fs/adfs/inode.c

   1 /*
   2  *  linux/fs/adfs/inode.c
   3  *
   4  *  Copyright (C) 1997-1999 Russell King
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10 #include <linux/smp_lock.h>
  11 #include <linux/buffer_head.h>
  12 #include <linux/writeback.h>
  13 #include "adfs.h"
  14
  15 /*
  16  * Lookup/Create a block at offset 'block' into 'inode'.  We currently do
  17  * not support creation of new blocks, so we return -EIO for this case.
  18  */
  19 static int
  20 adfs_get_block(struct inode *inode, sector_t block, struct buffer_head *bh,
  21                int create)
  22 {
  23         if (!create) {
  24                 if (block >= inode->i_blocks)
  25                         goto abort_toobig;
  26
  27                 block = __adfs_block_map(inode->i_sb, inode->i_ino, block);
  28                 if (block)
  29                         map_bh(bh, inode->i_sb, block);
  30                 return 0;
  31         }
  32         /* don't support allocation of blocks yet */
  33         return -EIO;
  34
  35 abort_toobig:
  36         return 0;
  37 }
  38
  39 static int adfs_writepage(struct page *page, struct writeback_control *wbc)
  40 {
  41         return block_write_full_page(page, adfs_get_block, wbc);
  42 }
  43
  44 static int adfs_readpage(struct file *file, struct page *page)
  45 {
  46         return block_read_full_page(page, adfs_get_block);
  47 }
  48
  49 static int adfs_write_begin(struct file *file, struct address_space *mapping,
  50                         loff_t pos, unsigned len, unsigned flags,
  51                         struct page **pagep, void **fsdata)
  52 {
  53         *pagep = NULL;
  54         return cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
  55                                 adfs_get_block,
  56                                 &ADFS_I(mapping->host)->mmu_private);
  57 }
  58
  59 static sector_t _adfs_bmap(struct address_space *mapping, sector_t block)
  60 {
  61         return generic_block_bmap(mapping, block, adfs_get_block);
  62 }
  63
  64 static const struct address_space_operations adfs_aops = {
  65         .readpage       = adfs_readpage,
  66         .writepage      = adfs_writepage,
  67         .sync_page      = block_sync_page,
  68         .write_begin    = adfs_write_begin,
  69         .write_end      = generic_write_end,
  70         .bmap           = _adfs_bmap
  71 };
  72
  73 static inline unsigned int
  74 adfs_filetype(struct inode *inode)
  75 {
  76         unsigned int type;
  77
  78         if (ADFS_I(inode)->stamped)
  79                 type = (ADFS_I(inode)->loadaddr >> 8) & 0xfff;
  80         else
  81                 type = (unsigned int) -1;
  82
  83         return type;
  84 }
  85
  86 /*
  87  * Convert ADFS attributes and filetype to Linux permission.
  88  */
  89 static umode_t
  90 adfs_atts2mode(struct super_block *sb, struct inode *inode)
  91 {
  92         unsigned int filetype, attr = ADFS_I(inode)->attr;
  93         umode_t mode, rmask;
  94         struct adfs_sb_info *asb = ADFS_SB(sb);
  95
  96         if (attr & ADFS_NDA_DIRECTORY) {
  97                 mode = S_IRUGO & asb->s_owner_mask;
  98                 return S_IFDIR | S_IXUGO | mode;
  99         }
 100
 101         filetype = adfs_filetype(inode);
 102
 103         switch (filetype) {
 104         case 0xfc0:     /* LinkFS */
 105                 return S_IFLNK|S_IRWXUGO;
 106
 107         case 0xfe6:     /* UnixExec */
 108                 rmask = S_IRUGO | S_IXUGO;
 109                 break;
 110
 111         default:
 112                 rmask = S_IRUGO;
 113         }
 114
 115         mode = S_IFREG;
 116
 117         if (attr & ADFS_NDA_OWNER_READ)
 118                 mode |= rmask & asb->s_owner_mask;
 119
 120         if (attr & ADFS_NDA_OWNER_WRITE)
 121                 mode |= S_IWUGO & asb->s_owner_mask;
 122
 123         if (attr & ADFS_NDA_PUBLIC_READ)
 124                 mode |= rmask & asb->s_other_mask;
 125
 126         if (attr & ADFS_NDA_PUBLIC_WRITE)
 127                 mode |= S_IWUGO & asb->s_other_mask;
 128         return mode;
 129 }
 130
 131 /*
 132  * Convert Linux permission to ADFS attribute.  We try to do the reverse
 133  * of atts2mode, but there is not a 1:1 translation.
