Re: [PATCH/RFC 4/14] Reclaim Scalability: Define page_anon() function

[mel@skynet.ie (Mel Gorman)]

On (14/09/07 16:54), Lee Schermerhorn didst pronounce:
> PATCH/RFC 03/14 Reclaim Scalability: Define page_anon() function
> 	to answer the question: is page backed by swap space?
> 
> Against:  2.6.23-rc4-mm1
> 
> Originally part of Rik van Riel's split-lru patch.  Extracted
> to make available for other, independent reclaim patches.
> 
> Moved page_anon() inline function to linux/mm_inline.h where it will
> be needed by subsequent "split LRU" and "noreclaim" patches.  
> 
> page_anon() requires the definition of struct address_space() from
> linux/fs.h.  A patch in 2.6.23-rc1-mm* removed the include of fs.h
> from linux/mm.h in favor of including it where it's needed.   Add it
> back to mm_inline.h, which is included from very few places.  These
> include all the places where page_anon() is needed--so far.
> 
> Originally posted, but not Signed-off-by:  Rik van Riel <riel@redhat.com>
> Signed-off-by:  Lee Schermerhorn <lee.schermerhorn@hp.com>
> 
>  include/linux/mm_inline.h |   29 +++++++++++++++++++++++++++++
>  mm/shmem.c                |    4 ++--
>  2 files changed, 31 insertions(+), 2 deletions(-)
> 
> Index: Linux/include/linux/mm_inline.h
> ===================================================================
> --- Linux.orig/include/linux/mm_inline.h	2007-07-08 19:32:17.000000000 -0400
> +++ Linux/include/linux/mm_inline.h	2007-09-10 11:45:22.000000000 -0400
> @@ -1,3 +1,31 @@
> +#ifndef LINUX_MM_INLINE_H
> +#define LINUX_MM_INLINE_H
> +
> +#include <linux/fs.h> 	/* need struct address_space for page_anon() */
> +
> +/*
> + * Returns true if this page is anonymous, tmpfs or otherwise swap backed.
> + */
> +extern const struct address_space_operations shmem_aops;
> +static inline int page_anon(struct page *page)
> +{
> +	struct address_space *mapping;
> +
> +	if (PageAnon(page) || PageSwapCache(page))
> +		return 1;
> +	mapping = page_mapping(page);
> +	if (!mapping || !mapping->a_ops)
> +		return 0;
> +	if (mapping->a_ops == &shmem_aops)
> +		return 1;
> +	/* Should ramfs pages go onto an mlocked list instead? */
> +	if ((unlikely(mapping->a_ops->writepage == NULL && PageDirty(page))))
> +		return 1;

Does this last check belong as part of this patch? It looks like it
should be later in the set and doesn't seem to be checking if the page
is anon or not.

Separate helper prehaps?

> +
> +	/* The page is page cache backed by a normal filesystem. */
> +	return 0;
> +}
> +
>  static inline void
>  add_page_to_active_list(struct zone *zone, struct page *page)
>  {
> @@ -38,3 +66,4 @@ del_page_from_lru(struct zone *zone, str
>  	}
>  }
>  
> +#endif
> Index: Linux/mm/shmem.c
> ===================================================================
> --- Linux.orig/mm/shmem.c	2007-09-10 10:09:47.000000000 -0400
> +++ Linux/mm/shmem.c	2007-09-10 11:45:22.000000000 -0400
> @@ -180,7 +180,7 @@ static inline void shmem_unacct_blocks(u
>  }
>  
>  static const struct super_operations shmem_ops;
> -static const struct address_space_operations shmem_aops;
> +const struct address_space_operations shmem_aops;
>  static const struct file_operations shmem_file_operations;
>  static const struct inode_operations shmem_inode_operations;
>  static const struct inode_operations shmem_dir_inode_operations;
> @@ -2353,7 +2353,7 @@ static void destroy_inodecache(void)
>  	kmem_cache_destroy(shmem_inode_cachep);
>  }
>  
> -static const struct address_space_operations shmem_aops = {
> +const struct address_space_operations shmem_aops = {
>  	.writepage	= shmem_writepage,
>  	.set_page_dirty	= __set_page_dirty_no_writeback,
>  #ifdef CONFIG_TMPFS
> 

-- 
-- 
Mel Gorman
Part-time Phd Student                          Linux Technology Center
University of Limerick                         IBM Dublin Software Lab

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