summaryrefslogtreecommitdiff
path: root/drivers/block/rbd.c
blob: a86841886accfb33aad16ce02bf6555497010584 (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
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
3215
3216
3217
3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244
3245
3246
3247
3248
3249
3250
3251
3252
3253
3254
3255
3256
3257
3258
3259
3260
3261
3262
3263
3264
3265
3266
3267
3268
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
3293
3294
3295
3296
3297
3298
3299
3300
3301
3302
3303
3304
3305
3306
3307
3308
3309
3310
3311
3312
3313
3314
3315
3316
3317
3318
3319
3320
3321
3322
3323
3324
3325
3326
3327
3328
3329
3330
3331
3332
3333
3334
3335
3336
3337
3338
3339
3340
3341
3342
3343
3344
3345
3346
3347
3348
3349
3350
3351
3352
3353
3354
3355
3356
3357
3358
3359
3360
3361
3362
3363
3364
3365
3366
3367
3368
3369
3370
3371
3372
3373
3374
3375
3376
3377
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
3406
3407
3408
3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
3421
3422
3423
3424
3425
3426
3427
3428
3429
3430
3431
3432
3433
3434
3435
3436
3437
3438
3439
3440
3441
3442
3443
3444
3445
3446
3447
3448
3449
3450
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463
3464
3465
3466
3467
3468
3469
3470
3471
3472
3473
3474
3475
3476
3477
3478
3479
3480
3481
3482
3483
3484
3485
3486
3487
3488
3489
3490
3491
3492
3493
3494
3495
3496
3497
3498
3499
3500
3501
3502
3503
3504
3505
3506
3507
3508
3509
3510
3511
3512
3513
3514
3515
3516
3517
3518
3519
3520
3521
3522
3523
3524
3525
3526
3527
3528
3529
3530
3531
3532
3533
3534
3535
3536
3537
3538
3539
3540
3541
3542
3543
3544
3545
3546
3547
3548
3549
3550
3551
3552
3553
3554
3555
3556
3557
3558
3559
3560
3561
3562
3563
3564
3565
3566
3567
3568
3569
3570
3571
3572
3573
3574
3575
3576
3577
3578
3579
3580
3581
3582
3583
3584
3585
3586
3587
3588
3589
3590
3591
3592
3593
3594
3595
3596
3597
3598
3599
3600
3601
3602
3603
3604
3605
3606
3607
3608
3609
3610
3611
3612
3613
3614
3615
3616
3617
3618
3619
3620
3621
3622
3623
3624
3625
3626
3627
3628
3629
3630
3631
3632
3633
3634
3635
3636
3637
3638
3639
3640
3641
3642
3643
3644
3645
3646
3647
3648
3649
3650
3651
3652
3653
3654
3655
3656
3657
3658
3659
3660
3661
3662
3663
3664
3665
3666
3667
3668
3669
3670
3671
3672
3673
3674
3675
3676
3677
3678
3679
3680
3681
3682
3683
3684
3685
3686
3687
3688
3689
3690
3691
3692
3693
3694
3695
3696
3697
3698
3699
3700
3701
3702
3703
3704
3705
3706
3707
3708
3709
3710
3711
3712
3713
3714
3715
3716
3717
3718
3719
3720
3721
3722
3723
3724
3725
3726
3727
3728
3729
3730
3731
3732
3733
3734
3735
3736
3737
3738
3739
3740
3741
3742
3743
3744
3745
3746
3747
3748
3749
3750
3751
3752
3753
3754
3755
3756
3757
3758
3759
3760
3761
3762
3763
3764
3765
3766
3767
3768
3769
3770
3771
3772
3773
3774
3775
3776
3777
3778
3779
3780
3781
3782
3783
3784
3785
3786
3787
3788
3789
3790
3791
3792
3793
3794
3795
3796
3797
3798
3799
3800
3801
3802
3803
3804
3805
3806
3807
3808
3809
3810
3811
3812
3813
3814
3815
3816
3817
3818
3819
3820
3821
3822
3823
3824
3825
3826
3827
3828
3829
3830
3831
3832
3833
3834
3835
3836
3837
3838
3839
3840
3841
3842
3843
3844
3845
3846
3847
3848
3849
3850
3851
3852
3853
3854
3855
3856
3857
3858
3859
3860
3861
3862
3863
3864
3865
3866
3867
3868
3869
3870
3871
3872
3873
3874
3875
3876
3877
3878
3879
3880
3881
3882
3883
3884
3885
3886
3887
3888
3889
3890
3891
3892
3893
3894
3895
3896
3897
3898
3899
3900
3901
3902
3903
3904
3905
3906
3907
3908
3909
3910
3911
3912
3913
3914
3915
3916
3917
3918
3919
3920
3921
3922
3923
3924
3925
3926
3927
3928
3929
3930
3931
3932
3933
3934
3935
3936
3937
3938
3939
3940
3941
3942
3943
3944
3945
3946
3947
3948
3949
3950
3951
3952
3953
3954
3955
3956
3957
3958
3959
3960
3961
3962
3963
3964
3965
3966
3967
3968
3969
3970
3971
3972
3973
3974
3975
3976
3977
3978
3979
3980
3981
3982
3983
3984
3985
3986
3987
3988
3989
3990
3991
3992
3993
3994
3995
3996
3997
3998
3999
4000
4001
4002
4003
4004
4005
4006
4007
4008
4009
4010
4011
4012
4013
4014
4015
4016
4017
4018
4019
4020
4021
4022
4023
4024
4025
4026
4027
4028
4029
4030
4031
4032
4033
4034
4035
4036
4037
4038
4039
4040
4041
4042
4043
4044
4045
4046
4047
4048
4049
4050
4051
4052
4053
4054
4055
4056
4057
4058
4059
4060
4061
4062
4063
4064
4065
4066
4067
4068
4069
4070
4071
4072
4073
4074
4075
4076
4077
4078
4079
4080
4081
4082
4083
4084
4085
4086
4087
4088
4089
4090
4091
4092
4093
4094
4095
4096
4097
4098
4099
4100
4101
4102
4103
4104
4105
4106
4107
4108
4109
4110
4111
4112
4113
4114
4115
4116
4117
4118
4119
4120
4121
4122
4123
4124
4125
4126
4127
4128
4129
4130
4131
4132
4133
4134
4135
4136
4137
4138
4139
4140
4141
4142
4143
4144
4145
4146
4147
4148
4149
4150
4151
4152
4153
4154
4155
4156
4157
4158
4159
4160
4161
4162
4163
4164
4165
4166
4167
4168
4169
4170
4171
4172
4173
4174
4175
4176
4177
4178
4179
4180
4181
4182
4183
4184
4185
4186
4187
4188
4189
4190
4191
4192
4193
4194
4195
4196
4197
4198
4199
4200
4201
4202
4203
4204
4205
4206
4207
4208
4209
4210
4211
4212
4213
4214
4215
4216
4217
4218
4219
4220
4221
4222
4223
4224
4225
4226
4227
4228
4229
4230
4231
4232
4233
4234
4235
4236
4237
4238
4239
4240
4241
4242
4243
4244
4245
4246
4247
4248
4249
4250
4251
4252
4253
4254
4255
4256
4257
4258
4259
4260
4261
4262
4263
4264
4265
4266
4267
4268
4269
4270
4271
4272
4273
4274
4275
4276
4277
4278
4279
4280
4281
4282
4283
4284
4285
4286
4287
4288
4289
4290
4291
4292
4293
4294
4295
4296
4297
4298
4299
4300
4301
4302
4303
4304
4305
4306
4307
4308
4309
4310
4311
4312
4313
4314
4315
4316
4317
4318
4319
4320
4321
4322
4323
4324
4325
4326
4327
4328
4329
4330
4331
4332
4333
4334
4335
4336
4337
4338
4339
4340
4341
4342
4343
4344
4345
4346
4347
4348
4349
4350
4351
4352
4353
4354
4355
4356
4357
4358
4359
4360
4361
4362
4363
4364
4365
4366
4367
4368
4369
4370
4371
4372
4373
4374
4375
4376
4377
4378
4379
4380
4381
4382
4383
4384
4385
4386
4387
4388
4389
4390
4391
4392
4393
4394
4395
4396
4397
4398
4399
4400
4401
4402
4403
4404
4405
4406
4407
4408
4409
4410
4411
4412
4413
4414
4415
4416
4417
4418
4419
4420
4421
4422
4423
4424
4425
4426
4427
4428
4429
4430
4431
4432
4433
4434
4435
4436
4437
4438
4439
4440
4441
4442
4443
4444
4445
4446
4447
4448
4449
4450
4451
4452
4453
4454
4455
4456
4457
4458
4459
4460
4461
4462
4463
4464
4465
4466
4467
4468
4469
4470
4471
4472
4473
4474
4475
4476
4477
4478
4479
4480
4481
4482
4483
4484
4485
4486
4487
4488
4489
4490
4491
4492
4493
4494
4495
4496
4497
4498
4499
4500
4501
4502
4503
4504
4505
4506
4507
4508
4509
4510
4511
4512
4513
4514
4515
4516
4517
4518
4519
4520
4521
4522
4523
4524
4525
4526
4527
4528
4529
4530
4531
4532
4533
4534
4535
4536
4537
4538
4539
4540
4541
4542
4543
4544
4545
4546
4547
4548
4549
4550
4551
4552
4553
4554
4555
4556
4557
4558
4559
4560
4561
4562
4563
4564
4565
4566
4567
4568
4569
4570
4571
4572
4573
4574
4575
4576
4577
4578
4579
4580
4581
4582
4583
4584
4585
4586
4587
4588
4589
4590
4591
4592
4593
4594
4595
4596
4597
4598
4599
4600
4601
4602
4603
4604
4605
4606
4607
4608
4609
4610
4611
4612
4613
4614
4615
4616
4617
4618
4619
4620
4621
4622
4623
4624
4625
4626
4627
4628
4629
4630
4631
4632
4633
4634
4635
4636
4637
4638
4639
4640
4641
4642
4643
4644
4645
4646
4647
4648
4649
4650
4651
4652
4653
4654
4655
4656
4657
4658
4659
4660
4661
4662
4663
4664
4665
4666
4667
4668
4669
4670
4671
4672
4673
4674
4675
4676
4677
4678
4679
4680
4681
4682
4683
4684
4685
4686
4687
4688
4689
4690
4691
4692
4693
4694
4695
4696
4697
4698
4699
4700
4701
4702
4703
4704
4705
4706
4707
4708
4709
4710
4711
4712
4713
4714
4715
4716
4717
4718
4719
4720
4721
4722
4723
4724
4725
4726
4727
4728
4729
4730
4731
4732
4733
4734
4735
4736
4737
4738
4739
4740
4741
4742
4743
4744
4745
4746
4747
4748
4749
4750
4751
4752
4753
4754
4755
4756
4757
4758
4759
4760
4761
4762
4763
4764
4765
4766
4767
4768
4769
4770
4771
4772
4773
4774
4775
4776
4777
4778
4779
4780
4781
4782
4783
4784
4785
4786
4787
4788
4789
4790
4791
4792
4793
4794
4795
4796
4797
4798
4799
4800
4801
4802
4803
4804
4805
4806
4807
4808
4809
4810
4811
4812
4813
4814
4815
4816
4817
4818
4819
4820
4821
4822
4823
4824
4825
4826
4827
4828
4829
4830
4831
4832
4833
4834
4835
4836
4837
4838
4839
4840
4841
4842
4843
4844
4845
4846
4847
4848
4849
4850
4851
4852
4853
4854
4855
4856
4857
4858
4859
4860
4861
4862
4863
4864
4865
4866
4867
4868
4869
4870
4871
4872
4873
4874
4875
4876
4877
4878
4879
4880
4881
4882
4883
4884
4885
4886
4887
4888
4889
4890
4891
4892
4893
4894
4895
4896
4897
4898
4899
4900
4901
4902
4903
4904
4905
4906
4907
4908
4909
4910
4911
4912
4913
4914
4915
4916
4917
4918
4919
4920
4921
4922
4923
4924
4925
4926
4927
4928
4929
4930
4931
4932
4933
4934
4935
4936
4937
4938
4939
4940
4941
4942
4943
4944
4945
4946
4947
4948
4949
4950
4951
4952
4953
4954
4955
4956
4957
4958
4959
4960
4961
4962
4963
4964
4965
4966
4967
4968
4969
4970
4971
4972
4973
4974
4975
4976
4977
4978
4979
4980
4981
4982
4983
4984
4985
4986
4987
4988
4989
4990
4991
4992
4993
4994
4995
4996
4997
4998
4999
5000
5001
5002
5003
5004
5005
5006
5007
5008
5009
5010
5011
5012
5013
5014
5015
5016
5017
5018
5019
5020
5021
5022
5023
5024
5025
5026
5027
5028
5029
5030
5031
5032
5033
5034
5035
5036
5037
5038
5039
5040
5041
5042
5043
5044
5045
5046
5047
5048
5049
5050
5051
5052
5053
5054
5055
5056
5057
5058
5059
5060
5061
5062
5063
5064
5065
5066
5067
5068
5069
5070
5071
5072
5073
5074
5075
5076
5077
5078
5079
5080
5081
5082
5083
5084
5085
5086
5087
5088
5089
5090
5091
5092
5093
5094
5095
5096
5097
5098
5099
5100
5101
5102
5103
5104
5105
5106
5107
5108
5109
5110
5111
5112
5113
5114
5115
5116
5117
5118
5119
5120
5121
5122
5123
5124
5125
5126
5127
5128
5129
5130
5131
5132
5133
5134
5135
5136
5137
5138
5139
5140
5141
5142
5143
5144
5145
5146
5147
5148
5149
5150
5151
5152
5153
5154
5155
5156
5157
5158
5159
5160
5161
5162
5163
5164
5165
5166
5167
5168
5169
5170
5171
5172
5173
5174
5175
5176
5177
5178
5179
5180
5181
5182
5183
5184
5185
5186
5187
5188
5189
5190
5191
5192
5193
5194
5195
5196
5197
5198
5199
5200
5201
5202
5203
5204
5205
5206
5207
5208
5209
5210
5211
5212
5213
5214
5215
5216
5217
5218
5219
5220
5221
5222
5223
5224
5225
5226
5227
5228
5229
5230
5231
5232
5233
5234
5235
5236
5237
5238
5239
5240
5241
5242
5243
5244
5245
5246
5247
5248
5249
5250
5251
5252
5253
5254
5255
5256
5257
5258
5259
5260
5261
5262
5263
5264
5265
5266
5267
5268
5269
5270
5271
5272
5273
5274
5275
5276
5277
5278
5279
5280
5281
5282
5283
5284
5285
5286
5287
5288
5289
5290
5291
5292
5293
5294
5295
5296
5297
5298
5299
5300
5301
5302
5303
5304
5305
5306
5307
5308
5309
5310
5311
5312
5313
5314
5315
5316
5317
5318
5319
5320
5321
5322
5323
5324
5325
5326
5327
5328
5329
5330
5331
5332
5333
5334
5335
5336
5337
5338
5339
5340
5341
5342
5343
5344
5345
5346
5347

/*
   rbd.c -- Export ceph rados objects as a Linux block device


   based on drivers/block/osdblk.c:

   Copyright 2009 Red Hat, Inc.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; see the file COPYING.  If not, write to
   the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.



   For usage instructions, please refer to:

                 Documentation/ABI/testing/sysfs-bus-rbd

 */

#include <linux/ceph/libceph.h>
#include <linux/ceph/osd_client.h>
#include <linux/ceph/mon_client.h>
#include <linux/ceph/decode.h>
#include <linux/parser.h>
#include <linux/bsearch.h>

#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/blkdev.h>
#include <linux/slab.h>

#include "rbd_types.h"

#define RBD_DEBUG	/* Activate rbd_assert() calls */

/*
 * The basic unit of block I/O is a sector.  It is interpreted in a
 * number of contexts in Linux (blk, bio, genhd), but the default is
 * universally 512 bytes.  These symbols are just slightly more
 * meaningful than the bare numbers they represent.
 */
#define	SECTOR_SHIFT	9
#define	SECTOR_SIZE	(1ULL << SECTOR_SHIFT)

/*
 * Increment the given counter and return its updated value.
 * If the counter is already 0 it will not be incremented.
 * If the counter is already at its maximum value returns
 * -EINVAL without updating it.
 */
static int atomic_inc_return_safe(atomic_t *v)
{
	unsigned int counter;

	counter = (unsigned int)__atomic_add_unless(v, 1, 0);
	if (counter <= (unsigned int)INT_MAX)
		return (int)counter;

	atomic_dec(v);

	return -EINVAL;
}

/* Decrement the counter.  Return the resulting value, or -EINVAL */
static int atomic_dec_return_safe(atomic_t *v)
{
	int counter;

	counter = atomic_dec_return(v);
	if (counter >= 0)
		return counter;

	atomic_inc(v);

	return -EINVAL;
}

#define RBD_DRV_NAME "rbd"
#define RBD_DRV_NAME_LONG "rbd (rados block device)"

#define RBD_MINORS_PER_MAJOR	256		/* max minors per blkdev */

#define RBD_SNAP_DEV_NAME_PREFIX	"snap_"
#define RBD_MAX_SNAP_NAME_LEN	\
			(NAME_MAX - (sizeof (RBD_SNAP_DEV_NAME_PREFIX) - 1))

#define RBD_MAX_SNAP_COUNT	510	/* allows max snapc to fit in 4KB */

#define RBD_SNAP_HEAD_NAME	"-"

#define	BAD_SNAP_INDEX	U32_MAX		/* invalid index into snap array */

/* This allows a single page to hold an image name sent by OSD */
#define RBD_IMAGE_NAME_LEN_MAX	(PAGE_SIZE - sizeof (__le32) - 1)
#define RBD_IMAGE_ID_LEN_MAX	64

#define RBD_OBJ_PREFIX_LEN_MAX	64

/* Feature bits */

#define RBD_FEATURE_LAYERING	(1<<0)
#define RBD_FEATURE_STRIPINGV2	(1<<1)
#define RBD_FEATURES_ALL \
	    (RBD_FEATURE_LAYERING | RBD_FEATURE_STRIPINGV2)

/* Features supported by this (client software) implementation. */

#define RBD_FEATURES_SUPPORTED	(RBD_FEATURES_ALL)

/*
 * An RBD device name will be "rbd#", where the "rbd" comes from
 * RBD_DRV_NAME above, and # is a unique integer identifier.
 * MAX_INT_FORMAT_WIDTH is used in ensuring DEV_NAME_LEN is big
 * enough to hold all possible device names.
 */
#define DEV_NAME_LEN		32
#define MAX_INT_FORMAT_WIDTH	((5 * sizeof (int)) / 2 + 1)

/*
 * block device image metadata (in-memory version)
 */
struct rbd_image_header {
	/* These six fields never change for a given rbd image */
	char *object_prefix;
	__u8 obj_order;
	__u8 crypt_type;
	__u8 comp_type;
	u64 stripe_unit;
	u64 stripe_count;
	u64 features;		/* Might be changeable someday? */

	/* The remaining fields need to be updated occasionally */
	u64 image_size;
	struct ceph_snap_context *snapc;
	char *snap_names;	/* format 1 only */
	u64 *snap_sizes;	/* format 1 only */
};

/*
 * An rbd image specification.
 *
 * The tuple (pool_id, image_id, snap_id) is sufficient to uniquely
 * identify an image.  Each rbd_dev structure includes a pointer to
 * an rbd_spec structure that encapsulates this identity.
 *
 * Each of the id's in an rbd_spec has an associated name.  For a
 * user-mapped image, the names are supplied and the id's associated
 * with them are looked up.  For a layered image, a parent image is
 * defined by the tuple, and the names are looked up.
 *
 * An rbd_dev structure contains a parent_spec pointer which is
 * non-null if the image it represents is a child in a layered
 * image.  This pointer will refer to the rbd_spec structure used
 * by the parent rbd_dev for its own identity (i.e., the structure
 * is shared between the parent and child).
 *
 * Since these structures are populated once, during the discovery
 * phase of image construction, they are effectively immutable so
 * we make no effort to synchronize access to them.
 *
 * Note that code herein does not assume the image name is known (it
 * could be a null pointer).
 */
struct rbd_spec {
	u64		pool_id;
	const char	*pool_name;

	const char	*image_id;
	const char	*image_name;

	u64		snap_id;
	const char	*snap_name;

	struct kref	kref;
};

/*
 * an instance of the client.  multiple devices may share an rbd client.
 */
struct rbd_client {
	struct ceph_client	*client;
	struct kref		kref;
	struct list_head	node;
};

struct rbd_img_request;
typedef void (*rbd_img_callback_t)(struct rbd_img_request *);

#define	BAD_WHICH	U32_MAX		/* Good which or bad which, which? */

struct rbd_obj_request;
typedef void (*rbd_obj_callback_t)(struct rbd_obj_request *);

enum obj_request_type {
	OBJ_REQUEST_NODATA, OBJ_REQUEST_BIO, OBJ_REQUEST_PAGES
};

enum obj_req_flags {
	OBJ_REQ_DONE,		/* completion flag: not done = 0, done = 1 */
	OBJ_REQ_IMG_DATA,	/* object usage: standalone = 0, image = 1 */
	OBJ_REQ_KNOWN,		/* EXISTS flag valid: no = 0, yes = 1 */
	OBJ_REQ_EXISTS,		/* target exists: no = 0, yes = 1 */
};

struct rbd_obj_request {
	const char		*object_name;
	u64			offset;		/* object start byte */
	u64			length;		/* bytes from offset */
	unsigned long		flags;

