fs: kill block_prepare_write

__block_write_begin and block_prepare_write are identical except for slightly
different calling conventions.  Convert all callers to the __block_write_begin
calling conventions and drop block_prepare_write.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/include/linux/reiserfs_fs.h b/include/linux/reiserfs_fs.h
index 91a4177..5ca47e5 100644
--- a/include/linux/reiserfs_fs.h
+++ b/include/linux/reiserfs_fs.h
@@ -2072,6 +2072,8 @@
 void i_attrs_to_sd_attrs(struct inode *inode, __u16 * sd_attrs);
 int reiserfs_setattr(struct dentry *dentry, struct iattr *attr);
 
+int __reiserfs_write_begin(struct page *page, unsigned from, unsigned len);
+
 /* namei.c */
 void set_de_name_and_namelen(struct reiserfs_dir_entry *de);
 int search_by_entry_key(struct super_block *sb, const struct cpu_key *key,