criu: introduce LUO image backend

Documentation/criu.txt

@@ -85,6 +85,15 @@ The following levels are available:
     Use 'path' as a parent directory where to look for sets of image files.
     This option makes sense in case of incremental dumps.
 
+*--luo-session* 'id'::
+    Create a Live Update Orchestrator session named 'id', and use it to store
+    images.
+    This will disable writing images to files.
+
+*--luo-session-fd* 'fd'::
+    Use 'fd' as the Live Update Orchestrator session to store images into.
+    This will disable writing images to files.
+
 *-W*, *--work-dir* 'dir'::
     Use directory 'dir' for putting logs, pidfiles and statistics. If not
     specified, 'path' from *-D* option is taken.

criu/Makefile.crtools

@@ -38,6 +38,7 @@ obj-y			+= kerndat.o
 obj-y			+= libnetlink.o
 obj-y			+= log.o
 obj-y			+= lsm.o
+obj-y			+= luo.o
 obj-y			+= mem.o
 obj-y			+= memfd.o
 obj-y			+= mount.o

criu/config.c

@@ -432,6 +432,7 @@ void init_opts(void)
 	opts.file_validation_method = FILE_VALIDATION_DEFAULT;
 	opts.network_lock_method = NETWORK_LOCK_DEFAULT;
 	opts.ghost_fiemap = FIEMAP_DEFAULT;
+	opts.luo_session_fd = -1;
 }
 
 bool deprecated_ok(char *what)
@@ -701,6 +702,8 @@ int parse_options(int argc, char **argv, bool *usage_error, bool *has_exec_cmd,
 		BOOL_OPT("skip-file-rwx-check", &opts.skip_file_rwx_check),
 		{ "lsm-mount-context", required_argument, 0, 1099 },
 		{ "network-lock", required_argument, 0, 1100 },
+		{ "luo-session", required_argument, 0, 1101 },
+		{ "luo-session-fd", required_argument, 0, 1102 },
 		BOOL_OPT("mntns-compat-mode", &opts.mntns_compat_mode),
 		BOOL_OPT("unprivileged", &opts.unprivileged),
 		BOOL_OPT("ghost-fiemap", &opts.ghost_fiemap),
@@ -1045,6 +1048,24 @@ int parse_options(int argc, char **argv, bool *usage_error, bool *has_exec_cmd,
 				return 1;
 			}
 			break;
+		case 1101:
+			if (opts.use_luo) {
+				pr_err("--luo-session or --luo-session-id was supplied multiple times.\n");
+				return 1;
+			}
+			SET_CHAR_OPTS(luo_session, optarg);
+			opts.use_luo = true;
+			break;
+		case 1102:
+			if (sscanf(optarg, "%d", &opts.luo_session_fd) != 1) {
+				pr_err("Unable to parse a value of --luo-session-fd\n");
+				return 1;
+			} else if (opts.use_luo) {
+				pr_err("--luo-session or --luo-session-id was supplied multiple times.\n");
+				return 1;
+			}
+			opts.use_luo = true;
+			break;
 		case 'V':
 			pr_msg("Version: %s\n", CRIU_VERSION);
 			if (strcmp(CRIU_GITID, "0"))

criu/cr-dump.c

@@ -88,6 +88,7 @@
 #include "asm/dump.h"
 #include "timer.h"
 #include "sigact.h"
+#include "luo.h"
 
 /*
  * Architectures can overwrite this function to restore register sets that
@@ -2125,11 +2126,21 @@ static int cr_dump_finish(int ret)
 			pr_info("fault: CRIU dump crashed!\n");
 			abort();
 		}
+		if (opts.use_luo && opts.luo_session)
+			luo_session_finish();
 		pr_err("Dumping FAILED.\n");
 	} else {
 		write_stats(DUMP_STATS);
 		pr_info("Dumping finished successfully\n");
+		/*
+		 * LUO will only preserve session file descriptors that were open
+		 * when kexec occurs, so we literally freeze in place.
+		 */
+		if (opts.use_luo && opts.luo_session)
+			luo_session_hang();
 	}
+
+
 	return post_dump_ret ?: (ret != 0);
 }
 
