summaryrefslogtreecommitdiff
path: root/drivers/md/dm-zoned-metadata.c
blob: 969954915566f2cf1a15b684eb5b3d33dca58160 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
/*
 * Copyright (C) 2017 Western Digital Corporation or its affiliates.
 *
 * This file is released under the GPL.
 */

#include "dm-zoned.h"

#include <linux/module.h>
#include <linux/crc32.h>

#define	DM_MSG_PREFIX		"zoned metadata"

/*
 * Metadata version.
 */
#define DMZ_META_VER	1

/*
 * On-disk super block magic.
 */
#define DMZ_MAGIC	((((unsigned int)('D')) << 24) | \
			 (((unsigned int)('Z')) << 16) | \
			 (((unsigned int)('B')) <<  8) | \
			 ((unsigned int)('D')))

/*
 * On disk super block.
 * This uses only 512 B but uses on disk a full 4KB block. This block is
 * followed on disk by the mapping table of chunks to zones and the bitmap
 * blocks indicating zone block validity.
 * The overall resulting metadata format is:
 *    (1) Super block (1 block)
 *    (2) Chunk mapping table (nr_map_blocks)
 *    (3) Bitmap blocks (nr_bitmap_blocks)
 * All metadata blocks are stored in conventional zones, starting from the
 * the first conventional zone found on disk.
 */
struct dmz_super {
	/* Magic number */
	__le32		magic;			/*   4 */

	/* Metadata version number */
	__le32		version;		/*   8 */

	/* Generation number */
	__le64		gen;			/*  16 */

	/* This block number */
	__le64		sb_block;		/*  24 */

	/* The number of metadata blocks, including this super block */
	__le32		nr_meta_blocks;		/*  28 */

	/* The number of sequential zones reserved for reclaim */
	__le32		nr_reserved_seq;	/*  32 */

	/* The number of entries in the mapping table */
	__le32		nr_chunks;		/*  36 */

	/* The number of blocks used for the chunk mapping table */
	__le32		nr_map_blocks;		/*  40 */

	/* The number of blocks used for the block bitmaps */
	__le32		nr_bitmap_blocks;	/*  44 */

	/* Checksum */
	__le32		crc;			/*  48 */

	/* Padding to full 512B sector */
	u8		reserved[464];		/* 512 */
};

/*
 * Chunk mapping entry: entries are indexed by chunk number
 * and give the zone ID (dzone_id) mapping the chunk on disk.
 * This zone may be sequential or random. If it is a sequential
 * zone, a second zone (bzone_id) used as a write buffer may
 * also be specified. This second zone will always be a randomly
 * writeable zone.
 */
struct dmz_map {
	__le32			dzone_id;
	__le32			bzone_id;
};

/*
 * Chunk mapping table metadata: 512 8-bytes entries per 4KB block.
 */
#define DMZ_MAP_ENTRIES		(DMZ_BLOCK_SIZE / sizeof(struct dmz_map))
#define DMZ_MAP_ENTRIES_SHIFT	(ilog2(DMZ_MAP_ENTRIES))
#define DMZ_MAP_ENTRIES_MASK	(DMZ_MAP_ENTRIES - 1)
#define DMZ_MAP_UNMAPPED	UINT_MAX

/*
 * Meta data block descriptor (for cached metadata blocks).
 */
struct dmz_mblock {
	struct rb_node		node;
	struct list_head	link;
	sector_t		no;
	atomic_t		ref;
	unsigned long		state;
	struct page		*page;
	void			*data;
};

/*
 * Metadata block state flags.
 */
enum {
	DMZ_META_DIRTY,
	DMZ_META_READING,
	DMZ_META_WRITING,
	DMZ_META_ERROR,
};

/*
 * Super block information (one per metadata set).
 */
struct dmz_sb {
	sector_t		block;
	struct dmz_mblock	*mblk;
	struct dmz_super	*sb;
};

/*
 * In-memory metadata.
 */
struct dmz_metadata {
	struct dmz_dev		*dev;

	sector_t		zone_bitmap_size;
	unsigned int		zone_nr_bitmap_blocks;

	unsigned int		nr_bitmap_blocks;
	unsigned int		nr_map_blocks;

	unsigned int		nr_useable_zones;
	unsigned int		nr_meta_blocks;
	unsigned int		nr_meta_zones;
	unsigned int		nr_data_zones;
	unsigned int		nr_rnd_zones;
	unsigned int		nr_reserved_seq;
	unsigned int		nr_chunks;

	/* Zone information array */
	struct dm_zone		*zones;

	struct dm_zone		*sb_zone;
	struct dmz_sb		sb[2];
	unsigned int		mblk_primary;
	u64			sb_gen;
	unsigned int		min_nr_mblks;
	unsigned int		max_nr_mblks;
	atomic_t		nr_mblks;
	struct rw_semaphore	mblk_sem;
	struct mutex		mblk_flush_lock;
	spinlock_t		mblk_lock;
	struct rb_root		mblk_rbtree;
	struct list_head	mblk_lru_list;
	struct list_head	mblk_dirty_list;
	struct shrinker		mblk_shrinker;

	/* Zone allocation management */
	struct mutex		map_lock;
	struct dmz_mblock	**map_mblk;
	unsigned int		nr_rnd;
	atomic_t		unmap_nr_rnd;
	struct list_head	unmap_rnd_list;
	struct list_head	map_rnd_list;

	unsigned int		nr_seq;
	atomic_t		unmap_nr_seq;
	struct list_head	unmap_seq_list;
	struct list_head	map_seq_list;

	atomic_t		nr_reserved_seq_zones;
	struct list_head	reserved_seq_zones_list;

	wait_queue_head_t	free_wq;
};

/*
 * Various accessors
 */
unsigned int dmz_id(struct dmz_metadata *zmd, struct dm_zone *zone)
{
	return ((unsigned int)(zone - zmd->zones));
}

sector_t dmz_start_sect(struct dmz_metadata *zmd, struct dm_zone *zone)
{
	return (sector_t)dmz_id(zmd, zone) << zmd->dev->zone_nr_sectors_shift;
}

sector_t dmz_start_block(struct dmz_metadata *zmd, struct dm_zone *zone)
{
	return (sector_t)dmz_id(zmd, zone) << zmd->dev->zone_nr_blocks_shift;
}

unsigned int dmz_nr_chunks(struct dmz_metadata *zmd)
{
	return zmd->nr_chunks;
}

unsigned int dmz_nr_rnd_zones(struct dmz_metadata *zmd)
{
	return zmd->nr_rnd;
}

unsigned int dmz_nr_unmap_rnd_zones(struct dmz_metadata *zmd)
{
	return atomic_read(&zmd->unmap_nr_rnd);
}

/*
 * Lock/unlock mapping table.
 * The map lock also protects all the zone lists.
 */
void dmz_lock_map(struct dmz_metadata *zmd)
{
	mutex_lock(&zmd->map_lock);
}

void dmz_unlock_map(struct dmz_metadata *zmd)
{
	mutex_unlock(&zmd->map_lock);
}

/*
 * Lock/unlock metadata access. This is a "read" lock on a semaphore
 * that prevents metadata flush from running while metadata are being
 * modified. The actual metadata write mutual exclusion is achieved with
 * the map lock and zone styate management (active and reclaim state are
 * mutually exclusive).
 */
void dmz_lock_metadata(struct dmz_metadata *zmd)
{
	down_read(&zmd->mblk_sem);
}

void dmz_unlock_metadata(struct dmz_metadata *zmd)
{
	up_read(&zmd->mblk_sem);
}

/*
 * Lock/unlock flush: prevent concurrent executions
 * of dmz_flush_metadata as well as metadata modification in reclaim
 * while flush is being executed.
 */
void dmz_lock_flush(struct dmz_metadata *zmd)
{
	mutex_lock(&zmd->mblk_flush_lock);
}

void dmz_unlock_flush(struct dmz_metadata *zmd)
{
	mutex_unlock(&zmd->mblk_flush_lock);
}

/*
 * Allocate a metadata block.
 */
static struct dmz_mblock *dmz_alloc_mblock(struct dmz_metadata *zmd,
					   sector_t mblk_no)
{
	struct dmz_mblock *mblk = NULL;

	/* See if we can reuse cached blocks */
	if (zmd->max_nr_mblks && atomic_read(&zmd->nr_mblks) > zmd->max_nr_mblks) {
		spin_lock(&zmd->mblk_lock);
		mblk = list_first_entry_or_null(&zmd->mblk_lru_list,
						struct dmz_mblock, link);
		if (mblk) {
			list_del_init(&mblk->link);
			rb_erase(&mblk->node, &zmd->mblk_rbtree);
			mblk->no = mblk_no;
		}
		spin_unlock(&zmd->mblk_lock);
		if (mblk)
			return mblk;
	}

	/* Allocate a new block */
	mblk = kmalloc(sizeof(struct dmz_mblock), GFP_NOIO);
	if (!mblk)
		return NULL;

	mblk->page = alloc_page(GFP_NOIO);
	if (!mblk->page) {
		kfree(mblk);
		return NULL;
	}

	RB_CLEAR_NODE(&mblk->node);
	INIT_LIST_HEAD(&mblk->link);
	atomic_set(&mblk->ref, 0);
	mblk->state = 0;
	mblk->no = mblk_no;
	mblk->data = page_address(mblk->page);

	atomic_inc(&zmd->nr_mblks);

	return mblk;
}

/*
 * Free a metadata block.
 */
static void dmz_free_mblock(struct dmz_metadata *zmd, struct dmz_mblock *mblk)
{
	__free_pages(mblk->page, 0);
	kfree(mblk);

	atomic_dec(&zmd->nr_mblks);
}

/*
 * Insert a metadata block in the rbtree.
 */
static void dmz_insert_mblock(struct dmz_metadata *zmd, struct dmz_mblock *mblk)
{
	struct rb_root *root = &zmd->mblk_rbtree;
	struct rb_node **new = &(root->rb_node), *parent = NULL;
	struct dmz_mblock *b;

	/* Figure out where to put the new node */
	while (*new) {
		b = container_of(*new, struct dmz_mblock, node);
		parent = *new;
		new = (b->no < mblk->no) ? &((*new)->rb_left) : &((*new)->rb_right);
	}

	/* Add new node and rebalance tree */
	rb_link_node(&mblk->node, parent, new);
	rb_insert_color(&mblk->node, root);
}