	/*
	 * An object request associated with an image will have its
	 * img_data flag set; a standalone object request will not.
	 *
	 * A standalone object request will have which == BAD_WHICH
	 * and a null obj_request pointer.
	 *
	 * An object request initiated in support of a layered image
	 * object (to check for its existence before a write) will
	 * have which == BAD_WHICH and a non-null obj_request pointer.
	 *
	 * Finally, an object request for rbd image data will have
	 * which != BAD_WHICH, and will have a non-null img_request
	 * pointer.  The value of which will be in the range
	 * 0..(img_request->obj_request_count-1).
	 */
	union {
		struct rbd_obj_request	*obj_request;	/* STAT op */
		struct {
			struct rbd_img_request	*img_request;
			u64			img_offset;
			/* links for img_request->obj_requests list */
			struct list_head	links;
		};
	};
	u32			which;		/* posn image request list */

	enum obj_request_type	type;
	union {
		struct bio	*bio_list;
		struct {
			struct page	**pages;
			u32		page_count;
		};
	};
	struct page		**copyup_pages;
	u32			copyup_page_count;

	struct ceph_osd_request	*osd_req;

	u64			xferred;	/* bytes transferred */
	int			result;

	rbd_obj_callback_t	callback;
	struct completion	completion;

	struct kref		kref;
};

enum img_req_flags {
	IMG_REQ_WRITE,		/* I/O direction: read = 0, write = 1 */
	IMG_REQ_CHILD,		/* initiator: block = 0, child image = 1 */
	IMG_REQ_LAYERED,	/* ENOENT handling: normal = 0, layered = 1 */
};

struct rbd_img_request {
	struct rbd_device	*rbd_dev;
	u64			offset;	/* starting image byte offset */
	u64			length;	/* byte count from offset */
	unsigned long		flags;
	union {
		u64			snap_id;	/* for reads */
		struct ceph_snap_context *snapc;	/* for writes */
	};
	union {
		struct request		*rq;		/* block request */
		struct rbd_obj_request	*obj_request;	/* obj req initiator */
	};
	struct page		**copyup_pages;
	u32			copyup_page_count;
	spinlock_t		completion_lock;/* protects next_completion */
	u32			next_completion;
	rbd_img_callback_t	callback;
	u64			xferred;/* aggregate bytes transferred */
	int			result;	/* first nonzero obj_request result */

	u32			obj_request_count;
	struct list_head	obj_requests;	/* rbd_obj_request structs */

	struct kref		kref;
};

#define for_each_obj_request(ireq, oreq) \
	list_for_each_entry(oreq, &(ireq)->obj_requests, links)
#define for_each_obj_request_from(ireq, oreq) \
	list_for_each_entry_from(oreq, &(ireq)->obj_requests, links)
#define for_each_obj_request_safe(ireq, oreq, n) \
	list_for_each_entry_safe_reverse(oreq, n, &(ireq)->obj_requests, links)

struct rbd_mapping {
	u64                     size;
	u64                     features;
	bool			read_only;
};

/*
 * a single device
 */
struct rbd_device {
	int			dev_id;		/* blkdev unique id */

	int			major;		/* blkdev assigned major */
	struct gendisk		*disk;		/* blkdev's gendisk and rq */

	u32			image_format;	/* Either 1 or 2 */
	struct rbd_client	*rbd_client;

	char			name[DEV_NAME_LEN]; /* blkdev name, e.g. rbd3 */

	spinlock_t		lock;		/* queue, flags, open_count */

	struct rbd_image_header	header;
	unsigned long		flags;		/* possibly lock protected */
	struct rbd_spec		*spec;

	char			*header_name;

	struct ceph_file_layout	layout;

	struct ceph_osd_event   *watch_event;
	struct rbd_obj_request	*watch_request;

	struct rbd_spec		*parent_spec;
	u64			parent_overlap;
	atomic_t		parent_ref;
	struct rbd_device	*parent;

	/* protects updating the header */
	struct rw_semaphore     header_rwsem;

	struct rbd_mapping	mapping;

	struct list_head	node;

	/* sysfs related */
	struct device		dev;
	unsigned long		open_count;	/* protected by lock */
};

/*
 * Flag bits for rbd_dev->flags.  If atomicity is required,
 * rbd_dev->lock is used to protect access.
 *
 * Currently, only the "removing" flag (which is coupled with the
 * "open_count" field) requires atomic access.
 */
enum rbd_dev_flags {
	RBD_DEV_FLAG_EXISTS,	/* mapped snapshot has not been deleted */
	RBD_DEV_FLAG_REMOVING,	/* this mapping is being removed */
};

static DEFINE_MUTEX(client_mutex);	/* Serialize client creation */

static LIST_HEAD(rbd_dev_list);    /* devices */
static DEFINE_SPINLOCK(rbd_dev_list_lock);

static LIST_HEAD(rbd_client_list);		/* clients */
static DEFINE_SPINLOCK(rbd_client_list_lock);

/* Slab caches for frequently-allocated structures */

static struct kmem_cache	*rbd_img_request_cache;
static struct kmem_cache	*rbd_obj_request_cache;
static struct kmem_cache	*rbd_segment_name_cache;

static int rbd_img_request_submit(struct rbd_img_request *img_request);

static void rbd_dev_device_release(struct device *dev);

static ssize_t rbd_add(struct bus_type *bus, const char *buf,
		       size_t count);
static ssize_t rbd_remove(struct bus_type *bus, const char *buf,
			  size_t count);
static int rbd_dev_image_probe(struct rbd_device *rbd_dev, bool mapping);
static void rbd_spec_put(struct rbd_spec *spec);

static BUS_ATTR(add, S_IWUSR, NULL, rbd_add);
static BUS_ATTR(remove, S_IWUSR, NULL, rbd_remove);

static struct attribute *rbd_bus_attrs[] = {
	&bus_attr_add.attr,
	&bus_attr_remove.attr,
	NULL,
};
ATTRIBUTE_GROUPS(rbd_bus);

static struct bus_type rbd_bus_type = {
	.name		= "rbd",
	.bus_groups	= rbd_bus_groups,
};

static void rbd_root_dev_release(struct device *dev)
{
}

static struct device rbd_root_dev = {
	.init_name =    "rbd",
	.release =      rbd_root_dev_release,
};

static __printf(2, 3)
void rbd_warn(struct rbd_device *rbd_dev, const char *fmt, ...)
{
	struct va_format vaf;
	va_list args;

	va_start(args, fmt);
	vaf.fmt = fmt;
	vaf.va = &args;

	if (!rbd_dev)
		printk(KERN_WARNING "%s: %pV\n", RBD_DRV_NAME, &vaf);
	else if (rbd_dev->disk)
		printk(KERN_WARNING "%s: %s: %pV\n",
			RBD_DRV_NAME, rbd_dev->disk->disk_name, &vaf);
	else if (rbd_dev->spec && rbd_dev->spec->image_name)
		printk(KERN_WARNING "%s: image %s: %pV\n",
			RBD_DRV_NAME, rbd_dev->spec->image_name, &vaf);
	else if (rbd_dev->spec && rbd_dev->spec->image_id)
		printk(KERN_WARNING "%s: id %s: %pV\n",
			RBD_DRV_NAME, rbd_dev->spec->image_id, &vaf);
	else	/* punt */
		printk(KERN_WARNING "%s: rbd_dev %p: %pV\n",
			RBD_DRV_NAME, rbd_dev, &vaf);
	va_end(args);
}

#ifdef RBD_DEBUG
#define rbd_assert(expr)						\
		if (unlikely(!(expr))) {				\
			printk(KERN_ERR "\nAssertion failure in %s() "	\
						"at line %d:\n\n"	\
					"\trbd_assert(%s);\n\n",	\
					__func__, __LINE__, #expr);	\
			BUG();						\
		}
#else /* !RBD_DEBUG */
#  define rbd_assert(expr)	((void) 0)
#endif /* !RBD_DEBUG */

static int rbd_img_obj_request_submit(struct rbd_obj_request *obj_request);
static void rbd_img_parent_read(struct rbd_obj_request *obj_request);
static void rbd_dev_remove_parent(struct rbd_device *rbd_dev);

static int rbd_dev_refresh(struct rbd_device *rbd_dev);
static int rbd_dev_v2_header_onetime(struct rbd_device *rbd_dev);
static int rbd_dev_v2_header_info(struct rbd_device *rbd_dev);
static const char *rbd_dev_v2_snap_name(struct rbd_device *rbd_dev,
					u64 snap_id);
static int _rbd_dev_v2_snap_size(struct rbd_device *rbd_dev, u64 snap_id,
				u8 *order, u64 *snap_size);
static int _rbd_dev_v2_snap_features(struct rbd_device *rbd_dev, u64 snap_id,
		u64 *snap_features);
static u64 rbd_snap_id_by_name(struct rbd_device *rbd_dev, const char *name);

static int rbd_open(struct block_device *bdev, fmode_t mode)
{
	struct rbd_device *rbd_dev = bdev->bd_disk->private_data;
	bool removing = false;

	if ((mode & FMODE_WRITE) && rbd_dev->mapping.read_only)
		return -EROFS;

	spin_lock_irq(&rbd_dev->lock);
	if (test_bit(RBD_DEV_FLAG_REMOVING, &rbd_dev->flags))
		removing = true;
	else
		rbd_dev->open_count++;
	spin_unlock_irq(&rbd_dev->lock);
	if (removing)
		return -ENOENT;

	(void) get_device(&rbd_dev->dev);
	set_device_ro(bdev, rbd_dev->mapping.read_only);

	return 0;
}

static void rbd_release(struct gendisk *disk, fmode_t mode)
{
	struct rbd_device *rbd_dev = disk->private_data;
	unsigned long open_count_before;

	spin_lock_irq(&rbd_dev->lock);
	open_count_before = rbd_dev->open_count--;
	spin_unlock_irq(&rbd_dev->lock);
	rbd_assert(open_count_before > 0);

	put_device(&rbd_dev->dev);
}

static const struct block_device_operations rbd_bd_ops = {
	.owner			= THIS_MODULE,
	.open			= rbd_open,
	.release		= rbd_release,
};

/*
 * Initialize an rbd client instance.  Success or not, this function
 * consumes ceph_opts.  Caller holds client_mutex.
 */
static struct rbd_client *rbd_client_create(struct ceph_options *ceph_opts)
{
	struct rbd_client *rbdc;
	int ret = -ENOMEM;

	dout("%s:\n", __func__);
	rbdc = kmalloc(sizeof(struct rbd_client), GFP_KERNEL);
	if (!rbdc)
		goto out_opt;

	kref_init(&rbdc->kref);
	INIT_LIST_HEAD(&rbdc->node);

	rbdc->client = ceph_create_client(ceph_opts, rbdc, 0, 0);
	if (IS_ERR(rbdc->client))
		goto out_rbdc;
	ceph_opts = NULL; /* Now rbdc->client is responsible for ceph_opts */

	ret = ceph_open_session(rbdc->client);
	if (ret < 0)
		goto out_client;

	spin_lock(&rbd_client_list_lock);
	list_add_tail(&rbdc->node, &rbd_client_list);
	spin_unlock(&rbd_client_list_lock);

	dout("%s: rbdc %p\n", __func__, rbdc);

	return rbdc;
out_client:
	ceph_destroy_client(rbdc->client);
out_rbdc:
	kfree(rbdc);
out_opt:
	if (ceph_opts)
		ceph_destroy_options(ceph_opts);
	dout("%s: error %d\n", __func__, ret);

	return ERR_PTR(ret);
}

static struct rbd_client *__rbd_get_client(struct rbd_client *rbdc)
{
	kref_get(&rbdc->kref);

	return rbdc;
}

/*
 * Find a ceph client with specific addr and configuration.  If
 * found, bump its reference count.
 */
static struct rbd_client *rbd_client_find(struct ceph_options *ceph_opts)
{
	struct rbd_client *client_node;
	bool found = false;

	if (ceph_opts->flags & CEPH_OPT_NOSHARE)
		return NULL;

	spin_lock(&rbd_client_list_lock);
	list_for_each_entry(client_node, &rbd_client_list, node) {
		if (!ceph_compare_options(ceph_opts, client_node->client)) {
			__rbd_get_client(client_node);

			found = true;
			break;
		}
	}
	spin_unlock(&rbd_client_list_lock);

	return found ? client_node : NULL;
}

/*
 * mount options
 */
enum {
	Opt_last_int,
	/* int args above */
	Opt_last_string,
	/* string args above */
	Opt_read_only,
	Opt_read_write,
	/* Boolean args above */
	Opt_last_bool,
};

static match_table_t rbd_opts_tokens = {
	/* int args above */
	/* string args above */
	{Opt_read_only, "read_only"},
	{Opt_read_only, "ro"},		/* Alternate spelling */
	{Opt_read_write, "read_write"},
	{Opt_read_write, "rw"},		/* Alternate spelling */
	/* Boolean args above */
	{-1, NULL}
};

struct rbd_options {
	bool	read_only;
};

#define RBD_READ_ONLY_DEFAULT	false

static int parse_rbd_opts_token(char *c, void *private)
{
	struct rbd_options *rbd_opts = private;
	substring_t argstr[MAX_OPT_ARGS];
	int token, intval, ret;

	token = match_token(c, rbd_opts_tokens, argstr);
	if (token < 0)
		return -EINVAL;

	if (token < Opt_last_int) {
		ret = match_int(&argstr[0], &intval);
		if (ret < 0) {
			pr_err("bad mount option arg (not int) "
			       "at '%s'\n", c);
			return ret;
		}
		dout("got int token %d val %d\n", token, intval);
	} else if (token > Opt_last_int && token < Opt_last_string) {
		dout("got string token %d val %s\n", token,
		     argstr[0].from);
	} else if (token > Opt_last_string && token < Opt_last_bool) {
		dout("got Boolean token %d\n", token);
	} else {
		dout("got token %d\n", token);
	}

	switch (token) {
	case Opt_read_only:
		rbd_opts->read_only = true;
		break;
	case Opt_read_write:
		rbd_opts->read_only = false;
		break;
	default:
		rbd_assert(false);
		break;
	}
	return 0;
}

/*
 * Get a ceph client with specific addr and configuration, if one does
 * not exist create it.  Either way, ceph_opts is consumed by this
 * function.
 */
static struct rbd_client *rbd_get_client(struct ceph_options *ceph_opts)
{
	struct rbd_client *rbdc;

	mutex_lock_nested(&client_mutex, SINGLE_DEPTH_NESTING);
	rbdc = rbd_client_find(ceph_opts);
	if (rbdc)	/* using an existing client */
		ceph_destroy_options(ceph_opts);
	else
		rbdc = rbd_client_create(ceph_opts);
	mutex_unlock(&client_mutex);

	return rbdc;
}

/*
 * Destroy ceph client
 *
 * Caller must hold rbd_client_list_lock.
 */
static void rbd_client_release(struct kref *kref)
{
	struct rbd_client *rbdc = container_of(kref, struct rbd_client, kref);

	dout("%s: rbdc %p\n", __func__, rbdc);
	spin_lock(&rbd_client_list_lock);
	list_del(&rbdc->node);
	spin_unlock(&rbd_client_list_lock);

	ceph_destroy_client(rbdc->client);
	kfree(rbdc);
}

/*
 * Drop reference to ceph client node. If it's not referenced anymore, release
 * it.
 */
static void rbd_put_client(struct rbd_client *rbdc)
{
	if (rbdc)
		kref_put(&rbdc->kref, rbd_client_release);
}

static bool rbd_image_format_valid(u32 image_format)
{
	return image_format == 1 || image_format == 2;
}

static bool rbd_dev_ondisk_valid(struct rbd_image_header_ondisk *ondisk)
{
	size_t size;
	u32 snap_count;

	/* The header has to start with the magic rbd header text */
	if (memcmp(&ondisk->text, RBD_HEADER_TEXT, sizeof (RBD_HEADER_TEXT)))
		return false;

	/* The bio layer requires at least sector-sized I/O */

	if (ondisk->options.order < SECTOR_SHIFT)
		return false;

	/* If we use u64 in a few spots we may be able to loosen this */

	if (ondisk->options.order > 8 * sizeof (int) - 1)
		return false;

	/*
	 * The size of a snapshot header has to fit in a size_t, and
	 * that limits the number of snapshots.
	 */
	snap_count = le32_to_cpu(ondisk->snap_count);
	size = SIZE_MAX - sizeof (struct ceph_snap_context);
	if (snap_count > size / sizeof (__le64))
		return false;

	/*
	 * Not only that, but the size of the entire the snapshot
	 * header must also be representable in a size_t.
	 */
	size -= snap_count * sizeof (__le64);
	if ((u64) size < le64_to_cpu(ondisk->snap_names_len))
		return false;

	return true;
}

/*
 * Fill an rbd image header with information from the given format 1
 * on-disk header.
 */
static int rbd_header_from_disk(struct rbd_device *rbd_dev,
				 struct rbd_image_header_ondisk *ondisk)
{
	struct rbd_image_header *header = &rbd_dev->header;
	bool first_time = header->object_prefix == NULL;
	struct ceph_snap_context *snapc;
	char *object_prefix = NULL;
	char *snap_names = NULL;
	u64 *snap_sizes = NULL;
	u32 snap_count;
	size_t size;
	int ret = -ENOMEM;
	u32 i;

	/* Allocate this now to avoid having to handle failure below */

	if (first_time) {
		size_t len;

		len = strnlen(ondisk->object_prefix,
				sizeof (ondisk->object_prefix));
		object_prefix = kmalloc(len + 1, GFP_KERNEL);
		if (!object_prefix)
			return -ENOMEM;
		memcpy(object_prefix, ondisk->object_prefix, len);
		object_prefix[len] = '\0';
	}

	/* Allocate the snapshot context and fill it in */

	snap_count = le32_to_cpu(ondisk->snap_count);
	snapc = ceph_create_snap_context(snap_count, GFP_KERNEL);
	if (!snapc)
		goto out_err;
	snapc->seq = le64_to_cpu(ondisk->snap_seq);
	if (snap_count) {
		struct rbd_image_snap_ondisk *snaps;
		u64 snap_names_len = le64_to_cpu(ondisk->snap_names_len);

		/* We'll keep a copy of the snapshot names... */

		if (snap_names_len > (u64)SIZE_MAX)
			goto out_2big;
		snap_names = kmalloc(snap_names_len, GFP_KERNEL);
		if (!snap_names)
			goto out_err;

		/* ...as well as the array of their sizes. */

		size = snap_count * sizeof (*header->snap_sizes);
		snap_sizes = kmalloc(size, GFP_KERNEL);
		if (!snap_sizes)
			goto out_err;

		/*
		 * Copy the names, and fill in each snapshot's id
		 * and size.
		 *
		 * Note that rbd_dev_v1_header_info() guarantees the
		 * ondisk buffer we're working with has
		 * snap_names_len bytes beyond the end of the
		 * snapshot id array, this memcpy() is safe.
		 */
		memcpy(snap_names, &ondisk->snaps[snap_count], snap_names_len);
		snaps = ondisk->snaps;
		for (i = 0; i < snap_count; i++) {
			snapc->snaps[i] = le64_to_cpu(snaps[i].id);
			snap_sizes[i] = le64_to_cpu(snaps[i].image_size);
		}
	}

	/* We won't fail any more, fill in the header */

	if (first_time) {
		header->object_prefix = object_prefix;
		header->obj_order = ondisk->options.order;
		header->crypt_type = ondisk->options.crypt_type;
		header->comp_type = ondisk->options.comp_type;
		/* The rest aren't used for format 1 images */
		header->stripe_unit = 0;
		header->stripe_count = 0;
		header->features = 0;
	} else {
		ceph_put_snap_context(header->snapc);
		kfree(header->snap_names);
		kfree(header->snap_sizes);
	}

	/* The remaining fields always get updated (when we refresh) */

	header->image_size = le64_to_cpu(ondisk->image_size);
	header->snapc = snapc;
	header->snap_names = snap_names;
	header->snap_sizes = snap_sizes;

	/* Make sure mapping size is consistent with header info */

	if (rbd_dev->spec->snap_id == CEPH_NOSNAP || first_time)
		if (rbd_dev->mapping.size != header->image_size)
			rbd_dev->mapping.size = header->image_size;

	return 0;
out_2big:
	ret = -EIO;
out_err:
	kfree(snap_sizes);
	kfree(snap_names);
	ceph_put_snap_context(snapc);
	kfree(object_prefix);

	return ret;
}

static const char *_rbd_dev_v1_snap_name(struct rbd_device *rbd_dev, u32 which)
{
	const char *snap_name;

	rbd_assert(which < rbd_dev->header.snapc->num_snaps);

	/* Skip over names until we find the one we are looking for */

	snap_name = rbd_dev->header.snap_names;
	while (which--)
		snap_name += strlen(snap_name) + 1;

	return kstrdup(snap_name, GFP_KERNEL);
}

/*
 * Snapshot id comparison function for use with qsort()/bsearch().
 * Note that result is for snapshots in *descending* order.
 */
static int snapid_compare_reverse(const void *s1, const void *s2)
{
	u64 snap_id1 = *(u64 *)s1;
	u64 snap_id2 = *(u64 *)s2;

	if (snap_id1 < snap_id2)
		return 1;
	return snap_id1 == snap_id2 ? 0 : -1;
}

/*
 * Search a snapshot context to see if the given snapshot id is
 * present.
 *
 * Returns the position of the snapshot id in the array if it's found,
 * or BAD_SNAP_INDEX otherwise.
 *
 * Note: The snapshot array is in kept sorted (by the osd) in
 * reverse order, highest snapshot id first.
 */
static u32 rbd_dev_snap_index(struct rbd_device *rbd_dev, u64 snap_id)
{
	struct ceph_snap_context *snapc = rbd_dev->header.snapc;
	u64 *found;

	found = bsearch(&snap_id, &snapc->snaps, snapc->num_snaps,
				sizeof (snap_id), snapid_compare_reverse);

	return found ? (u32)(found - &snapc->snaps[0]) : BAD_SNAP_INDEX;
}

static const char *rbd_dev_v1_snap_name(struct rbd_device *rbd_dev,
					u64 snap_id)
{
	u32 which;
	const char *snap_name;

	which = rbd_dev_snap_index(rbd_dev, snap_id);
	if (which == BAD_SNAP_INDEX)
		return ERR_PTR(-ENOENT);

	snap_name = _rbd_dev_v1_snap_name(rbd_dev, which);
	return snap_name ? snap_name : ERR_PTR(-ENOMEM);
}

static const char *rbd_snap_name(struct rbd_device *rbd_dev, u64 snap_id)
{
	if (snap_id == CEPH_NOSNAP)
		return RBD_SNAP_HEAD_NAME;

	rbd_assert(rbd_image_format_valid(rbd_dev->image_format));
	if (rbd_dev->image_format == 1)
		return rbd_dev_v1_snap_name(rbd_dev, snap_id);

	return rbd_dev_v2_snap_name(rbd_dev, snap_id);
}

static int rbd_snap_size(struct rbd_device *rbd_dev, u64 snap_id,
				u64 *snap_size)
{
	rbd_assert(rbd_image_format_valid(rbd_dev->image_format));
	if (snap_id == CEPH_NOSNAP) {
		*snap_size = rbd_dev->header.image_size;
	} else if (rbd_dev->image_format == 1) {
		u32 which;

		which = rbd_dev_snap_index(rbd_dev, snap_id);
		if (which == BAD_SNAP_INDEX)
			return -ENOENT;

		*snap_size = rbd_dev->header.snap_sizes[which];
	} else {
		u64 size = 0;
		int ret;

		ret = _rbd_dev_v2_snap_size(rbd_dev, snap_id, NULL, &size);
		if (ret)
			return ret;

