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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  */
  28 static 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
  71 failed:
  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  */
  82 void 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  */
 126 struct 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 }