btrfs: remove unnecessary NULL check for the new inode during rename exchange

At the very end of btrfs_rename_exchange(), in case an error happened, we
are checking if 'new_inode' is NULL, but that is not needed since during a
rename exchange, unlike regular renames, 'new_inode' can never be NULL,
and if it were, we would have a crashed much earlier when we dereference it
multiple times.

So remove the check because it is not necessary and because it is causing
static checkers to emit a warning. I probably introduced the check by
copy-pasting similar code from btrfs_rename(), where 'new_inode' can be
NULL, in commit 86e8aa0e ("Btrfs: unpin logs if rename exchange
operation fails").
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/inode.c

@@ -9523,8 +9523,7 @@ static int btrfs_rename_exchange(struct inode *old_dir,
 		if (btrfs_inode_in_log(BTRFS_I(old_dir), fs_info->generation) ||
 		    btrfs_inode_in_log(BTRFS_I(new_dir), fs_info->generation) ||
 		    btrfs_inode_in_log(BTRFS_I(old_inode), fs_info->generation) ||
-		    (new_inode &&
-		     btrfs_inode_in_log(BTRFS_I(new_inode), fs_info->generation)))
+		    btrfs_inode_in_log(BTRFS_I(new_inode), fs_info->generation))
 			btrfs_set_log_full_commit(trans);
 
 		if (root_log_pinned) {