projects/linux·blob v4.2 · refs

234 lines · 5.8 KiB

1/*
2 * linux/fs/sysv/ialloc.c
3 *
4 * minix/bitmap.c
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 *
7 * ext/freelists.c
8 * Copyright (C) 1992 Remy Card ([email protected])
9 *
10 * xenix/alloc.c
11 * Copyright (C) 1992 Doug Evans
12 *
13 * coh/alloc.c
14 * Copyright (C) 1993 Pascal Haible, Bruno Haible
15 *
16 * sysv/ialloc.c
17 * Copyright (C) 1993 Bruno Haible
18 *
19 * This file contains code for allocating/freeing inodes.
20 */
21
22#include <linux/kernel.h>
23#include <linux/stddef.h>
24#include <linux/sched.h>
25#include <linux/stat.h>
26#include <linux/string.h>
27#include <linux/buffer_head.h>
28#include <linux/writeback.h>
29#include "sysv.h"
30
31/* We don't trust the value of
32 sb->sv_sbd2->s_tinode = *sb->sv_sb_total_free_inodes
33 but we nevertheless keep it up to date. */
34
35/* An inode on disk is considered free if both i_mode == 0 and i_nlink == 0. */
36
37/* return &sb->sv_sb_fic_inodes[i] = &sbd->s_inode[i]; */
38static inline sysv_ino_t *
39sv_sb_fic_inode(struct super_block * sb, unsigned int i)
40{
41 struct sysv_sb_info *sbi = SYSV_SB(sb);
42
43 if (sbi->s_bh1 == sbi->s_bh2)
44 return &sbi->s_sb_fic_inodes[i];
45 else {
46 /* 512 byte Xenix FS */
47 unsigned int offset = offsetof(struct xenix_super_block, s_inode[i]);
48 if (offset < 512)
49 return (sysv_ino_t*)(sbi->s_sbd1 + offset);
50 else
51 return (sysv_ino_t*)(sbi->s_sbd2 + offset);
52 }
53}
54
55struct sysv_inode *
56sysv_raw_inode(struct super_block *sb, unsigned ino, struct buffer_head **bh)
57{
58 struct sysv_sb_info *sbi = SYSV_SB(sb);
59 struct sysv_inode *res;
60 int block = sbi->s_firstinodezone + sbi->s_block_base;
61
62 block += (ino-1) >> sbi->s_inodes_per_block_bits;
63 *bh = sb_bread(sb, block);
64 if (!*bh)
65 return NULL;
66 res = (struct sysv_inode *)(*bh)->b_data;
67 return res + ((ino-1) & sbi->s_inodes_per_block_1);
68}
69
70static int refill_free_cache(struct super_block *sb)
71{
72 struct sysv_sb_info *sbi = SYSV_SB(sb);
73 struct buffer_head * bh;
74 struct sysv_inode * raw_inode;
75 int i = 0, ino;
76
77 ino = SYSV_ROOT_INO+1;
78 raw_inode = sysv_raw_inode(sb, ino, &bh);
79 if (!raw_inode)
80 goto out;
81 while (ino <= sbi->s_ninodes) {
82 if (raw_inode->i_mode == 0 && raw_inode->i_nlink == 0) {
83 *sv_sb_fic_inode(sb,i++) = cpu_to_fs16(SYSV_SB(sb), ino);
84 if (i == sbi->s_fic_size)
85 break;
86 }
87 if ((ino++ & sbi->s_inodes_per_block_1) == 0) {
88 brelse(bh);
89 raw_inode = sysv_raw_inode(sb, ino, &bh);
90 if (!raw_inode)
91 goto out;
92 } else
93 raw_inode++;
94 }
95 brelse(bh);
96out:
97 return i;
98}
99
100void sysv_free_inode(struct inode * inode)
101{
102 struct super_block *sb = inode->i_sb;
103 struct sysv_sb_info *sbi = SYSV_SB(sb);
104 unsigned int ino;
105 struct buffer_head * bh;
106 struct sysv_inode * raw_inode;
107 unsigned count;
108
109 sb = inode->i_sb;
110 ino = inode->i_ino;
111 if (ino <= SYSV_ROOT_INO || ino > sbi->s_ninodes) {
112 printk("sysv_free_inode: inode 0,1,2 or nonexistent inode\n");
113 return;
114 }
115 raw_inode = sysv_raw_inode(sb, ino, &bh);
116 if (!raw_inode) {
117 printk("sysv_free_inode: unable to read inode block on device "
118 "%s\n", inode->i_sb->s_id);
