path: root/mm
diff options
authorMel Gorman <mgorman@suse.de>2012-07-31 16:44:47 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-07-31 18:42:47 -0700
commitf981c5950fa85916ba49bea5d9a7a5078f47e569 (patch)
treee742598755e57e1bbed06dc90b05fe6e13091236 /mm
parent6290c2c439732727899405f39fb76c2f5585b707 (diff)
mm: methods for teaching filesystems about PG_swapcache pages
In order to teach filesystems to handle swap cache pages, three new page functions are introduced: pgoff_t page_file_index(struct page *); loff_t page_file_offset(struct page *); struct address_space *page_file_mapping(struct page *); page_file_index() - gives the offset of this page in the file in PAGE_CACHE_SIZE blocks. Like page->index is for mapped pages, this function also gives the correct index for PG_swapcache pages. page_file_offset() - uses page_file_index(), so that it will give the expected result, even for PG_swapcache pages. page_file_mapping() - gives the mapping backing the actual page; that is for swap cache pages it will give swap_file->f_mapping. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: David S. Miller <davem@davemloft.net> Cc: Eric B Munson <emunson@mgebm.net> Cc: Eric Paris <eparis@redhat.com> Cc: James Morris <jmorris@namei.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Mike Christie <michaelc@cs.wisc.edu> Cc: Neil Brown <neilb@suse.de> Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Cc: Xiaotian Feng <dfeng@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
1 files changed, 26 insertions, 0 deletions
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 71373d03fcee..f89af5ba2eb2 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -33,6 +33,7 @@
#include <linux/oom.h>
#include <linux/frontswap.h>
#include <linux/swapfile.h>
+#include <linux/export.h>
#include <asm/pgtable.h>
#include <asm/tlbflush.h>
@@ -2285,6 +2286,31 @@ int swapcache_prepare(swp_entry_t entry)
return __swap_duplicate(entry, SWAP_HAS_CACHE);
+struct swap_info_struct *page_swap_info(struct page *page)
+ swp_entry_t swap = { .val = page_private(page) };
+ BUG_ON(!PageSwapCache(page));
+ return swap_info[swp_type(swap)];
+ * out-of-line __page_file_ methods to avoid include hell.
+ */
+struct address_space *__page_file_mapping(struct page *page)
+ VM_BUG_ON(!PageSwapCache(page));
+ return page_swap_info(page)->swap_file->f_mapping;
+pgoff_t __page_file_index(struct page *page)
+ swp_entry_t swap = { .val = page_private(page) };
+ VM_BUG_ON(!PageSwapCache(page));
+ return swp_offset(swap);
* add_swap_count_continuation - called when a swap count is duplicated
* beyond SWAP_MAP_MAX, it allocates a new page and links that to the entry's