fs/sysv/ialloc.c

   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 (card@masi.ibp.fr)
   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 "sysv.h"
  29
  30 /* We don't trust the value of
  31    sb->sv_sbd2->s_tinode = *sb->sv_sb_total_free_inodes
  32    but we nevertheless keep it up to date. */
  33
  34 /* An inode on disk is considered free if both i_mode == 0 and i_nlink == 0. */
  35
  36 /* return &sb->sv_sb_fic_inodes[i] = &sbd->s_inode[i]; */
  37 static inline sysv_ino_t *
  38 sv_sb_fic_inode(struct super_block * sb, unsigned int i)
  39 {
  40         struct sysv_sb_info *sbi = SYSV_SB(sb);
  41
  42         if (sbi->s_bh1 == sbi->s_bh2)
  43                 return &sbi->s_sb_fic_inodes[i];
  44         else {
  45                 /* 512 byte Xenix FS */
  46                 unsigned int offset = offsetof(struct xenix_super_block, s_inode[i]);
  47                 if (offset < 512)
  48                         return (sysv_ino_t*)(sbi->s_sbd1 + offset);
  49                 else
  50                         return (sysv_ino_t*)(sbi->s_sbd2 + offset);
  51         }
  52 }
  53
  54 struct sysv_inode *
  55 sysv_raw_inode(struct super_block *sb, unsigned ino, struct buffer_head **bh)
  56 {
  57         struct sysv_sb_info *sbi = SYSV_SB(sb);
  58         struct sysv_inode *res;
  59         int block = sbi->s_firstinodezone + sbi->s_block_base;
  60
  61         block += (ino-1) >> sbi->s_inodes_per_block_bits;
  62         *bh = sb_bread(sb, block);
  63         if (!*bh)
  64                 return NULL;
  65         res = (struct sysv_inode *)(*bh)->b_data;
  66         return res + ((ino-1) & sbi->s_inodes_per_block_1);
  67 }
  68
  69 static int refill_free_cache(struct super_block *sb)
  70 {
  71         struct sysv_sb_info *sbi = SYSV_SB(sb);
  72         struct buffer_head * bh;
  73         struct sysv_inode * raw_inode;
  74         int i = 0, ino;
  75
  76         ino = SYSV_ROOT_INO+1;
  77         raw_inode = sysv_raw_inode(sb, ino, &bh);
  78         if (!raw_inode)
  79                 goto out;
  80         while (ino <= sbi->s_ninodes) {
  81                 if (raw_inode->i_mode == 0 && raw_inode->i_nlink == 0) {
  82                         *sv_sb_fic_inode(sb,i++) = cpu_to_fs16(SYSV_SB(sb), ino);
  83                         if (i == sbi->s_fic_size)
  84                                 break;
  85                 }
  86                 if ((ino++ & sbi->s_inodes_per_block_1) == 0) {
  87                         brelse(bh);
  88                         raw_inode = sysv_raw_inode(sb, ino, &bh);
  89                         if (!raw_inode)
  90                                 goto out;
  91                 } else
  92                         raw_inode++;
  93         }
  94         brelse(bh);
  95 out:
  96         return i;
  97 }
  98
  99 void sysv_free_inode(struct inode * inode)
 100 {
 101         struct super_block *sb = inode->i_sb;
 102         struct sysv_sb_info *sbi = SYSV_SB(sb);
 103         unsigned int ino;
 104         struct buffer_head * bh;
 105         struct sysv_inode * raw_inode;
 106         unsigned count;
 107
 108         sb = inode->i_sb;
 109         ino = inode->i_ino;
 110         if (ino <= SYSV_ROOT_INO || ino > sbi->s_ninodes) {
 111                 printk("sysv_free_inode: inode 0,1,2 or nonexistent inode\n");
 112                 return;
 113         }
 114         raw_inode = sysv_raw_inode(sb, ino, &bh);
 115         clear_inode(inode);
 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         lock_super(sb);
 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         unlock_super(sb);
 132         brelse(bh);
 133 }
 134
 135 struct inode * sysv_new_inode(const struct inode * dir, mode_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
 143         inode = new_inode(sb);
 144         if (!inode)
 145                 return ERR_PTR(-ENOMEM);
 146
 147         lock_super(sb);
 148         count = fs16_to_cpu(sbi, *sbi->s_sb_fic_count);
 149         if (count == 0 || (*sv_sb_fic_inode(sb,count-1) == 0)) {
 150                 count = refill_free_cache(sb);
 151                 if (count == 0) {
 152                         iput(inode);
 153                         unlock_super(sb);
 154                         return ERR_PTR(-ENOSPC);
 155                 }
 156         }
 157         /* Now count > 0. */
 158         ino = *sv_sb_fic_inode(sb,--count);
 159         *sbi->s_sb_fic_count = cpu_to_fs16(sbi, count);
 160         fs16_add(sbi, sbi->s_sb_total_free_inodes, -1);
 161         dirty_sb(sb);
 162         inode_init_owner(inode, dir, mode);
 163         inode->i_ino = fs16_to_cpu(sbi, ino);
 164         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME_SEC;
 165         inode->i_blocks = 0;
 166         memset(SYSV_I(inode)->i_data, 0, sizeof(SYSV_I(inode)->i_data));
 167         SYSV_I(inode)->i_dir_start_lookup = 0;
 168         insert_inode_hash(inode);
 169         mark_inode_dirty(inode);
 170
 171         sysv_write_inode(inode, 0);     /* ensure inode not allocated again */
 172         mark_inode_dirty(inode);        /* cleared by sysv_write_inode() */
 173         /* That's it. */
 174         unlock_super(sb);
 175         return inode;
 176 }
 177
 178 unsigned long sysv_count_free_inodes(struct super_block * sb)
 179 {
 180         struct sysv_sb_info *sbi = SYSV_SB(sb);
 181         struct buffer_head * bh;
 182         struct sysv_inode * raw_inode;
 183         int ino, count, sb_count;
 184
 185         lock_super(sb);
 186
 187         sb_count = fs16_to_cpu(sbi, *sbi->s_sb_total_free_inodes);
 188
 189         if (0)
 190                 goto trust_sb;
 191
 192         /* this causes a lot of disk traffic ... */
 193         count = 0;
 194         ino = SYSV_ROOT_INO+1;
 195         raw_inode = sysv_raw_inode(sb, ino, &bh);
 196         if (!raw_inode)
 197                 goto Eio;
 198         while (ino <= sbi->s_ninodes) {
 199                 if (raw_inode->i_mode == 0 && raw_inode->i_nlink == 0)
 200                         count++;
 201                 if ((ino++ & sbi->s_inodes_per_block_1) == 0) {
 202                         brelse(bh);
 203                         raw_inode = sysv_raw_inode(sb, ino, &bh);
 204                         if (!raw_inode)
 205                                 goto Eio;
 206                 } else
 207                         raw_inode++;
 208         }
 209         brelse(bh);
 210         if (count != sb_count)
 211                 goto Einval;
 212 out:
 213         unlock_super(sb);
 214         return count;
 215
 216 Einval:
 217         printk("sysv_count_free_inodes: "
 218                 "free inode count was %d, correcting to %d\n",
 219                 sb_count, count);
 220         if (!(sb->s_flags & MS_RDONLY)) {
 221                 *sbi->s_sb_total_free_inodes = cpu_to_fs16(SYSV_SB(sb), count);
 222                 dirty_sb(sb);
 223         }
 224         goto out;
 225
 226 Eio:
 227         printk("sysv_count_free_inodes: unable to read inode table\n");
 228 trust_sb:
 229         count = sb_count;
 230         goto out;
 231 }