fix_node.c 77.4 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
/*
 * Copyright 2000 by Hans Reiser, licensing governed by reiserfs/README
 */

/**
 ** old_item_num
 ** old_entry_num
 ** set_entry_sizes
 ** create_virtual_node
 ** check_left
 ** check_right
 ** directory_part_size
 ** get_num_ver
 ** set_parameters
 ** is_leaf_removable
 ** are_leaves_removable
 ** get_empty_nodes
 ** get_lfree
 ** get_rfree
 ** is_left_neighbor_in_cache
 ** decrement_key
 ** get_far_parent
 ** get_parents
 ** can_node_be_removed
 ** ip_check_balance
 ** dc_check_balance_internal
 ** dc_check_balance_leaf
 ** dc_check_balance
 ** check_balance
 ** get_direct_parent
 ** get_neighbors
 ** fix_nodes
 **
 **
 **/

#include <linux/time.h>
#include <linux/slab.h>
#include <linux/string.h>
#include "reiserfs.h"
#include <linux/buffer_head.h>

/* To make any changes in the tree we find a node, that contains item
   to be changed/deleted or position in the node we insert a new item
   to. We call this node S. To do balancing we need to decide what we
   will shift to left/right neighbor, or to a new node, where new item
   will be etc. To make this analysis simpler we build virtual
   node. Virtual node is an array of items, that will replace items of
   node S. (For instance if we are going to delete an item, virtual
   node does not contain it). Virtual node keeps information about
   item sizes and types, mergeability of first and last items, sizes
   of all entries in directory item. We use this array of items when
   calculating what we can shift to neighbors and how many nodes we
   have to have if we do not any shiftings, if we shift to left/right
   neighbor or to both. */

/* taking item number in virtual node, returns number of item, that it has in source buffer */
static inline int old_item_num(int new_num, int affected_item_num, int mode)
{
	if (mode == M_PASTE || mode == M_CUT || new_num < affected_item_num)
		return new_num;

	if (mode == M_INSERT) {

		RFALSE(new_num == 0,
		       "vs-8005: for INSERT mode and item number of inserted item");

		return new_num - 1;
	}

	RFALSE(mode != M_DELETE,
	       "vs-8010: old_item_num: mode must be M_DELETE (mode = \'%c\'",
	       mode);
	/* delete mode */
	return new_num + 1;
}

static void create_virtual_node(struct tree_balance *tb, int h)
{
	struct item_head *ih;
	struct virtual_node *vn = tb->tb_vn;
	int new_num;
	struct buffer_head *Sh;	/* this comes from tb->S[h] */

	Sh = PATH_H_PBUFFER(tb->tb_path, h);

	/* size of changed node */
	vn->vn_size =
	    MAX_CHILD_SIZE(Sh) - B_FREE_SPACE(Sh) + tb->insert_size[h];

	/* for internal nodes array if virtual items is not created */
	if (h) {
		vn->vn_nr_item = (vn->vn_size - DC_SIZE) / (DC_SIZE + KEY_SIZE);
		return;
	}

	/* number of items in virtual node  */
	vn->vn_nr_item =
	    B_NR_ITEMS(Sh) + ((vn->vn_mode == M_INSERT) ? 1 : 0) -
	    ((vn->vn_mode == M_DELETE) ? 1 : 0);

	/* first virtual item */
	vn->vn_vi = (struct virtual_item *)(tb->tb_vn + 1);
	memset(vn->vn_vi, 0, vn->vn_nr_item * sizeof(struct virtual_item));
	vn->vn_free_ptr += vn->vn_nr_item * sizeof(struct virtual_item);

	/* first item in the node */
	ih = B_N_PITEM_HEAD(Sh, 0);

	/* define the mergeability for 0-th item (if it is not being deleted) */
	if (op_is_left_mergeable(&(ih->ih_key), Sh->b_size)
	    && (vn->vn_mode != M_DELETE || vn->vn_affected_item_num))
		vn->vn_vi[0].vi_type |= VI_TYPE_LEFT_MERGEABLE;

	/* go through all items those remain in the virtual node (except for the new (inserted) one) */
	for (new_num = 0; new_num < vn->vn_nr_item; new_num++) {
		int j;
		struct virtual_item *vi = vn->vn_vi + new_num;
		int is_affected =
		    ((new_num != vn->vn_affected_item_num) ? 0 : 1);

		if (is_affected && vn->vn_mode == M_INSERT)
			continue;

		/* get item number in source node */
		j = old_item_num(new_num, vn->vn_affected_item_num,
				 vn->vn_mode);

		vi->vi_item_len += ih_item_len(ih + j) + IH_SIZE;
		vi->vi_ih = ih + j;
		vi->vi_item = B_I_PITEM(Sh, ih + j);
		vi->vi_uarea = vn->vn_free_ptr;

		// FIXME: there is no check, that item operation did not
		// consume too much memory
		vn->vn_free_ptr +=
		    op_create_vi(vn, vi, is_affected, tb->insert_size[0]);
		if (tb->vn_buf + tb->vn_buf_size < vn->vn_free_ptr)
			reiserfs_panic(tb->tb_sb, "vs-8030",
				       "virtual node space consumed");

		if (!is_affected)
			/* this is not being changed */
			continue;

		if (vn->vn_mode == M_PASTE || vn->vn_mode == M_CUT) {
			vn->vn_vi[new_num].vi_item_len += tb->insert_size[0];
			vi->vi_new_data = vn->vn_data;	// pointer to data which is going to be pasted
		}
	}

	/* virtual inserted item is not defined yet */
	if (vn->vn_mode == M_INSERT) {
		struct virtual_item *vi = vn->vn_vi + vn->vn_affected_item_num;

		RFALSE(vn->vn_ins_ih == NULL,
		       "vs-8040: item header of inserted item is not specified");
		vi->vi_item_len = tb->insert_size[0];
		vi->vi_ih = vn->vn_ins_ih;
		vi->vi_item = vn->vn_data;
		vi->vi_uarea = vn->vn_free_ptr;

		op_create_vi(vn, vi, 0 /*not pasted or cut */ ,
			     tb->insert_size[0]);
	}

	/* set right merge flag we take right delimiting key and check whether it is a mergeable item */
	if (tb->CFR[0]) {
		struct reiserfs_key *key;

		key = B_N_PDELIM_KEY(tb->CFR[0], tb->rkey[0]);
		if (op_is_left_mergeable(key, Sh->b_size)
		    && (vn->vn_mode != M_DELETE
			|| vn->vn_affected_item_num != B_NR_ITEMS(Sh) - 1))
			vn->vn_vi[vn->vn_nr_item - 1].vi_type |=
			    VI_TYPE_RIGHT_MERGEABLE;

#ifdef CONFIG_REISERFS_CHECK
		if (op_is_left_mergeable(key, Sh->b_size) &&
		    !(vn->vn_mode != M_DELETE
		      || vn->vn_affected_item_num != B_NR_ITEMS(Sh) - 1)) {
			/* we delete last item and it could be merged with right neighbor's first item */
			if (!
			    (B_NR_ITEMS(Sh) == 1
			     && is_direntry_le_ih(B_N_PITEM_HEAD(Sh, 0))
			     && I_ENTRY_COUNT(B_N_PITEM_HEAD(Sh, 0)) == 1)) {
				/* node contains more than 1 item, or item is not directory item, or this item contains more than 1 entry */
				print_block(Sh, 0, -1, -1);
				reiserfs_panic(tb->tb_sb, "vs-8045",
					       "rdkey %k, affected item==%d "
					       "(mode==%c) Must be %c",
					       key, vn->vn_affected_item_num,
					       vn->vn_mode, M_DELETE);
			}
		}
#endif

	}
}

/* using virtual node check, how many items can be shifted to left
   neighbor */
static void check_left(struct tree_balance *tb, int h, int cur_free)
{
	int i;
	struct virtual_node *vn = tb->tb_vn;
	struct virtual_item *vi;
	int d_size, ih_size;

	RFALSE(cur_free < 0, "vs-8050: cur_free (%d) < 0", cur_free);

	/* internal level */
	if (h > 0) {
		tb->lnum[h] = cur_free / (DC_SIZE + KEY_SIZE);
		return;
	}

	/* leaf level */

	if (!cur_free || !vn->vn_nr_item) {
		/* no free space or nothing to move */
		tb->lnum[h] = 0;
		tb->lbytes = -1;
		return;
	}

	RFALSE(!PATH_H_PPARENT(tb->tb_path, 0),
	       "vs-8055: parent does not exist or invalid");

	vi = vn->vn_vi;
	if ((unsigned int)cur_free >=
	    (vn->vn_size -
	     ((vi->vi_type & VI_TYPE_LEFT_MERGEABLE) ? IH_SIZE : 0))) {
		/* all contents of S[0] fits into L[0] */

		RFALSE(vn->vn_mode == M_INSERT || vn->vn_mode == M_PASTE,
		       "vs-8055: invalid mode or balance condition failed");

		tb->lnum[0] = vn->vn_nr_item;
		tb->lbytes = -1;
		return;
	}

	d_size = 0, ih_size = IH_SIZE;

	/* first item may be merge with last item in left neighbor */
	if (vi->vi_type & VI_TYPE_LEFT_MERGEABLE)
		d_size = -((int)IH_SIZE), ih_size = 0;

	tb->lnum[0] = 0;
	for (i = 0; i < vn->vn_nr_item;
	     i++, ih_size = IH_SIZE, d_size = 0, vi++) {
		d_size += vi->vi_item_len;
		if (cur_free >= d_size) {
			/* the item can be shifted entirely */
			cur_free -= d_size;
			tb->lnum[0]++;
			continue;
		}

		/* the item cannot be shifted entirely, try to split it */
		/* check whether L[0] can hold ih and at least one byte of the item body */
		if (cur_free <= ih_size) {
			/* cannot shift even a part of the current item */
			tb->lbytes = -1;
			return;
		}
		cur_free -= ih_size;

		tb->lbytes = op_check_left(vi, cur_free, 0, 0);
		if (tb->lbytes != -1)
			/* count partially shifted item */
			tb->lnum[0]++;

		break;
	}

	return;
}

/* using virtual node check, how many items can be shifted to right
   neighbor */
static void check_right(struct tree_balance *tb, int h, int cur_free)
{
	int i;
	struct virtual_node *vn = tb->tb_vn;
	struct virtual_item *vi;
	int d_size, ih_size;

	RFALSE(cur_free < 0, "vs-8070: cur_free < 0");

	/* internal level */
	if (h > 0) {
		tb->rnum[h] = cur_free / (DC_SIZE + KEY_SIZE);
		return;
	}

	/* leaf level */

	if (!cur_free || !vn->vn_nr_item) {
		/* no free space  */
		tb->rnum[h] = 0;
		tb->rbytes = -1;
		return;
	}

	RFALSE(!PATH_H_PPARENT(tb->tb_path, 0),
	       "vs-8075: parent does not exist or invalid");

	vi = vn->vn_vi + vn->vn_nr_item - 1;
	if ((unsigned int)cur_free >=
	    (vn->vn_size -
	     ((vi->vi_type & VI_TYPE_RIGHT_MERGEABLE) ? IH_SIZE : 0))) {
		/* all contents of S[0] fits into R[0] */

		RFALSE(vn->vn_mode == M_INSERT || vn->vn_mode == M_PASTE,
		       "vs-8080: invalid mode or balance condition failed");

		tb->rnum[h] = vn->vn_nr_item;
		tb->rbytes = -1;
		return;
	}

	d_size = 0, ih_size = IH_SIZE;

	/* last item may be merge with first item in right neighbor */
	if (vi->vi_type & VI_TYPE_RIGHT_MERGEABLE)
		d_size = -(int)IH_SIZE, ih_size = 0;

	tb->rnum[0] = 0;
	for (i = vn->vn_nr_item - 1; i >= 0;
	     i--, d_size = 0, ih_size = IH_SIZE, vi--) {
		d_size += vi->vi_item_len;
		if (cur_free >= d_size) {
			/* the item can be shifted entirely */
			cur_free -= d_size;
			tb->rnum[0]++;
			continue;
		}

		/* check whether R[0] can hold ih and at least one byte of the item body */
		if (cur_free <= ih_size) {	/* cannot shift even a part of the current item */
			tb->rbytes = -1;
			return;
		}

