On 14.02.2008 [16:14:33 +0100], Julia Lawall wrote:
> From: Julia Lawall <[EMAIL PROTECTED]>
>
> The kernel.h macro DIV_ROUND_UP performs the computation (((n) + (d) - 1) /
> (d)) but is perhaps more readable.
>
> An extract of the semantic patch that makes this change is as follows:
> (http://www.emn.fr/x-info/coccinelle/)
>
> // <smpl>
> @haskernel@
> @@
>
> #include <linux/kernel.h>
>
> @depends on haskernel@
> expression n,d;
> @@
>
> (
> - (n + d - 1) / d
> + DIV_ROUND_UP(n,d)
> |
> - (n + (d - 1)) / d
> + DIV_ROUND_UP(n,d)
> )
>
> @depends on haskernel@
> expression n,d;
> @@
>
> - DIV_ROUND_UP((n),d)
> + DIV_ROUND_UP(n,d)
>
> @depends on haskernel@
> expression n,d;
> @@
>
> - DIV_ROUND_UP(n,(d))
> + DIV_ROUND_UP(n,d)
> // </smpl>
>
> Signed-off-by: Julia Lawall <[EMAIL PROTECTED]>
>
> ---
>
> diff -u -p a/fs/direct-io.c b/fs/direct-io.c
> --- a/fs/direct-io.c 2008-02-08 08:58:17.000000000 +0100
> +++ b/fs/direct-io.c 2008-02-13 20:58:53.000000000 +0100
> @@ -976,7 +976,7 @@ direct_io_worker(int rw, struct kiocb *i
> for (seg = 0; seg < nr_segs; seg++) {
> user_addr = (unsigned long)iov[seg].iov_base;
> dio->pages_in_io +=
> - ((user_addr+iov[seg].iov_len +PAGE_SIZE-1)/PAGE_SIZE
> + (DIV_ROUND_UP(user_addr + iov[seg].iov_len, PAGE_SIZE)
> - user_addr/PAGE_SIZE);
Is it just me, or does
((user_addr + iov[seg].iov_len + PAGE_SIZE - 1)/PAGE_SIZE -
user_addr/PAGE_SIZE)
not simplify to
= ((iov[seg].iov_len + PAGE_SIZE - 1)/PAGE_SIZE + user_addr/PAGE_SIZE -
user_addr/PAGE_SIZE)
= ((iov[seg].iov_len + PAGE_SIZE - 1)/PAGE_SIZE)
= DIV_ROUND_UP(iov[seg].iov_len, PAGE_SIZE)
CMIIW.
Thanks,
Nish
--
Nishanth Aravamudan <[EMAIL PROTECTED]>
IBM Linux Technology Center
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