[RFC PATCH 1/2] watch_queue: Fix pipe buffer allocation

[Eric Sandeen <sandeen@xxxxxxxxxx>]

It seems that watch_queue_set_size() calls pipe_resize_ring() with the
number of notifications in play, not the number of pages required to
hold those notifications, as pipe_resize_ring() expects. Change from
nr_notes to nr_pages to fix this.

Fixes: c73be61cede58 ("pipe: Add general notification queue support")
Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
---

diff --git a/kernel/watch_queue.c b/kernel/watch_queue.c
index 5267adeaa403..10b4d311e930 100644
--- a/kernel/watch_queue.c
+++ b/kernel/watch_queue.c
@@ -254,6 +254,8 @@ long watch_queue_set_size(struct pipe_inode_info *pipe, unsigned int nr_notes)
 
 	nr_pages = (nr_notes + WATCH_QUEUE_NOTES_PER_PAGE - 1);
 	nr_pages /= WATCH_QUEUE_NOTES_PER_PAGE;
+	/* Round nr_notes up to fill the pages */
+	nr_notes = nr_pages * WATCH_QUEUE_NOTES_PER_PAGE;
 	user_bufs = account_pipe_buffers(pipe->user, pipe->nr_accounted, nr_pages);
 
 	if (nr_pages > pipe->max_usage &&
@@ -264,8 +266,7 @@ long watch_queue_set_size(struct pipe_inode_info *pipe, unsigned int nr_notes)
 		goto error;
 	}
 
-	nr_notes = nr_pages * WATCH_QUEUE_NOTES_PER_PAGE;
-	ret = pipe_resize_ring(pipe, roundup_pow_of_two(nr_notes));
+	ret = pipe_resize_ring(pipe, nr_pages);
 	if (ret < 0)
 		goto error;