From: Jérôme Glisse <jgli...@redhat.com>

This patch switch mm to lookup the page index or offset value to be
against specific mapping. The page index value only have a meaning
against a mapping.

Using coccinelle:
---------------------------------------------------------------------
@@
struct page *P;
expression E;
@@
-P->index = E
+page_set_index(P, E)

@@
struct page *P;
@@
-P->index
+page_index(P)

@@
struct page *P;
@@
-page_index(P) << PAGE_SHIFT
+page_offset(P)

@@
expression E;
@@
-page_index(E)
+_page_index(E, mapping)

@@
expression E1, E2;
@@
-page_set_index(E1, E2)
+_page_set_index(E1, mapping, E2)

@@
expression E;
@@
-page_to_index(E)
+_page_to_index(E, mapping)

@@
expression E;
@@
-page_to_pgoff(E)
+_page_to_pgoff(E, mapping)

@@
expression E;
@@
-page_offset(E)
+_page_offset(E, mapping)

@@
expression E;
@@
-page_file_offset(E)
+_page_file_offset(E, mapping)
---------------------------------------------------------------------

Signed-off-by: Jérôme Glisse <jgli...@redhat.com>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Mel Gorman <mgor...@techsingularity.net>
Cc: linux...@kvack.org
Cc: Alexander Viro <v...@zeniv.linux.org.uk>
Cc: linux-fsde...@vger.kernel.org
---
 mm/filemap.c        | 26 ++++++++++++++------------
 mm/page-writeback.c | 16 +++++++++-------
 mm/shmem.c          | 11 +++++++----
 mm/truncate.c       | 11 ++++++-----
 4 files changed, 36 insertions(+), 28 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 012a53964215..a41c7cfb6351 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -118,7 +118,8 @@ static int page_cache_tree_insert(struct address_space 
*mapping,
        void **slot;
        int error;
 
-       error = __radix_tree_create(&mapping->page_tree, page->index, 0,
+       error = __radix_tree_create(&mapping->page_tree,
+                                   _page_index(page, mapping), 0,
                                    &node, &slot);
        if (error)
                return error;
@@ -155,7 +156,8 @@ static void page_cache_tree_delete(struct address_space 
*mapping,
                struct radix_tree_node *node;
                void **slot;
 
-               __radix_tree_lookup(&mapping->page_tree, page->index + i,
+               __radix_tree_lookup(&mapping->page_tree,
+                                   _page_index(page, mapping) + i,
                                    &node, &slot);
 
                VM_BUG_ON_PAGE(!node && nr != 1, page);
@@ -791,12 +793,12 @@ int replace_page_cache_page(struct page *old, struct page 
*new, gfp_t gfp_mask)
                void (*freepage)(struct page *);
                unsigned long flags;
 
-               pgoff_t offset = old->index;
+               pgoff_t offset = _page_index(old, mapping);
                freepage = mapping->a_ops->freepage;
 
                get_page(new);
                new->mapping = mapping;
-               new->index = offset;
+               _page_set_index(new, mapping, offset);
 
                spin_lock_irqsave(&mapping->tree_lock, flags);
                __delete_from_page_cache(old, NULL);
@@ -850,7 +852,7 @@ static int __add_to_page_cache_locked(struct page *page,
 
        get_page(page);
        page->mapping = mapping;
-       page->index = offset;
+       _page_set_index(page, mapping, offset);
 
        spin_lock_irq(&mapping->tree_lock);
        error = page_cache_tree_insert(mapping, page, shadowp);
@@ -1500,7 +1502,7 @@ struct page *find_lock_entry(struct address_space 
*mapping, pgoff_t offset)
                        put_page(page);
                        goto repeat;
                }
-               VM_BUG_ON_PAGE(page_to_pgoff(page) != offset, page);
+               VM_BUG_ON_PAGE(_page_to_pgoff(page, mapping) != offset, page);
        }
        return page;
 }
@@ -1559,7 +1561,7 @@ struct page *pagecache_get_page(struct address_space 
*mapping, pgoff_t offset,
                        put_page(page);
                        goto repeat;
                }
-               VM_BUG_ON_PAGE(page->index != offset, page);
+               VM_BUG_ON_PAGE(_page_index(page, mapping) != offset, page);
        }
 
        if (page && (fgp_flags & FGP_ACCESSED))
@@ -1751,7 +1753,7 @@ unsigned find_get_pages_range(struct address_space 
*mapping, pgoff_t *start,
 