		/* R[0] can hold the header of the item and at least one byte of its body */
		cur_free -= ih_size;	/* cur_free is still > 0 */

		tb->rbytes = op_check_right(vi, cur_free);
		if (tb->rbytes != -1)
			/* count partially shifted item */
			tb->rnum[0]++;

		break;
	}

	return;
}

/*
 * from - number of items, which are shifted to left neighbor entirely
 * to - number of item, which are shifted to right neighbor entirely
 * from_bytes - number of bytes of boundary item (or directory entries) which are shifted to left neighbor
 * to_bytes - number of bytes of boundary item (or directory entries) which are shifted to right neighbor */
static int get_num_ver(int mode, struct tree_balance *tb, int h,
		       int from, int from_bytes,
		       int to, int to_bytes, short *snum012, int flow)
{
	int i;
	int cur_free;
	//    int bytes;
	int units;
	struct virtual_node *vn = tb->tb_vn;
	//    struct virtual_item * vi;

	int total_node_size, max_node_size, current_item_size;
	int needed_nodes;
	int start_item,		/* position of item we start filling node from */
	 end_item,		/* position of item we finish filling node by */
	 start_bytes,		/* number of first bytes (entries for directory) of start_item-th item
				   we do not include into node that is being filled */
	 end_bytes;		/* number of last bytes (entries for directory) of end_item-th item
				   we do node include into node that is being filled */
	int split_item_positions[2];	/* these are positions in virtual item of
					   items, that are split between S[0] and
					   S1new and S1new and S2new */

	split_item_positions[0] = -1;
	split_item_positions[1] = -1;

	/* We only create additional nodes if we are in insert or paste mode
	   or we are in replace mode at the internal level. If h is 0 and
	   the mode is M_REPLACE then in fix_nodes we change the mode to
	   paste or insert before we get here in the code.  */
	RFALSE(tb->insert_size[h] < 0 || (mode != M_INSERT && mode != M_PASTE),
	       "vs-8100: insert_size < 0 in overflow");

	max_node_size = MAX_CHILD_SIZE(PATH_H_PBUFFER(tb->tb_path, h));

	/* snum012 [0-2] - number of items, that lay
	   to S[0], first new node and second new node */
	snum012[3] = -1;	/* s1bytes */
	snum012[4] = -1;	/* s2bytes */

	/* internal level */
	if (h > 0) {
		i = ((to - from) * (KEY_SIZE + DC_SIZE) + DC_SIZE);
		if (i == max_node_size)
			return 1;
		return (i / max_node_size + 1);
	}

	/* leaf level */
	needed_nodes = 1;
	total_node_size = 0;
	cur_free = max_node_size;

	// start from 'from'-th item
	start_item = from;
	// skip its first 'start_bytes' units
	start_bytes = ((from_bytes != -1) ? from_bytes : 0);

	// last included item is the 'end_item'-th one
	end_item = vn->vn_nr_item - to - 1;
	// do not count last 'end_bytes' units of 'end_item'-th item
	end_bytes = (to_bytes != -1) ? to_bytes : 0;

	/* go through all item beginning from the start_item-th item and ending by
	   the end_item-th item. Do not count first 'start_bytes' units of
	   'start_item'-th item and last 'end_bytes' of 'end_item'-th item */

	for (i = start_item; i <= end_item; i++) {
		struct virtual_item *vi = vn->vn_vi + i;
		int skip_from_end = ((i == end_item) ? end_bytes : 0);

		RFALSE(needed_nodes > 3, "vs-8105: too many nodes are needed");

		/* get size of current item */
		current_item_size = vi->vi_item_len;

		/* do not take in calculation head part (from_bytes) of from-th item */
		current_item_size -=
		    op_part_size(vi, 0 /*from start */ , start_bytes);

		/* do not take in calculation tail part of last item */
		current_item_size -=
		    op_part_size(vi, 1 /*from end */ , skip_from_end);

		/* if item fits into current node entierly */
		if (total_node_size + current_item_size <= max_node_size) {
			snum012[needed_nodes - 1]++;
			total_node_size += current_item_size;
			start_bytes = 0;
			continue;
		}

		if (current_item_size > max_node_size) {
			/* virtual item length is longer, than max size of item in
			   a node. It is impossible for direct item */
			RFALSE(is_direct_le_ih(vi->vi_ih),
			       "vs-8110: "
			       "direct item length is %d. It can not be longer than %d",
			       current_item_size, max_node_size);
			/* we will try to split it */
			flow = 1;
		}

		if (!flow) {
			/* as we do not split items, take new node and continue */
			needed_nodes++;
			i--;
			total_node_size = 0;
			continue;
		}
		// calculate number of item units which fit into node being
		// filled
		{
			int free_space;

			free_space = max_node_size - total_node_size - IH_SIZE;
			units =
			    op_check_left(vi, free_space, start_bytes,
					  skip_from_end);
			if (units == -1) {
				/* nothing fits into current node, take new node and continue */
				needed_nodes++, i--, total_node_size = 0;
				continue;
			}
		}

		/* something fits into the current node */
		//if (snum012[3] != -1 || needed_nodes != 1)
		//  reiserfs_panic (tb->tb_sb, "vs-8115: get_num_ver: too many nodes required");
		//snum012[needed_nodes - 1 + 3] = op_unit_num (vi) - start_bytes - units;
		start_bytes += units;
		snum012[needed_nodes - 1 + 3] = units;

		if (needed_nodes > 2)
			reiserfs_warning(tb->tb_sb, "vs-8111",
					 "split_item_position is out of range");
		snum012[needed_nodes - 1]++;
		split_item_positions[needed_nodes - 1] = i;
		needed_nodes++;
		/* continue from the same item with start_bytes != -1 */
		start_item = i;
		i--;
		total_node_size = 0;
	}

	// sum012[4] (if it is not -1) contains number of units of which
	// are to be in S1new, snum012[3] - to be in S0. They are supposed
	// to be S1bytes and S2bytes correspondingly, so recalculate
	if (snum012[4] > 0) {
		int split_item_num;
		int bytes_to_r, bytes_to_l;
		int bytes_to_S1new;

		split_item_num = split_item_positions[1];
		bytes_to_l =
		    ((from == split_item_num
		      && from_bytes != -1) ? from_bytes : 0);
		bytes_to_r =
		    ((end_item == split_item_num
		      && end_bytes != -1) ? end_bytes : 0);
		bytes_to_S1new =
		    ((split_item_positions[0] ==
		      split_item_positions[1]) ? snum012[3] : 0);

		// s2bytes
		snum012[4] =
		    op_unit_num(&vn->vn_vi[split_item_num]) - snum012[4] -
		    bytes_to_r - bytes_to_l - bytes_to_S1new;

		if (vn->vn_vi[split_item_num].vi_index != TYPE_DIRENTRY &&
		    vn->vn_vi[split_item_num].vi_index != TYPE_INDIRECT)
			reiserfs_warning(tb->tb_sb, "vs-8115",
					 "not directory or indirect item");
	}

	/* now we know S2bytes, calculate S1bytes */
	if (snum012[3] > 0) {
		int split_item_num;
		int bytes_to_r, bytes_to_l;
		int bytes_to_S2new;

		split_item_num = split_item_positions[0];
		bytes_to_l =
		    ((from == split_item_num
		      && from_bytes != -1) ? from_bytes : 0);
		bytes_to_r =
		    ((end_item == split_item_num
		      && end_bytes != -1) ? end_bytes : 0);
		bytes_to_S2new =
		    ((split_item_positions[0] == split_item_positions[1]
		      && snum012[4] != -1) ? snum012[4] : 0);

		// s1bytes
		snum012[3] =
		    op_unit_num(&vn->vn_vi[split_item_num]) - snum012[3] -
		    bytes_to_r - bytes_to_l - bytes_to_S2new;
	}

	return needed_nodes;
}


/* Set parameters for balancing.
 * Performs write of results of analysis of balancing into structure tb,
 * where it will later be used by the functions that actually do the balancing.
 * Parameters:
 *	tb	tree_balance structure;
 *	h	current level of the node;
 *	lnum	number of items from S[h] that must be shifted to L[h];
 *	rnum	number of items from S[h] that must be shifted to R[h];
 *	blk_num	number of blocks that S[h] will be splitted into;
 *	s012	number of items that fall into splitted nodes.
 *	lbytes	number of bytes which flow to the left neighbor from the item that is not
 *		not shifted entirely
 *	rbytes	number of bytes which flow to the right neighbor from the item that is not
 *		not shifted entirely
 *	s1bytes	number of bytes which flow to the first  new node when S[0] splits (this number is contained in s012 array)
 */

static void set_parameters(struct tree_balance *tb, int h, int lnum,
			   int rnum, int blk_num, short *s012, int lb, int rb)
{

	tb->lnum[h] = lnum;
	tb->rnum[h] = rnum;
	tb->blknum[h] = blk_num;

	if (h == 0) {		/* only for leaf level */
		if (s012 != NULL) {
			tb->s0num = *s012++,
			    tb->s1num = *s012++, tb->s2num = *s012++;
			tb->s1bytes = *s012++;
			tb->s2bytes = *s012;
		}
		tb->lbytes = lb;
		tb->rbytes = rb;
	}
	PROC_INFO_ADD(tb->tb_sb, lnum[h], lnum);
	PROC_INFO_ADD(tb->tb_sb, rnum[h], rnum);

	PROC_INFO_ADD(tb->tb_sb, lbytes[h], lb);
	PROC_INFO_ADD(tb->tb_sb, rbytes[h], rb);
}

/* check, does node disappear if we shift tb->lnum[0] items to left
   neighbor and tb->rnum[0] to the right one. */
static int is_leaf_removable(struct tree_balance *tb)
{
	struct virtual_node *vn = tb->tb_vn;
	int to_left, to_right;
	int size;
	int remain_items;

	/* number of items, that will be shifted to left (right) neighbor
	   entirely */
	to_left = tb->lnum[0] - ((tb->lbytes != -1) ? 1 : 0);
	to_right = tb->rnum[0] - ((tb->rbytes != -1) ? 1 : 0);
	remain_items = vn->vn_nr_item;

	/* how many items remain in S[0] after shiftings to neighbors */
	remain_items -= (to_left + to_right);

	if (remain_items < 1) {
		/* all content of node can be shifted to neighbors */
		set_parameters(tb, 0, to_left, vn->vn_nr_item - to_left, 0,
			       NULL, -1, -1);
		return 1;
	}

	if (remain_items > 1 || tb->lbytes == -1 || tb->rbytes == -1)
		/* S[0] is not removable */
		return 0;

	/* check, whether we can divide 1 remaining item between neighbors */

	/* get size of remaining item (in item units) */
	size = op_unit_num(&(vn->vn_vi[to_left]));

	if (tb->lbytes + tb->rbytes >= size) {
		set_parameters(tb, 0, to_left + 1, to_right + 1, 0, NULL,
			       tb->lbytes, -1);
		return 1;
	}

	return 0;
}

/* check whether L, S, R can be joined in one node */
static int are_leaves_removable(struct tree_balance *tb, int lfree, int rfree)
{
	struct virtual_node *vn = tb->tb_vn;
	int ih_size;
	struct buffer_head *S0;

	S0 = PATH_H_PBUFFER(tb->tb_path, 0);

	ih_size = 0;
	if (vn->vn_nr_item) {
		if (vn->vn_vi[0].vi_type & VI_TYPE_LEFT_MERGEABLE)
			ih_size += IH_SIZE;

		if (vn->vn_vi[vn->vn_nr_item - 1].
		    vi_type & VI_TYPE_RIGHT_MERGEABLE)
			ih_size += IH_SIZE;
	} else {
		/* there was only one item and it will be deleted */
		struct item_head *ih;

		RFALSE(B_NR_ITEMS(S0) != 1,
		       "vs-8125: item number must be 1: it is %d",
		       B_NR_ITEMS(S0));

		ih = B_N_PITEM_HEAD(S0, 0);
		if (tb->CFR[0]
		    && !comp_short_le_keys(&(ih->ih_key),
					   B_N_PDELIM_KEY(tb->CFR[0],
							  tb->rkey[0])))
			if (is_direntry_le_ih(ih)) {
				/* Directory must be in correct state here: that is
				   somewhere at the left side should exist first directory
				   item. But the item being deleted can not be that first
				   one because its right neighbor is item of the same
				   directory. (But first item always gets deleted in last
				   turn). So, neighbors of deleted item can be merged, so
				   we can save ih_size */
				ih_size = IH_SIZE;

