From 1328e32ee05c59f7168039211c9d96176ff22791 Mon Sep 17 00:00:00 2001
From: Jingxian He <hejingxian@huawei.com>
Date: Sat, 14 Aug 2021 16:45:40 +0800
Subject: [PATCH 45/72] add reuse file method for recover deleted file state

Orphan inode maybe exist in checkpoint process. Sometimes it can't be
re-linked by `linkat()` syscall, e.g. sysfs.

Therefore, add reuse file method for recover file state of deleted
files.

Signed-off-by: Jingxian He <hejingxian@huawei.com>
Signed-off-by: fu.lin <fulin10@huawei.com>
---
 criu/Makefile.crtools       |  1 +
 criu/files-reg.c            | 10 ++++--
 criu/files.c                | 22 +++++++++++-
 criu/include/orphan-inode.h | 16 +++++++++
 criu/orphan-inode.c         | 71 +++++++++++++++++++++++++++++++++++++
 5 files changed, 116 insertions(+), 4 deletions(-)
 create mode 100644 criu/include/orphan-inode.h
 create mode 100644 criu/orphan-inode.c

diff --git a/criu/Makefile.crtools b/criu/Makefile.crtools
index 3e522b4..7fee749 100644
--- a/criu/Makefile.crtools
+++ b/criu/Makefile.crtools
@@ -95,6 +95,7 @@ obj-y			+= devname.o
 obj-y			+= files-chr.o
 obj-y			+= exit-notify.o
 obj-y			+= reserved-ports.o
+obj-y			+= orphan-inode.o
 obj-$(CONFIG_HAS_LIBBPF)	+= bpfmap.o
 obj-$(CONFIG_COMPAT)	+= pie-util-vdso-elf32.o
 CFLAGS_pie-util-vdso-elf32.o	+= -DCONFIG_VDSO_32
diff --git a/criu/files-reg.c b/criu/files-reg.c
index 6dc8745..ed46764 100644
--- a/criu/files-reg.c
+++ b/criu/files-reg.c
@@ -46,6 +46,7 @@
 #include "external.h"
 #include "memfd.h"
 #include "files-chr.h"
+#include "orphan-inode.h"
 
 #include "protobuf.h"
 #include "util.h"
@@ -1260,8 +1261,10 @@ static int check_path_remap(struct fd_link *link, const struct fd_parms *parms,
 		 */
 
 		if (errno == ENOENT) {
-			link_strip_deleted(link);
-			return dump_linked_remap(rpath + 1, plen - 1, ost, lfd, id, nsid);
+			pr_info("Start add no exist file: %s\n", rpath+1);
+			add_reuse_file(id, lfd, dst_pid);
+			need_reuse_flag = O_REUSE;
+			return 0;
 		}
 
 		pr_perror("Can't stat path");
@@ -1663,7 +1666,8 @@ ext:
 	rfe.has_mode = true;
 	rfe.mode = p->stat.st_mode;
 
-	if (S_ISREG(p->stat.st_mode) && should_check_size(rfe.flags) && !store_validation_data(&rfe, p, lfd))
+	if (S_ISREG(p->stat.st_mode) && should_check_size(rfe.flags)
+	    && (need_reuse_flag != O_REUSE) && !store_validation_data(&rfe, p, lfd))
 		return -1;
 
 	fe.type = FD_TYPES__REG;
diff --git a/criu/files.c b/criu/files.c
index 1c52cf4..e79052e 100644
--- a/criu/files.c
+++ b/criu/files.c
@@ -50,6 +50,7 @@
 #include "fdstore.h"
 #include "bpfmap.h"
 #include "files-chr.h"
+#include "orphan-inode.h"
 
 #include "protobuf.h"
 #include "util.h"
@@ -706,6 +707,7 @@ int dump_my_file(int lfd, u32 *id, int *type)
 }
 
 int dst_pid;
+int need_reuse_flag;
 
 int dump_task_files_seized(struct parasite_ctl *ctl, struct pstree_item *item, struct parasite_drain_fd *dfds)
 {
@@ -743,10 +745,13 @@ int dump_task_files_seized(struct parasite_ctl *ctl, struct pstree_item *item, s
 		for (i = 0; i < nr_fds; i++) {
 			FdinfoEntry e = FDINFO_ENTRY__INIT;
 
+			need_reuse_flag = 0;
 			ret = dump_one_file(item->pid, dfds->fds[i + off], lfds[i], opts + i, ctl, &e, dfds);
 			if (ret)
 				break;
 
+			e.flags |= need_reuse_flag;
+			pr_info("write fdinfoEntry fd=%d id=%d\n", (&e)->fd, (&e)->id);
 			ret = pb_write_one(img, &e, PB_FDINFO);
 			if (ret)
 				break;
@@ -939,7 +944,8 @@ int collect_fd(int pid, FdinfoEntry *e, struct rst_info *rst_info, bool fake)
 {
 	struct file_desc *fdesc;
 
