Eric Lee / smarc-fsl-linux-kernel

xfs_log.c 106 KB
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 
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
 * All Rights Reserved.
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_errortag.h"
#include "xfs_error.h"
#include "xfs_trans.h"
#include "xfs_trans_priv.h"
#include "xfs_log.h"
#include "xfs_log_priv.h"
#include "xfs_trace.h"
#include "xfs_sysfs.h"
#include "xfs_sb.h"
#include "xfs_health.h"

kmem_zone_t	*xfs_log_ticket_zone;

/* Local miscellaneous function prototypes */
STATIC struct xlog *
xlog_alloc_log(
	struct xfs_mount	*mp,
	struct xfs_buftarg	*log_target,
	xfs_daddr_t		blk_offset,
	int			num_bblks);
STATIC int
xlog_space_left(
	struct xlog		*log,
	atomic64_t		*head);
STATIC void
xlog_dealloc_log(
	struct xlog		*log);

/* local state machine functions */
STATIC void xlog_state_done_syncing(
	struct xlog_in_core	*iclog);
STATIC int
xlog_state_get_iclog_space(
	struct xlog		*log,
	int			len,
	struct xlog_in_core	**iclog,
	struct xlog_ticket	*ticket,
	int			*continued_write,
	int			*logoffsetp);
STATIC void
xlog_state_switch_iclogs(
	struct xlog		*log,
	struct xlog_in_core	*iclog,
	int			eventual_size);
STATIC void
xlog_grant_push_ail(
	struct xlog		*log,
	int			need_bytes);
STATIC void
xlog_sync(
	struct xlog		*log,
	struct xlog_in_core	*iclog);
#if defined(DEBUG)
STATIC void
xlog_verify_dest_ptr(
	struct xlog		*log,
	void			*ptr);
STATIC void
xlog_verify_grant_tail(
	struct xlog *log);
STATIC void
xlog_verify_iclog(
	struct xlog		*log,
	struct xlog_in_core	*iclog,
	int			count);
STATIC void
xlog_verify_tail_lsn(
	struct xlog		*log,
	struct xlog_in_core	*iclog,
	xfs_lsn_t		tail_lsn);
#else
#define xlog_verify_dest_ptr(a,b)
#define xlog_verify_grant_tail(a)
#define xlog_verify_iclog(a,b,c)
#define xlog_verify_tail_lsn(a,b,c)
#endif

STATIC int
xlog_iclogs_empty(
	struct xlog		*log);

static void
xlog_grant_sub_space(
	struct xlog		*log,
	atomic64_t		*head,
	int			bytes)
{
	int64_t	head_val = atomic64_read(head);
	int64_t new, old;

	do {
		int	cycle, space;

		xlog_crack_grant_head_val(head_val, &cycle, &space);

		space -= bytes;
		if (space < 0) {
			space += log->l_logsize;
			cycle--;
		}

		old = head_val;
		new = xlog_assign_grant_head_val(cycle, space);
		head_val = atomic64_cmpxchg(head, old, new);
	} while (head_val != old);
}

static void
xlog_grant_add_space(
	struct xlog		*log,
	atomic64_t		*head,
	int			bytes)
{
	int64_t	head_val = atomic64_read(head);
	int64_t new, old;

	do {
		int		tmp;
		int		cycle, space;

		xlog_crack_grant_head_val(head_val, &cycle, &space);

		tmp = log->l_logsize - space;
		if (tmp > bytes)
			space += bytes;
		else {
			space = bytes - tmp;
			cycle++;
		}

		old = head_val;
		new = xlog_assign_grant_head_val(cycle, space);
		head_val = atomic64_cmpxchg(head, old, new);
	} while (head_val != old);
}

STATIC void
xlog_grant_head_init(
	struct xlog_grant_head	*head)
{
	xlog_assign_grant_head(&head->grant, 1, 0);
	INIT_LIST_HEAD(&head->waiters);
	spin_lock_init(&head->lock);
}

STATIC void
xlog_grant_head_wake_all(
	struct xlog_grant_head	*head)
{
	struct xlog_ticket	*tic;

	spin_lock(&head->lock);
	list_for_each_entry(tic, &head->waiters, t_queue)
		wake_up_process(tic->t_task);
	spin_unlock(&head->lock);
}

static inline int
xlog_ticket_reservation(
	struct xlog		*log,
	struct xlog_grant_head	*head,
	struct xlog_ticket	*tic)
{
	if (head == &log->l_write_head) {
		ASSERT(tic->t_flags & XLOG_TIC_PERM_RESERV);
		return tic->t_unit_res;
	} else {
		if (tic->t_flags & XLOG_TIC_PERM_RESERV)
			return tic->t_unit_res * tic->t_cnt;
		else
			return tic->t_unit_res;
	}
}

STATIC bool
xlog_grant_head_wake(
	struct xlog		*log,
	struct xlog_grant_head	*head,
	int			*free_bytes)
{
	struct xlog_ticket	*tic;
	int			need_bytes;
	bool			woken_task = false;

	list_for_each_entry(tic, &head->waiters, t_queue) {

		/*
		 * There is a chance that the size of the CIL checkpoints in
		 * progress at the last AIL push target calculation resulted in
		 * limiting the target to the log head (l_last_sync_lsn) at the
		 * time. This may not reflect where the log head is now as the
		 * CIL checkpoints may have completed.
		 *
		 * Hence when we are woken here, it may be that the head of the
		 * log that has moved rather than the tail. As the tail didn't
		 * move, there still won't be space available for the
		 * reservation we require.  However, if the AIL has already
		 * pushed to the target defined by the old log head location, we
		 * will hang here waiting for something else to update the AIL
		 * push target.
		 *
		 * Therefore, if there isn't space to wake the first waiter on
		 * the grant head, we need to push the AIL again to ensure the
		 * target reflects both the current log tail and log head
		 * position before we wait for the tail to move again.
		 */

		need_bytes = xlog_ticket_reservation(log, head, tic);
		if (*free_bytes < need_bytes) {
			if (!woken_task)
				xlog_grant_push_ail(log, need_bytes);
			return false;
		}

		*free_bytes -= need_bytes;
		trace_xfs_log_grant_wake_up(log, tic);
		wake_up_process(tic->t_task);
		woken_task = true;
	}

	return true;
}

STATIC int
xlog_grant_head_wait(
	struct xlog		*log,
	struct xlog_grant_head	*head,
	struct xlog_ticket	*tic,
	int			need_bytes) __releases(&head->lock)
					    __acquires(&head->lock)
{
	list_add_tail(&tic->t_queue, &head->waiters);

	do {
		if (XLOG_FORCED_SHUTDOWN(log))
			goto shutdown;
		xlog_grant_push_ail(log, need_bytes);

		__set_current_state(TASK_UNINTERRUPTIBLE);
		spin_unlock(&head->lock);

		XFS_STATS_INC(log->l_mp, xs_sleep_logspace);

		trace_xfs_log_grant_sleep(log, tic);
		schedule();
		trace_xfs_log_grant_wake(log, tic);

		spin_lock(&head->lock);
		if (XLOG_FORCED_SHUTDOWN(log))
			goto shutdown;
	} while (xlog_space_left(log, &head->grant) < need_bytes);

	list_del_init(&tic->t_queue);
	return 0;
shutdown:
	list_del_init(&tic->t_queue);
	return -EIO;
}

/*
 * Atomically get the log space required for a log ticket.
 *
 * Once a ticket gets put onto head->waiters, it will only return after the
 * needed reservation is satisfied.
 *
 * This function is structured so that it has a lock free fast path. This is
 * necessary because every new transaction reservation will come through this
 * path. Hence any lock will be globally hot if we take it unconditionally on
 * every pass.
 *
 * As tickets are only ever moved on and off head->waiters under head->lock, we
 * only need to take that lock if we are going to add the ticket to the queue
 * and sleep. We can avoid taking the lock if the ticket was never added to
 * head->waiters because the t_queue list head will be empty and we hold the
 * only reference to it so it can safely be checked unlocked.
 */
STATIC int
xlog_grant_head_check(
	struct xlog		*log,
	struct xlog_grant_head	*head,
	struct xlog_ticket	*tic,
	int			*need_bytes)
{
	int			free_bytes;
	int			error = 0;

	ASSERT(!(log->l_flags & XLOG_ACTIVE_RECOVERY));

	/*
	 * If there are other waiters on the queue then give them a chance at
	 * logspace before us.  Wake up the first waiters, if we do not wake
	 * up all the waiters then go to sleep waiting for more free space,
	 * otherwise try to get some space for this transaction.
	 */
	*need_bytes = xlog_ticket_reservation(log, head, tic);
	free_bytes = xlog_space_left(log, &head->grant);
	if (!list_empty_careful(&head->waiters)) {
		spin_lock(&head->lock);
		if (!xlog_grant_head_wake(log, head, &free_bytes) ||
		    free_bytes < *need_bytes) {
			error = xlog_grant_head_wait(log, head, tic,
						     *need_bytes);
		}
		spin_unlock(&head->lock);
	} else if (free_bytes < *need_bytes) {
		spin_lock(&head->lock);
		error = xlog_grant_head_wait(log, head, tic, *need_bytes);
		spin_unlock(&head->lock);
	}

	return error;
}

static void
xlog_tic_reset_res(xlog_ticket_t *tic)
{
	tic->t_res_num = 0;
	tic->t_res_arr_sum = 0;
	tic->t_res_num_ophdrs = 0;
}

static void
xlog_tic_add_region(xlog_ticket_t *tic, uint len, uint type)
{
	if (tic->t_res_num == XLOG_TIC_LEN_MAX) {
		/* add to overflow and start again */
		tic->t_res_o_flow += tic->t_res_arr_sum;
		tic->t_res_num = 0;
		tic->t_res_arr_sum = 0;
	}

	tic->t_res_arr[tic->t_res_num].r_len = len;
	tic->t_res_arr[tic->t_res_num].r_type = type;
	tic->t_res_arr_sum += len;
	tic->t_res_num++;
}

/*
 * Replenish the byte reservation required by moving the grant write head.
 */
int
xfs_log_regrant(
	struct xfs_mount	*mp,
	struct xlog_ticket	*tic)
{
	struct xlog		*log = mp->m_log;
	int			need_bytes;
	int			error = 0;

	if (XLOG_FORCED_SHUTDOWN(log))
		return -EIO;

	XFS_STATS_INC(mp, xs_try_logspace);

	/*
	 * This is a new transaction on the ticket, so we need to change the
	 * transaction ID so that the next transaction has a different TID in
	 * the log. Just add one to the existing tid so that we can see chains
	 * of rolling transactions in the log easily.
	 */
	tic->t_tid++;

	xlog_grant_push_ail(log, tic->t_unit_res);

	tic->t_curr_res = tic->t_unit_res;
	xlog_tic_reset_res(tic);

	if (tic->t_cnt > 0)
		return 0;

	trace_xfs_log_regrant(log, tic);

	error = xlog_grant_head_check(log, &log->l_write_head, tic,
				      &need_bytes);
	if (error)
		goto out_error;

	xlog_grant_add_space(log, &log->l_write_head.grant, need_bytes);
	trace_xfs_log_regrant_exit(log, tic);
	xlog_verify_grant_tail(log);
	return 0;

out_error:
	/*
	 * If we are failing, make sure the ticket doesn't have any current
	 * reservations.  We don't want to add this back when the ticket/
	 * transaction gets cancelled.
	 */
	tic->t_curr_res = 0;
	tic->t_cnt = 0;	/* ungrant will give back unit_res * t_cnt. */
	return error;
}

/*
 * Reserve log space and return a ticket corresponding to the reservation.
 *
 * Each reservation is going to reserve extra space for a log record header.
 * When writes happen to the on-disk log, we don't subtract the length of the
 * log record header from any reservation.  By wasting space in each
 * reservation, we prevent over allocation problems.
 */
int
xfs_log_reserve(
	struct xfs_mount	*mp,
	int		 	unit_bytes,
	int		 	cnt,
	struct xlog_ticket	**ticp,
	uint8_t		 	client,
	bool			permanent)
{
	struct xlog		*log = mp->m_log;
	struct xlog_ticket	*tic;
	int			need_bytes;
	int			error = 0;

	ASSERT(client == XFS_TRANSACTION || client == XFS_LOG);

	if (XLOG_FORCED_SHUTDOWN(log))
		return -EIO;

	XFS_STATS_INC(mp, xs_try_logspace);

	ASSERT(*ticp == NULL);
	tic = xlog_ticket_alloc(log, unit_bytes, cnt, client, permanent);
	*ticp = tic;

	xlog_grant_push_ail(log, tic->t_cnt ? tic->t_unit_res * tic->t_cnt
					    : tic->t_unit_res);

	trace_xfs_log_reserve(log, tic);

	error = xlog_grant_head_check(log, &log->l_reserve_head, tic,
				      &need_bytes);
	if (error)
		goto out_error;

	xlog_grant_add_space(log, &log->l_reserve_head.grant, need_bytes);
	xlog_grant_add_space(log, &log->l_write_head.grant, need_bytes);
	trace_xfs_log_reserve_exit(log, tic);
	xlog_verify_grant_tail(log);
	return 0;

out_error:
	/*
	 * If we are failing, make sure the ticket doesn't have any current
	 * reservations.  We don't want to add this back when the ticket/
	 * transaction gets cancelled.
	 */
	tic->t_curr_res = 0;
	tic->t_cnt = 0;	/* ungrant will give back unit_res * t_cnt. */
	return error;
}

static bool
__xlog_state_release_iclog(
	struct xlog		*log,
	struct xlog_in_core	*iclog)
{
	lockdep_assert_held(&log->l_icloglock);

	if (iclog->ic_state == XLOG_STATE_WANT_SYNC) {
		/* update tail before writing to iclog */
		xfs_lsn_t tail_lsn = xlog_assign_tail_lsn(log->l_mp);

		iclog->ic_state = XLOG_STATE_SYNCING;
		iclog->ic_header.h_tail_lsn = cpu_to_be64(tail_lsn);
		xlog_verify_tail_lsn(log, iclog, tail_lsn);
		/* cycle incremented when incrementing curr_block */
		return true;
	}

	ASSERT(iclog->ic_state == XLOG_STATE_ACTIVE);
	return false;
}

/*
 * Flush iclog to disk if this is the last reference to the given iclog and the
 * it is in the WANT_SYNC state.
 */
static int
xlog_state_release_iclog(
	struct xlog		*log,
	struct xlog_in_core	*iclog)
{
	lockdep_assert_held(&log->l_icloglock);

	if (iclog->ic_state == XLOG_STATE_IOERROR)
		return -EIO;

	if (atomic_dec_and_test(&iclog->ic_refcnt) &&
	    __xlog_state_release_iclog(log, iclog)) {
		spin_unlock(&log->l_icloglock);
		xlog_sync(log, iclog);
		spin_lock(&log->l_icloglock);
	}

	return 0;
}

void
xfs_log_release_iclog(
	struct xlog_in_core	*iclog)
{
	struct xlog		*log = iclog->ic_log;
	bool			sync = false;

	if (atomic_dec_and_lock(&iclog->ic_refcnt, &log->l_icloglock)) {
		if (iclog->ic_state != XLOG_STATE_IOERROR)
			sync = __xlog_state_release_iclog(log, iclog);
		spin_unlock(&log->l_icloglock);
	}

	if (sync)
		xlog_sync(log, iclog);
}

/*
 * Mount a log filesystem
 *
 * mp		- ubiquitous xfs mount point structure
 * log_target	- buftarg of on-disk log device
 * blk_offset	- Start block # where block size is 512 bytes (BBSIZE)
 * num_bblocks	- Number of BBSIZE blocks in on-disk log
 *
 * Return error or zero.
 */
int
xfs_log_mount(
	xfs_mount_t	*mp,
	xfs_buftarg_t	*log_target,
	xfs_daddr_t	blk_offset,
	int		num_bblks)
{
	bool		fatal = xfs_sb_version_hascrc(&mp->m_sb);
	int		error = 0;
	int		min_logfsbs;

	if (!(mp->m_flags & XFS_MOUNT_NORECOVERY)) {
		xfs_notice(mp, "Mounting V%d Filesystem",
			   XFS_SB_VERSION_NUM(&mp->m_sb));
	} else {
		xfs_notice(mp,
"Mounting V%d filesystem in no-recovery mode. Filesystem will be inconsistent.",
			   XFS_SB_VERSION_NUM(&mp->m_sb));
		ASSERT(mp->m_flags & XFS_MOUNT_RDONLY);
	}

	mp->m_log = xlog_alloc_log(mp, log_target, blk_offset, num_bblks);
	if (IS_ERR(mp->m_log)) {
		error = PTR_ERR(mp->m_log);
		goto out;
	}

