linux/fs/ufs/cylinder.c
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   1/*
   2 *  linux/fs/ufs/cylinder.c
   3 *
   4 * Copyright (C) 1998
   5 * Daniel Pirkl <daniel.pirkl@email.cz>
   6 * Charles University, Faculty of Mathematics and Physics
   7 *
   8 *  ext2 - inode (block) bitmap caching inspired
   9 */
  10
  11#include <linux/fs.h>
  12#include <linux/time.h>
  13#include <linux/stat.h>
  14#include <linux/string.h>
  15#include <linux/bitops.h>
  16
  17#include <asm/byteorder.h>
  18
  19#include "ufs_fs.h"
  20#include "ufs.h"
  21#include "swab.h"
  22#include "util.h"
  23
  24/*
  25 * Read cylinder group into cache. The memory space for ufs_cg_private_info
  26 * structure is already allocated during ufs_read_super.
  27 */
  28static void ufs_read_cylinder (struct super_block * sb,
  29        unsigned cgno, unsigned bitmap_nr)
  30{
  31        struct ufs_sb_info * sbi = UFS_SB(sb);
  32        struct ufs_sb_private_info * uspi;
  33        struct ufs_cg_private_info * ucpi;
  34        struct ufs_cylinder_group * ucg;
  35        unsigned i, j;
  36
  37        UFSD("ENTER, cgno %u, bitmap_nr %u\n", cgno, bitmap_nr);
  38        uspi = sbi->s_uspi;
  39        ucpi = sbi->s_ucpi[bitmap_nr];
  40        ucg = (struct ufs_cylinder_group *)sbi->s_ucg[cgno]->b_data;
  41
  42        UCPI_UBH(ucpi)->fragment = ufs_cgcmin(cgno);
  43        UCPI_UBH(ucpi)->count = uspi->s_cgsize >> sb->s_blocksize_bits;
  44        /*
  45         * We have already the first fragment of cylinder group block in buffer
  46         */
  47        UCPI_UBH(ucpi)->bh[0] = sbi->s_ucg[cgno];
  48        for (i = 1; i < UCPI_UBH(ucpi)->count; i++)
  49                if (!(UCPI_UBH(ucpi)->bh[i] = sb_bread(sb, UCPI_UBH(ucpi)->fragment + i)))
  50                        goto failed;
  51        sbi->s_cgno[bitmap_nr] = cgno;
  52                        
  53        ucpi->c_cgx     = fs32_to_cpu(sb, ucg->cg_cgx);
  54        ucpi->c_ncyl    = fs16_to_cpu(sb, ucg->cg_ncyl);
  55        ucpi->c_niblk   = fs16_to_cpu(sb, ucg->cg_niblk);
  56        ucpi->c_ndblk   = fs32_to_cpu(sb, ucg->cg_ndblk);
  57        ucpi->c_rotor   = fs32_to_cpu(sb, ucg->cg_rotor);
  58        ucpi->c_frotor  = fs32_to_cpu(sb, ucg->cg_frotor);
  59        ucpi->c_irotor  = fs32_to_cpu(sb, ucg->cg_irotor);
  60        ucpi->c_btotoff = fs32_to_cpu(sb, ucg->cg_btotoff);
  61        ucpi->c_boff    = fs32_to_cpu(sb, ucg->cg_boff);
  62        ucpi->c_iusedoff = fs32_to_cpu(sb, ucg->cg_iusedoff);
  63        ucpi->c_freeoff = fs32_to_cpu(sb, ucg->cg_freeoff);
  64        ucpi->c_nextfreeoff = fs32_to_cpu(sb, ucg->cg_nextfreeoff);
  65        ucpi->c_clustersumoff = fs32_to_cpu(sb, ucg->cg_u.cg_44.cg_clustersumoff);
  66        ucpi->c_clusteroff = fs32_to_cpu(sb, ucg->cg_u.cg_44.cg_clusteroff);
  67        ucpi->c_nclusterblks = fs32_to_cpu(sb, ucg->cg_u.cg_44.cg_nclusterblks);
  68        UFSD("EXIT\n");
  69        return; 
  70        
  71failed:
  72        for (j = 1; j < i; j++)
  73                brelse (sbi->s_ucg[j]);
  74        sbi->s_cgno[bitmap_nr] = UFS_CGNO_EMPTY;
  75        ufs_error (sb, "ufs_read_cylinder", "can't read cylinder group block %u", cgno);
  76}
  77
  78/*
  79 * Remove cylinder group from cache, doesn't release memory
  80 * allocated for cylinder group (this is done at ufs_put_super only).
