[CRIU] [PATCH v8 05/15] autofs: dump fsinfo stage introduced
Stanislav Kinsburskiy
skinsbursky at virtuozzo.com
Wed Mar 16 06:17:20 PDT 2016
AutoFS mount point is managed by user space daemon, which receives
requests from kernel via pipe, passed on mount operation.
Kernel hold write end, while user space process - read end.
Thus, for successful AutoFS migration, this connection has to be
restored.
During this stage, all the autofs parameters and parsed and collected in
per-mount autofs structure. It also does check that autofs mounts is not in
interim state.
Below are major tricks to be performed to dump AutoFS mount:
1) Read end of the pipe in the process have to be discovered: it will be used
to restore the pipe in case of write pipe end in closed in the process.
Note: migration of AutoFS mounts, which process group leader doesn't have read
pipe end opened is not supported.
2) Read pipe end has to be empty. Otherwise autofs is an interim state.
Interim state is determined by control pipe contents: if it's not empty, then
it means, that kernel requested some operation (mount/umount), which is in
process right now.
In case of pipe is not empty, dump is aborted.
3) Mount points are collected (parsed) from initial pid namespace, which leads
to real pgrp value in AutoFS options instead of virtual one. This have to be
fixed.
Note: we don't care about virtual pgrp in case of catatonic mounts
Signed-off-by: Stanislav Kinsburskiy <skinsbursky at virtuozzo.com>
---
criu/autofs.c | 285 +++++++++++++++++++++++++++++++++++++++++++++++++
criu/include/autofs.h | 1
criu/mount.c | 2
3 files changed, 287 insertions(+), 1 deletion(-)
diff --git a/criu/autofs.c b/criu/autofs.c
index ca7c21b..ca5c853 100644
--- a/criu/autofs.c
+++ b/criu/autofs.c
@@ -1,10 +1,24 @@
+#include <unistd.h>
+#include <sys/stat.h>
+
#include "proc_parse.h"
#include "autofs.h"
#include "util.h"
#include "mount.h"
+#include "pstree.h"
+#include "namespaces.h"
+#include "protobuf.h"
+
+#include "images/autofs.pb-c.h"
#define AUTOFS_OPT_UNKNOWN INT_MIN
+#define AUTOFS_MODE_DIRECT 0
+#define AUTOFS_MODE_INDIRECT 1
+#define AUTOFS_MODE_OFFSET 2
+
+#define AUTOFS_CATATONIC_FD -1
+
struct autofs_pipe_s {
struct list_head list;
unsigned long inode;
@@ -59,3 +73,274 @@ int autofs_parse(struct mount_info *pm)
return autofs_gather_pipe(pipe_ino);
}
+
+static int autofs_check_fd_stat(struct stat *stat, int prgp, int fd,
+ long ino, int *mode)
+{
+ struct fdinfo_common fdinfo;
+
+ if (!S_ISFIFO(stat->st_mode))
+ return 0;
+ if (stat->st_ino != ino)
+ return 0;
+ if (parse_fdinfo_pid(prgp, fd, FD_TYPES__UND, NULL, &fdinfo))
+ return -1;
+
+ *mode = fdinfo.flags & O_WRONLY;
+ return 1;
+}
+
+static int autofs_kernel_pipe_alive(int pgrp, int fd, int ino)
+{
+ struct stat buf;
+ char *path;
+ int ret, fd_mode;
+
+ path = xsprintf("/proc/%d/fd/%d", pgrp, fd);
+ if (!path)
+ return -1;
+
+ if (stat(path, &buf) < 0) {
+ if (errno == ENOENT)
+ return 0;
+ pr_perror("Failed to stat %s", path);
+ return -1;
+ }
+
+ xfree(path);
+
+ ret = autofs_check_fd_stat(&buf, pgrp, fd, ino, &fd_mode);
+ if (ret <= 0)
+ return ret;
+
+ return O_WRONLY == fd_mode;