	/*
	 * Validate the given log space and drop a critical message via syslog
	 * if the log size is too small that would lead to some unexpected
	 * situations in transaction log space reservation stage.
	 *
	 * Note: we can't just reject the mount if the validation fails.  This
	 * would mean that people would have to downgrade their kernel just to
	 * remedy the situation as there is no way to grow the log (short of
	 * black magic surgery with xfs_db).
	 *
	 * We can, however, reject mounts for CRC format filesystems, as the
	 * mkfs binary being used to make the filesystem should never create a
	 * filesystem with a log that is too small.
	 */
	min_logfsbs = xfs_log_calc_minimum_size(mp);

	if (mp->m_sb.sb_logblocks < min_logfsbs) {
		xfs_warn(mp,
		"Log size %d blocks too small, minimum size is %d blocks",
			 mp->m_sb.sb_logblocks, min_logfsbs);
		error = -EINVAL;
	} else if (mp->m_sb.sb_logblocks > XFS_MAX_LOG_BLOCKS) {
		xfs_warn(mp,
		"Log size %d blocks too large, maximum size is %lld blocks",
			 mp->m_sb.sb_logblocks, XFS_MAX_LOG_BLOCKS);
		error = -EINVAL;
	} else if (XFS_FSB_TO_B(mp, mp->m_sb.sb_logblocks) > XFS_MAX_LOG_BYTES) {
		xfs_warn(mp,
		"log size %lld bytes too large, maximum size is %lld bytes",
			 XFS_FSB_TO_B(mp, mp->m_sb.sb_logblocks),
			 XFS_MAX_LOG_BYTES);
		error = -EINVAL;
	} else if (mp->m_sb.sb_logsunit > 1 &&
		   mp->m_sb.sb_logsunit % mp->m_sb.sb_blocksize) {
		xfs_warn(mp,
		"log stripe unit %u bytes must be a multiple of block size",
			 mp->m_sb.sb_logsunit);
		error = -EINVAL;
		fatal = true;
	}
	if (error) {
		/*
		 * Log check errors are always fatal on v5; or whenever bad
		 * metadata leads to a crash.
		 */
		if (fatal) {
			xfs_crit(mp, "AAIEEE! Log failed size checks. Abort!");
			ASSERT(0);
			goto out_free_log;
		}
		xfs_crit(mp, "Log size out of supported range.");
		xfs_crit(mp,
"Continuing onwards, but if log hangs are experienced then please report this message in the bug report.");
	}

	/*
	 * Initialize the AIL now we have a log.
	 */
	error = xfs_trans_ail_init(mp);
	if (error) {
		xfs_warn(mp, "AIL initialisation failed: error %d", error);
		goto out_free_log;
	}
	mp->m_log->l_ailp = mp->m_ail;

	/*
	 * skip log recovery on a norecovery mount.  pretend it all
	 * just worked.
	 */
	if (!(mp->m_flags & XFS_MOUNT_NORECOVERY)) {
		int	readonly = (mp->m_flags & XFS_MOUNT_RDONLY);

		if (readonly)
			mp->m_flags &= ~XFS_MOUNT_RDONLY;

		error = xlog_recover(mp->m_log);

		if (readonly)
			mp->m_flags |= XFS_MOUNT_RDONLY;
		if (error) {
			xfs_warn(mp, "log mount/recovery failed: error %d",
				error);
			xlog_recover_cancel(mp->m_log);
			goto out_destroy_ail;
		}
	}

	error = xfs_sysfs_init(&mp->m_log->l_kobj, &xfs_log_ktype, &mp->m_kobj,
			       "log");
	if (error)
		goto out_destroy_ail;

	/* Normal transactions can now occur */
	mp->m_log->l_flags &= ~XLOG_ACTIVE_RECOVERY;

	/*
	 * Now the log has been fully initialised and we know were our
	 * space grant counters are, we can initialise the permanent ticket
	 * needed for delayed logging to work.
	 */
	xlog_cil_init_post_recovery(mp->m_log);

	return 0;

out_destroy_ail:
	xfs_trans_ail_destroy(mp);
out_free_log:
	xlog_dealloc_log(mp->m_log);
out:
	return error;
}

/*
 * Finish the recovery of the file system.  This is separate from the
 * xfs_log_mount() call, because it depends on the code in xfs_mountfs() to read
 * in the root and real-time bitmap inodes between calling xfs_log_mount() and
 * here.
 *
 * If we finish recovery successfully, start the background log work. If we are
 * not doing recovery, then we have a RO filesystem and we don't need to start
 * it.
 */
int
xfs_log_mount_finish(
	struct xfs_mount	*mp)
{
	int	error = 0;
	bool	readonly = (mp->m_flags & XFS_MOUNT_RDONLY);
	bool	recovered = mp->m_log->l_flags & XLOG_RECOVERY_NEEDED;

	if (mp->m_flags & XFS_MOUNT_NORECOVERY) {
		ASSERT(mp->m_flags & XFS_MOUNT_RDONLY);
		return 0;
	} else if (readonly) {
		/* Allow unlinked processing to proceed */
		mp->m_flags &= ~XFS_MOUNT_RDONLY;
	}

	/*
	 * During the second phase of log recovery, we need iget and
	 * iput to behave like they do for an active filesystem.
	 * xfs_fs_drop_inode needs to be able to prevent the deletion
	 * of inodes before we're done replaying log items on those
	 * inodes.  Turn it off immediately after recovery finishes
	 * so that we don't leak the quota inodes if subsequent mount
	 * activities fail.
	 *
	 * We let all inodes involved in redo item processing end up on
	 * the LRU instead of being evicted immediately so that if we do
	 * something to an unlinked inode, the irele won't cause
	 * premature truncation and freeing of the inode, which results
	 * in log recovery failure.  We have to evict the unreferenced
	 * lru inodes after clearing SB_ACTIVE because we don't
	 * otherwise clean up the lru if there's a subsequent failure in
	 * xfs_mountfs, which leads to us leaking the inodes if nothing
	 * else (e.g. quotacheck) references the inodes before the
	 * mount failure occurs.
	 */
	mp->m_super->s_flags |= SB_ACTIVE;
	error = xlog_recover_finish(mp->m_log);
	if (!error)
		xfs_log_work_queue(mp);
	mp->m_super->s_flags &= ~SB_ACTIVE;
	evict_inodes(mp->m_super);

	/*
	 * Drain the buffer LRU after log recovery. This is required for v4
	 * filesystems to avoid leaving around buffers with NULL verifier ops,
	 * but we do it unconditionally to make sure we're always in a clean
	 * cache state after mount.
	 *
	 * Don't push in the error case because the AIL may have pending intents
	 * that aren't removed until recovery is cancelled.
	 */
	if (!error && recovered) {
		xfs_log_force(mp, XFS_LOG_SYNC);
		xfs_ail_push_all_sync(mp->m_ail);
	}
	xfs_wait_buftarg(mp->m_ddev_targp);

	if (readonly)
		mp->m_flags |= XFS_MOUNT_RDONLY;

	return error;
}

/*
 * The mount has failed. Cancel the recovery if it hasn't completed and destroy
 * the log.
 */
void
xfs_log_mount_cancel(
	struct xfs_mount	*mp)
{
	xlog_recover_cancel(mp->m_log);
	xfs_log_unmount(mp);
}

/*
 * Wait for the iclog to be written disk, or return an error if the log has been
 * shut down.
 */
static int
xlog_wait_on_iclog(
	struct xlog_in_core	*iclog)
		__releases(iclog->ic_log->l_icloglock)
{
	struct xlog		*log = iclog->ic_log;

	if (!XLOG_FORCED_SHUTDOWN(log) &&
	    iclog->ic_state != XLOG_STATE_ACTIVE &&
	    iclog->ic_state != XLOG_STATE_DIRTY) {
		XFS_STATS_INC(log->l_mp, xs_log_force_sleep);
		xlog_wait(&iclog->ic_force_wait, &log->l_icloglock);
	} else {
		spin_unlock(&log->l_icloglock);
	}

	if (XLOG_FORCED_SHUTDOWN(log))
		return -EIO;
	return 0;
}

/*
 * Write out an unmount record using the ticket provided. We have to account for
 * the data space used in the unmount ticket as this write is not done from a
 * transaction context that has already done the accounting for us.
 */
static int
xlog_write_unmount_record(
	struct xlog		*log,
	struct xlog_ticket	*ticket,
	xfs_lsn_t		*lsn,
	uint			flags)
{
	struct xfs_unmount_log_format ulf = {
		.magic = XLOG_UNMOUNT_TYPE,
	};
	struct xfs_log_iovec reg = {
		.i_addr = &ulf,
		.i_len = sizeof(ulf),
		.i_type = XLOG_REG_TYPE_UNMOUNT,
	};
	struct xfs_log_vec vec = {
		.lv_niovecs = 1,
		.lv_iovecp = &reg,
	};

	/* account for space used by record data */
	ticket->t_curr_res -= sizeof(ulf);
	return xlog_write(log, &vec, ticket, lsn, NULL, flags, false);
}

/*
 * Mark the filesystem clean by writing an unmount record to the head of the
 * log.
 */
static void
xlog_unmount_write(
	struct xlog		*log)
{
	struct xfs_mount	*mp = log->l_mp;
	struct xlog_in_core	*iclog;
	struct xlog_ticket	*tic = NULL;
	xfs_lsn_t		lsn;
	uint			flags = XLOG_UNMOUNT_TRANS;
	int			error;

	error = xfs_log_reserve(mp, 600, 1, &tic, XFS_LOG, 0);
	if (error)
		goto out_err;

	error = xlog_write_unmount_record(log, tic, &lsn, flags);
	/*
	 * At this point, we're umounting anyway, so there's no point in
	 * transitioning log state to IOERROR. Just continue...
	 */
out_err:
	if (error)
		xfs_alert(mp, "%s: unmount record failed", __func__);

	spin_lock(&log->l_icloglock);
	iclog = log->l_iclog;
	atomic_inc(&iclog->ic_refcnt);
	if (iclog->ic_state == XLOG_STATE_ACTIVE)
		xlog_state_switch_iclogs(log, iclog, 0);
	else
		ASSERT(iclog->ic_state == XLOG_STATE_WANT_SYNC ||
		       iclog->ic_state == XLOG_STATE_IOERROR);
	error = xlog_state_release_iclog(log, iclog);
	xlog_wait_on_iclog(iclog);

	if (tic) {
		trace_xfs_log_umount_write(log, tic);
		xfs_log_ticket_ungrant(log, tic);
	}
}

static void
xfs_log_unmount_verify_iclog(
	struct xlog		*log)
{
	struct xlog_in_core	*iclog = log->l_iclog;

	do {
		ASSERT(iclog->ic_state == XLOG_STATE_ACTIVE);
		ASSERT(iclog->ic_offset == 0);
	} while ((iclog = iclog->ic_next) != log->l_iclog);
}

/*
 * Unmount record used to have a string "Unmount filesystem--" in the
 * data section where the "Un" was really a magic number (XLOG_UNMOUNT_TYPE).
 * We just write the magic number now since that particular field isn't
 * currently architecture converted and "Unmount" is a bit foo.
 * As far as I know, there weren't any dependencies on the old behaviour.
 */
static void
xfs_log_unmount_write(
	struct xfs_mount	*mp)
{
	struct xlog		*log = mp->m_log;

	/*
	 * Don't write out unmount record on norecovery mounts or ro devices.
	 * Or, if we are doing a forced umount (typically because of IO errors).
	 */
	if (mp->m_flags & XFS_MOUNT_NORECOVERY ||
	    xfs_readonly_buftarg(log->l_targ)) {
		ASSERT(mp->m_flags & XFS_MOUNT_RDONLY);
		return;
	}

	xfs_log_force(mp, XFS_LOG_SYNC);

	if (XLOG_FORCED_SHUTDOWN(log))
		return;

	/*
	 * If we think the summary counters are bad, avoid writing the unmount
	 * record to force log recovery at next mount, after which the summary
	 * counters will be recalculated.  Refer to xlog_check_unmount_rec for
	 * more details.
	 */
	if (XFS_TEST_ERROR(xfs_fs_has_sickness(mp, XFS_SICK_FS_COUNTERS), mp,
			XFS_ERRTAG_FORCE_SUMMARY_RECALC)) {
		xfs_alert(mp, "%s: will fix summary counters at next mount",
				__func__);
		return;
	}

	xfs_log_unmount_verify_iclog(log);
	xlog_unmount_write(log);
}

/*
 * Empty the log for unmount/freeze.
 *
 * To do this, we first need to shut down the background log work so it is not
 * trying to cover the log as we clean up. We then need to unpin all objects in
 * the log so we can then flush them out. Once they have completed their IO and
 * run the callbacks removing themselves from the AIL, we can write the unmount
 * record.
 */
void
xfs_log_quiesce(
	struct xfs_mount	*mp)
{
	cancel_delayed_work_sync(&mp->m_log->l_work);
	xfs_log_force(mp, XFS_LOG_SYNC);

	/*
	 * The superblock buffer is uncached and while xfs_ail_push_all_sync()
	 * will push it, xfs_wait_buftarg() will not wait for it. Further,
	 * xfs_buf_iowait() cannot be used because it was pushed with the
	 * XBF_ASYNC flag set, so we need to use a lock/unlock pair to wait for
	 * the IO to complete.
	 */
	xfs_ail_push_all_sync(mp->m_ail);
	xfs_wait_buftarg(mp->m_ddev_targp);
	xfs_buf_lock(mp->m_sb_bp);
	xfs_buf_unlock(mp->m_sb_bp);

	xfs_log_unmount_write(mp);
}

/*
 * Shut down and release the AIL and Log.
 *
 * During unmount, we need to ensure we flush all the dirty metadata objects
 * from the AIL so that the log is empty before we write the unmount record to
 * the log. Once this is done, we can tear down the AIL and the log.
 */
void
xfs_log_unmount(
	struct xfs_mount	*mp)
{
	xfs_log_quiesce(mp);

	xfs_trans_ail_destroy(mp);

	xfs_sysfs_del(&mp->m_log->l_kobj);

	xlog_dealloc_log(mp->m_log);
}

void
xfs_log_item_init(
	struct xfs_mount	*mp,
	struct xfs_log_item	*item,
	int			type,
	const struct xfs_item_ops *ops)
{
	item->li_mountp = mp;
	item->li_ailp = mp->m_ail;
	item->li_type = type;
	item->li_ops = ops;
	item->li_lv = NULL;

	INIT_LIST_HEAD(&item->li_ail);
	INIT_LIST_HEAD(&item->li_cil);
	INIT_LIST_HEAD(&item->li_bio_list);
	INIT_LIST_HEAD(&item->li_trans);
}

/*
 * Wake up processes waiting for log space after we have moved the log tail.
 */
void
xfs_log_space_wake(
	struct xfs_mount	*mp)
{
	struct xlog		*log = mp->m_log;
	int			free_bytes;

	if (XLOG_FORCED_SHUTDOWN(log))
		return;

	if (!list_empty_careful(&log->l_write_head.waiters)) {
		ASSERT(!(log->l_flags & XLOG_ACTIVE_RECOVERY));

		spin_lock(&log->l_write_head.lock);
		free_bytes = xlog_space_left(log, &log->l_write_head.grant);
		xlog_grant_head_wake(log, &log->l_write_head, &free_bytes);
		spin_unlock(&log->l_write_head.lock);
	}

	if (!list_empty_careful(&log->l_reserve_head.waiters)) {
		ASSERT(!(log->l_flags & XLOG_ACTIVE_RECOVERY));

		spin_lock(&log->l_reserve_head.lock);
		free_bytes = xlog_space_left(log, &log->l_reserve_head.grant);
		xlog_grant_head_wake(log, &log->l_reserve_head, &free_bytes);
		spin_unlock(&log->l_reserve_head.lock);
	}
}

