[CRIU] [PATCH 5/7] tty: Save mount ids for terminals into image

[Cyrill Gorcunov]

Since we're gonna to handle several devpts instance
each terminal need a second key to separate same
named pairs in different mounts. For this sake
each tty assigned with mount id.

Note to restore them properly we need per mount
bitmaps to track pairs and indices, which will be
addressed in next patch.

Signed-off-by: Cyrill Gorcunov <gorcunov at openvz.org>
---
 criu/mount.c     | 16 ++++++++++++++--
 criu/tty.c       | 33 ++++++++++++++++++++++++++++++---
 images/tty.proto |  4 ++++
 3 files changed, 48 insertions(+), 5 deletions(-)

diff --git a/criu/mount.c b/criu/mount.c
index fb6825b38fa9..15ce303bbdbb 100644
--- a/criu/mount.c
+++ b/criu/mount.c
@@ -234,6 +234,18 @@ struct mount_info *lookup_mnt_sdev(unsigned int s_dev)
 	return NULL;
 }
 
+static struct mount_info *lookup_mnt_sdev_on_root(unsigned int s_dev)
+{
+	struct mount_info *m;
+
+	for (m = mntinfo; m != NULL; m = m->next)
+		if (m->s_dev == s_dev &&
+		    is_root(m->root))
+			return m;
+
+	return NULL;
+}
+
 static struct mount_info *mount_resolve_path(struct mount_info *mntinfo_tree, const char *path)
 {
 	size_t pathlen = strlen(path);
@@ -278,7 +290,7 @@ int mount_resolve_devpts_mnt_id(int s_dev)
 {
 	struct mount_info *mi;
 
-	mi = lookup_mnt_sdev(s_dev);
+	mi = lookup_mnt_sdev_on_root(s_dev);
 	if (!mi) {
 		pr_err("No devpts mount point found for s_dev %#x\n", s_dev);
 		return -1;
@@ -289,7 +301,7 @@ int mount_resolve_devpts_mnt_id(int s_dev)
 	} else if (mi->fstype->code == FSTYPE__DEVTMPFS) {
 		char path[PATH_MAX];
 
-		snprintf(path, sizeof(path), "%s/pts", mi->mountpoint + 1);
+		snprintf(path, sizeof(path), "%s/pts/ptmx", mi->mountpoint + 1);
 		mi = mount_resolve_path(mi, path);
 		if (!mi) {
 			pr_err("Can't resolve %s\n", path);
diff --git a/criu/tty.c b/criu/tty.c
index fe249a3caa43..064395eaf870 100644
--- a/criu/tty.c
+++ b/criu/tty.c
@@ -28,6 +28,7 @@
 #include "files-reg.h"
 #include "namespaces.h"
 #include "external.h"
+#include "mount.h"
 
 #include "protobuf.h"
 #include "util.h"
@@ -1470,6 +1471,11 @@ static int collect_one_tty_info_entry(void *obj, ProtobufCMessage *msg, struct c
 
 	info->tie = pb_msg(msg, TtyInfoEntry);
 
+	if (!info->tie->has_mnt_id) {
+		info->tie->has_mnt_id = true;
+		info->tie->mnt_id = 0;
+	}
+
 	switch (info->tie->type) {
 	case TTY_TYPE__PTY:
 		if (!info->tie->pty) {
@@ -1514,6 +1520,11 @@ static int collect_one_tty(void *obj, ProtobufCMessage *msg, struct cr_img *i)
 
 	info->tfe = pb_msg(msg, TtyFileEntry);
 
+	if (!info->tfe->has_mnt_id) {
+		info->tfe->has_mnt_id = true;
+		info->tfe->mnt_id = 0;
+	}
+
 	info->tie = lookup_tty_info_entry(info->tfe->tty_info_id);
 	if (!info->tie) {
 		pr_err("No tty-info-id %#x found on id %#x\n",
@@ -1673,7 +1684,8 @@ int dump_verify_tty_sids(void)
 	return ret;
 }
 
-static int dump_tty_info(int lfd, u32 id, const struct fd_parms *p, struct tty_driver *driver, int index)
+static int dump_tty_info(int lfd, u32 id, const struct fd_parms *p, int mnt_id,
+			 struct tty_driver *driver, int index)
 {
 	TtyInfoEntry info		= TTY_INFO_ENTRY__INIT;
 	TermiosEntry termios		= TERMIOS_ENTRY__INIT;
@@ -1741,6 +1753,9 @@ static int dump_tty_info(int lfd, u32 id, const struct fd_parms *p, struct tty_d
 	info.has_gid		= true;
 	info.gid		= userns_gid(p->stat.st_gid);
 
+	info.has_mnt_id		= true;
+	info.mnt_id		= mnt_id;
+
 	info.type = driver->type;
 	if (info.type == TTY_TYPE__PTY) {
 		info.pty	= &pty;
@@ -1809,7 +1824,7 @@ out:
 static int dump_one_tty(int lfd, u32 id, const struct fd_parms *p)
 {
 	TtyFileEntry e = TTY_FILE_ENTRY__INIT;
-	int ret = 0, index = -1;
+	int ret = 0, index = -1, mnt_id;
 	struct tty_driver *driver;
 
 	pr_info("Dumping tty %d with id %#x\n", lfd, id);
@@ -1833,6 +1848,18 @@ static int dump_one_tty(int lfd, u32 id, const struct fd_parms *p)
 	e.flags		= p->flags;
 	e.fown		= (FownEntry *)&p->fown;
 
+	if (is_pty(driver)) {
+		mnt_id = mount_resolve_devpts_mnt_id(p->stat.st_dev);
+		if (mnt_id < 0) {
+			pr_info("Can't obtain mnt_id on tty %d id %#x\n", lfd, id);
+			return -1;
+		}
+	} else
+		mnt_id = p->mnt_id;
+
+	e.has_mnt_id	= true;
+	e.mnt_id	= mnt_id;
+
 	/*
 	 * FIXME
 	 *
@@ -1854,7 +1881,7 @@ static int dump_one_tty(int lfd, u32 id, const struct fd_parms *p)
 	 */
 
 	if (!tty_test_and_set(e.tty_info_id, tty_bitmap))
-		ret = dump_tty_info(lfd, e.tty_info_id, p, driver, index);
+		ret = dump_tty_info(lfd, e.tty_info_id, p, mnt_id, driver, index);
 
 	if (!ret)
 		ret = pb_write_one(img_from_set(glob_imgset, CR_FD_TTY_FILES), &e, PB_TTY_FILE);
diff --git a/images/tty.proto b/images/tty.proto
index 739a4ffedfff..dae23a38669b 100644
--- a/images/tty.proto
+++ b/images/tty.proto
@@ -73,6 +73,8 @@ message tty_info_entry {
 
 	optional uint32			uid		= 14;
 	optional uint32			gid		= 15;
+
+	optional sint32			mnt_id		= 16 [default = -1];
 };
 
 message tty_file_entry {
@@ -81,4 +83,6 @@ message tty_file_entry {
 
 	required uint32			flags		= 3 [(criu).hex = true];
 	required fown_entry		fown		= 4;
+
+	optional sint32			mnt_id		= 5 [default = -1];
 }
-- 
2.7.4