Revert "Move xen patchset to new version's subdir."

[people/teissler/ipfire-2.x.git] / src / patches / suse-2.6.27.25 / patches.suse / SoN-27-mm-page_file_methods.patch

diff --git a/src/patches/suse-2.6.27.25/patches.suse/SoN-27-mm-page_file_methods.patch b/src/patches/suse-2.6.27.25/patches.suse/SoN-27-mm-page_file_methods.patch
new file mode 100644 (file)
index 0000000..a5696c5
--- /dev/null
+++ b/src/patches/suse-2.6.27.25/patches.suse/SoN-27-mm-page_file_methods.patch
@@ -0,0 +1,115 @@
+From: Peter Zijlstra <a.p.zijlstra@chello.nl> 
+Subject: mm: methods for teaching filesystems about PG_swapcache pages
+Patch-mainline: No
+References: FATE#303834
+
+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>
+Acked-by: Neil Brown <neilb@suse.de>
+Acked-by: Suresh Jayaraman <sjayaraman@suse.de>
+
+---
+ include/linux/mm.h      |   25 +++++++++++++++++++++++++
+ include/linux/pagemap.h |    5 +++++
+ mm/swapfile.c           |   19 +++++++++++++++++++
+ 3 files changed, 49 insertions(+)
+
+--- a/include/linux/mm.h
++++ b/include/linux/mm.h
+@@ -646,6 +646,17 @@ static inline struct address_space *page
+       return mapping;
+ }
+ 
++extern struct address_space *__page_file_mapping(struct page *);
++
++static inline
++struct address_space *page_file_mapping(struct page *page)
++{
++      if (unlikely(PageSwapCache(page)))
++              return __page_file_mapping(page);
++
++      return page->mapping;
++}
++
+ static inline int PageAnon(struct page *page)
+ {
+       return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0;
+@@ -662,6 +673,20 @@ static inline pgoff_t page_index(struct
+       return page->index;
+ }
+ 
++extern pgoff_t __page_file_index(struct page *page);
++
++/*
++ * Return the file index of the page. Regular pagecache pages use ->index
++ * whereas swapcache pages use swp_offset(->private)
++ */
++static inline pgoff_t page_file_index(struct page *page)
++{
++      if (unlikely(PageSwapCache(page)))
++              return __page_file_index(page);
++
++      return page->index;
++}
++
+ /*
+  * The atomic page->_mapcount, like _count, starts from -1:
+  * so that transitions both from it and to it can be tracked,
+--- a/include/linux/pagemap.h
++++ b/include/linux/pagemap.h
+@@ -259,6 +259,11 @@ static inline loff_t page_offset(struct
+       return ((loff_t)page->index) << PAGE_CACHE_SHIFT;
+ }
+ 
++static inline loff_t page_file_offset(struct page *page)
++{
++      return ((loff_t)page_file_index(page)) << PAGE_CACHE_SHIFT;
++}
++
+ static inline pgoff_t linear_page_index(struct vm_area_struct *vma,
+                                       unsigned long address)
+ {
+--- a/mm/swapfile.c
++++ b/mm/swapfile.c
+@@ -1856,6 +1856,25 @@ struct swap_info_struct *page_swap_info(
+ }
+ 
+ /*
++ * 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;
++}
++EXPORT_SYMBOL_GPL(__page_file_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);
++}
++EXPORT_SYMBOL_GPL(__page_file_index);
++
++/*
+  * swap_lock prevents swap_map being freed. Don't grab an extra
+  * reference on the swaphandle, it doesn't matter if it becomes unused.
+  */