diff --git a/fs/ubifs/crypto.c b/fs/ubifs/crypto.c
index c57b46a352d8..3125e76376ee 100644
--- a/fs/ubifs/crypto.c
+++ b/fs/ubifs/crypto.c
@@ -24,6 +24,17 @@ static bool ubifs_crypt_empty_dir(struct inode *inode)
 	return ubifs_check_dir_empty(inode) == 0;
 }
 
+/**
+ * ubifs_encrypt - Encrypt data.
+ * @inode: inode which refers to the data node
+ * @dn: data node to encrypt
+ * @in_len: length of data to be compressed
+ * @out_len: allocated memory size for the data area of @dn
+ * @block: logical block number of the block
+ *
+ * This function encrypt a possibly-compressed data in the data node.
+ * The encrypted data length will store in @out_len.
+ */
 int ubifs_encrypt(const struct inode *inode, struct ubifs_data_node *dn,
 		  unsigned int in_len, unsigned int *out_len, int block)
 {
diff --git a/fs/ubifs/journal.c b/fs/ubifs/journal.c
index 75dab0ae3939..2b1d7c4297bf 100644
--- a/fs/ubifs/journal.c
+++ b/fs/ubifs/journal.c
@@ -1472,23 +1472,25 @@ out_free:
  * @block: data block number
  * @dn: data node to re-compress
  * @new_len: new length
+ * @dn_size: size of the data node @dn in memory
  *
  * This function is used when an inode is truncated and the last data node of
  * the inode has to be re-compressed/encrypted and re-written.
  */
 static int truncate_data_node(const struct ubifs_info *c, const struct inode *inode,
 			      unsigned int block, struct ubifs_data_node *dn,
-			      int *new_len)
+			      int *new_len, int dn_size)
 {
 	void *buf;
-	int err, dlen, compr_type, out_len, old_dlen;
+	int err, dlen, compr_type, out_len, data_size;
 
 	out_len = le32_to_cpu(dn->size);
 	buf = kmalloc_array(out_len, WORST_COMPR_FACTOR, GFP_NOFS);
 	if (!buf)
 		return -ENOMEM;
 
-	dlen = old_dlen = le32_to_cpu(dn->ch.len) - UBIFS_DATA_NODE_SZ;
+	dlen = le32_to_cpu(dn->ch.len) - UBIFS_DATA_NODE_SZ;
+	data_size = dn_size - UBIFS_DATA_NODE_SZ;
 	compr_type = le16_to_cpu(dn->compr_type);
 
 	if (IS_ENCRYPTED(inode)) {
@@ -1508,11 +1510,11 @@ static int truncate_data_node(const struct ubifs_info *c, const struct inode *in
 	}
 
 	if (IS_ENCRYPTED(inode)) {
-		err = ubifs_encrypt(inode, dn, out_len, &old_dlen, block);
+		err = ubifs_encrypt(inode, dn, out_len, &data_size, block);
 		if (err)
 			goto out;
 
-		out_len = old_dlen;
+		out_len = data_size;
 	} else {
 		dn->compr_size = 0;
 	}
@@ -1550,6 +1552,7 @@ int ubifs_jnl_truncate(struct ubifs_info *c, const struct inode *inode,
 	struct ubifs_trun_node *trun;
 	struct ubifs_data_node *dn;
 	int err, dlen, len, lnum, offs, bit, sz, sync = IS_SYNC(inode);
+	int dn_size;
 	struct ubifs_inode *ui = ubifs_inode(inode);
 	ino_t inum = inode->i_ino;
 	unsigned int blk;
@@ -1562,10 +1565,13 @@ int ubifs_jnl_truncate(struct ubifs_info *c, const struct inode *inode,
 	ubifs_assert(c, S_ISREG(inode->i_mode));
 	ubifs_assert(c, mutex_is_locked(&ui->ui_mutex));
 
-	sz = UBIFS_TRUN_NODE_SZ + UBIFS_INO_NODE_SZ +
-	     UBIFS_MAX_DATA_NODE_SZ * WORST_COMPR_FACTOR;
+	dn_size = COMPRESSED_DATA_NODE_BUF_SZ;
 
-	sz += ubifs_auth_node_sz(c);
+	if (IS_ENCRYPTED(inode))
+		dn_size += UBIFS_CIPHER_BLOCK_SIZE;
+
+	sz =  UBIFS_TRUN_NODE_SZ + UBIFS_INO_NODE_SZ +
+		dn_size + ubifs_auth_node_sz(c);
 
 	ino = kmalloc(sz, GFP_NOFS);
 	if (!ino)
@@ -1596,15 +1602,15 @@ int ubifs_jnl_truncate(struct ubifs_info *c, const struct inode *inode,
 			if (dn_len <= 0 || dn_len > UBIFS_BLOCK_SIZE) {
 				ubifs_err(c, "bad data node (block %u, inode %lu)",
 					  blk, inode->i_ino);
-				ubifs_dump_node(c, dn, sz - UBIFS_INO_NODE_SZ -
-						UBIFS_TRUN_NODE_SZ);
+				ubifs_dump_node(c, dn, dn_size);
 				goto out_free;
 			}
 
 			if (dn_len <= dlen)
 				dlen = 0; /* Nothing to do */
 			else {
-				err = truncate_data_node(c, inode, blk, dn, &dlen);
+				err = truncate_data_node(c, inode, blk, dn,
+						&dlen, dn_size);
 				if (err)
 					goto out_free;
 			}