mnt: Turn mntns_get_root_fd into accepting mnt ns_id

The only exception (for now) is the irmap -- it should
operate on ns as well.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

files-reg.c

@@ -351,7 +351,7 @@ static void __rollback_link_remaps(bool do_unlink)
 		return;
 
 	list_for_each_entry_safe(rlb, tmp, &link_remaps, list) {
-		mntns_root = mntns_get_root_fd(rlb->mnt_ns->pid);
+		mntns_root = mntns_get_root_fd(rlb->mnt_ns);
 		if (mntns_root < 0)
 			return;
 		list_del(&rlb->list);
@@ -407,7 +407,7 @@ static int create_link_remap(char *path, int len, int lfd,
 	/* Any 'unique' name works here actually. Remap works by reg-file ids. */
 	snprintf(tmp + 1, sizeof(link_name) - (size_t)(tmp - link_name - 1), "link_remap.%d", rfe.id);
 
-	mntns_root = mntns_get_root_fd(nsid->pid);
+	mntns_root = mntns_get_root_fd(nsid);
 
 	if (linkat(lfd, "", mntns_root, link_name, AT_EMPTY_PATH) < 0) {
 		pr_perror("Can't link remap to %s", path);
@@ -515,7 +515,7 @@ static int check_path_remap(char *rpath, int plen, const struct fd_parms *parms,
 		return dump_linked_remap(rpath + 1, plen - 1, ost, lfd, id, nsid);
 	}
 
-	mntns_root = mntns_get_root_fd(nsid->pid);
+	mntns_root = mntns_get_root_fd(nsid);
 	if (mntns_root < 0)
 		return -1;
 
@@ -713,7 +713,7 @@ static int do_open_reg_noseek_flags(struct reg_file_info *rfi, void *arg)
 	if (nsid == NULL)
 		return -1;
 
-	mntns_root = mntns_get_root_fd(nsid->pid);
+	mntns_root = mntns_get_root_fd(nsid);
 
 	fd = openat(mntns_root, rfi->path, flags);
 	if (fd < 0) {

include/mount.h

@@ -3,7 +3,9 @@
 
 extern struct mount_info *mntinfo;
 
-extern int mntns_get_root_fd(pid_t pid);
+struct ns_id;
+extern int __mntns_get_root_fd(pid_t pid);
+extern int mntns_get_root_fd(struct ns_id *ns);
 extern struct ns_id *lookup_nsid_by_mnt_id(int mnt_id);
 
 struct proc_mountinfo;
@@ -12,7 +14,6 @@ extern int open_mount(unsigned int s_dev);
 extern struct fstype *find_fstype_by_name(char *fst);
 
 struct cr_fdset;
-struct ns_id;
 extern struct mount_info * collect_mntinfo(struct ns_id *ns);
 extern int prepare_mnt_ns(void);
 

irmap.c

@@ -227,7 +227,7 @@ char *irmap_lookup(unsigned int s_dev, unsigned long i_ino)
 
 	pr_debug("Resolving %x:%lx path\n", s_dev, i_ino);
 
-	if (mntns_get_root_fd(root_item->pid.real) < 0)
+	if (__mntns_get_root_fd(root_item->pid.real) < 0)
 		goto out;
 
 	timing_start(TIME_IRMAP_RESOLVE);

mount.c

@@ -475,7 +475,7 @@ static int __open_mountpoint(struct mount_info *pm, int mnt_fd)
 	if (mnt_fd == -1) {
 		int mntns_root;
 
-		mntns_root = mntns_get_root_fd(pm->nsid->pid);
+		mntns_root = mntns_get_root_fd(pm->nsid);
 		if (mntns_root < 0)
 			return -1;
 
@@ -1794,7 +1794,7 @@ out:
 	return ret;
 }
 
-int mntns_get_root_fd(pid_t pid)
+int __mntns_get_root_fd(pid_t pid)
 {
 	static int mntns_root_pid = -1;
 
@@ -1859,6 +1859,11 @@ set_root:
 	return ret;
 }
 
+int mntns_get_root_fd(struct ns_id *mntns)
+{
+	return __mntns_get_root_fd(mntns->pid);
+}
+
 struct ns_id *lookup_nsid_by_mnt_id(int mnt_id)
 {
 	struct mount_info *mi;

sk-unix.c

@@ -375,7 +375,7 @@ static int unix_collect_one(const struct unix_diag_msg *m,
 	if (ns == NULL)
 		return -1;
 
-	if (mntns_get_root_fd(ns->pid) < 0)
+	if (mntns_get_root_fd(ns) < 0)
 		return -1;
 
 	d = xzalloc(sizeof(*d));