  81 */
  82void ufs_put_cylinder (struct super_block * sb, unsigned bitmap_nr)
  83{
  84        struct ufs_sb_info * sbi = UFS_SB(sb);
  85        struct ufs_sb_private_info * uspi; 
  86        struct ufs_cg_private_info * ucpi;
  87        struct ufs_cylinder_group * ucg;
  88        unsigned i;
  89
  90        UFSD("ENTER, bitmap_nr %u\n", bitmap_nr);
  91
  92        uspi = sbi->s_uspi;
  93        if (sbi->s_cgno[bitmap_nr] == UFS_CGNO_EMPTY) {
  94                UFSD("EXIT\n");
  95                return;
  96        }
  97        ucpi = sbi->s_ucpi[bitmap_nr];
  98        ucg = ubh_get_ucg(UCPI_UBH(ucpi));
  99
 100        if (uspi->s_ncg > UFS_MAX_GROUP_LOADED && bitmap_nr >= sbi->s_cg_loaded) {
 101                ufs_panic (sb, "ufs_put_cylinder", "internal error");
 102                return;
 103        }
 104        /*
 105         * rotor is not so important data, so we put it to disk 
 106         * at the end of working with cylinder
 107         */
 108        ucg->cg_rotor = cpu_to_fs32(sb, ucpi->c_rotor);
 109        ucg->cg_frotor = cpu_to_fs32(sb, ucpi->c_frotor);
 110        ucg->cg_irotor = cpu_to_fs32(sb, ucpi->c_irotor);
 111        ubh_mark_buffer_dirty (UCPI_UBH(ucpi));
 112        for (i = 1; i < UCPI_UBH(ucpi)->count; i++) {
 113                brelse (UCPI_UBH(ucpi)->bh[i]);
 114        }
 115
 116        sbi->s_cgno[bitmap_nr] = UFS_CGNO_EMPTY;
 117        UFSD("EXIT\n");
 118}
 119
 120/*
 121 * Find cylinder group in cache and return it as pointer.
 122 * If cylinder group is not in cache, we will load it from disk.
 123 *
 124 * The cache is managed by LRU algorithm. 
 125 */
 126struct ufs_cg_private_info * ufs_load_cylinder (
 127        struct super_block * sb, unsigned cgno)
 128{
 129        struct ufs_sb_info * sbi = UFS_SB(sb);
 130        struct ufs_sb_private_info * uspi;
 131        struct ufs_cg_private_info * ucpi;
 132        unsigned cg, i, j;
 133
 134        UFSD("ENTER, cgno %u\n", cgno);
 135
 136        uspi = sbi->s_uspi;
 137        if (cgno >= uspi->s_ncg) {
 138                ufs_panic (sb, "ufs_load_cylinder", "internal error, high number of cg");
 139                return NULL;
 140        }
 141        /*
 142         * Cylinder group number cg it in cache and it was last used
 143         */
 144        if (sbi->s_cgno[0] == cgno) {
 145                UFSD("EXIT\n");
 146                return sbi->s_ucpi[0];
 147        }
 148        /*
 149         * Number of cylinder groups is not higher than UFS_MAX_GROUP_LOADED
 150         */
 151        if (uspi->s_ncg <= UFS_MAX_GROUP_LOADED) {
 152                if (sbi->s_cgno[cgno] != UFS_CGNO_EMPTY) {
 153                        if (sbi->s_cgno[cgno] != cgno) {
 154                                ufs_panic (sb, "ufs_load_cylinder", "internal error, wrong number of cg in cache");
 155                                UFSD("EXIT (FAILED)\n");
 156                                return NULL;
 157                        }
 158                        else {
 159                                UFSD("EXIT\n");
 160                                return sbi->s_ucpi[cgno];
 161                        }
 162                } else {
 163                        ufs_read_cylinder (sb, cgno, cgno);
 164                        UFSD("EXIT\n");
 165                        return sbi->s_ucpi[cgno];
 166                }
 167        }
 168        /*
 169         * Cylinder group number cg is in cache but it was not last used, 
 170         * we will move to the first position
 171         */
 172        for (i = 0; i < sbi->s_cg_loaded && sbi->s_cgno[i] != cgno; i++);
 173        if (i < sbi->s_cg_loaded && sbi->s_cgno[i] == cgno) {
 174                cg = sbi->s_cgno[i];
 175                ucpi = sbi->s_ucpi[i];
 176                for (j = i; j > 0; j--) {
 177                        sbi->s_cgno[j] = sbi->s_cgno[j-1];
 178                        sbi->s_ucpi[j] = sbi->s_ucpi[j-1];
 179                }
 180                sbi->s_cgno[0] = cg;
 181                sbi->s_ucpi[0] = ucpi;
 182        /*
 183         * Cylinder group number cg is not in cache, we will read it from disk
 184         * and put it to the first position
 185         */
 186        } else {
 187                if (sbi->s_cg_loaded < UFS_MAX_GROUP_LOADED)
 188                        sbi->s_cg_loaded++;
 189                else
 190                        ufs_put_cylinder (sb, UFS_MAX_GROUP_LOADED-1);
 191                ucpi = sbi->s_ucpi[sbi->s_cg_loaded - 1];
 192                for (j = sbi->s_cg_loaded - 1; j > 0; j--) {
 193                        sbi->s_cgno[j] = sbi->s_cgno[j-1];
 194                        sbi->s_ucpi[j] = sbi->s_ucpi[j-1];
 195                }
 196                sbi->s_ucpi[0] = ucpi;
 197                ufs_read_cylinder (sb, cgno, 0);
 198        }
 199        UFSD("EXIT\n");
 200        return sbi->s_ucpi[0];
 201}
 202
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