2022-01-04 14:23:56

by zhanchengbin

[permalink] [raw]
Subject: [PATCH v2] 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 "${dev_name}" /root/mnt
ln "${dev_name}" "${dev_name}"-ln
resize2fs "${dev_name}"-ln 6G

Signed-off-by: zhanchengbin <[email protected]>
Signed-off-by: Zhiqiang Liu <[email protected]>

---
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 aee7d726..463a82a6 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)
--
2.27.0