fs/ufs/cylinder.c

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