diff --git a/fs/jfs/jfs_imap.c b/fs/jfs/jfs_imap.c
index 799d3837e7c2..c0cf74e7392b 100644
--- a/fs/jfs/jfs_imap.c
+++ b/fs/jfs/jfs_imap.c
@@ -1319,7 +1319,7 @@ diInitInode(struct inode *ip, int iagno, int ino, int extno, struct iag * iagp)
 int diAlloc(struct inode *pip, bool dir, struct inode *ip)
 {
 	int rc, ino, iagno, addext, extno, bitno, sword;
-	int nwords, rem, i, agno;
+	int nwords, rem, i, agno, dn_numag;
 	u32 mask, inosmap, extsmap;
 	struct inode *ipimap;
 	struct metapage *mp;
@@ -1355,6 +1355,9 @@ int diAlloc(struct inode *pip, bool dir, struct inode *ip)
 
 	/* get the ag number of this iag */
 	agno = BLKTOAG(JFS_IP(pip)->agstart, JFS_SBI(pip->i_sb));
+	dn_numag = JFS_SBI(pip->i_sb)->bmap->db_numag;
+	if (agno < 0 || agno > dn_numag)
+		return -EIO;
 
 	if (atomic_read(&JFS_SBI(pip->i_sb)->bmap->db_active[agno])) {
 		/*