fs: move inode_dio_wait calls into ->setattr

Let filesystems handle waiting for direct I/O requests themselves instead
of doing it beforehand.  This means filesystem-specific locks to prevent
new dio referenes from appearing can be held.  This is important to allow
generalizing i_dio_count to non-DIO_LOCKING filesystems.

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

fs/reiserfs/inode.c

@@ -3114,6 +3114,9 @@ int reiserfs_setattr(struct dentry *dentry, struct iattr *attr)
 			error = -EFBIG;
 			goto out;
 		}
+
+		inode_dio_wait(inode);
+
 		/* fill in hole pointers in the expanding truncate case. */
 		if (attr->ia_size > inode->i_size) {
 			error = generic_cont_expand_simple(inode, attr->ia_size);