fs/sysv/ialloc.c

   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(inode, dir, mode);
 167         inode->i_ino = fs16_to_cpu(sbi, ino);
 168         inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(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 }