select inst_id,sid,event,p1text,p1,p2text,p2,state from gv$session_wait where p1text='file#'

INST_ID            SID              EVENT                                    P1TEXT     P1           P2TEXT         P2         STATE               
4                     236              read by other session                 file#         19           block#           2           WAITING             
4                     353              db file sequential read               file#         19           block#           2            WAITING             
4                     358              read by other session                 file#         19           block#           2            WAITING             

SELECT relative_fno, owner, segment_name, segment_type 
 FROM dba_extents 
 WHERE file_id = 19 
 AND 2 BETWEEN block_id AND block_id + blocks - 1;

SELECT s.INST_ID,
       s.sid,
       s.serial#,
       t.used_ublk,
       t.used_urec,
       rs.segment_name,
       r.rssize,
       r.status
FROM   gv$transaction t,
       gv$session s,
       gv$rollstat r,
       dba_rollback_segs rs
WHERE  s.saddr = t.ses_addr and s.INST_ID = r.INST_ID
AND    t.xidusn = r.usn
AND    rs.segment_id = t.xidusn
ORDER BY t.used_ublk DESC

INST_ID             SID      SERIAL#       USED_UBLK   USED_UREC                  SEGMENT_NAME                  RSSIZE           STATUS          
4                   358      22925          2                 8                  _SYSSMU412_50053623$           15851520         ONLINE          
4                   236      1              1                 1                  _SYSSMU413_935804165$          31580160         ONLINE