scatterlist: don't BUG when we can trivially return a proper error.

There is absolutely no reason to crash the kernel when we have a
perfectly good return value already available to use for conveying
failure status.

Let's return an error code instead of crashing the kernel: that sounds
like a much better plan.

[[email protected]: s/E2BIG/EINVAL/]
Signed-off-by: Nick Bowler <[email protected]>
Cc: Maxim Levitsky <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Jens Axboe <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index 3675452b..7874b01 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -248,7 +248,8 @@
 	unsigned int left;
 
 #ifndef ARCH_HAS_SG_CHAIN
-	BUG_ON(nents > max_ents);
+	if (WARN_ON_ONCE(nents > max_ents))
+		return -EINVAL;
 #endif
 
 	memset(table, 0, sizeof(*table));