blk-merge: warn if figured out segment number is bigger than nr_phys_segments
We had seen lots of reports of this kind issue, so add one
warnning in blk-merge, then it can be triggered easily and
avoid to depend on warning/bug from drivers.
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 50793cd..41a55ba 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -428,6 +428,12 @@
if (sg)
sg_mark_end(sg);
+ /*
+ * Something must have been wrong if the figured number of
+ * segment is bigger than number of req's physical segments
+ */
+ WARN_ON(nsegs > rq->nr_phys_segments);
+
return nsegs;
}
EXPORT_SYMBOL(blk_rq_map_sg);