/*
 * Lookup a metadata block in the rbtree.
 */
static struct dmz_mblock *dmz_lookup_mblock(struct dmz_metadata *zmd,
					    sector_t mblk_no)
{
	struct rb_root *root = &zmd->mblk_rbtree;
	struct rb_node *node = root->rb_node;
	struct dmz_mblock *mblk;

	while (node) {
		mblk = container_of(node, struct dmz_mblock, node);
		if (mblk->no == mblk_no)
			return mblk;
		node = (mblk->no < mblk_no) ? node->rb_left : node->rb_right;
	}

	return NULL;
}

/*
 * Metadata block BIO end callback.
 */
static void dmz_mblock_bio_end_io(struct bio *bio)
{
	struct dmz_mblock *mblk = bio->bi_private;
	int flag;

	if (bio->bi_status)
		set_bit(DMZ_META_ERROR, &mblk->state);

	if (bio_op(bio) == REQ_OP_WRITE)
		flag = DMZ_META_WRITING;
	else
		flag = DMZ_META_READING;

	clear_bit_unlock(flag, &mblk->state);
	smp_mb__after_atomic();
	wake_up_bit(&mblk->state, flag);

	bio_put(bio);
}

/*
 * Read a metadata block from disk.
 */
static struct dmz_mblock *dmz_fetch_mblock(struct dmz_metadata *zmd,
					   sector_t mblk_no)
{
	struct dmz_mblock *mblk;
	sector_t block = zmd->sb[zmd->mblk_primary].block + mblk_no;
	struct bio *bio;

	/* Get block and insert it */
	mblk = dmz_alloc_mblock(zmd, mblk_no);
	if (!mblk)
		return NULL;

	spin_lock(&zmd->mblk_lock);
	atomic_inc(&mblk->ref);
	set_bit(DMZ_META_READING, &mblk->state);
	dmz_insert_mblock(zmd, mblk);
	spin_unlock(&zmd->mblk_lock);

	bio = bio_alloc(GFP_NOIO, 1);
	if (!bio) {
		dmz_free_mblock(zmd, mblk);
		return NULL;
	}

	bio->bi_iter.bi_sector = dmz_blk2sect(block);
	bio_set_dev(bio, zmd->dev->bdev);
	bio->bi_private = mblk;
	bio->bi_end_io = dmz_mblock_bio_end_io;
	bio_set_op_attrs(bio, REQ_OP_READ, REQ_META | REQ_PRIO);
	bio_add_page(bio, mblk->page, DMZ_BLOCK_SIZE, 0);
	submit_bio(bio);

	return mblk;
}

/*
 * Free metadata blocks.
 */
static unsigned long dmz_shrink_mblock_cache(struct dmz_metadata *zmd,
					     unsigned long limit)
{
	struct dmz_mblock *mblk;
	unsigned long count = 0;

	if (!zmd->max_nr_mblks)
		return 0;

	while (!list_empty(&zmd->mblk_lru_list) &&
	       atomic_read(&zmd->nr_mblks) > zmd->min_nr_mblks &&
	       count < limit) {
		mblk = list_first_entry(&zmd->mblk_lru_list,
					struct dmz_mblock, link);
		list_del_init(&mblk->link);
		rb_erase(&mblk->node, &zmd->mblk_rbtree);
		dmz_free_mblock(zmd, mblk);
		count++;
	}

	return count;
}

/*
 * For mblock shrinker: get the number of unused metadata blocks in the cache.
 */
static unsigned long dmz_mblock_shrinker_count(struct shrinker *shrink,
					       struct shrink_control *sc)
{
	struct dmz_metadata *zmd = container_of(shrink, struct dmz_metadata, mblk_shrinker);

	return atomic_read(&zmd->nr_mblks);
}

/*
 * For mblock shrinker: scan unused metadata blocks and shrink the cache.
 */
static unsigned long dmz_mblock_shrinker_scan(struct shrinker *shrink,
					      struct shrink_control *sc)
{
	struct dmz_metadata *zmd = container_of(shrink, struct dmz_metadata, mblk_shrinker);
	unsigned long count;

	spin_lock(&zmd->mblk_lock);
	count = dmz_shrink_mblock_cache(zmd, sc->nr_to_scan);
	spin_unlock(&zmd->mblk_lock);

	return count ? count : SHRINK_STOP;
}

/*
 * Release a metadata block.
 */
static void dmz_release_mblock(struct dmz_metadata *zmd,
			       struct dmz_mblock *mblk)
{

	if (!mblk)
		return;

	spin_lock(&zmd->mblk_lock);

	if (atomic_dec_and_test(&mblk->ref)) {
		if (test_bit(DMZ_META_ERROR, &mblk->state)) {
			rb_erase(&mblk->node, &zmd->mblk_rbtree);
			dmz_free_mblock(zmd, mblk);
		} else if (!test_bit(DMZ_META_DIRTY, &mblk->state)) {
			list_add_tail(&mblk->link, &zmd->mblk_lru_list);
			dmz_shrink_mblock_cache(zmd, 1);
		}
	}

	spin_unlock(&zmd->mblk_lock);
}

/*
 * Get a metadata block from the rbtree. If the block
 * is not present, read it from disk.
 */
static struct dmz_mblock *dmz_get_mblock(struct dmz_metadata *zmd,
					 sector_t mblk_no)
{
	struct dmz_mblock *mblk;

	/* Check rbtree */
	spin_lock(&zmd->mblk_lock);
	mblk = dmz_lookup_mblock(zmd, mblk_no);
	if (mblk) {
		/* Cache hit: remove block from LRU list */
		if (atomic_inc_return(&mblk->ref) == 1 &&
		    !test_bit(DMZ_META_DIRTY, &mblk->state))
			list_del_init(&mblk->link);
	}
	spin_unlock(&zmd->mblk_lock);

	if (!mblk) {
		/* Cache miss: read the block from disk */
		mblk = dmz_fetch_mblock(zmd, mblk_no);
		if (!mblk)
			return ERR_PTR(-ENOMEM);
	}

	/* Wait for on-going read I/O and check for error */
	wait_on_bit_io(&mblk->state, DMZ_META_READING,
		       TASK_UNINTERRUPTIBLE);
	if (test_bit(DMZ_META_ERROR, &mblk->state)) {
		dmz_release_mblock(zmd, mblk);
		return ERR_PTR(-EIO);
	}

	return mblk;
}

/*
 * Mark a metadata block dirty.
 */
static void dmz_dirty_mblock(struct dmz_metadata *zmd, struct dmz_mblock *mblk)
{
	spin_lock(&zmd->mblk_lock);
	if (!test_and_set_bit(DMZ_META_DIRTY, &mblk->state))
		list_add_tail(&mblk->link, &zmd->mblk_dirty_list);
	spin_unlock(&zmd->mblk_lock);
}

/*
 * Issue a metadata block write BIO.
 */
static void dmz_write_mblock(struct dmz_metadata *zmd, struct dmz_mblock *mblk,
			     unsigned int set)
{
	sector_t block = zmd->sb[set].block + mblk->no;
	struct bio *bio;

	bio = bio_alloc(GFP_NOIO, 1);
	if (!bio) {
		set_bit(DMZ_META_ERROR, &mblk->state);
		return;
	}

	set_bit(DMZ_META_WRITING, &mblk->state);

	bio->bi_iter.bi_sector = dmz_blk2sect(block);
	bio_set_dev(bio, zmd->dev->bdev);
	bio->bi_private = mblk;
	bio->bi_end_io = dmz_mblock_bio_end_io;
	bio_set_op_attrs(bio, REQ_OP_WRITE, REQ_META | REQ_PRIO);
	bio_add_page(bio, mblk->page, DMZ_BLOCK_SIZE, 0);
	submit_bio(bio);
}

/*
 * Read/write a metadata block.
 */
static int dmz_rdwr_block(struct dmz_metadata *zmd, int op, sector_t block,
			  struct page *page)
{
	struct bio *bio;
	int ret;

	bio = bio_alloc(GFP_NOIO, 1);
	if (!bio)
		return -ENOMEM;

	bio->bi_iter.bi_sector = dmz_blk2sect(block);
	bio_set_dev(bio, zmd->dev->bdev);
	bio_set_op_attrs(bio, op, REQ_SYNC | REQ_META | REQ_PRIO);
	bio_add_page(bio, page, DMZ_BLOCK_SIZE, 0);
	ret = submit_bio_wait(bio);
	bio_put(bio);

	return ret;
}

/*
 * Write super block of the specified metadata set.
 */
static int dmz_write_sb(struct dmz_metadata *zmd, unsigned int set)
{
	sector_t block = zmd->sb[set].block;
	struct dmz_mblock *mblk = zmd->sb[set].mblk;
	struct dmz_super *sb = zmd->sb[set].sb;
	u64 sb_gen = zmd->sb_gen + 1;
	int ret;

	sb->magic = cpu_to_le32(DMZ_MAGIC);
	sb->version = cpu_to_le32(DMZ_META_VER);

	sb->gen = cpu_to_le64(sb_gen);

	sb->sb_block = cpu_to_le64(block);
	sb->nr_meta_blocks = cpu_to_le32(zmd->nr_meta_blocks);
	sb->nr_reserved_seq = cpu_to_le32(zmd->nr_reserved_seq);
	sb->nr_chunks = cpu_to_le32(zmd->nr_chunks);

	sb->nr_map_blocks = cpu_to_le32(zmd->nr_map_blocks);
	sb->nr_bitmap_blocks = cpu_to_le32(zmd->nr_bitmap_blocks);

	sb->crc = 0;
	sb->crc = cpu_to_le32(crc32_le(sb_gen, (unsigned char *)sb, DMZ_BLOCK_SIZE));

	ret = dmz_rdwr_block(zmd, REQ_OP_WRITE, block, mblk->page);
	if (ret == 0)
		ret = blkdev_issue_flush(zmd->dev->bdev, GFP_NOIO, NULL);

	return ret;
}

/*
 * Write dirty metadata blocks to the specified set.
 */
static int dmz_write_dirty_mblocks(struct dmz_metadata *zmd,
				   struct list_head *write_list,
				   unsigned int set)
{
	struct dmz_mblock *mblk;
	struct blk_plug plug;
	int ret = 0;

	/* Issue writes */
	blk_start_plug(&plug);
	list_for_each_entry(mblk, write_list, link)
		dmz_write_mblock(zmd, mblk, set);
	blk_finish_plug(&plug);

