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Message-ID: <20140512012040.GH5480@thunk.org>
Date:	Sun, 11 May 2014 21:20:40 -0400
From:	Theodore Ts'o <tytso@....edu>
To:	Lukáš Czerner <lczerner@...hat.com>
Cc:	"Darrick J. Wong" <darrick.wong@...cle.com>,
	linux-ext4@...r.kernel.org
Subject: Re: [PATCH 05/37] debugfs: teach logdump to deal with 64bit revoke
 tables

The original code was a bit buggy in that it assumed "unsigned int" is
guaranteed to be 4 bytes --- which of course, is not guaranteed,
although in practice it's true for most systems.

I also tend to think that lots of extra casts are bad for readability,
and while I used to avoid constructs like this because gdb used to
choke horribly on variables defined in nested scopes, this has
thankfully been fixed for years --- even the most ancient and decrepit
RHEL system (or debian oldstable :-P) should have gdb's that can
correctly deal with this:

	if (32-bit file system) {
		__u32 *entry = ...;
		rblock = be32_to_cpu(*entry);
	} else {
		__u64 *entry = ...;
		rblock = ext2fs_be64_to_cpu(*entry);
	} 

					- Ted

commit a1ff15f83b3ab4b4f524cea48e149ec9be93908c
Author: Darrick J. Wong <darrick.wong@...cle.com>
Date:   Sun May 11 20:57:18 2014 -0400

    debugfs: teach logdump to deal with 64bit revoke tables
    
    The logdump command doesn't know how to deal with revoke tables in
    64bit journals, so teach it to do this.
    
    Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>
    Signed-off-by: Theodore Ts'o <tytso@....edu>

diff --git a/debugfs/logdump.c b/debugfs/logdump.c
index 2d0efaf..211e11a 100644
--- a/debugfs/logdump.c
+++ b/debugfs/logdump.c
@@ -526,28 +526,37 @@ static void dump_revoke_block(FILE *out_file, char *buf,
 {
 	int			offset, max;
 	journal_revoke_header_t *header;
-	unsigned int		*entry, rblock;
+	unsigned long long	rblock;
+	int			tag_size = sizeof(__u32);
 
 	if (dump_all)
 		fprintf(out_file, "Dumping revoke block, sequence %u, at "
 			"block %u:\n", transaction, blocknr);
 
+	if (be32_to_cpu(jsb->s_feature_incompat) & JFS_FEATURE_INCOMPAT_64BIT)
+		tag_size = sizeof(__u64);
+
 	header = (journal_revoke_header_t *) buf;
 	offset = sizeof(journal_revoke_header_t);
 	max = be32_to_cpu(header->r_count);
 
 	while (offset < max) {
-		entry = (unsigned int *) (buf + offset);
-		rblock = be32_to_cpu(*entry);
+		if (tag_size == sizeof(__u32)) {
+			__u32 *entry = (__u32 *) (buf + offset);
+			rblock = be32_to_cpu(*entry);
+		} else {
+			__u64 *entry = (__u64 *) (buf + offset);
+			rblock = ext2fs_be64_to_cpu(*entry);
+		}
 		if (dump_all || rblock == block_to_dump) {
-			fprintf(out_file, "  Revoke FS block %u", rblock);
+			fprintf(out_file, "  Revoke FS block %llu", rblock);
 			if (dump_all)
 				fprintf(out_file, "\n");
 			else
 				fprintf(out_file," at block %u, sequence %u\n",
 					blocknr, transaction);
 		}
-		offset += 4;
+		offset += tag_size;
 	}
 }
 
