fix default_file_splice_read()

Botched calculation of number of pages. As the result, we were dropping pieces when doing splice to pipe from e.g. 9p. Reported-by: Alexei Starovoitov <ast@kernel.org> Tested-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
mariux64 · Nov 27, 2016 · 8e54cad · 8e54cad
1 parent 3ad0e83
commit 8e54cad
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/fs/splice.c b/fs/splice.c
@@ -408,7 +408,8 @@ static ssize_t default_file_splice_read(struct file *in, loff_t *ppos,
 	if (res <= 0)
 		return -ENOMEM;
 
-	nr_pages = res / PAGE_SIZE;
+	BUG_ON(dummy);
+	nr_pages = DIV_ROUND_UP(res, PAGE_SIZE);
 
 	vec = __vec;
 	if (nr_pages > PIPE_DEF_BUFFERS) {