[PATCH] ufs: zeroize the rest of block in truncate
[linux-2.6.git] / 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 }