1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * linux/fs/sysv/ialloc.c
4 *
5 * minix/bitmap.c
6 * Copyright (C) 1991, 1992 Linus Torvalds
7 *
8 * ext/freelists.c
9 * Copyright (C) 1992 Remy Card (card@masi.ibp.fr)
10 *
11 * xenix/alloc.c
12 * Copyright (C) 1992 Doug Evans
13 *
14 * coh/alloc.c
15 * Copyright (C) 1993 Pascal Haible, Bruno Haible
16 *
17 * sysv/ialloc.c
18 * Copyright (C) 1993 Bruno Haible
19 *
20 * This file contains code for allocating/freeing inodes.
21 */
22
23 #include <linux/kernel.h>
24 #include <linux/stddef.h>
25 #include <linux/sched.h>
26 #include <linux/stat.h>
27 #include <linux/string.h>
28 #include <linux/buffer_head.h>
29 #include <linux/writeback.h>
30 #include "sysv.h"
31
32 /* We don't trust the value of
33 sb->sv_sbd2->s_tinode = *sb->sv_sb_total_free_inodes
34 but we nevertheless keep it up to date. */
35
36 /* An inode on disk is considered free if both i_mode == 0 and i_nlink == 0. */
37
38 /* return &sb->sv_sb_fic_inodes[i] = &sbd->s_inode[i]; */
39 static inline sysv_ino_t *
40 sv_sb_fic_inode(struct super_block * sb, unsigned int i)
41 {
42 struct sysv_sb_info *sbi = SYSV_SB(sb);
43
44 if (sbi->s_bh1 == sbi->s_bh2)
45 return &sbi->s_sb_fic_inodes[i];
46 else {
47 /* 512 byte Xenix FS */
48 unsigned int offset = offsetof(struct xenix_super_block, s_inode[i]);
49 if (offset < 512)
50 return (sysv_ino_t*)(sbi->s_sbd1 + offset);
51 else
52 return (sysv_ino_t*)(sbi->s_sbd2 + offset);
53 }
54 }
55
56 struct sysv_inode *
57 sysv_raw_inode(struct super_block *sb, unsigned ino, struct buffer_head **bh)
58 {
59 struct sysv_sb_info *sbi = SYSV_SB(sb);
60 struct sysv_inode *res;
61 int block = sbi->s_firstinodezone + sbi->s_block_base;
62
63 block += (ino-1) >> sbi->s_inodes_per_block_bits;
64 *bh = sb_bread(sb, block);
65 if (!*bh)
66 return NULL;
67 res = (struct sysv_inode *)(*bh)->b_data;
68 return res + ((ino-1) & sbi->s_inodes_per_block_1);
69 }
70
71 static int refill_free_cache(struct super_block *sb)
72 {
73 struct sysv_sb_info *sbi = SYSV_SB(sb);
74 struct buffer_head * bh;
75 struct sysv_inode * raw_inode;
76 int i = 0, ino;
77
78 ino = SYSV_ROOT_INO+1;
79 raw_inode = sysv_raw_inode(sb, ino, &bh);
80 if (!raw_inode)
81 goto out;
82 while (ino <= sbi->s_ninodes) {
83 if (raw_inode->i_mode == 0 && raw_inode->i_nlink == 0) {
84 *sv_sb_fic_inode(sb,i++) = cpu_to_fs16(SYSV_SB(sb), ino);
85 if (i == sbi->s_fic_size)
86 break;
87 }
88 if ((ino++ & sbi->s_inodes_per_block_1) == 0) {
89 brelse(bh);
90 raw_inode = sysv_raw_inode(sb, ino, &bh);
91 if (!raw_inode)
92 goto out;
93 } else
94 raw_inode++;
95 }
96 brelse(bh);
97 out:
98 return i;
99 }
100
101 void sysv_free_inode(struct inode * inode)
102 {
103 struct super_block *sb = inode->i_sb;
104 struct sysv_sb_info *sbi = SYSV_SB(sb);
105 unsigned int ino;
106 struct buffer_head * bh;
107 struct sysv_inode * raw_inode;
108 unsigned count;
109
110 sb = inode->i_sb;
111 ino = inode->i_ino;
112 if (ino <= SYSV_ROOT_INO || ino > sbi->s_ninodes) {
113 printk("sysv_free_inode: inode 0,1,2 or nonexistent inode\n");
114 return;
115 }
116 raw_inode = sysv_raw_inode(sb, ino, &bh);
117 if (!raw_inode) {
118 printk("sysv_free_inode: unable to read inode block on device "
119 "%s\n", inode->i_sb->s_id);