				/* we might check that left neighbor exists and is of the
				   same directory */
				RFALSE(le_ih_k_offset(ih) == DOT_OFFSET,
				       "vs-8130: first directory item can not be removed until directory is not empty");
			}

	}

	if (MAX_CHILD_SIZE(S0) + vn->vn_size <= rfree + lfree + ih_size) {
		set_parameters(tb, 0, -1, -1, -1, NULL, -1, -1);
		PROC_INFO_INC(tb->tb_sb, leaves_removable);
		return 1;
	}
	return 0;

}

/* when we do not split item, lnum and rnum are numbers of entire items */
#define SET_PAR_SHIFT_LEFT \
if (h)\
{\
   int to_l;\
   \
   to_l = (MAX_NR_KEY(Sh)+1 - lpar + vn->vn_nr_item + 1) / 2 -\
	      (MAX_NR_KEY(Sh) + 1 - lpar);\
	      \
	      set_parameters (tb, h, to_l, 0, lnver, NULL, -1, -1);\
}\
else \
{\
   if (lset==LEFT_SHIFT_FLOW)\
     set_parameters (tb, h, lpar, 0, lnver, snum012+lset,\
		     tb->lbytes, -1);\
   else\
     set_parameters (tb, h, lpar - (tb->lbytes!=-1), 0, lnver, snum012+lset,\
		     -1, -1);\
}

#define SET_PAR_SHIFT_RIGHT \
if (h)\
{\
   int to_r;\
   \
   to_r = (MAX_NR_KEY(Sh)+1 - rpar + vn->vn_nr_item + 1) / 2 - (MAX_NR_KEY(Sh) + 1 - rpar);\
   \
   set_parameters (tb, h, 0, to_r, rnver, NULL, -1, -1);\
}\
else \
{\
   if (rset==RIGHT_SHIFT_FLOW)\
     set_parameters (tb, h, 0, rpar, rnver, snum012+rset,\
		  -1, tb->rbytes);\
   else\
     set_parameters (tb, h, 0, rpar - (tb->rbytes!=-1), rnver, snum012+rset,\
		  -1, -1);\
}

static void free_buffers_in_tb(struct tree_balance *tb)
{
	int i;

	pathrelse(tb->tb_path);

	for (i = 0; i < MAX_HEIGHT; i++) {
		brelse(tb->L[i]);
		brelse(tb->R[i]);
		brelse(tb->FL[i]);
		brelse(tb->FR[i]);
		brelse(tb->CFL[i]);
		brelse(tb->CFR[i]);

		tb->L[i] = NULL;
		tb->R[i] = NULL;
		tb->FL[i] = NULL;
		tb->FR[i] = NULL;
		tb->CFL[i] = NULL;
		tb->CFR[i] = NULL;
	}
}

/* Get new buffers for storing new nodes that are created while balancing.
 * Returns:	SCHEDULE_OCCURRED - schedule occurred while the function worked;
 *	        CARRY_ON - schedule didn't occur while the function worked;
 *	        NO_DISK_SPACE - no disk space.
 */
/* The function is NOT SCHEDULE-SAFE! */
static int get_empty_nodes(struct tree_balance *tb, int h)
{
	struct buffer_head *new_bh,
	    *Sh = PATH_H_PBUFFER(tb->tb_path, h);
	b_blocknr_t *blocknr, blocknrs[MAX_AMOUNT_NEEDED] = { 0, };
	int counter, number_of_freeblk, amount_needed,	/* number of needed empty blocks */
	 retval = CARRY_ON;
	struct super_block *sb = tb->tb_sb;

	/* number_of_freeblk is the number of empty blocks which have been
	   acquired for use by the balancing algorithm minus the number of
	   empty blocks used in the previous levels of the analysis,
	   number_of_freeblk = tb->cur_blknum can be non-zero if a schedule occurs
	   after empty blocks are acquired, and the balancing analysis is
	   then restarted, amount_needed is the number needed by this level
	   (h) of the balancing analysis.

	   Note that for systems with many processes writing, it would be
	   more layout optimal to calculate the total number needed by all
	   levels and then to run reiserfs_new_blocks to get all of them at once.  */

	/* Initiate number_of_freeblk to the amount acquired prior to the restart of
	   the analysis or 0 if not restarted, then subtract the amount needed
	   by all of the levels of the tree below h. */
	/* blknum includes S[h], so we subtract 1 in this calculation */
	for (counter = 0, number_of_freeblk = tb->cur_blknum;
	     counter < h; counter++)
		number_of_freeblk -=
		    (tb->blknum[counter]) ? (tb->blknum[counter] -
						   1) : 0;

	/* Allocate missing empty blocks. */
	/* if Sh == 0  then we are getting a new root */
	amount_needed = (Sh) ? (tb->blknum[h] - 1) : 1;
	/*  Amount_needed = the amount that we need more than the amount that we have. */
	if (amount_needed > number_of_freeblk)
		amount_needed -= number_of_freeblk;
	else			/* If we have enough already then there is nothing to do. */
		return CARRY_ON;

	/* No need to check quota - is not allocated for blocks used for formatted nodes */
	if (reiserfs_new_form_blocknrs(tb, blocknrs,
				       amount_needed) == NO_DISK_SPACE)
		return NO_DISK_SPACE;

	/* for each blocknumber we just got, get a buffer and stick it on FEB */
	for (blocknr = blocknrs, counter = 0;
	     counter < amount_needed; blocknr++, counter++) {

		RFALSE(!*blocknr,
		       "PAP-8135: reiserfs_new_blocknrs failed when got new blocks");

		new_bh = sb_getblk(sb, *blocknr);
		RFALSE(buffer_dirty(new_bh) ||
		       buffer_journaled(new_bh) ||
		       buffer_journal_dirty(new_bh),
		       "PAP-8140: journaled or dirty buffer %b for the new block",
		       new_bh);

		/* Put empty buffers into the array. */
		RFALSE(tb->FEB[tb->cur_blknum],
		       "PAP-8141: busy slot for new buffer");

		set_buffer_journal_new(new_bh);
		tb->FEB[tb->cur_blknum++] = new_bh;
	}

	if (retval == CARRY_ON && FILESYSTEM_CHANGED_TB(tb))
		retval = REPEAT_SEARCH;

	return retval;
}

/* Get free space of the left neighbor, which is stored in the parent
 * node of the left neighbor.  */
static int get_lfree(struct tree_balance *tb, int h)
{
	struct buffer_head *l, *f;
	int order;

	if ((f = PATH_H_PPARENT(tb->tb_path, h)) == NULL ||
	    (l = tb->FL[h]) == NULL)
		return 0;

	if (f == l)
		order = PATH_H_B_ITEM_ORDER(tb->tb_path, h) - 1;
	else {
		order = B_NR_ITEMS(l);
		f = l;
	}

	return (MAX_CHILD_SIZE(f) - dc_size(B_N_CHILD(f, order)));
}

/* Get free space of the right neighbor,
 * which is stored in the parent node of the right neighbor.
 */
static int get_rfree(struct tree_balance *tb, int h)
{
	struct buffer_head *r, *f;
	int order;

	if ((f = PATH_H_PPARENT(tb->tb_path, h)) == NULL ||
	    (r = tb->FR[h]) == NULL)
		return 0;

	if (f == r)
		order = PATH_H_B_ITEM_ORDER(tb->tb_path, h) + 1;
	else {
		order = 0;
		f = r;
	}

	return (MAX_CHILD_SIZE(f) - dc_size(B_N_CHILD(f, order)));

}

/* Check whether left neighbor is in memory. */
static int is_left_neighbor_in_cache(struct tree_balance *tb, int h)
{
	struct buffer_head *father, *left;
	struct super_block *sb = tb->tb_sb;
	b_blocknr_t left_neighbor_blocknr;
	int left_neighbor_position;

	/* Father of the left neighbor does not exist. */
	if (!tb->FL[h])
		return 0;

	/* Calculate father of the node to be balanced. */
	father = PATH_H_PBUFFER(tb->tb_path, h + 1);

	RFALSE(!father ||
	       !B_IS_IN_TREE(father) ||
	       !B_IS_IN_TREE(tb->FL[h]) ||
	       !buffer_uptodate(father) ||
	       !buffer_uptodate(tb->FL[h]),
	       "vs-8165: F[h] (%b) or FL[h] (%b) is invalid",
	       father, tb->FL[h]);

	/* Get position of the pointer to the left neighbor into the left father. */
	left_neighbor_position = (father == tb->FL[h]) ?
	    tb->lkey[h] : B_NR_ITEMS(tb->FL[h]);
	/* Get left neighbor block number. */
	left_neighbor_blocknr =
	    B_N_CHILD_NUM(tb->FL[h], left_neighbor_position);
	/* Look for the left neighbor in the cache. */
	if ((left = sb_find_get_block(sb, left_neighbor_blocknr))) {

		RFALSE(buffer_uptodate(left) && !B_IS_IN_TREE(left),
		       "vs-8170: left neighbor (%b %z) is not in the tree",
		       left, left);
		put_bh(left);
		return 1;
	}

	return 0;
}

#define LEFT_PARENTS  'l'
#define RIGHT_PARENTS 'r'

static void decrement_key(struct cpu_key *key)
{
	// call item specific function for this key
	item_ops[cpu_key_k_type(key)]->decrement_key(key);
}

/* Calculate far left/right parent of the left/right neighbor of the current node, that
 * is calculate the left/right (FL[h]/FR[h]) neighbor of the parent F[h].
 * Calculate left/right common parent of the current node and L[h]/R[h].
 * Calculate left/right delimiting key position.
 * Returns:	PATH_INCORRECT   - path in the tree is not correct;
 		SCHEDULE_OCCURRED - schedule occurred while the function worked;
 *	        CARRY_ON         - schedule didn't occur while the function worked;
 */
static int get_far_parent(struct tree_balance *tb,
			  int h,
			  struct buffer_head **pfather,
			  struct buffer_head **pcom_father, char c_lr_par)
{
	struct buffer_head *parent;
	INITIALIZE_PATH(s_path_to_neighbor_father);
	struct treepath *path = tb->tb_path;
	struct cpu_key s_lr_father_key;
	int counter,
	    position = INT_MAX,
	    first_last_position = 0,
	    path_offset = PATH_H_PATH_OFFSET(path, h);

	/* Starting from F[h] go upwards in the tree, and look for the common
	   ancestor of F[h], and its neighbor l/r, that should be obtained. */

	counter = path_offset;

	RFALSE(counter < FIRST_PATH_ELEMENT_OFFSET,
	       "PAP-8180: invalid path length");

	for (; counter > FIRST_PATH_ELEMENT_OFFSET; counter--) {
		/* Check whether parent of the current buffer in the path is really parent in the tree. */
		if (!B_IS_IN_TREE
		    (parent = PATH_OFFSET_PBUFFER(path, counter - 1)))
			return REPEAT_SEARCH;
		/* Check whether position in the parent is correct. */
		if ((position =
		     PATH_OFFSET_POSITION(path,
					  counter - 1)) >
		    B_NR_ITEMS(parent))
			return REPEAT_SEARCH;
		/* Check whether parent at the path really points to the child. */
		if (B_N_CHILD_NUM(parent, position) !=
		    PATH_OFFSET_PBUFFER(path, counter)->b_blocknr)
			return REPEAT_SEARCH;
		/* Return delimiting key if position in the parent is not equal to first/last one. */
		if (c_lr_par == RIGHT_PARENTS)
			first_last_position = B_NR_ITEMS(parent);
		if (position != first_last_position) {
			*pcom_father = parent;
			get_bh(*pcom_father);
			/*(*pcom_father = parent)->b_count++; */
			break;
		}
	}

	/* if we are in the root of the tree, then there is no common father */
	if (counter == FIRST_PATH_ELEMENT_OFFSET) {
		/* Check whether first buffer in the path is the root of the tree. */
		if (PATH_OFFSET_PBUFFER
		    (tb->tb_path,
		     FIRST_PATH_ELEMENT_OFFSET)->b_blocknr ==
		    SB_ROOT_BLOCK(tb->tb_sb)) {
			*pfather = *pcom_father = NULL;
			return CARRY_ON;
		}
		return REPEAT_SEARCH;
	}

