lib/scatterlist: fix memory leak with scsi-mq

Fix a memory leak with scsi-mq triggered by commands with large data
transfer length.

Fixes: c53c6d6a68b1 ("scatterlist: allow chaining to preallocated chunks")
Cc: <stable@vger.kernel.org> # 3.17.x
Signed-off-by: Tony Battersby <tonyb@cybernetics.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

lib/scatterlist.c

@@ -203,10 +203,10 @@ void __sg_free_table(struct sg_table *table, unsigned int max_ents,
 		}
 
 		table->orig_nents -= sg_size;
-		if (!skip_first_chunk) {
-			free_fn(sgl, alloc_size);
+		if (skip_first_chunk)
 			skip_first_chunk = false;
-		}
+		else
+			free_fn(sgl, alloc_size);
 		sgl = next;
 	}