120 return;
121 }
122 mutex_lock(&sbi->s_lock);
123 count = fs16_to_cpu(sbi, *sbi->s_sb_fic_count);
124 if (count < sbi->s_fic_size) {
125 *sv_sb_fic_inode(sb,count++) = cpu_to_fs16(sbi, ino);
126 *sbi->s_sb_fic_count = cpu_to_fs16(sbi, count);
127 }
128 fs16_add(sbi, sbi->s_sb_total_free_inodes, 1);
129 dirty_sb(sb);
130 memset(raw_inode, 0, sizeof(struct sysv_inode));
131 mark_buffer_dirty(bh);
132 mutex_unlock(&sbi->s_lock);
133 brelse(bh);
134 }
135
136 struct inode * sysv_new_inode(const struct inode * dir, umode_t mode)
137 {
138 struct super_block *sb = dir->i_sb;
139 struct sysv_sb_info *sbi = SYSV_SB(sb);
140 struct inode *inode;
141 sysv_ino_t ino;
142 unsigned count;
143 struct writeback_control wbc = {
144 .sync_mode = WB_SYNC_NONE
145 };
146
147 inode = new_inode(sb);
148 if (!inode)
149 return ERR_PTR(-ENOMEM);
150
151 mutex_lock(&sbi->s_lock);
152 count = fs16_to_cpu(sbi, *sbi->s_sb_fic_count);
153 if (count == 0 || (*sv_sb_fic_inode(sb,count-1) == 0)) {
154 count = refill_free_cache(sb);
155 if (count == 0) {
156 iput(inode);
157 mutex_unlock(&sbi->s_lock);
158 return ERR_PTR(-ENOSPC);
159 }
160 }
161 /* Now count > 0. */
162 ino = *sv_sb_fic_inode(sb,--count);
163 *sbi->s_sb_fic_count = cpu_to_fs16(sbi, count);
164 fs16_add(sbi, sbi->s_sb_total_free_inodes, -1);
165 dirty_sb(sb);
166 inode_init_owner(&nop_mnt_idmap, inode, dir, mode);
167 inode->i_ino = fs16_to_cpu(sbi, ino);
168 simple_inode_init_ts(inode);
169 inode->i_blocks = 0;
170 memset(SYSV_I(inode)->i_data, 0, sizeof(SYSV_I(inode)->i_data));
171 SYSV_I(inode)->i_dir_start_lookup = 0;
172 insert_inode_hash(inode);
173 mark_inode_dirty(inode);
174
175 sysv_write_inode(inode, &wbc); /* ensure inode not allocated again */
176 mark_inode_dirty(inode); /* cleared by sysv_write_inode() */
177 /* That's it. */
178 mutex_unlock(&sbi->s_lock);
179 return inode;
180 }
181
182 unsigned long sysv_count_free_inodes(struct super_block * sb)
183 {
184 struct sysv_sb_info *sbi = SYSV_SB(sb);
185 struct buffer_head * bh;
186 struct sysv_inode * raw_inode;
187 int ino, count, sb_count;
188
189 mutex_lock(&sbi->s_lock);
190
191 sb_count = fs16_to_cpu(sbi, *sbi->s_sb_total_free_inodes);
192
193 if (0)
194 goto trust_sb;
195
196 /* this causes a lot of disk traffic ... */
197 count = 0;
198 ino = SYSV_ROOT_INO+1;
199 raw_inode = sysv_raw_inode(sb, ino, &bh);
200 if (!raw_inode)
201 goto Eio;
202 while (ino <= sbi->s_ninodes) {
203 if (raw_inode->i_mode == 0 && raw_inode->i_nlink == 0)
204 count++;
205 if ((ino++ & sbi->s_inodes_per_block_1) == 0) {
206 brelse(bh);
207 raw_inode = sysv_raw_inode(sb, ino, &bh);
208 if (!raw_inode)
209 goto Eio;
210 } else
211 raw_inode++;
212 }
213 brelse(bh);
214 if (count != sb_count)
215 goto Einval;
216 out:
217 mutex_unlock(&sbi->s_lock);
218 return count;
219
220 Einval:
221 printk("sysv_count_free_inodes: "
222 "free inode count was %d, correcting to %d\n",
223 sb_count, count);
224 if (!sb_rdonly(sb)) {
225 *sbi->s_sb_total_free_inodes = cpu_to_fs16(SYSV_SB(sb), count);
226 dirty_sb(sb);
227 }
228 goto out;
229
230 Eio:
231 printk("sysv_count_free_inodes: unable to read inode table\n");
232 trust_sb:
233 count = sb_count;
234 goto out;
235 }
236
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