	RFALSE(B_LEVEL(*pcom_father) <= DISK_LEAF_NODE_LEVEL,
	       "PAP-8185: (%b %z) level too small",
	       *pcom_father, *pcom_father);

	/* Check whether the common parent is locked. */

	if (buffer_locked(*pcom_father)) {

		/* Release the write lock while the buffer is busy */
		int depth = reiserfs_write_unlock_nested(tb->tb_sb);
		__wait_on_buffer(*pcom_father);
		reiserfs_write_lock_nested(tb->tb_sb, depth);
		if (FILESYSTEM_CHANGED_TB(tb)) {
			brelse(*pcom_father);
			return REPEAT_SEARCH;
		}
	}

	/* So, we got common parent of the current node and its left/right neighbor.
	   Now we are geting the parent of the left/right neighbor. */

	/* Form key to get parent of the left/right neighbor. */
	le_key2cpu_key(&s_lr_father_key,
		       B_N_PDELIM_KEY(*pcom_father,
				      (c_lr_par ==
				       LEFT_PARENTS) ? (tb->lkey[h - 1] =
							position -
							1) : (tb->rkey[h -
									   1] =
							      position)));

	if (c_lr_par == LEFT_PARENTS)
		decrement_key(&s_lr_father_key);

	if (search_by_key
	    (tb->tb_sb, &s_lr_father_key, &s_path_to_neighbor_father,
	     h + 1) == IO_ERROR)
		// path is released
		return IO_ERROR;

	if (FILESYSTEM_CHANGED_TB(tb)) {
		pathrelse(&s_path_to_neighbor_father);
		brelse(*pcom_father);
		return REPEAT_SEARCH;
	}

	*pfather = PATH_PLAST_BUFFER(&s_path_to_neighbor_father);

	RFALSE(B_LEVEL(*pfather) != h + 1,
	       "PAP-8190: (%b %z) level too small", *pfather, *pfather);
	RFALSE(s_path_to_neighbor_father.path_length <
	       FIRST_PATH_ELEMENT_OFFSET, "PAP-8192: path length is too small");

	s_path_to_neighbor_father.path_length--;
	pathrelse(&s_path_to_neighbor_father);
	return CARRY_ON;
}

/* Get parents of neighbors of node in the path(S[path_offset]) and common parents of
 * S[path_offset] and L[path_offset]/R[path_offset]: F[path_offset], FL[path_offset],
 * FR[path_offset], CFL[path_offset], CFR[path_offset].
 * Calculate numbers of left and right delimiting keys position: lkey[path_offset], rkey[path_offset].
 * Returns:	SCHEDULE_OCCURRED - schedule occurred while the function worked;
 *	        CARRY_ON - schedule didn't occur while the function worked;
 */
static int get_parents(struct tree_balance *tb, int h)
{
	struct treepath *path = tb->tb_path;
	int position,
	    ret,
	    path_offset = PATH_H_PATH_OFFSET(tb->tb_path, h);
	struct buffer_head *curf, *curcf;

	/* Current node is the root of the tree or will be root of the tree */
	if (path_offset <= FIRST_PATH_ELEMENT_OFFSET) {
		/* The root can not have parents.
		   Release nodes which previously were obtained as parents of the current node neighbors. */
		brelse(tb->FL[h]);
		brelse(tb->CFL[h]);
		brelse(tb->FR[h]);
		brelse(tb->CFR[h]);
		tb->FL[h]  = NULL;
		tb->CFL[h] = NULL;
		tb->FR[h]  = NULL;
		tb->CFR[h] = NULL;
		return CARRY_ON;
	}

	/* Get parent FL[path_offset] of L[path_offset]. */
	position = PATH_OFFSET_POSITION(path, path_offset - 1);
	if (position) {
		/* Current node is not the first child of its parent. */
		curf = PATH_OFFSET_PBUFFER(path, path_offset - 1);
		curcf = PATH_OFFSET_PBUFFER(path, path_offset - 1);
		get_bh(curf);
		get_bh(curf);
		tb->lkey[h] = position - 1;
	} else {
		/* Calculate current parent of L[path_offset], which is the left neighbor of the current node.
		   Calculate current common parent of L[path_offset] and the current node. Note that
		   CFL[path_offset] not equal FL[path_offset] and CFL[path_offset] not equal F[path_offset].
		   Calculate lkey[path_offset]. */
		if ((ret = get_far_parent(tb, h + 1, &curf,
						  &curcf,
						  LEFT_PARENTS)) != CARRY_ON)
			return ret;
	}

	brelse(tb->FL[h]);
	tb->FL[h] = curf;	/* New initialization of FL[h]. */
	brelse(tb->CFL[h]);
	tb->CFL[h] = curcf;	/* New initialization of CFL[h]. */

	RFALSE((curf && !B_IS_IN_TREE(curf)) ||
	       (curcf && !B_IS_IN_TREE(curcf)),
	       "PAP-8195: FL (%b) or CFL (%b) is invalid", curf, curcf);

/* Get parent FR[h] of R[h]. */

/* Current node is the last child of F[h]. FR[h] != F[h]. */
	if (position == B_NR_ITEMS(PATH_H_PBUFFER(path, h + 1))) {
/* Calculate current parent of R[h], which is the right neighbor of F[h].
   Calculate current common parent of R[h] and current node. Note that CFR[h]
   not equal FR[path_offset] and CFR[h] not equal F[h]. */
		if ((ret =
		     get_far_parent(tb, h + 1, &curf, &curcf,
				    RIGHT_PARENTS)) != CARRY_ON)
			return ret;
	} else {
/* Current node is not the last child of its parent F[h]. */
		curf = PATH_OFFSET_PBUFFER(path, path_offset - 1);
		curcf = PATH_OFFSET_PBUFFER(path, path_offset - 1);
		get_bh(curf);
		get_bh(curf);
		tb->rkey[h] = position;
	}

	brelse(tb->FR[h]);
	/* New initialization of FR[path_offset]. */
	tb->FR[h] = curf;

	brelse(tb->CFR[h]);
	/* New initialization of CFR[path_offset]. */
	tb->CFR[h] = curcf;

	RFALSE((curf && !B_IS_IN_TREE(curf)) ||
	       (curcf && !B_IS_IN_TREE(curcf)),
	       "PAP-8205: FR (%b) or CFR (%b) is invalid", curf, curcf);

	return CARRY_ON;
}

/* it is possible to remove node as result of shiftings to
   neighbors even when we insert or paste item. */
static inline int can_node_be_removed(int mode, int lfree, int sfree, int rfree,
				      struct tree_balance *tb, int h)
{
	struct buffer_head *Sh = PATH_H_PBUFFER(tb->tb_path, h);
	int levbytes = tb->insert_size[h];
	struct item_head *ih;
	struct reiserfs_key *r_key = NULL;

	ih = B_N_PITEM_HEAD(Sh, 0);
	if (tb->CFR[h])
		r_key = B_N_PDELIM_KEY(tb->CFR[h], tb->rkey[h]);

	if (lfree + rfree + sfree < MAX_CHILD_SIZE(Sh) + levbytes
	    /* shifting may merge items which might save space */
	    -
	    ((!h
	      && op_is_left_mergeable(&(ih->ih_key), Sh->b_size)) ? IH_SIZE : 0)
	    -
	    ((!h && r_key
	      && op_is_left_mergeable(r_key, Sh->b_size)) ? IH_SIZE : 0)
	    + ((h) ? KEY_SIZE : 0)) {
		/* node can not be removed */
		if (sfree >= levbytes) {	/* new item fits into node S[h] without any shifting */
			if (!h)
				tb->s0num =
				    B_NR_ITEMS(Sh) +
				    ((mode == M_INSERT) ? 1 : 0);
			set_parameters(tb, h, 0, 0, 1, NULL, -1, -1);
			return NO_BALANCING_NEEDED;
		}
	}
	PROC_INFO_INC(tb->tb_sb, can_node_be_removed[h]);
	return !NO_BALANCING_NEEDED;
}

/* Check whether current node S[h] is balanced when increasing its size by
 * Inserting or Pasting.
 * Calculate parameters for balancing for current level h.
 * Parameters:
 *	tb	tree_balance structure;
 *	h	current level of the node;
 *	inum	item number in S[h];
 *	mode	i - insert, p - paste;
 * Returns:	1 - schedule occurred;
 *	        0 - balancing for higher levels needed;
 *	       -1 - no balancing for higher levels needed;
 *	       -2 - no disk space.
 */
/* ip means Inserting or Pasting */
static int ip_check_balance(struct tree_balance *tb, int h)
{
	struct virtual_node *vn = tb->tb_vn;
	int levbytes,		/* Number of bytes that must be inserted into (value
				   is negative if bytes are deleted) buffer which
				   contains node being balanced.  The mnemonic is
				   that the attempted change in node space used level
				   is levbytes bytes. */
	 ret;

	int lfree, sfree, rfree /* free space in L, S and R */ ;

	/* nver is short for number of vertixes, and lnver is the number if
	   we shift to the left, rnver is the number if we shift to the
	   right, and lrnver is the number if we shift in both directions.
	   The goal is to minimize first the number of vertixes, and second,
	   the number of vertixes whose contents are changed by shifting,
	   and third the number of uncached vertixes whose contents are
	   changed by shifting and must be read from disk.  */
	int nver, lnver, rnver, lrnver;

	/* used at leaf level only, S0 = S[0] is the node being balanced,
	   sInum [ I = 0,1,2 ] is the number of items that will
	   remain in node SI after balancing.  S1 and S2 are new
	   nodes that might be created. */

	/* we perform 8 calls to get_num_ver().  For each call we calculate five parameters.
	   where 4th parameter is s1bytes and 5th - s2bytes
	 */
	short snum012[40] = { 0, };	/* s0num, s1num, s2num for 8 cases
					   0,1 - do not shift and do not shift but bottle
					   2 - shift only whole item to left
					   3 - shift to left and bottle as much as possible
					   4,5 - shift to right (whole items and as much as possible
					   6,7 - shift to both directions (whole items and as much as possible)
					 */

	/* Sh is the node whose balance is currently being checked */
	struct buffer_head *Sh;

	Sh = PATH_H_PBUFFER(tb->tb_path, h);
	levbytes = tb->insert_size[h];

	/* Calculate balance parameters for creating new root. */
	if (!Sh) {
		if (!h)
			reiserfs_panic(tb->tb_sb, "vs-8210",
				       "S[0] can not be 0");
		switch (ret = get_empty_nodes(tb, h)) {
		case CARRY_ON:
			set_parameters(tb, h, 0, 0, 1, NULL, -1, -1);
			return NO_BALANCING_NEEDED;	/* no balancing for higher levels needed */

		case NO_DISK_SPACE:
		case REPEAT_SEARCH:
			return ret;
		default:
			reiserfs_panic(tb->tb_sb, "vs-8215", "incorrect "
				       "return value of get_empty_nodes");
		}
	}

	if ((ret = get_parents(tb, h)) != CARRY_ON)	/* get parents of S[h] neighbors. */
		return ret;

	sfree = B_FREE_SPACE(Sh);

	/* get free space of neighbors */
	rfree = get_rfree(tb, h);
	lfree = get_lfree(tb, h);

	if (can_node_be_removed(vn->vn_mode, lfree, sfree, rfree, tb, h) ==
	    NO_BALANCING_NEEDED)
		/* and new item fits into node S[h] without any shifting */
		return NO_BALANCING_NEEDED;

	create_virtual_node(tb, h);

	/*
	   determine maximal number of items we can shift to the left neighbor (in tb structure)
	   and the maximal number of bytes that can flow to the left neighbor
	   from the left most liquid item that cannot be shifted from S[0] entirely (returned value)
	 */
	check_left(tb, h, lfree);

	/*
	   determine maximal number of items we can shift to the right neighbor (in tb structure)
	   and the maximal number of bytes that can flow to the right neighbor
	   from the right most liquid item that cannot be shifted from S[0] entirely (returned value)
	 */
	check_right(tb, h, rfree);