	/* Wait for completion */
	list_for_each_entry(mblk, write_list, link) {
		wait_on_bit_io(&mblk->state, DMZ_META_WRITING,
			       TASK_UNINTERRUPTIBLE);
		if (test_bit(DMZ_META_ERROR, &mblk->state)) {
			clear_bit(DMZ_META_ERROR, &mblk->state);
			ret = -EIO;
		}
	}

	/* Flush drive cache (this will also sync data) */
	if (ret == 0)
		ret = blkdev_issue_flush(zmd->dev->bdev, GFP_NOIO, NULL);

	return ret;
}

/*
 * Log dirty metadata blocks.
 */
static int dmz_log_dirty_mblocks(struct dmz_metadata *zmd,
				 struct list_head *write_list)
{
	unsigned int log_set = zmd->mblk_primary ^ 0x1;
	int ret;

	/* Write dirty blocks to the log */
	ret = dmz_write_dirty_mblocks(zmd, write_list, log_set);
	if (ret)
		return ret;

	/*
	 * No error so far: now validate the log by updating the
	 * log index super block generation.
	 */
	ret = dmz_write_sb(zmd, log_set);
	if (ret)
		return ret;

	return 0;
}

/*
 * Flush dirty metadata blocks.
 */
int dmz_flush_metadata(struct dmz_metadata *zmd)
{
	struct dmz_mblock *mblk;
	struct list_head write_list;
	int ret;

	if (WARN_ON(!zmd))
		return 0;

	INIT_LIST_HEAD(&write_list);

	/*
	 * Make sure that metadata blocks are stable before logging: take
	 * the write lock on the metadata semaphore to prevent target BIOs
	 * from modifying metadata.
	 */
	down_write(&zmd->mblk_sem);

	/*
	 * This is called from the target flush work and reclaim work.
	 * Concurrent execution is not allowed.
	 */
	dmz_lock_flush(zmd);

	/* Get dirty blocks */
	spin_lock(&zmd->mblk_lock);
	list_splice_init(&zmd->mblk_dirty_list, &write_list);
	spin_unlock(&zmd->mblk_lock);

	/* If there are no dirty metadata blocks, just flush the device cache */
	if (list_empty(&write_list)) {
		ret = blkdev_issue_flush(zmd->dev->bdev, GFP_NOIO, NULL);
		goto out;
	}

	/*
	 * The primary metadata set is still clean. Keep it this way until
	 * all updates are successful in the secondary set. That is, use
	 * the secondary set as a log.
	 */
	ret = dmz_log_dirty_mblocks(zmd, &write_list);
	if (ret)
		goto out;

	/*
	 * The log is on disk. It is now safe to update in place
	 * in the primary metadata set.
	 */
	ret = dmz_write_dirty_mblocks(zmd, &write_list, zmd->mblk_primary);
	if (ret)
		goto out;

	ret = dmz_write_sb(zmd, zmd->mblk_primary);
	if (ret)
		goto out;

	while (!list_empty(&write_list)) {
		mblk = list_first_entry(&write_list, struct dmz_mblock, link);
		list_del_init(&mblk->link);

		spin_lock(&zmd->mblk_lock);
		clear_bit(DMZ_META_DIRTY, &mblk->state);
		if (atomic_read(&mblk->ref) == 0)
			list_add_tail(&mblk->link, &zmd->mblk_lru_list);
		spin_unlock(&zmd->mblk_lock);
	}

	zmd->sb_gen++;
out:
	if (ret && !list_empty(&write_list)) {
		spin_lock(&zmd->mblk_lock);
		list_splice(&write_list, &zmd->mblk_dirty_list);
		spin_unlock(&zmd->mblk_lock);
	}

	dmz_unlock_flush(zmd);
	up_write(&zmd->mblk_sem);

	return ret;
}

/*
 * Check super block.
 */
static int dmz_check_sb(struct dmz_metadata *zmd, struct dmz_super *sb)
{
	unsigned int nr_meta_zones, nr_data_zones;
	struct dmz_dev *dev = zmd->dev;
	u32 crc, stored_crc;
	u64 gen;

	gen = le64_to_cpu(sb->gen);
	stored_crc = le32_to_cpu(sb->crc);
	sb->crc = 0;
	crc = crc32_le(gen, (unsigned char *)sb, DMZ_BLOCK_SIZE);
	if (crc != stored_crc) {
		dmz_dev_err(dev, "Invalid checksum (needed 0x%08x, got 0x%08x)",
			    crc, stored_crc);
		return -ENXIO;
	}

	if (le32_to_cpu(sb->magic) != DMZ_MAGIC) {
		dmz_dev_err(dev, "Invalid meta magic (needed 0x%08x, got 0x%08x)",
			    DMZ_MAGIC, le32_to_cpu(sb->magic));
		return -ENXIO;
	}

	if (le32_to_cpu(sb->version) != DMZ_META_VER) {
		dmz_dev_err(dev, "Invalid meta version (needed %d, got %d)",
			    DMZ_META_VER, le32_to_cpu(sb->version));
		return -ENXIO;
	}

	nr_meta_zones = (le32_to_cpu(sb->nr_meta_blocks) + dev->zone_nr_blocks - 1)
		>> dev->zone_nr_blocks_shift;
	if (!nr_meta_zones ||
	    nr_meta_zones >= zmd->nr_rnd_zones) {
		dmz_dev_err(dev, "Invalid number of metadata blocks");
		return -ENXIO;
	}

	if (!le32_to_cpu(sb->nr_reserved_seq) ||
	    le32_to_cpu(sb->nr_reserved_seq) >= (zmd->nr_useable_zones - nr_meta_zones)) {
		dmz_dev_err(dev, "Invalid number of reserved sequential zones");
		return -ENXIO;
	}

	nr_data_zones = zmd->nr_useable_zones -
		(nr_meta_zones * 2 + le32_to_cpu(sb->nr_reserved_seq));
	if (le32_to_cpu(sb->nr_chunks) > nr_data_zones) {
		dmz_dev_err(dev, "Invalid number of chunks %u / %u",
			    le32_to_cpu(sb->nr_chunks), nr_data_zones);
		return -ENXIO;
	}

	/* OK */
	zmd->nr_meta_blocks = le32_to_cpu(sb->nr_meta_blocks);
	zmd->nr_reserved_seq = le32_to_cpu(sb->nr_reserved_seq);
	zmd->nr_chunks = le32_to_cpu(sb->nr_chunks);
	zmd->nr_map_blocks = le32_to_cpu(sb->nr_map_blocks);
	zmd->nr_bitmap_blocks = le32_to_cpu(sb->nr_bitmap_blocks);
	zmd->nr_meta_zones = nr_meta_zones;
	zmd->nr_data_zones = nr_data_zones;

	return 0;
}

/*
 * Read the first or second super block from disk.
 */
static int dmz_read_sb(struct dmz_metadata *zmd, unsigned int set)
{
	return dmz_rdwr_block(zmd, REQ_OP_READ, zmd->sb[set].block,
			      zmd->sb[set].mblk->page);
}

/*
 * Determine the position of the secondary super blocks on disk.
 * This is used only if a corruption of the primary super block
 * is detected.
 */
static int dmz_lookup_secondary_sb(struct dmz_metadata *zmd)
{
	unsigned int zone_nr_blocks = zmd->dev->zone_nr_blocks;
	struct dmz_mblock *mblk;
	int i;

	/* Allocate a block */
	mblk = dmz_alloc_mblock(zmd, 0);
	if (!mblk)
		return -ENOMEM;

	zmd->sb[1].mblk = mblk;
	zmd->sb[1].sb = mblk->data;

	/* Bad first super block: search for the second one */
	zmd->sb[1].block = zmd->sb[0].block + zone_nr_blocks;
	for (i = 0; i < zmd->nr_rnd_zones - 1; i++) {
		if (dmz_read_sb(zmd, 1) != 0)
			break;
		if (le32_to_cpu(zmd->sb[1].sb->magic) == DMZ_MAGIC)
			return 0;
		zmd->sb[1].block += zone_nr_blocks;
	}

	dmz_free_mblock(zmd, mblk);
	zmd->sb[1].mblk = NULL;

	return -EIO;
}

/*
 * Read the first or second super block from disk.
 */
static int dmz_get_sb(struct dmz_metadata *zmd, unsigned int set)
{
	struct dmz_mblock *mblk;
	int ret;

	/* Allocate a block */
	mblk = dmz_alloc_mblock(zmd, 0);
	if (!mblk)
		return -ENOMEM;

	zmd->sb[set].mblk = mblk;
	zmd->sb[set].sb = mblk->data;

	/* Read super block */
	ret = dmz_read_sb(zmd, set);
	if (ret) {
		dmz_free_mblock(zmd, mblk);
		zmd->sb[set].mblk = NULL;
		return ret;
	}

	return 0;
}

/*
 * Recover a metadata set.
 */
static int dmz_recover_mblocks(struct dmz_metadata *zmd, unsigned int dst_set)
{
	unsigned int src_set = dst_set ^ 0x1;
	struct page *page;
	int i, ret;

	dmz_dev_warn(zmd->dev, "Metadata set %u invalid: recovering", dst_set);

	if (dst_set == 0)
		zmd->sb[0].block = dmz_start_block(zmd, zmd->sb_zone);
	else {
		zmd->sb[1].block = zmd->sb[0].block +
			(zmd->nr_meta_zones << zmd->dev->zone_nr_blocks_shift);
	}

	page = alloc_page(GFP_NOIO);
	if (!page)
		return -ENOMEM;

	/* Copy metadata blocks */
	for (i = 1; i < zmd->nr_meta_blocks; i++) {
		ret = dmz_rdwr_block(zmd, REQ_OP_READ,
				     zmd->sb[src_set].block + i, page);
		if (ret)
			goto out;
		ret = dmz_rdwr_block(zmd, REQ_OP_WRITE,
				     zmd->sb[dst_set].block + i, page);
		if (ret)
			goto out;
	}

