udf: Protect truncate and file type conversion with invalidate_lock

Protect truncate and file type conversion in udf_file_write_iter() with
invalidate lock. That will allow us to serialize these paths with page
faults so that the page fault can determine the file type in a racefree
way.
Signed-off-by: Jan Kara <jack@suse.cz>

fs/udf/file.c

@@ -150,7 +150,9 @@ static ssize_t udf_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB &&
 	    inode->i_sb->s_blocksize < (udf_file_entry_alloc_offset(inode) +
 				 iocb->ki_pos + iov_iter_count(from))) {
+		filemap_invalidate_lock(inode->i_mapping);
 		retval = udf_expand_file_adinicb(inode);
+		filemap_invalidate_unlock(inode->i_mapping);
 		if (retval)
 			goto out;
 	}

fs/udf/inode.c

@@ -1145,7 +1145,7 @@ struct buffer_head *udf_bread(struct inode *inode, udf_pblk_t block,
 
 int udf_setsize(struct inode *inode, loff_t newsize)
 {
-	int err;
+	int err = 0;
 	struct udf_inode_info *iinfo;
 	unsigned int bsize = i_blocksize(inode);
 
@@ -1155,6 +1155,7 @@ int udf_setsize(struct inode *inode, loff_t newsize)
 	if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
 		return -EPERM;
 
+	filemap_invalidate_lock(inode->i_mapping);
 	iinfo = UDF_I(inode);
 	if (newsize > inode->i_size) {
 		if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
@@ -1167,11 +1168,11 @@ int udf_setsize(struct inode *inode, loff_t newsize)
 			}
 			err = udf_expand_file_adinicb(inode);
 			if (err)
-				return err;
+				goto out_unlock;
 		}
 		err = udf_extend_file(inode, newsize);
 		if (err)
-			return err;
+			goto out_unlock;
 set_size:
 		truncate_setsize(inode, newsize);
 	} else {
@@ -1189,14 +1190,14 @@ int udf_setsize(struct inode *inode, loff_t newsize)
 		err = block_truncate_page(inode->i_mapping, newsize,
 					  udf_get_block);
 		if (err)
-			return err;
+			goto out_unlock;
 		truncate_setsize(inode, newsize);
 		down_write(&iinfo->i_data_sem);
 		udf_clear_extent_cache(inode);
 		err = udf_truncate_extents(inode);
 		up_write(&iinfo->i_data_sem);
 		if (err)
-			return err;
+			goto out_unlock;
 	}
 update_time:
 	inode->i_mtime = inode->i_ctime = current_time(inode);
@@ -1204,7 +1205,9 @@ int udf_setsize(struct inode *inode, loff_t newsize)
 		udf_sync_inode(inode);
 	else
 		mark_inode_dirty(inode);
-	return 0;
+out_unlock:
+	filemap_invalidate_unlock(inode->i_mapping);
+	return err;
 }
 
 /*