	/* all contents of internal node S[h] can be moved into its
	   neighbors, S[h] will be removed after balancing */
	if (h && (tb->rnum[h] + tb->lnum[h] >= vn->vn_nr_item + 1)) {
		int to_r;

		/* Since we are working on internal nodes, and our internal
		   nodes have fixed size entries, then we can balance by the
		   number of items rather than the space they consume.  In this
		   routine we set the left node equal to the right node,
		   allowing a difference of less than or equal to 1 child
		   pointer. */
		to_r =
		    ((MAX_NR_KEY(Sh) << 1) + 2 - tb->lnum[h] - tb->rnum[h] +
		     vn->vn_nr_item + 1) / 2 - (MAX_NR_KEY(Sh) + 1 -
						tb->rnum[h]);
		set_parameters(tb, h, vn->vn_nr_item + 1 - to_r, to_r, 0, NULL,
			       -1, -1);
		return CARRY_ON;
	}

	/* this checks balance condition, that any two neighboring nodes can not fit in one node */
	RFALSE(h &&
	       (tb->lnum[h] >= vn->vn_nr_item + 1 ||
		tb->rnum[h] >= vn->vn_nr_item + 1),
	       "vs-8220: tree is not balanced on internal level");
	RFALSE(!h && ((tb->lnum[h] >= vn->vn_nr_item && (tb->lbytes == -1)) ||
		      (tb->rnum[h] >= vn->vn_nr_item && (tb->rbytes == -1))),
	       "vs-8225: tree is not balanced on leaf level");

	/* all contents of S[0] can be moved into its neighbors
	   S[0] will be removed after balancing. */
	if (!h && is_leaf_removable(tb))
		return CARRY_ON;

	/* why do we perform this check here rather than earlier??
	   Answer: we can win 1 node in some cases above. Moreover we
	   checked it above, when we checked, that S[0] is not removable
	   in principle */
	if (sfree >= levbytes) {	/* new item fits into node S[h] without any shifting */
		if (!h)
			tb->s0num = vn->vn_nr_item;
		set_parameters(tb, h, 0, 0, 1, NULL, -1, -1);
		return NO_BALANCING_NEEDED;
	}

	{
		int lpar, rpar, nset, lset, rset, lrset;
		/*
		 * regular overflowing of the node
		 */

		/* get_num_ver works in 2 modes (FLOW & NO_FLOW)
		   lpar, rpar - number of items we can shift to left/right neighbor (including splitting item)
		   nset, lset, rset, lrset - shows, whether flowing items give better packing
		 */
#define FLOW 1
#define NO_FLOW 0		/* do not any splitting */

		/* we choose one the following */
#define NOTHING_SHIFT_NO_FLOW	0
#define NOTHING_SHIFT_FLOW	5
#define LEFT_SHIFT_NO_FLOW	10
#define LEFT_SHIFT_FLOW		15
#define RIGHT_SHIFT_NO_FLOW	20
#define RIGHT_SHIFT_FLOW	25
#define LR_SHIFT_NO_FLOW	30
#define LR_SHIFT_FLOW		35

		lpar = tb->lnum[h];
		rpar = tb->rnum[h];

		/* calculate number of blocks S[h] must be split into when
		   nothing is shifted to the neighbors,
		   as well as number of items in each part of the split node (s012 numbers),
		   and number of bytes (s1bytes) of the shared drop which flow to S1 if any */
		nset = NOTHING_SHIFT_NO_FLOW;
		nver = get_num_ver(vn->vn_mode, tb, h,
				   0, -1, h ? vn->vn_nr_item : 0, -1,
				   snum012, NO_FLOW);

		if (!h) {
			int nver1;

			/* note, that in this case we try to bottle between S[0] and S1 (S1 - the first new node) */
			nver1 = get_num_ver(vn->vn_mode, tb, h,
					    0, -1, 0, -1,
					    snum012 + NOTHING_SHIFT_FLOW, FLOW);
			if (nver > nver1)
				nset = NOTHING_SHIFT_FLOW, nver = nver1;
		}

		/* calculate number of blocks S[h] must be split into when
		   l_shift_num first items and l_shift_bytes of the right most
		   liquid item to be shifted are shifted to the left neighbor,
		   as well as number of items in each part of the splitted node (s012 numbers),
		   and number of bytes (s1bytes) of the shared drop which flow to S1 if any
		 */
		lset = LEFT_SHIFT_NO_FLOW;
		lnver = get_num_ver(vn->vn_mode, tb, h,
				    lpar - ((h || tb->lbytes == -1) ? 0 : 1),
				    -1, h ? vn->vn_nr_item : 0, -1,
				    snum012 + LEFT_SHIFT_NO_FLOW, NO_FLOW);
		if (!h) {
			int lnver1;

			lnver1 = get_num_ver(vn->vn_mode, tb, h,
					     lpar -
					     ((tb->lbytes != -1) ? 1 : 0),
					     tb->lbytes, 0, -1,
					     snum012 + LEFT_SHIFT_FLOW, FLOW);
			if (lnver > lnver1)
				lset = LEFT_SHIFT_FLOW, lnver = lnver1;
		}

		/* calculate number of blocks S[h] must be split into when
		   r_shift_num first items and r_shift_bytes of the left most
		   liquid item to be shifted are shifted to the right neighbor,
		   as well as number of items in each part of the splitted node (s012 numbers),
		   and number of bytes (s1bytes) of the shared drop which flow to S1 if any
		 */
		rset = RIGHT_SHIFT_NO_FLOW;
		rnver = get_num_ver(vn->vn_mode, tb, h,
				    0, -1,
				    h ? (vn->vn_nr_item - rpar) : (rpar -
								   ((tb->
								     rbytes !=
								     -1) ? 1 :
								    0)), -1,
				    snum012 + RIGHT_SHIFT_NO_FLOW, NO_FLOW);
		if (!h) {
			int rnver1;

			rnver1 = get_num_ver(vn->vn_mode, tb, h,
					     0, -1,
					     (rpar -
					      ((tb->rbytes != -1) ? 1 : 0)),
					     tb->rbytes,
					     snum012 + RIGHT_SHIFT_FLOW, FLOW);

			if (rnver > rnver1)
				rset = RIGHT_SHIFT_FLOW, rnver = rnver1;
		}

		/* calculate number of blocks S[h] must be split into when
		   items are shifted in both directions,
		   as well as number of items in each part of the splitted node (s012 numbers),
		   and number of bytes (s1bytes) of the shared drop which flow to S1 if any
		 */
		lrset = LR_SHIFT_NO_FLOW;
		lrnver = get_num_ver(vn->vn_mode, tb, h,
				     lpar - ((h || tb->lbytes == -1) ? 0 : 1),
				     -1,
				     h ? (vn->vn_nr_item - rpar) : (rpar -
								    ((tb->
								      rbytes !=
								      -1) ? 1 :
								     0)), -1,
				     snum012 + LR_SHIFT_NO_FLOW, NO_FLOW);
		if (!h) {
			int lrnver1;

			lrnver1 = get_num_ver(vn->vn_mode, tb, h,
					      lpar -
					      ((tb->lbytes != -1) ? 1 : 0),
					      tb->lbytes,
					      (rpar -
					       ((tb->rbytes != -1) ? 1 : 0)),
					      tb->rbytes,
					      snum012 + LR_SHIFT_FLOW, FLOW);
			if (lrnver > lrnver1)
				lrset = LR_SHIFT_FLOW, lrnver = lrnver1;
		}

		/* Our general shifting strategy is:
		   1) to minimized number of new nodes;
		   2) to minimized number of neighbors involved in shifting;
		   3) to minimized number of disk reads; */

		/* we can win TWO or ONE nodes by shifting in both directions */
		if (lrnver < lnver && lrnver < rnver) {
			RFALSE(h &&
			       (tb->lnum[h] != 1 ||
				tb->rnum[h] != 1 ||
				lrnver != 1 || rnver != 2 || lnver != 2
				|| h != 1), "vs-8230: bad h");
			if (lrset == LR_SHIFT_FLOW)
				set_parameters(tb, h, tb->lnum[h], tb->rnum[h],
					       lrnver, snum012 + lrset,
					       tb->lbytes, tb->rbytes);
			else
				set_parameters(tb, h,
					       tb->lnum[h] -
					       ((tb->lbytes == -1) ? 0 : 1),
					       tb->rnum[h] -
					       ((tb->rbytes == -1) ? 0 : 1),
					       lrnver, snum012 + lrset, -1, -1);

			return CARRY_ON;
		}

		/* if shifting doesn't lead to better packing then don't shift */
		if (nver == lrnver) {
			set_parameters(tb, h, 0, 0, nver, snum012 + nset, -1,
				       -1);
			return CARRY_ON;
		}

		/* now we know that for better packing shifting in only one
		   direction either to the left or to the right is required */

		/*  if shifting to the left is better than shifting to the right */
		if (lnver < rnver) {
			SET_PAR_SHIFT_LEFT;
			return CARRY_ON;
		}

		/* if shifting to the right is better than shifting to the left */
		if (lnver > rnver) {
			SET_PAR_SHIFT_RIGHT;
			return CARRY_ON;
		}

		/* now shifting in either direction gives the same number
		   of nodes and we can make use of the cached neighbors */
		if (is_left_neighbor_in_cache(tb, h)) {
			SET_PAR_SHIFT_LEFT;
			return CARRY_ON;
		}

		/* shift to the right independently on whether the right neighbor in cache or not */
		SET_PAR_SHIFT_RIGHT;
		return CARRY_ON;
	}
}

/* Check whether current node S[h] is balanced when Decreasing its size by
 * Deleting or Cutting for INTERNAL node of S+tree.
 * Calculate parameters for balancing for current level h.
 * Parameters:
 *	tb	tree_balance structure;
 *	h	current level of the node;
 *	inum	item number in S[h];
 *	mode	i - insert, p - paste;
 * Returns:	1 - schedule occurred;
 *	        0 - balancing for higher levels needed;
 *	       -1 - no balancing for higher levels needed;
 *	       -2 - no disk space.
 *
 * Note: Items of internal nodes have fixed size, so the balance condition for
 * the internal part of S+tree is as for the B-trees.
 */
static int dc_check_balance_internal(struct tree_balance *tb, int h)
{
	struct virtual_node *vn = tb->tb_vn;

	/* Sh is the node whose balance is currently being checked,
	   and Fh is its father.  */
	struct buffer_head *Sh, *Fh;
	int maxsize, ret;
	int lfree, rfree /* free space in L and R */ ;

	Sh = PATH_H_PBUFFER(tb->tb_path, h);
	Fh = PATH_H_PPARENT(tb->tb_path, h);

	maxsize = MAX_CHILD_SIZE(Sh);

/*   using tb->insert_size[h], which is negative in this case, create_virtual_node calculates: */
/*   new_nr_item = number of items node would have if operation is */
/* 	performed without balancing (new_nr_item); */
	create_virtual_node(tb, h);

	if (!Fh) {		/* S[h] is the root. */
		if (vn->vn_nr_item > 0) {
			set_parameters(tb, h, 0, 0, 1, NULL, -1, -1);
			return NO_BALANCING_NEEDED;	/* no balancing for higher levels needed */
		}
		/* new_nr_item == 0.
		 * Current root will be deleted resulting in
		 * decrementing the tree height. */
		set_parameters(tb, h, 0, 0, 0, NULL, -1, -1);
		return CARRY_ON;
	}

	if ((ret = get_parents(tb, h)) != CARRY_ON)
		return ret;

	/* get free space of neighbors */
	rfree = get_rfree(tb, h);
	lfree = get_lfree(tb, h);

