On 01/07/2012 05:30 AM, Wu Fengguang wrote:
> On Fri, Jan 06, 2012 at 03:01:09PM -0800, Linus Torvalds wrote:
>> On Thu, Jan 5, 2012 at 4:18 PM, Randy Dunlap <rdunlap@xxxxxxxxxxxx> wrote:
>>>
>>> In linux-next, fs/fs-writeback.c no longer #includes <linux/buffer_head.h>,
>>> which #included <linux/pagemap.h>, so add that latter header file to
>>> <linux/writeback.h> to fix the build error:
>>>
>>> fs/fs-writeback.c:510:11: error: 'PAGE_CACHE_SHIFT' undeclared (first use in this function)
>>
>> I would actually suggest:
>>
>> - move the whole MIN_WRITEBACK_PAGES #define from the header file to
>> fs/writeback.c
>
> Done.
>
>> (why expose such a random #define to outside users that
>> have nothing to do with it?)
>
> Yeah, there were some early patches that reference MIN_WRITEBACK_PAGES
> from other files, which are dropped later..
>
>> - make sure that fs/fs-writeback.c has that pagemap.h #include.
>
> Done. (otherwise it won't compile)
>
>> There's no reason why <linux/writeback.h> should include filemap.h per
>> se, and there is no reason why it should expose some internal chunking
>> #define to anybody else.
>
> Good point. I'll queue this patch to writeback-for-next:
>
> Subject: writeback: move MIN_WRITEBACK_PAGES to fs-writeback.c
> Date: Sat Jan 07 20:41:55 CST 2012
>
> Fix compile error
>
> fs/fs-writeback.c:515:33: error: ‘PAGE_CACHE_SHIFT’ undeclared (first use in this function)
>
> Reported-by: Randy Dunlap <rdunlap@xxxxxxxxxxxx>
> Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
Acked-by: Randy Dunlap <rdunlap@xxxxxxxxxxxx>
Thanks.
> ---
> fs/fs-writeback.c | 6 ++++++
> include/linux/writeback.h | 5 -----
> 2 files changed, 6 insertions(+), 5 deletions(-)
>
> --- next.orig/fs/fs-writeback.c 2012-01-07 21:01:34.552000061 +0800
> +++ next/fs/fs-writeback.c 2012-01-07 21:22:45.504000051 +0800
> @@ -20,6 +20,7 @@
> #include <linux/sched.h>
> #include <linux/fs.h>
> #include <linux/mm.h>
> +#include <linux/pagemap.h>
> #include <linux/kthread.h>
> #include <linux/freezer.h>
> #include <linux/writeback.h>
> @@ -29,6 +30,11 @@
> #include "internal.h"
>
> /*
> + * 4MB minimal write chunk size
> + */
> +#define MIN_WRITEBACK_PAGES (4096UL >> (PAGE_CACHE_SHIFT - 10))
> +
> +/*
> * Passed into wb_writeback(), essentially a subset of writeback_control
> */
> struct wb_writeback_work {
> --- next.orig/include/linux/writeback.h 2012-01-07 21:01:34.544000059 +0800
> +++ next/include/linux/writeback.h 2012-01-07 21:13:09.008000026 +0800
> @@ -25,11 +25,6 @@ DECLARE_PER_CPU(int, dirty_throttle_leak
> #define DIRTY_SCOPE 8
> #define DIRTY_FULL_SCOPE (DIRTY_SCOPE / 2)
>
> -/*
> - * 4MB minimal write chunk size
> - */
> -#define MIN_WRITEBACK_PAGES (4096UL >> (PAGE_CACHE_SHIFT - 10))
> -
> struct backing_dev_info;
>
> /*
--
~Randy
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