ntfs3: Call ntfs_write_begin() and ntfs_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 ntfs_write_begin() and ntfs_write_end()
available to this file and call them directly.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Namjae Jeon <linkinjeon@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

fs/ntfs3/file.c

@@ -157,15 +157,14 @@ static int ntfs_extend_initialized_size(struct file *file,
 		if (pos + len > new_valid)
 			len = new_valid - pos;
 
-		err = pagecache_write_begin(file, mapping, pos, len, 0, &page,
-					    &fsdata);
+		err = ntfs_write_begin(file, mapping, pos, len, &page, &fsdata);
 		if (err)
 			goto out;
 
 		zero_user_segment(page, zerofrom, PAGE_SIZE);
 
 		/* This function in any case puts page. */
-		err = pagecache_write_end(file, mapping, pos, len, len, page,
+		err = ntfs_write_end(file, mapping, pos, len, len, page,
 					  fsdata);
 		if (err < 0)
 			goto out;

fs/ntfs3/inode.c

@@ -861,9 +861,8 @@ static int ntfs_get_block_write_begin(struct inode *inode, sector_t vbn,
 				  bh_result, create, GET_BLOCK_WRITE_BEGIN);
 }
 
-static int ntfs_write_begin(struct file *file, struct address_space *mapping,
-			    loff_t pos, u32 len, struct page **pagep,
-			    void **fsdata)
+int ntfs_write_begin(struct file *file, struct address_space *mapping,
+		     loff_t pos, u32 len, struct page **pagep, void **fsdata)
 {
 	int err;
 	struct inode *inode = mapping->host;
@@ -904,10 +903,9 @@ static int ntfs_write_begin(struct file *file, struct address_space *mapping,
 /*
  * ntfs_write_end - Address_space_operations::write_end.
  */
-static int ntfs_write_end(struct file *file, struct address_space *mapping,
+int ntfs_write_end(struct file *file, struct address_space *mapping,
 		   loff_t pos, u32 len, u32 copied, struct page *page,
 		   void *fsdata)
-
 {
 	struct inode *inode = mapping->host;
 	struct ntfs_inode *ni = ntfs_i(inode);

fs/ntfs3/ntfs_fs.h

@@ -689,6 +689,11 @@ int ntfs_set_size(struct inode *inode, u64 new_size);
 int reset_log_file(struct inode *inode);
 int ntfs_get_block(struct inode *inode, sector_t vbn,
 		   struct buffer_head *bh_result, int create);
+int ntfs_write_begin(struct file *file, struct address_space *mapping,
+		     loff_t pos, u32 len, struct page **pagep, void **fsdata);
+int ntfs_write_end(struct file *file, struct address_space *mapping,
+		   loff_t pos, u32 len, u32 copied, struct page *page,
+		   void *fsdata);
 int ntfs3_write_inode(struct inode *inode, struct writeback_control *wbc);
 int ntfs_sync_inode(struct inode *inode);
 int ntfs_flush_inodes(struct super_block *sb, struct inode *i1,