afs: Fix afs_do_lookup() to call correct fetch-status op variant

Fix afs_do_lookup()'s fallback case for when FS.InlineBulkStatus isn't
supported by the server.

In the fallback, it calls FS.FetchStatus for the specific vnode it's
meant to be looking up.  Commit b6489a49 broke this by renaming one
of the two identically-named afs_fetch_status_operation descriptors to
something else so that one of them could be made non-static.  The site
that used the renamed one, however, wasn't renamed and didn't produce
any warning because the other was declared in a header.

Fix this by making afs_do_lookup() use the renamed variant.

Note that there are two variants of the success method because one is
called from ->lookup() where we may or may not have an inode, but can't
call iget until after we've talked to the server - whereas the other is
called from within iget where we have an inode, but it may or may not be
initialised.

The latter variant expects there to be an inode, but because it's being
called from there former case, there might not be - resulting in an oops
like the following:

  BUG: kernel NULL pointer dereference, address: 00000000000000b0
  ...
  RIP: 0010:afs_fetch_status_success+0x27/0x7e
  ...
  Call Trace:
    afs_wait_for_operation+0xda/0x234
    afs_do_lookup+0x2fe/0x3c1
    afs_lookup+0x3c5/0x4bd
    __lookup_slow+0xcd/0x10f
    walk_component+0xa2/0x10c
    path_lookupat.isra.0+0x80/0x110
    filename_lookup+0x81/0x104
    vfs_statx+0x76/0x109
    __do_sys_newlstat+0x39/0x6b
    do_syscall_64+0x4c/0x78
    entry_SYSCALL_64_after_hwframe+0x44/0xa9

Fixes: b6489a49 ("afs: Fix silly rename")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/afs/dir.c

@@ -845,7 +845,7 @@ static struct inode *afs_do_lookup(struct inode *dir, struct dentry *dentry,
 		 * to FS.FetchStatus for op->file[1].
 		 */
 		op->fetch_status.which = 1;
-		op->ops = &afs_fetch_status_operation;
+		op->ops = &afs_lookup_fetch_status_operation;
 		afs_begin_vnode_operation(op);
 		afs_wait_for_operation(op);
 	}