	/* Finalize with the super block */
	if (!zmd->sb[dst_set].mblk) {
		zmd->sb[dst_set].mblk = dmz_alloc_mblock(zmd, 0);
		if (!zmd->sb[dst_set].mblk) {
			ret = -ENOMEM;
			goto out;
		}
		zmd->sb[dst_set].sb = zmd->sb[dst_set].mblk->data;
	}

	ret = dmz_write_sb(zmd, dst_set);
out:
	__free_pages(page, 0);

	return ret;
}

/*
 * Get super block from disk.
 */
static int dmz_load_sb(struct dmz_metadata *zmd)
{
	bool sb_good[2] = {false, false};
	u64 sb_gen[2] = {0, 0};
	int ret;

	/* Read and check the primary super block */
	zmd->sb[0].block = dmz_start_block(zmd, zmd->sb_zone);
	ret = dmz_get_sb(zmd, 0);
	if (ret) {
		dmz_dev_err(zmd->dev, "Read primary super block failed");
		return ret;
	}

	ret = dmz_check_sb(zmd, zmd->sb[0].sb);

	/* Read and check secondary super block */
	if (ret == 0) {
		sb_good[0] = true;
		zmd->sb[1].block = zmd->sb[0].block +
			(zmd->nr_meta_zones << zmd->dev->zone_nr_blocks_shift);
		ret = dmz_get_sb(zmd, 1);
	} else
		ret = dmz_lookup_secondary_sb(zmd);

	if (ret) {
		dmz_dev_err(zmd->dev, "Read secondary super block failed");
		return ret;
	}

	ret = dmz_check_sb(zmd, zmd->sb[1].sb);
	if (ret == 0)
		sb_good[1] = true;

	/* Use highest generation sb first */
	if (!sb_good[0] && !sb_good[1]) {
		dmz_dev_err(zmd->dev, "No valid super block found");
		return -EIO;
	}

	if (sb_good[0])
		sb_gen[0] = le64_to_cpu(zmd->sb[0].sb->gen);
	else
		ret = dmz_recover_mblocks(zmd, 0);

	if (sb_good[1])
		sb_gen[1] = le64_to_cpu(zmd->sb[1].sb->gen);
	else
		ret = dmz_recover_mblocks(zmd, 1);

	if (ret) {
		dmz_dev_err(zmd->dev, "Recovery failed");
		return -EIO;
	}

	if (sb_gen[0] >= sb_gen[1]) {
		zmd->sb_gen = sb_gen[0];
		zmd->mblk_primary = 0;
	} else {
		zmd->sb_gen = sb_gen[1];
		zmd->mblk_primary = 1;
	}

	dmz_dev_debug(zmd->dev, "Using super block %u (gen %llu)",
		      zmd->mblk_primary, zmd->sb_gen);

	return 0;
}

/*
 * Initialize a zone descriptor.
 */
static int dmz_init_zone(struct dmz_metadata *zmd, struct dm_zone *zone,
			 struct blk_zone *blkz)
{
	struct dmz_dev *dev = zmd->dev;

	/* Ignore the eventual last runt (smaller) zone */
	if (blkz->len != dev->zone_nr_sectors) {
		if (blkz->start + blkz->len == dev->capacity)
			return 0;
		return -ENXIO;
	}

	INIT_LIST_HEAD(&zone->link);
	atomic_set(&zone->refcount, 0);
	zone->chunk = DMZ_MAP_UNMAPPED;

	if (blkz->type == BLK_ZONE_TYPE_CONVENTIONAL) {
		set_bit(DMZ_RND, &zone->flags);
		zmd->nr_rnd_zones++;
	} else if (blkz->type == BLK_ZONE_TYPE_SEQWRITE_REQ ||
		   blkz->type == BLK_ZONE_TYPE_SEQWRITE_PREF) {
		set_bit(DMZ_SEQ, &zone->flags);
	} else
		return -ENXIO;

	if (blkz->cond == BLK_ZONE_COND_OFFLINE)
		set_bit(DMZ_OFFLINE, &zone->flags);
	else if (blkz->cond == BLK_ZONE_COND_READONLY)
		set_bit(DMZ_READ_ONLY, &zone->flags);

	if (dmz_is_rnd(zone))
		zone->wp_block = 0;
	else
		zone->wp_block = dmz_sect2blk(blkz->wp - blkz->start);

	if (!dmz_is_offline(zone) && !dmz_is_readonly(zone)) {
		zmd->nr_useable_zones++;
		if (dmz_is_rnd(zone)) {
			zmd->nr_rnd_zones++;
			if (!zmd->sb_zone) {
				/* Super block zone */
				zmd->sb_zone = zone;
			}
		}
	}

	return 0;
}

/*
 * Free zones descriptors.
 */
static void dmz_drop_zones(struct dmz_metadata *zmd)
{
	kfree(zmd->zones);
	zmd->zones = NULL;
}

/*
 * The size of a zone report in number of zones.
 * This results in 4096*64B=256KB report zones commands.
 */
#define DMZ_REPORT_NR_ZONES	4096

/*
 * Allocate and initialize zone descriptors using the zone
 * information from disk.
 */
static int dmz_init_zones(struct dmz_metadata *zmd)
{
	struct dmz_dev *dev = zmd->dev;
	struct dm_zone *zone;
	struct blk_zone *blkz;
	unsigned int nr_blkz;
	sector_t sector = 0;
	int i, ret = 0;

	/* Init */
	zmd->zone_bitmap_size = dev->zone_nr_blocks >> 3;
	zmd->zone_nr_bitmap_blocks = zmd->zone_bitmap_size >> DMZ_BLOCK_SHIFT;

	/* Allocate zone array */
	zmd->zones = kcalloc(dev->nr_zones, sizeof(struct dm_zone), GFP_KERNEL);
	if (!zmd->zones)
		return -ENOMEM;

	dmz_dev_info(dev, "Using %zu B for zone information",
		     sizeof(struct dm_zone) * dev->nr_zones);

	/* Get zone information */
	nr_blkz = DMZ_REPORT_NR_ZONES;
	blkz = kcalloc(nr_blkz, sizeof(struct blk_zone), GFP_KERNEL);
	if (!blkz) {
		ret = -ENOMEM;
		goto out;
	}

	/*
	 * Get zone information and initialize zone descriptors.
	 * At the same time, determine where the super block
	 * should be: first block of the first randomly writable
	 * zone.
	 */
	zone = zmd->zones;
	while (sector < dev->capacity) {
		/* Get zone information */
		nr_blkz = DMZ_REPORT_NR_ZONES;
		ret = blkdev_report_zones(dev->bdev, sector, blkz,
					  &nr_blkz, GFP_KERNEL);
		if (ret) {
			dmz_dev_err(dev, "Report zones failed %d", ret);
			goto out;
		}

		/* Process report */
		for (i = 0; i < nr_blkz; i++) {
			ret = dmz_init_zone(zmd, zone, &blkz[i]);
			if (ret)
				goto out;
			sector += dev->zone_nr_sectors;
			zone++;
		}
	}

	/* The entire zone configuration of the disk should now be known */
	if (sector < dev->capacity) {
		dmz_dev_err(dev, "Failed to get correct zone information");
		ret = -ENXIO;
	}
out:
	kfree(blkz);
	if (ret)
		dmz_drop_zones(zmd);

	return ret;
}

/*
 * Update a zone information.
 */
static int dmz_update_zone(struct dmz_metadata *zmd, struct dm_zone *zone)
{
	unsigned int nr_blkz = 1;
	struct blk_zone blkz;
	int ret;

	/* Get zone information from disk */
	ret = blkdev_report_zones(zmd->dev->bdev, dmz_start_sect(zmd, zone),
				  &blkz, &nr_blkz, GFP_NOIO);
	if (ret) {
		dmz_dev_err(zmd->dev, "Get zone %u report failed",
			    dmz_id(zmd, zone));
		return ret;
	}

	clear_bit(DMZ_OFFLINE, &zone->flags);
	clear_bit(DMZ_READ_ONLY, &zone->flags);
	if (blkz.cond == BLK_ZONE_COND_OFFLINE)
		set_bit(DMZ_OFFLINE, &zone->flags);
	else if (blkz.cond == BLK_ZONE_COND_READONLY)
		set_bit(DMZ_READ_ONLY, &zone->flags);

	if (dmz_is_seq(zone))
		zone->wp_block = dmz_sect2blk(blkz.wp - blkz.start);
	else
		zone->wp_block = 0;

	return 0;
}

/*
 * Check a zone write pointer position when the zone is marked
 * with the sequential write error flag.
 */
static int dmz_handle_seq_write_err(struct dmz_metadata *zmd,
				    struct dm_zone *zone)
{
	unsigned int wp = 0;
	int ret;

	wp = zone->wp_block;
	ret = dmz_update_zone(zmd, zone);
	if (ret)
		return ret;

	dmz_dev_warn(zmd->dev, "Processing zone %u write error (zone wp %u/%u)",
		     dmz_id(zmd, zone), zone->wp_block, wp);

	if (zone->wp_block < wp) {
		dmz_invalidate_blocks(zmd, zone, zone->wp_block,
				      wp - zone->wp_block);
	}

	return 0;
}

static struct dm_zone *dmz_get(struct dmz_metadata *zmd, unsigned int zone_id)
{
	return &zmd->zones[zone_id];
}

/*
 * Reset a zone write pointer.
 */
static int dmz_reset_zone(struct dmz_metadata *zmd, struct dm_zone *zone)
{
	int ret;

	/*
	 * Ignore offline zones, read only zones,
	 * and conventional zones.
	 */
	if (dmz_is_offline(zone) ||
	    dmz_is_readonly(zone) ||
	    dmz_is_rnd(zone))
		return 0;

	if (!dmz_is_empty(zone) || dmz_seq_write_err(zone)) {
		struct dmz_dev *dev = zmd->dev;

		ret = blkdev_reset_zones(dev->bdev,
					 dmz_start_sect(zmd, zone),
					 dev->zone_nr_sectors, GFP_NOIO);
		if (ret) {
			dmz_dev_err(dev, "Reset zone %u failed %d",
				    dmz_id(zmd, zone), ret);
			return ret;
		}
	}

	/* Clear write error bit and rewind write pointer position */
	clear_bit(DMZ_SEQ_WRITE_ERR, &zone->flags);
	zone->wp_block = 0;

	return 0;
}

static void dmz_get_zone_weight(struct dmz_metadata *zmd, struct dm_zone *zone);