                pages[ret] = page;
                if (++ret == nr_pages) {
-                       *start = pages[ret - 1]->index + 1;
+                       *start = _page_index(pages[ret - 1], mapping) + 1;
                        goto out;
                }
        }
@@ -1837,7 +1839,7 @@ unsigned find_get_pages_contig(struct address_space 
*mapping, pgoff_t index,
                 * otherwise we can get both false positives and false
                 * negatives, which is just confusing to the caller.
                 */
-               if (page->mapping == NULL || page_to_pgoff(page) != iter.index) 
{
+               if (page->mapping == NULL || _page_to_pgoff(page, mapping) != 
iter.index) {
                        put_page(page);
                        break;
                }
@@ -1923,7 +1925,7 @@ unsigned find_get_pages_range_tag(struct address_space 
*mapping, pgoff_t *index,
 
                pages[ret] = page;
                if (++ret == nr_pages) {
-                       *index = pages[ret - 1]->index + 1;
+                       *index = _page_index(pages[ret - 1], mapping) + 1;
                        goto out;
                }
        }
@@ -2540,7 +2542,7 @@ int filemap_fault(struct vm_fault *vmf)
                put_page(page);
                goto retry_find;
        }
-       VM_BUG_ON_PAGE(page->index != offset, page);
+       VM_BUG_ON_PAGE(_page_index(page, mapping) != offset, page);
 
        /*
         * We have a locked page in the page cache, now we need to check
@@ -2667,7 +2669,7 @@ void filemap_map_pages(struct vm_fault *vmf,
                        goto unlock;
 
                max_idx = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE);
-               if (page->index >= max_idx)
+               if (_page_index(page, mapping) >= max_idx)
                        goto unlock;
 
                if (file->f_ra.mmap_miss > 0)
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 3c14d44639c8..ed9424f84715 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2201,7 +2201,7 @@ int write_cache_pages(struct address_space *mapping,
                for (i = 0; i < nr_pages; i++) {
                        struct page *page = pvec.pages[i];
 
-                       done_index = page->index;
+                       done_index = _page_index(page, mapping);
 
                        lock_page(page);
 
@@ -2251,7 +2251,8 @@ int write_cache_pages(struct address_space *mapping,
                                         * not be suitable for data integrity
                                         * writeout).
                                         */
-                                       done_index = page->index + 1;
+                                       done_index = _page_index(page,
+                                                                mapping) + 1;
                                        done = 1;
                                        break;
                                }
@@ -2470,7 +2471,8 @@ int __set_page_dirty_nobuffers(struct page *page)
                BUG_ON(page_mapping(page) != mapping);
                WARN_ON_ONCE(!PagePrivate(page) && !PageUptodate(page));
                account_page_dirtied(page, mapping);
-               radix_tree_tag_set(&mapping->page_tree, page_index(page),
+               radix_tree_tag_set(&mapping->page_tree,
+                                  _page_index(page, mapping),
                                   PAGECACHE_TAG_DIRTY);
                spin_unlock_irqrestore(&mapping->tree_lock, flags);
                unlock_page_memcg(page);
@@ -2732,7 +2734,7 @@ int test_clear_page_writeback(struct page *page)
                ret = TestClearPageWriteback(page);
                if (ret) {
                        radix_tree_tag_clear(&mapping->page_tree,
-                                               page_index(page),
+                                               _page_index(page, mapping),
                                                PAGECACHE_TAG_WRITEBACK);
                        if (bdi_cap_account_writeback(bdi)) {
                                struct bdi_writeback *wb = inode_to_wb(inode);
@@ -2785,7 +2787,7 @@ int __test_set_page_writeback(struct page *page, bool 
keep_write)
                                                   PAGECACHE_TAG_WRITEBACK);
 
