JFS: Fix accounting of active allocation groups

jfs_destroy_inode was assuming that active_ag should never be set coming into
this routine.  Since it's possible for file to be extended after the file
descriptor has been closed, we need to allow the possibility.  (Dirty pages
of memory mapped files can be written after the file has been closed.)

fs/jfs/super.c

@@ -97,6 +97,11 @@ static void jfs_destroy_inode(struct inode *inode)
 {
 	struct jfs_inode_info *ji = JFS_IP(inode);
 
+	if (ji->active_ag != -1) {
+		struct bmap *bmap = JFS_SBI(inode->i_sb)->bmap;
+		atomic_dec(&bmap->db_active[ji->active_ag]);
+	}
+
 #ifdef CONFIG_JFS_POSIX_ACL
 	if (ji->i_acl && (ji->i_acl != JFS_ACL_NOT_CACHED))
 		posix_acl_release(ji->i_acl);