULL;
-	int fret = -1;
-	int ret = 0;
-	size_t arrlen = 0;
-	size_t dirlen = 0;
-	size_t i;
-	size_t len = 0;
-	size_t rootfslen = 0;
-
-	if (!rootfs->path || !lxc_name || !lxc_path)
-		goto err;
-
-	opts = lxc_string_split(mntent->mnt_opts, ',');
-	if (opts)
-		arrlen = lxc_array_len((void **)opts);
-	else
-		goto err;
-
-	for (i = 0; i < arrlen; i++) {
-		if (strstr(opts[i], "upperdir=") && (strlen(opts[i]) > (len = strlen("upperdir="))))
-			upperdir = opts[i] + len;
-		else if (strstr(opts[i], "workdir=") && (strlen(opts[i]) > (len = strlen("workdir="))))
-			workdir = opts[i] + len;
-	}
-
-	ret = snprintf(lxcpath, MAXPATHLEN, "%s/%s", lxc_path, lxc_name);
-	if (ret < 0 || ret >= MAXPATHLEN)
-		goto err;
-
-	rootfsdir = ovl_get_rootfs_dir(rootfs->path, &rootfslen);
-	if (!rootfsdir)
-		goto err;
-
-	dirlen = strlen(lxcpath);
-
-	/* We neither allow users to create upperdirs and workdirs outside the
-	 * containerdir nor inside the rootfs. The latter might be debatable. */
-	if (upperdir)
-		if ((strncmp(upperdir, lxcpath, dirlen) == 0) && (strncmp(upperdir, rootfsdir, rootfslen) != 0))
-			if (mkdir_p(upperdir, 0755) < 0) {
-				WARN("Failed to create upperdir");
-			}
-
-	if (workdir)
-		if ((strncmp(workdir, lxcpath, dirlen) == 0) && (strncmp(workdir, rootfsdir, rootfslen) != 0))
-			if (mkdir_p(workdir, 0755) < 0) {
-				WARN("Failed to create workdir");
-			}
-
-	fret = 0;
-
-err:
-	free(rootfsdir);
-	lxc_free_array((void **)opts, free);
-	return fret;
-}
-
 static int mount_entry_create_aufs_dirs(const struct mntent *mntent,
 					const struct lxc_rootfs *rootfs,
 					const char *lxc_name,
@@ -1958,7 +1858,7 @@ static int mount_entry_create_aufs_dirs(const struct mntent *mntent,
 	if (ret < 0 || ret >= MAXPATHLEN)
 		goto err;
 
-	rootfsdir = ovl_get_rootfs_dir(rootfs->path, &rootfslen);
+	rootfsdir = ovl_get_rootfs(rootfs->path, &rootfslen);
 	if (!rootfsdir)
 		goto err;
 
@@ -1987,7 +1887,7 @@ static int mount_entry_create_dir_file(const struct mntent *mntent,
 	FILE *pathfile = NULL;
 
 	if (strncmp(mntent->mnt_type, "overlay", 7) == 0) {
-		if (mount_entry_create_overlay_dirs(mntent, rootfs, lxc_name, lxc_path) < 0)
+		if (ovl_mkdir(mntent, rootfs, lxc_name, lxc_path) < 0)
 			return -1;
 	} else if (strncmp(mntent->mnt_type, "aufs", 4) == 0) {
 		if (mount_entry_create_aufs_dirs(mntent, rootfs, lxc_name, lxc_path) < 0)

src/lxc/criu.c

@@ -34,7 +34,7 @@
 
 #include "config.h"
 
-#include "bdev.h"
+#include "bdev/bdev.h"
 #include "cgroup.h"
 #include "conf.h"
 #include "commands.h"

src/lxc/lxc_copy.c

@@ -44,7 +44,7 @@
 #include "conf.h"
 #include "state.h"
 #include "utils.h"
-#include "bdev.h"
+#include "bdev/bdev.h"
 
