f2fs: don't set RO when shutting down f2fs

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: f2fs: don't set RO when shutting down f2fs Shutdown does not check the error of thaw_super due to readonly, which causes a deadlock like below. f2fs_ioc_shutdown(F2FS_GOING_DOWN_FULLSYNC) issue_discard_thread - bdev_freeze - freeze_super - f2fs_stop_checkpoint() - f2fs_handle_critical_error - sb_start_write - set RO - waiting - bdev_thaw - thaw_super_locked - return -EINVAL, if sb_rdonly() - f2fs_stop_discard_thread -> wait for kthread_stop(discard_thread);

References

• https://git.kernel.org/stable/c/1036d3ea7a32cb7cee00885c73a1f2ba7fbc499a
• https://git.kernel.org/stable/c/f47ed3b284b38f235355e281f57dfa8fffcc6563
• https://git.kernel.org/stable/c/3bdb7f161697e2d5123b89fe1778ef17a44858e7