+}
+
+static int autofs_find_pipe_read_end(int pgrp, long ino, int *read_fd)
+{
+ DIR *dir;
+ struct dirent *de;
+ int ret = -1;
+
+ dir = opendir_proc(pgrp, "fd");
+ if (dir == NULL)
+ return -1;
+
+ *read_fd = -1;
+
+ while ((de = readdir(dir))) {
+ struct stat buf;
+ int found, mode, fd;
+
+ if (dir_dots(de))
+ continue;
+
+ if (fstatat(dirfd(dir), de->d_name, &buf, 0) < 0) {
+ pr_perror("Failed to fstatat");
+ break;
+ }
+
+ fd = atoi(de->d_name);
+
+ found = autofs_check_fd_stat(&buf, pgrp, fd, ino, &mode);
+ if (found < 0)
+ break;
+ if (found && (mode == O_RDONLY)) {
+ *read_fd = fd;
+ ret = 0;
+ break;
+ }
+ }
+
+ closedir(dir);
+ close_pid_proc();
+
+ return ret;
+}
+
+static int autofs_find_read_fd(int pgrp, long pipe_ino)
+{
+ int read_fd, fd;
+
+ /* We need to find read end and make sure, that it's empty */
+ if (autofs_find_pipe_read_end(pgrp, pipe_ino, &read_fd) < 0) {
+ pr_err("Failed to find read pipe fd (ino %ld) "
+ "in process %d\n", pipe_ino, pgrp);
+ return -1;
+ }
+
+ if (read_fd == -1) {
+ pr_err("Master %d doesn't have a read end of the pipe with "
+ "inode %ld opened\n", pgrp, pipe_ino);
+ pr_err("Abandoned mount or control was delegated to child?\n");
+ return -1;
+ }
+
+ /* Let's check, that read end is empty */
+ fd = open_proc(pgrp, "fd/%d", read_fd);
+ if (fd < 0)
+ return -1;
+
+ if (fd_has_data(fd)) {
+ pr_err("Process %d autofs pipe fd %d is not empty.\n", pgrp,
+ read_fd);
+ pr_err("Try again later.\n");
+ return -1;
+ }
+ close(fd);
+ return read_fd;
+}
+
+static int parse_options(char *options, AutofsEntry *entry, long *pipe_ino)
+{
+ char **opts;
+ int nr_opts, i;
+
+ entry->fd = AUTOFS_OPT_UNKNOWN;
+ entry->timeout = AUTOFS_OPT_UNKNOWN;
+ entry->minproto = AUTOFS_OPT_UNKNOWN;
+ entry->maxproto = AUTOFS_OPT_UNKNOWN;
+ entry->mode = AUTOFS_OPT_UNKNOWN;
+ entry->pgrp = AUTOFS_OPT_UNKNOWN;
+ entry->uid = AUTOFS_OPT_UNKNOWN;
+ entry->gid = AUTOFS_OPT_UNKNOWN;
+ *pipe_ino = AUTOFS_OPT_UNKNOWN;
+
+ split(options, ',', &opts, &nr_opts);
+ if (!opts)
+ return -1;
+
+ for (i = 0; i < nr_opts; i++) {
+ char *opt = opts[i];
+
+ if (!strncmp(opt, "fd=", strlen("fd=")))
+ entry->fd = atoi(opt + strlen("fd="));
+ else if (!strncmp(opt, "pipe_ino=", strlen("pipe_ino=")))
+ *pipe_ino = atoi(opt + strlen("pipe_ino="));
+ else if (!strncmp(opt, "pgrp=", strlen("pgrp=")))
+ entry->pgrp = atoi(opt + strlen("pgrp="));
+ else if (!strncmp(opt, "timeout=", strlen("timeout=")))
+ entry->timeout = atoi(opt + strlen("timeout="));
+ else if (!strncmp(opt, "minproto=", strlen("minproto=")))
+ entry->minproto = atoi(opt + strlen("minproto="));
+ else if (!strncmp(opt, "maxproto=", strlen("maxproto=")))
+ entry->maxproto = atoi(opt + strlen("maxproto="));
+ else if (!strcmp(opt, "indirect"))
+ entry->mode = AUTOFS_MODE_INDIRECT;
+ else if (!strcmp(opt, "offset"))
+ entry->mode = AUTOFS_MODE_OFFSET;
+ else if (!strcmp(opt, "direct"))
+ entry->mode = AUTOFS_MODE_DIRECT;
+ else if (!strncmp(opt, "uid=", strlen("uid=")))
+ entry->uid = atoi(opt + strlen("uid="));
+ else if (!strncmp(opt, "gid=", strlen("gid=")))
+ entry->gid = atoi(opt + strlen("gid="));
+ }
+
+ for (i = 0; i < nr_opts; i++)
