Commit 46017e95 authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
Browse files

swapin_readahead: move and rearrange args 



swapin_readahead has never sat well in mm/memory.c: move it to mm/swap_state.c
beside its kindred read_swap_cache_async.  Why were its args in a different
order?  rearrange them.  And since it was always followed by a
read_swap_cache_async of the target page, fold that in and return struct
page*.  Then CONFIG_SWAP=n no longer needs valid_swaphandles and
read_swap_cache_async stubs.

Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
Acked-by: default avatarRik van Riel <riel@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c4cc6d07

include/linux/swap.h

+7 −12
Original line number Diff line number Diff line
@@ -158,9 +158,6 @@ struct swap_list_t { 
/* Swap 50% full? Release swapcache more aggressively.. */

#define vm_swap_full() (nr_swap_pages*2 < total_swap_pages)



/* linux/mm/memory.c */

extern void swapin_readahead(swp_entry_t, unsigned long, struct vm_area_struct *);



/* linux/mm/page_alloc.c */

extern unsigned long totalram_pages;

extern unsigned long totalreserve_pages;
@@ -231,8 +228,11 @@ extern int move_from_swap_cache(struct page *, unsigned long, 
extern void free_page_and_swap_cache(struct page *);

extern void free_pages_and_swap_cache(struct page **, int);

extern struct page *lookup_swap_cache(swp_entry_t);

extern struct page * read_swap_cache_async(swp_entry_t, struct vm_area_struct *vma,

					   unsigned long addr);

extern struct page *read_swap_cache_async(swp_entry_t,

			struct vm_area_struct *vma, unsigned long addr);

extern struct page *swapin_readahead(swp_entry_t,

			struct vm_area_struct *vma, unsigned long addr);



/* linux/mm/swapfile.c */

extern long total_swap_pages;

extern unsigned int nr_swapfiles;
@@ -306,7 +306,7 @@ static inline void swap_free(swp_entry_t swp) 
{

}



static inline struct page *read_swap_cache_async(swp_entry_t swp,

static inline struct page *swapin_readahead(swp_entry_t swp,

			struct vm_area_struct *vma, unsigned long addr)

{

	return NULL;
@@ -317,11 +317,6 @@ static inline struct page *lookup_swap_cache(swp_entry_t swp) 
	return NULL;

}



static inline int valid_swaphandles(swp_entry_t entry, unsigned long *offset)

{

	return 0;

}



#define can_share_swap_page(p)			(page_mapcount(p) == 1)



static inline int move_to_swap_cache(struct page *page, swp_entry_t entry)

mm/memory.c

+1 −44
Original line number Diff line number Diff line
@@ -1980,48 +1980,6 @@ int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end) 
	return 0;

}



/**

 * swapin_readahead - swap in pages in hope we need them soon

 * @entry: swap entry of this memory

 * @addr: address to start

 * @vma: user vma this addresses belong to

 *

 * Primitive swap readahead code. We simply read an aligned block of

 * (1 << page_cluster) entries in the swap area. This method is chosen

 * because it doesn't cost us any seek time.  We also make sure to queue

 * the 'original' request together with the readahead ones...

 *

 * This has been extended to use the NUMA policies from the mm triggering

 * the readahead.

 *

 * Caller must hold down_read on the vma->vm_mm if vma is not NULL.

 */

void swapin_readahead(swp_entry_t entry, unsigned long addr,struct vm_area_struct *vma)

{

	int nr_pages;

	struct page *page;

	unsigned long offset;

	unsigned long end_offset;



	/*

	 * Get starting offset for readaround, and number of pages to read.

	 * Adjust starting address by readbehind (for NUMA interleave case)?

	 * No, it's very unlikely that swap layout would follow vma layout,

	 * more likely that neighbouring swap pages came from the same node:

	 * so use the same "addr" to choose the same node for each swap read.

