From 228e9f0567eebd4597bd1771fc4bf3650190cf3e Mon Sep 17 00:00:00 2001
From: zhanchengbin <zhanchengbin1@huawei.com>
Date: Thu, 24 Feb 2022 10:06:30 +0800
Subject: [PATCH] resize2fs: resize2fs disk hardlinks will be error

Resize2fs disk hardlinks which mounting after the same name as tmpfs
 filesystem it will be error. The items in /proc/mounts are traversed,
when you get to tmpfs, file!=mnt->mnt_fsname, therefore, the
stat(mnt->mnt_fsname, &st_buf) branch is used, however, the values of
 file_rdev and st_buf.st_rdev are the same, As a result, the system
mistakenly considers that disk is mounted to /root/tmp. As a result
, resize2fs fails.

example:
dev_name="/dev/sdc" (ps: a disk in you self)
mkdir /root/tmp
mkdir /root/mnt
mkfs.ext4 -F -b 1024 -E "resize=10000000" "${dev_name}" 32768
mount -t tmpfs "${dev_name}" /root/tmp
mount "${dev_name}" /root/tmp
ln "${dev_name}" "${dev_name}"-ln
resize2fs "${dev_name}"-ln 6G

Signed-off-by: zhanchengbin <zhanchengbin1@huawei.com>
Signed-off-by: guiyao <guiyao@huawei.com>
---
 lib/ext2fs/ismounted.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/lib/ext2fs/ismounted.c b/lib/ext2fs/ismounted.c
index aee7d72..463a82a 100644
--- a/lib/ext2fs/ismounted.c
+++ b/lib/ext2fs/ismounted.c
@@ -98,6 +98,7 @@ static errcode_t check_mntent_file(const char *mtab_file, const char *file,
 {
 	struct mntent 	*mnt;
 	struct stat	st_buf;
+	struct stat	dir_st_buf;
 	errcode_t	retval = 0;
 	dev_t		file_dev=0, file_rdev=0;
 	ino_t		file_ino=0;
@@ -144,8 +145,12 @@ static errcode_t check_mntent_file(const char *mtab_file, const char *file,
 		if (stat(mnt->mnt_fsname, &st_buf) == 0) {
 			if (ext2fsP_is_disk_device(st_buf.st_mode)) {
 #ifndef __GNU__
-				if (file_rdev && (file_rdev == st_buf.st_rdev))
-					break;
+				if (file_rdev && (file_rdev == st_buf.st_rdev)) {
+					if (stat(mnt->mnt_dir, &dir_st_buf) != 0)
+						continue;
+					if (file_rdev == dir_st_buf.st_dev)
+						break;
+				}
 				if (check_loop_mounted(mnt->mnt_fsname,
 						st_buf.st_rdev, file_dev,
 						file_ino) == 1)
-- 
1.8.3.1