/*
 * Initialize chunk mapping.
 */
static int dmz_load_mapping(struct dmz_metadata *zmd)
{
	struct dmz_dev *dev = zmd->dev;
	struct dm_zone *dzone, *bzone;
	struct dmz_mblock *dmap_mblk = NULL;
	struct dmz_map *dmap;
	unsigned int i = 0, e = 0, chunk = 0;
	unsigned int dzone_id;
	unsigned int bzone_id;

	/* Metadata block array for the chunk mapping table */
	zmd->map_mblk = kcalloc(zmd->nr_map_blocks,
				sizeof(struct dmz_mblk *), GFP_KERNEL);
	if (!zmd->map_mblk)
		return -ENOMEM;

	/* Get chunk mapping table blocks and initialize zone mapping */
	while (chunk < zmd->nr_chunks) {
		if (!dmap_mblk) {
			/* Get mapping block */
			dmap_mblk = dmz_get_mblock(zmd, i + 1);
			if (IS_ERR(dmap_mblk))
				return PTR_ERR(dmap_mblk);
			zmd->map_mblk[i] = dmap_mblk;
			dmap = (struct dmz_map *) dmap_mblk->data;
			i++;
			e = 0;
		}

		/* Check data zone */
		dzone_id = le32_to_cpu(dmap[e].dzone_id);
		if (dzone_id == DMZ_MAP_UNMAPPED)
			goto next;

		if (dzone_id >= dev->nr_zones) {
			dmz_dev_err(dev, "Chunk %u mapping: invalid data zone ID %u",
				    chunk, dzone_id);
			return -EIO;
		}

		dzone = dmz_get(zmd, dzone_id);
		set_bit(DMZ_DATA, &dzone->flags);
		dzone->chunk = chunk;
		dmz_get_zone_weight(zmd, dzone);

		if (dmz_is_rnd(dzone))
			list_add_tail(&dzone->link, &zmd->map_rnd_list);
		else
			list_add_tail(&dzone->link, &zmd->map_seq_list);

		/* Check buffer zone */
		bzone_id = le32_to_cpu(dmap[e].bzone_id);
		if (bzone_id == DMZ_MAP_UNMAPPED)
			goto next;

		if (bzone_id >= dev->nr_zones) {
			dmz_dev_err(dev, "Chunk %u mapping: invalid buffer zone ID %u",
				    chunk, bzone_id);
			return -EIO;
		}

		bzone = dmz_get(zmd, bzone_id);
		if (!dmz_is_rnd(bzone)) {
			dmz_dev_err(dev, "Chunk %u mapping: invalid buffer zone %u",
				    chunk, bzone_id);
			return -EIO;
		}

		set_bit(DMZ_DATA, &bzone->flags);
		set_bit(DMZ_BUF, &bzone->flags);
		bzone->chunk = chunk;
		bzone->bzone = dzone;
		dzone->bzone = bzone;
		dmz_get_zone_weight(zmd, bzone);
		list_add_tail(&bzone->link, &zmd->map_rnd_list);
next:
		chunk++;
		e++;
		if (e >= DMZ_MAP_ENTRIES)
			dmap_mblk = NULL;
	}

	/*
	 * At this point, only meta zones and mapped data zones were
	 * fully initialized. All remaining zones are unmapped data
	 * zones. Finish initializing those here.
	 */
	for (i = 0; i < dev->nr_zones; i++) {
		dzone = dmz_get(zmd, i);
		if (dmz_is_meta(dzone))
			continue;

		if (dmz_is_rnd(dzone))
			zmd->nr_rnd++;
		else
			zmd->nr_seq++;

		if (dmz_is_data(dzone)) {
			/* Already initialized */
			continue;
		}

		/* Unmapped data zone */
		set_bit(DMZ_DATA, &dzone->flags);
		dzone->chunk = DMZ_MAP_UNMAPPED;
		if (dmz_is_rnd(dzone)) {
			list_add_tail(&dzone->link, &zmd->unmap_rnd_list);
			atomic_inc(&zmd->unmap_nr_rnd);
		} else if (atomic_read(&zmd->nr_reserved_seq_zones) < zmd->nr_reserved_seq) {
			list_add_tail(&dzone->link, &zmd->reserved_seq_zones_list);
			atomic_inc(&zmd->nr_reserved_seq_zones);
			zmd->nr_seq--;
		} else {
			list_add_tail(&dzone->link, &zmd->unmap_seq_list);
			atomic_inc(&zmd->unmap_nr_seq);
		}
	}

	return 0;
}

/*
 * Set a data chunk mapping.
 */
static void dmz_set_chunk_mapping(struct dmz_metadata *zmd, unsigned int chunk,
				  unsigned int dzone_id, unsigned int bzone_id)
{
	struct dmz_mblock *dmap_mblk = zmd->map_mblk[chunk >> DMZ_MAP_ENTRIES_SHIFT];
	struct dmz_map *dmap = (struct dmz_map *) dmap_mblk->data;
	int map_idx = chunk & DMZ_MAP_ENTRIES_MASK;

	dmap[map_idx].dzone_id = cpu_to_le32(dzone_id);
	dmap[map_idx].bzone_id = cpu_to_le32(bzone_id);
	dmz_dirty_mblock(zmd, dmap_mblk);
}

/*
 * The list of mapped zones is maintained in LRU order.
 * This rotates a zone at the end of its map list.
 */
static void __dmz_lru_zone(struct dmz_metadata *zmd, struct dm_zone *zone)
{
	if (list_empty(&zone->link))
		return;

	list_del_init(&zone->link);
	if (dmz_is_seq(zone)) {
		/* LRU rotate sequential zone */
		list_add_tail(&zone->link, &zmd->map_seq_list);
	} else {
		/* LRU rotate random zone */
		list_add_tail(&zone->link, &zmd->map_rnd_list);
	}
}

/*
 * The list of mapped random zones is maintained
 * in LRU order. This rotates a zone at the end of the list.
 */
static void dmz_lru_zone(struct dmz_metadata *zmd, struct dm_zone *zone)
{
	__dmz_lru_zone(zmd, zone);
	if (zone->bzone)
		__dmz_lru_zone(zmd, zone->bzone);
}

/*
 * Wait for any zone to be freed.
 */
static void dmz_wait_for_free_zones(struct dmz_metadata *zmd)
{
	DEFINE_WAIT(wait);

	prepare_to_wait(&zmd->free_wq, &wait, TASK_UNINTERRUPTIBLE);
	dmz_unlock_map(zmd);
	dmz_unlock_metadata(zmd);

	io_schedule_timeout(HZ);

	dmz_lock_metadata(zmd);
	dmz_lock_map(zmd);
	finish_wait(&zmd->free_wq, &wait);
}

/*
 * Lock a zone for reclaim (set the zone RECLAIM bit).
 * Returns false if the zone cannot be locked or if it is already locked
 * and 1 otherwise.
 */
int dmz_lock_zone_reclaim(struct dm_zone *zone)
{
	/* Active zones cannot be reclaimed */
	if (dmz_is_active(zone))
		return 0;

	return !test_and_set_bit(DMZ_RECLAIM, &zone->flags);
}

/*
 * Clear a zone reclaim flag.
 */
void dmz_unlock_zone_reclaim(struct dm_zone *zone)
{
	WARN_ON(dmz_is_active(zone));
	WARN_ON(!dmz_in_reclaim(zone));

	clear_bit_unlock(DMZ_RECLAIM, &zone->flags);
	smp_mb__after_atomic();
	wake_up_bit(&zone->flags, DMZ_RECLAIM);
}

/*
 * Wait for a zone reclaim to complete.
 */
static void dmz_wait_for_reclaim(struct dmz_metadata *zmd, struct dm_zone *zone)
{
	dmz_unlock_map(zmd);
	dmz_unlock_metadata(zmd);
	wait_on_bit_timeout(&zone->flags, DMZ_RECLAIM, TASK_UNINTERRUPTIBLE, HZ);
	dmz_lock_metadata(zmd);
	dmz_lock_map(zmd);
}

/*
 * Select a random write zone for reclaim.
 */
static struct dm_zone *dmz_get_rnd_zone_for_reclaim(struct dmz_metadata *zmd)
{
	struct dm_zone *dzone = NULL;
	struct dm_zone *zone;

	if (list_empty(&zmd->map_rnd_list))
		return NULL;

	list_for_each_entry(zone, &zmd->map_rnd_list, link) {
		if (dmz_is_buf(zone))
			dzone = zone->bzone;
		else
			dzone = zone;
		if (dmz_lock_zone_reclaim(dzone))
			return dzone;
	}

	return NULL;
}

/*
 * Select a buffered sequential zone for reclaim.
 */
static struct dm_zone *dmz_get_seq_zone_for_reclaim(struct dmz_metadata *zmd)
{
	struct dm_zone *zone;

	if (list_empty(&zmd->map_seq_list))
		return NULL;

	list_for_each_entry(zone, &zmd->map_seq_list, link) {
		if (!zone->bzone)
			continue;
		if (dmz_lock_zone_reclaim(zone))
			return zone;
	}

	return NULL;
}

/*
 * Select a zone for reclaim.
 */
struct dm_zone *dmz_get_zone_for_reclaim(struct dmz_metadata *zmd)
{
	struct dm_zone *zone;

	/*
	 * Search for a zone candidate to reclaim: 2 cases are possible.
	 * (1) There is no free sequential zones. Then a random data zone
	 *     cannot be reclaimed. So choose a sequential zone to reclaim so
	 *     that afterward a random zone can be reclaimed.
	 * (2) At least one free sequential zone is available, then choose
	 *     the oldest random zone (data or buffer) that can be locked.
	 */
	dmz_lock_map(zmd);
	if (list_empty(&zmd->reserved_seq_zones_list))
		zone = dmz_get_seq_zone_for_reclaim(zmd);
	else
		zone = dmz_get_rnd_zone_for_reclaim(zmd);
	dmz_unlock_map(zmd);

	return zone;
}

/*
 * Activate a zone (increment its reference count).
 */
void dmz_activate_zone(struct dm_zone *zone)
{
	set_bit(DMZ_ACTIVE, &zone->flags);
	atomic_inc(&zone->refcount);
}

/*
 * Deactivate a zone. This decrement the zone reference counter
 * and clears the active state of the zone once the count reaches 0,
 * indicating that all BIOs to the zone have completed. Returns
 * true if the zone was deactivated.
 */
void dmz_deactivate_zone(struct dm_zone *zone)
{
	if (atomic_dec_and_test(&zone->refcount)) {
		WARN_ON(!test_bit(DMZ_ACTIVE, &zone->flags));
		clear_bit_unlock(DMZ_ACTIVE, &zone->flags);
		smp_mb__after_atomic();
	}
}