+ xfree(opts[i]);
+ xfree(opts);
+
+ if (entry->fd == AUTOFS_OPT_UNKNOWN) {
+ pr_err("Failed to find fd option\n");
+ return -1;
+ }
+ if (entry->pgrp == AUTOFS_OPT_UNKNOWN) {
+ pr_err("Failed to find pgrp option\n");
+ return -1;
+ }
+ if (entry->timeout == AUTOFS_OPT_UNKNOWN) {
+ pr_err("Failed to find timeout option\n");
+ return -1;
+ }
+ if (entry->minproto == AUTOFS_OPT_UNKNOWN) {
+ pr_err("Failed to find minproto option\n");
+ return -1;
+ }
+ if (entry->maxproto == AUTOFS_OPT_UNKNOWN) {
+ pr_err("Failed to find maxproto option\n");
+ return -1;
+ }
+ if (entry->mode == AUTOFS_OPT_UNKNOWN) {
+ pr_err("Failed to find mode (direct,indirect,offset) option\n");
+ return -1;
+ }
+ if (*pipe_ino == AUTOFS_OPT_UNKNOWN) {
+ pr_err("Failed to find pipe_ino option (old kernel?)\n");
+ return -1;
+ }
+
+ return 0;
+}
+
+static int autofs_create_entry(struct mount_info *pm, AutofsEntry *entry)
+{
+ long pipe_ino;
+
+ if (parse_options(pm->options, entry, &pipe_ino))
+ return -1;
+
+ if (entry->uid != AUTOFS_OPT_UNKNOWN)
+ entry->has_uid = true;
+ if (entry->gid != AUTOFS_OPT_UNKNOWN)
+ entry->has_gid = true;
+
+ if (entry->fd != AUTOFS_CATATONIC_FD) {
+ int found, read_fd;
+
+ read_fd = autofs_find_read_fd(entry->pgrp, pipe_ino);
+ if (read_fd < 0)
+ return -1;
+
+ /* Let' check whether write end is still open */
+ found = autofs_kernel_pipe_alive(entry->pgrp, entry->fd, pipe_ino);
+ if (found < 0) {
+ pr_err("Failed to check fd %d in process %d\n",
+ entry->fd, entry->pgrp);
+ return -1;
+ }
+ /* Write end is absent. we need to carry read end to restore. */
+ if (!found) {
+ entry->has_read_fd = true;
+ entry->read_fd = read_fd;
+ }
+
+ /* We need to get virtual pgrp to restore mount */
+ entry->pgrp = pid_to_virt(entry->pgrp);
+ if (!entry->pgrp) {
+ pr_err("failed to find pstree item with pid %d\n",
+ entry->pgrp);
+ pr_err("Non-catatonic mount without master?\n");
+ return -1;
+ }
+ }
+ return 0;
+}
+
+static int autofs_dump_entry(struct mount_info *pm, AutofsEntry *entry)
+{
+ struct cr_img *img;
+ int ret = -1;
+
+ img = open_image(CR_FD_AUTOFS, O_DUMP, pm->s_dev);
+ if (img)
+ ret = pb_write_one(img, entry, PB_AUTOFS);
+ close_image(img);
+ return ret;
+}
+
+
+int autofs_dump(struct mount_info *pm)
+{
+ AutofsEntry *entry;
+
+ entry = xmalloc(sizeof(*entry));
+ if (!entry)
+ return -1;
+ autofs_entry__init(entry);
+
+ if (autofs_create_entry(pm, entry))
+ return -1;
+
+ return autofs_dump_entry(pm, entry);
+}
diff --git a/criu/include/autofs.h b/criu/include/autofs.h
index c0dbe8d..66e4338 100644
--- a/criu/include/autofs.h
+++ b/criu/include/autofs.h
@@ -9,5 +9,6 @@ bool is_autofs_pipe(unsigned long inode);
struct mount_info;
int autofs_parse(struct mount_info *pm);
+int autofs_dump(struct mount_info *pm);
#endif
diff --git a/criu/mount.c b/criu/mount.c
index 2958365..ea5aae7 100644
--- a/criu/mount.c
+++ b/criu/mount.c
@@ -1699,7 +1699,7 @@ static struct fstype fstypes[32] = {
.name = "autofs",
.code = FSTYPE__AUTOFS,
.parse = autofs_parse,
- .dump = always_fail,
+ .dump = autofs_dump,
.restore = always_fail,
},
};
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