		*snap_size = size;
	}
	return 0;
}

static int rbd_snap_features(struct rbd_device *rbd_dev, u64 snap_id,
			u64 *snap_features)
{
	rbd_assert(rbd_image_format_valid(rbd_dev->image_format));
	if (snap_id == CEPH_NOSNAP) {
		*snap_features = rbd_dev->header.features;
	} else if (rbd_dev->image_format == 1) {
		*snap_features = 0;	/* No features for format 1 */
	} else {
		u64 features = 0;
		int ret;

		ret = _rbd_dev_v2_snap_features(rbd_dev, snap_id, &features);
		if (ret)
			return ret;

		*snap_features = features;
	}
	return 0;
}

static int rbd_dev_mapping_set(struct rbd_device *rbd_dev)
{
	u64 snap_id = rbd_dev->spec->snap_id;
	u64 size = 0;
	u64 features = 0;
	int ret;

	ret = rbd_snap_size(rbd_dev, snap_id, &size);
	if (ret)
		return ret;
	ret = rbd_snap_features(rbd_dev, snap_id, &features);
	if (ret)
		return ret;

	rbd_dev->mapping.size = size;
	rbd_dev->mapping.features = features;

	return 0;
}

static void rbd_dev_mapping_clear(struct rbd_device *rbd_dev)
{
	rbd_dev->mapping.size = 0;
	rbd_dev->mapping.features = 0;
}

static const char *rbd_segment_name(struct rbd_device *rbd_dev, u64 offset)
{
	char *name;
	u64 segment;
	int ret;
	char *name_format;

	name = kmem_cache_alloc(rbd_segment_name_cache, GFP_NOIO);
	if (!name)
		return NULL;
	segment = offset >> rbd_dev->header.obj_order;
	name_format = "%s.%012llx";
	if (rbd_dev->image_format == 2)
		name_format = "%s.%016llx";
	ret = snprintf(name, MAX_OBJ_NAME_SIZE + 1, name_format,
			rbd_dev->header.object_prefix, segment);
	if (ret < 0 || ret > MAX_OBJ_NAME_SIZE) {
		pr_err("error formatting segment name for #%llu (%d)\n",
			segment, ret);
		kfree(name);
		name = NULL;
	}

	return name;
}

static void rbd_segment_name_free(const char *name)
{
	/* The explicit cast here is needed to drop the const qualifier */

	kmem_cache_free(rbd_segment_name_cache, (void *)name);
}

static u64 rbd_segment_offset(struct rbd_device *rbd_dev, u64 offset)
{
	u64 segment_size = (u64) 1 << rbd_dev->header.obj_order;

	return offset & (segment_size - 1);
}

static u64 rbd_segment_length(struct rbd_device *rbd_dev,
				u64 offset, u64 length)
{
	u64 segment_size = (u64) 1 << rbd_dev->header.obj_order;

	offset &= segment_size - 1;

	rbd_assert(length <= U64_MAX - offset);
	if (offset + length > segment_size)
		length = segment_size - offset;

	return length;
}

/*
 * returns the size of an object in the image
 */
static u64 rbd_obj_bytes(struct rbd_image_header *header)
{
	return 1 << header->obj_order;
}

/*
 * bio helpers
 */

static void bio_chain_put(struct bio *chain)
{
	struct bio *tmp;

	while (chain) {
		tmp = chain;
		chain = chain->bi_next;
		bio_put(tmp);
	}
}

/*
 * zeros a bio chain, starting at specific offset
 */
static void zero_bio_chain(struct bio *chain, int start_ofs)
{
	struct bio_vec *bv;
	unsigned long flags;
	void *buf;
	int i;
	int pos = 0;

	while (chain) {
		bio_for_each_segment(bv, chain, i) {
			if (pos + bv->bv_len > start_ofs) {
				int remainder = max(start_ofs - pos, 0);
				buf = bvec_kmap_irq(bv, &flags);
				memset(buf + remainder, 0,
				       bv->bv_len - remainder);
				flush_dcache_page(bv->bv_page);
				bvec_kunmap_irq(buf, &flags);
			}
			pos += bv->bv_len;
		}

		chain = chain->bi_next;
	}
}

/*
 * similar to zero_bio_chain(), zeros data defined by a page array,
 * starting at the given byte offset from the start of the array and
 * continuing up to the given end offset.  The pages array is
 * assumed to be big enough to hold all bytes up to the end.
 */
static void zero_pages(struct page **pages, u64 offset, u64 end)
{
	struct page **page = &pages[offset >> PAGE_SHIFT];

	rbd_assert(end > offset);
	rbd_assert(end - offset <= (u64)SIZE_MAX);
	while (offset < end) {
		size_t page_offset;
		size_t length;
		unsigned long flags;
		void *kaddr;

		page_offset = offset & ~PAGE_MASK;
		length = min_t(size_t, PAGE_SIZE - page_offset, end - offset);
		local_irq_save(flags);
		kaddr = kmap_atomic(*page);
		memset(kaddr + page_offset, 0, length);
		flush_dcache_page(*page);
		kunmap_atomic(kaddr);
		local_irq_restore(flags);

		offset += length;
		page++;
	}
}

/*
 * Clone a portion of a bio, starting at the given byte offset
 * and continuing for the number of bytes indicated.
 */
static struct bio *bio_clone_range(struct bio *bio_src,
					unsigned int offset,
					unsigned int len,
					gfp_t gfpmask)
{
	struct bio_vec *bv;
	unsigned int resid;
	unsigned short idx;
	unsigned int voff;
	unsigned short end_idx;
	unsigned short vcnt;
	struct bio *bio;

	/* Handle the easy case for the caller */

	if (!offset && len == bio_src->bi_size)
		return bio_clone(bio_src, gfpmask);

	if (WARN_ON_ONCE(!len))
		return NULL;
	if (WARN_ON_ONCE(len > bio_src->bi_size))
		return NULL;
	if (WARN_ON_ONCE(offset > bio_src->bi_size - len))
		return NULL;

	/* Find first affected segment... */

	resid = offset;
	bio_for_each_segment(bv, bio_src, idx) {
		if (resid < bv->bv_len)
			break;
		resid -= bv->bv_len;
	}
	voff = resid;

	/* ...and the last affected segment */

	resid += len;
	__bio_for_each_segment(bv, bio_src, end_idx, idx) {
		if (resid <= bv->bv_len)
			break;
		resid -= bv->bv_len;
	}
	vcnt = end_idx - idx + 1;

	/* Build the clone */

	bio = bio_alloc(gfpmask, (unsigned int) vcnt);
	if (!bio)
		return NULL;	/* ENOMEM */

	bio->bi_bdev = bio_src->bi_bdev;
	bio->bi_sector = bio_src->bi_sector + (offset >> SECTOR_SHIFT);
	bio->bi_rw = bio_src->bi_rw;
	bio->bi_flags |= 1 << BIO_CLONED;

	/*
	 * Copy over our part of the bio_vec, then update the first
	 * and last (or only) entries.
	 */
	memcpy(&bio->bi_io_vec[0], &bio_src->bi_io_vec[idx],
			vcnt * sizeof (struct bio_vec));
	bio->bi_io_vec[0].bv_offset += voff;
	if (vcnt > 1) {
		bio->bi_io_vec[0].bv_len -= voff;
		bio->bi_io_vec[vcnt - 1].bv_len = resid;
	} else {
		bio->bi_io_vec[0].bv_len = len;
	}

	bio->bi_vcnt = vcnt;
	bio->bi_size = len;
	bio->bi_idx = 0;

	return bio;
}

/*
 * Clone a portion of a bio chain, starting at the given byte offset
 * into the first bio in the source chain and continuing for the
 * number of bytes indicated.  The result is another bio chain of
 * exactly the given length, or a null pointer on error.
 *
 * The bio_src and offset parameters are both in-out.  On entry they
 * refer to the first source bio and the offset into that bio where
 * the start of data to be cloned is located.
 *
 * On return, bio_src is updated to refer to the bio in the source
 * chain that contains first un-cloned byte, and *offset will
 * contain the offset of that byte within that bio.
 */
static struct bio *bio_chain_clone_range(struct bio **bio_src,
					unsigned int *offset,
					unsigned int len,
					gfp_t gfpmask)
{
	struct bio *bi = *bio_src;
	unsigned int off = *offset;
	struct bio *chain = NULL;
	struct bio **end;

	/* Build up a chain of clone bios up to the limit */

	if (!bi || off >= bi->bi_size || !len)
		return NULL;		/* Nothing to clone */

	end = &chain;
	while (len) {
		unsigned int bi_size;
		struct bio *bio;

		if (!bi) {
			rbd_warn(NULL, "bio_chain exhausted with %u left", len);
			goto out_err;	/* EINVAL; ran out of bio's */
		}
		bi_size = min_t(unsigned int, bi->bi_size - off, len);
		bio = bio_clone_range(bi, off, bi_size, gfpmask);
		if (!bio)
			goto out_err;	/* ENOMEM */

		*end = bio;
		end = &bio->bi_next;

		off += bi_size;
		if (off == bi->bi_size) {
			bi = bi->bi_next;
			off = 0;
		}
		len -= bi_size;
	}
	*bio_src = bi;
	*offset = off;

	return chain;
out_err:
	bio_chain_put(chain);

	return NULL;
}

/*
 * The default/initial value for all object request flags is 0.  For
 * each flag, once its value is set to 1 it is never reset to 0
 * again.
 */
static void obj_request_img_data_set(struct rbd_obj_request *obj_request)
{
	if (test_and_set_bit(OBJ_REQ_IMG_DATA, &obj_request->flags)) {
		struct rbd_device *rbd_dev;

		rbd_dev = obj_request->img_request->rbd_dev;
		rbd_warn(rbd_dev, "obj_request %p already marked img_data\n",
			obj_request);
	}
}

static bool obj_request_img_data_test(struct rbd_obj_request *obj_request)
{
	smp_mb();
	return test_bit(OBJ_REQ_IMG_DATA, &obj_request->flags) != 0;
}

static void obj_request_done_set(struct rbd_obj_request *obj_request)
{
	if (test_and_set_bit(OBJ_REQ_DONE, &obj_request->flags)) {
		struct rbd_device *rbd_dev = NULL;

		if (obj_request_img_data_test(obj_request))
			rbd_dev = obj_request->img_request->rbd_dev;
		rbd_warn(rbd_dev, "obj_request %p already marked done\n",
			obj_request);
	}
}

static bool obj_request_done_test(struct rbd_obj_request *obj_request)
{
	smp_mb();
	return test_bit(OBJ_REQ_DONE, &obj_request->flags) != 0;
}

/*
 * This sets the KNOWN flag after (possibly) setting the EXISTS
 * flag.  The latter is set based on the "exists" value provided.
 *
 * Note that for our purposes once an object exists it never goes
 * away again.  It's possible that the response from two existence
 * checks are separated by the creation of the target object, and
 * the first ("doesn't exist") response arrives *after* the second
 * ("does exist").  In that case we ignore the second one.
 */
static void obj_request_existence_set(struct rbd_obj_request *obj_request,
				bool exists)
{
	if (exists)
		set_bit(OBJ_REQ_EXISTS, &obj_request->flags);
	set_bit(OBJ_REQ_KNOWN, &obj_request->flags);
	smp_mb();
}

static bool obj_request_known_test(struct rbd_obj_request *obj_request)
{
	smp_mb();
	return test_bit(OBJ_REQ_KNOWN, &obj_request->flags) != 0;
}

static bool obj_request_exists_test(struct rbd_obj_request *obj_request)
{
	smp_mb();
	return test_bit(OBJ_REQ_EXISTS, &obj_request->flags) != 0;
}

static bool obj_request_overlaps_parent(struct rbd_obj_request *obj_request)
{
	struct rbd_device *rbd_dev = obj_request->img_request->rbd_dev;

	return obj_request->img_offset <
	    round_up(rbd_dev->parent_overlap, rbd_obj_bytes(&rbd_dev->header));
}

static void rbd_obj_request_get(struct rbd_obj_request *obj_request)
{
	dout("%s: obj %p (was %d)\n", __func__, obj_request,
		atomic_read(&obj_request->kref.refcount));
	kref_get(&obj_request->kref);
}

static void rbd_obj_request_destroy(struct kref *kref);
static void rbd_obj_request_put(struct rbd_obj_request *obj_request)
{
	rbd_assert(obj_request != NULL);
	dout("%s: obj %p (was %d)\n", __func__, obj_request,
		atomic_read(&obj_request->kref.refcount));
	kref_put(&obj_request->kref, rbd_obj_request_destroy);
}

static void rbd_img_request_get(struct rbd_img_request *img_request)
{
	dout("%s: img %p (was %d)\n", __func__, img_request,
	     atomic_read(&img_request->kref.refcount));
	kref_get(&img_request->kref);
}

static bool img_request_child_test(struct rbd_img_request *img_request);
static void rbd_parent_request_destroy(struct kref *kref);
static void rbd_img_request_destroy(struct kref *kref);
static void rbd_img_request_put(struct rbd_img_request *img_request)
{
	rbd_assert(img_request != NULL);
	dout("%s: img %p (was %d)\n", __func__, img_request,
		atomic_read(&img_request->kref.refcount));
	if (img_request_child_test(img_request))
		kref_put(&img_request->kref, rbd_parent_request_destroy);
	else
		kref_put(&img_request->kref, rbd_img_request_destroy);
}

static inline void rbd_img_obj_request_add(struct rbd_img_request *img_request,
					struct rbd_obj_request *obj_request)
{
	rbd_assert(obj_request->img_request == NULL);

	/* Image request now owns object's original reference */
	obj_request->img_request = img_request;
	obj_request->which = img_request->obj_request_count;
	rbd_assert(!obj_request_img_data_test(obj_request));
	obj_request_img_data_set(obj_request);
	rbd_assert(obj_request->which != BAD_WHICH);
	img_request->obj_request_count++;
	list_add_tail(&obj_request->links, &img_request->obj_requests);
	dout("%s: img %p obj %p w=%u\n", __func__, img_request, obj_request,
		obj_request->which);
}

static inline void rbd_img_obj_request_del(struct rbd_img_request *img_request,
					struct rbd_obj_request *obj_request)
{
	rbd_assert(obj_request->which != BAD_WHICH);

	dout("%s: img %p obj %p w=%u\n", __func__, img_request, obj_request,
		obj_request->which);
	list_del(&obj_request->links);
	rbd_assert(img_request->obj_request_count > 0);
	img_request->obj_request_count--;
	rbd_assert(obj_request->which == img_request->obj_request_count);
	obj_request->which = BAD_WHICH;
	rbd_assert(obj_request_img_data_test(obj_request));
	rbd_assert(obj_request->img_request == img_request);
	obj_request->img_request = NULL;
	obj_request->callback = NULL;
	rbd_obj_request_put(obj_request);
}

static bool obj_request_type_valid(enum obj_request_type type)
{
	switch (type) {
	case OBJ_REQUEST_NODATA:
	case OBJ_REQUEST_BIO:
	case OBJ_REQUEST_PAGES:
		return true;
	default:
		return false;
	}
}

static int rbd_obj_request_submit(struct ceph_osd_client *osdc,
				struct rbd_obj_request *obj_request)
{
	dout("%s: osdc %p obj %p\n", __func__, osdc, obj_request);

	return ceph_osdc_start_request(osdc, obj_request->osd_req, false);
}

static void rbd_img_request_complete(struct rbd_img_request *img_request)
{

	dout("%s: img %p\n", __func__, img_request);

	/*
	 * If no error occurred, compute the aggregate transfer
	 * count for the image request.  We could instead use
	 * atomic64_cmpxchg() to update it as each object request
	 * completes; not clear which way is better off hand.
	 */
	if (!img_request->result) {
		struct rbd_obj_request *obj_request;
		u64 xferred = 0;

		for_each_obj_request(img_request, obj_request)
			xferred += obj_request->xferred;
		img_request->xferred = xferred;
	}

	if (img_request->callback)
		img_request->callback(img_request);
	else
		rbd_img_request_put(img_request);
}

/* Caller is responsible for rbd_obj_request_destroy(obj_request) */

static int rbd_obj_request_wait(struct rbd_obj_request *obj_request)
{
	dout("%s: obj %p\n", __func__, obj_request);

	return wait_for_completion_interruptible(&obj_request->completion);
}

/*
 * The default/initial value for all image request flags is 0.  Each
 * is conditionally set to 1 at image request initialization time
 * and currently never change thereafter.
 */
static void img_request_write_set(struct rbd_img_request *img_request)
{
	set_bit(IMG_REQ_WRITE, &img_request->flags);
	smp_mb();
}

static bool img_request_write_test(struct rbd_img_request *img_request)
{
	smp_mb();
	return test_bit(IMG_REQ_WRITE, &img_request->flags) != 0;
}

static void img_request_child_set(struct rbd_img_request *img_request)
{
	set_bit(IMG_REQ_CHILD, &img_request->flags);
	smp_mb();
}

static void img_request_child_clear(struct rbd_img_request *img_request)
{
	clear_bit(IMG_REQ_CHILD, &img_request->flags);
	smp_mb();
}

static bool img_request_child_test(struct rbd_img_request *img_request)
{
	smp_mb();
	return test_bit(IMG_REQ_CHILD, &img_request->flags) != 0;
}

static void img_request_layered_set(struct rbd_img_request *img_request)
{
	set_bit(IMG_REQ_LAYERED, &img_request->flags);
	smp_mb();
}

static void img_request_layered_clear(struct rbd_img_request *img_request)
{
	clear_bit(IMG_REQ_LAYERED, &img_request->flags);
	smp_mb();
}

static bool img_request_layered_test(struct rbd_img_request *img_request)
{
	smp_mb();
	return test_bit(IMG_REQ_LAYERED, &img_request->flags) != 0;
}

static void
rbd_img_obj_request_read_callback(struct rbd_obj_request *obj_request)
{
	u64 xferred = obj_request->xferred;
	u64 length = obj_request->length;

	dout("%s: obj %p img %p result %d %llu/%llu\n", __func__,
		obj_request, obj_request->img_request, obj_request->result,
		xferred, length);
	/*
	 * ENOENT means a hole in the image.  We zero-fill the entire
	 * length of the request.  A short read also implies zero-fill
	 * to the end of the request.  An error requires the whole
	 * length of the request to be reported finished with an error
	 * to the block layer.  In each case we update the xferred
	 * count to indicate the whole request was satisfied.
	 */
	rbd_assert(obj_request->type != OBJ_REQUEST_NODATA);
	if (obj_request->result == -ENOENT) {
		if (obj_request->type == OBJ_REQUEST_BIO)
			zero_bio_chain(obj_request->bio_list, 0);
		else
			zero_pages(obj_request->pages, 0, length);
		obj_request->result = 0;
	} else if (xferred < length && !obj_request->result) {
		if (obj_request->type == OBJ_REQUEST_BIO)
			zero_bio_chain(obj_request->bio_list, xferred);
		else
			zero_pages(obj_request->pages, xferred, length);
	}
	obj_request->xferred = length;
	obj_request_done_set(obj_request);
}

static void rbd_obj_request_complete(struct rbd_obj_request *obj_request)
{
	dout("%s: obj %p cb %p\n", __func__, obj_request,
		obj_request->callback);
	if (obj_request->callback)
		obj_request->callback(obj_request);
	else
		complete_all(&obj_request->completion);
}

static void rbd_osd_trivial_callback(struct rbd_obj_request *obj_request)
{
	dout("%s: obj %p\n", __func__, obj_request);
	obj_request_done_set(obj_request);
}

static void rbd_osd_read_callback(struct rbd_obj_request *obj_request)
{
	struct rbd_img_request *img_request = NULL;
	struct rbd_device *rbd_dev = NULL;
	bool layered = false;

	if (obj_request_img_data_test(obj_request)) {
		img_request = obj_request->img_request;
		layered = img_request && img_request_layered_test(img_request);
		rbd_dev = img_request->rbd_dev;
	}

	dout("%s: obj %p img %p result %d %llu/%llu\n", __func__,
		obj_request, img_request, obj_request->result,
		obj_request->xferred, obj_request->length);
	if (layered && obj_request->result == -ENOENT &&
			obj_request->img_offset < rbd_dev->parent_overlap)
		rbd_img_parent_read(obj_request);
	else if (img_request)
		rbd_img_obj_request_read_callback(obj_request);
	else
		obj_request_done_set(obj_request);
}

static void rbd_osd_write_callback(struct rbd_obj_request *obj_request)
{
	dout("%s: obj %p result %d %llu\n", __func__, obj_request,
		obj_request->result, obj_request->length);
	/*
	 * There is no such thing as a successful short write.  Set
	 * it to our originally-requested length.
	 */
	obj_request->xferred = obj_request->length;
	obj_request_done_set(obj_request);
}

/*
 * For a simple stat call there's nothing to do.  We'll do more if
 * this is part of a write sequence for a layered image.
 */
static void rbd_osd_stat_callback(struct rbd_obj_request *obj_request)
{
	dout("%s: obj %p\n", __func__, obj_request);
	obj_request_done_set(obj_request);
}

static void rbd_osd_req_callback(struct ceph_osd_request *osd_req,
				struct ceph_msg *msg)
{
	struct rbd_obj_request *obj_request = osd_req->r_priv;
	u16 opcode;

	dout("%s: osd_req %p msg %p\n", __func__, osd_req, msg);
	rbd_assert(osd_req == obj_request->osd_req);
	if (obj_request_img_data_test(obj_request)) {
		rbd_assert(obj_request->img_request);
		rbd_assert(obj_request->which != BAD_WHICH);
	} else {
		rbd_assert(obj_request->which == BAD_WHICH);
	}

	if (osd_req->r_result < 0)
		obj_request->result = osd_req->r_result;

	BUG_ON(osd_req->r_num_ops > 2);

