hfsplus: Call hfsplus_write_begin() and generic_write_end() directly

There is only one kind of write_begin/write_end aops, so we don't need
to look up which aop it is, just make hfsplus_write_begin() available to
this file and call it directly.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

fs/hfsplus/extents.c

@@ -557,12 +557,12 @@ void hfsplus_file_truncate(struct inode *inode)
 		void *fsdata;
 		loff_t size = inode->i_size;
 
-		res = pagecache_write_begin(NULL, mapping, size, 0, 0,
+		res = hfsplus_write_begin(NULL, mapping, size, 0,
 					  &page, &fsdata);
 		if (res)
 			return;
-		res = pagecache_write_end(NULL, mapping, size,
-			0, 0, page, fsdata);
+		res = generic_write_end(NULL, mapping, size, 0, 0,
+					page, fsdata);
 		if (res < 0)
 			return;
 		mark_inode_dirty(inode);

fs/hfsplus/hfsplus_fs.h

@@ -468,6 +468,8 @@ extern const struct address_space_operations hfsplus_aops;
 extern const struct address_space_operations hfsplus_btree_aops;
 extern const struct dentry_operations hfsplus_dentry_operations;
 
+int hfsplus_write_begin(struct file *file, struct address_space *mapping,
+		loff_t pos, unsigned len, struct page **pagep, void **fsdata);
 struct inode *hfsplus_new_inode(struct super_block *sb, struct inode *dir,
 				umode_t mode);
 void hfsplus_delete_inode(struct inode *inode);

fs/hfsplus/inode.c

@@ -43,9 +43,8 @@ static void hfsplus_write_failed(struct address_space *mapping, loff_t to)
 	}
 }
 
-static int hfsplus_write_begin(struct file *file, struct address_space *mapping,
-			loff_t pos, unsigned len,
-			struct page **pagep, void **fsdata)
+int hfsplus_write_begin(struct file *file, struct address_space *mapping,
+		loff_t pos, unsigned len, struct page **pagep, void **fsdata)
 {
 	int ret;