afs: afs_unlink() doesn't need to check dentry->d_inode

Don't check that dentry->d_inode is valid in afs_unlink().  We should be
able to take that as given.

This caused Smatch to issue the following warning:

	fs/afs/dir.c:1392 afs_unlink() error: we previously assumed 'vnode' could be null (see line 1375)
Reported-by: Nkbuild test robot <lkp@intel.com>
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NDavid Howells <dhowells@redhat.com>

fs/afs/dir.c

@@ -1394,7 +1394,8 @@ static int afs_unlink(struct inode *dir, struct dentry *dentry)
 {
 	struct afs_fs_cursor fc;
 	struct afs_status_cb *scb;
-	struct afs_vnode *dvnode = AFS_FS_I(dir), *vnode = NULL;
+	struct afs_vnode *dvnode = AFS_FS_I(dir);
+	struct afs_vnode *vnode = AFS_FS_I(d_inode(dentry));
 	struct key *key;
 	bool need_rehash = false;
 	int ret;
@@ -1417,15 +1418,12 @@ static int afs_unlink(struct inode *dir, struct dentry *dentry)
 	}
 
 	/* Try to make sure we have a callback promise on the victim. */
-	if (d_really_is_positive(dentry)) {
-		vnode = AFS_FS_I(d_inode(dentry));
-		ret = afs_validate(vnode, key);
-		if (ret < 0)
-			goto error_key;
-	}
+	ret = afs_validate(vnode, key);
+	if (ret < 0)
+		goto error_key;
 
 	spin_lock(&dentry->d_lock);
-	if (vnode && d_count(dentry) > 1) {
+	if (d_count(dentry) > 1) {
 		spin_unlock(&dentry->d_lock);
 		/* Start asynchronous writeout of the inode */
 		write_inode_now(d_inode(dentry), 0);