[PATCH RFC 2/3] lxc: Including CRIU functions and functions to support C/R.
Julio Faracco
jcfaracco at gmail.com
Sat Feb 27 04:06:34 UTC 2021
This patch adds the source code of helper functions into files
lxc_criu.{h,c} to support LXC checkpoint/restore using CRIU binary. To save
container state, LXC follows the same pattern of QEMU and libxl using a file
with a header with metadata, but as CRIU saves multiple files, it needs to
inserted in a unique file using a type of compression. Using TAR for
instance.
Signed-off-by: Julio Faracco <jcfaracco at gmail.com>
---
src/lxc/lxc_criu.c | 405 ++++++++++++++++++++++++++++++++++++++++++++
src/lxc/lxc_criu.h | 50 ++++++
src/lxc/meson.build | 2 +
3 files changed, 457 insertions(+)
create mode 100644 src/lxc/lxc_criu.c
create mode 100644 src/lxc/lxc_criu.h
diff --git a/src/lxc/lxc_criu.c b/src/lxc/lxc_criu.c
new file mode 100644
index 0000000000..a82bd5ffde
--- /dev/null
+++ b/src/lxc/lxc_criu.c
@@ -0,0 +1,405 @@
+/*
+ * lxc_criu.c: wrapper functions for CRIU C API to be used for lxc migration
+ *
+ * Copyright (c) 2021 Red Hat, Inc.
+ *
+ * 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, see
+ * <http://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <sys/mount.h>
+
+#include "virobject.h"
+#include "virerror.h"
+#include "virlog.h"
+#include "virfile.h"
+#include "vircommand.h"
+#include "virstring.h"
+#include "viralloc.h"
+#include "virutil.h"
+
+#include "lxc_domain.h"
+#include "lxc_driver.h"
+#include "lxc_criu.h"
+
+#define VIR_FROM_THIS VIR_FROM_LXC
+
+VIR_LOG_INIT("lxc.lxc_criu");
+
+#if WITH_CRIU
+typedef enum {
+ LXC_SAVE_FORMAT_RAW = 0,
+ LXC_SAVE_FORMAT_GZIP = 1,
+ LXC_SAVE_FORMAT_BZIP2 = 2,
+ LXC_SAVE_FORMAT_XZ = 3,
+ LXC_SAVE_FORMAT_LZOP = 4,
+
+ LXC_SAVE_FORMAT_LAST
+} virLXCSaveFormat;
+
+VIR_ENUM_DECL(lxcSaveCompression);
+VIR_ENUM_IMPL(lxcSaveCompression,
+ LXC_SAVE_FORMAT_LAST,
+ "raw",
+ "gzip",
+ "bzip2",
+ "xz",
+ "lzop",
+);
+
+
+/* lxcSaveImageGetCompressionProgram:
+ * @imageFormat: String representation from lxc.conf for the compression
+ * image format being used (dump, save, or snapshot).
+ * @compresspath: Pointer to a character string to store the fully qualified
+ * path from virFindFileInPath.
+ * @styleFormat: String representing the style of format (dump, save, snapshot)
+ *
+ * Returns:
+ * virQEMUSaveFormat - Integer representation of the compression
+ * program to be used for particular style
+ * (e.g. dump, save, or snapshot).
+ * LXC_SAVE_FORMAT_RAW - If there is no lxc.conf imageFormat value or
+ * no there was an error, then just return RAW
+ * indicating none.