	/*
	 * We support a 64-bit length, but ultimately it has to be
	 * passed to blk_end_request(), which takes an unsigned int.
	 */
	obj_request->xferred = osd_req->r_reply_op_len[0];
	rbd_assert(obj_request->xferred < (u64)UINT_MAX);
	opcode = osd_req->r_ops[0].op;
	switch (opcode) {
	case CEPH_OSD_OP_READ:
		rbd_osd_read_callback(obj_request);
		break;
	case CEPH_OSD_OP_WRITE:
		rbd_osd_write_callback(obj_request);
		break;
	case CEPH_OSD_OP_STAT:
		rbd_osd_stat_callback(obj_request);
		break;
	case CEPH_OSD_OP_CALL:
	case CEPH_OSD_OP_NOTIFY_ACK:
	case CEPH_OSD_OP_WATCH:
		rbd_osd_trivial_callback(obj_request);
		break;
	default:
		rbd_warn(NULL, "%s: unsupported op %hu\n",
			obj_request->object_name, (unsigned short) opcode);
		break;
	}

	if (obj_request_done_test(obj_request))
		rbd_obj_request_complete(obj_request);
}

static void rbd_osd_req_format_read(struct rbd_obj_request *obj_request)
{
	struct rbd_img_request *img_request = obj_request->img_request;
	struct ceph_osd_request *osd_req = obj_request->osd_req;
	u64 snap_id;

	rbd_assert(osd_req != NULL);

	snap_id = img_request ? img_request->snap_id : CEPH_NOSNAP;
	ceph_osdc_build_request(osd_req, obj_request->offset,
			NULL, snap_id, NULL);
}

static void rbd_osd_req_format_write(struct rbd_obj_request *obj_request)
{
	struct rbd_img_request *img_request = obj_request->img_request;
	struct ceph_osd_request *osd_req = obj_request->osd_req;
	struct ceph_snap_context *snapc;
	struct timespec mtime = CURRENT_TIME;

	rbd_assert(osd_req != NULL);

	snapc = img_request ? img_request->snapc : NULL;
	ceph_osdc_build_request(osd_req, obj_request->offset,
			snapc, CEPH_NOSNAP, &mtime);
}

static struct ceph_osd_request *rbd_osd_req_create(
					struct rbd_device *rbd_dev,
					bool write_request,
					struct rbd_obj_request *obj_request)
{
	struct ceph_snap_context *snapc = NULL;
	struct ceph_osd_client *osdc;
	struct ceph_osd_request *osd_req;

	if (obj_request_img_data_test(obj_request)) {
		struct rbd_img_request *img_request = obj_request->img_request;

		rbd_assert(write_request ==
				img_request_write_test(img_request));
		if (write_request)
			snapc = img_request->snapc;
	}

	/* Allocate and initialize the request, for the single op */

	osdc = &rbd_dev->rbd_client->client->osdc;
	osd_req = ceph_osdc_alloc_request(osdc, snapc, 1, false, GFP_ATOMIC);
	if (!osd_req)
		return NULL;	/* ENOMEM */

	if (write_request)
		osd_req->r_flags = CEPH_OSD_FLAG_WRITE | CEPH_OSD_FLAG_ONDISK;
	else
		osd_req->r_flags = CEPH_OSD_FLAG_READ;

	osd_req->r_callback = rbd_osd_req_callback;
	osd_req->r_priv = obj_request;

	osd_req->r_oid_len = strlen(obj_request->object_name);
	rbd_assert(osd_req->r_oid_len < sizeof (osd_req->r_oid));
	memcpy(osd_req->r_oid, obj_request->object_name, osd_req->r_oid_len);

	osd_req->r_file_layout = rbd_dev->layout;	/* struct */

	return osd_req;
}

/*
 * Create a copyup osd request based on the information in the
 * object request supplied.  A copyup request has two osd ops,
 * a copyup method call, and a "normal" write request.
 */
static struct ceph_osd_request *
rbd_osd_req_create_copyup(struct rbd_obj_request *obj_request)
{
	struct rbd_img_request *img_request;
	struct ceph_snap_context *snapc;
	struct rbd_device *rbd_dev;
	struct ceph_osd_client *osdc;
	struct ceph_osd_request *osd_req;

	rbd_assert(obj_request_img_data_test(obj_request));
	img_request = obj_request->img_request;
	rbd_assert(img_request);
	rbd_assert(img_request_write_test(img_request));

	/* Allocate and initialize the request, for the two ops */

	snapc = img_request->snapc;
	rbd_dev = img_request->rbd_dev;
	osdc = &rbd_dev->rbd_client->client->osdc;
	osd_req = ceph_osdc_alloc_request(osdc, snapc, 2, false, GFP_ATOMIC);
	if (!osd_req)
		return NULL;	/* ENOMEM */

	osd_req->r_flags = CEPH_OSD_FLAG_WRITE | CEPH_OSD_FLAG_ONDISK;
	osd_req->r_callback = rbd_osd_req_callback;
	osd_req->r_priv = obj_request;

	osd_req->r_oid_len = strlen(obj_request->object_name);
	rbd_assert(osd_req->r_oid_len < sizeof (osd_req->r_oid));
	memcpy(osd_req->r_oid, obj_request->object_name, osd_req->r_oid_len);

	osd_req->r_file_layout = rbd_dev->layout;	/* struct */

	return osd_req;
}


static void rbd_osd_req_destroy(struct ceph_osd_request *osd_req)
{
	ceph_osdc_put_request(osd_req);
}

/* object_name is assumed to be a non-null pointer and NUL-terminated */

static struct rbd_obj_request *rbd_obj_request_create(const char *object_name,
						u64 offset, u64 length,
						enum obj_request_type type)
{
	struct rbd_obj_request *obj_request;
	size_t size;
	char *name;

	rbd_assert(obj_request_type_valid(type));

	size = strlen(object_name) + 1;
	name = kmalloc(size, GFP_KERNEL);
	if (!name)
		return NULL;

	obj_request = kmem_cache_zalloc(rbd_obj_request_cache, GFP_KERNEL);
	if (!obj_request) {
		kfree(name);
		return NULL;
	}

	obj_request->object_name = memcpy(name, object_name, size);
	obj_request->offset = offset;
	obj_request->length = length;
	obj_request->flags = 0;
	obj_request->which = BAD_WHICH;
	obj_request->type = type;
	INIT_LIST_HEAD(&obj_request->links);
	init_completion(&obj_request->completion);
	kref_init(&obj_request->kref);

	dout("%s: \"%s\" %llu/%llu %d -> obj %p\n", __func__, object_name,
		offset, length, (int)type, obj_request);

	return obj_request;
}

static void rbd_obj_request_destroy(struct kref *kref)
{
	struct rbd_obj_request *obj_request;

	obj_request = container_of(kref, struct rbd_obj_request, kref);

	dout("%s: obj %p\n", __func__, obj_request);

	rbd_assert(obj_request->img_request == NULL);
	rbd_assert(obj_request->which == BAD_WHICH);

	if (obj_request->osd_req)
		rbd_osd_req_destroy(obj_request->osd_req);

	rbd_assert(obj_request_type_valid(obj_request->type));
	switch (obj_request->type) {
	case OBJ_REQUEST_NODATA:
		break;		/* Nothing to do */
	case OBJ_REQUEST_BIO:
		if (obj_request->bio_list)
			bio_chain_put(obj_request->bio_list);
		break;
	case OBJ_REQUEST_PAGES:
		if (obj_request->pages)
			ceph_release_page_vector(obj_request->pages,
						obj_request->page_count);
		break;
	}

	kfree(obj_request->object_name);
	obj_request->object_name = NULL;
	kmem_cache_free(rbd_obj_request_cache, obj_request);
}

/* It's OK to call this for a device with no parent */

static void rbd_spec_put(struct rbd_spec *spec);
static void rbd_dev_unparent(struct rbd_device *rbd_dev)
{
	rbd_dev_remove_parent(rbd_dev);
	rbd_spec_put(rbd_dev->parent_spec);
	rbd_dev->parent_spec = NULL;
	rbd_dev->parent_overlap = 0;
}

/*
 * Parent image reference counting is used to determine when an
 * image's parent fields can be safely torn down--after there are no
 * more in-flight requests to the parent image.  When the last
 * reference is dropped, cleaning them up is safe.
 */
static void rbd_dev_parent_put(struct rbd_device *rbd_dev)
{
	int counter;

	if (!rbd_dev->parent_spec)
		return;

	counter = atomic_dec_return_safe(&rbd_dev->parent_ref);
	if (counter > 0)
		return;

	/* Last reference; clean up parent data structures */

	if (!counter)
		rbd_dev_unparent(rbd_dev);
	else
		rbd_warn(rbd_dev, "parent reference underflow\n");
}

/*
 * If an image has a non-zero parent overlap, get a reference to its
 * parent.
 *
 * We must get the reference before checking for the overlap to
 * coordinate properly with zeroing the parent overlap in
 * rbd_dev_v2_parent_info() when an image gets flattened.  We
 * drop it again if there is no overlap.
 *
 * Returns true if the rbd device has a parent with a non-zero
 * overlap and a reference for it was successfully taken, or
 * false otherwise.
 */
static bool rbd_dev_parent_get(struct rbd_device *rbd_dev)
{
	int counter;

	if (!rbd_dev->parent_spec)
		return false;

	counter = atomic_inc_return_safe(&rbd_dev->parent_ref);
	if (counter > 0 && rbd_dev->parent_overlap)
		return true;

	/* Image was flattened, but parent is not yet torn down */

	if (counter < 0)
		rbd_warn(rbd_dev, "parent reference overflow\n");

	return false;
}

/*
 * Caller is responsible for filling in the list of object requests
 * that comprises the image request, and the Linux request pointer
 * (if there is one).
 */
static struct rbd_img_request *rbd_img_request_create(
					struct rbd_device *rbd_dev,
					u64 offset, u64 length,
					bool write_request)
{
	struct rbd_img_request *img_request;

	img_request = kmem_cache_alloc(rbd_img_request_cache, GFP_ATOMIC);
	if (!img_request)
		return NULL;

	if (write_request) {
		down_read(&rbd_dev->header_rwsem);
		ceph_get_snap_context(rbd_dev->header.snapc);
		up_read(&rbd_dev->header_rwsem);
	}

	img_request->rq = NULL;
	img_request->rbd_dev = rbd_dev;
	img_request->offset = offset;
	img_request->length = length;
	img_request->flags = 0;
	if (write_request) {
		img_request_write_set(img_request);
		img_request->snapc = rbd_dev->header.snapc;
	} else {
		img_request->snap_id = rbd_dev->spec->snap_id;
	}
	if (rbd_dev_parent_get(rbd_dev))
		img_request_layered_set(img_request);
	spin_lock_init(&img_request->completion_lock);
	img_request->next_completion = 0;
	img_request->callback = NULL;
	img_request->result = 0;
	img_request->obj_request_count = 0;
	INIT_LIST_HEAD(&img_request->obj_requests);
	kref_init(&img_request->kref);

	dout("%s: rbd_dev %p %s %llu/%llu -> img %p\n", __func__, rbd_dev,
		write_request ? "write" : "read", offset, length,
		img_request);

	return img_request;
}

static void rbd_img_request_destroy(struct kref *kref)
{
	struct rbd_img_request *img_request;
	struct rbd_obj_request *obj_request;
	struct rbd_obj_request *next_obj_request;

	img_request = container_of(kref, struct rbd_img_request, kref);

	dout("%s: img %p\n", __func__, img_request);

	for_each_obj_request_safe(img_request, obj_request, next_obj_request)
		rbd_img_obj_request_del(img_request, obj_request);
	rbd_assert(img_request->obj_request_count == 0);

	if (img_request_layered_test(img_request)) {
		img_request_layered_clear(img_request);
		rbd_dev_parent_put(img_request->rbd_dev);
	}

	if (img_request_write_test(img_request))
		ceph_put_snap_context(img_request->snapc);

	kmem_cache_free(rbd_img_request_cache, img_request);
}

static struct rbd_img_request *rbd_parent_request_create(
					struct rbd_obj_request *obj_request,
					u64 img_offset, u64 length)
{
	struct rbd_img_request *parent_request;
	struct rbd_device *rbd_dev;

	rbd_assert(obj_request->img_request);
	rbd_dev = obj_request->img_request->rbd_dev;

	parent_request = rbd_img_request_create(rbd_dev->parent,
						img_offset, length, false);
	if (!parent_request)
		return NULL;

	img_request_child_set(parent_request);
	rbd_obj_request_get(obj_request);
	parent_request->obj_request = obj_request;

	return parent_request;
}

static void rbd_parent_request_destroy(struct kref *kref)
{
	struct rbd_img_request *parent_request;
	struct rbd_obj_request *orig_request;

	parent_request = container_of(kref, struct rbd_img_request, kref);
	orig_request = parent_request->obj_request;

	parent_request->obj_request = NULL;
	rbd_obj_request_put(orig_request);
	img_request_child_clear(parent_request);

	rbd_img_request_destroy(kref);
}

static bool rbd_img_obj_end_request(struct rbd_obj_request *obj_request)
{
	struct rbd_img_request *img_request;
	unsigned int xferred;
	int result;
	bool more;

	rbd_assert(obj_request_img_data_test(obj_request));
	img_request = obj_request->img_request;

	rbd_assert(obj_request->xferred <= (u64)UINT_MAX);
	xferred = (unsigned int)obj_request->xferred;
	result = obj_request->result;
	if (result) {
		struct rbd_device *rbd_dev = img_request->rbd_dev;

		rbd_warn(rbd_dev, "%s %llx at %llx (%llx)\n",
			img_request_write_test(img_request) ? "write" : "read",
			obj_request->length, obj_request->img_offset,
			obj_request->offset);
		rbd_warn(rbd_dev, "  result %d xferred %x\n",
			result, xferred);
		if (!img_request->result)
			img_request->result = result;
	}

	/* Image object requests don't own their page array */

	if (obj_request->type == OBJ_REQUEST_PAGES) {
		obj_request->pages = NULL;
		obj_request->page_count = 0;
	}

	if (img_request_child_test(img_request)) {
		rbd_assert(img_request->obj_request != NULL);
		more = obj_request->which < img_request->obj_request_count - 1;
	} else {
		rbd_assert(img_request->rq != NULL);
		more = blk_end_request(img_request->rq, result, xferred);
	}

	return more;
}

static void rbd_img_obj_callback(struct rbd_obj_request *obj_request)
{
	struct rbd_img_request *img_request;
	u32 which = obj_request->which;
	bool more = true;

	rbd_assert(obj_request_img_data_test(obj_request));
	img_request = obj_request->img_request;

	dout("%s: img %p obj %p\n", __func__, img_request, obj_request);
	rbd_assert(img_request != NULL);
	rbd_assert(img_request->obj_request_count > 0);
	rbd_assert(which != BAD_WHICH);
	rbd_assert(which < img_request->obj_request_count);
	rbd_assert(which >= img_request->next_completion);

	spin_lock_irq(&img_request->completion_lock);
	if (which != img_request->next_completion)
		goto out;

	for_each_obj_request_from(img_request, obj_request) {
		rbd_assert(more);
		rbd_assert(which < img_request->obj_request_count);

		if (!obj_request_done_test(obj_request))
			break;
		more = rbd_img_obj_end_request(obj_request);
		which++;
	}

	rbd_assert(more ^ (which == img_request->obj_request_count));
	img_request->next_completion = which;
out:
	spin_unlock_irq(&img_request->completion_lock);
	rbd_img_request_put(img_request);

	if (!more)
		rbd_img_request_complete(img_request);
}

/*
 * Split up an image request into one or more object requests, each
 * to a different object.  The "type" parameter indicates whether
 * "data_desc" is the pointer to the head of a list of bio
 * structures, or the base of a page array.  In either case this
 * function assumes data_desc describes memory sufficient to hold
 * all data described by the image request.
 */
static int rbd_img_request_fill(struct rbd_img_request *img_request,
					enum obj_request_type type,
					void *data_desc)
{
	struct rbd_device *rbd_dev = img_request->rbd_dev;
	struct rbd_obj_request *obj_request = NULL;
	struct rbd_obj_request *next_obj_request;
	bool write_request = img_request_write_test(img_request);
	struct bio *bio_list = NULL;
	unsigned int bio_offset = 0;
	struct page **pages = NULL;
	u64 img_offset;
	u64 resid;
	u16 opcode;

	dout("%s: img %p type %d data_desc %p\n", __func__, img_request,
		(int)type, data_desc);

	opcode = write_request ? CEPH_OSD_OP_WRITE : CEPH_OSD_OP_READ;
	img_offset = img_request->offset;
	resid = img_request->length;
	rbd_assert(resid > 0);

	if (type == OBJ_REQUEST_BIO) {
		bio_list = data_desc;
		rbd_assert(img_offset == bio_list->bi_sector << SECTOR_SHIFT);
	} else {
		rbd_assert(type == OBJ_REQUEST_PAGES);
		pages = data_desc;
	}

	while (resid) {
		struct ceph_osd_request *osd_req;
		const char *object_name;
		u64 offset;
		u64 length;

		object_name = rbd_segment_name(rbd_dev, img_offset);
		if (!object_name)
			goto out_unwind;
		offset = rbd_segment_offset(rbd_dev, img_offset);
		length = rbd_segment_length(rbd_dev, img_offset, resid);
		obj_request = rbd_obj_request_create(object_name,
						offset, length, type);
		/* object request has its own copy of the object name */
		rbd_segment_name_free(object_name);
		if (!obj_request)
			goto out_unwind;
		/*
		 * set obj_request->img_request before creating the
		 * osd_request so that it gets the right snapc
		 */
		rbd_img_obj_request_add(img_request, obj_request);

		if (type == OBJ_REQUEST_BIO) {
			unsigned int clone_size;

			rbd_assert(length <= (u64)UINT_MAX);
			clone_size = (unsigned int)length;
			obj_request->bio_list =
					bio_chain_clone_range(&bio_list,
								&bio_offset,
								clone_size,
								GFP_ATOMIC);
			if (!obj_request->bio_list)
				goto out_partial;
		} else {
			unsigned int page_count;

			obj_request->pages = pages;
			page_count = (u32)calc_pages_for(offset, length);
			obj_request->page_count = page_count;
			if ((offset + length) & ~PAGE_MASK)
				page_count--;	/* more on last page */
			pages += page_count;
		}

		osd_req = rbd_osd_req_create(rbd_dev, write_request,
						obj_request);
		if (!osd_req)
			goto out_partial;
		obj_request->osd_req = osd_req;
		obj_request->callback = rbd_img_obj_callback;
		rbd_img_request_get(img_request);

		osd_req_op_extent_init(osd_req, 0, opcode, offset, length,
						0, 0);
		if (type == OBJ_REQUEST_BIO)
			osd_req_op_extent_osd_data_bio(osd_req, 0,
					obj_request->bio_list, length);
		else
			osd_req_op_extent_osd_data_pages(osd_req, 0,
					obj_request->pages, length,
					offset & ~PAGE_MASK, false, false);

		if (write_request)
			rbd_osd_req_format_write(obj_request);
		else
			rbd_osd_req_format_read(obj_request);

		obj_request->img_offset = img_offset;

		img_offset += length;
		resid -= length;
	}

	return 0;

out_partial:
	rbd_obj_request_put(obj_request);
out_unwind:
	for_each_obj_request_safe(img_request, obj_request, next_obj_request)
		rbd_img_obj_request_del(img_request, obj_request);

	return -ENOMEM;
}

static void
rbd_img_obj_copyup_callback(struct rbd_obj_request *obj_request)
{
	struct rbd_img_request *img_request;
	struct rbd_device *rbd_dev;
	struct page **pages;
	u32 page_count;

	rbd_assert(obj_request->type == OBJ_REQUEST_BIO);
	rbd_assert(obj_request_img_data_test(obj_request));
	img_request = obj_request->img_request;
	rbd_assert(img_request);

	rbd_dev = img_request->rbd_dev;
	rbd_assert(rbd_dev);

	pages = obj_request->copyup_pages;
	rbd_assert(pages != NULL);
	obj_request->copyup_pages = NULL;
	page_count = obj_request->copyup_page_count;
	rbd_assert(page_count);
	obj_request->copyup_page_count = 0;
	ceph_release_page_vector(pages, page_count);

	/*
	 * We want the transfer count to reflect the size of the
	 * original write request.  There is no such thing as a
	 * successful short write, so if the request was successful
	 * we can just set it to the originally-requested length.
	 */
	if (!obj_request->result)
		obj_request->xferred = obj_request->length;

	/* Finish up with the normal image object callback */

	rbd_img_obj_callback(obj_request);
}

static void
rbd_img_obj_parent_read_full_callback(struct rbd_img_request *img_request)
{
	struct rbd_obj_request *orig_request;
	struct ceph_osd_request *osd_req;
	struct ceph_osd_client *osdc;
	struct rbd_device *rbd_dev;
	struct page **pages;
	u32 page_count;
	int img_result;
	u64 parent_length;
	u64 offset;
	u64 length;

	rbd_assert(img_request_child_test(img_request));

	/* First get what we need from the image request */

	pages = img_request->copyup_pages;
	rbd_assert(pages != NULL);
	img_request->copyup_pages = NULL;
	page_count = img_request->copyup_page_count;
	rbd_assert(page_count);
	img_request->copyup_page_count = 0;

	orig_request = img_request->obj_request;
	rbd_assert(orig_request != NULL);
	rbd_assert(obj_request_type_valid(orig_request->type));
	img_result = img_request->result;
	parent_length = img_request->length;
	rbd_assert(parent_length == img_request->xferred);
	rbd_img_request_put(img_request);

	rbd_assert(orig_request->img_request);
	rbd_dev = orig_request->img_request->rbd_dev;
	rbd_assert(rbd_dev);

	/*
	 * If the overlap has become 0 (most likely because the
	 * image has been flattened) we need to free the pages
	 * and re-submit the original write request.
	 */
	if (!rbd_dev->parent_overlap) {
		struct ceph_osd_client *osdc;

		ceph_release_page_vector(pages, page_count);
		osdc = &rbd_dev->rbd_client->client->osdc;
		img_result = rbd_obj_request_submit(osdc, orig_request);
		if (!img_result)
			return;
	}

	if (img_result)
		goto out_err;

	/*
	 * The original osd request is of no use to use any more.
	 * We need a new one that can hold the two ops in a copyup
	 * request.  Allocate the new copyup osd request for the
	 * original request, and release the old one.
	 */
	img_result = -ENOMEM;
	osd_req = rbd_osd_req_create_copyup(orig_request);
	if (!osd_req)
		goto out_err;
	rbd_osd_req_destroy(orig_request->osd_req);
	orig_request->osd_req = osd_req;
	orig_request->copyup_pages = pages;
	orig_request->copyup_page_count = page_count;

	/* Initialize the copyup op */

	osd_req_op_cls_init(osd_req, 0, CEPH_OSD_OP_CALL, "rbd", "copyup");
	osd_req_op_cls_request_data_pages(osd_req, 0, pages, parent_length, 0,
						false, false);

	/* Then the original write request op */

	offset = orig_request->offset;
	length = orig_request->length;
	osd_req_op_extent_init(osd_req, 1, CEPH_OSD_OP_WRITE,
					offset, length, 0, 0);
	if (orig_request->type == OBJ_REQUEST_BIO)
		osd_req_op_extent_osd_data_bio(osd_req, 1,
					orig_request->bio_list, length);
	else
		osd_req_op_extent_osd_data_pages(osd_req, 1,
					orig_request->pages, length,
					offset & ~PAGE_MASK, false, false);

	rbd_osd_req_format_write(orig_request);