diff --git a/tests/f_jnl_64bit/expect.0 b/tests/f_jnl_64bit/expect.0
index 2007f03..5cef2d8 100644
--- a/tests/f_jnl_64bit/expect.0
+++ b/tests/f_jnl_64bit/expect.0
@@ -1,189 +1,97 @@
 Journal starts at block 67, transaction 32
 Found expected sequence 32, type 5 (revoke table) at block 67
 Dumping revoke block, sequence 32, at block 67:
-  Revoke FS block 0
   Revoke FS block 1536
-  Revoke FS block 0
   Revoke FS block 1472
-  Revoke FS block 0
   Revoke FS block 1473
-  Revoke FS block 0
   Revoke FS block 1474
-  Revoke FS block 0
   Revoke FS block 1475
-  Revoke FS block 0
   Revoke FS block 1476
-  Revoke FS block 0
   Revoke FS block 1541
-  Revoke FS block 0
   Revoke FS block 1477
-  Revoke FS block 0
   Revoke FS block 1478
-  Revoke FS block 0
   Revoke FS block 1479
-  Revoke FS block 0
   Revoke FS block 1480
-  Revoke FS block 0
   Revoke FS block 1481
-  Revoke FS block 0
   Revoke FS block 1482
-  Revoke FS block 0
   Revoke FS block 1483
-  Revoke FS block 0
   Revoke FS block 1484
-  Revoke FS block 0
   Revoke FS block 1485
-  Revoke FS block 0
   Revoke FS block 1486
-  Revoke FS block 0
   Revoke FS block 1487
-  Revoke FS block 0
   Revoke FS block 1488
-  Revoke FS block 0
   Revoke FS block 1489
-  Revoke FS block 0
   Revoke FS block 1490
-  Revoke FS block 0
   Revoke FS block 1491
-  Revoke FS block 0
   Revoke FS block 1556
-  Revoke FS block 0
   Revoke FS block 1492
-  Revoke FS block 0
   Revoke FS block 1493
-  Revoke FS block 0
   Revoke FS block 1429
-  Revoke FS block 0
   Revoke FS block 1494
-  Revoke FS block 0
   Revoke FS block 1495
-  Revoke FS block 0
   Revoke FS block 1496
-  Revoke FS block 0
   Revoke FS block 1432
-  Revoke FS block 0
   Revoke FS block 1497
-  Revoke FS block 0
   Revoke FS block 1498
-  Revoke FS block 0
   Revoke FS block 1434
-  Revoke FS block 0
   Revoke FS block 1499
-  Revoke FS block 0
   Revoke FS block 1435
-  Revoke FS block 0
   Revoke FS block 1500
-  Revoke FS block 0
   Revoke FS block 1501
-  Revoke FS block 0
   Revoke FS block 1502
-  Revoke FS block 0
   Revoke FS block 1503
-  Revoke FS block 0
   Revoke FS block 1504
-  Revoke FS block 0
   Revoke FS block 1505
-  Revoke FS block 0
   Revoke FS block 1506
-  Revoke FS block 0
   Revoke FS block 1442
-  Revoke FS block 0
   Revoke FS block 1507
-  Revoke FS block 0
   Revoke FS block 1508
-  Revoke FS block 0
   Revoke FS block 1444
-  Revoke FS block 0
   Revoke FS block 1509
-  Revoke FS block 0
   Revoke FS block 1445
-  Revoke FS block 0
   Revoke FS block 1510
-  Revoke FS block 0
   Revoke FS block 1511
-  Revoke FS block 0
   Revoke FS block 1512
-  Revoke FS block 0
   Revoke FS block 1513
-  Revoke FS block 0
   Revoke FS block 1449
-  Revoke FS block 0
   Revoke FS block 1514
-  Revoke FS block 0
   Revoke FS block 1515
-  Revoke FS block 0
   Revoke FS block 1516
-  Revoke FS block 0
   Revoke FS block 1517
-  Revoke FS block 0
   Revoke FS block 1453
-  Revoke FS block 0
   Revoke FS block 1518
-  Revoke FS block 0
   Revoke FS block 1519
-  Revoke FS block 0
   Revoke FS block 1520
-  Revoke FS block 0
   Revoke FS block 1456
-  Revoke FS block 0
   Revoke FS block 1521
-  Revoke FS block 0
   Revoke FS block 1457
-  Revoke FS block 0
   Revoke FS block 1522
-  Revoke FS block 0
   Revoke FS block 1458
-  Revoke FS block 0
   Revoke FS block 1523
-  Revoke FS block 0
   Revoke FS block 1459
-  Revoke FS block 0
   Revoke FS block 1524
-  Revoke FS block 0
   Revoke FS block 1460
-  Revoke FS block 0
   Revoke FS block 1525
-  Revoke FS block 0
   Revoke FS block 1461
-  Revoke FS block 0
   Revoke FS block 1526
-  Revoke FS block 0
   Revoke FS block 1462
-  Revoke FS block 0
   Revoke FS block 1527
-  Revoke FS block 0
   Revoke FS block 1463
-  Revoke FS block 0
   Revoke FS block 1528
-  Revoke FS block 0
   Revoke FS block 1464
-  Revoke FS block 0
   Revoke FS block 1529
-  Revoke FS block 0
   Revoke FS block 1465
-  Revoke FS block 0
   Revoke FS block 1530
-  Revoke FS block 0
   Revoke FS block 1466
-  Revoke FS block 0
   Revoke FS block 1531
-  Revoke FS block 0
   Revoke FS block 1467
-  Revoke FS block 0
   Revoke FS block 1532
-  Revoke FS block 0
   Revoke FS block 1468
-  Revoke FS block 0
   Revoke FS block 1533
-  Revoke FS block 0
   Revoke FS block 1469
