[LU-7177] First write RPC may set stale ownership to the OST object

• Type: Bug
• Resolution: Not a Bug
• Priority: Minor
• Severity: 3
• Assignee: Niu Yawei (Inactive)
• Reporter: Niu Yawei (Inactive)

Description

When the first write RPC arrives OST, it calls ofd_write_attr_set() -> ofd_attr_handle_ugid() to check if S_ISUID or S_ISGID is present, if the flag is present, it assumes the object is just pre-created without proper uid/gid setting, and it'll set the uid/gid carried from client to initialize the ownership of the object.

However, there isn't any locking in ofd_attr_handle_ugid() to serialize the ownership changing by first write and real chown/chgrp calls, that could lead to the first write overwrite the correct ownership set by chown/chgrp with stale one.

I think a ofd_write_lock() could be introduced in ofd_attr_handle_ugid() to eliminate such race.