[CRIU] [PATCH v2 05/17] spfs: delayed mounts facility introduced
Stanislav Kinsburskiy
skinsbursky at virtuozzo.com
Thu May 19 02:23:20 PDT 2016
This facility allows to migated such mounts, like NFS, by replacing the actual
mount by FUSE (spfs) mount.
Spfs allows to create and open files, required for restore, and then (by
switching spfs to "Stub" mode) to block any incomming file system requests.
This facility does spfs mount via spfs manager, which is then instructed, how
to mount the actual file system.
Spfs manager is also responsible for replacing of spfs mount and opened files
by the actual one (and actual files) once actual mount point is remounted.
Signed-off-by: Stanislav Kinsburskiy <skinsbursky at virtuozzo.com>
---
criu/Makefile.crtools | 1
criu/include/spfs.h | 13 +
criu/spfs.c | 447 +++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 461 insertions(+)
create mode 100644 criu/include/spfs.h
create mode 100644 criu/spfs.c
diff --git a/criu/Makefile.crtools b/criu/Makefile.crtools
index 657b08e..3d246f1 100644
--- a/criu/Makefile.crtools
+++ b/criu/Makefile.crtools
@@ -78,6 +78,7 @@ obj-y += util.o
obj-y += uts_ns.o
obj-y += autofs.o
obj-y += uffd.o
+obj-y += spfs.o
ifeq ($(VDSO),y)
obj-y += pie-util-vdso.o
diff --git a/criu/include/spfs.h b/criu/include/spfs.h
new file mode 100644
index 0000000..395572c
--- /dev/null
+++ b/criu/include/spfs.h
@@ -0,0 +1,13 @@
+#ifndef __CR_SPFS_H__
+#define __CR_SPFS_H__
+
+int spfs_set_env(void);
+
+struct mount_info;
+int spfs_mount(struct mount_info *mi, const char *source,
+ const char *filesystemtype, unsigned long mountflags);
+
+struct reg_file_info;
+int spfs_create_file(int ns_root_id, const struct reg_file_info *rfi);
+
+#endif
diff --git a/criu/spfs.c b/criu/spfs.c
new file mode 100644
index 0000000..68ea1c9
--- /dev/null
+++ b/criu/spfs.c
@@ -0,0 +1,447 @@
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+
+#include <unistd.h>
+#include <libgen.h>
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <sys/stat.h>
+
+#include "mount.h"
+#include "log.h"
+#include "util.h"
+#include "cr_options.h"
+#include "namespaces.h"
+#include "files-reg.h"
+#include "pstree.h"
+#include "spfs.h"
+
+#define SPFS_MANAGER_WORK_DIR "/run/spfs-manager/%d"
+#define SPFS_MANAGER_SOCK_FILE "control.sock"
+
+static int sock_seqpacket_connect(char *path)
+{
+ int sock, err;
+ struct sockaddr_un addr;
+
+ sock = socket(AF_UNIX, SOCK_SEQPACKET, 0);
+ if (sock < 0) {
+ pr_perror("Failed to create packet socket");
+ return -1;
+ }
+ memset(&addr, 0, sizeof(struct sockaddr_un));
+
+ addr.sun_family = AF_UNIX;
+ strncpy(addr.sun_path, path, sizeof(addr.sun_path) - 1);
+
+ err = connect(sock, (struct sockaddr *)&addr, sizeof(addr));
+ if (err) {
+ pr_perror("failed to connect to socket %s (-%d)", addr.sun_path, errno);
+ return -1;
+ }
+ return sock;
+}
+
+static int spfs_send_request(int sock, void *req, size_t len)
+{
+ ssize_t bytes;
+ int status;
+
+ bytes = send(sock, req, len, MSG_EOR);
