fat: convert to use the new truncate convention.

Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index ed33904..7bf45ae 100644
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -142,14 +142,29 @@
 	return mpage_readpages(mapping, pages, nr_pages, fat_get_block);
 }
 
+static void fat_write_failed(struct address_space *mapping, loff_t to)
+{
+	struct inode *inode = mapping->host;
+
+	if (to > inode->i_size) {
+		truncate_pagecache(inode, to, inode->i_size);
+		fat_truncate_blocks(inode, inode->i_size);
+	}
+}
+
 static int fat_write_begin(struct file *file, struct address_space *mapping,
 			loff_t pos, unsigned len, unsigned flags,
 			struct page **pagep, void **fsdata)
 {
+	int err;
+
 	*pagep = NULL;
-	return cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
-				fat_get_block,
+	err = cont_write_begin_newtrunc(file, mapping, pos, len, flags,
+				pagep, fsdata, fat_get_block,
 				&MSDOS_I(mapping->host)->mmu_private);
+	if (err < 0)
+		fat_write_failed(mapping, pos + len);
+	return err;
 }
 
 static int fat_write_end(struct file *file, struct address_space *mapping,
@@ -159,6 +174,8 @@
 	struct inode *inode = mapping->host;
 	int err;
 	err = generic_write_end(file, mapping, pos, len, copied, pagep, fsdata);
+	if (err < len)
+		fat_write_failed(mapping, pos + len);
 	if (!(err < 0) && !(MSDOS_I(inode)->i_attrs & ATTR_ARCH)) {
 		inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
 		MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
@@ -172,7 +189,9 @@
 			     loff_t offset, unsigned long nr_segs)
 {
 	struct file *file = iocb->ki_filp;
-	struct inode *inode = file->f_mapping->host;
+	struct address_space *mapping = file->f_mapping;
+	struct inode *inode = mapping->host;
+	ssize_t ret;
 
 	if (rw == WRITE) {
 		/*
@@ -193,8 +212,12 @@
 	 * FAT need to use the DIO_LOCKING for avoiding the race
 	 * condition of fat_get_block() and ->truncate().
 	 */
-	return blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
-				  offset, nr_segs, fat_get_block, NULL);
+	ret = blockdev_direct_IO_newtrunc(rw, iocb, inode, inode->i_sb->s_bdev,
+				iov, offset, nr_segs, fat_get_block, NULL);
+	if (ret < 0 && (rw & WRITE))
+		fat_write_failed(mapping, offset + iov_length(iov, nr_segs));
+
+	return ret;
 }
 
 static sector_t _fat_bmap(struct address_space *mapping, sector_t block)
@@ -429,7 +452,7 @@
 {
 	truncate_inode_pages(&inode->i_data, 0);
 	inode->i_size = 0;
-	fat_truncate(inode);
+	fat_truncate_blocks(inode, 0);
 	clear_inode(inode);
 }