	/* All set, send it off. */

	orig_request->callback = rbd_img_obj_copyup_callback;
	osdc = &rbd_dev->rbd_client->client->osdc;
	img_result = rbd_obj_request_submit(osdc, orig_request);
	if (!img_result)
		return;
out_err:
	/* Record the error code and complete the request */

	orig_request->result = img_result;
	orig_request->xferred = 0;
	obj_request_done_set(orig_request);
	rbd_obj_request_complete(orig_request);
}

/*
 * Read from the parent image the range of data that covers the
 * entire target of the given object request.  This is used for
 * satisfying a layered image write request when the target of an
 * object request from the image request does not exist.
 *
 * A page array big enough to hold the returned data is allocated
 * and supplied to rbd_img_request_fill() as the "data descriptor."
 * When the read completes, this page array will be transferred to
 * the original object request for the copyup operation.
 *
 * If an error occurs, record it as the result of the original
 * object request and mark it done so it gets completed.
 */
static int rbd_img_obj_parent_read_full(struct rbd_obj_request *obj_request)
{
	struct rbd_img_request *img_request = NULL;
	struct rbd_img_request *parent_request = NULL;
	struct rbd_device *rbd_dev;
	u64 img_offset;
	u64 length;
	struct page **pages = NULL;
	u32 page_count;
	int result;

	rbd_assert(obj_request_img_data_test(obj_request));
	rbd_assert(obj_request_type_valid(obj_request->type));

	img_request = obj_request->img_request;
	rbd_assert(img_request != NULL);
	rbd_dev = img_request->rbd_dev;
	rbd_assert(rbd_dev->parent != NULL);

	/*
	 * Determine the byte range covered by the object in the
	 * child image to which the original request was to be sent.
	 */
	img_offset = obj_request->img_offset - obj_request->offset;
	length = (u64)1 << rbd_dev->header.obj_order;

	/*
	 * There is no defined parent data beyond the parent
	 * overlap, so limit what we read at that boundary if
	 * necessary.
	 */
	if (img_offset + length > rbd_dev->parent_overlap) {
		rbd_assert(img_offset < rbd_dev->parent_overlap);
		length = rbd_dev->parent_overlap - img_offset;
	}

	/*
	 * Allocate a page array big enough to receive the data read
	 * from the parent.
	 */
	page_count = (u32)calc_pages_for(0, length);
	pages = ceph_alloc_page_vector(page_count, GFP_KERNEL);
	if (IS_ERR(pages)) {
		result = PTR_ERR(pages);
		pages = NULL;
		goto out_err;
	}

	result = -ENOMEM;
	parent_request = rbd_parent_request_create(obj_request,
						img_offset, length);
	if (!parent_request)
		goto out_err;

	result = rbd_img_request_fill(parent_request, OBJ_REQUEST_PAGES, pages);
	if (result)
		goto out_err;
	parent_request->copyup_pages = pages;
	parent_request->copyup_page_count = page_count;

	parent_request->callback = rbd_img_obj_parent_read_full_callback;
	result = rbd_img_request_submit(parent_request);
	if (!result)
		return 0;

	parent_request->copyup_pages = NULL;
	parent_request->copyup_page_count = 0;
	parent_request->obj_request = NULL;
	rbd_obj_request_put(obj_request);
out_err:
	if (pages)
		ceph_release_page_vector(pages, page_count);
	if (parent_request)
		rbd_img_request_put(parent_request);
	obj_request->result = result;
	obj_request->xferred = 0;
	obj_request_done_set(obj_request);

	return result;
}

static void rbd_img_obj_exists_callback(struct rbd_obj_request *obj_request)
{
	struct rbd_obj_request *orig_request;
	struct rbd_device *rbd_dev;
	int result;

	rbd_assert(!obj_request_img_data_test(obj_request));

	/*
	 * All we need from the object request is the original
	 * request and the result of the STAT op.  Grab those, then
	 * we're done with the request.
	 */
	orig_request = obj_request->obj_request;
	obj_request->obj_request = NULL;
	rbd_obj_request_put(orig_request);
	rbd_assert(orig_request);
	rbd_assert(orig_request->img_request);

	result = obj_request->result;
	obj_request->result = 0;

	dout("%s: obj %p for obj %p result %d %llu/%llu\n", __func__,
		obj_request, orig_request, result,
		obj_request->xferred, obj_request->length);
	rbd_obj_request_put(obj_request);

	/*
	 * If the overlap has become 0 (most likely because the
	 * image has been flattened) we need to free the pages
	 * and re-submit the original write request.
	 */
	rbd_dev = orig_request->img_request->rbd_dev;
	if (!rbd_dev->parent_overlap) {
		struct ceph_osd_client *osdc;

		osdc = &rbd_dev->rbd_client->client->osdc;
		result = rbd_obj_request_submit(osdc, orig_request);
		if (!result)
			return;
	}

	/*
	 * Our only purpose here is to determine whether the object
	 * exists, and we don't want to treat the non-existence as
	 * an error.  If something else comes back, transfer the
	 * error to the original request and complete it now.
	 */
	if (!result) {
		obj_request_existence_set(orig_request, true);
	} else if (result == -ENOENT) {
		obj_request_existence_set(orig_request, false);
	} else if (result) {
		orig_request->result = result;
		goto out;
	}

	/*
	 * Resubmit the original request now that we have recorded
	 * whether the target object exists.
	 */
	orig_request->result = rbd_img_obj_request_submit(orig_request);
out:
	if (orig_request->result)
		rbd_obj_request_complete(orig_request);
}

static int rbd_img_obj_exists_submit(struct rbd_obj_request *obj_request)
{
	struct rbd_obj_request *stat_request;
	struct rbd_device *rbd_dev;
	struct ceph_osd_client *osdc;
	struct page **pages = NULL;
	u32 page_count;
	size_t size;
	int ret;

	/*
	 * The response data for a STAT call consists of:
	 *     le64 length;
	 *     struct {
	 *         le32 tv_sec;
	 *         le32 tv_nsec;
	 *     } mtime;
	 */
	size = sizeof (__le64) + sizeof (__le32) + sizeof (__le32);
	page_count = (u32)calc_pages_for(0, size);
	pages = ceph_alloc_page_vector(page_count, GFP_KERNEL);
	if (IS_ERR(pages))
		return PTR_ERR(pages);

	ret = -ENOMEM;
	stat_request = rbd_obj_request_create(obj_request->object_name, 0, 0,
							OBJ_REQUEST_PAGES);
	if (!stat_request)
		goto out;

	rbd_obj_request_get(obj_request);
	stat_request->obj_request = obj_request;
	stat_request->pages = pages;
	stat_request->page_count = page_count;

	rbd_assert(obj_request->img_request);
	rbd_dev = obj_request->img_request->rbd_dev;
	stat_request->osd_req = rbd_osd_req_create(rbd_dev, false,
						stat_request);
	if (!stat_request->osd_req)
		goto out;
	stat_request->callback = rbd_img_obj_exists_callback;

	osd_req_op_init(stat_request->osd_req, 0, CEPH_OSD_OP_STAT);
	osd_req_op_raw_data_in_pages(stat_request->osd_req, 0, pages, size, 0,
					false, false);
	rbd_osd_req_format_read(stat_request);

	osdc = &rbd_dev->rbd_client->client->osdc;
	ret = rbd_obj_request_submit(osdc, stat_request);
out:
	if (ret)
		rbd_obj_request_put(obj_request);

	return ret;
}

static int rbd_img_obj_request_submit(struct rbd_obj_request *obj_request)
{
	struct rbd_img_request *img_request;
	struct rbd_device *rbd_dev;
	bool known;

	rbd_assert(obj_request_img_data_test(obj_request));

	img_request = obj_request->img_request;
	rbd_assert(img_request);
	rbd_dev = img_request->rbd_dev;

	/*
	 * Only writes to layered images need special handling.
	 * Reads and non-layered writes are simple object requests.
	 * Layered writes that start beyond the end of the overlap
	 * with the parent have no parent data, so they too are
	 * simple object requests.  Finally, if the target object is
	 * known to already exist, its parent data has already been
	 * copied, so a write to the object can also be handled as a
	 * simple object request.
	 */
	if (!img_request_write_test(img_request) ||
		!img_request_layered_test(img_request) ||
		!obj_request_overlaps_parent(obj_request) ||
		((known = obj_request_known_test(obj_request)) &&
			obj_request_exists_test(obj_request))) {

		struct rbd_device *rbd_dev;
		struct ceph_osd_client *osdc;

		rbd_dev = obj_request->img_request->rbd_dev;
		osdc = &rbd_dev->rbd_client->client->osdc;

		return rbd_obj_request_submit(osdc, obj_request);
	}

	/*
	 * It's a layered write.  The target object might exist but
	 * we may not know that yet.  If we know it doesn't exist,
	 * start by reading the data for the full target object from
	 * the parent so we can use it for a copyup to the target.
	 */
	if (known)
		return rbd_img_obj_parent_read_full(obj_request);

	/* We don't know whether the target exists.  Go find out. */

	return rbd_img_obj_exists_submit(obj_request);
}

static int rbd_img_request_submit(struct rbd_img_request *img_request)
{
	struct rbd_obj_request *obj_request;
	struct rbd_obj_request *next_obj_request;

	dout("%s: img %p\n", __func__, img_request);
	for_each_obj_request_safe(img_request, obj_request, next_obj_request) {
		int ret;

		ret = rbd_img_obj_request_submit(obj_request);
		if (ret)
			return ret;
	}

	return 0;
}

static void rbd_img_parent_read_callback(struct rbd_img_request *img_request)
{
	struct rbd_obj_request *obj_request;
	struct rbd_device *rbd_dev;
	u64 obj_end;
	u64 img_xferred;
	int img_result;

	rbd_assert(img_request_child_test(img_request));

	/* First get what we need from the image request and release it */

	obj_request = img_request->obj_request;
	img_xferred = img_request->xferred;
	img_result = img_request->result;
	rbd_img_request_put(img_request);

	/*
	 * If the overlap has become 0 (most likely because the
	 * image has been flattened) we need to re-submit the
	 * original request.
	 */
	rbd_assert(obj_request);
	rbd_assert(obj_request->img_request);
	rbd_dev = obj_request->img_request->rbd_dev;
	if (!rbd_dev->parent_overlap) {
		struct ceph_osd_client *osdc;

		osdc = &rbd_dev->rbd_client->client->osdc;
		img_result = rbd_obj_request_submit(osdc, obj_request);
		if (!img_result)
			return;
	}

	obj_request->result = img_result;
	if (obj_request->result)
		goto out;

	/*
	 * We need to zero anything beyond the parent overlap
	 * boundary.  Since rbd_img_obj_request_read_callback()
	 * will zero anything beyond the end of a short read, an
	 * easy way to do this is to pretend the data from the
	 * parent came up short--ending at the overlap boundary.
	 */
	rbd_assert(obj_request->img_offset < U64_MAX - obj_request->length);
	obj_end = obj_request->img_offset + obj_request->length;
	if (obj_end > rbd_dev->parent_overlap) {
		u64 xferred = 0;

		if (obj_request->img_offset < rbd_dev->parent_overlap)
			xferred = rbd_dev->parent_overlap -
					obj_request->img_offset;

		obj_request->xferred = min(img_xferred, xferred);
	} else {
		obj_request->xferred = img_xferred;
	}
out:
	rbd_img_obj_request_read_callback(obj_request);
	rbd_obj_request_complete(obj_request);
}

static void rbd_img_parent_read(struct rbd_obj_request *obj_request)
{
	struct rbd_img_request *img_request;
	int result;

	rbd_assert(obj_request_img_data_test(obj_request));
	rbd_assert(obj_request->img_request != NULL);
	rbd_assert(obj_request->result == (s32) -ENOENT);
	rbd_assert(obj_request_type_valid(obj_request->type));

	/* rbd_read_finish(obj_request, obj_request->length); */
	img_request = rbd_parent_request_create(obj_request,
						obj_request->img_offset,
						obj_request->length);
	result = -ENOMEM;
	if (!img_request)
		goto out_err;

	if (obj_request->type == OBJ_REQUEST_BIO)
		result = rbd_img_request_fill(img_request, OBJ_REQUEST_BIO,
						obj_request->bio_list);
	else
		result = rbd_img_request_fill(img_request, OBJ_REQUEST_PAGES,
						obj_request->pages);
	if (result)
		goto out_err;

	img_request->callback = rbd_img_parent_read_callback;
	result = rbd_img_request_submit(img_request);
	if (result)
		goto out_err;

	return;
out_err:
	if (img_request)
		rbd_img_request_put(img_request);
	obj_request->result = result;
	obj_request->xferred = 0;
	obj_request_done_set(obj_request);
}

static int rbd_obj_notify_ack_sync(struct rbd_device *rbd_dev, u64 notify_id)
{
	struct rbd_obj_request *obj_request;
	struct ceph_osd_client *osdc = &rbd_dev->rbd_client->client->osdc;
	int ret;

	obj_request = rbd_obj_request_create(rbd_dev->header_name, 0, 0,
							OBJ_REQUEST_NODATA);
	if (!obj_request)
		return -ENOMEM;

	ret = -ENOMEM;
	obj_request->osd_req = rbd_osd_req_create(rbd_dev, false, obj_request);
	if (!obj_request->osd_req)
		goto out;

	osd_req_op_watch_init(obj_request->osd_req, 0, CEPH_OSD_OP_NOTIFY_ACK,
					notify_id, 0, 0);
	rbd_osd_req_format_read(obj_request);

	ret = rbd_obj_request_submit(osdc, obj_request);
	if (ret)
		goto out;
	ret = rbd_obj_request_wait(obj_request);
out:
	rbd_obj_request_put(obj_request);

	return ret;
}

static void rbd_watch_cb(u64 ver, u64 notify_id, u8 opcode, void *data)
{
	struct rbd_device *rbd_dev = (struct rbd_device *)data;
	int ret;

	if (!rbd_dev)
		return;

	dout("%s: \"%s\" notify_id %llu opcode %u\n", __func__,
		rbd_dev->header_name, (unsigned long long)notify_id,
		(unsigned int)opcode);
	ret = rbd_dev_refresh(rbd_dev);
	if (ret)
		rbd_warn(rbd_dev, "header refresh error (%d)\n", ret);

	rbd_obj_notify_ack_sync(rbd_dev, notify_id);
}

/*
 * Request sync osd watch/unwatch.  The value of "start" determines
 * whether a watch request is being initiated or torn down.
 */
static int rbd_dev_header_watch_sync(struct rbd_device *rbd_dev, bool start)
{
	struct ceph_osd_client *osdc = &rbd_dev->rbd_client->client->osdc;
	struct rbd_obj_request *obj_request;
	int ret;

	rbd_assert(start ^ !!rbd_dev->watch_event);
	rbd_assert(start ^ !!rbd_dev->watch_request);

	if (start) {
		ret = ceph_osdc_create_event(osdc, rbd_watch_cb, rbd_dev,
						&rbd_dev->watch_event);
		if (ret < 0)
			return ret;
		rbd_assert(rbd_dev->watch_event != NULL);
	}

	ret = -ENOMEM;
	obj_request = rbd_obj_request_create(rbd_dev->header_name, 0, 0,
							OBJ_REQUEST_NODATA);
	if (!obj_request)
		goto out_cancel;

	obj_request->osd_req = rbd_osd_req_create(rbd_dev, true, obj_request);
	if (!obj_request->osd_req)
		goto out_cancel;

	if (start)
		ceph_osdc_set_request_linger(osdc, obj_request->osd_req);
	else
		ceph_osdc_unregister_linger_request(osdc,
					rbd_dev->watch_request->osd_req);

	osd_req_op_watch_init(obj_request->osd_req, 0, CEPH_OSD_OP_WATCH,
				rbd_dev->watch_event->cookie, 0, start ? 1 : 0);
	rbd_osd_req_format_write(obj_request);

	ret = rbd_obj_request_submit(osdc, obj_request);
	if (ret)
		goto out_cancel;
	ret = rbd_obj_request_wait(obj_request);
	if (ret)
		goto out_cancel;
	ret = obj_request->result;
	if (ret)
		goto out_cancel;

	/*
	 * A watch request is set to linger, so the underlying osd
	 * request won't go away until we unregister it.  We retain
	 * a pointer to the object request during that time (in
	 * rbd_dev->watch_request), so we'll keep a reference to
	 * it.  We'll drop that reference (below) after we've
	 * unregistered it.
	 */
	if (start) {
		rbd_dev->watch_request = obj_request;

		return 0;
	}

	/* We have successfully torn down the watch request */

	rbd_obj_request_put(rbd_dev->watch_request);
	rbd_dev->watch_request = NULL;
out_cancel:
	/* Cancel the event if we're tearing down, or on error */
	ceph_osdc_cancel_event(rbd_dev->watch_event);
	rbd_dev->watch_event = NULL;
	if (obj_request)
		rbd_obj_request_put(obj_request);

	return ret;
}

/*
 * Synchronous osd object method call.  Returns the number of bytes
 * returned in the outbound buffer, or a negative error code.
 */
static int rbd_obj_method_sync(struct rbd_device *rbd_dev,
			     const char *object_name,
			     const char *class_name,
			     const char *method_name,
			     const void *outbound,
			     size_t outbound_size,
			     void *inbound,
			     size_t inbound_size)
{
	struct ceph_osd_client *osdc = &rbd_dev->rbd_client->client->osdc;
	struct rbd_obj_request *obj_request;
	struct page **pages;
	u32 page_count;
	int ret;

	/*
	 * Method calls are ultimately read operations.  The result
	 * should placed into the inbound buffer provided.  They
	 * also supply outbound data--parameters for the object
	 * method.  Currently if this is present it will be a
	 * snapshot id.
	 */
	page_count = (u32)calc_pages_for(0, inbound_size);
	pages = ceph_alloc_page_vector(page_count, GFP_KERNEL);
	if (IS_ERR(pages))
		return PTR_ERR(pages);

	ret = -ENOMEM;
	obj_request = rbd_obj_request_create(object_name, 0, inbound_size,
							OBJ_REQUEST_PAGES);
	if (!obj_request)
		goto out;

	obj_request->pages = pages;
	obj_request->page_count = page_count;

	obj_request->osd_req = rbd_osd_req_create(rbd_dev, false, obj_request);
	if (!obj_request->osd_req)
		goto out;

	osd_req_op_cls_init(obj_request->osd_req, 0, CEPH_OSD_OP_CALL,
					class_name, method_name);
	if (outbound_size) {
		struct ceph_pagelist *pagelist;

		pagelist = kmalloc(sizeof (*pagelist), GFP_NOFS);
		if (!pagelist)
			goto out;

		ceph_pagelist_init(pagelist);
		ceph_pagelist_append(pagelist, outbound, outbound_size);
		osd_req_op_cls_request_data_pagelist(obj_request->osd_req, 0,
						pagelist);
	}
	osd_req_op_cls_response_data_pages(obj_request->osd_req, 0,
					obj_request->pages, inbound_size,
					0, false, false);
	rbd_osd_req_format_read(obj_request);

	ret = rbd_obj_request_submit(osdc, obj_request);
	if (ret)
		goto out;
	ret = rbd_obj_request_wait(obj_request);
	if (ret)
		goto out;

	ret = obj_request->result;
	if (ret < 0)
		goto out;

	rbd_assert(obj_request->xferred < (u64)INT_MAX);
	ret = (int)obj_request->xferred;
	ceph_copy_from_page_vector(pages, inbound, 0, obj_request->xferred);
out:
	if (obj_request)
		rbd_obj_request_put(obj_request);
	else
		ceph_release_page_vector(pages, page_count);

	return ret;
}

static void rbd_request_fn(struct request_queue *q)
		__releases(q->queue_lock) __acquires(q->queue_lock)
{
	struct rbd_device *rbd_dev = q->queuedata;
	bool read_only = rbd_dev->mapping.read_only;
	struct request *rq;
	int result;

	while ((rq = blk_fetch_request(q))) {
		bool write_request = rq_data_dir(rq) == WRITE;
		struct rbd_img_request *img_request;
		u64 offset;
		u64 length;

		/* Ignore any non-FS requests that filter through. */

		if (rq->cmd_type != REQ_TYPE_FS) {
			dout("%s: non-fs request type %d\n", __func__,
				(int) rq->cmd_type);
			__blk_end_request_all(rq, 0);
			continue;
		}

		/* Ignore/skip any zero-length requests */

		offset = (u64) blk_rq_pos(rq) << SECTOR_SHIFT;
		length = (u64) blk_rq_bytes(rq);

		if (!length) {
			dout("%s: zero-length request\n", __func__);
			__blk_end_request_all(rq, 0);
			continue;
		}

		spin_unlock_irq(q->queue_lock);

		/* Disallow writes to a read-only device */

		if (write_request) {
			result = -EROFS;
			if (read_only)
				goto end_request;
			rbd_assert(rbd_dev->spec->snap_id == CEPH_NOSNAP);
		}

		/*
		 * Quit early if the mapped snapshot no longer
		 * exists.  It's still possible the snapshot will
		 * have disappeared by the time our request arrives
		 * at the osd, but there's no sense in sending it if
		 * we already know.
		 */
		if (!test_bit(RBD_DEV_FLAG_EXISTS, &rbd_dev->flags)) {
			dout("request for non-existent snapshot");
			rbd_assert(rbd_dev->spec->snap_id != CEPH_NOSNAP);
			result = -ENXIO;
			goto end_request;
		}

		result = -EINVAL;
		if (offset && length > U64_MAX - offset + 1) {
			rbd_warn(rbd_dev, "bad request range (%llu~%llu)\n",
				offset, length);
			goto end_request;	/* Shouldn't happen */
		}

		result = -EIO;
		if (offset + length > rbd_dev->mapping.size) {
			rbd_warn(rbd_dev, "beyond EOD (%llu~%llu > %llu)\n",
				offset, length, rbd_dev->mapping.size);
			goto end_request;
		}

		result = -ENOMEM;
		img_request = rbd_img_request_create(rbd_dev, offset, length,
							write_request);
		if (!img_request)
			goto end_request;

		img_request->rq = rq;

		result = rbd_img_request_fill(img_request, OBJ_REQUEST_BIO,
						rq->bio);
		if (!result)
			result = rbd_img_request_submit(img_request);
		if (result)
			rbd_img_request_put(img_request);
end_request:
		spin_lock_irq(q->queue_lock);
		if (result < 0) {
			rbd_warn(rbd_dev, "%s %llx at %llx result %d\n",
				write_request ? "write" : "read",
				length, offset, result);