 #ifndef HAVE_GETSUBOPT
 #include <../include/getsubopt.h>

src/lxc/lxc_create.c

@@ -29,7 +29,7 @@
 
 #include "lxc.h"
 #include "log.h"
-#include "bdev.h"
+#include "bdev/bdev.h"
 #include "arguments.h"
 #include "utils.h"
 

src/lxc/lxc_snapshot.c

@@ -29,7 +29,7 @@
 
 #include "lxc.h"
 #include "log.h"
-#include "bdev.h"
+#include "bdev/bdev.h"
 #include "arguments.h"
 #include "utils.h"
 

src/lxc/lxccontainer.c

@@ -19,48 +19,46 @@
  */
 
 #define _GNU_SOURCE
-#include <sys/mman.h>
 #include <assert.h>
-#include <stdarg.h>
-#include <pthread.h>
-#include <unistd.h>
-#include <sys/types.h>
-#include <sys/wait.h>
-#include <sys/mount.h>
+#include <dirent.h>
 #include <errno.h>
 #include <fcntl.h>
-#include <sched.h>
-#include <dirent.h>
-#include <sched.h>
-#include <arpa/inet.h>
+#include <grp.h>
 #include <libgen.h>
+#include <pthread.h>
+#include <sched.h>
+#include <stdarg.h>
 #include <stdint.h>
-#include <grp.h>
 #include <stdio.h>
+#include <unistd.h>
+#include <arpa/inet.h>
+#include <sys/mman.h>
+#include <sys/mount.h>
 #include <sys/syscall.h>
+#include <sys/types.h>
+#include <sys/wait.h>
 
-#include <lxc/lxccontainer.h>
-#include <lxc/version.h>
-#include <lxc/network.h>
-
-#include "config.h"
-#include "lxc.h"
-#include "state.h"
+#include "attach.h"
+#include "bdev/bdev.h"
+#include "bdev/overlay.h"
+#include "cgroup.h"
 #include "conf.h"
+#include "config.h"
+#include "commands.h"
 #include "confile.h"
 #include "console.h"
-#include "cgroup.h"
-#include "commands.h"
 #include "criu.h"
 #include "log.h"
-#include "bdev.h"
-#include "utils.h"
-#include "attach.h"
+#include "lxc.h"
+#include "lxccontainer.h"
+#include "lxclock.h"
 #include "monitor.h"
 #include "namespace.h"
 #include "network.h"
-#include "lxclock.h"
 #include "sync.h"
+#include "state.h"
+#include "utils.h"
+#include "version.h"
 
 #if HAVE_IFADDRS_H
 #include <ifaddrs.h>
@@ -1095,9 +1093,9 @@ static bool create_run_template(struct lxc_container *c, char *tpath, bool need_
 		 * the template
 		 */
 		if (strncmp(src, "overlayfs:", 10) == 0)
-			src = overlay_getlower(src+10);
+			src = ovl_getlower(src+10);
 		if (strncmp(src, "aufs:", 5) == 0)
-			src = overlay_getlower(src+5);
+			src = ovl_getlower(src+5);
 
 		bdev = bdev_init(c->lxc_conf, src, c->lxc_conf->rootfs.mount, NULL);
 		if (!bdev) {
@@ -2997,102 +2995,6 @@ static int create_file_dirname(char *path, struct lxc_conf *conf)
 	return ret;
 }
 