/*
 * Determine if we have a transaction that has gone to disk that needs to be
 * covered. To begin the transition to the idle state firstly the log needs to
 * be idle. That means the CIL, the AIL and the iclogs needs to be empty before
 * we start attempting to cover the log.
 *
 * Only if we are then in a state where covering is needed, the caller is
 * informed that dummy transactions are required to move the log into the idle
 * state.
 *
 * If there are any items in the AIl or CIL, then we do not want to attempt to
 * cover the log as we may be in a situation where there isn't log space
 * available to run a dummy transaction and this can lead to deadlocks when the
 * tail of the log is pinned by an item that is modified in the CIL.  Hence
 * there's no point in running a dummy transaction at this point because we
 * can't start trying to idle the log until both the CIL and AIL are empty.
 */
static int
xfs_log_need_covered(xfs_mount_t *mp)
{
	struct xlog	*log = mp->m_log;
	int		needed = 0;

	if (!xfs_fs_writable(mp, SB_FREEZE_WRITE))
		return 0;

	if (!xlog_cil_empty(log))
		return 0;

	spin_lock(&log->l_icloglock);
	switch (log->l_covered_state) {
	case XLOG_STATE_COVER_DONE:
	case XLOG_STATE_COVER_DONE2:
	case XLOG_STATE_COVER_IDLE:
		break;
	case XLOG_STATE_COVER_NEED:
	case XLOG_STATE_COVER_NEED2:
		if (xfs_ail_min_lsn(log->l_ailp))
			break;
		if (!xlog_iclogs_empty(log))
			break;

		needed = 1;
		if (log->l_covered_state == XLOG_STATE_COVER_NEED)
			log->l_covered_state = XLOG_STATE_COVER_DONE;
		else
			log->l_covered_state = XLOG_STATE_COVER_DONE2;
		break;
	default:
		needed = 1;
		break;
	}
	spin_unlock(&log->l_icloglock);
	return needed;
}

/*
 * We may be holding the log iclog lock upon entering this routine.
 */
xfs_lsn_t
xlog_assign_tail_lsn_locked(
	struct xfs_mount	*mp)
{
	struct xlog		*log = mp->m_log;
	struct xfs_log_item	*lip;
	xfs_lsn_t		tail_lsn;

	assert_spin_locked(&mp->m_ail->ail_lock);

	/*
	 * To make sure we always have a valid LSN for the log tail we keep
	 * track of the last LSN which was committed in log->l_last_sync_lsn,
	 * and use that when the AIL was empty.
	 */
	lip = xfs_ail_min(mp->m_ail);
	if (lip)
		tail_lsn = lip->li_lsn;
	else
		tail_lsn = atomic64_read(&log->l_last_sync_lsn);
	trace_xfs_log_assign_tail_lsn(log, tail_lsn);
	atomic64_set(&log->l_tail_lsn, tail_lsn);
	return tail_lsn;
}

xfs_lsn_t
xlog_assign_tail_lsn(
	struct xfs_mount	*mp)
{
	xfs_lsn_t		tail_lsn;

	spin_lock(&mp->m_ail->ail_lock);
	tail_lsn = xlog_assign_tail_lsn_locked(mp);
	spin_unlock(&mp->m_ail->ail_lock);

	return tail_lsn;
}

/*
 * Return the space in the log between the tail and the head.  The head
 * is passed in the cycle/bytes formal parms.  In the special case where
 * the reserve head has wrapped passed the tail, this calculation is no
 * longer valid.  In this case, just return 0 which means there is no space
 * in the log.  This works for all places where this function is called
 * with the reserve head.  Of course, if the write head were to ever
 * wrap the tail, we should blow up.  Rather than catch this case here,
 * we depend on other ASSERTions in other parts of the code.   XXXmiken
 *
 * This code also handles the case where the reservation head is behind
 * the tail.  The details of this case are described below, but the end
 * result is that we return the size of the log as the amount of space left.
 */
STATIC int
xlog_space_left(
	struct xlog	*log,
	atomic64_t	*head)
{
	int		free_bytes;
	int		tail_bytes;
	int		tail_cycle;
	int		head_cycle;
	int		head_bytes;

	xlog_crack_grant_head(head, &head_cycle, &head_bytes);
	xlog_crack_atomic_lsn(&log->l_tail_lsn, &tail_cycle, &tail_bytes);
	tail_bytes = BBTOB(tail_bytes);
	if (tail_cycle == head_cycle && head_bytes >= tail_bytes)
		free_bytes = log->l_logsize - (head_bytes - tail_bytes);
	else if (tail_cycle + 1 < head_cycle)
		return 0;
	else if (tail_cycle < head_cycle) {
		ASSERT(tail_cycle == (head_cycle - 1));
		free_bytes = tail_bytes - head_bytes;
	} else {
		/*
		 * The reservation head is behind the tail.
		 * In this case we just want to return the size of the
		 * log as the amount of space left.
		 */
		xfs_alert(log->l_mp, "xlog_space_left: head behind tail");
		xfs_alert(log->l_mp,
			  "  tail_cycle = %d, tail_bytes = %d",
			  tail_cycle, tail_bytes);
		xfs_alert(log->l_mp,
			  "  GH   cycle = %d, GH   bytes = %d",
			  head_cycle, head_bytes);
		ASSERT(0);
		free_bytes = log->l_logsize;
	}
	return free_bytes;
}


static void
xlog_ioend_work(
	struct work_struct	*work)
{
	struct xlog_in_core     *iclog =
		container_of(work, struct xlog_in_core, ic_end_io_work);
	struct xlog		*log = iclog->ic_log;
	int			error;

	error = blk_status_to_errno(iclog->ic_bio.bi_status);
#ifdef DEBUG
	/* treat writes with injected CRC errors as failed */
	if (iclog->ic_fail_crc)
		error = -EIO;
#endif

	/*
	 * Race to shutdown the filesystem if we see an error.
	 */
	if (XFS_TEST_ERROR(error, log->l_mp, XFS_ERRTAG_IODONE_IOERR)) {
		xfs_alert(log->l_mp, "log I/O error %d", error);
		xfs_force_shutdown(log->l_mp, SHUTDOWN_LOG_IO_ERROR);
	}

	xlog_state_done_syncing(iclog);
	bio_uninit(&iclog->ic_bio);

	/*
	 * Drop the lock to signal that we are done. Nothing references the
	 * iclog after this, so an unmount waiting on this lock can now tear it
	 * down safely. As such, it is unsafe to reference the iclog after the
	 * unlock as we could race with it being freed.
	 */
	up(&iclog->ic_sema);
}

/*
 * Return size of each in-core log record buffer.
 *
 * All machines get 8 x 32kB buffers by default, unless tuned otherwise.
 *
 * If the filesystem blocksize is too large, we may need to choose a
 * larger size since the directory code currently logs entire blocks.
 */
STATIC void
xlog_get_iclog_buffer_size(
	struct xfs_mount	*mp,
	struct xlog		*log)
{
	if (mp->m_logbufs <= 0)
		mp->m_logbufs = XLOG_MAX_ICLOGS;
	if (mp->m_logbsize <= 0)
		mp->m_logbsize = XLOG_BIG_RECORD_BSIZE;

	log->l_iclog_bufs = mp->m_logbufs;
	log->l_iclog_size = mp->m_logbsize;

	/*
	 * # headers = size / 32k - one header holds cycles from 32k of data.
	 */
	log->l_iclog_heads =
		DIV_ROUND_UP(mp->m_logbsize, XLOG_HEADER_CYCLE_SIZE);
	log->l_iclog_hsize = log->l_iclog_heads << BBSHIFT;
}

void
xfs_log_work_queue(
	struct xfs_mount        *mp)
{
	queue_delayed_work(mp->m_sync_workqueue, &mp->m_log->l_work,
				msecs_to_jiffies(xfs_syncd_centisecs * 10));
}

/*
 * Every sync period we need to unpin all items in the AIL and push them to
 * disk. If there is nothing dirty, then we might need to cover the log to
 * indicate that the filesystem is idle.
 */
static void
xfs_log_worker(
	struct work_struct	*work)
{
	struct xlog		*log = container_of(to_delayed_work(work),
						struct xlog, l_work);
	struct xfs_mount	*mp = log->l_mp;

	/* dgc: errors ignored - not fatal and nowhere to report them */
	if (xfs_log_need_covered(mp)) {
		/*
		 * Dump a transaction into the log that contains no real change.
		 * This is needed to stamp the current tail LSN into the log
		 * during the covering operation.
		 *
		 * We cannot use an inode here for this - that will push dirty
		 * state back up into the VFS and then periodic inode flushing
		 * will prevent log covering from making progress. Hence we
		 * synchronously log the superblock instead to ensure the
		 * superblock is immediately unpinned and can be written back.
		 */
		xfs_sync_sb(mp, true);
	} else
		xfs_log_force(mp, 0);

	/* start pushing all the metadata that is currently dirty */
	xfs_ail_push_all(mp->m_ail);

	/* queue us up again */
	xfs_log_work_queue(mp);
}

/*
 * This routine initializes some of the log structure for a given mount point.
 * Its primary purpose is to fill in enough, so recovery can occur.  However,
 * some other stuff may be filled in too.
 */
STATIC struct xlog *
xlog_alloc_log(
	struct xfs_mount	*mp,
	struct xfs_buftarg	*log_target,
	xfs_daddr_t		blk_offset,
	int			num_bblks)
{
	struct xlog		*log;
	xlog_rec_header_t	*head;
	xlog_in_core_t		**iclogp;
	xlog_in_core_t		*iclog, *prev_iclog=NULL;
	int			i;
	int			error = -ENOMEM;
	uint			log2_size = 0;

	log = kmem_zalloc(sizeof(struct xlog), KM_MAYFAIL);
	if (!log) {
		xfs_warn(mp, "Log allocation failed: No memory!");
		goto out;
	}

	log->l_mp	   = mp;
	log->l_targ	   = log_target;
	log->l_logsize     = BBTOB(num_bblks);
	log->l_logBBstart  = blk_offset;
	log->l_logBBsize   = num_bblks;
	log->l_covered_state = XLOG_STATE_COVER_IDLE;
	log->l_flags	   |= XLOG_ACTIVE_RECOVERY;
	INIT_DELAYED_WORK(&log->l_work, xfs_log_worker);

	log->l_prev_block  = -1;
	/* log->l_tail_lsn = 0x100000000LL; cycle = 1; current block = 0 */
	xlog_assign_atomic_lsn(&log->l_tail_lsn, 1, 0);
	xlog_assign_atomic_lsn(&log->l_last_sync_lsn, 1, 0);
	log->l_curr_cycle  = 1;	    /* 0 is bad since this is initial value */

	xlog_grant_head_init(&log->l_reserve_head);
	xlog_grant_head_init(&log->l_write_head);

	error = -EFSCORRUPTED;
	if (xfs_sb_version_hassector(&mp->m_sb)) {
	        log2_size = mp->m_sb.sb_logsectlog;
		if (log2_size < BBSHIFT) {
			xfs_warn(mp, "Log sector size too small (0x%x < 0x%x)",
				log2_size, BBSHIFT);
			goto out_free_log;
		}

	        log2_size -= BBSHIFT;
		if (log2_size > mp->m_sectbb_log) {
			xfs_warn(mp, "Log sector size too large (0x%x > 0x%x)",
				log2_size, mp->m_sectbb_log);
			goto out_free_log;
		}

		/* for larger sector sizes, must have v2 or external log */
		if (log2_size && log->l_logBBstart > 0 &&
			    !xfs_sb_version_haslogv2(&mp->m_sb)) {
			xfs_warn(mp,
		"log sector size (0x%x) invalid for configuration.",
				log2_size);
			goto out_free_log;
		}
	}
	log->l_sectBBsize = 1 << log2_size;

	xlog_get_iclog_buffer_size(mp, log);

	spin_lock_init(&log->l_icloglock);
	init_waitqueue_head(&log->l_flush_wait);

	iclogp = &log->l_iclog;
	/*
	 * The amount of memory to allocate for the iclog structure is
	 * rather funky due to the way the structure is defined.  It is
	 * done this way so that we can use different sizes for machines
	 * with different amounts of memory.  See the definition of
	 * xlog_in_core_t in xfs_log_priv.h for details.
	 */
	ASSERT(log->l_iclog_size >= 4096);
	for (i = 0; i < log->l_iclog_bufs; i++) {
		int align_mask = xfs_buftarg_dma_alignment(mp->m_logdev_targp);
		size_t bvec_size = howmany(log->l_iclog_size, PAGE_SIZE) *
				sizeof(struct bio_vec);

		iclog = kmem_zalloc(sizeof(*iclog) + bvec_size, KM_MAYFAIL);
		if (!iclog)
			goto out_free_iclog;

		*iclogp = iclog;
		iclog->ic_prev = prev_iclog;
		prev_iclog = iclog;

		iclog->ic_data = kmem_alloc_io(log->l_iclog_size, align_mask,
						KM_MAYFAIL | KM_ZERO);
		if (!iclog->ic_data)
			goto out_free_iclog;
#ifdef DEBUG
		log->l_iclog_bak[i] = &iclog->ic_header;
#endif
		head = &iclog->ic_header;
		memset(head, 0, sizeof(xlog_rec_header_t));
		head->h_magicno = cpu_to_be32(XLOG_HEADER_MAGIC_NUM);
		head->h_version = cpu_to_be32(
			xfs_sb_version_haslogv2(&log->l_mp->m_sb) ? 2 : 1);
		head->h_size = cpu_to_be32(log->l_iclog_size);
		/* new fields */
		head->h_fmt = cpu_to_be32(XLOG_FMT);
		memcpy(&head->h_fs_uuid, &mp->m_sb.sb_uuid, sizeof(uuid_t));

		iclog->ic_size = log->l_iclog_size - log->l_iclog_hsize;
		iclog->ic_state = XLOG_STATE_ACTIVE;
		iclog->ic_log = log;
		atomic_set(&iclog->ic_refcnt, 0);
		spin_lock_init(&iclog->ic_callback_lock);
		INIT_LIST_HEAD(&iclog->ic_callbacks);
		iclog->ic_datap = (char *)iclog->ic_data + log->l_iclog_hsize;

		init_waitqueue_head(&iclog->ic_force_wait);
		init_waitqueue_head(&iclog->ic_write_wait);
		INIT_WORK(&iclog->ic_end_io_work, xlog_ioend_work);
		sema_init(&iclog->ic_sema, 1);

		iclogp = &iclog->ic_next;
	}
	*iclogp = log->l_iclog;			/* complete ring */
	log->l_iclog->ic_prev = prev_iclog;	/* re-write 1st prev ptr */

	log->l_ioend_workqueue = alloc_workqueue("xfs-log/%s",
			WQ_MEM_RECLAIM | WQ_FREEZABLE | WQ_HIGHPRI, 0,
			mp->m_super->s_id);
	if (!log->l_ioend_workqueue)
		goto out_free_iclog;

	error = xlog_cil_init(log);
	if (error)
		goto out_destroy_workqueue;
	return log;

out_destroy_workqueue:
	destroy_workqueue(log->l_ioend_workqueue);
out_free_iclog:
	for (iclog = log->l_iclog; iclog; iclog = prev_iclog) {
		prev_iclog = iclog->ic_next;
		kmem_free(iclog->ic_data);
		kmem_free(iclog);
		if (prev_iclog == log->l_iclog)
			break;
	}
out_free_log:
	kmem_free(log);
out:
	return ERR_PTR(error);
}	/* xlog_alloc_log */

/*
 * Write out the commit record of a transaction associated with the given
 * ticket to close off a running log write. Return the lsn of the commit record.
 */
int
xlog_commit_record(
	struct xlog		*log,
	struct xlog_ticket	*ticket,
	struct xlog_in_core	**iclog,
	xfs_lsn_t		*lsn)
{
	struct xfs_log_iovec reg = {
		.i_addr = NULL,
		.i_len = 0,
		.i_type = XLOG_REG_TYPE_COMMIT,
	};
	struct xfs_log_vec vec = {
		.lv_niovecs = 1,
		.lv_iovecp = &reg,
	};
	int	error;

	if (XLOG_FORCED_SHUTDOWN(log))
		return -EIO;

	error = xlog_write(log, &vec, ticket, lsn, iclog, XLOG_COMMIT_TRANS,
			   false);
	if (error)
		xfs_force_shutdown(log->l_mp, SHUTDOWN_LOG_IO_ERROR);
	return error;
}

/*
 * Compute the LSN that we'd need to push the log tail towards in order to have
 * (a) enough on-disk log space to log the number of bytes specified, (b) at
 * least 25% of the log space free, and (c) at least 256 blocks free.  If the
 * log free space already meets all three thresholds, this function returns
 * NULLCOMMITLSN.
 */
xfs_lsn_t
xlog_grant_push_threshold(
	struct xlog	*log,
	int		need_bytes)
{
	xfs_lsn_t	threshold_lsn = 0;
	xfs_lsn_t	last_sync_lsn;
	int		free_blocks;
	int		free_bytes;
	int		threshold_block;
	int		threshold_cycle;
	int		free_threshold;

