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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  */
 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 }
202 

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