-/* When we clone a container with overlay lxc.mount.entry entries we need to
-*  update absolute paths for upper- and workdir. This update is done in two
-*  locations: lxc_conf->unexpanded_config and lxc_conf->mount_list. Both updates
-*  are done independent of each other since lxc_conf->mountlist may container
-*  more mount entries (e.g. from other included files) than
-*  lxc_conf->unexpanded_config . */
-static int update_ovl_paths(struct lxc_conf *lxc_conf, const char *lxc_path,
-			    const char *lxc_name, const char *newpath,
-			    const char *newname)
-{
-	char new_upper[MAXPATHLEN];
-	char new_work[MAXPATHLEN];
-	char old_upper[MAXPATHLEN];
-	char old_work[MAXPATHLEN];
-	char *cleanpath = NULL;
-	int i;
-	int fret = -1;
-	int ret = 0;
-	struct lxc_list *iterator;
-	const char *ovl_dirs[] = {"br", "upperdir", "workdir"};
-
-	cleanpath = strdup(newpath);
-	if (!cleanpath)
-		goto err;
-
-	remove_trailing_slashes(cleanpath);
-
-	/* We have to update lxc_conf->unexpanded_config separately from
-	*  lxc_conf->mount_list. */
-	for (i = 0; i < sizeof(ovl_dirs) / sizeof(ovl_dirs[0]); i++) {
-		if (!clone_update_unexp_ovl_paths(lxc_conf, lxc_path, newpath,
-						  lxc_name, newname,
-						  ovl_dirs[i]))
-			goto err;
-	}
-
-	ret = snprintf(old_work, MAXPATHLEN, "workdir=%s/%s", lxc_path, lxc_name);
-	if (ret < 0 || ret >= MAXPATHLEN)
-		goto err;
-
-	ret = snprintf(new_work, MAXPATHLEN, "workdir=%s/%s", cleanpath, newname);
-	if (ret < 0 || ret >= MAXPATHLEN)
-		goto err;
-
-	lxc_list_for_each(iterator, &lxc_conf->mount_list) {
-		char *mnt_entry = NULL;
-		char *new_mnt_entry = NULL;
-		char *tmp = NULL;
-		char *tmp_mnt_entry = NULL;
-		mnt_entry = iterator->elem;
-
-		if (strstr(mnt_entry, "overlay"))
-			tmp = "upperdir";
-		else if (strstr(mnt_entry, "aufs"))
-			tmp = "br";
-
-		if (!tmp)
-			continue;
-
-		ret = snprintf(old_upper, MAXPATHLEN, "%s=%s/%s", tmp, lxc_path, lxc_name);
-		if (ret < 0 || ret >= MAXPATHLEN)
-			goto err;
-
-		ret = snprintf(new_upper, MAXPATHLEN, "%s=%s/%s", tmp, cleanpath, newname);
-		if (ret < 0 || ret >= MAXPATHLEN)
-			goto err;
-
-		if (strstr(mnt_entry, old_upper)) {
-			tmp_mnt_entry = lxc_string_replace(old_upper, new_upper, mnt_entry);
-		}
-
-		if (strstr(mnt_entry, old_work)) {
-			if (tmp_mnt_entry)
-				new_mnt_entry = lxc_string_replace(old_work, new_work, tmp_mnt_entry);
-			else
-				new_mnt_entry = lxc_string_replace(old_work, new_work, mnt_entry);
-		}
-
-		if (new_mnt_entry) {
-			free(iterator->elem);
-			iterator->elem = strdup(new_mnt_entry);
-		} else if (tmp_mnt_entry) {
-			free(iterator->elem);
-			iterator->elem = strdup(tmp_mnt_entry);
-		}
-
-		free(new_mnt_entry);
-		free(tmp_mnt_entry);
-	}
-
-	fret = 0;
-err:
-	free(cleanpath);
-	return fret;
-}
-
 static struct lxc_container *do_lxcapi_clone(struct lxc_container *c, const char *newname,
 		const char *lxcpath, int flags,
 		const char *bdevtype, const char *bdevdata, uint64_t newsize,
@@ -3223,7 +3125,7 @@ static struct lxc_container *do_lxcapi_clone(struct lxc_container *c, const char
 	}
 
 	// update absolute paths for overlay mount directories
-	if (update_ovl_paths(c2->lxc_conf, c->config_path, c->name, lxcpath, newname) < 0)
+	if (ovl_update_abs_paths(c2->lxc_conf, c->config_path, c->name, lxcpath, newname) < 0)
 		goto out;
 
 	// We've now successfully created c2's storage, so clear it out if we

src/lxc/start.c

@@ -69,7 +69,7 @@
 #include "namespace.h"
 #include "lxcseccomp.h"
 #include "caps.h"
-#include "bdev.h"
+#include "bdev/bdev.h"
 #include "lsm/lsm.h"
 #include "lxclock.h"