fuse: BUG_ON correction in fuse_dev_splice_write()

commit 9635453 ("fuse: reduce allocation size for splice_write")
changed size of bufs array, so BUG_ON which checks the index of the array
shold also be fixed.

[SzM: turn BUG_ON into WARN_ON]

Fixes: 9635453 ("fuse: reduce allocation size for splice_write")
Signed-off-by: Vasily Averin <[email protected]>
Signed-off-by: Miklos Szeredi <[email protected]>

Author: vaverin

fs/fuse/dev.c

@@ -1977,8 +1977,9 @@ static ssize_t fuse_dev_splice_write(struct pipe_inode_info *pipe,
 		struct pipe_buffer *ibuf;
 		struct pipe_buffer *obuf;
 
-		BUG_ON(nbuf >= pipe->ring_size);
-		BUG_ON(tail == head);
+		if (WARN_ON(nbuf >= count || tail == head))
+			goto out_free;
+
 		ibuf = &pipe->bufs[tail & mask];
 		obuf = &bufs[nbuf];