1 files changed, 74 insertions, 52 deletions

diff --git a/mm/filemap.c b/mm/filemap.c
index f820e60..645a080 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -33,7 +33,6 @@
 #include <linux/cpuset.h>
 #include <linux/hardirq.h> /* for BUG_ON(!in_atomic()) only */
 #include <linux/memcontrol.h>
-#include <linux/mm_inline.h> /* for page_is_file_cache() */
 #include <linux/cleancache.h>
 #include "internal.h"
 
@@ -78,7 +77,7 @@
  *  ->i_mutex			(generic_file_buffered_write)
  *    ->mmap_sem		(fault_in_pages_readable->do_page_fault)
  *
- *  inode_wb_list_lock
+ *  bdi->wb.list_lock
  *    sb_lock			(fs/fs-writeback.c)
  *    ->mapping->tree_lock	(__sync_single_inode)
  *
@@ -96,9 +95,9 @@
  *    ->zone.lru_lock		(check_pte_range->isolate_lru_page)
  *    ->private_lock		(page_remove_rmap->set_page_dirty)
  *    ->tree_lock		(page_remove_rmap->set_page_dirty)
- *    inode_wb_list_lock	(page_remove_rmap->set_page_dirty)
+ *    bdi.wb->list_lock		(page_remove_rmap->set_page_dirty)
  *    ->inode->i_lock		(page_remove_rmap->set_page_dirty)
- *    inode_wb_list_lock	(zap_pte_range->set_page_dirty)
+ *    bdi.wb->list_lock		(zap_pte_range->set_page_dirty)
  *    ->inode->i_lock		(zap_pte_range->set_page_dirty)
  *    ->private_lock		(zap_pte_range->__set_page_dirty_buffers)
  *
@@ -128,6 +127,7 @@ void __delete_from_page_cache(struct page *page)
 
 	radix_tree_delete(&mapping->page_tree, page->index);
 	page->mapping = NULL;
+	/* Leave page->index set: truncation lookup relies upon it */
 	mapping->nrpages--;
 	__dec_zone_page_state(page, NR_FILE_PAGES);
 	if (PageSwapBacked(page))
@@ -461,6 +461,7 @@ int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
 	int error;
 
 	VM_BUG_ON(!PageLocked(page));
+	VM_BUG_ON(PageSwapBacked(page));
 
 	error = mem_cgroup_cache_charge(page, current->mm,
 					gfp_mask & GFP_RECLAIM_MASK);
@@ -478,11 +479,10 @@ int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
 		if (likely(!error)) {
 			mapping->nrpages++;
 			__inc_zone_page_state(page, NR_FILE_PAGES);
-			if (PageSwapBacked(page))
-				__inc_zone_page_state(page, NR_SHMEM);
 			spin_unlock_irq(&mapping->tree_lock);
 		} else {
 			page->mapping = NULL;
+			/* Leave page->index set: truncation relies upon it */
 			spin_unlock_irq(&mapping->tree_lock);
 			mem_cgroup_uncharge_cache_page(page);
 			page_cache_release(page);
@@ -500,22 +500,9 @@ int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
 {
 	int ret;
 
-	/*
-	 * Splice_read and readahead add shmem/tmpfs pages into the page cache
-	 * before shmem_readpage has a chance to mark them as SwapBacked: they
-	 * need to go on the anon lru below, and mem_cgroup_cache_charge
-	 * (called in add_to_page_cache) needs to know where they're going too.
-	 */
-	if (mapping_cap_swap_backed(mapping))
-		SetPageSwapBacked(page);
-
 	ret = add_to_page_cache(page, mapping, offset, gfp_mask);
-	if (ret == 0) {
-		if (page_is_file_cache(page))
-			lru_cache_add_file(page);
-		else
-			lru_cache_add_anon(page);
-	}
+	if (ret == 0)
+		lru_cache_add_file(page);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(add_to_page_cache_lru);
@@ -712,9 +699,16 @@ repeat:
 		page = radix_tree_deref_slot(pagep);
 		if (unlikely(!page))
 			goto out;
-		if (radix_tree_deref_retry(page))
-			goto repeat;
-
+		if (radix_tree_exception(page)) {
+			if (radix_tree_deref_retry(page))
+				goto repeat;
+			/*
+			 * Otherwise, shmem/tmpfs must be storing a swap entry
+			 * here as an exceptional entry: so return it without
+			 * attempting to raise page count.
+			 */
+			goto out;
+		}
 		if (!page_cache_get_speculative(page))
 			goto repeat;
 
@@ -751,7 +745,7 @@ struct page *find_lock_page(struct address_space *mapping, pgoff_t offset)
 
 repeat:
 	page = find_get_page(mapping, offset);
-	if (page) {
+	if (page && !radix_tree_exception(page)) {
 		lock_page(page);
 		/* Has the page been truncated? */
 		if (unlikely(page->mapping != mapping)) {
@@ -838,7 +832,7 @@ unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
 	rcu_read_lock();
 restart:
 	nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree,
-				(void ***)pages, start, nr_pages);
+				(void ***)pages, NULL, start, nr_pages);
 	ret = 0;
 	for (i = 0; i < nr_found; i++) {
 		struct page *page;
@@ -847,13 +841,22 @@ repeat:
 		if (unlikely(!page))
 			continue;
 
