1 files changed, 82 insertions, 58 deletions

diff --git a/mm/filemap.c b/mm/filemap.c
index a8251a8..c0018f2 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -9,7 +9,7 @@
  * most "normal" filesystems (but you don't /have/ to use this:
  * the NFS filesystem used to do this differently, for example)
  */
-#include <linux/module.h>
+#include <linux/export.h>
 #include <linux/compiler.h>
 #include <linux/fs.h>
 #include <linux/uaccess.h>
@@ -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"
 
@@ -78,10 +77,7 @@
  *  ->i_mutex			(generic_file_buffered_write)
  *    ->mmap_sem		(fault_in_pages_readable->do_page_fault)
  *
- *  ->i_mutex
- *    ->i_alloc_sem             (various)
- *
- *  inode_wb_list_lock
+ *  bdi->wb.list_lock
  *    sb_lock			(fs/fs-writeback.c)
  *    ->mapping->tree_lock	(__sync_single_inode)
  *
@@ -99,9 +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)
  *
@@ -131,6 +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))
@@ -464,6 +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);
@@ -481,11 +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);
@@ -503,22 +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);
@@ -715,9 +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;
 
@@ -754,7 +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)) {
@@ -836,13 +827,14 @@ unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
 {
 	unsigned int i;
 	unsigned int ret;
-	unsigned int nr_found;
+	unsigned int nr_found, nr_skip;
 
 	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;
+	nr_skip = 0;
 	for (i = 0; i < nr_found; i++) {
 		struct page *page;
 repeat:
@@ -850,13 +842,23 @@ 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().
+			 */
+			nr_skip++;
+			continue;
 		}
 
 		if (!page_cache_get_speculative(page))
@@ -876,7 +878,7 @@ repeat:
 	 * If all entries were removed before we could secure them,
 	 * try again, because callers stop trying once 0 is returned.
 	 */
-	if (unlikely(!ret && nr_found))
+	if (unlikely(!ret && nr_found > nr_skip))
 		goto restart;
 	rcu_read_unlock();
 	return ret;
@@ -904,7 +906,7 @@ 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;
@@ -913,12 +915,22 @@ 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;
@@ -978,12 +990,21 @@ 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;
@@ -1795,7 +1816,7 @@ 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)
 {
@@ -1826,7 +1847,7 @@ 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)
 
@@ -1866,7 +1887,7 @@ 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.
@@ -1878,7 +1899,7 @@ 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));
@@ -1926,7 +1947,7 @@ 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.
@@ -1935,7 +1956,7 @@ 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));
@@ -2094,6 +2115,7 @@ void iov_iter_advance(struct iov_iter *i, size_t bytes)
 	} else {
 		const struct iovec *iov = i->iov;
 		size_t base = i->iov_offset;
+		unsigned long nr_segs = i->nr_segs;
 
 		/*
 		 * The !iov->iov_len check ensures we skip over unlikely
@@ -2109,11 +2131,13 @@ void iov_iter_advance(struct iov_iter *i, size_t bytes)
 			base += copy;
 			if (iov->iov_len == base) {
 				iov++;
+				nr_segs--;
 				base = 0;
 			}
 		}
 		i->iov = iov;
 		i->iov_offset = base;
+		i->nr_segs = nr_segs;
 	}
 }
 EXPORT_SYMBOL(iov_iter_advance);