s_inodes is superblock-specific resource, which should be
protected by sb's specific lock s_inode_list_lock.
v2: update the locking mechanisim to protect mutual-exclusive access
both for s_inode_list_lock & erofs_fscache_domain_init_cookie(), as the
reviewing comments from Jia Zhu.
v1: https://lore.kernel.org/all/TYCP286MB23237A9993E0FFCFE5C2BDBECA269@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/
base-commit: 8436c4a57bd147b0bd2943ab499bb8368981b9e1
Signed-off-by: Dawei Li <set_pte_at@xxxxxxxxxxx>