-  Revoke FS block 0
   Revoke FS block 1534
-  Revoke FS block 0
   Revoke FS block 1470
-  Revoke FS block 0
   Revoke FS block 1535
-  Revoke FS block 0
   Revoke FS block 1471
 Found expected sequence 32, type 1 (descriptor block) at block 68
 Dumping descriptor block, sequence 32, at block 68:
@@ -323,163 +231,84 @@ Dumping descriptor block, sequence 32, at block 150:
 Found expected sequence 32, type 2 (commit block) at block 201
 Found expected sequence 33, type 5 (revoke table) at block 202
 Dumping revoke block, sequence 33, at block 202:
-  Revoke FS block 0
   Revoke FS block 1600
-  Revoke FS block 0
   Revoke FS block 1601
-  Revoke FS block 0
   Revoke FS block 1537
-  Revoke FS block 0
   Revoke FS block 1602
-  Revoke FS block 0
   Revoke FS block 1538
-  Revoke FS block 0
   Revoke FS block 1603
-  Revoke FS block 0
   Revoke FS block 1539
-  Revoke FS block 0
   Revoke FS block 1604
-  Revoke FS block 0
   Revoke FS block 1540
-  Revoke FS block 0
   Revoke FS block 1605
-  Revoke FS block 0
   Revoke FS block 1606
-  Revoke FS block 0
   Revoke FS block 1542
-  Revoke FS block 0
   Revoke FS block 1607
-  Revoke FS block 0
   Revoke FS block 1543
-  Revoke FS block 0
   Revoke FS block 1608
-  Revoke FS block 0
   Revoke FS block 1544
-  Revoke FS block 0
   Revoke FS block 1609
-  Revoke FS block 0
   Revoke FS block 1545
-  Revoke FS block 0
   Revoke FS block 1610
-  Revoke FS block 0
   Revoke FS block 1546
-  Revoke FS block 0
   Revoke FS block 1611
-  Revoke FS block 0
   Revoke FS block 1547
-  Revoke FS block 0
   Revoke FS block 1612
-  Revoke FS block 0
   Revoke FS block 1548
-  Revoke FS block 0
   Revoke FS block 1613
-  Revoke FS block 0
   Revoke FS block 1549
-  Revoke FS block 0
   Revoke FS block 1614
-  Revoke FS block 0
   Revoke FS block 1550
-  Revoke FS block 0
   Revoke FS block 1615
-  Revoke FS block 0
   Revoke FS block 1551
-  Revoke FS block 0
   Revoke FS block 1616
-  Revoke FS block 0
   Revoke FS block 1552
-  Revoke FS block 0
   Revoke FS block 1617
-  Revoke FS block 0
   Revoke FS block 1553
-  Revoke FS block 0
   Revoke FS block 1554
-  Revoke FS block 0
   Revoke FS block 1555
-  Revoke FS block 0
   Revoke FS block 1557
-  Revoke FS block 0
   Revoke FS block 1558
-  Revoke FS block 0
   Revoke FS block 1559
-  Revoke FS block 0
   Revoke FS block 1560
-  Revoke FS block 0
   Revoke FS block 1561
-  Revoke FS block 0
   Revoke FS block 1562
-  Revoke FS block 0
   Revoke FS block 1563
-  Revoke FS block 0
   Revoke FS block 1564
-  Revoke FS block 0
   Revoke FS block 1565
-  Revoke FS block 0
   Revoke FS block 1566
-  Revoke FS block 0
   Revoke FS block 1567
-  Revoke FS block 0
   Revoke FS block 1568
-  Revoke FS block 0
   Revoke FS block 1569
-  Revoke FS block 0
   Revoke FS block 1570
-  Revoke FS block 0
   Revoke FS block 1571
-  Revoke FS block 0
   Revoke FS block 1572
-  Revoke FS block 0
   Revoke FS block 1573
-  Revoke FS block 0
   Revoke FS block 1574
-  Revoke FS block 0
   Revoke FS block 1575
-  Revoke FS block 0
   Revoke FS block 1576
-  Revoke FS block 0
   Revoke FS block 1577
-  Revoke FS block 0
   Revoke FS block 1578
-  Revoke FS block 0
   Revoke FS block 1579
-  Revoke FS block 0
   Revoke FS block 1580
-  Revoke FS block 0
   Revoke FS block 1581
-  Revoke FS block 0
   Revoke FS block 1582
-  Revoke FS block 0
   Revoke FS block 1583
-  Revoke FS block 0
   Revoke FS block 1584
-  Revoke FS block 0
   Revoke FS block 1585
-  Revoke FS block 0
   Revoke FS block 1586
-  Revoke FS block 0
   Revoke FS block 1587
-  Revoke FS block 0
   Revoke FS block 1588
-  Revoke FS block 0
   Revoke FS block 1589
-  Revoke FS block 0
   Revoke FS block 1590
-  Revoke FS block 0
   Revoke FS block 1591
-  Revoke FS block 0
   Revoke FS block 1592
-  Revoke FS block 0
   Revoke FS block 1593
-  Revoke FS block 0
   Revoke FS block 1594
-  Revoke FS block 0
   Revoke FS block 1595
-  Revoke FS block 0
   Revoke FS block 1596
-  Revoke FS block 0
   Revoke FS block 1597
-  Revoke FS block 0
   Revoke FS block 1598
-  Revoke FS block 0
   Revoke FS block 1599
 Found expected sequence 33, type 1 (descriptor block) at block 203
 Dumping descriptor block, sequence 33, at block 203:
--
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