get rid of block_write_begin_newtrunc

Move the call to vmtruncate to get rid of accessive blocks to the callers
in preparation of the new truncate sequence and rename the non-truncating
version to block_write_begin.

While we're at it also remove several unused arguments to block_write_begin.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/ext2/inode.c

diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index 2f4dfbc..74dfe5f 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -772,9 +772,8 @@
 {
 	int ret;
 
-	*pagep = NULL;
-	ret = block_write_begin_newtrunc(file, mapping, pos, len, flags,
-					 pagep, fsdata, ext2_get_block);
+	ret = block_write_begin(mapping, pos, len, flags, pagep,
+				ext2_get_block);
 	if (ret < 0)
 		ext2_write_failed(mapping, pos + len);
 	return ret;