-	pr_info("Collect fdinfo pid=%d fd=%d id=%#x\n", pid, e->fd, e->id);
+	pr_info("Collect fdinfo pid=%d fd=%d id=%#x flags: %#x\n",
+		pid, e->fd, e->id, e->flags);
 
 	fdesc = find_file_desc(e);
 	if (fdesc == NULL) {
@@ -1230,6 +1236,7 @@ static int open_fd(struct fdinfo_list_entry *fle)
 	int new_fd = -1, ret;
 	struct chrfile_info *ci;
 
+	pr_info("open file flags: %#x\n", fle->fe->flags);
 	flem = file_master(d);
 	if (fle != flem) {
 		BUG_ON(fle->stage != FLE_INITIALIZED);
@@ -1251,6 +1258,19 @@ static int open_fd(struct fdinfo_list_entry *fle)
 				return 0;
 			}
 		}
+	} else if (fle->fe->flags & O_REUSE) {
+		pr_info("find reuse file:%d\n", d->id);
+		ret = repair_reuse_file(d->id);
+		if (!ret) {
+			new_fd = get_reuse_file();
+			pr_info("get reuse file:%d\n", new_fd);
+			if (new_fd <= 0 || setup_and_serve_out(fle, new_fd) < 0) {
+				pr_err("setup reuse file fail\n");
+				return -1;
+			}
+			fle->stage = FLE_RESTORED;
+			return 0;
+		}
 	}
 
 	/*
diff --git a/criu/include/orphan-inode.h b/criu/include/orphan-inode.h
new file mode 100644
index 0000000..bc3b6ae
--- /dev/null
+++ b/criu/include/orphan-inode.h
@@ -0,0 +1,16 @@
+#ifndef __CRIU_ORPHAN_INODE_H__
+#define __CRIU_ORPHAN_INODE_H__
+
+#define ADD_REUSE_FILE_PATH	"/sys/kernel/add_reuse_file"
+#define REPAIR_REUSE_FILE_PATH	"/sys/kernel/repair_reuse_file"
+#define REUSE_FILE_PATH		"/sys/kernel/reuse_file"
+#define O_REUSE			0100000000
+
+extern int dst_pid;
+extern int need_reuse_flag;
+
+int add_reuse_file(u32 id, int fd, int pid);
+int repair_reuse_file(int id);
+int get_reuse_file(void);
+
+#endif /* __CRIU_ORPHAN_INODE_H__ */
diff --git a/criu/orphan-inode.c b/criu/orphan-inode.c
new file mode 100644
index 0000000..c4e38dc
--- /dev/null
+++ b/criu/orphan-inode.c
@@ -0,0 +1,71 @@
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "int.h"
+#include "log.h"
+#include "orphan-inode.h"
+
+int add_reuse_file(u32 id, int fd, int pid)
+{
+	int retval;
+	char buf[256] = {0};
+
+	retval = snprintf(buf, 256, "%u,%d,%d", id, fd, pid);
+	if (retval <= 0)
+		return -EFAULT;
+
+	fd = open(ADD_REUSE_FILE_PATH, O_WRONLY, 0);
+	if (fd < 0) {
+		pr_err("open file:%s fail\n", ADD_REUSE_FILE_PATH);
+		return fd;
+	}
+
+	retval = write(fd, buf, strlen(buf));
+	close(fd);
+
+	return retval < 0 ? -1 : 0;
+}
+
+int repair_reuse_file(int id)
+{
+	int retval, fd;
+	char buf[256] = {0};
+
+	retval = snprintf(buf, 256, "%u", id);
+	if (retval <= 0)
+		return -EFAULT;
+
+	fd = open(REPAIR_REUSE_FILE_PATH, O_WRONLY, 0);
+	if (fd < 0) {
+		pr_err("open file:%s fail\n", REPAIR_REUSE_FILE_PATH);
+		return fd;
+	}
+	retval = write(fd, buf, strlen(buf));
+
+	close(fd);
+	return retval < 0 ? -1 : 0;
+}
+
+int get_reuse_file(void)
+{
+	int fd;
+	ssize_t count;
+	int retval = -1;
+	char buf[32] = {0};
+
+	fd = open(REUSE_FILE_PATH, O_RDONLY , 0);
+	if (fd < 0) {
+		pr_err("open file:%s fail\n", REUSE_FILE_PATH);
+		return fd;
+	}
+
+	count = read(fd, buf, sizeof(buf));
+	if (count > 0)
+		retval = atoi(buf);
+
+	close(fd);
+	return retval;
+}
-- 
2.34.1