Eric Lee / smarc-ti-linux-kernel

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Commit cb4b86ba47bb0937b71fb825b3ed88adf7a190f0

Authored by KAMEZAWA Hiroyuki
Committed by Linus Torvalds
1 parent 6837765963
Exists in master and in 20 other branches dlt-processor-sdk-linux-03.00.00.04, newt-ti-linux-3.12.y, processor-sdk-linux-01.00.00, processor-sdk-linux-02.00.01, smarc-ti-linux-3.12.10, smarc-ti-linux-3.12.y, smarc-ti-linux-3.14.y, smarc-ti-linux-3.15.y, smarc-ti-lsk-linux-4.1.y, smarct3x-processor-sdk-04.01.00.06, smarct3x-processor-sdk-linux-02.00.01, smarct3x-processor-sdk-linux-03.00.00.04, smarct4x-800-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-04.01.00.06, smarct4x-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-linux-03.00.00.04, ti-linux-3.12.y, ti-linux-3.14.y, ti-linux-3.15.y, ti-lsk-linux-4.1.y

mm: add swap cache interface for swap reference 

In a following patch, the usage of swap cache is recorded into swap_map.
This patch is for necessary interface changes to do that.

2 interfaces:

  - swapcache_prepare()
  - swapcache_free()

are added for allocating/freeing refcnt from swap-cache to existing swap
entries.  But implementation itself is not changed under this patch.  At
adding swapcache_free(), memcg's hook code is moved under
swapcache_free().  This is better than using scattered hooks.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Acked-by: Balbir Singh <balbir@in.ibm.com>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Showing 5 changed files with 33 additions and 9 deletions Side-by-side Diff

include/linux/swap.h
Diff comments   View file @ cb4b86b
... ... @@ -282,8 +282,10 @@
282 282 extern swp_entry_t get_swap_page(void);
283 283 extern swp_entry_t get_swap_page_of_type(int);
284 284 extern int swap_duplicate(swp_entry_t);
  285 +extern int swapcache_prepare(swp_entry_t);
285 286 extern int valid_swaphandles(swp_entry_t, unsigned long *);
286 287 extern void swap_free(swp_entry_t);
  288 +extern void swapcache_free(swp_entry_t, struct page *page);
287 289 extern int free_swap_and_cache(swp_entry_t);
288 290 extern int swap_type_of(dev_t, sector_t, struct block_device **);
289 291 extern unsigned int count_swap_pages(int, int);
290 292  
... ... @@ -352,8 +354,13 @@
352 354  
353 355 #define free_swap_and_cache(swp) is_migration_entry(swp)
354 356 #define swap_duplicate(swp) is_migration_entry(swp)
  357 +#define swapcache_prepare(swp) is_migration_entry(swp)
355 358  
356 359 static inline void swap_free(swp_entry_t swp)
  360 +{
  361 +}
  362 +
  363 +static inline void swapcache_free(swp_entry_t swp, struct page *page)
357 364 {
358 365 }
359 366  
... ... @@ -1097,7 +1097,7 @@
1097 1097 shmem_swp_unmap(entry);
1098 1098 unlock:
1099 1099 spin_unlock(&info->lock);
1100   - swap_free(swap);
  1100 + swapcache_free(swap, NULL);
1101 1101 redirty:
1102 1102 set_page_dirty(page);
1103 1103 if (wbc->for_reclaim)
... ... @@ -162,11 +162,11 @@
162 162 return 1;
163 163 case -EEXIST:
164 164 /* Raced with "speculative" read_swap_cache_async */
165   - swap_free(entry);
  165 + swapcache_free(entry, NULL);
166 166 continue;
167 167 default:
168 168 /* -ENOMEM radix-tree allocation failure */
169   - swap_free(entry);
  169 + swapcache_free(entry, NULL);
170 170 return 0;
171 171 }
172 172 }
... ... @@ -188,8 +188,7 @@
188 188 __delete_from_swap_cache(page);
189 189 spin_unlock_irq(&swapper_space.tree_lock);
190 190  
191   - mem_cgroup_uncharge_swapcache(page, entry);
192   - swap_free(entry);
  191 + swapcache_free(entry, page);
193 192 page_cache_release(page);
194 193 }
195 194  
... ... @@ -293,7 +292,7 @@
293 292 /*
294 293 * Swap entry may have been freed since our caller observed it.
295 294 */
296   - if (!swap_duplicate(entry))
  295 + if (!swapcache_prepare(entry))
297 296 break;
298 297  
299 298 /*
... ... @@ -317,7 +316,7 @@
317 316 }
318 317 ClearPageSwapBacked(new_page);
319 318 __clear_page_locked(new_page);
320   - swap_free(entry);
  319 + swapcache_free(entry, NULL);
321 320 } while (err != -ENOMEM);
322 321  
323 322 if (new_page)
... ... @@ -510,6 +510,16 @@
510 510 }
511 511  
512 512 /*
  513 + * Called after dropping swapcache to decrease refcnt to swap entries.
  514 + */
  515 +void swapcache_free(swp_entry_t entry, struct page *page)
  516 +{
  517 + if (page)
  518 + mem_cgroup_uncharge_swapcache(page, entry);
  519 + return swap_free(entry);
  520 +}
  521 +
  522 +/*
513 523 * How many references to page are currently swapped out?
514 524 */
515 525 static inline int page_swapcount(struct page *page)
... ... @@ -1978,6 +1988,15 @@
1978 1988 printk(KERN_ERR "swap_dup: %s%08lx\n", Bad_file, entry.val);
1979 1989 goto out;
1980 1990 }
  1991 +
  1992 +/*
  1993 + * Called when allocating swap cache for exising swap entry,
  1994 + */
  1995 +int swapcache_prepare(swp_entry_t entry)
  1996 +{
  1997 + return swap_duplicate(entry);
  1998 +}
  1999 +
1981 2000  
1982 2001 struct swap_info_struct *
1983 2002 get_swap_info_struct(unsigned type)
... ... @@ -470,8 +470,7 @@
470 470 swp_entry_t swap = { .val = page_private(page) };
471 471 __delete_from_swap_cache(page);
472 472 spin_unlock_irq(&mapping->tree_lock);
473   - mem_cgroup_uncharge_swapcache(page, swap);
474   - swap_free(swap);
  473 + swapcache_free(swap, page);
475 474 } else {
476 475 __remove_from_page_cache(page);
477 476 spin_unlock_irq(&mapping->tree_lock);