	/* determine maximal number of items we can fit into neighbors */
	check_left(tb, h, lfree);
	check_right(tb, h, rfree);

	if (vn->vn_nr_item >= MIN_NR_KEY(Sh)) {	/* Balance condition for the internal node is valid.
						 * In this case we balance only if it leads to better packing. */
		if (vn->vn_nr_item == MIN_NR_KEY(Sh)) {	/* Here we join S[h] with one of its neighbors,
							 * which is impossible with greater values of new_nr_item. */
			if (tb->lnum[h] >= vn->vn_nr_item + 1) {
				/* All contents of S[h] can be moved to L[h]. */
				int n;
				int order_L;

				order_L =
				    ((n =
				      PATH_H_B_ITEM_ORDER(tb->tb_path,
							  h)) ==
				     0) ? B_NR_ITEMS(tb->FL[h]) : n - 1;
				n = dc_size(B_N_CHILD(tb->FL[h], order_L)) /
				    (DC_SIZE + KEY_SIZE);
				set_parameters(tb, h, -n - 1, 0, 0, NULL, -1,
					       -1);
				return CARRY_ON;
			}

			if (tb->rnum[h] >= vn->vn_nr_item + 1) {
				/* All contents of S[h] can be moved to R[h]. */
				int n;
				int order_R;

				order_R =
				    ((n =
				      PATH_H_B_ITEM_ORDER(tb->tb_path,
							  h)) ==
				     B_NR_ITEMS(Fh)) ? 0 : n + 1;
				n = dc_size(B_N_CHILD(tb->FR[h], order_R)) /
				    (DC_SIZE + KEY_SIZE);
				set_parameters(tb, h, 0, -n - 1, 0, NULL, -1,
					       -1);
				return CARRY_ON;
			}
		}

		if (tb->rnum[h] + tb->lnum[h] >= vn->vn_nr_item + 1) {
			/* All contents of S[h] can be moved to the neighbors (L[h] & R[h]). */
			int to_r;

			to_r =
			    ((MAX_NR_KEY(Sh) << 1) + 2 - tb->lnum[h] -
			     tb->rnum[h] + vn->vn_nr_item + 1) / 2 -
			    (MAX_NR_KEY(Sh) + 1 - tb->rnum[h]);
			set_parameters(tb, h, vn->vn_nr_item + 1 - to_r, to_r,
				       0, NULL, -1, -1);
			return CARRY_ON;
		}

		/* Balancing does not lead to better packing. */
		set_parameters(tb, h, 0, 0, 1, NULL, -1, -1);
		return NO_BALANCING_NEEDED;
	}

	/* Current node contain insufficient number of items. Balancing is required. */
	/* Check whether we can merge S[h] with left neighbor. */
	if (tb->lnum[h] >= vn->vn_nr_item + 1)
		if (is_left_neighbor_in_cache(tb, h)
		    || tb->rnum[h] < vn->vn_nr_item + 1 || !tb->FR[h]) {
			int n;
			int order_L;

			order_L =
			    ((n =
			      PATH_H_B_ITEM_ORDER(tb->tb_path,
						  h)) ==
			     0) ? B_NR_ITEMS(tb->FL[h]) : n - 1;
			n = dc_size(B_N_CHILD(tb->FL[h], order_L)) / (DC_SIZE +
								      KEY_SIZE);
			set_parameters(tb, h, -n - 1, 0, 0, NULL, -1, -1);
			return CARRY_ON;
		}

	/* Check whether we can merge S[h] with right neighbor. */
	if (tb->rnum[h] >= vn->vn_nr_item + 1) {
		int n;
		int order_R;

		order_R =
		    ((n =
		      PATH_H_B_ITEM_ORDER(tb->tb_path,
					  h)) == B_NR_ITEMS(Fh)) ? 0 : (n + 1);
		n = dc_size(B_N_CHILD(tb->FR[h], order_R)) / (DC_SIZE +
							      KEY_SIZE);
		set_parameters(tb, h, 0, -n - 1, 0, NULL, -1, -1);
		return CARRY_ON;
	}

	/* All contents of S[h] can be moved to the neighbors (L[h] & R[h]). */
	if (tb->rnum[h] + tb->lnum[h] >= vn->vn_nr_item + 1) {
		int to_r;

		to_r =
		    ((MAX_NR_KEY(Sh) << 1) + 2 - tb->lnum[h] - tb->rnum[h] +
		     vn->vn_nr_item + 1) / 2 - (MAX_NR_KEY(Sh) + 1 -
						tb->rnum[h]);
		set_parameters(tb, h, vn->vn_nr_item + 1 - to_r, to_r, 0, NULL,
			       -1, -1);
		return CARRY_ON;
	}

	/* For internal nodes try to borrow item from a neighbor */
	RFALSE(!tb->FL[h] && !tb->FR[h], "vs-8235: trying to borrow for root");

	/* Borrow one or two items from caching neighbor */
	if (is_left_neighbor_in_cache(tb, h) || !tb->FR[h]) {
		int from_l;

		from_l =
		    (MAX_NR_KEY(Sh) + 1 - tb->lnum[h] + vn->vn_nr_item +
		     1) / 2 - (vn->vn_nr_item + 1);
		set_parameters(tb, h, -from_l, 0, 1, NULL, -1, -1);
		return CARRY_ON;
	}

	set_parameters(tb, h, 0,
		       -((MAX_NR_KEY(Sh) + 1 - tb->rnum[h] + vn->vn_nr_item +
			  1) / 2 - (vn->vn_nr_item + 1)), 1, NULL, -1, -1);
	return CARRY_ON;
}

/* Check whether current node S[h] is balanced when Decreasing its size by
 * Deleting or Truncating for LEAF node of S+tree.
 * Calculate parameters for balancing for current level h.
 * Parameters:
 *	tb	tree_balance structure;
 *	h	current level of the node;
 *	inum	item number in S[h];
 *	mode	i - insert, p - paste;
 * Returns:	1 - schedule occurred;
 *	        0 - balancing for higher levels needed;
 *	       -1 - no balancing for higher levels needed;
 *	       -2 - no disk space.
 */
static int dc_check_balance_leaf(struct tree_balance *tb, int h)
{
	struct virtual_node *vn = tb->tb_vn;

	/* Number of bytes that must be deleted from
	   (value is negative if bytes are deleted) buffer which
	   contains node being balanced.  The mnemonic is that the
	   attempted change in node space used level is levbytes bytes. */
	int levbytes;
	/* the maximal item size */
	int maxsize, ret;
	/* S0 is the node whose balance is currently being checked,
	   and F0 is its father.  */
	struct buffer_head *S0, *F0;
	int lfree, rfree /* free space in L and R */ ;

	S0 = PATH_H_PBUFFER(tb->tb_path, 0);
	F0 = PATH_H_PPARENT(tb->tb_path, 0);

	levbytes = tb->insert_size[h];

	maxsize = MAX_CHILD_SIZE(S0);	/* maximal possible size of an item */

	if (!F0) {		/* S[0] is the root now. */

		RFALSE(-levbytes >= maxsize - B_FREE_SPACE(S0),
		       "vs-8240: attempt to create empty buffer tree");

		set_parameters(tb, h, 0, 0, 1, NULL, -1, -1);
		return NO_BALANCING_NEEDED;
	}

	if ((ret = get_parents(tb, h)) != CARRY_ON)
		return ret;

	/* get free space of neighbors */
	rfree = get_rfree(tb, h);
	lfree = get_lfree(tb, h);

	create_virtual_node(tb, h);

	/* if 3 leaves can be merge to one, set parameters and return */
	if (are_leaves_removable(tb, lfree, rfree))
		return CARRY_ON;

	/* determine maximal number of items we can shift to the left/right  neighbor
	   and the maximal number of bytes that can flow to the left/right neighbor
	   from the left/right most liquid item that cannot be shifted from S[0] entirely
	 */
	check_left(tb, h, lfree);
	check_right(tb, h, rfree);

	/* check whether we can merge S with left neighbor. */
	if (tb->lnum[0] >= vn->vn_nr_item && tb->lbytes == -1)
		if (is_left_neighbor_in_cache(tb, h) || ((tb->rnum[0] - ((tb->rbytes == -1) ? 0 : 1)) < vn->vn_nr_item) ||	/* S can not be merged with R */
		    !tb->FR[h]) {

			RFALSE(!tb->FL[h],
			       "vs-8245: dc_check_balance_leaf: FL[h] must exist");

			/* set parameter to merge S[0] with its left neighbor */
			set_parameters(tb, h, -1, 0, 0, NULL, -1, -1);
			return CARRY_ON;
		}

	/* check whether we can merge S[0] with right neighbor. */
	if (tb->rnum[0] >= vn->vn_nr_item && tb->rbytes == -1) {
		set_parameters(tb, h, 0, -1, 0, NULL, -1, -1);
		return CARRY_ON;
	}

	/* All contents of S[0] can be moved to the neighbors (L[0] & R[0]). Set parameters and return */
	if (is_leaf_removable(tb))
		return CARRY_ON;

	/* Balancing is not required. */
	tb->s0num = vn->vn_nr_item;
	set_parameters(tb, h, 0, 0, 1, NULL, -1, -1);
	return NO_BALANCING_NEEDED;
}

/* Check whether current node S[h] is balanced when Decreasing its size by
 * Deleting or Cutting.
 * Calculate parameters for balancing for current level h.
 * Parameters:
 *	tb	tree_balance structure;
 *	h	current level of the node;
 *	inum	item number in S[h];
 *	mode	d - delete, c - cut.
 * Returns:	1 - schedule occurred;
 *	        0 - balancing for higher levels needed;
 *	       -1 - no balancing for higher levels needed;
 *	       -2 - no disk space.
 */
static int dc_check_balance(struct tree_balance *tb, int h)
{
	RFALSE(!(PATH_H_PBUFFER(tb->tb_path, h)),
	       "vs-8250: S is not initialized");

	if (h)
		return dc_check_balance_internal(tb, h);
	else
		return dc_check_balance_leaf(tb, h);
}

/* Check whether current node S[h] is balanced.
 * Calculate parameters for balancing for current level h.
 * Parameters:
 *
 *	tb	tree_balance structure:
 *
 *              tb is a large structure that must be read about in the header file
 *              at the same time as this procedure if the reader is to successfully
 *              understand this procedure
 *
 *	h	current level of the node;
 *	inum	item number in S[h];
 *	mode	i - insert, p - paste, d - delete, c - cut.
 * Returns:	1 - schedule occurred;
 *	        0 - balancing for higher levels needed;
 *	       -1 - no balancing for higher levels needed;
 *	       -2 - no disk space.
 */
static int check_balance(int mode,
			 struct tree_balance *tb,
			 int h,
			 int inum,
			 int pos_in_item,
			 struct item_head *ins_ih, const void *data)
{
	struct virtual_node *vn;

	vn = tb->tb_vn = (struct virtual_node *)(tb->vn_buf);
	vn->vn_free_ptr = (char *)(tb->tb_vn + 1);
	vn->vn_mode = mode;
	vn->vn_affected_item_num = inum;
	vn->vn_pos_in_item = pos_in_item;
	vn->vn_ins_ih = ins_ih;
	vn->vn_data = data;

	RFALSE(mode == M_INSERT && !vn->vn_ins_ih,
	       "vs-8255: ins_ih can not be 0 in insert mode");

	if (tb->insert_size[h] > 0)
		/* Calculate balance parameters when size of node is increasing. */
		return ip_check_balance(tb, h);

	/* Calculate balance parameters when  size of node is decreasing. */
	return dc_check_balance(tb, h);
}

/* Check whether parent at the path is the really parent of the current node.*/
static int get_direct_parent(struct tree_balance *tb, int h)
{
	struct buffer_head *bh;
	struct treepath *path = tb->tb_path;
	int position,
	    path_offset = PATH_H_PATH_OFFSET(tb->tb_path, h);

	/* We are in the root or in the new root. */
	if (path_offset <= FIRST_PATH_ELEMENT_OFFSET) {

		RFALSE(path_offset < FIRST_PATH_ELEMENT_OFFSET - 1,
		       "PAP-8260: invalid offset in the path");

		if (PATH_OFFSET_PBUFFER(path, FIRST_PATH_ELEMENT_OFFSET)->
		    b_blocknr == SB_ROOT_BLOCK(tb->tb_sb)) {
			/* Root is not changed. */
			PATH_OFFSET_PBUFFER(path, path_offset - 1) = NULL;
			PATH_OFFSET_POSITION(path, path_offset - 1) = 0;
			return CARRY_ON;
		}
		return REPEAT_SEARCH;	/* Root is changed and we must recalculate the path. */
	}

	if (!B_IS_IN_TREE
	    (bh = PATH_OFFSET_PBUFFER(path, path_offset - 1)))
		return REPEAT_SEARCH;	/* Parent in the path is not in the tree. */

	if ((position =
	     PATH_OFFSET_POSITION(path,
				  path_offset - 1)) > B_NR_ITEMS(bh))
		return REPEAT_SEARCH;

	if (B_N_CHILD_NUM(bh, position) !=
	    PATH_OFFSET_PBUFFER(path, path_offset)->b_blocknr)
		/* Parent in the path is not parent of the current node in the tree. */
		return REPEAT_SEARCH;

	if (buffer_locked(bh)) {
		int depth = reiserfs_write_unlock_nested(tb->tb_sb);
		__wait_on_buffer(bh);
		reiserfs_write_lock_nested(tb->tb_sb, depth);
		if (FILESYSTEM_CHANGED_TB(tb))
			return REPEAT_SEARCH;
	}

	return CARRY_ON;	/* Parent in the path is unlocked and really parent of the current node.  */
}