119 return;
120 }
121 mutex_lock(&sbi->s_lock);
122 count = fs16_to_cpu(sbi, *sbi->s_sb_fic_count);
123 if (count < sbi->s_fic_size) {
124 *sv_sb_fic_inode(sb,count++) = cpu_to_fs16(sbi, ino);
125 *sbi->s_sb_fic_count = cpu_to_fs16(sbi, count);
126 }
127 fs16_add(sbi, sbi->s_sb_total_free_inodes, 1);
128 dirty_sb(sb);
129 memset(raw_inode, 0, sizeof(struct sysv_inode));
130 mark_buffer_dirty(bh);
131 mutex_unlock(&sbi->s_lock);
132 brelse(bh);
133}
134
135struct inode * sysv_new_inode(const struct inode * dir, umode_t mode)
136{
137 struct super_block *sb = dir->i_sb;
138 struct sysv_sb_info *sbi = SYSV_SB(sb);
139 struct inode *inode;
140 sysv_ino_t ino;
141 unsigned count;
142 struct writeback_control wbc = {
143 .sync_mode = WB_SYNC_NONE
144 };
145
146 inode = new_inode(sb);
147 if (!inode)
148 return ERR_PTR(-ENOMEM);
149
150 mutex_lock(&sbi->s_lock);
151 count = fs16_to_cpu(sbi, *sbi->s_sb_fic_count);
152 if (count == 0 || (*sv_sb_fic_inode(sb,count-1) == 0)) {
153 count = refill_free_cache(sb);
154 if (count == 0) {
155 iput(inode);
156 mutex_unlock(&sbi->s_lock);
157 return ERR_PTR(-ENOSPC);
158 }
159 }
160 /* Now count > 0. */
161 ino = *sv_sb_fic_inode(sb,--count);
162 *sbi->s_sb_fic_count = cpu_to_fs16(sbi, count);
163 fs16_add(sbi, sbi->s_sb_total_free_inodes, -1);
164 dirty_sb(sb);
165 inode_init_owner(inode, dir, mode);
166 inode->i_ino = fs16_to_cpu(sbi, ino);
167 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME_SEC;
168 inode->i_blocks = 0;
169 memset(SYSV_I(inode)->i_data, 0, sizeof(SYSV_I(inode)->i_data));
170 SYSV_I(inode)->i_dir_start_lookup = 0;
171 insert_inode_hash(inode);
172 mark_inode_dirty(inode);
173
174 sysv_write_inode(inode, &wbc); /* ensure inode not allocated again */
175 mark_inode_dirty(inode); /* cleared by sysv_write_inode() */
176 /* That's it. */
177 mutex_unlock(&sbi->s_lock);
178 return inode;
179}
180
181unsigned long sysv_count_free_inodes(struct super_block * sb)
182{
183 struct sysv_sb_info *sbi = SYSV_SB(sb);
184 struct buffer_head * bh;
185 struct sysv_inode * raw_inode;
186 int ino, count, sb_count;
187
188 mutex_lock(&sbi->s_lock);
189
190 sb_count = fs16_to_cpu(sbi, *sbi->s_sb_total_free_inodes);
191
192 if (0)
193 goto trust_sb;
194
195 /* this causes a lot of disk traffic ... */
196 count = 0;
197 ino = SYSV_ROOT_INO+1;
198 raw_inode = sysv_raw_inode(sb, ino, &bh);
199 if (!raw_inode)
200 goto Eio;
201 while (ino <= sbi->s_ninodes) {
202 if (raw_inode->i_mode == 0 && raw_inode->i_nlink == 0)
203 count++;
204 if ((ino++ & sbi->s_inodes_per_block_1) == 0) {
205 brelse(bh);
206 raw_inode = sysv_raw_inode(sb, ino, &bh);
207 if (!raw_inode)
208 goto Eio;
209 } else
210 raw_inode++;
211 }
212 brelse(bh);
213 if (count != sb_count)
214 goto Einval;
215out:
216 mutex_unlock(&sbi->s_lock);
217 return count;
218
219Einval:
220 printk("sysv_count_free_inodes: "
221 "free inode count was %d, correcting to %d\n",
222 sb_count, count);
223 if (!(sb->s_flags & MS_RDONLY)) {
224 *sbi->s_sb_total_free_inodes = cpu_to_fs16(SYSV_SB(sb), count);
225 dirty_sb(sb);
226 }
227 goto out;
228
229Eio:
230 printk("sysv_count_free_inodes: unable to read inode table\n");
231trust_sb:
232 count = sb_count;
233 goto out;
234}