	ASSERT(BTOBB(need_bytes) < log->l_logBBsize);

	free_bytes = xlog_space_left(log, &log->l_reserve_head.grant);
	free_blocks = BTOBBT(free_bytes);

	/*
	 * Set the threshold for the minimum number of free blocks in the
	 * log to the maximum of what the caller needs, one quarter of the
	 * log, and 256 blocks.
	 */
	free_threshold = BTOBB(need_bytes);
	free_threshold = max(free_threshold, (log->l_logBBsize >> 2));
	free_threshold = max(free_threshold, 256);
	if (free_blocks >= free_threshold)
		return NULLCOMMITLSN;

	xlog_crack_atomic_lsn(&log->l_tail_lsn, &threshold_cycle,
						&threshold_block);
	threshold_block += free_threshold;
	if (threshold_block >= log->l_logBBsize) {
		threshold_block -= log->l_logBBsize;
		threshold_cycle += 1;
	}
	threshold_lsn = xlog_assign_lsn(threshold_cycle,
					threshold_block);
	/*
	 * Don't pass in an lsn greater than the lsn of the last
	 * log record known to be on disk. Use a snapshot of the last sync lsn
	 * so that it doesn't change between the compare and the set.
	 */
	last_sync_lsn = atomic64_read(&log->l_last_sync_lsn);
	if (XFS_LSN_CMP(threshold_lsn, last_sync_lsn) > 0)
		threshold_lsn = last_sync_lsn;

	return threshold_lsn;
}

/*
 * Push the tail of the log if we need to do so to maintain the free log space
 * thresholds set out by xlog_grant_push_threshold.  We may need to adopt a
 * policy which pushes on an lsn which is further along in the log once we
 * reach the high water mark.  In this manner, we would be creating a low water
 * mark.
 */
STATIC void
xlog_grant_push_ail(
	struct xlog	*log,
	int		need_bytes)
{
	xfs_lsn_t	threshold_lsn;

	threshold_lsn = xlog_grant_push_threshold(log, need_bytes);
	if (threshold_lsn == NULLCOMMITLSN || XLOG_FORCED_SHUTDOWN(log))
		return;

	/*
	 * Get the transaction layer to kick the dirty buffers out to
	 * disk asynchronously. No point in trying to do this if
	 * the filesystem is shutting down.
	 */
	xfs_ail_push(log->l_ailp, threshold_lsn);
}

/*
 * Stamp cycle number in every block
 */
STATIC void
xlog_pack_data(
	struct xlog		*log,
	struct xlog_in_core	*iclog,
	int			roundoff)
{
	int			i, j, k;
	int			size = iclog->ic_offset + roundoff;
	__be32			cycle_lsn;
	char			*dp;

	cycle_lsn = CYCLE_LSN_DISK(iclog->ic_header.h_lsn);

	dp = iclog->ic_datap;
	for (i = 0; i < BTOBB(size); i++) {
		if (i >= (XLOG_HEADER_CYCLE_SIZE / BBSIZE))
			break;
		iclog->ic_header.h_cycle_data[i] = *(__be32 *)dp;
		*(__be32 *)dp = cycle_lsn;
		dp += BBSIZE;
	}

	if (xfs_sb_version_haslogv2(&log->l_mp->m_sb)) {
		xlog_in_core_2_t *xhdr = iclog->ic_data;

		for ( ; i < BTOBB(size); i++) {
			j = i / (XLOG_HEADER_CYCLE_SIZE / BBSIZE);
			k = i % (XLOG_HEADER_CYCLE_SIZE / BBSIZE);
			xhdr[j].hic_xheader.xh_cycle_data[k] = *(__be32 *)dp;
			*(__be32 *)dp = cycle_lsn;
			dp += BBSIZE;
		}

		for (i = 1; i < log->l_iclog_heads; i++)
			xhdr[i].hic_xheader.xh_cycle = cycle_lsn;
	}
}

/*
 * Calculate the checksum for a log buffer.
 *
 * This is a little more complicated than it should be because the various
 * headers and the actual data are non-contiguous.
 */
__le32
xlog_cksum(
	struct xlog		*log,
	struct xlog_rec_header	*rhead,
	char			*dp,
	int			size)
{
	uint32_t		crc;

	/* first generate the crc for the record header ... */
	crc = xfs_start_cksum_update((char *)rhead,
			      sizeof(struct xlog_rec_header),
			      offsetof(struct xlog_rec_header, h_crc));

	/* ... then for additional cycle data for v2 logs ... */
	if (xfs_sb_version_haslogv2(&log->l_mp->m_sb)) {
		union xlog_in_core2 *xhdr = (union xlog_in_core2 *)rhead;
		int		i;
		int		xheads;

		xheads = DIV_ROUND_UP(size, XLOG_HEADER_CYCLE_SIZE);

		for (i = 1; i < xheads; i++) {
			crc = crc32c(crc, &xhdr[i].hic_xheader,
				     sizeof(struct xlog_rec_ext_header));
		}
	}

	/* ... and finally for the payload */
	crc = crc32c(crc, dp, size);

	return xfs_end_cksum(crc);
}

static void
xlog_bio_end_io(
	struct bio		*bio)
{
	struct xlog_in_core	*iclog = bio->bi_private;

	queue_work(iclog->ic_log->l_ioend_workqueue,
		   &iclog->ic_end_io_work);
}

static int
xlog_map_iclog_data(
	struct bio		*bio,
	void			*data,
	size_t			count)
{
	do {
		struct page	*page = kmem_to_page(data);
		unsigned int	off = offset_in_page(data);
		size_t		len = min_t(size_t, count, PAGE_SIZE - off);

		if (bio_add_page(bio, page, len, off) != len)
			return -EIO;

		data += len;
		count -= len;
	} while (count);

	return 0;
}

STATIC void
xlog_write_iclog(
	struct xlog		*log,
	struct xlog_in_core	*iclog,
	uint64_t		bno,
	unsigned int		count,
	bool			need_flush)
{
	ASSERT(bno < log->l_logBBsize);

	/*
	 * We lock the iclogbufs here so that we can serialise against I/O
	 * completion during unmount.  We might be processing a shutdown
	 * triggered during unmount, and that can occur asynchronously to the
	 * unmount thread, and hence we need to ensure that completes before
	 * tearing down the iclogbufs.  Hence we need to hold the buffer lock
	 * across the log IO to archieve that.
	 */
	down(&iclog->ic_sema);
	if (unlikely(iclog->ic_state == XLOG_STATE_IOERROR)) {
		/*
		 * It would seem logical to return EIO here, but we rely on
		 * the log state machine to propagate I/O errors instead of
		 * doing it here.  We kick of the state machine and unlock
		 * the buffer manually, the code needs to be kept in sync
		 * with the I/O completion path.
		 */
		xlog_state_done_syncing(iclog);
		up(&iclog->ic_sema);
		return;
	}

	bio_init(&iclog->ic_bio, iclog->ic_bvec, howmany(count, PAGE_SIZE));
	bio_set_dev(&iclog->ic_bio, log->l_targ->bt_bdev);
	iclog->ic_bio.bi_iter.bi_sector = log->l_logBBstart + bno;
	iclog->ic_bio.bi_end_io = xlog_bio_end_io;
	iclog->ic_bio.bi_private = iclog;

	/*
	 * We use REQ_SYNC | REQ_IDLE here to tell the block layer the are more
	 * IOs coming immediately after this one. This prevents the block layer
	 * writeback throttle from throttling log writes behind background
	 * metadata writeback and causing priority inversions.
	 */
	iclog->ic_bio.bi_opf = REQ_OP_WRITE | REQ_META | REQ_SYNC |
				REQ_IDLE | REQ_FUA;
	if (need_flush)
		iclog->ic_bio.bi_opf |= REQ_PREFLUSH;

	if (xlog_map_iclog_data(&iclog->ic_bio, iclog->ic_data, count)) {
		xfs_force_shutdown(log->l_mp, SHUTDOWN_LOG_IO_ERROR);
		return;
	}
	if (is_vmalloc_addr(iclog->ic_data))
		flush_kernel_vmap_range(iclog->ic_data, count);

	/*
	 * If this log buffer would straddle the end of the log we will have
	 * to split it up into two bios, so that we can continue at the start.
	 */
	if (bno + BTOBB(count) > log->l_logBBsize) {
		struct bio *split;

		split = bio_split(&iclog->ic_bio, log->l_logBBsize - bno,
				  GFP_NOIO, &fs_bio_set);
		bio_chain(split, &iclog->ic_bio);
		submit_bio(split);

		/* restart at logical offset zero for the remainder */
		iclog->ic_bio.bi_iter.bi_sector = log->l_logBBstart;
	}

	submit_bio(&iclog->ic_bio);
}

/*
 * We need to bump cycle number for the part of the iclog that is
 * written to the start of the log. Watch out for the header magic
 * number case, though.
 */
static void
xlog_split_iclog(
	struct xlog		*log,
	void			*data,
	uint64_t		bno,
	unsigned int		count)
{
	unsigned int		split_offset = BBTOB(log->l_logBBsize - bno);
	unsigned int		i;

	for (i = split_offset; i < count; i += BBSIZE) {
		uint32_t cycle = get_unaligned_be32(data + i);

		if (++cycle == XLOG_HEADER_MAGIC_NUM)
			cycle++;
		put_unaligned_be32(cycle, data + i);
	}
}

static int
xlog_calc_iclog_size(
	struct xlog		*log,
	struct xlog_in_core	*iclog,
	uint32_t		*roundoff)
{
	uint32_t		count_init, count;
	bool			use_lsunit;

	use_lsunit = xfs_sb_version_haslogv2(&log->l_mp->m_sb) &&
			log->l_mp->m_sb.sb_logsunit > 1;

	/* Add for LR header */
	count_init = log->l_iclog_hsize + iclog->ic_offset;

	/* Round out the log write size */
	if (use_lsunit) {
		/* we have a v2 stripe unit to use */
		count = XLOG_LSUNITTOB(log, XLOG_BTOLSUNIT(log, count_init));
	} else {
		count = BBTOB(BTOBB(count_init));
	}

	ASSERT(count >= count_init);
	*roundoff = count - count_init;

	if (use_lsunit)
		ASSERT(*roundoff < log->l_mp->m_sb.sb_logsunit);
	else
		ASSERT(*roundoff < BBTOB(1));
	return count;
}

/*
 * Flush out the in-core log (iclog) to the on-disk log in an asynchronous 
 * fashion.  Previously, we should have moved the current iclog
 * ptr in the log to point to the next available iclog.  This allows further
 * write to continue while this code syncs out an iclog ready to go.
 * Before an in-core log can be written out, the data section must be scanned
 * to save away the 1st word of each BBSIZE block into the header.  We replace
 * it with the current cycle count.  Each BBSIZE block is tagged with the
 * cycle count because there in an implicit assumption that drives will
 * guarantee that entire 512 byte blocks get written at once.  In other words,
 * we can't have part of a 512 byte block written and part not written.  By
 * tagging each block, we will know which blocks are valid when recovering
 * after an unclean shutdown.
 *
 * This routine is single threaded on the iclog.  No other thread can be in
 * this routine with the same iclog.  Changing contents of iclog can there-
 * fore be done without grabbing the state machine lock.  Updating the global
 * log will require grabbing the lock though.
 *
 * The entire log manager uses a logical block numbering scheme.  Only
 * xlog_write_iclog knows about the fact that the log may not start with
 * block zero on a given device.
 */
STATIC void
xlog_sync(
	struct xlog		*log,
	struct xlog_in_core	*iclog)
{
	unsigned int		count;		/* byte count of bwrite */
	unsigned int		roundoff;       /* roundoff to BB or stripe */
	uint64_t		bno;
	unsigned int		size;
	bool			need_flush = true, split = false;

	ASSERT(atomic_read(&iclog->ic_refcnt) == 0);

	count = xlog_calc_iclog_size(log, iclog, &roundoff);

	/* move grant heads by roundoff in sync */
	xlog_grant_add_space(log, &log->l_reserve_head.grant, roundoff);
	xlog_grant_add_space(log, &log->l_write_head.grant, roundoff);

	/* put cycle number in every block */
	xlog_pack_data(log, iclog, roundoff); 

	/* real byte length */
	size = iclog->ic_offset;
	if (xfs_sb_version_haslogv2(&log->l_mp->m_sb))
		size += roundoff;
	iclog->ic_header.h_len = cpu_to_be32(size);

	XFS_STATS_INC(log->l_mp, xs_log_writes);
	XFS_STATS_ADD(log->l_mp, xs_log_blocks, BTOBB(count));

	bno = BLOCK_LSN(be64_to_cpu(iclog->ic_header.h_lsn));

	/* Do we need to split this write into 2 parts? */
	if (bno + BTOBB(count) > log->l_logBBsize) {
		xlog_split_iclog(log, &iclog->ic_header, bno, count);
		split = true;
	}

	/* calculcate the checksum */
	iclog->ic_header.h_crc = xlog_cksum(log, &iclog->ic_header,
					    iclog->ic_datap, size);
	/*
	 * Intentionally corrupt the log record CRC based on the error injection
	 * frequency, if defined. This facilitates testing log recovery in the
	 * event of torn writes. Hence, set the IOABORT state to abort the log
	 * write on I/O completion and shutdown the fs. The subsequent mount
	 * detects the bad CRC and attempts to recover.
	 */
#ifdef DEBUG
	if (XFS_TEST_ERROR(false, log->l_mp, XFS_ERRTAG_LOG_BAD_CRC)) {
		iclog->ic_header.h_crc &= cpu_to_le32(0xAAAAAAAA);
		iclog->ic_fail_crc = true;
		xfs_warn(log->l_mp,
	"Intentionally corrupted log record at LSN 0x%llx. Shutdown imminent.",
			 be64_to_cpu(iclog->ic_header.h_lsn));
	}
#endif

	/*
	 * Flush the data device before flushing the log to make sure all meta
	 * data written back from the AIL actually made it to disk before
	 * stamping the new log tail LSN into the log buffer.  For an external
	 * log we need to issue the flush explicitly, and unfortunately
	 * synchronously here; for an internal log we can simply use the block
	 * layer state machine for preflushes.
	 */
	if (log->l_targ != log->l_mp->m_ddev_targp || split) {
		xfs_blkdev_issue_flush(log->l_mp->m_ddev_targp);
		need_flush = false;
	}

	xlog_verify_iclog(log, iclog, count);
	xlog_write_iclog(log, iclog, bno, count, need_flush);
}

/*
 * Deallocate a log structure
 */
STATIC void
xlog_dealloc_log(
	struct xlog	*log)
{
	xlog_in_core_t	*iclog, *next_iclog;
	int		i;

	xlog_cil_destroy(log);

	/*
	 * Cycle all the iclogbuf locks to make sure all log IO completion
	 * is done before we tear down these buffers.
	 */
	iclog = log->l_iclog;
	for (i = 0; i < log->l_iclog_bufs; i++) {
		down(&iclog->ic_sema);
		up(&iclog->ic_sema);
		iclog = iclog->ic_next;
	}

	iclog = log->l_iclog;
	for (i = 0; i < log->l_iclog_bufs; i++) {
		next_iclog = iclog->ic_next;
		kmem_free(iclog->ic_data);
		kmem_free(iclog);
		iclog = next_iclog;
	}

	log->l_mp->m_log = NULL;
	destroy_workqueue(log->l_ioend_workqueue);
	kmem_free(log);
}

/*
 * Update counters atomically now that memcpy is done.
 */
static inline void
xlog_state_finish_copy(
	struct xlog		*log,
	struct xlog_in_core	*iclog,
	int			record_cnt,
	int			copy_bytes)
{
	lockdep_assert_held(&log->l_icloglock);

	be32_add_cpu(&iclog->ic_header.h_num_logops, record_cnt);
	iclog->ic_offset += copy_bytes;
}

/*
 * print out info relating to regions written which consume
 * the reservation
 */
void
xlog_print_tic_res(
	struct xfs_mount	*mp,
	struct xlog_ticket	*ticket)
{
	uint i;
	uint ophdr_spc = ticket->t_res_num_ophdrs * (uint)sizeof(xlog_op_header_t);

