fusefs: handle evil servers that return illegal inode numbers
- If during FUSE_CREATE, FUSE_MKDIR, etc the server returns the same inode number for the new file as for its parent directory, reject it. Previously this would triggers a recurse-on-non-recursive lock panic.
- If during FUSE_LINK the server returns a different inode number for the new name as for the old one, reject it. Obviously, that can't be a hard link.
- If during FUSE_LOOKUP the server returns the same inode number for the new file as for its parent directory, reject it. Nothing good can come of this.
PR: 263662
Reported by: Robert Morris <rtm@lcs.mit.edu>
MFC after: 2 weeks