release/src-rt-6.x.4708/linux/linux-2.6.36/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 <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]; */
  38 static inline sysv_ino_t *
  39 sv_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
  55 struct sysv_inode *
  56 sysv_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
  70 static 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);
  96 out:
  97         return i;
  98 }
  99
 100 void 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         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         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         lock_super(sb);
 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                         unlock_super(sb);
 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         unlock_super(sb);
 178         return inode;
 179 }
 180
 181 unsigned 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         lock_super(sb);
 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;
 215 out:
 216         unlock_super(sb);
 217         return count;
 218
 219 Einval:
 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
 229 Eio:
 230         printk("sysv_count_free_inodes: unable to read inode table\n");
 231 trust_sb:
 232         count = sb_count;
 233         goto out;
 234 }