	/* match with XLOG_REG_TYPE_* in xfs_log.h */
#define REG_TYPE_STR(type, str)	[XLOG_REG_TYPE_##type] = str
	static char *res_type_str[] = {
	    REG_TYPE_STR(BFORMAT, "bformat"),
	    REG_TYPE_STR(BCHUNK, "bchunk"),
	    REG_TYPE_STR(EFI_FORMAT, "efi_format"),
	    REG_TYPE_STR(EFD_FORMAT, "efd_format"),
	    REG_TYPE_STR(IFORMAT, "iformat"),
	    REG_TYPE_STR(ICORE, "icore"),
	    REG_TYPE_STR(IEXT, "iext"),
	    REG_TYPE_STR(IBROOT, "ibroot"),
	    REG_TYPE_STR(ILOCAL, "ilocal"),
	    REG_TYPE_STR(IATTR_EXT, "iattr_ext"),
	    REG_TYPE_STR(IATTR_BROOT, "iattr_broot"),
	    REG_TYPE_STR(IATTR_LOCAL, "iattr_local"),
	    REG_TYPE_STR(QFORMAT, "qformat"),
	    REG_TYPE_STR(DQUOT, "dquot"),
	    REG_TYPE_STR(QUOTAOFF, "quotaoff"),
	    REG_TYPE_STR(LRHEADER, "LR header"),
	    REG_TYPE_STR(UNMOUNT, "unmount"),
	    REG_TYPE_STR(COMMIT, "commit"),
	    REG_TYPE_STR(TRANSHDR, "trans header"),
	    REG_TYPE_STR(ICREATE, "inode create"),
	    REG_TYPE_STR(RUI_FORMAT, "rui_format"),
	    REG_TYPE_STR(RUD_FORMAT, "rud_format"),
	    REG_TYPE_STR(CUI_FORMAT, "cui_format"),
	    REG_TYPE_STR(CUD_FORMAT, "cud_format"),
	    REG_TYPE_STR(BUI_FORMAT, "bui_format"),
	    REG_TYPE_STR(BUD_FORMAT, "bud_format"),
	};
	BUILD_BUG_ON(ARRAY_SIZE(res_type_str) != XLOG_REG_TYPE_MAX + 1);
#undef REG_TYPE_STR

	xfs_warn(mp, "ticket reservation summary:");
	xfs_warn(mp, "  unit res    = %d bytes",
		 ticket->t_unit_res);
	xfs_warn(mp, "  current res = %d bytes",
		 ticket->t_curr_res);
	xfs_warn(mp, "  total reg   = %u bytes (o/flow = %u bytes)",
		 ticket->t_res_arr_sum, ticket->t_res_o_flow);
	xfs_warn(mp, "  ophdrs      = %u (ophdr space = %u bytes)",
		 ticket->t_res_num_ophdrs, ophdr_spc);
	xfs_warn(mp, "  ophdr + reg = %u bytes",
		 ticket->t_res_arr_sum + ticket->t_res_o_flow + ophdr_spc);
	xfs_warn(mp, "  num regions = %u",
		 ticket->t_res_num);

	for (i = 0; i < ticket->t_res_num; i++) {
		uint r_type = ticket->t_res_arr[i].r_type;
		xfs_warn(mp, "region[%u]: %s - %u bytes", i,
			    ((r_type <= 0 || r_type > XLOG_REG_TYPE_MAX) ?
			    "bad-rtype" : res_type_str[r_type]),
			    ticket->t_res_arr[i].r_len);
	}
}

/*
 * Print a summary of the transaction.
 */
void
xlog_print_trans(
	struct xfs_trans	*tp)
{
	struct xfs_mount	*mp = tp->t_mountp;
	struct xfs_log_item	*lip;

	/* dump core transaction and ticket info */
	xfs_warn(mp, "transaction summary:");
	xfs_warn(mp, "  log res   = %d", tp->t_log_res);
	xfs_warn(mp, "  log count = %d", tp->t_log_count);
	xfs_warn(mp, "  flags     = 0x%x", tp->t_flags);

	xlog_print_tic_res(mp, tp->t_ticket);

	/* dump each log item */
	list_for_each_entry(lip, &tp->t_items, li_trans) {
		struct xfs_log_vec	*lv = lip->li_lv;
		struct xfs_log_iovec	*vec;
		int			i;

		xfs_warn(mp, "log item: ");
		xfs_warn(mp, "  type	= 0x%x", lip->li_type);
		xfs_warn(mp, "  flags	= 0x%lx", lip->li_flags);
		if (!lv)
			continue;
		xfs_warn(mp, "  niovecs	= %d", lv->lv_niovecs);
		xfs_warn(mp, "  size	= %d", lv->lv_size);
		xfs_warn(mp, "  bytes	= %d", lv->lv_bytes);
		xfs_warn(mp, "  buf len	= %d", lv->lv_buf_len);

		/* dump each iovec for the log item */
		vec = lv->lv_iovecp;
		for (i = 0; i < lv->lv_niovecs; i++) {
			int dumplen = min(vec->i_len, 32);

			xfs_warn(mp, "  iovec[%d]", i);
			xfs_warn(mp, "    type	= 0x%x", vec->i_type);
			xfs_warn(mp, "    len	= %d", vec->i_len);
			xfs_warn(mp, "    first %d bytes of iovec[%d]:", dumplen, i);
			xfs_hex_dump(vec->i_addr, dumplen);

			vec++;
		}
	}
}

/*
 * Calculate the potential space needed by the log vector.  We may need a start
 * record, and each region gets its own struct xlog_op_header and may need to be
 * double word aligned.
 */
static int
xlog_write_calc_vec_length(
	struct xlog_ticket	*ticket,
	struct xfs_log_vec	*log_vector,
	bool			need_start_rec)
{
	struct xfs_log_vec	*lv;
	int			headers = need_start_rec ? 1 : 0;
	int			len = 0;
	int			i;

	for (lv = log_vector; lv; lv = lv->lv_next) {
		/* we don't write ordered log vectors */
		if (lv->lv_buf_len == XFS_LOG_VEC_ORDERED)
			continue;

		headers += lv->lv_niovecs;

		for (i = 0; i < lv->lv_niovecs; i++) {
			struct xfs_log_iovec	*vecp = &lv->lv_iovecp[i];

			len += vecp->i_len;
			xlog_tic_add_region(ticket, vecp->i_len, vecp->i_type);
		}
	}

	ticket->t_res_num_ophdrs += headers;
	len += headers * sizeof(struct xlog_op_header);

	return len;
}

static void
xlog_write_start_rec(
	struct xlog_op_header	*ophdr,
	struct xlog_ticket	*ticket)
{
	ophdr->oh_tid	= cpu_to_be32(ticket->t_tid);
	ophdr->oh_clientid = ticket->t_clientid;
	ophdr->oh_len = 0;
	ophdr->oh_flags = XLOG_START_TRANS;
	ophdr->oh_res2 = 0;
}

static xlog_op_header_t *
xlog_write_setup_ophdr(
	struct xlog		*log,
	struct xlog_op_header	*ophdr,
	struct xlog_ticket	*ticket,
	uint			flags)
{
	ophdr->oh_tid = cpu_to_be32(ticket->t_tid);
	ophdr->oh_clientid = ticket->t_clientid;
	ophdr->oh_res2 = 0;

	/* are we copying a commit or unmount record? */
	ophdr->oh_flags = flags;

	/*
	 * We've seen logs corrupted with bad transaction client ids.  This
	 * makes sure that XFS doesn't generate them on.  Turn this into an EIO
	 * and shut down the filesystem.
	 */
	switch (ophdr->oh_clientid)  {
	case XFS_TRANSACTION:
	case XFS_VOLUME:
	case XFS_LOG:
		break;
	default:
		xfs_warn(log->l_mp,
			"Bad XFS transaction clientid 0x%x in ticket "PTR_FMT,
			ophdr->oh_clientid, ticket);
		return NULL;
	}

	return ophdr;
}

/*
 * Set up the parameters of the region copy into the log. This has
 * to handle region write split across multiple log buffers - this
 * state is kept external to this function so that this code can
 * be written in an obvious, self documenting manner.
 */
static int
xlog_write_setup_copy(
	struct xlog_ticket	*ticket,
	struct xlog_op_header	*ophdr,
	int			space_available,
	int			space_required,
	int			*copy_off,
	int			*copy_len,
	int			*last_was_partial_copy,
	int			*bytes_consumed)
{
	int			still_to_copy;

	still_to_copy = space_required - *bytes_consumed;
	*copy_off = *bytes_consumed;

	if (still_to_copy <= space_available) {
		/* write of region completes here */
		*copy_len = still_to_copy;
		ophdr->oh_len = cpu_to_be32(*copy_len);
		if (*last_was_partial_copy)
			ophdr->oh_flags |= (XLOG_END_TRANS|XLOG_WAS_CONT_TRANS);
		*last_was_partial_copy = 0;
		*bytes_consumed = 0;
		return 0;
	}

	/* partial write of region, needs extra log op header reservation */
	*copy_len = space_available;
	ophdr->oh_len = cpu_to_be32(*copy_len);
	ophdr->oh_flags |= XLOG_CONTINUE_TRANS;
	if (*last_was_partial_copy)
		ophdr->oh_flags |= XLOG_WAS_CONT_TRANS;
	*bytes_consumed += *copy_len;
	(*last_was_partial_copy)++;

	/* account for new log op header */
	ticket->t_curr_res -= sizeof(struct xlog_op_header);
	ticket->t_res_num_ophdrs++;

	return sizeof(struct xlog_op_header);
}

static int
xlog_write_copy_finish(
	struct xlog		*log,
	struct xlog_in_core	*iclog,
	uint			flags,
	int			*record_cnt,
	int			*data_cnt,
	int			*partial_copy,
	int			*partial_copy_len,
	int			log_offset,
	struct xlog_in_core	**commit_iclog)
{
	int			error;

	if (*partial_copy) {
		/*
		 * This iclog has already been marked WANT_SYNC by
		 * xlog_state_get_iclog_space.
		 */
		spin_lock(&log->l_icloglock);
		xlog_state_finish_copy(log, iclog, *record_cnt, *data_cnt);
		*record_cnt = 0;
		*data_cnt = 0;
		goto release_iclog;
	}

	*partial_copy = 0;
	*partial_copy_len = 0;

	if (iclog->ic_size - log_offset <= sizeof(xlog_op_header_t)) {
		/* no more space in this iclog - push it. */
		spin_lock(&log->l_icloglock);
		xlog_state_finish_copy(log, iclog, *record_cnt, *data_cnt);
		*record_cnt = 0;
		*data_cnt = 0;

		if (iclog->ic_state == XLOG_STATE_ACTIVE)
			xlog_state_switch_iclogs(log, iclog, 0);
		else
			ASSERT(iclog->ic_state == XLOG_STATE_WANT_SYNC ||
			       iclog->ic_state == XLOG_STATE_IOERROR);
		if (!commit_iclog)
			goto release_iclog;
		spin_unlock(&log->l_icloglock);
		ASSERT(flags & XLOG_COMMIT_TRANS);
		*commit_iclog = iclog;
	}

	return 0;

release_iclog:
	error = xlog_state_release_iclog(log, iclog);
	spin_unlock(&log->l_icloglock);
	return error;
}

/*
 * Write some region out to in-core log
 *
 * This will be called when writing externally provided regions or when
 * writing out a commit record for a given transaction.
 *
 * General algorithm:
 *	1. Find total length of this write.  This may include adding to the
 *		lengths passed in.
 *	2. Check whether we violate the tickets reservation.
 *	3. While writing to this iclog
 *	    A. Reserve as much space in this iclog as can get
 *	    B. If this is first write, save away start lsn
 *	    C. While writing this region:
 *		1. If first write of transaction, write start record
 *		2. Write log operation header (header per region)
 *		3. Find out if we can fit entire region into this iclog
 *		4. Potentially, verify destination memcpy ptr
 *		5. Memcpy (partial) region
 *		6. If partial copy, release iclog; otherwise, continue
 *			copying more regions into current iclog
 *	4. Mark want sync bit (in simulation mode)
 *	5. Release iclog for potential flush to on-disk log.
 *
 * ERRORS:
 * 1.	Panic if reservation is overrun.  This should never happen since
 *	reservation amounts are generated internal to the filesystem.
 * NOTES:
 * 1. Tickets are single threaded data structures.
 * 2. The XLOG_END_TRANS & XLOG_CONTINUE_TRANS flags are passed down to the
 *	syncing routine.  When a single log_write region needs to span
 *	multiple in-core logs, the XLOG_CONTINUE_TRANS bit should be set
 *	on all log operation writes which don't contain the end of the
 *	region.  The XLOG_END_TRANS bit is used for the in-core log
 *	operation which contains the end of the continued log_write region.
 * 3. When xlog_state_get_iclog_space() grabs the rest of the current iclog,
 *	we don't really know exactly how much space will be used.  As a result,
 *	we don't update ic_offset until the end when we know exactly how many
 *	bytes have been written out.
 */
int
xlog_write(
	struct xlog		*log,
	struct xfs_log_vec	*log_vector,
	struct xlog_ticket	*ticket,
	xfs_lsn_t		*start_lsn,
	struct xlog_in_core	**commit_iclog,
	uint			flags,
	bool			need_start_rec)
{
	struct xlog_in_core	*iclog = NULL;
	struct xfs_log_vec	*lv = log_vector;
	struct xfs_log_iovec	*vecp = lv->lv_iovecp;
	int			index = 0;
	int			len;
	int			partial_copy = 0;
	int			partial_copy_len = 0;
	int			contwr = 0;
	int			record_cnt = 0;
	int			data_cnt = 0;
	int			error = 0;

	/*
	 * If this is a commit or unmount transaction, we don't need a start
	 * record to be written.  We do, however, have to account for the
	 * commit or unmount header that gets written. Hence we always have
	 * to account for an extra xlog_op_header here.
	 */
	ticket->t_curr_res -= sizeof(struct xlog_op_header);
	if (ticket->t_curr_res < 0) {
		xfs_alert_tag(log->l_mp, XFS_PTAG_LOGRES,
		     "ctx ticket reservation ran out. Need to up reservation");
		xlog_print_tic_res(log->l_mp, ticket);
		xfs_force_shutdown(log->l_mp, SHUTDOWN_LOG_IO_ERROR);
	}

	len = xlog_write_calc_vec_length(ticket, log_vector, need_start_rec);
	*start_lsn = 0;
	while (lv && (!lv->lv_niovecs || index < lv->lv_niovecs)) {
		void		*ptr;
		int		log_offset;

		error = xlog_state_get_iclog_space(log, len, &iclog, ticket,
						   &contwr, &log_offset);
		if (error)
			return error;

		ASSERT(log_offset <= iclog->ic_size - 1);
		ptr = iclog->ic_datap + log_offset;

		/* start_lsn is the first lsn written to. That's all we need. */
		if (!*start_lsn)
			*start_lsn = be64_to_cpu(iclog->ic_header.h_lsn);

		/*
		 * This loop writes out as many regions as can fit in the amount
		 * of space which was allocated by xlog_state_get_iclog_space().
		 */
		while (lv && (!lv->lv_niovecs || index < lv->lv_niovecs)) {
			struct xfs_log_iovec	*reg;
			struct xlog_op_header	*ophdr;
			int			copy_len;
			int			copy_off;
			bool			ordered = false;

			/* ordered log vectors have no regions to write */
			if (lv->lv_buf_len == XFS_LOG_VEC_ORDERED) {
				ASSERT(lv->lv_niovecs == 0);
				ordered = true;
				goto next_lv;
			}

			reg = &vecp[index];
			ASSERT(reg->i_len % sizeof(int32_t) == 0);
			ASSERT((unsigned long)ptr % sizeof(int32_t) == 0);

			/*
			 * Before we start formatting log vectors, we need to
			 * write a start record. Only do this for the first
			 * iclog we write to.
			 */
			if (need_start_rec) {
				xlog_write_start_rec(ptr, ticket);
				xlog_write_adv_cnt(&ptr, &len, &log_offset,
						sizeof(struct xlog_op_header));
			}

			ophdr = xlog_write_setup_ophdr(log, ptr, ticket, flags);
			if (!ophdr)
				return -EIO;

			xlog_write_adv_cnt(&ptr, &len, &log_offset,
					   sizeof(struct xlog_op_header));

			len += xlog_write_setup_copy(ticket, ophdr,
						     iclog->ic_size-log_offset,
						     reg->i_len,
						     &copy_off, &copy_len,
						     &partial_copy,
						     &partial_copy_len);
			xlog_verify_dest_ptr(log, ptr);

