fs: Move info about cwd into separate file

Why? Because one day we'll support various CLONE_ flags and
for fdtable and fs info we'd like to have separate images (since
these objects are separate in kernel).
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

cr-dump.c

@@ -348,21 +348,6 @@ static int dump_task_special_files(pid_t pid, const struct cr_fdset *cr_fdset)
 	struct fd_parms params;
 	int fd, ret;
 
-	/* Dump /proc/pid/cwd */
-	params = (struct fd_parms) {
-		.id		= FD_ID_INVALID,
-		.pid		= FD_PID_INVALID,
-		.type		= FDINFO_CWD,
-	};
-
-	fd = open_proc(pid, "cwd");
-	if (fd < 0)
-		return -1;
-	ret = do_dump_one_fdinfo(&params, fd, cr_fdset);
-	close(fd);
-	if (ret)
-		return ret;
-
 	/* Dump /proc/pid/exe */
 	params = (struct fd_parms) {
 		.id		= FD_ID_INVALID,
@@ -488,6 +473,36 @@ err:
 	return ret;
 }
 
+static int dump_task_fs(pid_t pid, struct cr_fdset *fdset)
+{
+	struct fd_parms p;
+	struct fs_entry fe;
+	int fd, ret;
+
+	fd = open_proc(pid, "cwd");
+	if (fd < 0)
+		return -1;
+
+	if (fstat(fd, &p.stat) < 0) {
+		pr_perror("Can't stat cwd");
+		return -1;
+	}
+
+	p.type = FDINFO_REG;
+	p.flags = 0;
+	p.pos = 0;
+	fe.cwd_id = fd_id_generate_special();
+
+	ret = dump_one_reg_file(fd, fe.cwd_id, &p);
+	if (!ret) {
+		pr_info("Dumping task cwd id %x\n", fe.cwd_id);
+		ret = write_img(fdset_fd(fdset, CR_FD_FS), &fe);
+	}
+
+	close(fd);
+	return ret;
+}
+
 struct shmem_info
 {
 	unsigned long	size;
@@ -1452,6 +1467,13 @@ static int dump_one_task(const struct pstree_item *item)
 		pr_err("Dump creds (pid: %d) failed with %d\n", pid, ret);
 		goto err;
 	}
+
+	ret = dump_task_fs(pid, cr_fdset);
+	if (ret) {
+		pr_err("Dump fs (pid: %d) failed with %d\n", pid, ret);
+		goto err;
+	}
+
 err:
 	close_cr_fdset(&cr_fdset);
 	close_pid_proc();

cr-restore.c

@@ -510,6 +510,9 @@ static int restore_one_alive_task(int pid)
 	if (prepare_fds(pid))
 		return -1;
 
+	if (prepare_fs(pid))
+		return -1;
+
 	if (prepare_sigactions(pid))
 		return -1;
 

cr-show.c

@@ -59,7 +59,6 @@ static char *fdtype2s(u8 type)
 	static char und[4];
 	static char *fdtypes[] = {
 		[FDINFO_REG] = "reg",
-		[FDINFO_CWD] = "cwd",
 		[FDINFO_EXE] = "exe",
 		[FDINFO_INETSK] = "isk",
 		[FDINFO_PIPE] = "pipe",
@@ -172,6 +171,18 @@ out:
 	pr_img_tail(CR_FD_PIPES);
 }
 
+void show_fs(int fd_fs, struct cr_options *o)
+{
+	struct fs_entry fe;
+
+	pr_img_head(CR_FD_FS);
+
+	if (read_img(fd_fs, &fe) > 0)
+		pr_msg("CWD: %x\n", fe.cwd_id);
+
+	pr_img_tail(CR_FD_FS);
+}
+
 void show_vmas(int fd_vma, struct cr_options *o)
 {
 	struct vma_area vma_area = {};

crtools.c

@@ -170,6 +170,12 @@ struct cr_fd_desc_tmpl fdset_template[CR_FD_MAX] = {
 		.magic	= IPCNS_SEM_MAGIC,
 		.show	= show_ipc_sem,
 	},
+
+	[CR_FD_FS] = {
+		.fmt	= FMT_FNAME_FS,
+		.magic	= FS_MAGIC,
+		.show	= show_fs,
+	},
 };
 
 static struct cr_fdset *alloc_cr_fdset(int nr)

files.c

@@ -259,23 +259,6 @@ static int find_open_fe_fd(struct fdinfo_entry *fe)
 	return open_fe_fd(&rfi->d);
 }
 