-		/*
-		 * This can only trigger when the entry at index 0 moves out
-		 * of or back to the root: none yet gotten, safe to restart.
-		 */
-		if (radix_tree_deref_retry(page)) {
-			WARN_ON(start | i);
-			goto restart;
+		if (radix_tree_exception(page)) {
+			if (radix_tree_deref_retry(page)) {
+				/*
+				 * Transient condition which can only trigger
+				 * when entry at index 0 moves out of or back
+				 * to root: none yet gotten, safe to restart.
+				 */
+				WARN_ON(start | i);
+				goto restart;
+			}
+			/*
+			 * Otherwise, shmem/tmpfs must be storing a swap entry
+			 * here as an exceptional entry: so skip over it -
+			 * we only reach this from invalidate_mapping_pages().
+			 */
+			continue;
 		}
 
 		if (!page_cache_get_speculative(page))
@@ -901,7 +904,7 @@ unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
 	rcu_read_lock();
 restart:
 	nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree,
-				(void ***)pages, index, nr_pages);
+				(void ***)pages, NULL, index, nr_pages);
 	ret = 0;
 	for (i = 0; i < nr_found; i++) {
 		struct page *page;
@@ -910,12 +913,22 @@ repeat:
 		if (unlikely(!page))
 			continue;
 
-		/*
-		 * This can only trigger when the entry at index 0 moves out
-		 * of or back to the root: none yet gotten, safe to restart.
-		 */
-		if (radix_tree_deref_retry(page))
-			goto restart;
+		if (radix_tree_exception(page)) {
+			if (radix_tree_deref_retry(page)) {
+				/*
+				 * Transient condition which can only trigger
+				 * when entry at index 0 moves out of or back
+				 * to root: none yet gotten, safe to restart.
+				 */
+				goto restart;
+			}
+			/*
+			 * Otherwise, shmem/tmpfs must be storing a swap entry
+			 * here as an exceptional entry: so stop looking for
+			 * contiguous pages.
+			 */
+			break;
+		}
 
 		if (!page_cache_get_speculative(page))
 			goto repeat;
@@ -975,12 +988,21 @@ repeat:
 		if (unlikely(!page))
 			continue;
 
-		/*
-		 * This can only trigger when the entry at index 0 moves out
-		 * of or back to the root: none yet gotten, safe to restart.
-		 */
-		if (radix_tree_deref_retry(page))
-			goto restart;
+		if (radix_tree_exception(page)) {
+			if (radix_tree_deref_retry(page)) {
+				/*
+				 * Transient condition which can only trigger
+				 * when entry at index 0 moves out of or back
+				 * to root: none yet gotten, safe to restart.
+				 */
+				goto restart;
+			}
+			/*
+			 * This function is never used on a shmem/tmpfs
+			 * mapping, so a swap entry won't be found here.
+			 */
+			BUG();
+		}
 
 		if (!page_cache_get_speculative(page))
 			goto repeat;
@@ -1792,7 +1814,7 @@ EXPORT_SYMBOL(generic_file_readonly_mmap);
 
 static struct page *__read_cache_page(struct address_space *mapping,
 				pgoff_t index,
-				int (*filler)(void *,struct page*),
+				int (*filler)(void *, struct page *),
 				void *data,
 				gfp_t gfp)
 {
@@ -1823,7 +1845,7 @@ repeat:
 
 static struct page *do_read_cache_page(struct address_space *mapping,
 				pgoff_t index,
-				int (*filler)(void *,struct page*),
+				int (*filler)(void *, struct page *),
 				void *data,
 				gfp_t gfp)
 
@@ -1863,7 +1885,7 @@ out:
  * @mapping:	the page's address_space
  * @index:	the page index
  * @filler:	function to perform the read
- * @data:	destination for read data
+ * @data:	first arg to filler(data, page) function, often left as NULL
  *
  * Same as read_cache_page, but don't wait for page to become unlocked
  * after submitting it to the filler.
@@ -1875,7 +1897,7 @@ out:
  */
 struct page *read_cache_page_async(struct address_space *mapping,
 				pgoff_t index,
-				int (*filler)(void *,struct page*),
+				int (*filler)(void *, struct page *),
 				void *data)
 {
 	return do_read_cache_page(mapping, index, filler, data, mapping_gfp_mask(mapping));
@@ -1923,7 +1945,7 @@ EXPORT_SYMBOL(read_cache_page_gfp);
  * @mapping:	the page's address_space
  * @index:	the page index
  * @filler:	function to perform the read
- * @data:	destination for read data
+ * @data:	first arg to filler(data, page) function, often left as NULL
  *
  * Read into the page cache. If a page already exists, and PageUptodate() is
  * not set, try to fill the page then wait for it to become unlocked.
@@ -1932,7 +1954,7 @@ EXPORT_SYMBOL(read_cache_page_gfp);
  */
 struct page *read_cache_page(struct address_space *mapping,
 				pgoff_t index,
-				int (*filler)(void *,struct page*),
+				int (*filler)(void *, struct page *),
 				void *data)
 {
 	return wait_on_page_read(read_cache_page_async(mapping, index, filler, data));