			/*
			 * Copy region.
			 *
			 * Unmount records just log an opheader, so can have
			 * empty payloads with no data region to copy. Hence we
			 * only copy the payload if the vector says it has data
			 * to copy.
			 */
			ASSERT(copy_len >= 0);
			if (copy_len > 0) {
				memcpy(ptr, reg->i_addr + copy_off, copy_len);
				xlog_write_adv_cnt(&ptr, &len, &log_offset,
						   copy_len);
			}
			copy_len += sizeof(struct xlog_op_header);
			record_cnt++;
			if (need_start_rec) {
				copy_len += sizeof(struct xlog_op_header);
				record_cnt++;
				need_start_rec = false;
			}
			data_cnt += contwr ? copy_len : 0;

			error = xlog_write_copy_finish(log, iclog, flags,
						       &record_cnt, &data_cnt,
						       &partial_copy,
						       &partial_copy_len,
						       log_offset,
						       commit_iclog);
			if (error)
				return error;

			/*
			 * if we had a partial copy, we need to get more iclog
			 * space but we don't want to increment the region
			 * index because there is still more is this region to
			 * write.
			 *
			 * If we completed writing this region, and we flushed
			 * the iclog (indicated by resetting of the record
			 * count), then we also need to get more log space. If
			 * this was the last record, though, we are done and
			 * can just return.
			 */
			if (partial_copy)
				break;

			if (++index == lv->lv_niovecs) {
next_lv:
				lv = lv->lv_next;
				index = 0;
				if (lv)
					vecp = lv->lv_iovecp;
			}
			if (record_cnt == 0 && !ordered) {
				if (!lv)
					return 0;
				break;
			}
		}
	}

	ASSERT(len == 0);

	spin_lock(&log->l_icloglock);
	xlog_state_finish_copy(log, iclog, record_cnt, data_cnt);
	if (commit_iclog) {
		ASSERT(flags & XLOG_COMMIT_TRANS);
		*commit_iclog = iclog;
	} else {
		error = xlog_state_release_iclog(log, iclog);
	}
	spin_unlock(&log->l_icloglock);

	return error;
}

static void
xlog_state_activate_iclog(
	struct xlog_in_core	*iclog,
	int			*iclogs_changed)
{
	ASSERT(list_empty_careful(&iclog->ic_callbacks));

	/*
	 * If the number of ops in this iclog indicate it just contains the
	 * dummy transaction, we can change state into IDLE (the second time
	 * around). Otherwise we should change the state into NEED a dummy.
	 * We don't need to cover the dummy.
	 */
	if (*iclogs_changed == 0 &&
	    iclog->ic_header.h_num_logops == cpu_to_be32(XLOG_COVER_OPS)) {
		*iclogs_changed = 1;
	} else {
		/*
		 * We have two dirty iclogs so start over.  This could also be
		 * num of ops indicating this is not the dummy going out.
		 */
		*iclogs_changed = 2;
	}

	iclog->ic_state	= XLOG_STATE_ACTIVE;
	iclog->ic_offset = 0;
	iclog->ic_header.h_num_logops = 0;
	memset(iclog->ic_header.h_cycle_data, 0,
		sizeof(iclog->ic_header.h_cycle_data));
	iclog->ic_header.h_lsn = 0;
}

/*
 * Loop through all iclogs and mark all iclogs currently marked DIRTY as
 * ACTIVE after iclog I/O has completed.
 */
static void
xlog_state_activate_iclogs(
	struct xlog		*log,
	int			*iclogs_changed)
{
	struct xlog_in_core	*iclog = log->l_iclog;

	do {
		if (iclog->ic_state == XLOG_STATE_DIRTY)
			xlog_state_activate_iclog(iclog, iclogs_changed);
		/*
		 * The ordering of marking iclogs ACTIVE must be maintained, so
		 * an iclog doesn't become ACTIVE beyond one that is SYNCING.
		 */
		else if (iclog->ic_state != XLOG_STATE_ACTIVE)
			break;
	} while ((iclog = iclog->ic_next) != log->l_iclog);
}

static int
xlog_covered_state(
	int			prev_state,
	int			iclogs_changed)
{
	/*
	 * We usually go to NEED. But we go to NEED2 if the changed indicates we
	 * are done writing the dummy record.  If we are done with the second
	 * dummy recored (DONE2), then we go to IDLE.
	 */
	switch (prev_state) {
	case XLOG_STATE_COVER_IDLE:
	case XLOG_STATE_COVER_NEED:
	case XLOG_STATE_COVER_NEED2:
		break;
	case XLOG_STATE_COVER_DONE:
		if (iclogs_changed == 1)
			return XLOG_STATE_COVER_NEED2;
		break;
	case XLOG_STATE_COVER_DONE2:
		if (iclogs_changed == 1)
			return XLOG_STATE_COVER_IDLE;
		break;
	default:
		ASSERT(0);
	}

	return XLOG_STATE_COVER_NEED;
}

STATIC void
xlog_state_clean_iclog(
	struct xlog		*log,
	struct xlog_in_core	*dirty_iclog)
{
	int			iclogs_changed = 0;

	dirty_iclog->ic_state = XLOG_STATE_DIRTY;

	xlog_state_activate_iclogs(log, &iclogs_changed);
	wake_up_all(&dirty_iclog->ic_force_wait);

	if (iclogs_changed) {
		log->l_covered_state = xlog_covered_state(log->l_covered_state,
				iclogs_changed);
	}
}

STATIC xfs_lsn_t
xlog_get_lowest_lsn(
	struct xlog		*log)
{
	struct xlog_in_core	*iclog = log->l_iclog;
	xfs_lsn_t		lowest_lsn = 0, lsn;

	do {
		if (iclog->ic_state == XLOG_STATE_ACTIVE ||
		    iclog->ic_state == XLOG_STATE_DIRTY)
			continue;

		lsn = be64_to_cpu(iclog->ic_header.h_lsn);
		if ((lsn && !lowest_lsn) || XFS_LSN_CMP(lsn, lowest_lsn) < 0)
			lowest_lsn = lsn;
	} while ((iclog = iclog->ic_next) != log->l_iclog);

	return lowest_lsn;
}

/*
 * Completion of a iclog IO does not imply that a transaction has completed, as
 * transactions can be large enough to span many iclogs. We cannot change the
 * tail of the log half way through a transaction as this may be the only
 * transaction in the log and moving the tail to point to the middle of it
 * will prevent recovery from finding the start of the transaction. Hence we
 * should only update the last_sync_lsn if this iclog contains transaction
 * completion callbacks on it.
 *
 * We have to do this before we drop the icloglock to ensure we are the only one
 * that can update it.
 *
 * If we are moving the last_sync_lsn forwards, we also need to ensure we kick
 * the reservation grant head pushing. This is due to the fact that the push
 * target is bound by the current last_sync_lsn value. Hence if we have a large
 * amount of log space bound up in this committing transaction then the
 * last_sync_lsn value may be the limiting factor preventing tail pushing from
 * freeing space in the log. Hence once we've updated the last_sync_lsn we
 * should push the AIL to ensure the push target (and hence the grant head) is
 * no longer bound by the old log head location and can move forwards and make
 * progress again.
 */
static void
xlog_state_set_callback(
	struct xlog		*log,
	struct xlog_in_core	*iclog,
	xfs_lsn_t		header_lsn)
{
	iclog->ic_state = XLOG_STATE_CALLBACK;

	ASSERT(XFS_LSN_CMP(atomic64_read(&log->l_last_sync_lsn),
			   header_lsn) <= 0);

	if (list_empty_careful(&iclog->ic_callbacks))
		return;

	atomic64_set(&log->l_last_sync_lsn, header_lsn);
	xlog_grant_push_ail(log, 0);
}

/*
 * Return true if we need to stop processing, false to continue to the next
 * iclog. The caller will need to run callbacks if the iclog is returned in the
 * XLOG_STATE_CALLBACK state.
 */
static bool
xlog_state_iodone_process_iclog(
	struct xlog		*log,
	struct xlog_in_core	*iclog,
	bool			*ioerror)
{
	xfs_lsn_t		lowest_lsn;
	xfs_lsn_t		header_lsn;

	switch (iclog->ic_state) {
	case XLOG_STATE_ACTIVE:
	case XLOG_STATE_DIRTY:
		/*
		 * Skip all iclogs in the ACTIVE & DIRTY states:
		 */
		return false;
	case XLOG_STATE_IOERROR:
		/*
		 * Between marking a filesystem SHUTDOWN and stopping the log,
		 * we do flush all iclogs to disk (if there wasn't a log I/O
		 * error). So, we do want things to go smoothly in case of just
		 * a SHUTDOWN w/o a LOG_IO_ERROR.
		 */
		*ioerror = true;
		return false;
	case XLOG_STATE_DONE_SYNC:
		/*
		 * Now that we have an iclog that is in the DONE_SYNC state, do
		 * one more check here to see if we have chased our tail around.
		 * If this is not the lowest lsn iclog, then we will leave it
		 * for another completion to process.
		 */
		header_lsn = be64_to_cpu(iclog->ic_header.h_lsn);
		lowest_lsn = xlog_get_lowest_lsn(log);
		if (lowest_lsn && XFS_LSN_CMP(lowest_lsn, header_lsn) < 0)
			return false;
		xlog_state_set_callback(log, iclog, header_lsn);
		return false;
	default:
		/*
		 * Can only perform callbacks in order.  Since this iclog is not
		 * in the DONE_SYNC state, we skip the rest and just try to
		 * clean up.
		 */
		return true;
	}
}

/*
 * Keep processing entries in the iclog callback list until we come around and
 * it is empty.  We need to atomically see that the list is empty and change the
 * state to DIRTY so that we don't miss any more callbacks being added.
 *
 * This function is called with the icloglock held and returns with it held. We
 * drop it while running callbacks, however, as holding it over thousands of
 * callbacks is unnecessary and causes excessive contention if we do.
 */
static void
xlog_state_do_iclog_callbacks(
	struct xlog		*log,
	struct xlog_in_core	*iclog)
		__releases(&log->l_icloglock)
		__acquires(&log->l_icloglock)
{
	spin_unlock(&log->l_icloglock);
	spin_lock(&iclog->ic_callback_lock);
	while (!list_empty(&iclog->ic_callbacks)) {
		LIST_HEAD(tmp);

		list_splice_init(&iclog->ic_callbacks, &tmp);

		spin_unlock(&iclog->ic_callback_lock);
		xlog_cil_process_committed(&tmp);
		spin_lock(&iclog->ic_callback_lock);
	}

	/*
	 * Pick up the icloglock while still holding the callback lock so we
	 * serialise against anyone trying to add more callbacks to this iclog
	 * now we've finished processing.
	 */
	spin_lock(&log->l_icloglock);
	spin_unlock(&iclog->ic_callback_lock);
}

STATIC void
xlog_state_do_callback(
	struct xlog		*log)
{
	struct xlog_in_core	*iclog;
	struct xlog_in_core	*first_iclog;
	bool			cycled_icloglock;
	bool			ioerror;
	int			flushcnt = 0;
	int			repeats = 0;

	spin_lock(&log->l_icloglock);
	do {
		/*
		 * Scan all iclogs starting with the one pointed to by the
		 * log.  Reset this starting point each time the log is
		 * unlocked (during callbacks).
		 *
		 * Keep looping through iclogs until one full pass is made
		 * without running any callbacks.
		 */
		first_iclog = log->l_iclog;
		iclog = log->l_iclog;
		cycled_icloglock = false;
		ioerror = false;
		repeats++;

		do {
			if (xlog_state_iodone_process_iclog(log, iclog,
							&ioerror))
				break;

			if (iclog->ic_state != XLOG_STATE_CALLBACK &&
			    iclog->ic_state != XLOG_STATE_IOERROR) {
				iclog = iclog->ic_next;
				continue;
			}

			/*
			 * Running callbacks will drop the icloglock which means
			 * we'll have to run at least one more complete loop.
			 */
			cycled_icloglock = true;
			xlog_state_do_iclog_callbacks(log, iclog);
			if (XLOG_FORCED_SHUTDOWN(log))
				wake_up_all(&iclog->ic_force_wait);
			else
				xlog_state_clean_iclog(log, iclog);
			iclog = iclog->ic_next;
		} while (first_iclog != iclog);

		if (repeats > 5000) {
			flushcnt += repeats;
			repeats = 0;
			xfs_warn(log->l_mp,
				"%s: possible infinite loop (%d iterations)",
				__func__, flushcnt);
		}
	} while (!ioerror && cycled_icloglock);

	if (log->l_iclog->ic_state == XLOG_STATE_ACTIVE ||
	    log->l_iclog->ic_state == XLOG_STATE_IOERROR)
		wake_up_all(&log->l_flush_wait);

	spin_unlock(&log->l_icloglock);
}


/*
 * Finish transitioning this iclog to the dirty state.
 *
 * Make sure that we completely execute this routine only when this is
 * the last call to the iclog.  There is a good chance that iclog flushes,
 * when we reach the end of the physical log, get turned into 2 separate
 * calls to bwrite.  Hence, one iclog flush could generate two calls to this
 * routine.  By using the reference count bwritecnt, we guarantee that only
 * the second completion goes through.
 *
 * Callbacks could take time, so they are done outside the scope of the
 * global state machine log lock.
 */
STATIC void
xlog_state_done_syncing(
	struct xlog_in_core	*iclog)
{
	struct xlog		*log = iclog->ic_log;

	spin_lock(&log->l_icloglock);
	ASSERT(atomic_read(&iclog->ic_refcnt) == 0);

	/*
	 * If we got an error, either on the first buffer, or in the case of
	 * split log writes, on the second, we shut down the file system and
	 * no iclogs should ever be attempted to be written to disk again.
	 */
	if (!XLOG_FORCED_SHUTDOWN(log)) {
		ASSERT(iclog->ic_state == XLOG_STATE_SYNCING);
		iclog->ic_state = XLOG_STATE_DONE_SYNC;
	}

	/*
	 * Someone could be sleeping prior to writing out the next
	 * iclog buffer, we wake them all, one will get to do the
	 * I/O, the others get to wait for the result.
	 */
	wake_up_all(&iclog->ic_write_wait);
	spin_unlock(&log->l_icloglock);
	xlog_state_do_callback(log);
}

/*
 * If the head of the in-core log ring is not (ACTIVE or DIRTY), then we must
 * sleep.  We wait on the flush queue on the head iclog as that should be
 * the first iclog to complete flushing. Hence if all iclogs are syncing,
 * we will wait here and all new writes will sleep until a sync completes.
 *
 * The in-core logs are used in a circular fashion. They are not used
 * out-of-order even when an iclog past the head is free.
 *
 * return:
 *	* log_offset where xlog_write() can start writing into the in-core
 *		log's data space.
 *	* in-core log pointer to which xlog_write() should write.
 *	* boolean indicating this is a continued write to an in-core log.
 *		If this is the last write, then the in-core log's offset field
 *		needs to be incremented, depending on the amount of data which
 *		is copied.
 */
STATIC int
xlog_state_get_iclog_space(
	struct xlog		*log,
	int			len,
	struct xlog_in_core	**iclogp,
	struct xlog_ticket	*ticket,
	int			*continued_write,
	int			*logoffsetp)
{
	int		  log_offset;
	xlog_rec_header_t *head;
	xlog_in_core_t	  *iclog;

restart:
	spin_lock(&log->l_icloglock);
	if (XLOG_FORCED_SHUTDOWN(log)) {
		spin_unlock(&log->l_icloglock);
		return -EIO;
	}

	iclog = log->l_iclog;
	if (iclog->ic_state != XLOG_STATE_ACTIVE) {
		XFS_STATS_INC(log->l_mp, xs_log_noiclogs);

		/* Wait for log writes to have flushed */
		xlog_wait(&log->l_flush_wait, &log->l_icloglock);
		goto restart;
	}

	head = &iclog->ic_header;

	atomic_inc(&iclog->ic_refcnt);	/* prevents sync */
	log_offset = iclog->ic_offset;

	/* On the 1st write to an iclog, figure out lsn.  This works
	 * if iclogs marked XLOG_STATE_WANT_SYNC always write out what they are
	 * committing to.  If the offset is set, that's how many blocks
	 * must be written.
	 */
	if (log_offset == 0) {
		ticket->t_curr_res -= log->l_iclog_hsize;
		xlog_tic_add_region(ticket,
				    log->l_iclog_hsize,
				    XLOG_REG_TYPE_LRHEADER);
		head->h_cycle = cpu_to_be32(log->l_curr_cycle);
		head->h_lsn = cpu_to_be64(
			xlog_assign_lsn(log->l_curr_cycle, log->l_curr_block));
		ASSERT(log->l_curr_block >= 0);
	}