			__blk_end_request_all(rq, result);
		}
	}
}

/*
 * a queue callback. Makes sure that we don't create a bio that spans across
 * multiple osd objects. One exception would be with a single page bios,
 * which we handle later at bio_chain_clone_range()
 */
static int rbd_merge_bvec(struct request_queue *q, struct bvec_merge_data *bmd,
			  struct bio_vec *bvec)
{
	struct rbd_device *rbd_dev = q->queuedata;
	sector_t sector_offset;
	sector_t sectors_per_obj;
	sector_t obj_sector_offset;
	int ret;

	/*
	 * Find how far into its rbd object the partition-relative
	 * bio start sector is to offset relative to the enclosing
	 * device.
	 */
	sector_offset = get_start_sect(bmd->bi_bdev) + bmd->bi_sector;
	sectors_per_obj = 1 << (rbd_dev->header.obj_order - SECTOR_SHIFT);
	obj_sector_offset = sector_offset & (sectors_per_obj - 1);

	/*
	 * Compute the number of bytes from that offset to the end
	 * of the object.  Account for what's already used by the bio.
	 */
	ret = (int) (sectors_per_obj - obj_sector_offset) << SECTOR_SHIFT;
	if (ret > bmd->bi_size)
		ret -= bmd->bi_size;
	else
		ret = 0;

	/*
	 * Don't send back more than was asked for.  And if the bio
	 * was empty, let the whole thing through because:  "Note
	 * that a block device *must* allow a single page to be
	 * added to an empty bio."
	 */
	rbd_assert(bvec->bv_len <= PAGE_SIZE);
	if (ret > (int) bvec->bv_len || !bmd->bi_size)
		ret = (int) bvec->bv_len;

	return ret;
}

static void rbd_free_disk(struct rbd_device *rbd_dev)
{
	struct gendisk *disk = rbd_dev->disk;

	if (!disk)
		return;

	rbd_dev->disk = NULL;
	if (disk->flags & GENHD_FL_UP) {
		del_gendisk(disk);
		if (disk->queue)
			blk_cleanup_queue(disk->queue);
	}
	put_disk(disk);
}

static int rbd_obj_read_sync(struct rbd_device *rbd_dev,
				const char *object_name,
				u64 offset, u64 length, void *buf)

{
	struct ceph_osd_client *osdc = &rbd_dev->rbd_client->client->osdc;
	struct rbd_obj_request *obj_request;
	struct page **pages = NULL;
	u32 page_count;
	size_t size;
	int ret;

	page_count = (u32) calc_pages_for(offset, length);
	pages = ceph_alloc_page_vector(page_count, GFP_KERNEL);
	if (IS_ERR(pages))
		return PTR_ERR(pages);

	ret = -ENOMEM;
	obj_request = rbd_obj_request_create(object_name, offset, length,
							OBJ_REQUEST_PAGES);
	if (!obj_request)
		goto out;

	obj_request->pages = pages;
	obj_request->page_count = page_count;

	obj_request->osd_req = rbd_osd_req_create(rbd_dev, false, obj_request);
	if (!obj_request->osd_req)
		goto out;

	osd_req_op_extent_init(obj_request->osd_req, 0, CEPH_OSD_OP_READ,
					offset, length, 0, 0);
	osd_req_op_extent_osd_data_pages(obj_request->osd_req, 0,
					obj_request->pages,
					obj_request->length,
					obj_request->offset & ~PAGE_MASK,
					false, false);
	rbd_osd_req_format_read(obj_request);

	ret = rbd_obj_request_submit(osdc, obj_request);
	if (ret)
		goto out;
	ret = rbd_obj_request_wait(obj_request);
	if (ret)
		goto out;

	ret = obj_request->result;
	if (ret < 0)
		goto out;

	rbd_assert(obj_request->xferred <= (u64) SIZE_MAX);
	size = (size_t) obj_request->xferred;
	ceph_copy_from_page_vector(pages, buf, 0, size);
	rbd_assert(size <= (size_t)INT_MAX);
	ret = (int)size;
out:
	if (obj_request)
		rbd_obj_request_put(obj_request);
	else
		ceph_release_page_vector(pages, page_count);

	return ret;
}

/*
 * Read the complete header for the given rbd device.  On successful
 * return, the rbd_dev->header field will contain up-to-date
 * information about the image.
 */
static int rbd_dev_v1_header_info(struct rbd_device *rbd_dev)
{
	struct rbd_image_header_ondisk *ondisk = NULL;
	u32 snap_count = 0;
	u64 names_size = 0;
	u32 want_count;
	int ret;

	/*
	 * The complete header will include an array of its 64-bit
	 * snapshot ids, followed by the names of those snapshots as
	 * a contiguous block of NUL-terminated strings.  Note that
	 * the number of snapshots could change by the time we read
	 * it in, in which case we re-read it.
	 */
	do {
		size_t size;

		kfree(ondisk);

		size = sizeof (*ondisk);
		size += snap_count * sizeof (struct rbd_image_snap_ondisk);
		size += names_size;
		ondisk = kmalloc(size, GFP_KERNEL);
		if (!ondisk)
			return -ENOMEM;

		ret = rbd_obj_read_sync(rbd_dev, rbd_dev->header_name,
				       0, size, ondisk);
		if (ret < 0)
			goto out;
		if ((size_t)ret < size) {
			ret = -ENXIO;
			rbd_warn(rbd_dev, "short header read (want %zd got %d)",
				size, ret);
			goto out;
		}
		if (!rbd_dev_ondisk_valid(ondisk)) {
			ret = -ENXIO;
			rbd_warn(rbd_dev, "invalid header");
			goto out;
		}

		names_size = le64_to_cpu(ondisk->snap_names_len);
		want_count = snap_count;
		snap_count = le32_to_cpu(ondisk->snap_count);
	} while (snap_count != want_count);

	ret = rbd_header_from_disk(rbd_dev, ondisk);
out:
	kfree(ondisk);

	return ret;
}

/*
 * Clear the rbd device's EXISTS flag if the snapshot it's mapped to
 * has disappeared from the (just updated) snapshot context.
 */
static void rbd_exists_validate(struct rbd_device *rbd_dev)
{
	u64 snap_id;

	if (!test_bit(RBD_DEV_FLAG_EXISTS, &rbd_dev->flags))
		return;

	snap_id = rbd_dev->spec->snap_id;
	if (snap_id == CEPH_NOSNAP)
		return;

	if (rbd_dev_snap_index(rbd_dev, snap_id) == BAD_SNAP_INDEX)
		clear_bit(RBD_DEV_FLAG_EXISTS, &rbd_dev->flags);
}

static void rbd_dev_update_size(struct rbd_device *rbd_dev)
{
	sector_t size;
	bool removing;

	/*
	 * Don't hold the lock while doing disk operations,
	 * or lock ordering will conflict with the bdev mutex via:
	 * rbd_add() -> blkdev_get() -> rbd_open()
	 */
	spin_lock_irq(&rbd_dev->lock);
	removing = test_bit(RBD_DEV_FLAG_REMOVING, &rbd_dev->flags);
	spin_unlock_irq(&rbd_dev->lock);
	/*
	 * If the device is being removed, rbd_dev->disk has
	 * been destroyed, so don't try to update its size
	 */
	if (!removing) {
		size = (sector_t)rbd_dev->mapping.size / SECTOR_SIZE;
		dout("setting size to %llu sectors", (unsigned long long)size);
		set_capacity(rbd_dev->disk, size);
		revalidate_disk(rbd_dev->disk);
	}
}

static int rbd_dev_refresh(struct rbd_device *rbd_dev)
{
	u64 mapping_size;
	int ret;

	rbd_assert(rbd_image_format_valid(rbd_dev->image_format));
	down_write(&rbd_dev->header_rwsem);
	mapping_size = rbd_dev->mapping.size;
	if (rbd_dev->image_format == 1)
		ret = rbd_dev_v1_header_info(rbd_dev);
	else
		ret = rbd_dev_v2_header_info(rbd_dev);

	/* If it's a mapped snapshot, validate its EXISTS flag */

	rbd_exists_validate(rbd_dev);
	up_write(&rbd_dev->header_rwsem);

	if (mapping_size != rbd_dev->mapping.size) {
		rbd_dev_update_size(rbd_dev);
	}

	return ret;
}

static int rbd_init_disk(struct rbd_device *rbd_dev)
{
	struct gendisk *disk;
	struct request_queue *q;
	u64 segment_size;

	/* create gendisk info */
	disk = alloc_disk(RBD_MINORS_PER_MAJOR);
	if (!disk)
		return -ENOMEM;

	snprintf(disk->disk_name, sizeof(disk->disk_name), RBD_DRV_NAME "%d",
		 rbd_dev->dev_id);
	disk->major = rbd_dev->major;
	disk->first_minor = 0;
	disk->fops = &rbd_bd_ops;
	disk->private_data = rbd_dev;

	q = blk_init_queue(rbd_request_fn, &rbd_dev->lock);
	if (!q)
		goto out_disk;

	/* We use the default size, but let's be explicit about it. */
	blk_queue_physical_block_size(q, SECTOR_SIZE);

	/* set io sizes to object size */
	segment_size = rbd_obj_bytes(&rbd_dev->header);
	blk_queue_max_hw_sectors(q, segment_size / SECTOR_SIZE);
	blk_queue_max_segment_size(q, segment_size);
	blk_queue_io_min(q, segment_size);
	blk_queue_io_opt(q, segment_size);

	blk_queue_merge_bvec(q, rbd_merge_bvec);
	disk->queue = q;

	q->queuedata = rbd_dev;

	rbd_dev->disk = disk;

	return 0;
out_disk:
	put_disk(disk);

	return -ENOMEM;
}

/*
  sysfs
*/

static struct rbd_device *dev_to_rbd_dev(struct device *dev)
{
	return container_of(dev, struct rbd_device, dev);
}

static ssize_t rbd_size_show(struct device *dev,
			     struct device_attribute *attr, char *buf)
{
	struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);

	return sprintf(buf, "%llu\n",
		(unsigned long long)rbd_dev->mapping.size);
}

/*
 * Note this shows the features for whatever's mapped, which is not
 * necessarily the base image.
 */
static ssize_t rbd_features_show(struct device *dev,
			     struct device_attribute *attr, char *buf)
{
	struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);

	return sprintf(buf, "0x%016llx\n",
			(unsigned long long)rbd_dev->mapping.features);
}

static ssize_t rbd_major_show(struct device *dev,
			      struct device_attribute *attr, char *buf)
{
	struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);

	if (rbd_dev->major)
		return sprintf(buf, "%d\n", rbd_dev->major);

	return sprintf(buf, "(none)\n");

}

static ssize_t rbd_client_id_show(struct device *dev,
				  struct device_attribute *attr, char *buf)
{
	struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);

	return sprintf(buf, "client%lld\n",
			ceph_client_id(rbd_dev->rbd_client->client));
}

static ssize_t rbd_pool_show(struct device *dev,
			     struct device_attribute *attr, char *buf)
{
	struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);

	return sprintf(buf, "%s\n", rbd_dev->spec->pool_name);
}

static ssize_t rbd_pool_id_show(struct device *dev,
			     struct device_attribute *attr, char *buf)
{
	struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);

	return sprintf(buf, "%llu\n",
			(unsigned long long) rbd_dev->spec->pool_id);
}

static ssize_t rbd_name_show(struct device *dev,
			     struct device_attribute *attr, char *buf)
{
	struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);

	if (rbd_dev->spec->image_name)
		return sprintf(buf, "%s\n", rbd_dev->spec->image_name);

	return sprintf(buf, "(unknown)\n");
}

static ssize_t rbd_image_id_show(struct device *dev,
			     struct device_attribute *attr, char *buf)
{
	struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);

	return sprintf(buf, "%s\n", rbd_dev->spec->image_id);
}

/*
 * Shows the name of the currently-mapped snapshot (or
 * RBD_SNAP_HEAD_NAME for the base image).
 */
static ssize_t rbd_snap_show(struct device *dev,
			     struct device_attribute *attr,
			     char *buf)
{
	struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);

	return sprintf(buf, "%s\n", rbd_dev->spec->snap_name);
}

/*
 * For an rbd v2 image, shows the pool id, image id, and snapshot id
 * for the parent image.  If there is no parent, simply shows
 * "(no parent image)".
 */
static ssize_t rbd_parent_show(struct device *dev,
			     struct device_attribute *attr,
			     char *buf)
{
	struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
	struct rbd_spec *spec = rbd_dev->parent_spec;
	int count;
	char *bufp = buf;

	if (!spec)
		return sprintf(buf, "(no parent image)\n");

	count = sprintf(bufp, "pool_id %llu\npool_name %s\n",
			(unsigned long long) spec->pool_id, spec->pool_name);
	if (count < 0)
		return count;
	bufp += count;

	count = sprintf(bufp, "image_id %s\nimage_name %s\n", spec->image_id,
			spec->image_name ? spec->image_name : "(unknown)");
	if (count < 0)
		return count;
	bufp += count;

	count = sprintf(bufp, "snap_id %llu\nsnap_name %s\n",
			(unsigned long long) spec->snap_id, spec->snap_name);
	if (count < 0)
		return count;
	bufp += count;

	count = sprintf(bufp, "overlap %llu\n", rbd_dev->parent_overlap);
	if (count < 0)
		return count;
	bufp += count;

	return (ssize_t) (bufp - buf);
}

static ssize_t rbd_image_refresh(struct device *dev,
				 struct device_attribute *attr,
				 const char *buf,
				 size_t size)
{
	struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
	int ret;

	ret = rbd_dev_refresh(rbd_dev);
	if (ret)
		rbd_warn(rbd_dev, ": manual header refresh error (%d)\n", ret);

	return ret < 0 ? ret : size;
}

static DEVICE_ATTR(size, S_IRUGO, rbd_size_show, NULL);
static DEVICE_ATTR(features, S_IRUGO, rbd_features_show, NULL);
static DEVICE_ATTR(major, S_IRUGO, rbd_major_show, NULL);
static DEVICE_ATTR(client_id, S_IRUGO, rbd_client_id_show, NULL);
static DEVICE_ATTR(pool, S_IRUGO, rbd_pool_show, NULL);
static DEVICE_ATTR(pool_id, S_IRUGO, rbd_pool_id_show, NULL);
static DEVICE_ATTR(name, S_IRUGO, rbd_name_show, NULL);
static DEVICE_ATTR(image_id, S_IRUGO, rbd_image_id_show, NULL);
static DEVICE_ATTR(refresh, S_IWUSR, NULL, rbd_image_refresh);
static DEVICE_ATTR(current_snap, S_IRUGO, rbd_snap_show, NULL);
static DEVICE_ATTR(parent, S_IRUGO, rbd_parent_show, NULL);

static struct attribute *rbd_attrs[] = {
	&dev_attr_size.attr,
	&dev_attr_features.attr,
	&dev_attr_major.attr,
	&dev_attr_client_id.attr,
	&dev_attr_pool.attr,
	&dev_attr_pool_id.attr,
	&dev_attr_name.attr,
	&dev_attr_image_id.attr,
	&dev_attr_current_snap.attr,
	&dev_attr_parent.attr,
	&dev_attr_refresh.attr,
	NULL
};

static struct attribute_group rbd_attr_group = {
	.attrs = rbd_attrs,
};

static const struct attribute_group *rbd_attr_groups[] = {
	&rbd_attr_group,
	NULL
};

static void rbd_sysfs_dev_release(struct device *dev)
{
}

static struct device_type rbd_device_type = {
	.name		= "rbd",
	.groups		= rbd_attr_groups,
	.release	= rbd_sysfs_dev_release,
};

static struct rbd_spec *rbd_spec_get(struct rbd_spec *spec)
{
	kref_get(&spec->kref);

	return spec;
}

static void rbd_spec_free(struct kref *kref);
static void rbd_spec_put(struct rbd_spec *spec)
{
	if (spec)
		kref_put(&spec->kref, rbd_spec_free);
}

static struct rbd_spec *rbd_spec_alloc(void)
{
	struct rbd_spec *spec;

	spec = kzalloc(sizeof (*spec), GFP_KERNEL);
	if (!spec)
		return NULL;
	kref_init(&spec->kref);

	return spec;
}

static void rbd_spec_free(struct kref *kref)
{
	struct rbd_spec *spec = container_of(kref, struct rbd_spec, kref);

	kfree(spec->pool_name);
	kfree(spec->image_id);
	kfree(spec->image_name);
	kfree(spec->snap_name);
	kfree(spec);
}

static struct rbd_device *rbd_dev_create(struct rbd_client *rbdc,
				struct rbd_spec *spec)
{
	struct rbd_device *rbd_dev;

	rbd_dev = kzalloc(sizeof (*rbd_dev), GFP_KERNEL);
	if (!rbd_dev)
		return NULL;

	spin_lock_init(&rbd_dev->lock);
	rbd_dev->flags = 0;
	atomic_set(&rbd_dev->parent_ref, 0);
	INIT_LIST_HEAD(&rbd_dev->node);
	init_rwsem(&rbd_dev->header_rwsem);

	rbd_dev->spec = spec;
	rbd_dev->rbd_client = rbdc;

	/* Initialize the layout used for all rbd requests */

	rbd_dev->layout.fl_stripe_unit = cpu_to_le32(1 << RBD_MAX_OBJ_ORDER);
	rbd_dev->layout.fl_stripe_count = cpu_to_le32(1);
	rbd_dev->layout.fl_object_size = cpu_to_le32(1 << RBD_MAX_OBJ_ORDER);
	rbd_dev->layout.fl_pg_pool = cpu_to_le32((u32) spec->pool_id);

	return rbd_dev;
}

static void rbd_dev_destroy(struct rbd_device *rbd_dev)
{
	rbd_put_client(rbd_dev->rbd_client);
	rbd_spec_put(rbd_dev->spec);
	kfree(rbd_dev);
}

/*
 * Get the size and object order for an image snapshot, or if
 * snap_id is CEPH_NOSNAP, gets this information for the base
 * image.
 */
static int _rbd_dev_v2_snap_size(struct rbd_device *rbd_dev, u64 snap_id,
				u8 *order, u64 *snap_size)
{
	__le64 snapid = cpu_to_le64(snap_id);
	int ret;
	struct {
		u8 order;
		__le64 size;
	} __attribute__ ((packed)) size_buf = { 0 };

	ret = rbd_obj_method_sync(rbd_dev, rbd_dev->header_name,
				"rbd", "get_size",
				&snapid, sizeof (snapid),
				&size_buf, sizeof (size_buf));
	dout("%s: rbd_obj_method_sync returned %d\n", __func__, ret);
	if (ret < 0)
		return ret;
	if (ret < sizeof (size_buf))
		return -ERANGE;

	if (order) {
		*order = size_buf.order;
		dout("  order %u", (unsigned int)*order);
	}
	*snap_size = le64_to_cpu(size_buf.size);

	dout("  snap_id 0x%016llx snap_size = %llu\n",
		(unsigned long long)snap_id,
		(unsigned long long)*snap_size);

	return 0;
}

static int rbd_dev_v2_image_size(struct rbd_device *rbd_dev)
{
	return _rbd_dev_v2_snap_size(rbd_dev, CEPH_NOSNAP,
					&rbd_dev->header.obj_order,
					&rbd_dev->header.image_size);
}

static int rbd_dev_v2_object_prefix(struct rbd_device *rbd_dev)
{
	void *reply_buf;
	int ret;
	void *p;

	reply_buf = kzalloc(RBD_OBJ_PREFIX_LEN_MAX, GFP_KERNEL);
	if (!reply_buf)
		return -ENOMEM;

	ret = rbd_obj_method_sync(rbd_dev, rbd_dev->header_name,
				"rbd", "get_object_prefix", NULL, 0,
				reply_buf, RBD_OBJ_PREFIX_LEN_MAX);
	dout("%s: rbd_obj_method_sync returned %d\n", __func__, ret);
	if (ret < 0)
		goto out;

	p = reply_buf;
	rbd_dev->header.object_prefix = ceph_extract_encoded_string(&p,
						p + ret, NULL, GFP_NOIO);
	ret = 0;

	if (IS_ERR(rbd_dev->header.object_prefix)) {
		ret = PTR_ERR(rbd_dev->header.object_prefix);
		rbd_dev->header.object_prefix = NULL;
	} else {
		dout("  object_prefix = %s\n", rbd_dev->header.object_prefix);
	}
out:
	kfree(reply_buf);

	return ret;
}

static int _rbd_dev_v2_snap_features(struct rbd_device *rbd_dev, u64 snap_id,
		u64 *snap_features)
{
	__le64 snapid = cpu_to_le64(snap_id);
	struct {
		__le64 features;
		__le64 incompat;
	} __attribute__ ((packed)) features_buf = { 0 };
	u64 incompat;
	int ret;

	ret = rbd_obj_method_sync(rbd_dev, rbd_dev->header_name,
				"rbd", "get_features",
				&snapid, sizeof (snapid),
				&features_buf, sizeof (features_buf));
	dout("%s: rbd_obj_method_sync returned %d\n", __func__, ret);
	if (ret < 0)
		return ret;
	if (ret < sizeof (features_buf))
		return -ERANGE;

	incompat = le64_to_cpu(features_buf.incompat);
	if (incompat & ~RBD_FEATURES_SUPPORTED)
		return -ENXIO;