/*
 * Get the zone mapping a chunk, if the chunk is mapped already.
 * If no mapping exist and the operation is WRITE, a zone is
 * allocated and used to map the chunk.
 * The zone returned will be set to the active state.
 */
struct dm_zone *dmz_get_chunk_mapping(struct dmz_metadata *zmd, unsigned int chunk, int op)
{
	struct dmz_mblock *dmap_mblk = zmd->map_mblk[chunk >> DMZ_MAP_ENTRIES_SHIFT];
	struct dmz_map *dmap = (struct dmz_map *) dmap_mblk->data;
	int dmap_idx = chunk & DMZ_MAP_ENTRIES_MASK;
	unsigned int dzone_id;
	struct dm_zone *dzone = NULL;
	int ret = 0;

	dmz_lock_map(zmd);
again:
	/* Get the chunk mapping */
	dzone_id = le32_to_cpu(dmap[dmap_idx].dzone_id);
	if (dzone_id == DMZ_MAP_UNMAPPED) {
		/*
		 * Read or discard in unmapped chunks are fine. But for
		 * writes, we need a mapping, so get one.
		 */
		if (op != REQ_OP_WRITE)
			goto out;

		/* Alloate a random zone */
		dzone = dmz_alloc_zone(zmd, DMZ_ALLOC_RND);
		if (!dzone) {
			dmz_wait_for_free_zones(zmd);
			goto again;
		}

		dmz_map_zone(zmd, dzone, chunk);

	} else {
		/* The chunk is already mapped: get the mapping zone */
		dzone = dmz_get(zmd, dzone_id);
		if (dzone->chunk != chunk) {
			dzone = ERR_PTR(-EIO);
			goto out;
		}

		/* Repair write pointer if the sequential dzone has error */
		if (dmz_seq_write_err(dzone)) {
			ret = dmz_handle_seq_write_err(zmd, dzone);
			if (ret) {
				dzone = ERR_PTR(-EIO);
				goto out;
			}
			clear_bit(DMZ_SEQ_WRITE_ERR, &dzone->flags);
		}
	}

	/*
	 * If the zone is being reclaimed, the chunk mapping may change
	 * to a different zone. So wait for reclaim and retry. Otherwise,
	 * activate the zone (this will prevent reclaim from touching it).
	 */
	if (dmz_in_reclaim(dzone)) {
		dmz_wait_for_reclaim(zmd, dzone);
		goto again;
	}
	dmz_activate_zone(dzone);
	dmz_lru_zone(zmd, dzone);
out:
	dmz_unlock_map(zmd);

	return dzone;
}

/*
 * Write and discard change the block validity of data zones and their buffer
 * zones. Check here that valid blocks are still present. If all blocks are
 * invalid, the zones can be unmapped on the fly without waiting for reclaim
 * to do it.
 */
void dmz_put_chunk_mapping(struct dmz_metadata *zmd, struct dm_zone *dzone)
{
	struct dm_zone *bzone;

	dmz_lock_map(zmd);

	bzone = dzone->bzone;
	if (bzone) {
		if (dmz_weight(bzone))
			dmz_lru_zone(zmd, bzone);
		else {
			/* Empty buffer zone: reclaim it */
			dmz_unmap_zone(zmd, bzone);
			dmz_free_zone(zmd, bzone);
			bzone = NULL;
		}
	}

	/* Deactivate the data zone */
	dmz_deactivate_zone(dzone);
	if (dmz_is_active(dzone) || bzone || dmz_weight(dzone))
		dmz_lru_zone(zmd, dzone);
	else {
		/* Unbuffered inactive empty data zone: reclaim it */
		dmz_unmap_zone(zmd, dzone);
		dmz_free_zone(zmd, dzone);
	}

	dmz_unlock_map(zmd);
}

/*
 * Allocate and map a random zone to buffer a chunk
 * already mapped to a sequential zone.
 */
struct dm_zone *dmz_get_chunk_buffer(struct dmz_metadata *zmd,
				     struct dm_zone *dzone)
{
	struct dm_zone *bzone;

	dmz_lock_map(zmd);
again:
	bzone = dzone->bzone;
	if (bzone)
		goto out;

	/* Alloate a random zone */
	bzone = dmz_alloc_zone(zmd, DMZ_ALLOC_RND);
	if (!bzone) {
		dmz_wait_for_free_zones(zmd);
		goto again;
	}

	/* Update the chunk mapping */
	dmz_set_chunk_mapping(zmd, dzone->chunk, dmz_id(zmd, dzone),
			      dmz_id(zmd, bzone));

	set_bit(DMZ_BUF, &bzone->flags);
	bzone->chunk = dzone->chunk;
	bzone->bzone = dzone;
	dzone->bzone = bzone;
	list_add_tail(&bzone->link, &zmd->map_rnd_list);
out:
	dmz_unlock_map(zmd);

	return bzone;
}

/*
 * Get an unmapped (free) zone.
 * This must be called with the mapping lock held.
 */
struct dm_zone *dmz_alloc_zone(struct dmz_metadata *zmd, unsigned long flags)
{
	struct list_head *list;
	struct dm_zone *zone;

	if (flags & DMZ_ALLOC_RND)
		list = &zmd->unmap_rnd_list;
	else
		list = &zmd->unmap_seq_list;
again:
	if (list_empty(list)) {
		/*
		 * No free zone: if this is for reclaim, allow using the
		 * reserved sequential zones.
		 */
		if (!(flags & DMZ_ALLOC_RECLAIM) ||
		    list_empty(&zmd->reserved_seq_zones_list))
			return NULL;

		zone = list_first_entry(&zmd->reserved_seq_zones_list,
					struct dm_zone, link);
		list_del_init(&zone->link);
		atomic_dec(&zmd->nr_reserved_seq_zones);
		return zone;
	}

	zone = list_first_entry(list, struct dm_zone, link);
	list_del_init(&zone->link);

	if (dmz_is_rnd(zone))
		atomic_dec(&zmd->unmap_nr_rnd);
	else
		atomic_dec(&zmd->unmap_nr_seq);

	if (dmz_is_offline(zone)) {
		dmz_dev_warn(zmd->dev, "Zone %u is offline", dmz_id(zmd, zone));
		zone = NULL;
		goto again;
	}

	return zone;
}

/*
 * Free a zone.
 * This must be called with the mapping lock held.
 */
void dmz_free_zone(struct dmz_metadata *zmd, struct dm_zone *zone)
{
	/* If this is a sequential zone, reset it */
	if (dmz_is_seq(zone))
		dmz_reset_zone(zmd, zone);

	/* Return the zone to its type unmap list */
	if (dmz_is_rnd(zone)) {
		list_add_tail(&zone->link, &zmd->unmap_rnd_list);
		atomic_inc(&zmd->unmap_nr_rnd);
	} else if (atomic_read(&zmd->nr_reserved_seq_zones) <
		   zmd->nr_reserved_seq) {
		list_add_tail(&zone->link, &zmd->reserved_seq_zones_list);
		atomic_inc(&zmd->nr_reserved_seq_zones);
	} else {
		list_add_tail(&zone->link, &zmd->unmap_seq_list);
		atomic_inc(&zmd->unmap_nr_seq);
	}

	wake_up_all(&zmd->free_wq);
}

/*
 * Map a chunk to a zone.
 * This must be called with the mapping lock held.
 */
void dmz_map_zone(struct dmz_metadata *zmd, struct dm_zone *dzone,
		  unsigned int chunk)
{
	/* Set the chunk mapping */
	dmz_set_chunk_mapping(zmd, chunk, dmz_id(zmd, dzone),
			      DMZ_MAP_UNMAPPED);
	dzone->chunk = chunk;
	if (dmz_is_rnd(dzone))
		list_add_tail(&dzone->link, &zmd->map_rnd_list);
	else
		list_add_tail(&dzone->link, &zmd->map_seq_list);
}

/*
 * Unmap a zone.
 * This must be called with the mapping lock held.
 */
void dmz_unmap_zone(struct dmz_metadata *zmd, struct dm_zone *zone)
{
	unsigned int chunk = zone->chunk;
	unsigned int dzone_id;

	if (chunk == DMZ_MAP_UNMAPPED) {
		/* Already unmapped */
		return;
	}

	if (test_and_clear_bit(DMZ_BUF, &zone->flags)) {
		/*
		 * Unmapping the chunk buffer zone: clear only
		 * the chunk buffer mapping
		 */
		dzone_id = dmz_id(zmd, zone->bzone);
		zone->bzone->bzone = NULL;
		zone->bzone = NULL;

	} else {
		/*
		 * Unmapping the chunk data zone: the zone must
		 * not be buffered.
		 */
		if (WARN_ON(zone->bzone)) {
			zone->bzone->bzone = NULL;
			zone->bzone = NULL;
		}
		dzone_id = DMZ_MAP_UNMAPPED;
	}

	dmz_set_chunk_mapping(zmd, chunk, dzone_id, DMZ_MAP_UNMAPPED);

	zone->chunk = DMZ_MAP_UNMAPPED;
	list_del_init(&zone->link);
}

/*
 * Set @nr_bits bits in @bitmap starting from @bit.
 * Return the number of bits changed from 0 to 1.
 */
static unsigned int dmz_set_bits(unsigned long *bitmap,
				 unsigned int bit, unsigned int nr_bits)
{
	unsigned long *addr;
	unsigned int end = bit + nr_bits;
	unsigned int n = 0;

	while (bit < end) {
		if (((bit & (BITS_PER_LONG - 1)) == 0) &&
		    ((end - bit) >= BITS_PER_LONG)) {
			/* Try to set the whole word at once */
			addr = bitmap + BIT_WORD(bit);
			if (*addr == 0) {
				*addr = ULONG_MAX;
				n += BITS_PER_LONG;
				bit += BITS_PER_LONG;
				continue;
			}
		}

		if (!test_and_set_bit(bit, bitmap))
			n++;
		bit++;
	}

	return n;
}

/*
 * Get the bitmap block storing the bit for chunk_block in zone.
 */
static struct dmz_mblock *dmz_get_bitmap(struct dmz_metadata *zmd,
					 struct dm_zone *zone,
					 sector_t chunk_block)
{
	sector_t bitmap_block = 1 + zmd->nr_map_blocks +
		(sector_t)(dmz_id(zmd, zone) * zmd->zone_nr_bitmap_blocks) +
		(chunk_block >> DMZ_BLOCK_SHIFT_BITS);

	return dmz_get_mblock(zmd, bitmap_block);
}

/*
 * Copy the valid blocks bitmap of from_zone to the bitmap of to_zone.
 */
int dmz_copy_valid_blocks(struct dmz_metadata *zmd, struct dm_zone *from_zone,
			  struct dm_zone *to_zone)
{
	struct dmz_mblock *from_mblk, *to_mblk;
	sector_t chunk_block = 0;