+ if (bytes < 0) {
+ pr_perror("failed to send request");
+ return -1;
+ }
+
+ bytes = recv(sock, &status, sizeof(status), 0);
+ if (bytes < 0) {
+ pr_perror("failed to receive reply via sock %d", sock);
+ return -1;
+ }
+ if (bytes == 0) {
+ pr_debug("%s: peer was closed\n", __func__);
+ return -ECONNABORTED;
+ }
+
+ return status;
+}
+
+
+static int create_dir(int ns_root_fd, const char *new_dir, mode_t mode)
+{
+ int pd = ns_root_fd, nd, err = -1;
+ char *path, *dentry;
+
+ path = strdup(new_dir);
+ if (path < 0) {
+ pr_err("failed to duplicate string\n");
+ return -ENOMEM;
+ }
+
+ while ((dentry = strsep(&path, "/")) != NULL) {
+ pr_debug("creating subdir: %s\n", dentry);
+ if (mkdirat(pd, dentry, 0777) && (errno != EEXIST)) {
+ pr_perror("failed to mkdir '%s'", dentry);
+ err = -errno;
+ goto close_pd;
+ }
+
+ nd = openat(pd, dentry, O_DIRECTORY | O_RDONLY, 0777);
+ if (nd < 0) {
+ pr_perror("failed to open subdirectory %s", dentry);
+ err = -errno;
+ goto close_pd;
+ }
+ if (pd != ns_root_fd)
+ close(pd);
+ pd = nd;
+ }
+
+ err = 0;
+
+close_pd:
+ if (pd != ns_root_fd)
+ close(pd);
+ free(path);
+ return err;
+}
+
+static int create_reg_file(int ns_root_fd, const char *file_path, mode_t mode, size_t size)
+{
+ char *path;
+ int fd, err;
+
+ path = strdup(file_path);
+ if (path < 0) {
+ pr_err("failed to duplicate string\n");
+ return -ENOMEM;
+ }
+
+ err = create_dir(ns_root_fd, dirname(path), 077);
+ if (err < 0)
+ goto free_path;
+
+ fd = openat(ns_root_fd, file_path, O_CREAT | O_EXCL | O_WRONLY, 0777);
+ if ((fd < 0) && (errno != EEXIST)) {
+ pr_perror("failed to create regular file %s", file_path);
+ err = -errno;
+ goto free_path;
+ }
+
+ if (faccessat(ns_root_fd, file_path, W_OK | R_OK | X_OK, 0)) {
+ pr_perror("file %s is not accessible", file_path);
+ err = -errno;
+ goto close_fd;
+ }
+
+ if (size && ftruncate(fd, size)) {
+ pr_perror("failed to truncate %s to %ld bytes", file_path, size);
+ err = -errno;
+ goto close_fd;
+ }
+
+ pr_debug("file %s was created with mode 0777 and size %ld\n", file_path, size);
+
+close_fd:
+ close(fd);
+free_path:
+ free(path);
+ return err;
+}
+
+static int create_fifo(int ns_root_fd, const char *file_path, mode_t mode, size_t size)
+{
+ char *path;
+ int err;
+
+ path = strdup(file_path);
+ if (path < 0) {
+ pr_err("failed to duplicate string\n");
+ return -ENOMEM;
+ }
+
+ err = create_dir(ns_root_fd, dirname(path), 0777);
+ if (err)
+ goto free_path;
+
+ if (mkfifoat(ns_root_fd, file_path, 0777) && (errno != EEXIST)) {
+ pr_perror("failed to create fifo %s", file_path);
+ err = -errno;
+ goto free_path;
+ }
+
+ if (faccessat(ns_root_fd, file_path, W_OK | R_OK | X_OK, 0)) {
+ pr_perror("fifo %s is not accessible", file_path);
+ err = -errno;
+ goto free_path;
+ }
+
+ if (size) {
+ pr_err("fifo with size?\n");
+ err = -ENOTSUP;
+ goto free_path;
+ }
+
+ pr_debug("fifo %s was created with mode 0777 and size %ld\n", file_path, size);
+
+free_path:
+ free(path);