	 */

	nr_pages = valid_swaphandles(entry, &offset);

	for (end_offset = offset + nr_pages; offset < end_offset; offset++) {

		/* Ok, do the async read-ahead now */

		page = read_swap_cache_async(swp_entry(swp_type(entry), offset),

						vma, addr);

		if (!page)

			break;

		page_cache_release(page);

	}

	lru_add_drain();	/* Push any new pages onto the LRU now */

}



/*

 * We enter with non-exclusive mmap_sem (to exclude vma changes,

 * but allow concurrent faults), and pte mapped but not yet locked.
@@ -2049,8 +2007,7 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, 
	page = lookup_swap_cache(entry);

	if (!page) {

		grab_swap_token(); /* Contend for token _before_ read-in */

 		swapin_readahead(entry, address, vma);

 		page = read_swap_cache_async(entry, vma, address);

		page = swapin_readahead(entry, vma, address);

		if (!page) {

			/*

			 * Back out if somebody else faulted in this pte

mm/shmem.c

+2 −4
Original line number Diff line number Diff line
@@ -1036,8 +1036,7 @@ static struct page *shmem_swapin(struct shmem_inode_info *info, 
	pvma.vm_pgoff = idx;

	pvma.vm_ops = NULL;

	pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);

	swapin_readahead(entry, 0, &pvma);

	page = read_swap_cache_async(entry, &pvma, 0);

	page = swapin_readahead(entry, &pvma, 0);

	mpol_free(pvma.vm_policy);

	return page;

}
@@ -1067,8 +1066,7 @@ static inline int shmem_parse_mpol(char *value, int *policy, 
static inline struct page *

shmem_swapin(struct shmem_inode_info *info,swp_entry_t entry,unsigned long idx)

{

	swapin_readahead(entry, 0, NULL);

	return read_swap_cache_async(entry, NULL, 0);

	return swapin_readahead(entry, NULL, 0);

}



static inline struct page *

mm/swap_state.c

+47 −0
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ 
#include <linux/mm.h>

#include <linux/kernel_stat.h>

#include <linux/swap.h>

#include <linux/swapops.h>

#include <linux/init.h>

#include <linux/pagemap.h>

#include <linux/buffer_head.h>
@@ -368,3 +369,49 @@ struct page *read_swap_cache_async(swp_entry_t entry, 
		page_cache_release(new_page);

	return found_page;

}



/**

 * swapin_readahead - swap in pages in hope we need them soon

 * @entry: swap entry of this memory

 * @vma: user vma this address belongs to

 * @addr: target address for mempolicy

 *

 * Returns the struct page for entry and addr, after queueing swapin.

 *

 * Primitive swap readahead code. We simply read an aligned block of

 * (1 << page_cluster) entries in the swap area. This method is chosen

 * because it doesn't cost us any seek time.  We also make sure to queue

 * the 'original' request together with the readahead ones...

 *

 * This has been extended to use the NUMA policies from the mm triggering

 * the readahead.

 *

 * Caller must hold down_read on the vma->vm_mm if vma is not NULL.

 */

struct page *swapin_readahead(swp_entry_t entry,

			struct vm_area_struct *vma, unsigned long addr)

{

	int nr_pages;

	struct page *page;

	unsigned long offset;

	unsigned long end_offset;



	/*

	 * Get starting offset for readaround, and number of pages to read.

	 * Adjust starting address by readbehind (for NUMA interleave case)?

	 * No, it's very unlikely that swap layout would follow vma layout,

	 * more likely that neighbouring swap pages came from the same node:

	 * so use the same "addr" to choose the same node for each swap read.

	 */

	nr_pages = valid_swaphandles(entry, &offset);

	for (end_offset = offset + nr_pages; offset < end_offset; offset++) {

		/* Ok, do the async read-ahead now */

		page = read_swap_cache_async(swp_entry(swp_type(entry), offset),

						vma, addr);

		if (!page)

			break;

		page_cache_release(page);

	}

	lru_add_drain();	/* Push any new pages onto the LRU now */

	return read_swap_cache_async(entry, vma, addr);

}

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