@@ -2196,6 +2207,11 @@ int cr_dump_tasks(pid_t pid)
 			goto err;
 	}
 
+	if (opts.use_luo && opts.luo_session) {
+		if (luo_session_init(opts.luo_session))
+			goto err;
+	}
+
 	if (connect_to_page_server_to_send() < 0)
 		goto err;
 

criu/cr-restore.c

@@ -81,6 +81,7 @@
 #include "bpfmap.h"
 #include "apparmor.h"
 #include "pidfd.h"
+#include "luo.h"
 
 #include "parasite-syscall.h"
 #include "files-reg.h"
@@ -2403,6 +2404,11 @@ int cr_restore_tasks(void)
 	if (fdstore_init())
 		return -1;
 
+	if (opts.use_luo && opts.luo_session) {
+		if (luo_session_open(opts.luo_session))
+			return -1;
+	}
+
 	/*
 	 * For the AMDGPU plugin, its parallel restore feature needs to use fdstore to store
 	 * its socket file descriptor. This allows the main process and the target process to
@@ -2431,6 +2437,10 @@ int cr_restore_tasks(void)
 clean_cgroup:
 	fini_cgroup();
 err:
+	if (opts.use_luo) {
+		luo_session_finish();
+	}
+
 	cr_plugin_fini(CR_PLUGIN_STAGE__RESTORE, ret);
 	return ret;
 }

criu/crtools.c

@@ -408,6 +408,10 @@ int main(int argc, char *argv[], char *envp[])
 	       "     --pidfile FILE     write root task, service or page-server pid to FILE\n"
 	       "  -W|--work-dir DIR     directory to cd and write logs/pidfiles/stats to\n"
 	       "                        (if not specified, value of --images-dir is used)\n"
+	       "     --luo-session NAME liveupdate session ID to write images to\n"
+	       "                        if specified, image files will not be written\n"
+	       "     --luo-session-fd N liveupdate session file descriptor to write images to \n"
+	       "                        if specified, image files will not be written\n"
 	       "     --cpu-cap [CAP]    CPU capabilities to write/check. CAP is comma-separated\n"
 	       "                        list of: cpu, fpu, all, ins, none. To disable\n"
 	       "                        a capability, use ^CAP. Empty argument implies all\n"

criu/image.c

@@ -19,6 +19,7 @@
 #include "proc_parse.h"
 #include "img-streamer.h"
 #include "namespaces.h"
+#include "luo.h"
 
 bool ns_per_id = false;
 bool img_common_magic = true;
@@ -608,6 +609,9 @@ static int do_open_image(struct cr_img *img, int dfd, int type, unsigned long of
 	if (opts.stream && !(oflags & O_FORCE_LOCAL)) {
 		ret = img_streamer_open(path, flags);
 		errno = EIO; /* errno value is meaningless, only the ret value is meaningful */
+	} else if (opts.use_luo && !(oflags & O_FORCE_LOCAL)) {
+		img->path = xstrdup(path);
+		ret = luo_image_open(img, flags);
 	} else if (root_ns_mask & CLONE_NEWUSER && type == CR_FD_PAGES && oflags & O_RDWR) {
 		/*
 		 * For pages images dedup we need to open images read-write on
@@ -693,6 +697,9 @@ void close_image(struct cr_img *img)
 		 */
 		unlinkat(get_service_fd(IMG_FD_OFF), img->path, 0);
 		xfree(img->path);
+	} else if (opts.use_luo && (img->oflags & O_WRONLY) && !(img->oflags & O_FORCE_LOCAL)) {
+		luo_image_close(img);
+		xfree(img->path);
 	} else if (!empty_image(img))
 		bclose(&img->_x);
 

criu/include/cr_options.h

@@ -195,6 +195,10 @@ struct cr_options {
 	int skip_file_rwx_check;
 	int allow_uprobes;
 
+	bool use_luo;
+	char *luo_session;
+	int luo_session_fd;
+
 	/*
 	 * When we scheduler for removal some functionality we first
 	 * deprecate it and it sits in criu for some time. By default