+ return err;
+}
+
+int spfs_create_file(int ns_root_fd, const struct reg_file_info *rfi)
+{
+ const char *path = rfi->path;
+ int mode;
+ int err;
+ size_t size = 0;
+
+ pr_debug("%s: full path: %s\n", __func__, path);
+
+ if (!rfi->rfe->has_mode) {
+ pr_err("Image doesn't have mode value\n");
+ return -1;
+ }
+ mode = rfi->rfe->mode;
+
+ if (!faccessat(ns_root_fd, path, F_OK, AT_SYMLINK_NOFOLLOW)) {
+ pr_info("path %s already exists\n", path);
+ return 0;
+ }
+
+ if (rfi->rfe->has_size)
+ size = rfi->rfe->size;
+
+ switch (mode & S_IFMT) {
+ case S_IFDIR:
+ err = create_dir(ns_root_fd, path, 0777);
+ break;
+ case S_IFREG:
+ err = create_reg_file(ns_root_fd, path, 0777, size);
+ break;
+ case S_IFSOCK:
+ pr_err("sockets not supported yet\n");
+ return -EINVAL;
+ case S_IFLNK:
+ pr_err("links not supported yet\n");
+ return -EINVAL;
+ case S_IFBLK:
+ pr_err("block devices not supported yet\n");
+ return -EINVAL;
+ case S_IFCHR:
+ pr_err("character devices not supported yet\n");
+ return -EINVAL;
+ case S_IFIFO:
+ err = create_fifo(ns_root_fd, path, 0777, size);
+ break;
+ default:
+ pr_err("unknown mode: %d\n", mode);
+ return -EINVAL;
+ }
+ return err;
+}
+
+static char *spfs_manager_work_dir(void)
+{
+ static char work_dir[PATH_MAX] = { };
+
+ if (strlen(work_dir) == 0) {
+ snprintf(work_dir, PATH_MAX, SPFS_MANAGER_WORK_DIR,
+ root_item->pid.real);
+ }
+ return work_dir;
+}
+
+char *spfs_manager_socket_path(void)
+{
+ static char socket_path[PATH_MAX] = { };
+
+ if (strlen(socket_path) == 0) {
+ snprintf(socket_path, PATH_MAX, "%s/%s",
+ spfs_manager_work_dir(), SPFS_MANAGER_SOCK_FILE);
+ }
+ return socket_path;
+}
+
+static int start_spfs_manager(void)
+{
+ char *spfs_manager = "spfs-manager";
+ char *socket_path = spfs_manager_socket_path();
+ int err = -ENOMEM, sock;
+
+ err = cr_system(-1, -1, -1, spfs_manager,
+ (char *[]){ "spfs-manager", "-vvvv",
+ "-d",
+ "--socket-path", socket_path,
+ "--work-dir", spfs_manager_work_dir(),
+ "--exit-with-spfs", NULL },
+ 0);
+ pr_info("%s: spfs manager start result: %d\n", __func__, err);
+ if (err)
+ return err;
+
+ sock = sock_seqpacket_connect(socket_path);
+ if (sock < 0)
+ return sock;
+
+ err = install_service_fd(SPFS_MNGR_SK, sock);
+ if (err < 0) {
+ close(sock);
+ pr_err("failed to install SPFS manager service socket\n");
+ return err;
+ }
+
+ return sock;
+}
+
+static int get_spfs_mngr_sock(void *arg, int fd, pid_t pid)
+{
+ int sock;
+
+ sock = get_service_fd(SPFS_MNGR_SK);
+ if (sock < 0)
+ sock = start_spfs_manager();
+ return sock;
+}
+
+static int spfs_request_mount(int sock, struct mount_info *mi, const char *source,
+ const char *type, unsigned long mountflags)
+{
+ int err = -ENOMEM;
+ char *mountpoint, *freeze_cgroup, *mount, *replace, *bindmounts = NULL;
+ struct mount_info *bm;
+ int len;
+
+ list_for_each_entry(bm, &mi->mnt_bind, mnt_bind) {
+ bindmounts = xstrcat(bindmounts, "%s,", bm->ns_mountpoint);
+ if (!bindmounts) {
+ pr_err("failed to construct bindmounts parameter\n");