/* Using lnum[h] and rnum[h] we should determine what neighbors
 * of S[h] we
 * need in order to balance S[h], and get them if necessary.
 * Returns:	SCHEDULE_OCCURRED - schedule occurred while the function worked;
 *	        CARRY_ON - schedule didn't occur while the function worked;
 */
static int get_neighbors(struct tree_balance *tb, int h)
{
	int child_position,
	    path_offset = PATH_H_PATH_OFFSET(tb->tb_path, h + 1);
	unsigned long son_number;
	struct super_block *sb = tb->tb_sb;
	struct buffer_head *bh;
	int depth;

	PROC_INFO_INC(sb, get_neighbors[h]);

	if (tb->lnum[h]) {
		/* We need left neighbor to balance S[h]. */
		PROC_INFO_INC(sb, need_l_neighbor[h]);
		bh = PATH_OFFSET_PBUFFER(tb->tb_path, path_offset);

		RFALSE(bh == tb->FL[h] &&
		       !PATH_OFFSET_POSITION(tb->tb_path, path_offset),
		       "PAP-8270: invalid position in the parent");

		child_position =
		    (bh ==
		     tb->FL[h]) ? tb->lkey[h] : B_NR_ITEMS(tb->
								       FL[h]);
		son_number = B_N_CHILD_NUM(tb->FL[h], child_position);
		depth = reiserfs_write_unlock_nested(tb->tb_sb);
		bh = sb_bread(sb, son_number);
		reiserfs_write_lock_nested(tb->tb_sb, depth);
		if (!bh)
			return IO_ERROR;
		if (FILESYSTEM_CHANGED_TB(tb)) {
			brelse(bh);
			PROC_INFO_INC(sb, get_neighbors_restart[h]);
			return REPEAT_SEARCH;
		}

		RFALSE(!B_IS_IN_TREE(tb->FL[h]) ||
		       child_position > B_NR_ITEMS(tb->FL[h]) ||
		       B_N_CHILD_NUM(tb->FL[h], child_position) !=
		       bh->b_blocknr, "PAP-8275: invalid parent");
		RFALSE(!B_IS_IN_TREE(bh), "PAP-8280: invalid child");
		RFALSE(!h &&
		       B_FREE_SPACE(bh) !=
		       MAX_CHILD_SIZE(bh) -
		       dc_size(B_N_CHILD(tb->FL[0], child_position)),
		       "PAP-8290: invalid child size of left neighbor");

		brelse(tb->L[h]);
		tb->L[h] = bh;
	}

	/* We need right neighbor to balance S[path_offset]. */
	if (tb->rnum[h]) {	/* We need right neighbor to balance S[path_offset]. */
		PROC_INFO_INC(sb, need_r_neighbor[h]);
		bh = PATH_OFFSET_PBUFFER(tb->tb_path, path_offset);

		RFALSE(bh == tb->FR[h] &&
		       PATH_OFFSET_POSITION(tb->tb_path,
					    path_offset) >=
		       B_NR_ITEMS(bh),
		       "PAP-8295: invalid position in the parent");

		child_position =
		    (bh == tb->FR[h]) ? tb->rkey[h] + 1 : 0;
		son_number = B_N_CHILD_NUM(tb->FR[h], child_position);
		depth = reiserfs_write_unlock_nested(tb->tb_sb);
		bh = sb_bread(sb, son_number);
		reiserfs_write_lock_nested(tb->tb_sb, depth);
		if (!bh)
			return IO_ERROR;
		if (FILESYSTEM_CHANGED_TB(tb)) {
			brelse(bh);
			PROC_INFO_INC(sb, get_neighbors_restart[h]);
			return REPEAT_SEARCH;
		}
		brelse(tb->R[h]);
		tb->R[h] = bh;

		RFALSE(!h
		       && B_FREE_SPACE(bh) !=
		       MAX_CHILD_SIZE(bh) -
		       dc_size(B_N_CHILD(tb->FR[0], child_position)),
		       "PAP-8300: invalid child size of right neighbor (%d != %d - %d)",
		       B_FREE_SPACE(bh), MAX_CHILD_SIZE(bh),
		       dc_size(B_N_CHILD(tb->FR[0], child_position)));

	}
	return CARRY_ON;
}

static int get_virtual_node_size(struct super_block *sb, struct buffer_head *bh)
{
	int max_num_of_items;
	int max_num_of_entries;
	unsigned long blocksize = sb->s_blocksize;

#define MIN_NAME_LEN 1

	max_num_of_items = (blocksize - BLKH_SIZE) / (IH_SIZE + MIN_ITEM_LEN);
	max_num_of_entries = (blocksize - BLKH_SIZE - IH_SIZE) /
	    (DEH_SIZE + MIN_NAME_LEN);

	return sizeof(struct virtual_node) +
	    max(max_num_of_items * sizeof(struct virtual_item),
		sizeof(struct virtual_item) + sizeof(struct direntry_uarea) +
		(max_num_of_entries - 1) * sizeof(__u16));
}

/* maybe we should fail balancing we are going to perform when kmalloc
   fails several times. But now it will loop until kmalloc gets
   required memory */
static int get_mem_for_virtual_node(struct tree_balance *tb)
{
	int check_fs = 0;
	int size;
	char *buf;

	size = get_virtual_node_size(tb->tb_sb, PATH_PLAST_BUFFER(tb->tb_path));

	if (size > tb->vn_buf_size) {
		/* we have to allocate more memory for virtual node */
		if (tb->vn_buf) {
			/* free memory allocated before */
			kfree(tb->vn_buf);
			/* this is not needed if kfree is atomic */
			check_fs = 1;
		}

		/* virtual node requires now more memory */
		tb->vn_buf_size = size;

		/* get memory for virtual item */
		buf = kmalloc(size, GFP_ATOMIC | __GFP_NOWARN);
		if (!buf) {
			/* getting memory with GFP_KERNEL priority may involve
			   balancing now (due to indirect_to_direct conversion on
			   dcache shrinking). So, release path and collected
			   resources here */
			free_buffers_in_tb(tb);
			buf = kmalloc(size, GFP_NOFS);
			if (!buf) {
				tb->vn_buf_size = 0;
			}
			tb->vn_buf = buf;
			schedule();
			return REPEAT_SEARCH;
		}

		tb->vn_buf = buf;
	}

	if (check_fs && FILESYSTEM_CHANGED_TB(tb))
		return REPEAT_SEARCH;

	return CARRY_ON;
}

#ifdef CONFIG_REISERFS_CHECK
static void tb_buffer_sanity_check(struct super_block *sb,
				   struct buffer_head *bh,
				   const char *descr, int level)
{
	if (bh) {
		if (atomic_read(&(bh->b_count)) <= 0)

			reiserfs_panic(sb, "jmacd-1", "negative or zero "
				       "reference counter for buffer %s[%d] "
				       "(%b)", descr, level, bh);

		if (!buffer_uptodate(bh))
			reiserfs_panic(sb, "jmacd-2", "buffer is not up "
				       "to date %s[%d] (%b)",
				       descr, level, bh);

		if (!B_IS_IN_TREE(bh))
			reiserfs_panic(sb, "jmacd-3", "buffer is not "
				       "in tree %s[%d] (%b)",
				       descr, level, bh);

		if (bh->b_bdev != sb->s_bdev)
			reiserfs_panic(sb, "jmacd-4", "buffer has wrong "
				       "device %s[%d] (%b)",
				       descr, level, bh);

		if (bh->b_size != sb->s_blocksize)
			reiserfs_panic(sb, "jmacd-5", "buffer has wrong "
				       "blocksize %s[%d] (%b)",
				       descr, level, bh);

		if (bh->b_blocknr > SB_BLOCK_COUNT(sb))
			reiserfs_panic(sb, "jmacd-6", "buffer block "
				       "number too high %s[%d] (%b)",
				       descr, level, bh);
	}
}
#else
static void tb_buffer_sanity_check(struct super_block *sb,
				   struct buffer_head *bh,
				   const char *descr, int level)
{;
}
#endif

static int clear_all_dirty_bits(struct super_block *s, struct buffer_head *bh)
{
	return reiserfs_prepare_for_journal(s, bh, 0);
}

static int wait_tb_buffers_until_unlocked(struct tree_balance *tb)
{
	struct buffer_head *locked;
#ifdef CONFIG_REISERFS_CHECK
	int repeat_counter = 0;
#endif
	int i;

	do {

		locked = NULL;

		for (i = tb->tb_path->path_length;
		     !locked && i > ILLEGAL_PATH_ELEMENT_OFFSET; i--) {
			if (PATH_OFFSET_PBUFFER(tb->tb_path, i)) {
				/* if I understand correctly, we can only be sure the last buffer
				 ** in the path is in the tree --clm
				 */
#ifdef CONFIG_REISERFS_CHECK
				if (PATH_PLAST_BUFFER(tb->tb_path) ==
				    PATH_OFFSET_PBUFFER(tb->tb_path, i))
					tb_buffer_sanity_check(tb->tb_sb,
							       PATH_OFFSET_PBUFFER
							       (tb->tb_path,
								i), "S",
							       tb->tb_path->
							       path_length - i);
#endif
				if (!clear_all_dirty_bits(tb->tb_sb,
							  PATH_OFFSET_PBUFFER
							  (tb->tb_path,
							   i))) {
					locked =
					    PATH_OFFSET_PBUFFER(tb->tb_path,
								i);
				}
			}
		}

		for (i = 0; !locked && i < MAX_HEIGHT && tb->insert_size[i];
		     i++) {

			if (tb->lnum[i]) {

				if (tb->L[i]) {
					tb_buffer_sanity_check(tb->tb_sb,
							       tb->L[i],
							       "L", i);
					if (!clear_all_dirty_bits
					    (tb->tb_sb, tb->L[i]))
						locked = tb->L[i];
				}

				if (!locked && tb->FL[i]) {
					tb_buffer_sanity_check(tb->tb_sb,
							       tb->FL[i],
							       "FL", i);
					if (!clear_all_dirty_bits
					    (tb->tb_sb, tb->FL[i]))
						locked = tb->FL[i];
				}

				if (!locked && tb->CFL[i]) {
					tb_buffer_sanity_check(tb->tb_sb,
							       tb->CFL[i],
							       "CFL", i);
					if (!clear_all_dirty_bits
					    (tb->tb_sb, tb->CFL[i]))
						locked = tb->CFL[i];
				}

			}

			if (!locked && (tb->rnum[i])) {

				if (tb->R[i]) {
					tb_buffer_sanity_check(tb->tb_sb,
							       tb->R[i],
							       "R", i);
					if (!clear_all_dirty_bits
					    (tb->tb_sb, tb->R[i]))
						locked = tb->R[i];
				}

				if (!locked && tb->FR[i]) {
					tb_buffer_sanity_check(tb->tb_sb,
							       tb->FR[i],
							       "FR", i);
					if (!clear_all_dirty_bits
					    (tb->tb_sb, tb->FR[i]))
						locked = tb->FR[i];
				}

				if (!locked && tb->CFR[i]) {
					tb_buffer_sanity_check(tb->tb_sb,
							       tb->CFR[i],
							       "CFR", i);
					if (!clear_all_dirty_bits
					    (tb->tb_sb, tb->CFR[i]))
						locked = tb->CFR[i];
				}
			}
		}
		/* as far as I can tell, this is not required.  The FEB list seems
		 ** to be full of newly allocated nodes, which will never be locked,
		 ** dirty, or anything else.
		 ** To be safe, I'm putting in the checks and waits in.  For the moment,
		 ** they are needed to keep the code in journal.c from complaining
		 ** about the buffer.  That code is inside CONFIG_REISERFS_CHECK as well.
		 ** --clm
		 */
		for (i = 0; !locked && i < MAX_FEB_SIZE; i++) {
			if (tb->FEB[i]) {
				if (!clear_all_dirty_bits
				    (tb->tb_sb, tb->FEB[i]))
					locked = tb->FEB[i];
			}
		}

		if (locked) {
			int depth;
#ifdef CONFIG_REISERFS_CHECK
			repeat_counter++;
			if ((repeat_counter % 10000) == 0) {
				reiserfs_warning(tb->tb_sb, "reiserfs-8200",
						 "too many iterations waiting "
						 "for buffer to unlock "
						 "(%b)", locked);