	/* If there is enough room to write everything, then do it.  Otherwise,
	 * claim the rest of the region and make sure the XLOG_STATE_WANT_SYNC
	 * bit is on, so this will get flushed out.  Don't update ic_offset
	 * until you know exactly how many bytes get copied.  Therefore, wait
	 * until later to update ic_offset.
	 *
	 * xlog_write() algorithm assumes that at least 2 xlog_op_header_t's
	 * can fit into remaining data section.
	 */
	if (iclog->ic_size - iclog->ic_offset < 2*sizeof(xlog_op_header_t)) {
		int		error = 0;

		xlog_state_switch_iclogs(log, iclog, iclog->ic_size);

		/*
		 * If we are the only one writing to this iclog, sync it to
		 * disk.  We need to do an atomic compare and decrement here to
		 * avoid racing with concurrent atomic_dec_and_lock() calls in
		 * xlog_state_release_iclog() when there is more than one
		 * reference to the iclog.
		 */
		if (!atomic_add_unless(&iclog->ic_refcnt, -1, 1))
			error = xlog_state_release_iclog(log, iclog);
		spin_unlock(&log->l_icloglock);
		if (error)
			return error;
		goto restart;
	}

	/* Do we have enough room to write the full amount in the remainder
	 * of this iclog?  Or must we continue a write on the next iclog and
	 * mark this iclog as completely taken?  In the case where we switch
	 * iclogs (to mark it taken), this particular iclog will release/sync
	 * to disk in xlog_write().
	 */
	if (len <= iclog->ic_size - iclog->ic_offset) {
		*continued_write = 0;
		iclog->ic_offset += len;
	} else {
		*continued_write = 1;
		xlog_state_switch_iclogs(log, iclog, iclog->ic_size);
	}
	*iclogp = iclog;

	ASSERT(iclog->ic_offset <= iclog->ic_size);
	spin_unlock(&log->l_icloglock);

	*logoffsetp = log_offset;
	return 0;
}

/*
 * The first cnt-1 times a ticket goes through here we don't need to move the
 * grant write head because the permanent reservation has reserved cnt times the
 * unit amount.  Release part of current permanent unit reservation and reset
 * current reservation to be one units worth.  Also move grant reservation head
 * forward.
 */
void
xfs_log_ticket_regrant(
	struct xlog		*log,
	struct xlog_ticket	*ticket)
{
	trace_xfs_log_ticket_regrant(log, ticket);

	if (ticket->t_cnt > 0)
		ticket->t_cnt--;

	xlog_grant_sub_space(log, &log->l_reserve_head.grant,
					ticket->t_curr_res);
	xlog_grant_sub_space(log, &log->l_write_head.grant,
					ticket->t_curr_res);
	ticket->t_curr_res = ticket->t_unit_res;
	xlog_tic_reset_res(ticket);

	trace_xfs_log_ticket_regrant_sub(log, ticket);

	/* just return if we still have some of the pre-reserved space */
	if (!ticket->t_cnt) {
		xlog_grant_add_space(log, &log->l_reserve_head.grant,
				     ticket->t_unit_res);
		trace_xfs_log_ticket_regrant_exit(log, ticket);

		ticket->t_curr_res = ticket->t_unit_res;
		xlog_tic_reset_res(ticket);
	}

	xfs_log_ticket_put(ticket);
}

/*
 * Give back the space left from a reservation.
 *
 * All the information we need to make a correct determination of space left
 * is present.  For non-permanent reservations, things are quite easy.  The
 * count should have been decremented to zero.  We only need to deal with the
 * space remaining in the current reservation part of the ticket.  If the
 * ticket contains a permanent reservation, there may be left over space which
 * needs to be released.  A count of N means that N-1 refills of the current
 * reservation can be done before we need to ask for more space.  The first
 * one goes to fill up the first current reservation.  Once we run out of
 * space, the count will stay at zero and the only space remaining will be
 * in the current reservation field.
 */
void
xfs_log_ticket_ungrant(
	struct xlog		*log,
	struct xlog_ticket	*ticket)
{
	int			bytes;

	trace_xfs_log_ticket_ungrant(log, ticket);

	if (ticket->t_cnt > 0)
		ticket->t_cnt--;

	trace_xfs_log_ticket_ungrant_sub(log, ticket);

	/*
	 * If this is a permanent reservation ticket, we may be able to free
	 * up more space based on the remaining count.
	 */
	bytes = ticket->t_curr_res;
	if (ticket->t_cnt > 0) {
		ASSERT(ticket->t_flags & XLOG_TIC_PERM_RESERV);
		bytes += ticket->t_unit_res*ticket->t_cnt;
	}

	xlog_grant_sub_space(log, &log->l_reserve_head.grant, bytes);
	xlog_grant_sub_space(log, &log->l_write_head.grant, bytes);

	trace_xfs_log_ticket_ungrant_exit(log, ticket);

	xfs_log_space_wake(log->l_mp);
	xfs_log_ticket_put(ticket);
}

/*
 * This routine will mark the current iclog in the ring as WANT_SYNC and move
 * the current iclog pointer to the next iclog in the ring.
 */
STATIC void
xlog_state_switch_iclogs(
	struct xlog		*log,
	struct xlog_in_core	*iclog,
	int			eventual_size)
{
	ASSERT(iclog->ic_state == XLOG_STATE_ACTIVE);
	assert_spin_locked(&log->l_icloglock);

	if (!eventual_size)
		eventual_size = iclog->ic_offset;
	iclog->ic_state = XLOG_STATE_WANT_SYNC;
	iclog->ic_header.h_prev_block = cpu_to_be32(log->l_prev_block);
	log->l_prev_block = log->l_curr_block;
	log->l_prev_cycle = log->l_curr_cycle;

	/* roll log?: ic_offset changed later */
	log->l_curr_block += BTOBB(eventual_size)+BTOBB(log->l_iclog_hsize);

	/* Round up to next log-sunit */
	if (xfs_sb_version_haslogv2(&log->l_mp->m_sb) &&
	    log->l_mp->m_sb.sb_logsunit > 1) {
		uint32_t sunit_bb = BTOBB(log->l_mp->m_sb.sb_logsunit);
		log->l_curr_block = roundup(log->l_curr_block, sunit_bb);
	}

	if (log->l_curr_block >= log->l_logBBsize) {
		/*
		 * Rewind the current block before the cycle is bumped to make
		 * sure that the combined LSN never transiently moves forward
		 * when the log wraps to the next cycle. This is to support the
		 * unlocked sample of these fields from xlog_valid_lsn(). Most
		 * other cases should acquire l_icloglock.
		 */
		log->l_curr_block -= log->l_logBBsize;
		ASSERT(log->l_curr_block >= 0);
		smp_wmb();
		log->l_curr_cycle++;
		if (log->l_curr_cycle == XLOG_HEADER_MAGIC_NUM)
			log->l_curr_cycle++;
	}
	ASSERT(iclog == log->l_iclog);
	log->l_iclog = iclog->ic_next;
}

/*
 * Write out all data in the in-core log as of this exact moment in time.
 *
 * Data may be written to the in-core log during this call.  However,
 * we don't guarantee this data will be written out.  A change from past
 * implementation means this routine will *not* write out zero length LRs.
 *
 * Basically, we try and perform an intelligent scan of the in-core logs.
 * If we determine there is no flushable data, we just return.  There is no
 * flushable data if:
 *
 *	1. the current iclog is active and has no data; the previous iclog
 *		is in the active or dirty state.
 *	2. the current iclog is drity, and the previous iclog is in the
 *		active or dirty state.
 *
 * We may sleep if:
 *
 *	1. the current iclog is not in the active nor dirty state.
 *	2. the current iclog dirty, and the previous iclog is not in the
 *		active nor dirty state.
 *	3. the current iclog is active, and there is another thread writing
 *		to this particular iclog.
 *	4. a) the current iclog is active and has no other writers
 *	   b) when we return from flushing out this iclog, it is still
 *		not in the active nor dirty state.
 */
int
xfs_log_force(
	struct xfs_mount	*mp,
	uint			flags)
{
	struct xlog		*log = mp->m_log;
	struct xlog_in_core	*iclog;
	xfs_lsn_t		lsn;

	XFS_STATS_INC(mp, xs_log_force);
	trace_xfs_log_force(mp, 0, _RET_IP_);

	xlog_cil_force(log);

	spin_lock(&log->l_icloglock);
	iclog = log->l_iclog;
	if (iclog->ic_state == XLOG_STATE_IOERROR)
		goto out_error;

	if (iclog->ic_state == XLOG_STATE_DIRTY ||
	    (iclog->ic_state == XLOG_STATE_ACTIVE &&
	     atomic_read(&iclog->ic_refcnt) == 0 && iclog->ic_offset == 0)) {
		/*
		 * If the head is dirty or (active and empty), then we need to
		 * look at the previous iclog.
		 *
		 * If the previous iclog is active or dirty we are done.  There
		 * is nothing to sync out. Otherwise, we attach ourselves to the
		 * previous iclog and go to sleep.
		 */
		iclog = iclog->ic_prev;
	} else if (iclog->ic_state == XLOG_STATE_ACTIVE) {
		if (atomic_read(&iclog->ic_refcnt) == 0) {
			/*
			 * We are the only one with access to this iclog.
			 *
			 * Flush it out now.  There should be a roundoff of zero
			 * to show that someone has already taken care of the
			 * roundoff from the previous sync.
			 */
			atomic_inc(&iclog->ic_refcnt);
			lsn = be64_to_cpu(iclog->ic_header.h_lsn);
			xlog_state_switch_iclogs(log, iclog, 0);
			if (xlog_state_release_iclog(log, iclog))
				goto out_error;

			if (be64_to_cpu(iclog->ic_header.h_lsn) != lsn)
				goto out_unlock;
		} else {
			/*
			 * Someone else is writing to this iclog.
			 *
			 * Use its call to flush out the data.  However, the
			 * other thread may not force out this LR, so we mark
			 * it WANT_SYNC.
			 */
			xlog_state_switch_iclogs(log, iclog, 0);
		}
	} else {
		/*
		 * If the head iclog is not active nor dirty, we just attach
		 * ourselves to the head and go to sleep if necessary.
		 */
		;
	}

	if (flags & XFS_LOG_SYNC)
		return xlog_wait_on_iclog(iclog);
out_unlock:
	spin_unlock(&log->l_icloglock);
	return 0;
out_error:
	spin_unlock(&log->l_icloglock);
	return -EIO;
}

static int
__xfs_log_force_lsn(
	struct xfs_mount	*mp,
	xfs_lsn_t		lsn,
	uint			flags,
	int			*log_flushed,
	bool			already_slept)
{
	struct xlog		*log = mp->m_log;
	struct xlog_in_core	*iclog;

	spin_lock(&log->l_icloglock);
	iclog = log->l_iclog;
	if (iclog->ic_state == XLOG_STATE_IOERROR)
		goto out_error;

	while (be64_to_cpu(iclog->ic_header.h_lsn) != lsn) {
		iclog = iclog->ic_next;
		if (iclog == log->l_iclog)
			goto out_unlock;
	}

	if (iclog->ic_state == XLOG_STATE_ACTIVE) {
		/*
		 * We sleep here if we haven't already slept (e.g. this is the
		 * first time we've looked at the correct iclog buf) and the
		 * buffer before us is going to be sync'ed.  The reason for this
		 * is that if we are doing sync transactions here, by waiting
		 * for the previous I/O to complete, we can allow a few more
		 * transactions into this iclog before we close it down.
		 *
		 * Otherwise, we mark the buffer WANT_SYNC, and bump up the
		 * refcnt so we can release the log (which drops the ref count).
		 * The state switch keeps new transaction commits from using
		 * this buffer.  When the current commits finish writing into
		 * the buffer, the refcount will drop to zero and the buffer
		 * will go out then.
		 */
		if (!already_slept &&
		    (iclog->ic_prev->ic_state == XLOG_STATE_WANT_SYNC ||
		     iclog->ic_prev->ic_state == XLOG_STATE_SYNCING)) {
			XFS_STATS_INC(mp, xs_log_force_sleep);

			xlog_wait(&iclog->ic_prev->ic_write_wait,
					&log->l_icloglock);
			return -EAGAIN;
		}
		atomic_inc(&iclog->ic_refcnt);
		xlog_state_switch_iclogs(log, iclog, 0);
		if (xlog_state_release_iclog(log, iclog))
			goto out_error;
		if (log_flushed)
			*log_flushed = 1;
	}

	if (flags & XFS_LOG_SYNC)
		return xlog_wait_on_iclog(iclog);
out_unlock:
	spin_unlock(&log->l_icloglock);
	return 0;
out_error:
	spin_unlock(&log->l_icloglock);
	return -EIO;
}

/*
 * Force the in-core log to disk for a specific LSN.
 *
 * Find in-core log with lsn.
 *	If it is in the DIRTY state, just return.
 *	If it is in the ACTIVE state, move the in-core log into the WANT_SYNC
 *		state and go to sleep or return.
 *	If it is in any other state, go to sleep or return.
 *
 * Synchronous forces are implemented with a wait queue.  All callers trying
 * to force a given lsn to disk must wait on the queue attached to the
 * specific in-core log.  When given in-core log finally completes its write
 * to disk, that thread will wake up all threads waiting on the queue.
 */
int
xfs_log_force_lsn(
	struct xfs_mount	*mp,
	xfs_lsn_t		lsn,
	uint			flags,
	int			*log_flushed)
{
	int			ret;
	ASSERT(lsn != 0);

	XFS_STATS_INC(mp, xs_log_force);
	trace_xfs_log_force(mp, lsn, _RET_IP_);

	lsn = xlog_cil_force_lsn(mp->m_log, lsn);
	if (lsn == NULLCOMMITLSN)
		return 0;

	ret = __xfs_log_force_lsn(mp, lsn, flags, log_flushed, false);
	if (ret == -EAGAIN)
		ret = __xfs_log_force_lsn(mp, lsn, flags, log_flushed, true);
	return ret;
}

/*
 * Free a used ticket when its refcount falls to zero.
 */
void
xfs_log_ticket_put(
	xlog_ticket_t	*ticket)
{
	ASSERT(atomic_read(&ticket->t_ref) > 0);
	if (atomic_dec_and_test(&ticket->t_ref))
		kmem_cache_free(xfs_log_ticket_zone, ticket);
}

xlog_ticket_t *
xfs_log_ticket_get(
	xlog_ticket_t	*ticket)
{
	ASSERT(atomic_read(&ticket->t_ref) > 0);
	atomic_inc(&ticket->t_ref);
	return ticket;
}

/*
 * Figure out the total log space unit (in bytes) that would be
 * required for a log ticket.
 */
int
xfs_log_calc_unit_res(
	struct xfs_mount	*mp,
	int			unit_bytes)
{
	struct xlog		*log = mp->m_log;
	int			iclog_space;
	uint			num_headers;

	/*
	 * Permanent reservations have up to 'cnt'-1 active log operations
	 * in the log.  A unit in this case is the amount of space for one
	 * of these log operations.  Normal reservations have a cnt of 1
	 * and their unit amount is the total amount of space required.
	 *
	 * The following lines of code account for non-transaction data
	 * which occupy space in the on-disk log.
	 *
	 * Normal form of a transaction is:
	 * <oph><trans-hdr><start-oph><reg1-oph><reg1><reg2-oph>...<commit-oph>
	 * and then there are LR hdrs, split-recs and roundoff at end of syncs.
	 *
	 * We need to account for all the leadup data and trailer data
	 * around the transaction data.
	 * And then we need to account for the worst case in terms of using
	 * more space.
	 * The worst case will happen if:
	 * - the placement of the transaction happens to be such that the
	 *   roundoff is at its maximum
	 * - the transaction data is synced before the commit record is synced
	 *   i.e. <transaction-data><roundoff> | <commit-rec><roundoff>
	 *   Therefore the commit record is in its own Log Record.
	 *   This can happen as the commit record is called with its
	 *   own region to xlog_write().
	 *   This then means that in the worst case, roundoff can happen for
	 *   the commit-rec as well.
	 *   The commit-rec is smaller than padding in this scenario and so it is
	 *   not added separately.
	 */

	/* for trans header */
	unit_bytes += sizeof(xlog_op_header_t);
	unit_bytes += sizeof(xfs_trans_header_t);

	/* for start-rec */
	unit_bytes += sizeof(xlog_op_header_t);