	*snap_features = le64_to_cpu(features_buf.features);

	dout("  snap_id 0x%016llx features = 0x%016llx incompat = 0x%016llx\n",
		(unsigned long long)snap_id,
		(unsigned long long)*snap_features,
		(unsigned long long)le64_to_cpu(features_buf.incompat));

	return 0;
}

static int rbd_dev_v2_features(struct rbd_device *rbd_dev)
{
	return _rbd_dev_v2_snap_features(rbd_dev, CEPH_NOSNAP,
						&rbd_dev->header.features);
}

static int rbd_dev_v2_parent_info(struct rbd_device *rbd_dev)
{
	struct rbd_spec *parent_spec;
	size_t size;
	void *reply_buf = NULL;
	__le64 snapid;
	void *p;
	void *end;
	u64 pool_id;
	char *image_id;
	u64 snap_id;
	u64 overlap;
	int ret;

	parent_spec = rbd_spec_alloc();
	if (!parent_spec)
		return -ENOMEM;

	size = sizeof (__le64) +				/* pool_id */
		sizeof (__le32) + RBD_IMAGE_ID_LEN_MAX +	/* image_id */
		sizeof (__le64) +				/* snap_id */
		sizeof (__le64);				/* overlap */
	reply_buf = kmalloc(size, GFP_KERNEL);
	if (!reply_buf) {
		ret = -ENOMEM;
		goto out_err;
	}

	snapid = cpu_to_le64(CEPH_NOSNAP);
	ret = rbd_obj_method_sync(rbd_dev, rbd_dev->header_name,
				"rbd", "get_parent",
				&snapid, sizeof (snapid),
				reply_buf, size);
	dout("%s: rbd_obj_method_sync returned %d\n", __func__, ret);
	if (ret < 0)
		goto out_err;

	p = reply_buf;
	end = reply_buf + ret;
	ret = -ERANGE;
	ceph_decode_64_safe(&p, end, pool_id, out_err);
	if (pool_id == CEPH_NOPOOL) {
		/*
		 * Either the parent never existed, or we have
		 * record of it but the image got flattened so it no
		 * longer has a parent.  When the parent of a
		 * layered image disappears we immediately set the
		 * overlap to 0.  The effect of this is that all new
		 * requests will be treated as if the image had no
		 * parent.
		 */
		if (rbd_dev->parent_overlap) {
			rbd_dev->parent_overlap = 0;
			smp_mb();
			rbd_dev_parent_put(rbd_dev);
			pr_info("%s: clone image has been flattened\n",
				rbd_dev->disk->disk_name);
		}

		goto out;	/* No parent?  No problem. */
	}

	/* The ceph file layout needs to fit pool id in 32 bits */

	ret = -EIO;
	if (pool_id > (u64)U32_MAX) {
		rbd_warn(NULL, "parent pool id too large (%llu > %u)\n",
			(unsigned long long)pool_id, U32_MAX);
		goto out_err;
	}

	image_id = ceph_extract_encoded_string(&p, end, NULL, GFP_KERNEL);
	if (IS_ERR(image_id)) {
		ret = PTR_ERR(image_id);
		goto out_err;
	}
	ceph_decode_64_safe(&p, end, snap_id, out_err);
	ceph_decode_64_safe(&p, end, overlap, out_err);

	/*
	 * The parent won't change (except when the clone is
	 * flattened, already handled that).  So we only need to
	 * record the parent spec we have not already done so.
	 */
	if (!rbd_dev->parent_spec) {
		parent_spec->pool_id = pool_id;
		parent_spec->image_id = image_id;
		parent_spec->snap_id = snap_id;
		rbd_dev->parent_spec = parent_spec;
		parent_spec = NULL;	/* rbd_dev now owns this */
	}

	/*
	 * We always update the parent overlap.  If it's zero we
	 * treat it specially.
	 */
	rbd_dev->parent_overlap = overlap;
	smp_mb();
	if (!overlap) {

		/* A null parent_spec indicates it's the initial probe */

		if (parent_spec) {
			/*
			 * The overlap has become zero, so the clone
			 * must have been resized down to 0 at some
			 * point.  Treat this the same as a flatten.
			 */
			rbd_dev_parent_put(rbd_dev);
			pr_info("%s: clone image now standalone\n",
				rbd_dev->disk->disk_name);
		} else {
			/*
			 * For the initial probe, if we find the
			 * overlap is zero we just pretend there was
			 * no parent image.
			 */
			rbd_warn(rbd_dev, "ignoring parent of "
						"clone with overlap 0\n");
		}
	}
out:
	ret = 0;
out_err:
	kfree(reply_buf);
	rbd_spec_put(parent_spec);

	return ret;
}

static int rbd_dev_v2_striping_info(struct rbd_device *rbd_dev)
{
	struct {
		__le64 stripe_unit;
		__le64 stripe_count;
	} __attribute__ ((packed)) striping_info_buf = { 0 };
	size_t size = sizeof (striping_info_buf);
	void *p;
	u64 obj_size;
	u64 stripe_unit;
	u64 stripe_count;
	int ret;

	ret = rbd_obj_method_sync(rbd_dev, rbd_dev->header_name,
				"rbd", "get_stripe_unit_count", NULL, 0,
				(char *)&striping_info_buf, size);
	dout("%s: rbd_obj_method_sync returned %d\n", __func__, ret);
	if (ret < 0)
		return ret;
	if (ret < size)
		return -ERANGE;

	/*
	 * We don't actually support the "fancy striping" feature
	 * (STRIPINGV2) yet, but if the striping sizes are the
	 * defaults the behavior is the same as before.  So find
	 * out, and only fail if the image has non-default values.
	 */
	ret = -EINVAL;
	obj_size = (u64)1 << rbd_dev->header.obj_order;
	p = &striping_info_buf;
	stripe_unit = ceph_decode_64(&p);
	if (stripe_unit != obj_size) {
		rbd_warn(rbd_dev, "unsupported stripe unit "
				"(got %llu want %llu)",
				stripe_unit, obj_size);
		return -EINVAL;
	}
	stripe_count = ceph_decode_64(&p);
	if (stripe_count != 1) {
		rbd_warn(rbd_dev, "unsupported stripe count "
				"(got %llu want 1)", stripe_count);
		return -EINVAL;
	}
	rbd_dev->header.stripe_unit = stripe_unit;
	rbd_dev->header.stripe_count = stripe_count;

	return 0;
}

static char *rbd_dev_image_name(struct rbd_device *rbd_dev)
{
	size_t image_id_size;
	char *image_id;
	void *p;
	void *end;
	size_t size;
	void *reply_buf = NULL;
	size_t len = 0;
	char *image_name = NULL;
	int ret;

	rbd_assert(!rbd_dev->spec->image_name);

	len = strlen(rbd_dev->spec->image_id);
	image_id_size = sizeof (__le32) + len;
	image_id = kmalloc(image_id_size, GFP_KERNEL);
	if (!image_id)
		return NULL;

	p = image_id;
	end = image_id + image_id_size;
	ceph_encode_string(&p, end, rbd_dev->spec->image_id, (u32)len);

	size = sizeof (__le32) + RBD_IMAGE_NAME_LEN_MAX;
	reply_buf = kmalloc(size, GFP_KERNEL);
	if (!reply_buf)
		goto out;

	ret = rbd_obj_method_sync(rbd_dev, RBD_DIRECTORY,
				"rbd", "dir_get_name",
				image_id, image_id_size,
				reply_buf, size);
	if (ret < 0)
		goto out;
	p = reply_buf;
	end = reply_buf + ret;

	image_name = ceph_extract_encoded_string(&p, end, &len, GFP_KERNEL);
	if (IS_ERR(image_name))
		image_name = NULL;
	else
		dout("%s: name is %s len is %zd\n", __func__, image_name, len);
out:
	kfree(reply_buf);
	kfree(image_id);

	return image_name;
}

static u64 rbd_v1_snap_id_by_name(struct rbd_device *rbd_dev, const char *name)
{
	struct ceph_snap_context *snapc = rbd_dev->header.snapc;
	const char *snap_name;
	u32 which = 0;

	/* Skip over names until we find the one we are looking for */

	snap_name = rbd_dev->header.snap_names;
	while (which < snapc->num_snaps) {
		if (!strcmp(name, snap_name))
			return snapc->snaps[which];
		snap_name += strlen(snap_name) + 1;
		which++;
	}
	return CEPH_NOSNAP;
}

static u64 rbd_v2_snap_id_by_name(struct rbd_device *rbd_dev, const char *name)
{
	struct ceph_snap_context *snapc = rbd_dev->header.snapc;
	u32 which;
	bool found = false;
	u64 snap_id;

	for (which = 0; !found && which < snapc->num_snaps; which++) {
		const char *snap_name;

		snap_id = snapc->snaps[which];
		snap_name = rbd_dev_v2_snap_name(rbd_dev, snap_id);
		if (IS_ERR(snap_name)) {
			/* ignore no-longer existing snapshots */
			if (PTR_ERR(snap_name) == -ENOENT)
				continue;
			else
				break;
		}
		found = !strcmp(name, snap_name);
		kfree(snap_name);
	}
	return found ? snap_id : CEPH_NOSNAP;
}

/*
 * Assumes name is never RBD_SNAP_HEAD_NAME; returns CEPH_NOSNAP if
 * no snapshot by that name is found, or if an error occurs.
 */
static u64 rbd_snap_id_by_name(struct rbd_device *rbd_dev, const char *name)
{
	if (rbd_dev->image_format == 1)
		return rbd_v1_snap_id_by_name(rbd_dev, name);

	return rbd_v2_snap_id_by_name(rbd_dev, name);
}

/*
 * When an rbd image has a parent image, it is identified by the
 * pool, image, and snapshot ids (not names).  This function fills
 * in the names for those ids.  (It's OK if we can't figure out the
 * name for an image id, but the pool and snapshot ids should always
 * exist and have names.)  All names in an rbd spec are dynamically
 * allocated.
 *
 * When an image being mapped (not a parent) is probed, we have the
 * pool name and pool id, image name and image id, and the snapshot
 * name.  The only thing we're missing is the snapshot id.
 */
static int rbd_dev_spec_update(struct rbd_device *rbd_dev)
{
	struct ceph_osd_client *osdc = &rbd_dev->rbd_client->client->osdc;
	struct rbd_spec *spec = rbd_dev->spec;
	const char *pool_name;
	const char *image_name;
	const char *snap_name;
	int ret;

	/*
	 * An image being mapped will have the pool name (etc.), but
	 * we need to look up the snapshot id.
	 */
	if (spec->pool_name) {
		if (strcmp(spec->snap_name, RBD_SNAP_HEAD_NAME)) {
			u64 snap_id;

			snap_id = rbd_snap_id_by_name(rbd_dev, spec->snap_name);
			if (snap_id == CEPH_NOSNAP)
				return -ENOENT;
			spec->snap_id = snap_id;
		} else {
			spec->snap_id = CEPH_NOSNAP;
		}

		return 0;
	}

	/* Get the pool name; we have to make our own copy of this */

	pool_name = ceph_pg_pool_name_by_id(osdc->osdmap, spec->pool_id);
	if (!pool_name) {
		rbd_warn(rbd_dev, "no pool with id %llu", spec->pool_id);
		return -EIO;
	}
	pool_name = kstrdup(pool_name, GFP_KERNEL);
	if (!pool_name)
		return -ENOMEM;

	/* Fetch the image name; tolerate failure here */

	image_name = rbd_dev_image_name(rbd_dev);
	if (!image_name)
		rbd_warn(rbd_dev, "unable to get image name");

	/* Look up the snapshot name, and make a copy */

	snap_name = rbd_snap_name(rbd_dev, spec->snap_id);
	if (IS_ERR(snap_name)) {
		ret = PTR_ERR(snap_name);
		goto out_err;
	}

	spec->pool_name = pool_name;
	spec->image_name = image_name;
	spec->snap_name = snap_name;

	return 0;
out_err:
	kfree(image_name);
	kfree(pool_name);

	return ret;
}

static int rbd_dev_v2_snap_context(struct rbd_device *rbd_dev)
{
	size_t size;
	int ret;
	void *reply_buf;
	void *p;
	void *end;
	u64 seq;
	u32 snap_count;
	struct ceph_snap_context *snapc;
	u32 i;

	/*
	 * We'll need room for the seq value (maximum snapshot id),
	 * snapshot count, and array of that many snapshot ids.
	 * For now we have a fixed upper limit on the number we're
	 * prepared to receive.
	 */
	size = sizeof (__le64) + sizeof (__le32) +
			RBD_MAX_SNAP_COUNT * sizeof (__le64);
	reply_buf = kzalloc(size, GFP_KERNEL);
	if (!reply_buf)
		return -ENOMEM;

	ret = rbd_obj_method_sync(rbd_dev, rbd_dev->header_name,
				"rbd", "get_snapcontext", NULL, 0,
				reply_buf, size);
	dout("%s: rbd_obj_method_sync returned %d\n", __func__, ret);
	if (ret < 0)
		goto out;

	p = reply_buf;
	end = reply_buf + ret;
	ret = -ERANGE;
	ceph_decode_64_safe(&p, end, seq, out);
	ceph_decode_32_safe(&p, end, snap_count, out);

	/*
	 * Make sure the reported number of snapshot ids wouldn't go
	 * beyond the end of our buffer.  But before checking that,
	 * make sure the computed size of the snapshot context we
	 * allocate is representable in a size_t.
	 */
	if (snap_count > (SIZE_MAX - sizeof (struct ceph_snap_context))
				 / sizeof (u64)) {
		ret = -EINVAL;
		goto out;
	}
	if (!ceph_has_room(&p, end, snap_count * sizeof (__le64)))
		goto out;
	ret = 0;

	snapc = ceph_create_snap_context(snap_count, GFP_KERNEL);
	if (!snapc) {
		ret = -ENOMEM;
		goto out;
	}
	snapc->seq = seq;
	for (i = 0; i < snap_count; i++)
		snapc->snaps[i] = ceph_decode_64(&p);

	ceph_put_snap_context(rbd_dev->header.snapc);
	rbd_dev->header.snapc = snapc;

	dout("  snap context seq = %llu, snap_count = %u\n",
		(unsigned long long)seq, (unsigned int)snap_count);
out:
	kfree(reply_buf);

	return ret;
}

static const char *rbd_dev_v2_snap_name(struct rbd_device *rbd_dev,
					u64 snap_id)
{
	size_t size;
	void *reply_buf;
	__le64 snapid;
	int ret;
	void *p;
	void *end;
	char *snap_name;

	size = sizeof (__le32) + RBD_MAX_SNAP_NAME_LEN;
	reply_buf = kmalloc(size, GFP_KERNEL);
	if (!reply_buf)
		return ERR_PTR(-ENOMEM);

	snapid = cpu_to_le64(snap_id);
	ret = rbd_obj_method_sync(rbd_dev, rbd_dev->header_name,
				"rbd", "get_snapshot_name",
				&snapid, sizeof (snapid),
				reply_buf, size);
	dout("%s: rbd_obj_method_sync returned %d\n", __func__, ret);
	if (ret < 0) {
		snap_name = ERR_PTR(ret);
		goto out;
	}

	p = reply_buf;
	end = reply_buf + ret;
	snap_name = ceph_extract_encoded_string(&p, end, NULL, GFP_KERNEL);
	if (IS_ERR(snap_name))
		goto out;

	dout("  snap_id 0x%016llx snap_name = %s\n",
		(unsigned long long)snap_id, snap_name);
out:
	kfree(reply_buf);

	return snap_name;
}

static int rbd_dev_v2_header_info(struct rbd_device *rbd_dev)
{
	bool first_time = rbd_dev->header.object_prefix == NULL;
	int ret;

	ret = rbd_dev_v2_image_size(rbd_dev);
	if (ret)
		return ret;

	if (first_time) {
		ret = rbd_dev_v2_header_onetime(rbd_dev);
		if (ret)
			return ret;
	}

	/*
	 * If the image supports layering, get the parent info.  We
	 * need to probe the first time regardless.  Thereafter we
	 * only need to if there's a parent, to see if it has
	 * disappeared due to the mapped image getting flattened.
	 */
	if (rbd_dev->header.features & RBD_FEATURE_LAYERING &&
			(first_time || rbd_dev->parent_spec)) {
		bool warn;

		ret = rbd_dev_v2_parent_info(rbd_dev);
		if (ret)
			return ret;

		/*
		 * Print a warning if this is the initial probe and
		 * the image has a parent.  Don't print it if the
		 * image now being probed is itself a parent.  We
		 * can tell at this point because we won't know its
		 * pool name yet (just its pool id).
		 */
		warn = rbd_dev->parent_spec && rbd_dev->spec->pool_name;
		if (first_time && warn)
			rbd_warn(rbd_dev, "WARNING: kernel layering "
					"is EXPERIMENTAL!");
	}

	if (rbd_dev->spec->snap_id == CEPH_NOSNAP)
		if (rbd_dev->mapping.size != rbd_dev->header.image_size)
			rbd_dev->mapping.size = rbd_dev->header.image_size;

	ret = rbd_dev_v2_snap_context(rbd_dev);
	dout("rbd_dev_v2_snap_context returned %d\n", ret);

	return ret;
}

static int rbd_bus_add_dev(struct rbd_device *rbd_dev)
{
	struct device *dev;
	int ret;

	dev = &rbd_dev->dev;
	dev->bus = &rbd_bus_type;
	dev->type = &rbd_device_type;
	dev->parent = &rbd_root_dev;
	dev->release = rbd_dev_device_release;
	dev_set_name(dev, "%d", rbd_dev->dev_id);
	ret = device_register(dev);

	return ret;
}

static void rbd_bus_del_dev(struct rbd_device *rbd_dev)
{
	device_unregister(&rbd_dev->dev);
}

static atomic64_t rbd_dev_id_max = ATOMIC64_INIT(0);

/*
 * Get a unique rbd identifier for the given new rbd_dev, and add
 * the rbd_dev to the global list.  The minimum rbd id is 1.
 */
static void rbd_dev_id_get(struct rbd_device *rbd_dev)
{
	rbd_dev->dev_id = atomic64_inc_return(&rbd_dev_id_max);

	spin_lock(&rbd_dev_list_lock);
	list_add_tail(&rbd_dev->node, &rbd_dev_list);
	spin_unlock(&rbd_dev_list_lock);
	dout("rbd_dev %p given dev id %llu\n", rbd_dev,
		(unsigned long long) rbd_dev->dev_id);
}

/*
 * Remove an rbd_dev from the global list, and record that its
 * identifier is no longer in use.
 */
static void rbd_dev_id_put(struct rbd_device *rbd_dev)
{
	struct list_head *tmp;
	int rbd_id = rbd_dev->dev_id;
	int max_id;

	rbd_assert(rbd_id > 0);

	dout("rbd_dev %p released dev id %llu\n", rbd_dev,
		(unsigned long long) rbd_dev->dev_id);
	spin_lock(&rbd_dev_list_lock);
	list_del_init(&rbd_dev->node);

	/*
	 * If the id being "put" is not the current maximum, there
	 * is nothing special we need to do.
	 */
	if (rbd_id != atomic64_read(&rbd_dev_id_max)) {
		spin_unlock(&rbd_dev_list_lock);
		return;
	}

	/*
	 * We need to update the current maximum id.  Search the
	 * list to find out what it is.  We're more likely to find
	 * the maximum at the end, so search the list backward.
	 */
	max_id = 0;
	list_for_each_prev(tmp, &rbd_dev_list) {
		struct rbd_device *rbd_dev;

		rbd_dev = list_entry(tmp, struct rbd_device, node);
		if (rbd_dev->dev_id > max_id)
			max_id = rbd_dev->dev_id;
	}
	spin_unlock(&rbd_dev_list_lock);

	/*
	 * The max id could have been updated by rbd_dev_id_get(), in
	 * which case it now accurately reflects the new maximum.
	 * Be careful not to overwrite the maximum value in that
	 * case.
	 */
	atomic64_cmpxchg(&rbd_dev_id_max, rbd_id, max_id);
	dout("  max dev id has been reset\n");
}

/*
 * Skips over white space at *buf, and updates *buf to point to the
 * first found non-space character (if any). Returns the length of
 * the token (string of non-white space characters) found.  Note
 * that *buf must be terminated with '\0'.
 */
static inline size_t next_token(const char **buf)
{
        /*
        * These are the characters that produce nonzero for
        * isspace() in the "C" and "POSIX" locales.
        */
        const char *spaces = " \f\n\r\t\v";

        *buf += strspn(*buf, spaces);	/* Find start of token */

	return strcspn(*buf, spaces);   /* Return token length */
}

/*
 * Finds the next token in *buf, and if the provided token buffer is
 * big enough, copies the found token into it.  The result, if
 * copied, is guaranteed to be terminated with '\0'.  Note that *buf
 * must be terminated with '\0' on entry.
 *
 * Returns the length of the token found (not including the '\0').
 * Return value will be 0 if no token is found, and it will be >=
 * token_size if the token would not fit.
 *
 * The *buf pointer will be updated to point beyond the end of the
 * found token.  Note that this occurs even if the token buffer is
 * too small to hold it.
 */
static inline size_t copy_token(const char **buf,
				char *token,
				size_t token_size)
{
        size_t len;

	len = next_token(buf);
	if (len < token_size) {
		memcpy(token, *buf, len);
		*(token + len) = '\0';
	}
	*buf += len;

        return len;
}

/*
 * Finds the next token in *buf, dynamically allocates a buffer big
 * enough to hold a copy of it, and copies the token into the new
 * buffer.  The copy is guaranteed to be terminated with '\0'.  Note
 * that a duplicate buffer is created even for a zero-length token.
 *
 * Returns a pointer to the newly-allocated duplicate, or a null
 * pointer if memory for the duplicate was not available.  If
 * the lenp argument is a non-null pointer, the length of the token
 * (not including the '\0') is returned in *lenp.
 *
 * If successful, the *buf pointer will be updated to point beyond
 * the end of the found token.
 *
 * Note: uses GFP_KERNEL for allocation.
 */
static inline char *dup_token(const char **buf, size_t *lenp)
{
	char *dup;
	size_t len;

	len = next_token(buf);
	dup = kmemdup(*buf, len + 1, GFP_KERNEL);
	if (!dup)
		return NULL;
	*(dup + len) = '\0';
	*buf += len;

	if (lenp)
		*lenp = len;

	return dup;
}

/*
 * Parse the options provided for an "rbd add" (i.e., rbd image
 * mapping) request.  These arrive via a write to /sys/bus/rbd/add,
 * and the data written is passed here via a NUL-terminated buffer.
 * Returns 0 if successful or an error code otherwise.
 *
 * The information extracted from these options is recorded in
 * the other parameters which return dynamically-allocated
 * structures:
 *  ceph_opts
 *      The address of a pointer that will refer to a ceph options
 *      structure.  Caller must release the returned pointer using
 *      ceph_destroy_options() when it is no longer needed.
 *  rbd_opts
 *	Address of an rbd options pointer.  Fully initialized by
 *	this function; caller must release with kfree().
 *  spec
 *	Address of an rbd image specification pointer.  Fully
 *	initialized by this function based on parsed options.
 *	Caller must release with rbd_spec_put().
 *
 * The options passed take this form:
 *  <mon_addrs> <options> <pool_name> <image_name> [<snap_id>]
 * where:
 *  <mon_addrs>
 *      A comma-separated list of one or more monitor addresses.
 *      A monitor address is an ip address, optionally followed
 *      by a port number (separated by a colon).
 *        I.e.:  ip1[:port1][,ip2[:port2]...]
 *  <options>
 *      A comma-separated list of ceph and/or rbd options.
 *  <pool_name>
 *      The name of the rados pool containing the rbd image.
 *  <image_name>
 *      The name of the image in that pool to map.
 *  <snap_id>
 *      An optional snapshot id.  If provided, the mapping will
 *      present data from the image at the time that snapshot was
 *      created.  The image head is used if no snapshot id is
 *      provided.  Snapshot mappings are always read-only.
 */
static int rbd_add_parse_args(const char *buf,
				struct ceph_options **ceph_opts,
				struct rbd_options **opts,
				struct rbd_spec **rbd_spec)
{
	size_t len;
	char *options;
	const char *mon_addrs;
	char *snap_name;
	size_t mon_addrs_size;
	struct rbd_spec *spec = NULL;
	struct rbd_options *rbd_opts = NULL;
	struct ceph_options *copts;
	int ret;