	/* Get the zones bitmap blocks */
	while (chunk_block < zmd->dev->zone_nr_blocks) {
		from_mblk = dmz_get_bitmap(zmd, from_zone, chunk_block);
		if (IS_ERR(from_mblk))
			return PTR_ERR(from_mblk);
		to_mblk = dmz_get_bitmap(zmd, to_zone, chunk_block);
		if (IS_ERR(to_mblk)) {
			dmz_release_mblock(zmd, from_mblk);
			return PTR_ERR(to_mblk);
		}

		memcpy(to_mblk->data, from_mblk->data, DMZ_BLOCK_SIZE);
		dmz_dirty_mblock(zmd, to_mblk);

		dmz_release_mblock(zmd, to_mblk);
		dmz_release_mblock(zmd, from_mblk);

		chunk_block += DMZ_BLOCK_SIZE_BITS;
	}

	to_zone->weight = from_zone->weight;

	return 0;
}

/*
 * Merge the valid blocks bitmap of from_zone into the bitmap of to_zone,
 * starting from chunk_block.
 */
int dmz_merge_valid_blocks(struct dmz_metadata *zmd, struct dm_zone *from_zone,
			   struct dm_zone *to_zone, sector_t chunk_block)
{
	unsigned int nr_blocks;
	int ret;

	/* Get the zones bitmap blocks */
	while (chunk_block < zmd->dev->zone_nr_blocks) {
		/* Get a valid region from the source zone */
		ret = dmz_first_valid_block(zmd, from_zone, &chunk_block);
		if (ret <= 0)
			return ret;

		nr_blocks = ret;
		ret = dmz_validate_blocks(zmd, to_zone, chunk_block, nr_blocks);
		if (ret)
			return ret;

		chunk_block += nr_blocks;
	}

	return 0;
}

/*
 * Validate all the blocks in the range [block..block+nr_blocks-1].
 */
int dmz_validate_blocks(struct dmz_metadata *zmd, struct dm_zone *zone,
			sector_t chunk_block, unsigned int nr_blocks)
{
	unsigned int count, bit, nr_bits;
	unsigned int zone_nr_blocks = zmd->dev->zone_nr_blocks;
	struct dmz_mblock *mblk;
	unsigned int n = 0;

	dmz_dev_debug(zmd->dev, "=> VALIDATE zone %u, block %llu, %u blocks",
		      dmz_id(zmd, zone), (unsigned long long)chunk_block,
		      nr_blocks);

	WARN_ON(chunk_block + nr_blocks > zone_nr_blocks);

	while (nr_blocks) {
		/* Get bitmap block */
		mblk = dmz_get_bitmap(zmd, zone, chunk_block);
		if (IS_ERR(mblk))
			return PTR_ERR(mblk);

		/* Set bits */
		bit = chunk_block & DMZ_BLOCK_MASK_BITS;
		nr_bits = min(nr_blocks, DMZ_BLOCK_SIZE_BITS - bit);

		count = dmz_set_bits((unsigned long *)mblk->data, bit, nr_bits);
		if (count) {
			dmz_dirty_mblock(zmd, mblk);
			n += count;
		}
		dmz_release_mblock(zmd, mblk);

		nr_blocks -= nr_bits;
		chunk_block += nr_bits;
	}

	if (likely(zone->weight + n <= zone_nr_blocks))
		zone->weight += n;
	else {
		dmz_dev_warn(zmd->dev, "Zone %u: weight %u should be <= %u",
			     dmz_id(zmd, zone), zone->weight,
			     zone_nr_blocks - n);
		zone->weight = zone_nr_blocks;
	}

	return 0;
}

/*
 * Clear nr_bits bits in bitmap starting from bit.
 * Return the number of bits cleared.
 */
static int dmz_clear_bits(unsigned long *bitmap, int bit, int nr_bits)
{
	unsigned long *addr;
	int end = bit + nr_bits;
	int n = 0;

	while (bit < end) {
		if (((bit & (BITS_PER_LONG - 1)) == 0) &&
		    ((end - bit) >= BITS_PER_LONG)) {
			/* Try to clear whole word at once */
			addr = bitmap + BIT_WORD(bit);
			if (*addr == ULONG_MAX) {
				*addr = 0;
				n += BITS_PER_LONG;
				bit += BITS_PER_LONG;
				continue;
			}
		}

		if (test_and_clear_bit(bit, bitmap))
			n++;
		bit++;
	}

	return n;
}

/*
 * Invalidate all the blocks in the range [block..block+nr_blocks-1].
 */
int dmz_invalidate_blocks(struct dmz_metadata *zmd, struct dm_zone *zone,
			  sector_t chunk_block, unsigned int nr_blocks)
{
	unsigned int count, bit, nr_bits;
	struct dmz_mblock *mblk;
	unsigned int n = 0;

	dmz_dev_debug(zmd->dev, "=> INVALIDATE zone %u, block %llu, %u blocks",
		      dmz_id(zmd, zone), (u64)chunk_block, nr_blocks);

	WARN_ON(chunk_block + nr_blocks > zmd->dev->zone_nr_blocks);

	while (nr_blocks) {
		/* Get bitmap block */
		mblk = dmz_get_bitmap(zmd, zone, chunk_block);
		if (IS_ERR(mblk))
			return PTR_ERR(mblk);

		/* Clear bits */
		bit = chunk_block & DMZ_BLOCK_MASK_BITS;
		nr_bits = min(nr_blocks, DMZ_BLOCK_SIZE_BITS - bit);

		count = dmz_clear_bits((unsigned long *)mblk->data,
				       bit, nr_bits);
		if (count) {
			dmz_dirty_mblock(zmd, mblk);
			n += count;
		}
		dmz_release_mblock(zmd, mblk);

		nr_blocks -= nr_bits;
		chunk_block += nr_bits;
	}

	if (zone->weight >= n)
		zone->weight -= n;
	else {
		dmz_dev_warn(zmd->dev, "Zone %u: weight %u should be >= %u",
			     dmz_id(zmd, zone), zone->weight, n);
		zone->weight = 0;
	}

	return 0;
}

/*
 * Get a block bit value.
 */
static int dmz_test_block(struct dmz_metadata *zmd, struct dm_zone *zone,
			  sector_t chunk_block)
{
	struct dmz_mblock *mblk;
	int ret;

	WARN_ON(chunk_block >= zmd->dev->zone_nr_blocks);

	/* Get bitmap block */
	mblk = dmz_get_bitmap(zmd, zone, chunk_block);
	if (IS_ERR(mblk))
		return PTR_ERR(mblk);

	/* Get offset */
	ret = test_bit(chunk_block & DMZ_BLOCK_MASK_BITS,
		       (unsigned long *) mblk->data) != 0;

	dmz_release_mblock(zmd, mblk);

	return ret;
}

/*
 * Return the number of blocks from chunk_block to the first block with a bit
 * value specified by set. Search at most nr_blocks blocks from chunk_block.
 */
static int dmz_to_next_set_block(struct dmz_metadata *zmd, struct dm_zone *zone,
				 sector_t chunk_block, unsigned int nr_blocks,
				 int set)
{
	struct dmz_mblock *mblk;
	unsigned int bit, set_bit, nr_bits;
	unsigned long *bitmap;
	int n = 0;

	WARN_ON(chunk_block + nr_blocks > zmd->dev->zone_nr_blocks);

	while (nr_blocks) {
		/* Get bitmap block */
		mblk = dmz_get_bitmap(zmd, zone, chunk_block);
		if (IS_ERR(mblk))
			return PTR_ERR(mblk);

		/* Get offset */
		bitmap = (unsigned long *) mblk->data;
		bit = chunk_block & DMZ_BLOCK_MASK_BITS;
		nr_bits = min(nr_blocks, DMZ_BLOCK_SIZE_BITS - bit);
		if (set)
			set_bit = find_next_bit(bitmap, DMZ_BLOCK_SIZE_BITS, bit);
		else
			set_bit = find_next_zero_bit(bitmap, DMZ_BLOCK_SIZE_BITS, bit);
		dmz_release_mblock(zmd, mblk);

		n += set_bit - bit;
		if (set_bit < DMZ_BLOCK_SIZE_BITS)
			break;

		nr_blocks -= nr_bits;
		chunk_block += nr_bits;
	}

	return n;
}

/*
 * Test if chunk_block is valid. If it is, the number of consecutive
 * valid blocks from chunk_block will be returned.
 */
int dmz_block_valid(struct dmz_metadata *zmd, struct dm_zone *zone,
		    sector_t chunk_block)
{
	int valid;

	valid = dmz_test_block(zmd, zone, chunk_block);
	if (valid <= 0)
		return valid;

	/* The block is valid: get the number of valid blocks from block */
	return dmz_to_next_set_block(zmd, zone, chunk_block,
				     zmd->dev->zone_nr_blocks - chunk_block, 0);
}

/*
 * Find the first valid block from @chunk_block in @zone.
 * If such a block is found, its number is returned using
 * @chunk_block and the total number of valid blocks from @chunk_block
 * is returned.
 */
int dmz_first_valid_block(struct dmz_metadata *zmd, struct dm_zone *zone,
			  sector_t *chunk_block)
{
	sector_t start_block = *chunk_block;
	int ret;

	ret = dmz_to_next_set_block(zmd, zone, start_block,
				    zmd->dev->zone_nr_blocks - start_block, 1);
	if (ret < 0)
		return ret;

	start_block += ret;
	*chunk_block = start_block;

	return dmz_to_next_set_block(zmd, zone, start_block,
				     zmd->dev->zone_nr_blocks - start_block, 0);
}