+ */
+static int
+lxcSaveImageGetCompressionProgram(const char *imageFormat,
+ virCommandPtr *compressor,
+ const char *styleFormat)
+{
+ const char *prog;
+ int ret;
+
+ *compressor = NULL;
+
+ /* Use tar to compress all .img files */
+ if (!(prog = virFindFileInPath("tar")))
+ return -1;
+
+ *compressor = virCommandNew(prog);
+
+ if (STREQ(styleFormat, "save")) {
+ /* Remove files after added into tar */
+ virCommandAddArgList(*compressor, "--create",
+ "--remove-files", NULL);
+ } else if (STREQ(styleFormat, "dump")) {
+ virCommandAddArg(*compressor, "--extract");
+ } else {
+ return -1;
+ }
+
+ if (!imageFormat)
+ return 0;
+
+ if ((ret = lxcSaveCompressionTypeFromString(imageFormat)) < 0)
+ return -1;
+
+ switch (ret) {
+ case LXC_SAVE_FORMAT_GZIP:
+ virCommandAddArg(*compressor, "--gzip");
+ break;
+ case LXC_SAVE_FORMAT_BZIP2:
+ virCommandAddArg(*compressor, "--bzip2");
+ break;
+ case LXC_SAVE_FORMAT_XZ:
+ virCommandAddArg(*compressor, "--xz");
+ break;
+ case LXC_SAVE_FORMAT_LZOP:
+ virCommandAddArg(*compressor, "--lzop");
+ break;
+ case LXC_SAVE_FORMAT_RAW:
+ default:
+ break;
+ }
+
+ return ret;
+}
+
+
+int lxcCriuCompress(const char *checkpointdir,
+ char *compressionType)
+{
+ virCommandPtr cmd;
+ g_autofree char *tarfile = NULL;
+ int ret = -1;
+
+ if ((ret = lxcSaveImageGetCompressionProgram(compressionType,
+ &cmd,
+ "save")) < 0)
+ return -1;
+
+ tarfile = g_strdup_printf("%s/criu.save", checkpointdir);
+
+ virCommandAddArgFormat(cmd, "--file=%s", tarfile);
+ virCommandAddArgFormat(cmd, "--directory=%s/save/", checkpointdir);
+ virCommandAddArg(cmd, ".");
+
+ if (virCommandRun(cmd, NULL) < 0)
+ return -1;
+
+ return ret;
+}
+
+
+int lxcCriuDecompress(const char *checkpointdir,
+ char *compressionType)
+{
+ virCommandPtr cmd;
+ g_autofree char *tarfile = NULL;
+ g_autofree char *savedir = NULL;
+ int ret = -1;
+
+ if ((ret = lxcSaveImageGetCompressionProgram(compressionType,
+ &cmd,
+ "dump")) < 0)
+ return -1;
+
+ savedir = g_strdup_printf("%s/save/", checkpointdir);
+ if (virFileMakePath(savedir) < 0) {
+ virReportSystemError(errno,
+ _("Failed to mkdir %s"), savedir);
+ return -1;
+ }
+
+ tarfile = g_strdup_printf("%s/criu.save", checkpointdir);
+
+ virCommandAddArgFormat(cmd, "--file=%s", tarfile);
+ virCommandAddArgFormat(cmd, "--directory=%s", savedir);
+
+ if (virCommandRun(cmd, NULL) < 0)
+ return -1;
+
+ return ret;
+}
+
+
+int lxcCriuDump(virDomainObjPtr vm,
+ const char *checkpointdir)
+{
+ int ret = -1;
+ virLXCDomainObjPrivatePtr priv = vm->privateData;
+ virCommandPtr cmd;
+ struct stat sb;
+ g_autofree char *path = NULL;
+ g_autofree char *tty_info_path = NULL;
+ g_autofree char *ttyinfo = NULL;
+ g_autofree char *pidfile = NULL;
+ g_autofree char *pidbuf = NULL;
+ g_autofree char *savedir = NULL;
+ int pidlen;
+ int pidfd;
+ int status;
+
+ savedir = g_strdup_printf("%s/save/", checkpointdir);
+ if (virFileMakePath(savedir) < 0) {
+ virReportSystemError(errno,
+ _("Failed to mkdir %s"), savedir);
+ return -1;
+ }
+
+ pidfile = g_strdup_printf("%s/save/dump.pid", checkpointdir);
+ pidbuf = g_strdup_printf("%d", priv->initpid);
+ pidlen = strlen(pidbuf);
+
+ pidfd = open(pidfile, O_WRONLY | O_CREAT | O_TRUNC, 0644);
+ if (safewrite(pidfd, pidbuf, pidlen) != pidlen) {
+ virReportSystemError(errno, "%s", _("criu pid file write failed"));
+ return -1;
+ }
+
+ cmd = virCommandNew(CRIU);
+ virCommandAddArg(cmd, "dump");
+
+ virCommandAddArgList(cmd, "--images-dir", savedir, NULL);
+
+ virCommandAddArgList(cmd, "--log-file", "dump.log", NULL);
+
+ virCommandAddArgList(cmd, "-vvvv", NULL);
+
+ virCommandAddArg(cmd, "--tree");
+ virCommandAddArgFormat(cmd, "%d", priv->initpid);
+
+ virCommandAddArgList(cmd, "--tcp-established", "--file-locks",
+ "--link-remap", "--force-irmap", NULL);
+
+ virCommandAddArgList(cmd, "--manage-cgroup", NULL);
+
+ virCommandAddArgList(cmd, "--enable-external-sharing",
+ "--enable-external-masters", NULL);
+
+ virCommandAddArgList(cmd, "--enable-fs", "hugetlbfs",
+ "--enable-fs", "tracefs", NULL);
+
+ /* Add support for FUSE */
+ virCommandAddArgList(cmd, "--ext-mount-map", "/proc/meminfo:fuse", NULL);
+ virCommandAddArgList(cmd, "--ghost-limit", "10000000", NULL);
+
+ virCommandAddArgList(cmd, "--ext-mount-map", "/dev/console:console", NULL);
+ virCommandAddArgList(cmd, "--ext-mount-map", "/dev/tty1:tty1", NULL);
+ virCommandAddArgList(cmd, "--ext-mount-map", "auto", NULL);
+
+ /* The master pair of the /dev/pts device lives outside from what is dumped
+ * inside the libvirt-lxc process. Add the slave pair as an external tty
+ * otherwise criu will fail.