	/* The first four tokens are required */

	len = next_token(&buf);
	if (!len) {
		rbd_warn(NULL, "no monitor address(es) provided");
		return -EINVAL;
	}
	mon_addrs = buf;
	mon_addrs_size = len + 1;
	buf += len;

	ret = -EINVAL;
	options = dup_token(&buf, NULL);
	if (!options)
		return -ENOMEM;
	if (!*options) {
		rbd_warn(NULL, "no options provided");
		goto out_err;
	}

	spec = rbd_spec_alloc();
	if (!spec)
		goto out_mem;

	spec->pool_name = dup_token(&buf, NULL);
	if (!spec->pool_name)
		goto out_mem;
	if (!*spec->pool_name) {
		rbd_warn(NULL, "no pool name provided");
		goto out_err;
	}

	spec->image_name = dup_token(&buf, NULL);
	if (!spec->image_name)
		goto out_mem;
	if (!*spec->image_name) {
		rbd_warn(NULL, "no image name provided");
		goto out_err;
	}

	/*
	 * Snapshot name is optional; default is to use "-"
	 * (indicating the head/no snapshot).
	 */
	len = next_token(&buf);
	if (!len) {
		buf = RBD_SNAP_HEAD_NAME; /* No snapshot supplied */
		len = sizeof (RBD_SNAP_HEAD_NAME) - 1;
	} else if (len > RBD_MAX_SNAP_NAME_LEN) {
		ret = -ENAMETOOLONG;
		goto out_err;
	}
	snap_name = kmemdup(buf, len + 1, GFP_KERNEL);
	if (!snap_name)
		goto out_mem;
	*(snap_name + len) = '\0';
	spec->snap_name = snap_name;

	/* Initialize all rbd options to the defaults */

	rbd_opts = kzalloc(sizeof (*rbd_opts), GFP_KERNEL);
	if (!rbd_opts)
		goto out_mem;

	rbd_opts->read_only = RBD_READ_ONLY_DEFAULT;

	copts = ceph_parse_options(options, mon_addrs,
					mon_addrs + mon_addrs_size - 1,
					parse_rbd_opts_token, rbd_opts);
	if (IS_ERR(copts)) {
		ret = PTR_ERR(copts);
		goto out_err;
	}
	kfree(options);

	*ceph_opts = copts;
	*opts = rbd_opts;
	*rbd_spec = spec;

	return 0;
out_mem:
	ret = -ENOMEM;
out_err:
	kfree(rbd_opts);
	rbd_spec_put(spec);
	kfree(options);

	return ret;
}

/*
 * An rbd format 2 image has a unique identifier, distinct from the
 * name given to it by the user.  Internally, that identifier is
 * what's used to specify the names of objects related to the image.
 *
 * A special "rbd id" object is used to map an rbd image name to its
 * id.  If that object doesn't exist, then there is no v2 rbd image
 * with the supplied name.
 *
 * This function will record the given rbd_dev's image_id field if
 * it can be determined, and in that case will return 0.  If any
 * errors occur a negative errno will be returned and the rbd_dev's
 * image_id field will be unchanged (and should be NULL).
 */
static int rbd_dev_image_id(struct rbd_device *rbd_dev)
{
	int ret;
	size_t size;
	char *object_name;
	void *response;
	char *image_id;

	/*
	 * When probing a parent image, the image id is already
	 * known (and the image name likely is not).  There's no
	 * need to fetch the image id again in this case.  We
	 * do still need to set the image format though.
	 */
	if (rbd_dev->spec->image_id) {
		rbd_dev->image_format = *rbd_dev->spec->image_id ? 2 : 1;

		return 0;
	}

	/*
	 * First, see if the format 2 image id file exists, and if
	 * so, get the image's persistent id from it.
	 */
	size = sizeof (RBD_ID_PREFIX) + strlen(rbd_dev->spec->image_name);
	object_name = kmalloc(size, GFP_NOIO);
	if (!object_name)
		return -ENOMEM;
	sprintf(object_name, "%s%s", RBD_ID_PREFIX, rbd_dev->spec->image_name);
	dout("rbd id object name is %s\n", object_name);

	/* Response will be an encoded string, which includes a length */

	size = sizeof (__le32) + RBD_IMAGE_ID_LEN_MAX;
	response = kzalloc(size, GFP_NOIO);
	if (!response) {
		ret = -ENOMEM;
		goto out;
	}

	/* If it doesn't exist we'll assume it's a format 1 image */

	ret = rbd_obj_method_sync(rbd_dev, object_name,
				"rbd", "get_id", NULL, 0,
				response, RBD_IMAGE_ID_LEN_MAX);
	dout("%s: rbd_obj_method_sync returned %d\n", __func__, ret);
	if (ret == -ENOENT) {
		image_id = kstrdup("", GFP_KERNEL);
		ret = image_id ? 0 : -ENOMEM;
		if (!ret)
			rbd_dev->image_format = 1;
	} else if (ret > sizeof (__le32)) {
		void *p = response;

		image_id = ceph_extract_encoded_string(&p, p + ret,
						NULL, GFP_NOIO);
		ret = IS_ERR(image_id) ? PTR_ERR(image_id) : 0;
		if (!ret)
			rbd_dev->image_format = 2;
	} else {
		ret = -EINVAL;
	}

	if (!ret) {
		rbd_dev->spec->image_id = image_id;
		dout("image_id is %s\n", image_id);
	}
out:
	kfree(response);
	kfree(object_name);

	return ret;
}

/*
 * Undo whatever state changes are made by v1 or v2 header info
 * call.
 */
static void rbd_dev_unprobe(struct rbd_device *rbd_dev)
{
	struct rbd_image_header	*header;

	/* Drop parent reference unless it's already been done (or none) */

	if (rbd_dev->parent_overlap)
		rbd_dev_parent_put(rbd_dev);

	/* Free dynamic fields from the header, then zero it out */

	header = &rbd_dev->header;
	ceph_put_snap_context(header->snapc);
	kfree(header->snap_sizes);
	kfree(header->snap_names);
	kfree(header->object_prefix);
	memset(header, 0, sizeof (*header));
}

static int rbd_dev_v2_header_onetime(struct rbd_device *rbd_dev)
{
	int ret;

	ret = rbd_dev_v2_object_prefix(rbd_dev);
	if (ret)
		goto out_err;

	/*
	 * Get the and check features for the image.  Currently the
	 * features are assumed to never change.
	 */
	ret = rbd_dev_v2_features(rbd_dev);
	if (ret)
		goto out_err;

	/* If the image supports fancy striping, get its parameters */

	if (rbd_dev->header.features & RBD_FEATURE_STRIPINGV2) {
		ret = rbd_dev_v2_striping_info(rbd_dev);
		if (ret < 0)
			goto out_err;
	}
	/* No support for crypto and compression type format 2 images */

	return 0;
out_err:
	rbd_dev->header.features = 0;
	kfree(rbd_dev->header.object_prefix);
	rbd_dev->header.object_prefix = NULL;

	return ret;
}

static int rbd_dev_probe_parent(struct rbd_device *rbd_dev)
{
	struct rbd_device *parent = NULL;
	struct rbd_spec *parent_spec;
	struct rbd_client *rbdc;
	int ret;

	if (!rbd_dev->parent_spec)
		return 0;
	/*
	 * We need to pass a reference to the client and the parent
	 * spec when creating the parent rbd_dev.  Images related by
	 * parent/child relationships always share both.
	 */
	parent_spec = rbd_spec_get(rbd_dev->parent_spec);
	rbdc = __rbd_get_client(rbd_dev->rbd_client);

	ret = -ENOMEM;
	parent = rbd_dev_create(rbdc, parent_spec);
	if (!parent)
		goto out_err;

	ret = rbd_dev_image_probe(parent, false);
	if (ret < 0)
		goto out_err;
	rbd_dev->parent = parent;
	atomic_set(&rbd_dev->parent_ref, 1);

	return 0;
out_err:
	if (parent) {
		rbd_dev_unparent(rbd_dev);
		kfree(rbd_dev->header_name);
		rbd_dev_destroy(parent);
	} else {
		rbd_put_client(rbdc);
		rbd_spec_put(parent_spec);
	}

	return ret;
}

static int rbd_dev_device_setup(struct rbd_device *rbd_dev)
{
	int ret;

	/* generate unique id: find highest unique id, add one */
	rbd_dev_id_get(rbd_dev);

	/* Fill in the device name, now that we have its id. */
	BUILD_BUG_ON(DEV_NAME_LEN
			< sizeof (RBD_DRV_NAME) + MAX_INT_FORMAT_WIDTH);
	sprintf(rbd_dev->name, "%s%d", RBD_DRV_NAME, rbd_dev->dev_id);

	/* Get our block major device number. */

	ret = register_blkdev(0, rbd_dev->name);
	if (ret < 0)
		goto err_out_id;
	rbd_dev->major = ret;

	/* Set up the blkdev mapping. */

	ret = rbd_init_disk(rbd_dev);
	if (ret)
		goto err_out_blkdev;

	ret = rbd_dev_mapping_set(rbd_dev);
	if (ret)
		goto err_out_disk;
	set_capacity(rbd_dev->disk, rbd_dev->mapping.size / SECTOR_SIZE);

	ret = rbd_bus_add_dev(rbd_dev);
	if (ret)
		goto err_out_mapping;

	/* Everything's ready.  Announce the disk to the world. */

	set_bit(RBD_DEV_FLAG_EXISTS, &rbd_dev->flags);
	add_disk(rbd_dev->disk);

	pr_info("%s: added with size 0x%llx\n", rbd_dev->disk->disk_name,
		(unsigned long long) rbd_dev->mapping.size);

	return ret;

err_out_mapping:
	rbd_dev_mapping_clear(rbd_dev);
err_out_disk:
	rbd_free_disk(rbd_dev);
err_out_blkdev:
	unregister_blkdev(rbd_dev->major, rbd_dev->name);
err_out_id:
	rbd_dev_id_put(rbd_dev);
	rbd_dev_mapping_clear(rbd_dev);

	return ret;
}

static int rbd_dev_header_name(struct rbd_device *rbd_dev)
{
	struct rbd_spec *spec = rbd_dev->spec;
	size_t size;

	/* Record the header object name for this rbd image. */

	rbd_assert(rbd_image_format_valid(rbd_dev->image_format));

	if (rbd_dev->image_format == 1)
		size = strlen(spec->image_name) + sizeof (RBD_SUFFIX);
	else
		size = sizeof (RBD_HEADER_PREFIX) + strlen(spec->image_id);

	rbd_dev->header_name = kmalloc(size, GFP_KERNEL);
	if (!rbd_dev->header_name)
		return -ENOMEM;

	if (rbd_dev->image_format == 1)
		sprintf(rbd_dev->header_name, "%s%s",
			spec->image_name, RBD_SUFFIX);
	else
		sprintf(rbd_dev->header_name, "%s%s",
			RBD_HEADER_PREFIX, spec->image_id);
	return 0;
}

static void rbd_dev_image_release(struct rbd_device *rbd_dev)
{
	rbd_dev_unprobe(rbd_dev);
	kfree(rbd_dev->header_name);
	rbd_dev->header_name = NULL;
	rbd_dev->image_format = 0;
	kfree(rbd_dev->spec->image_id);
	rbd_dev->spec->image_id = NULL;

	rbd_dev_destroy(rbd_dev);
}

/*
 * Probe for the existence of the header object for the given rbd
 * device.  If this image is the one being mapped (i.e., not a
 * parent), initiate a watch on its header object before using that
 * object to get detailed information about the rbd image.
 */
static int rbd_dev_image_probe(struct rbd_device *rbd_dev, bool mapping)
{
	int ret;
	int tmp;

	/*
	 * Get the id from the image id object.  Unless there's an
	 * error, rbd_dev->spec->image_id will be filled in with
	 * a dynamically-allocated string, and rbd_dev->image_format
	 * will be set to either 1 or 2.
	 */
	ret = rbd_dev_image_id(rbd_dev);
	if (ret)
		return ret;
	rbd_assert(rbd_dev->spec->image_id);
	rbd_assert(rbd_image_format_valid(rbd_dev->image_format));

	ret = rbd_dev_header_name(rbd_dev);
	if (ret)
		goto err_out_format;

	if (mapping) {
		ret = rbd_dev_header_watch_sync(rbd_dev, true);
		if (ret)
			goto out_header_name;
	}

	if (rbd_dev->image_format == 1)
		ret = rbd_dev_v1_header_info(rbd_dev);
	else
		ret = rbd_dev_v2_header_info(rbd_dev);
	if (ret)
		goto err_out_watch;

	ret = rbd_dev_spec_update(rbd_dev);
	if (ret)
		goto err_out_probe;

	ret = rbd_dev_probe_parent(rbd_dev);
	if (ret)
		goto err_out_probe;

	dout("discovered format %u image, header name is %s\n",
		rbd_dev->image_format, rbd_dev->header_name);

	return 0;
err_out_probe:
	rbd_dev_unprobe(rbd_dev);
err_out_watch:
	if (mapping) {
		tmp = rbd_dev_header_watch_sync(rbd_dev, false);
		if (tmp)
			rbd_warn(rbd_dev, "unable to tear down "
					"watch request (%d)\n", tmp);
	}
out_header_name:
	kfree(rbd_dev->header_name);
	rbd_dev->header_name = NULL;
err_out_format:
	rbd_dev->image_format = 0;
	kfree(rbd_dev->spec->image_id);
	rbd_dev->spec->image_id = NULL;

	dout("probe failed, returning %d\n", ret);

	return ret;
}

static ssize_t rbd_add(struct bus_type *bus,
		       const char *buf,
		       size_t count)
{
	struct rbd_device *rbd_dev = NULL;
	struct ceph_options *ceph_opts = NULL;
	struct rbd_options *rbd_opts = NULL;
	struct rbd_spec *spec = NULL;
	struct rbd_client *rbdc;
	struct ceph_osd_client *osdc;
	bool read_only;
	int rc = -ENOMEM;

	if (!try_module_get(THIS_MODULE))
		return -ENODEV;

	/* parse add command */
	rc = rbd_add_parse_args(buf, &ceph_opts, &rbd_opts, &spec);
	if (rc < 0)
		goto err_out_module;
	read_only = rbd_opts->read_only;
	kfree(rbd_opts);
	rbd_opts = NULL;	/* done with this */

	rbdc = rbd_get_client(ceph_opts);
	if (IS_ERR(rbdc)) {
		rc = PTR_ERR(rbdc);
		goto err_out_args;
	}

	/* pick the pool */
	osdc = &rbdc->client->osdc;
	rc = ceph_pg_poolid_by_name(osdc->osdmap, spec->pool_name);
	if (rc < 0)
		goto err_out_client;
	spec->pool_id = (u64)rc;

	/* The ceph file layout needs to fit pool id in 32 bits */

	if (spec->pool_id > (u64)U32_MAX) {
		rbd_warn(NULL, "pool id too large (%llu > %u)\n",
				(unsigned long long)spec->pool_id, U32_MAX);
		rc = -EIO;
		goto err_out_client;
	}

	rbd_dev = rbd_dev_create(rbdc, spec);
	if (!rbd_dev)
		goto err_out_client;
	rbdc = NULL;		/* rbd_dev now owns this */
	spec = NULL;		/* rbd_dev now owns this */

	rc = rbd_dev_image_probe(rbd_dev, true);
	if (rc < 0)
		goto err_out_rbd_dev;

	/* If we are mapping a snapshot it must be marked read-only */

	if (rbd_dev->spec->snap_id != CEPH_NOSNAP)
		read_only = true;
	rbd_dev->mapping.read_only = read_only;

	rc = rbd_dev_device_setup(rbd_dev);
	if (rc) {
		rbd_dev_image_release(rbd_dev);
		goto err_out_module;
	}

	return count;

err_out_rbd_dev:
	rbd_dev_destroy(rbd_dev);
err_out_client:
	rbd_put_client(rbdc);
err_out_args:
	rbd_spec_put(spec);
err_out_module:
	module_put(THIS_MODULE);

	dout("Error adding device %s\n", buf);

	return (ssize_t)rc;
}

static void rbd_dev_device_release(struct device *dev)
{
	struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);

	rbd_free_disk(rbd_dev);
	clear_bit(RBD_DEV_FLAG_EXISTS, &rbd_dev->flags);
	rbd_dev_mapping_clear(rbd_dev);
	unregister_blkdev(rbd_dev->major, rbd_dev->name);
	rbd_dev->major = 0;
	rbd_dev_id_put(rbd_dev);
	rbd_dev_mapping_clear(rbd_dev);
}

static void rbd_dev_remove_parent(struct rbd_device *rbd_dev)
{
	while (rbd_dev->parent) {
		struct rbd_device *first = rbd_dev;
		struct rbd_device *second = first->parent;
		struct rbd_device *third;

		/*
		 * Follow to the parent with no grandparent and
		 * remove it.
		 */
		while (second && (third = second->parent)) {
			first = second;
			second = third;
		}
		rbd_assert(second);
		rbd_dev_image_release(second);
		first->parent = NULL;
		first->parent_overlap = 0;

		rbd_assert(first->parent_spec);
		rbd_spec_put(first->parent_spec);
		first->parent_spec = NULL;
	}
}

static ssize_t rbd_remove(struct bus_type *bus,
			  const char *buf,
			  size_t count)
{
	struct rbd_device *rbd_dev = NULL;
	struct list_head *tmp;
	int dev_id;
	unsigned long ul;
	bool already = false;
	int ret;

	ret = kstrtoul(buf, 10, &ul);
	if (ret)
		return ret;

	/* convert to int; abort if we lost anything in the conversion */
	dev_id = (int)ul;
	if (dev_id != ul)
		return -EINVAL;

	ret = -ENOENT;
	spin_lock(&rbd_dev_list_lock);
	list_for_each(tmp, &rbd_dev_list) {
		rbd_dev = list_entry(tmp, struct rbd_device, node);
		if (rbd_dev->dev_id == dev_id) {
			ret = 0;
			break;
		}
	}
	if (!ret) {
		spin_lock_irq(&rbd_dev->lock);
		if (rbd_dev->open_count)
			ret = -EBUSY;
		else
			already = test_and_set_bit(RBD_DEV_FLAG_REMOVING,
							&rbd_dev->flags);
		spin_unlock_irq(&rbd_dev->lock);
	}
	spin_unlock(&rbd_dev_list_lock);
	if (ret < 0 || already)
		return ret;

	ret = rbd_dev_header_watch_sync(rbd_dev, false);
	if (ret)
		rbd_warn(rbd_dev, "failed to cancel watch event (%d)\n", ret);

	/*
	 * flush remaining watch callbacks - these must be complete
	 * before the osd_client is shutdown
	 */
	dout("%s: flushing notifies", __func__);
	ceph_osdc_flush_notifies(&rbd_dev->rbd_client->client->osdc);
	/*
	 * Don't free anything from rbd_dev->disk until after all
	 * notifies are completely processed. Otherwise
	 * rbd_bus_del_dev() will race with rbd_watch_cb(), resulting
	 * in a potential use after free of rbd_dev->disk or rbd_dev.
	 */
	rbd_bus_del_dev(rbd_dev);
	rbd_dev_image_release(rbd_dev);
	module_put(THIS_MODULE);

	return count;
}

/*
 * create control files in sysfs
 * /sys/bus/rbd/...
 */
static int rbd_sysfs_init(void)
{
	int ret;

	ret = device_register(&rbd_root_dev);
	if (ret < 0)
		return ret;

	ret = bus_register(&rbd_bus_type);
	if (ret < 0)
		device_unregister(&rbd_root_dev);

	return ret;
}

static void rbd_sysfs_cleanup(void)
{
	bus_unregister(&rbd_bus_type);
	device_unregister(&rbd_root_dev);
}

static int rbd_slab_init(void)
{
	rbd_assert(!rbd_img_request_cache);
	rbd_img_request_cache = kmem_cache_create("rbd_img_request",
					sizeof (struct rbd_img_request),
					__alignof__(struct rbd_img_request),
					0, NULL);
	if (!rbd_img_request_cache)
		return -ENOMEM;

	rbd_assert(!rbd_obj_request_cache);
	rbd_obj_request_cache = kmem_cache_create("rbd_obj_request",
					sizeof (struct rbd_obj_request),
					__alignof__(struct rbd_obj_request),
					0, NULL);
	if (!rbd_obj_request_cache)
		goto out_err;

	rbd_assert(!rbd_segment_name_cache);
	rbd_segment_name_cache = kmem_cache_create("rbd_segment_name",
					MAX_OBJ_NAME_SIZE + 1, 1, 0, NULL);
	if (rbd_segment_name_cache)
		return 0;
out_err:
	if (rbd_obj_request_cache) {
		kmem_cache_destroy(rbd_obj_request_cache);
		rbd_obj_request_cache = NULL;
	}

	kmem_cache_destroy(rbd_img_request_cache);
	rbd_img_request_cache = NULL;

	return -ENOMEM;
}

static void rbd_slab_exit(void)
{
	rbd_assert(rbd_segment_name_cache);
	kmem_cache_destroy(rbd_segment_name_cache);
	rbd_segment_name_cache = NULL;

	rbd_assert(rbd_obj_request_cache);
	kmem_cache_destroy(rbd_obj_request_cache);
	rbd_obj_request_cache = NULL;

	rbd_assert(rbd_img_request_cache);
	kmem_cache_destroy(rbd_img_request_cache);
	rbd_img_request_cache = NULL;
}

static int __init rbd_init(void)
{
	int rc;

	if (!libceph_compatible(NULL)) {
		rbd_warn(NULL, "libceph incompatibility (quitting)");

		return -EINVAL;
	}
	rc = rbd_slab_init();
	if (rc)
		return rc;
	rc = rbd_sysfs_init();
	if (rc)
		rbd_slab_exit();
	else
		pr_info("loaded " RBD_DRV_NAME_LONG "\n");

	return rc;
}

static void __exit rbd_exit(void)
{
	rbd_sysfs_cleanup();
	rbd_slab_exit();
}

module_init(rbd_init);
module_exit(rbd_exit);

MODULE_AUTHOR("Alex Elder <elder@inktank.com>");
MODULE_AUTHOR("Sage Weil <sage@newdream.net>");
MODULE_AUTHOR("Yehuda Sadeh <yehuda@hq.newdream.net>");
MODULE_DESCRIPTION("rados block device");

/* following authorship retained from original osdblk.c */
MODULE_AUTHOR("Jeff Garzik <jeff@garzik.org>");

MODULE_LICENSE("GPL");