1 files changed, 53 insertions, 9 deletions

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 7de11dcd534d..c3afd3242b54 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -54,7 +54,8 @@ static inline void mapping_set_error(struct address_space *mapping, int error)
 	__filemap_set_wb_err(mapping, error);
 
 	/* Record it in superblock */
-	errseq_set(&mapping->host->i_sb->s_wb_err, error);
+	if (mapping->host)
+		errseq_set(&mapping->host->i_sb->s_wb_err, error);
 
 	/* Record it in flags for now, for legacy callers */
 	if (error == -ENOSPC)
@@ -278,6 +279,7 @@ pgoff_t page_cache_prev_miss(struct address_space *mapping,
 #define FGP_NOFS		0x00000010
 #define FGP_NOWAIT		0x00000020
 #define FGP_FOR_MMAP		0x00000040
+#define FGP_HEAD		0x00000080
 
 struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset,
 		int fgp_flags, gfp_t cache_gfp_mask);
@@ -309,18 +311,37 @@ static inline struct page *find_get_page_flags(struct address_space *mapping,
  * @mapping: the address_space to search
  * @offset: the page index
  *
- * Looks up the page cache slot at @mapping & @offset.  If there is a
+ * Looks up the page cache entry at @mapping & @offset.  If there is a
  * page cache page, it is returned locked and with an increased
  * refcount.
  *
- * Otherwise, %NULL is returned.
- *
- * find_lock_page() may sleep.
+ * Context: May sleep.
+ * Return: A struct page or %NULL if there is no page in the cache for this
+ * index.
  */
 static inline struct page *find_lock_page(struct address_space *mapping,
-					pgoff_t offset)
+					pgoff_t index)
+{
+	return pagecache_get_page(mapping, index, FGP_LOCK, 0);
+}
+
+/**
+ * find_lock_head - Locate, pin and lock a pagecache page.
+ * @mapping: The address_space to search.
+ * @offset: The page index.
+ *
+ * Looks up the page cache entry at @mapping & @offset.  If there is a
+ * page cache page, its head page is returned locked and with an increased
+ * refcount.
+ *
+ * Context: May sleep.
+ * Return: A struct page which is !PageTail, or %NULL if there is no page
+ * in the cache for this index.
+ */
+static inline struct page *find_lock_head(struct address_space *mapping,
+					pgoff_t index)
 {
-	return pagecache_get_page(mapping, offset, FGP_LOCK, 0);
+	return pagecache_get_page(mapping, index, FGP_LOCK | FGP_HEAD, 0);
 }
 
 /**
@@ -371,6 +392,15 @@ static inline struct page *grab_cache_page_nowait(struct address_space *mapping,
 			mapping_gfp_mask(mapping));
 }
 
+/* Does this page contain this index? */
+static inline bool thp_contains(struct page *head, pgoff_t index)
+{
+	/* HugeTLBfs indexes the page cache in units of hpage_size */
+	if (PageHuge(head))
+		return head->index == index;
+	return page_index(head) == (index & ~(thp_nr_pages(head) - 1UL));
+}
+
 /*
  * Given the page we found in the page cache, return the page corresponding
  * to this index in the file
@@ -384,8 +414,6 @@ static inline struct page *find_subpage(struct page *head, pgoff_t index)
 	return head + (index & (thp_nr_pages(head) - 1));
 }
 
-struct page *find_get_entry(struct address_space *mapping, pgoff_t offset);
-struct page *find_lock_entry(struct address_space *mapping, pgoff_t offset);
 unsigned find_get_entries(struct address_space *mapping, pgoff_t start,
 			  unsigned int nr_entries, struct page **entries,
 			  pgoff_t *indices);
@@ -899,4 +927,20 @@ static inline int page_mkwrite_check_truncate(struct page *page,
 	return offset;
 }
 
+/**
+ * i_blocks_per_page - How many blocks fit in this page.
+ * @inode: The inode which contains the blocks.
+ * @page: The page (head page if the page is a THP).
+ *
+ * If the block size is larger than the size of this page, return zero.
+ *
+ * Context: The caller should hold a refcount on the page to prevent it
+ * from being split.
+ * Return: The number of filesystem blocks covered by this page.
+ */
+static inline
+unsigned int i_blocks_per_page(struct inode *inode, struct page *page)
+{
+	return thp_size(page) >> inode->i_blkbits;
+}
 #endif /* _LINUX_PAGEMAP_H */