+ */
+ path = g_strdup_printf("/proc/%d/root/dev/pts/0", priv->initpid);
+
+ if (stat(path, &sb) < 0) {
+ virReportSystemError(errno,
+ _("Unable to stat %s"), path);
+ goto cleanup;
+ }
+
+ tty_info_path = g_strdup_printf("%s/tty.info", savedir);
+ ttyinfo = g_strdup_printf("tty[%x:%x]", (unsigned int)sb.st_rdev,
+ (unsigned int)sb.st_dev);
+
+ if (virFileWriteStr(tty_info_path, ttyinfo, 0666) < 0) {
+ virReportError(VIR_ERR_INTERNAL_ERROR,
+ _("Failed to write tty info to %s"), tty_info_path);
+ goto cleanup;
+ }
+
+ VIR_DEBUG("tty.info: tty[%x:%x]",
+ (unsigned int)sb.st_dev, (unsigned int)sb.st_rdev);
+ virCommandAddArg(cmd, "--external");
+ virCommandAddArgFormat(cmd, "tty[%x:%x]",
+ (unsigned int)sb.st_rdev, (unsigned int)sb.st_dev);
+
+ VIR_DEBUG("About to checkpoint domain %s (pid = %d)",
+ vm->def->name, priv->initpid);
+ virCommandRawStatus(cmd);
+ if (virCommandRun(cmd, &status) < 0)
+ goto cleanup;
+
+ ret = 0;
+
+ cleanup:
+ if (ret < 0)
+ return ret;
+ return status;
+}
+
+int lxcCriuRestore(virDomainDefPtr def,
+ int restorefd, int ttyfd)
+{
+ virCommandPtr cmd;
+ g_autofree char *ttyinfo = NULL;
+ g_autofree char *inheritfd = NULL;
+ g_autofree char *tty_info_path = NULL;
+ g_autofree char *checkpointfd = NULL;
+ g_autofree char *checkpointdir = NULL;
+ g_autofree char *rootfs_mount = NULL;
+ g_autofree gid_t *groups = NULL;
+ int ret = -1;
+ int ngroups;
+
+ cmd = virCommandNew(CRIU);
+ virCommandAddArg(cmd, "restore");
+
+ checkpointfd = g_strdup_printf("/proc/self/fd/%d", restorefd);
+
+ if (virFileResolveLink(checkpointfd, &checkpointdir) < 0) {
+ virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+ _("Failed to readlink checkpoint dir path"));
+ return -1;
+ }
+
+ /* CRIU needs the container's root bind mounted so that it is the root of
+ * some mount.
+ */
+ rootfs_mount = g_strdup_printf("%s/save/%s", LXC_STATE_DIR, def->name);
+
+ virCommandAddArgList(cmd, "--images-dir", checkpointdir, NULL);
+
+ virCommandAddArgList(cmd, "--log-file", "restore.log", NULL);
+
+ virCommandAddArgList(cmd, "--pidfile", "restore.pid", NULL);
+
+ virCommandAddArgList(cmd, "-vvvv", NULL);
+ virCommandAddArgList(cmd, "--tcp-established", "--file-locks",
+ "--link-remap", "--force-irmap", NULL);
+
+ virCommandAddArgList(cmd, "--enable-external-sharing",
+ "--enable-external-masters", NULL);
+
+ virCommandAddArgList(cmd, "--ext-mount-map", "auto", NULL);
+
+ virCommandAddArgList(cmd, "--enable-fs", "hugetlbfs",
+ "--enable-fs", "tracefs", NULL);
+
+ virCommandAddArgList(cmd, "--ext-mount-map", "fuse:/proc/meminfo", NULL);
+
+ virCommandAddArgList(cmd, "--ext-mount-map", "console:/dev/console", NULL);
+ virCommandAddArgList(cmd, "--ext-mount-map", "tty1:/dev/tty1", NULL);
+
+ virCommandAddArgList(cmd, "--restore-detached", "--restore-sibling", NULL);
+
+ /* Restore external tty that was saved in tty.info file
+ */
+ tty_info_path = g_strdup_printf("%s/tty.info", checkpointdir);
+
+ if (virFileReadAll(tty_info_path, 1024, &ttyinfo) < 0) {
+ virReportError(VIR_ERR_INTERNAL_ERROR,
+ _("Failed to read tty info from %s"), tty_info_path);
+ return -1;
+ }
+
+ inheritfd = g_strdup_printf("fd[%d]:%s", ttyfd, ttyinfo);
+
+ virCommandAddArgList(cmd, "--inherit-fd", inheritfd, NULL);
+
+ /* Change the root filesystem because we run in mount namespace.