                        radix_tree_tag_set(&mapping->page_tree,
-                                               page_index(page),
+                                               _page_index(page, mapping),
                                                PAGECACHE_TAG_WRITEBACK);
                        if (bdi_cap_account_writeback(bdi))
                                inc_wb_stat(inode_to_wb(inode), WB_WRITEBACK);
@@ -2800,11 +2802,11 @@ int __test_set_page_writeback(struct page *page, bool 
keep_write)
                }
                if (!PageDirty(page))
                        radix_tree_tag_clear(&mapping->page_tree,
-                                               page_index(page),
+                                               _page_index(page, mapping),
                                                PAGECACHE_TAG_DIRTY);
                if (!keep_write)
                        radix_tree_tag_clear(&mapping->page_tree,
-                                               page_index(page),
+                                               _page_index(page, mapping),
                                                PAGECACHE_TAG_TOWRITE);
                spin_unlock_irqrestore(&mapping->tree_lock, flags);
        } else {
diff --git a/mm/shmem.c b/mm/shmem.c
index 7fee65df10b4..7f3168d547c8 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -588,7 +588,7 @@ static int shmem_add_to_page_cache(struct page *page,
 
        page_ref_add(page, nr);
        page->mapping = mapping;
-       page->index = index;
+       _page_set_index(page, mapping, index);
 
        spin_lock_irq(&mapping->tree_lock);
        if (PageTransHuge(page)) {
@@ -644,7 +644,9 @@ static void shmem_delete_from_page_cache(struct page *page, 
void *radswap)
        VM_BUG_ON_PAGE(PageCompound(page), page);
 
        spin_lock_irq(&mapping->tree_lock);
-       error = shmem_radix_tree_replace(mapping, page->index, page, radswap);
+       error = shmem_radix_tree_replace(mapping, _page_index(page, mapping),
+                                        page,
+                                        radswap);
        page->mapping = NULL;
        mapping->nrpages--;
        __dec_node_page_state(page, NR_FILE_PAGES);
@@ -822,7 +824,8 @@ static void shmem_undo_range(struct inode *inode, loff_t 
lstart, loff_t lend,
                                continue;
                        }
 
-                       VM_BUG_ON_PAGE(page_to_pgoff(page) != index, page);
+                       VM_BUG_ON_PAGE(_page_to_pgoff(page, mapping) != index,
+                                      page);
 
                        if (!trylock_page(page))
                                continue;
@@ -1267,7 +1270,7 @@ static int shmem_writepage(struct address_space 
*_mapping, struct page *page,
        VM_BUG_ON_PAGE(PageCompound(page), page);
        BUG_ON(!PageLocked(page));
        mapping = page->mapping;
-       index = page->index;
+       index = _page_index(page, mapping);
        inode = mapping->host;
        info = SHMEM_I(inode);
        if (info->flags & VM_LOCKED)
diff --git a/mm/truncate.c b/mm/truncate.c
index a9415c96c966..57d4d0948f40 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -181,7 +181,8 @@ truncate_cleanup_page(struct address_space *mapping, struct 
page *page)
 {
        if (page_mapped(page)) {
                pgoff_t nr = PageTransHuge(page) ? HPAGE_PMD_NR : 1;
-               unmap_mapping_pages(mapping, page->index, nr, false);
+               unmap_mapping_pages(mapping, _page_index(page, mapping), nr,
+                                   false);
        }
 
        if (page_has_private(page))
@@ -353,7 +354,7 @@ void truncate_inode_pages_range(struct address_space 
*mapping,
 
                        if (!trylock_page(page))
                                continue;
-                       WARN_ON(page_to_index(page) != index);
+                       WARN_ON(_page_to_index(page, mapping) != index);
                        if (PageWriteback(page)) {
                                unlock_page(page);
                                continue;
@@ -447,7 +448,7 @@ void truncate_inode_pages_range(struct address_space 
*mapping,
                                continue;
 
                        lock_page(page);
-                       WARN_ON(page_to_index(page) != index);
+                       WARN_ON(_page_to_index(page, mapping) != index);
                        wait_on_page_writeback(page);
                        truncate_inode_page(mapping, page);
                        unlock_page(page);
@@ -571,7 +572,7 @@ unsigned long invalidate_mapping_pages(struct address_space 
*mapping,
                        if (!trylock_page(page))
                                continue;
 
-                       WARN_ON(page_to_index(page) != index);
+                       WARN_ON(_page_to_index(page, mapping) != index);
 
                        /* Middle of THP: skip */
                        if (PageTransTail(page)) {
@@ -701,7 +702,7 @@ int invalidate_inode_pages2_range(struct address_space 
*mapping,
                        }
 
                        lock_page(page);
-                       WARN_ON(page_to_index(page) != index);
+                       WARN_ON(_page_to_index(page, mapping) != index);
                        if (page_is_truncated(page, mapping)) {
                                unlock_page(page);
                                continue;
-- 
2.14.3

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