	/*
	 * for LR headers - the space for data in an iclog is the size minus
	 * the space used for the headers. If we use the iclog size, then we
	 * undercalculate the number of headers required.
	 *
	 * Furthermore - the addition of op headers for split-recs might
	 * increase the space required enough to require more log and op
	 * headers, so take that into account too.
	 *
	 * IMPORTANT: This reservation makes the assumption that if this
	 * transaction is the first in an iclog and hence has the LR headers
	 * accounted to it, then the remaining space in the iclog is
	 * exclusively for this transaction.  i.e. if the transaction is larger
	 * than the iclog, it will be the only thing in that iclog.
	 * Fundamentally, this means we must pass the entire log vector to
	 * xlog_write to guarantee this.
	 */
	iclog_space = log->l_iclog_size - log->l_iclog_hsize;
	num_headers = howmany(unit_bytes, iclog_space);

	/* for split-recs - ophdrs added when data split over LRs */
	unit_bytes += sizeof(xlog_op_header_t) * num_headers;

	/* add extra header reservations if we overrun */
	while (!num_headers ||
	       howmany(unit_bytes, iclog_space) > num_headers) {
		unit_bytes += sizeof(xlog_op_header_t);
		num_headers++;
	}
	unit_bytes += log->l_iclog_hsize * num_headers;

	/* for commit-rec LR header - note: padding will subsume the ophdr */
	unit_bytes += log->l_iclog_hsize;

	/* for roundoff padding for transaction data and one for commit record */
	if (xfs_sb_version_haslogv2(&mp->m_sb) && mp->m_sb.sb_logsunit > 1) {
		/* log su roundoff */
		unit_bytes += 2 * mp->m_sb.sb_logsunit;
	} else {
		/* BB roundoff */
		unit_bytes += 2 * BBSIZE;
        }

	return unit_bytes;
}

/*
 * Allocate and initialise a new log ticket.
 */
struct xlog_ticket *
xlog_ticket_alloc(
	struct xlog		*log,
	int			unit_bytes,
	int			cnt,
	char			client,
	bool			permanent)
{
	struct xlog_ticket	*tic;
	int			unit_res;

	tic = kmem_cache_zalloc(xfs_log_ticket_zone, GFP_NOFS | __GFP_NOFAIL);

	unit_res = xfs_log_calc_unit_res(log->l_mp, unit_bytes);

	atomic_set(&tic->t_ref, 1);
	tic->t_task		= current;
	INIT_LIST_HEAD(&tic->t_queue);
	tic->t_unit_res		= unit_res;
	tic->t_curr_res		= unit_res;
	tic->t_cnt		= cnt;
	tic->t_ocnt		= cnt;
	tic->t_tid		= prandom_u32();
	tic->t_clientid		= client;
	if (permanent)
		tic->t_flags |= XLOG_TIC_PERM_RESERV;

	xlog_tic_reset_res(tic);

	return tic;
}

#if defined(DEBUG)
/*
 * Make sure that the destination ptr is within the valid data region of
 * one of the iclogs.  This uses backup pointers stored in a different
 * part of the log in case we trash the log structure.
 */
STATIC void
xlog_verify_dest_ptr(
	struct xlog	*log,
	void		*ptr)
{
	int i;
	int good_ptr = 0;

	for (i = 0; i < log->l_iclog_bufs; i++) {
		if (ptr >= log->l_iclog_bak[i] &&
		    ptr <= log->l_iclog_bak[i] + log->l_iclog_size)
			good_ptr++;
	}

	if (!good_ptr)
		xfs_emerg(log->l_mp, "%s: invalid ptr", __func__);
}

/*
 * Check to make sure the grant write head didn't just over lap the tail.  If
 * the cycles are the same, we can't be overlapping.  Otherwise, make sure that
 * the cycles differ by exactly one and check the byte count.
 *
 * This check is run unlocked, so can give false positives. Rather than assert
 * on failures, use a warn-once flag and a panic tag to allow the admin to
 * determine if they want to panic the machine when such an error occurs. For
 * debug kernels this will have the same effect as using an assert but, unlinke
 * an assert, it can be turned off at runtime.
 */
STATIC void
xlog_verify_grant_tail(
	struct xlog	*log)
{
	int		tail_cycle, tail_blocks;
	int		cycle, space;

	xlog_crack_grant_head(&log->l_write_head.grant, &cycle, &space);
	xlog_crack_atomic_lsn(&log->l_tail_lsn, &tail_cycle, &tail_blocks);
	if (tail_cycle != cycle) {
		if (cycle - 1 != tail_cycle &&
		    !(log->l_flags & XLOG_TAIL_WARN)) {
			xfs_alert_tag(log->l_mp, XFS_PTAG_LOGRES,
				"%s: cycle - 1 != tail_cycle", __func__);
			log->l_flags |= XLOG_TAIL_WARN;
		}

		if (space > BBTOB(tail_blocks) &&
		    !(log->l_flags & XLOG_TAIL_WARN)) {
			xfs_alert_tag(log->l_mp, XFS_PTAG_LOGRES,
				"%s: space > BBTOB(tail_blocks)", __func__);
			log->l_flags |= XLOG_TAIL_WARN;
		}
	}
}

/* check if it will fit */
STATIC void
xlog_verify_tail_lsn(
	struct xlog		*log,
	struct xlog_in_core	*iclog,
	xfs_lsn_t		tail_lsn)
{
    int blocks;

    if (CYCLE_LSN(tail_lsn) == log->l_prev_cycle) {
	blocks =
	    log->l_logBBsize - (log->l_prev_block - BLOCK_LSN(tail_lsn));
	if (blocks < BTOBB(iclog->ic_offset)+BTOBB(log->l_iclog_hsize))
		xfs_emerg(log->l_mp, "%s: ran out of log space", __func__);
    } else {
	ASSERT(CYCLE_LSN(tail_lsn)+1 == log->l_prev_cycle);

	if (BLOCK_LSN(tail_lsn) == log->l_prev_block)
		xfs_emerg(log->l_mp, "%s: tail wrapped", __func__);

	blocks = BLOCK_LSN(tail_lsn) - log->l_prev_block;
	if (blocks < BTOBB(iclog->ic_offset) + 1)
		xfs_emerg(log->l_mp, "%s: ran out of log space", __func__);
    }
}

/*
 * Perform a number of checks on the iclog before writing to disk.
 *
 * 1. Make sure the iclogs are still circular
 * 2. Make sure we have a good magic number
 * 3. Make sure we don't have magic numbers in the data
 * 4. Check fields of each log operation header for:
 *	A. Valid client identifier
 *	B. tid ptr value falls in valid ptr space (user space code)
 *	C. Length in log record header is correct according to the
 *		individual operation headers within record.
 * 5. When a bwrite will occur within 5 blocks of the front of the physical
 *	log, check the preceding blocks of the physical log to make sure all
 *	the cycle numbers agree with the current cycle number.
 */
STATIC void
xlog_verify_iclog(
	struct xlog		*log,
	struct xlog_in_core	*iclog,
	int			count)
{
	xlog_op_header_t	*ophead;
	xlog_in_core_t		*icptr;
	xlog_in_core_2_t	*xhdr;
	void			*base_ptr, *ptr, *p;
	ptrdiff_t		field_offset;
	uint8_t			clientid;
	int			len, i, j, k, op_len;
	int			idx;

	/* check validity of iclog pointers */
	spin_lock(&log->l_icloglock);
	icptr = log->l_iclog;
	for (i = 0; i < log->l_iclog_bufs; i++, icptr = icptr->ic_next)
		ASSERT(icptr);

	if (icptr != log->l_iclog)
		xfs_emerg(log->l_mp, "%s: corrupt iclog ring", __func__);
	spin_unlock(&log->l_icloglock);

	/* check log magic numbers */
	if (iclog->ic_header.h_magicno != cpu_to_be32(XLOG_HEADER_MAGIC_NUM))
		xfs_emerg(log->l_mp, "%s: invalid magic num", __func__);

	base_ptr = ptr = &iclog->ic_header;
	p = &iclog->ic_header;
	for (ptr += BBSIZE; ptr < base_ptr + count; ptr += BBSIZE) {
		if (*(__be32 *)ptr == cpu_to_be32(XLOG_HEADER_MAGIC_NUM))
			xfs_emerg(log->l_mp, "%s: unexpected magic num",
				__func__);
	}

	/* check fields */
	len = be32_to_cpu(iclog->ic_header.h_num_logops);
	base_ptr = ptr = iclog->ic_datap;
	ophead = ptr;
	xhdr = iclog->ic_data;
	for (i = 0; i < len; i++) {
		ophead = ptr;

		/* clientid is only 1 byte */
		p = &ophead->oh_clientid;
		field_offset = p - base_ptr;
		if (field_offset & 0x1ff) {
			clientid = ophead->oh_clientid;
		} else {
			idx = BTOBBT((char *)&ophead->oh_clientid - iclog->ic_datap);
			if (idx >= (XLOG_HEADER_CYCLE_SIZE / BBSIZE)) {
				j = idx / (XLOG_HEADER_CYCLE_SIZE / BBSIZE);
				k = idx % (XLOG_HEADER_CYCLE_SIZE / BBSIZE);
				clientid = xlog_get_client_id(
					xhdr[j].hic_xheader.xh_cycle_data[k]);
			} else {
				clientid = xlog_get_client_id(
					iclog->ic_header.h_cycle_data[idx]);
			}
		}
		if (clientid != XFS_TRANSACTION && clientid != XFS_LOG)
			xfs_warn(log->l_mp,
				"%s: invalid clientid %d op "PTR_FMT" offset 0x%lx",
				__func__, clientid, ophead,
				(unsigned long)field_offset);

		/* check length */
		p = &ophead->oh_len;
		field_offset = p - base_ptr;
		if (field_offset & 0x1ff) {
			op_len = be32_to_cpu(ophead->oh_len);
		} else {
			idx = BTOBBT((uintptr_t)&ophead->oh_len -
				    (uintptr_t)iclog->ic_datap);
			if (idx >= (XLOG_HEADER_CYCLE_SIZE / BBSIZE)) {
				j = idx / (XLOG_HEADER_CYCLE_SIZE / BBSIZE);
				k = idx % (XLOG_HEADER_CYCLE_SIZE / BBSIZE);
				op_len = be32_to_cpu(xhdr[j].hic_xheader.xh_cycle_data[k]);
			} else {
				op_len = be32_to_cpu(iclog->ic_header.h_cycle_data[idx]);
			}
		}
		ptr += sizeof(xlog_op_header_t) + op_len;
	}
}
#endif

/*
 * Mark all iclogs IOERROR. l_icloglock is held by the caller.
 */
STATIC int
xlog_state_ioerror(
	struct xlog	*log)
{
	xlog_in_core_t	*iclog, *ic;

	iclog = log->l_iclog;
	if (iclog->ic_state != XLOG_STATE_IOERROR) {
		/*
		 * Mark all the incore logs IOERROR.
		 * From now on, no log flushes will result.
		 */
		ic = iclog;
		do {
			ic->ic_state = XLOG_STATE_IOERROR;
			ic = ic->ic_next;
		} while (ic != iclog);
		return 0;
	}
	/*
	 * Return non-zero, if state transition has already happened.
	 */
	return 1;
}

/*
 * This is called from xfs_force_shutdown, when we're forcibly
 * shutting down the filesystem, typically because of an IO error.
 * Our main objectives here are to make sure that:
 *	a. if !logerror, flush the logs to disk. Anything modified
 *	   after this is ignored.
 *	b. the filesystem gets marked 'SHUTDOWN' for all interested
 *	   parties to find out, 'atomically'.
 *	c. those who're sleeping on log reservations, pinned objects and
 *	    other resources get woken up, and be told the bad news.
 *	d. nothing new gets queued up after (b) and (c) are done.
 *
 * Note: for the !logerror case we need to flush the regions held in memory out
 * to disk first. This needs to be done before the log is marked as shutdown,
 * otherwise the iclog writes will fail.
 */
int
xfs_log_force_umount(
	struct xfs_mount	*mp,
	int			logerror)
{
	struct xlog	*log;
	int		retval;

	log = mp->m_log;

	/*
	 * If this happens during log recovery, don't worry about
	 * locking; the log isn't open for business yet.
	 */
	if (!log ||
	    log->l_flags & XLOG_ACTIVE_RECOVERY) {
		mp->m_flags |= XFS_MOUNT_FS_SHUTDOWN;
		if (mp->m_sb_bp)
			mp->m_sb_bp->b_flags |= XBF_DONE;
		return 0;
	}

	/*
	 * Somebody could've already done the hard work for us.
	 * No need to get locks for this.
	 */
	if (logerror && log->l_iclog->ic_state == XLOG_STATE_IOERROR) {
		ASSERT(XLOG_FORCED_SHUTDOWN(log));
		return 1;
	}

	/*
	 * Flush all the completed transactions to disk before marking the log
	 * being shut down. We need to do it in this order to ensure that
	 * completed operations are safely on disk before we shut down, and that
	 * we don't have to issue any buffer IO after the shutdown flags are set
	 * to guarantee this.
	 */
	if (!logerror)
		xfs_log_force(mp, XFS_LOG_SYNC);

	/*
	 * mark the filesystem and the as in a shutdown state and wake
	 * everybody up to tell them the bad news.
	 */
	spin_lock(&log->l_icloglock);
	mp->m_flags |= XFS_MOUNT_FS_SHUTDOWN;
	if (mp->m_sb_bp)
		mp->m_sb_bp->b_flags |= XBF_DONE;

	/*
	 * Mark the log and the iclogs with IO error flags to prevent any
	 * further log IO from being issued or completed.
	 */
	log->l_flags |= XLOG_IO_ERROR;
	retval = xlog_state_ioerror(log);
	spin_unlock(&log->l_icloglock);

	/*
	 * We don't want anybody waiting for log reservations after this. That
	 * means we have to wake up everybody queued up on reserveq as well as
	 * writeq.  In addition, we make sure in xlog_{re}grant_log_space that
	 * we don't enqueue anything once the SHUTDOWN flag is set, and this
	 * action is protected by the grant locks.
	 */
	xlog_grant_head_wake_all(&log->l_reserve_head);
	xlog_grant_head_wake_all(&log->l_write_head);

	/*
	 * Wake up everybody waiting on xfs_log_force. Wake the CIL push first
	 * as if the log writes were completed. The abort handling in the log
	 * item committed callback functions will do this again under lock to
	 * avoid races.
	 */
	spin_lock(&log->l_cilp->xc_push_lock);
	wake_up_all(&log->l_cilp->xc_commit_wait);
	spin_unlock(&log->l_cilp->xc_push_lock);
	xlog_state_do_callback(log);

	/* return non-zero if log IOERROR transition had already happened */
	return retval;
}

STATIC int
xlog_iclogs_empty(
	struct xlog	*log)
{
	xlog_in_core_t	*iclog;

	iclog = log->l_iclog;
	do {
		/* endianness does not matter here, zero is zero in
		 * any language.
		 */
		if (iclog->ic_header.h_num_logops)
			return 0;
		iclog = iclog->ic_next;
	} while (iclog != log->l_iclog);
	return 1;
}

/*
 * Verify that an LSN stamped into a piece of metadata is valid. This is
 * intended for use in read verifiers on v5 superblocks.
 */
bool
xfs_log_check_lsn(
	struct xfs_mount	*mp,
	xfs_lsn_t		lsn)
{
	struct xlog		*log = mp->m_log;
	bool			valid;

	/*
	 * norecovery mode skips mount-time log processing and unconditionally
	 * resets the in-core LSN. We can't validate in this mode, but
	 * modifications are not allowed anyways so just return true.
	 */
	if (mp->m_flags & XFS_MOUNT_NORECOVERY)
		return true;

	/*
	 * Some metadata LSNs are initialized to NULL (e.g., the agfl). This is
	 * handled by recovery and thus safe to ignore here.
	 */
	if (lsn == NULLCOMMITLSN)
		return true;

	valid = xlog_valid_lsn(mp->m_log, lsn);

	/* warn the user about what's gone wrong before verifier failure */
	if (!valid) {
		spin_lock(&log->l_icloglock);
		xfs_warn(mp,
"Corruption warning: Metadata has LSN (%d:%d) ahead of current LSN (%d:%d). "
"Please unmount and run xfs_repair (>= v4.3) to resolve.",
			 CYCLE_LSN(lsn), BLOCK_LSN(lsn),
			 log->l_curr_cycle, log->l_curr_block);
		spin_unlock(&log->l_icloglock);
	}

	return valid;
}

bool
xfs_log_in_recovery(
	struct xfs_mount	*mp)
{
	struct xlog		*log = mp->m_log;

	return log->l_flags & XLOG_ACTIVE_RECOVERY;
}