/*
 * Count the number of bits set starting from bit up to bit + nr_bits - 1.
 */
static int dmz_count_bits(void *bitmap, int bit, int nr_bits)
{
	unsigned long *addr;
	int end = bit + nr_bits;
	int n = 0;

	while (bit < end) {
		if (((bit & (BITS_PER_LONG - 1)) == 0) &&
		    ((end - bit) >= BITS_PER_LONG)) {
			addr = (unsigned long *)bitmap + BIT_WORD(bit);
			if (*addr == ULONG_MAX) {
				n += BITS_PER_LONG;
				bit += BITS_PER_LONG;
				continue;
			}
		}

		if (test_bit(bit, bitmap))
			n++;
		bit++;
	}

	return n;
}

/*
 * Get a zone weight.
 */
static void dmz_get_zone_weight(struct dmz_metadata *zmd, struct dm_zone *zone)
{
	struct dmz_mblock *mblk;
	sector_t chunk_block = 0;
	unsigned int bit, nr_bits;
	unsigned int nr_blocks = zmd->dev->zone_nr_blocks;
	void *bitmap;
	int n = 0;

	while (nr_blocks) {
		/* Get bitmap block */
		mblk = dmz_get_bitmap(zmd, zone, chunk_block);
		if (IS_ERR(mblk)) {
			n = 0;
			break;
		}

		/* Count bits in this block */
		bitmap = mblk->data;
		bit = chunk_block & DMZ_BLOCK_MASK_BITS;
		nr_bits = min(nr_blocks, DMZ_BLOCK_SIZE_BITS - bit);
		n += dmz_count_bits(bitmap, bit, nr_bits);

		dmz_release_mblock(zmd, mblk);

		nr_blocks -= nr_bits;
		chunk_block += nr_bits;
	}

	zone->weight = n;
}

/*
 * Cleanup the zoned metadata resources.
 */
static void dmz_cleanup_metadata(struct dmz_metadata *zmd)
{
	struct rb_root *root;
	struct dmz_mblock *mblk, *next;
	int i;

	/* Release zone mapping resources */
	if (zmd->map_mblk) {
		for (i = 0; i < zmd->nr_map_blocks; i++)
			dmz_release_mblock(zmd, zmd->map_mblk[i]);
		kfree(zmd->map_mblk);
		zmd->map_mblk = NULL;
	}

	/* Release super blocks */
	for (i = 0; i < 2; i++) {
		if (zmd->sb[i].mblk) {
			dmz_free_mblock(zmd, zmd->sb[i].mblk);
			zmd->sb[i].mblk = NULL;
		}
	}

	/* Free cached blocks */
	while (!list_empty(&zmd->mblk_dirty_list)) {
		mblk = list_first_entry(&zmd->mblk_dirty_list,
					struct dmz_mblock, link);
		dmz_dev_warn(zmd->dev, "mblock %llu still in dirty list (ref %u)",
			     (u64)mblk->no, atomic_read(&mblk->ref));
		list_del_init(&mblk->link);
		rb_erase(&mblk->node, &zmd->mblk_rbtree);
		dmz_free_mblock(zmd, mblk);
	}

	while (!list_empty(&zmd->mblk_lru_list)) {
		mblk = list_first_entry(&zmd->mblk_lru_list,
					struct dmz_mblock, link);
		list_del_init(&mblk->link);
		rb_erase(&mblk->node, &zmd->mblk_rbtree);
		dmz_free_mblock(zmd, mblk);
	}

	/* Sanity checks: the mblock rbtree should now be empty */
	root = &zmd->mblk_rbtree;
	rbtree_postorder_for_each_entry_safe(mblk, next, root, node) {
		dmz_dev_warn(zmd->dev, "mblock %llu ref %u still in rbtree",
			     (u64)mblk->no, atomic_read(&mblk->ref));
		atomic_set(&mblk->ref, 0);
		dmz_free_mblock(zmd, mblk);
	}

	/* Free the zone descriptors */
	dmz_drop_zones(zmd);

	mutex_destroy(&zmd->mblk_flush_lock);
	mutex_destroy(&zmd->map_lock);
}

/*
 * Initialize the zoned metadata.
 */
int dmz_ctr_metadata(struct dmz_dev *dev, struct dmz_metadata **metadata)
{
	struct dmz_metadata *zmd;
	unsigned int i, zid;
	struct dm_zone *zone;
	int ret;

	zmd = kzalloc(sizeof(struct dmz_metadata), GFP_KERNEL);
	if (!zmd)
		return -ENOMEM;

	zmd->dev = dev;
	zmd->mblk_rbtree = RB_ROOT;
	init_rwsem(&zmd->mblk_sem);
	mutex_init(&zmd->mblk_flush_lock);
	spin_lock_init(&zmd->mblk_lock);
	INIT_LIST_HEAD(&zmd->mblk_lru_list);
	INIT_LIST_HEAD(&zmd->mblk_dirty_list);

	mutex_init(&zmd->map_lock);
	atomic_set(&zmd->unmap_nr_rnd, 0);
	INIT_LIST_HEAD(&zmd->unmap_rnd_list);
	INIT_LIST_HEAD(&zmd->map_rnd_list);

	atomic_set(&zmd->unmap_nr_seq, 0);
	INIT_LIST_HEAD(&zmd->unmap_seq_list);
	INIT_LIST_HEAD(&zmd->map_seq_list);

	atomic_set(&zmd->nr_reserved_seq_zones, 0);
	INIT_LIST_HEAD(&zmd->reserved_seq_zones_list);

	init_waitqueue_head(&zmd->free_wq);

	/* Initialize zone descriptors */
	ret = dmz_init_zones(zmd);
	if (ret)
		goto err;

	/* Get super block */
	ret = dmz_load_sb(zmd);
	if (ret)
		goto err;

	/* Set metadata zones starting from sb_zone */
	zid = dmz_id(zmd, zmd->sb_zone);
	for (i = 0; i < zmd->nr_meta_zones << 1; i++) {
		zone = dmz_get(zmd, zid + i);
		if (!dmz_is_rnd(zone))
			goto err;
		set_bit(DMZ_META, &zone->flags);
	}

	/* Load mapping table */
	ret = dmz_load_mapping(zmd);
	if (ret)
		goto err;

	/*
	 * Cache size boundaries: allow at least 2 super blocks, the chunk map
	 * blocks and enough blocks to be able to cache the bitmap blocks of
	 * up to 16 zones when idle (min_nr_mblks). Otherwise, if busy, allow
	 * the cache to add 512 more metadata blocks.
	 */
	zmd->min_nr_mblks = 2 + zmd->nr_map_blocks + zmd->zone_nr_bitmap_blocks * 16;
	zmd->max_nr_mblks = zmd->min_nr_mblks + 512;
	zmd->mblk_shrinker.count_objects = dmz_mblock_shrinker_count;
	zmd->mblk_shrinker.scan_objects = dmz_mblock_shrinker_scan;
	zmd->mblk_shrinker.seeks = DEFAULT_SEEKS;

	/* Metadata cache shrinker */
	ret = register_shrinker(&zmd->mblk_shrinker);
	if (ret) {
		dmz_dev_err(dev, "Register metadata cache shrinker failed");
		goto err;
	}

	dmz_dev_info(dev, "Host-%s zoned block device",
		     bdev_zoned_model(dev->bdev) == BLK_ZONED_HA ?
		     "aware" : "managed");
	dmz_dev_info(dev, "  %llu 512-byte logical sectors",
		     (u64)dev->capacity);
	dmz_dev_info(dev, "  %u zones of %llu 512-byte logical sectors",
		     dev->nr_zones, (u64)dev->zone_nr_sectors);
	dmz_dev_info(dev, "  %u metadata zones",
		     zmd->nr_meta_zones * 2);
	dmz_dev_info(dev, "  %u data zones for %u chunks",
		     zmd->nr_data_zones, zmd->nr_chunks);
	dmz_dev_info(dev, "    %u random zones (%u unmapped)",
		     zmd->nr_rnd, atomic_read(&zmd->unmap_nr_rnd));
	dmz_dev_info(dev, "    %u sequential zones (%u unmapped)",
		     zmd->nr_seq, atomic_read(&zmd->unmap_nr_seq));
	dmz_dev_info(dev, "  %u reserved sequential data zones",
		     zmd->nr_reserved_seq);

	dmz_dev_debug(dev, "Format:");
	dmz_dev_debug(dev, "%u metadata blocks per set (%u max cache)",
		      zmd->nr_meta_blocks, zmd->max_nr_mblks);
	dmz_dev_debug(dev, "  %u data zone mapping blocks",
		      zmd->nr_map_blocks);
	dmz_dev_debug(dev, "  %u bitmap blocks",
		      zmd->nr_bitmap_blocks);

	*metadata = zmd;

	return 0;
err:
	dmz_cleanup_metadata(zmd);
	kfree(zmd);
	*metadata = NULL;

	return ret;
}

/*
 * Cleanup the zoned metadata resources.
 */
void dmz_dtr_metadata(struct dmz_metadata *zmd)
{
	unregister_shrinker(&zmd->mblk_shrinker);
	dmz_cleanup_metadata(zmd);
	kfree(zmd);
}

/*
 * Check zone information on resume.
 */
int dmz_resume_metadata(struct dmz_metadata *zmd)
{
	struct dmz_dev *dev = zmd->dev;
	struct dm_zone *zone;
	sector_t wp_block;
	unsigned int i;
	int ret;

	/* Check zones */
	for (i = 0; i < dev->nr_zones; i++) {
		zone = dmz_get(zmd, i);
		if (!zone) {
			dmz_dev_err(dev, "Unable to get zone %u", i);
			return -EIO;
		}

		wp_block = zone->wp_block;

		ret = dmz_update_zone(zmd, zone);
		if (ret) {
			dmz_dev_err(dev, "Broken zone %u", i);
			return ret;
		}

		if (dmz_is_offline(zone)) {
			dmz_dev_warn(dev, "Zone %u is offline", i);
			continue;
		}

		/* Check write pointer */
		if (!dmz_is_seq(zone))
			zone->wp_block = 0;
		else if (zone->wp_block != wp_block) {
			dmz_dev_err(dev, "Zone %u: Invalid wp (%llu / %llu)",
				    i, (u64)zone->wp_block, (u64)wp_block);
			zone->wp_block = wp_block;
			dmz_invalidate_blocks(zmd, zone, zone->wp_block,
					      dev->zone_nr_blocks - zone->wp_block);
		}
	}

	return 0;
}