-static int restore_cwd(struct fdinfo_entry *fe, int fd)
-{
-	int cfd;
-
-	cfd = find_open_fe_fd(fe);
-	if (cfd < 0)
-		return cfd;
-
-	if (fchdir(cfd)) {
-		pr_perror("Can't chdir");
-		return -1;
-	}
-
-	close(cfd);
-	return 0;
-}
-
 int self_exe_fd;
 
 static int restore_exe_early(struct fdinfo_entry *fe, int fd)
@@ -493,8 +476,6 @@ static int open_special_fdinfo(int pid, struct fdinfo_entry *fe,
 	if (state != FD_STATE_RECV)
 		return 0;
 
-	if (fe->type == FDINFO_CWD)
-		return restore_cwd(fe, fdinfo_fd);
 	if (fe->type == FDINFO_EXE)
 		return restore_exe_early(fe, fdinfo_fd);
 
@@ -550,6 +531,41 @@ int prepare_fds(int pid)
 	return run_unix_connections();
 }
 
+int prepare_fs(int pid)
+{
+	int ifd, cwd;
+	struct fs_entry fe;
+	struct file_desc *fd;
+
+	ifd = open_image_ro(CR_FD_FS, pid);
+	if (ifd < 0)
+		return -1;
+
+	if (read_img(ifd, &fe) < 0)
+		return -1;
+
+	fd = find_file_desc_raw(FDINFO_REG, fe.cwd_id);
+	if (fd == NULL) {
+		pr_err("Can't find file for %d's cwd (%x)\n",
+				pid, fe.cwd_id);
+		return -1;
+	}
+
+	cwd = open_fe_fd(fd);
+	if (cwd < 0)
+		return -1;
+
+	if (fchdir(cwd) < 0) {
+		pr_perror("Can't change root");
+		return -1;
+	}
+
+	close(cwd);
+	close(ifd);
+
+	return 0;
+}
+
 int get_filemap_fd(int pid, struct vma_entry *vma_entry)
 {
 	struct file_desc *fd;

include/crtools.h

@@ -26,6 +26,7 @@ enum {
 	CR_FD_SIGACT,
 	CR_FD_ITIMERS,
 	CR_FD_CREDS,
+	CR_FD_FS,
 	_CR_FD_TASK_TO,
 
 	/*
@@ -90,6 +91,7 @@ void show_pstree(int fd_pstree, struct cr_options *o);
 void show_sigacts(int fd_sigacts, struct cr_options *o);
 void show_itimers(int fd, struct cr_options *o);
 void show_creds(int fd, struct cr_options *o);
+void show_fs(int fd, struct cr_options *o);
 
 extern struct cr_fd_desc_tmpl fdset_template[CR_FD_MAX];
 
@@ -113,6 +115,7 @@ extern struct cr_fd_desc_tmpl fdset_template[CR_FD_MAX];
 #define FMT_FNAME_IPCNS_MSG	"ipcns-msg-%d.img"
 #define FMT_FNAME_IPCNS_SEM	"ipcns-sem-%d.img"
 #define FMT_FNAME_SK_QUEUES	"sk-queues.img"
+#define FMT_FNAME_FS		"fs-%d.img"
 
 extern int open_image_dir(void);
 extern void close_image_dir(void);

include/files.h

@@ -66,6 +66,7 @@ extern int prepare_fds(int pid);
 extern int prepare_fd_pid(int pid);
 extern int prepare_shared_fdinfo(void);
 extern int get_filemap_fd(int pid, struct vma_entry *vma_entry);
+extern int prepare_fs(int pid);
 
 extern int self_exe_fd;
 

include/image.h

@@ -28,6 +28,7 @@
 #define IPCNS_MSG_MAGIC	0x55453737 /* Moscow */
 #define IPCNS_SEM_MAGIC	0x59573019 /* St. Petersburg */
 #define REG_FILES_MAGIC	0x50363636 /* Belgorod */
+#define FS_MAGIC	0x51403912 /* Voronezh */
 
 #define PIPEFS_MAGIC	0x50495045
 
@@ -37,7 +38,6 @@ enum fd_types {
 	FDINFO_PIPE,
 	FDINFO_INETSK,
 	FDINFO_UNIXSK,
-	FDINFO_CWD,
 	FDINFO_EXE,
 
 	FD_INFO_MAX
@@ -61,9 +61,11 @@ struct fdinfo_entry {
 	u32	id;
 } __packed;
 
-#define fd_is_special(fe) (		\
-	 ((fe)->type == FDINFO_CWD) ||	\
-	 ((fe)->type == FDINFO_EXE))
+#define fd_is_special(fe) ((fe)->type == FDINFO_EXE)
+
+struct fs_entry {
+	u32	cwd_id;
+} __packed;
 
 struct pstree_entry {
 	u32	pid;