				/* Don't loop forever.  Try to recover from possible error. */

				return (FILESYSTEM_CHANGED_TB(tb)) ?
				    REPEAT_SEARCH : CARRY_ON;
			}
#endif
			depth = reiserfs_write_unlock_nested(tb->tb_sb);
			__wait_on_buffer(locked);
			reiserfs_write_lock_nested(tb->tb_sb, depth);
			if (FILESYSTEM_CHANGED_TB(tb))
				return REPEAT_SEARCH;
		}

	} while (locked);

	return CARRY_ON;
}

/* Prepare for balancing, that is
 *	get all necessary parents, and neighbors;
 *	analyze what and where should be moved;
 *	get sufficient number of new nodes;
 * Balancing will start only after all resources will be collected at a time.
 *
 * When ported to SMP kernels, only at the last moment after all needed nodes
 * are collected in cache, will the resources be locked using the usual
 * textbook ordered lock acquisition algorithms.  Note that ensuring that
 * this code neither write locks what it does not need to write lock nor locks out of order
 * will be a pain in the butt that could have been avoided.  Grumble grumble. -Hans
 *
 * fix is meant in the sense of render unchanging
 *
 * Latency might be improved by first gathering a list of what buffers are needed
 * and then getting as many of them in parallel as possible? -Hans
 *
 * Parameters:
 *	op_mode	i - insert, d - delete, c - cut (truncate), p - paste (append)
 *	tb	tree_balance structure;
 *	inum	item number in S[h];
 *      pos_in_item - comment this if you can
 *      ins_ih	item head of item being inserted
 *	data	inserted item or data to be pasted
 * Returns:	1 - schedule occurred while the function worked;
 *	        0 - schedule didn't occur while the function worked;
 *             -1 - if no_disk_space
 */

int fix_nodes(int op_mode, struct tree_balance *tb,
	      struct item_head *ins_ih, const void *data)
{
	int ret, h, item_num = PATH_LAST_POSITION(tb->tb_path);
	int pos_in_item;

	/* we set wait_tb_buffers_run when we have to restore any dirty bits cleared
	 ** during wait_tb_buffers_run
	 */
	int wait_tb_buffers_run = 0;
	struct buffer_head *tbS0 = PATH_PLAST_BUFFER(tb->tb_path);

	++REISERFS_SB(tb->tb_sb)->s_fix_nodes;

	pos_in_item = tb->tb_path->pos_in_item;

	tb->fs_gen = get_generation(tb->tb_sb);

	/* we prepare and log the super here so it will already be in the
	 ** transaction when do_balance needs to change it.
	 ** This way do_balance won't have to schedule when trying to prepare
	 ** the super for logging
	 */
	reiserfs_prepare_for_journal(tb->tb_sb,
				     SB_BUFFER_WITH_SB(tb->tb_sb), 1);
	journal_mark_dirty(tb->transaction_handle, tb->tb_sb,
			   SB_BUFFER_WITH_SB(tb->tb_sb));
	if (FILESYSTEM_CHANGED_TB(tb))
		return REPEAT_SEARCH;

	/* if it possible in indirect_to_direct conversion */
	if (buffer_locked(tbS0)) {
		int depth = reiserfs_write_unlock_nested(tb->tb_sb);
		__wait_on_buffer(tbS0);
		reiserfs_write_lock_nested(tb->tb_sb, depth);
		if (FILESYSTEM_CHANGED_TB(tb))
			return REPEAT_SEARCH;
	}
#ifdef CONFIG_REISERFS_CHECK
	if (REISERFS_SB(tb->tb_sb)->cur_tb) {
		print_cur_tb("fix_nodes");
		reiserfs_panic(tb->tb_sb, "PAP-8305",
			       "there is pending do_balance");
	}

	if (!buffer_uptodate(tbS0) || !B_IS_IN_TREE(tbS0))
		reiserfs_panic(tb->tb_sb, "PAP-8320", "S[0] (%b %z) is "
			       "not uptodate at the beginning of fix_nodes "
			       "or not in tree (mode %c)",
			       tbS0, tbS0, op_mode);

	/* Check parameters. */
	switch (op_mode) {
	case M_INSERT:
		if (item_num <= 0 || item_num > B_NR_ITEMS(tbS0))
			reiserfs_panic(tb->tb_sb, "PAP-8330", "Incorrect "
				       "item number %d (in S0 - %d) in case "
				       "of insert", item_num,
				       B_NR_ITEMS(tbS0));
		break;
	case M_PASTE:
	case M_DELETE:
	case M_CUT:
		if (item_num < 0 || item_num >= B_NR_ITEMS(tbS0)) {
			print_block(tbS0, 0, -1, -1);
			reiserfs_panic(tb->tb_sb, "PAP-8335", "Incorrect "
				       "item number(%d); mode = %c "
				       "insert_size = %d",
				       item_num, op_mode,
				       tb->insert_size[0]);
		}
		break;
	default:
		reiserfs_panic(tb->tb_sb, "PAP-8340", "Incorrect mode "
			       "of operation");
	}
#endif

	if (get_mem_for_virtual_node(tb) == REPEAT_SEARCH)
		// FIXME: maybe -ENOMEM when tb->vn_buf == 0? Now just repeat
		return REPEAT_SEARCH;

	/* Starting from the leaf level; for all levels h of the tree. */
	for (h = 0; h < MAX_HEIGHT && tb->insert_size[h]; h++) {
		ret = get_direct_parent(tb, h);
		if (ret != CARRY_ON)
			goto repeat;

		ret = check_balance(op_mode, tb, h, item_num,
				    pos_in_item, ins_ih, data);
		if (ret != CARRY_ON) {
			if (ret == NO_BALANCING_NEEDED) {
				/* No balancing for higher levels needed. */
				ret = get_neighbors(tb, h);
				if (ret != CARRY_ON)
					goto repeat;
				if (h != MAX_HEIGHT - 1)
					tb->insert_size[h + 1] = 0;
				/* ok, analysis and resource gathering are complete */
				break;
			}
			goto repeat;
		}

		ret = get_neighbors(tb, h);
		if (ret != CARRY_ON)
			goto repeat;

		/* No disk space, or schedule occurred and analysis may be
		 * invalid and needs to be redone. */
		ret = get_empty_nodes(tb, h);
		if (ret != CARRY_ON)
			goto repeat;

		if (!PATH_H_PBUFFER(tb->tb_path, h)) {
			/* We have a positive insert size but no nodes exist on this
			   level, this means that we are creating a new root. */

			RFALSE(tb->blknum[h] != 1,
			       "PAP-8350: creating new empty root");

			if (h < MAX_HEIGHT - 1)
				tb->insert_size[h + 1] = 0;
		} else if (!PATH_H_PBUFFER(tb->tb_path, h + 1)) {
			if (tb->blknum[h] > 1) {
				/* The tree needs to be grown, so this node S[h]
				   which is the root node is split into two nodes,
				   and a new node (S[h+1]) will be created to
				   become the root node.  */

				RFALSE(h == MAX_HEIGHT - 1,
				       "PAP-8355: attempt to create too high of a tree");

				tb->insert_size[h + 1] =
				    (DC_SIZE +
				     KEY_SIZE) * (tb->blknum[h] - 1) +
				    DC_SIZE;
			} else if (h < MAX_HEIGHT - 1)
				tb->insert_size[h + 1] = 0;
		} else
			tb->insert_size[h + 1] =
			    (DC_SIZE + KEY_SIZE) * (tb->blknum[h] - 1);
	}

	ret = wait_tb_buffers_until_unlocked(tb);
	if (ret == CARRY_ON) {
		if (FILESYSTEM_CHANGED_TB(tb)) {
			wait_tb_buffers_run = 1;
			ret = REPEAT_SEARCH;
			goto repeat;
		} else {
			return CARRY_ON;
		}
	} else {
		wait_tb_buffers_run = 1;
		goto repeat;
	}

      repeat:
	// fix_nodes was unable to perform its calculation due to
	// filesystem got changed under us, lack of free disk space or i/o
	// failure. If the first is the case - the search will be
	// repeated. For now - free all resources acquired so far except
	// for the new allocated nodes
	{
		int i;

		/* Release path buffers. */
		if (wait_tb_buffers_run) {
			pathrelse_and_restore(tb->tb_sb, tb->tb_path);
		} else {
			pathrelse(tb->tb_path);
		}
		/* brelse all resources collected for balancing */
		for (i = 0; i < MAX_HEIGHT; i++) {
			if (wait_tb_buffers_run) {
				reiserfs_restore_prepared_buffer(tb->tb_sb,
								 tb->L[i]);
				reiserfs_restore_prepared_buffer(tb->tb_sb,
								 tb->R[i]);
				reiserfs_restore_prepared_buffer(tb->tb_sb,
								 tb->FL[i]);
				reiserfs_restore_prepared_buffer(tb->tb_sb,
								 tb->FR[i]);
				reiserfs_restore_prepared_buffer(tb->tb_sb,
								 tb->
								 CFL[i]);
				reiserfs_restore_prepared_buffer(tb->tb_sb,
								 tb->
								 CFR[i]);
			}

			brelse(tb->L[i]);
			brelse(tb->R[i]);
			brelse(tb->FL[i]);
			brelse(tb->FR[i]);
			brelse(tb->CFL[i]);
			brelse(tb->CFR[i]);

			tb->L[i] = NULL;
			tb->R[i] = NULL;
			tb->FL[i] = NULL;
			tb->FR[i] = NULL;
			tb->CFL[i] = NULL;
			tb->CFR[i] = NULL;
		}

		if (wait_tb_buffers_run) {
			for (i = 0; i < MAX_FEB_SIZE; i++) {
				if (tb->FEB[i])
					reiserfs_restore_prepared_buffer
					    (tb->tb_sb, tb->FEB[i]);
			}
		}
		return ret;
	}

}

/* Anatoly will probably forgive me renaming tb to tb. I just
   wanted to make lines shorter */
void unfix_nodes(struct tree_balance *tb)
{
	int i;

	/* Release path buffers. */
	pathrelse_and_restore(tb->tb_sb, tb->tb_path);

	/* brelse all resources collected for balancing */
	for (i = 0; i < MAX_HEIGHT; i++) {
		reiserfs_restore_prepared_buffer(tb->tb_sb, tb->L[i]);
		reiserfs_restore_prepared_buffer(tb->tb_sb, tb->R[i]);
		reiserfs_restore_prepared_buffer(tb->tb_sb, tb->FL[i]);
		reiserfs_restore_prepared_buffer(tb->tb_sb, tb->FR[i]);
		reiserfs_restore_prepared_buffer(tb->tb_sb, tb->CFL[i]);
		reiserfs_restore_prepared_buffer(tb->tb_sb, tb->CFR[i]);

		brelse(tb->L[i]);
		brelse(tb->R[i]);
		brelse(tb->FL[i]);
		brelse(tb->FR[i]);
		brelse(tb->CFL[i]);
		brelse(tb->CFR[i]);
	}

	/* deal with list of allocated (used and unused) nodes */
	for (i = 0; i < MAX_FEB_SIZE; i++) {
		if (tb->FEB[i]) {
			b_blocknr_t blocknr = tb->FEB[i]->b_blocknr;
			/* de-allocated block which was not used by balancing and
			   bforget about buffer for it */
			brelse(tb->FEB[i]);
			reiserfs_free_block(tb->transaction_handle, NULL,
					    blocknr, 0);
		}
		if (tb->used[i]) {
			/* release used as new nodes including a new root */
			brelse(tb->used[i]);
		}
	}

	kfree(tb->vn_buf);

}