[patch] aio: make aio_ring_info->nr_pages an unsigned int

From: Chen, Kenneth W
Date: Fri Dec 29 2006 - 22:16:55 EST

The number of io_event in AIO event queue allowed currently is no more
than 2^32-1, because the syscall defines:

asmlinkage long sys_io_setup(unsigned nr_events, aio_context_t __user *ctxp)

We internally allocate a ring buffer for nr_events and keeps tracks of
page descriptors for each of these ring buffer pages. Since page size
is significantly larger than AIO event size (4096 versus 32), I don't
think it is ever possible to overflow nr_pages in 32-bit quantity.

This patch changes nr_pages to unsigned int. on 64-bit arch, changing
it to unsigned int also allows better packing of aio_ring_info structure.

Signed-off-by: Ken Chen <kenneth.w.chen@xxxxxxxxx>

--- ./include/linux/aio.h.orig 2006-12-24 22:31:55.000000000 -0800
+++ ./include/linux/aio.h 2006-12-24 22:41:28.000000000 -0800
@@ -165,7 +165,7 @@ struct aio_ring_info {

struct page **ring_pages;
spinlock_t ring_lock;
- long nr_pages;
+ unsigned nr_pages;

unsigned nr, tail;

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