+ */
+ virCommandAddArgList(cmd, "--root", rootfs_mount, NULL);
+
+ if ((ngroups = virGetGroupList(virCommandGetUID(cmd), virCommandGetGID(cmd),
+ &groups)) < 0)
+ return -1;
+
+
+ VIR_DEBUG("Executing init binary");
+ /* this function will only return if an error occurred */
+ ret = virCommandExec(cmd, groups, ngroups);
+
+ if (ret != 0) {
+ VIR_DEBUG("Tearing down container");
+ fprintf(stderr,
+ _("Failure in libvirt_lxc startup: %s\n"),
+ virGetLastErrorMessage());
+ }
+
+ return ret;
+}
+#else
+int lxcCriuDump(virDomainObjPtr vm ATTRIBUTE_UNUSED,
+ const char *checkpointdir ATTRIBUTE_UNUSED)
+{
+ virReportUnsupportedError();
+ return -1;
+}
+
+int lxcCriuRestore(virDomainDefPtr def ATTRIBUTE_UNUSED,
+ int fd ATTRIBUTE_UNUSED,
+ int ttyfd ATTRIBUTE_UNUSED)
+{
+ virReportUnsupportedError();
+ return -1;
+}
+#endif
diff --git a/src/lxc/lxc_criu.h b/src/lxc/lxc_criu.h
new file mode 100644
index 0000000000..7dfd78aa24
--- /dev/null
+++ b/src/lxc/lxc_criu.h
@@ -0,0 +1,50 @@
+/*
+ * lxc_criu.h: CRIU C API methods wrapper
+ *
+ * Copyright (c) 2021 Red Hat, Inc.
+ *
+ * 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, see
+ * <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef LXC_CRIU_H
+# define LXC_CRIU_H
+
+# include "virobject.h"
+
+#define LXC_SAVE_MAGIC "LXCCriuSaveMagic"
+#define LXC_SAVE_VERSION 2
+
+typedef struct _virLXCSaveHeader virLXCSaveHeader;
+typedef virLXCSaveHeader *virLXCSaveHeaderPtr;
+struct _virLXCSaveHeader {
+ char magic[sizeof(LXC_SAVE_MAGIC)-1];
+ uint32_t version;
+ uint32_t xmlLen;
+ uint32_t compressed;
+ uint32_t unused[9];
+};
+
+int lxcCriuCompress(const char *checkpointdir,
+ char *compressionType);
+
+int lxcCriuDecompress(const char *checkpointdir,
+ char *compressionType);
+
+int lxcCriuDump(virDomainObjPtr vm,
+ const char *checkpointdir);
+
+int lxcCriuRestore(virDomainDefPtr def,
+ int fd, int ttyfd);
+#endif /* LXC_CRIU_H */
diff --git a/src/lxc/meson.build b/src/lxc/meson.build
index ad5c659dba..1a8524aab3 100644
--- a/src/lxc/meson.build
+++ b/src/lxc/meson.build
@@ -9,6 +9,7 @@ lxc_driver_sources = [
'lxc_monitor.c',
'lxc_native.c',
'lxc_process.c',
+ 'lxc_criu.c',
]
lxc_monitor_protocol = files('lxc_monitor_protocol.x')
@@ -61,6 +62,7 @@ lxc_controller_sources = files(
'lxc_domain.c',
'lxc_fuse.c',
'lxc_controller.c',
+ 'lxc_criu.c',
)
lxc_controller_generated = custom_target(
--
2.27.0
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