[PATCH v22 06/31] splice: Check for zero count in vfs_splice_read()

[David Howells <dhowells@xxxxxxxxxx>]

Make vfs_splice_read() return immediately if the length is 0.

Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Christian Brauner <brauner@xxxxxxxxxx>
cc: Jens Axboe <axboe@xxxxxxxxx>
cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
cc: linux-block@xxxxxxxxxxxxxxx
cc: linux-fsdevel@xxxxxxxxxxxxxxx
cc: linux-mm@xxxxxxxxx
---
 fs/splice.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/splice.c b/fs/splice.c
index d815a69f6589..fe3309ffeb26 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -891,6 +891,8 @@ long vfs_splice_read(struct file *in, loff_t *ppos,
 
 	if (unlikely(!(in->f_mode & FMODE_READ)))
 		return -EBADF;
+	if (!len)
+		return 0;
 
 	/* Don't try to read more the pipe has space for. */
 	p_space = pipe->max_usage - pipe_occupancy(pipe->head, pipe->tail);