copy_to_user() returns the number of remaining bytes. Avoid that
a larger value is returned than the number of bytes that have
been copied by returning -EFAULT if not all bytes have been copied.

Signed-off-by: Bart Van Assche <redacted>
---
 drivers/md/bcache/debug.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/md/bcache/debug.c b/drivers/md/bcache/debug.c
index af89408befe8..376899cfcbf1 100644
--- a/drivers/md/bcache/debug.c
+++ b/drivers/md/bcache/debug.c

@@ -175,9 +175,8 @@ static ssize_t bch_dump_read(struct file *file, char __user *buf,
 		struct keybuf_key *w;
 		unsigned bytes = min(i->bytes, size);
 
-		int err = copy_to_user(buf, i->buf, bytes);
-		if (err)
-			return err;
+		if (copy_to_user(buf, i->buf, bytes))
+			return -EFAULT;
 
 		ret	 += bytes;
 		buf	 += bytes;

-- 
2.16.2