+ return -ENOMEM;
+ }
+ }
+ /* Trim last comma */
+ bindmounts[strlen(bindmounts)] = '\0';
+
+ mountpoint = xsprintf("%s", mi->ns_mountpoint);
+ if (!mountpoint) {
+ pr_err("failed to allocate\n");
+ goto free_bindmounts;
+ }
+
+ freeze_cgroup = xsprintf("/sys/fs/cgroup/freezer/%s", opts.new_global_cg_root);
+ if (!freeze_cgroup) {
+ pr_err("failed to construct freeze_cgroup\n");
+ goto free_mountpoint;
+ }
+
+ mount = xsprintf("mount;id=%d;mode=restore;mountpoint=%s;"
+ "ns_pid=%d;ns_list=user,net,mnt;root=%s", mi->mnt_id,
+ mountpoint, root_item->pid.real, opts.root);
+ if (!mount) {
+ pr_err("failed to allocate mount request\n");
+ goto free_freeze_cgroup;
+ }
+
+ replace = xsprintf("replace;id=%d;source=%s;type=%s;flags=%ld;bindmounts=%s;freeze_cgroup=%s;",
+ mi->mnt_id, source, type, mountflags, bindmounts, freeze_cgroup);
+ if (!replace) {
+ pr_err("failed to allocate replace request\n");
+ goto free_mount;
+ }
+ len = strlen(replace);
+
+ replace = xstrcat(replace, "%s", mi->options);
+ if (!replace) {
+ pr_err("failed to add options to replace request\n");
+ goto free_replace;
+ }
+ replace[len-1] = '\0';
+
+ pr_debug("Sending mount request: %s\n", mount);
+
+ err = spfs_send_request(sock, mount, strlen(mount) + 1);
+ if (err) {
+ pr_err("mount request failed: %d\n", err);
+ goto free_replace;
+ }
+
+ pr_debug("Mount request succeeded\n");
+
+ pr_debug("Sending replace request: %s\n", replace);
+ err = spfs_send_request(sock, replace, strlen(replace) + 1 +
+ strlen(mi->options) + 1);
+ if (err)
+ pr_err("replace request failed: %d\n", err);
+ else
+ pr_debug("Replace request succeeded\n");
+
+
+free_replace:
+ free(replace);
+free_mount:
+ free(mount);
+free_freeze_cgroup:
+ free(freeze_cgroup);
+free_mountpoint:
+ free(mountpoint);
+free_bindmounts:
+ free(bindmounts);
+ return err;
+
+}
+
+int spfs_mount(struct mount_info *mi, const char *source,
+ const char *filesystemtype, unsigned long mountflags)
+{
+ int ret;
+ int ns_fd;
+ int sock;
+
+ ns_fd = open_proc(PROC_SELF, "ns");
+ if (ns_fd < 0)
+ return ns_fd;
+
+ sock = userns_call(get_spfs_mngr_sock, UNS_FDOUT, NULL, 0, ns_fd);
+ close(ns_fd);
+ if (sock < 0) {
+ pr_err("failed to mount NFS to path %s\n", mi->mountpoint);
+ return sock;
+ }
+
+ ret = spfs_request_mount(sock, mi, source, filesystemtype, mountflags);
+ close(sock);
+ if (ret) {
+ pr_err("mount of %s (%s) failed: %d\n", source, filesystemtype, ret);
+ return ret;
+ }
+
+ return 0;
+}
+
+int spfs_set_env(void)
+{
+ char *mode, *socket_path;
+
+ if ((root_item == NULL) || (root_item->pid.real == -1))
+ return 0;
+
+ mode = "stub";
+ socket_path = spfs_manager_socket_path();
+
+ if (setenv("SPFS_MODE", mode, 1)) {
+ pr_perror("Can't set SPFS_MODE=%s", mode);
+ return -1;
+
+ }
+
+ if (setenv("SPFS_MANAGER_SOCK", socket_path, 1)) {
+ pr_perror("Can't set SPFS_MANAGER_SOCK=%s", socket_path);
+ return -1;
+
+ }
+
+ return 0;
+}
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