 134  */
 135 static int
 136 adfs_mode2atts(struct super_block *sb, struct inode *inode)
 137 {
 138         umode_t mode;
 139         int attr;
 140         struct adfs_sb_info *asb = ADFS_SB(sb);
 141
 142         /* FIXME: should we be able to alter a link? */
 143         if (S_ISLNK(inode->i_mode))
 144                 return ADFS_I(inode)->attr;
 145
 146         if (S_ISDIR(inode->i_mode))
 147                 attr = ADFS_NDA_DIRECTORY;
 148         else
 149                 attr = 0;
 150
 151         mode = inode->i_mode & asb->s_owner_mask;
 152         if (mode & S_IRUGO)
 153                 attr |= ADFS_NDA_OWNER_READ;
 154         if (mode & S_IWUGO)
 155                 attr |= ADFS_NDA_OWNER_WRITE;
 156
 157         mode = inode->i_mode & asb->s_other_mask;
 158         mode &= ~asb->s_owner_mask;
 159         if (mode & S_IRUGO)
 160                 attr |= ADFS_NDA_PUBLIC_READ;
 161         if (mode & S_IWUGO)
 162                 attr |= ADFS_NDA_PUBLIC_WRITE;
 163
 164         return attr;
 165 }
 166
 167 /*
 168  * Convert an ADFS time to Unix time.  ADFS has a 40-bit centi-second time
 169  * referenced to 1 Jan 1900 (til 2248)
 170  */
 171 static void
 172 adfs_adfs2unix_time(struct timespec *tv, struct inode *inode)
 173 {
 174         unsigned int high, low;
 175
 176         if (ADFS_I(inode)->stamped == 0)
 177                 goto cur_time;
 178
 179         high = ADFS_I(inode)->loadaddr << 24;
 180         low  = ADFS_I(inode)->execaddr;
 181
 182         high |= low >> 8;
 183         low  &= 255;
 184
 185         /* Files dated pre  01 Jan 1970 00:00:00. */
 186         if (high < 0x336e996a)
 187                 goto too_early;
 188
 189         /* Files dated post 18 Jan 2038 03:14:05. */
 190         if (high >= 0x656e9969)
 191                 goto too_late;
 192
 193         /* discard 2208988800 (0x336e996a00) seconds of time */
 194         high -= 0x336e996a;
 195
 196         /* convert 40-bit centi-seconds to 32-bit seconds */
 197         tv->tv_sec = (((high % 100) << 8) + low) / 100 + (high / 100 << 8);
 198         tv->tv_nsec = 0;
 199         return;
 200
 201  cur_time:
 202         *tv = CURRENT_TIME_SEC;
 203         return;
 204
 205  too_early:
 206         tv->tv_sec = tv->tv_nsec = 0;
 207         return;
 208
 209  too_late:
 210         tv->tv_sec = 0x7ffffffd;
 211         tv->tv_nsec = 0;
 212         return;
 213 }
 214
 215 /*
 216  * Convert an Unix time to ADFS time.  We only do this if the entry has a
 217  * time/date stamp already.
 218  */
 219 static void
 220 adfs_unix2adfs_time(struct inode *inode, unsigned int secs)
 221 {
 222         unsigned int high, low;
 223
 224         if (ADFS_I(inode)->stamped) {
 225                 /* convert 32-bit seconds to 40-bit centi-seconds */
 226                 low  = (secs & 255) * 100;
 227                 high = (secs / 256) * 100 + (low >> 8) + 0x336e996a;
 228
 229                 ADFS_I(inode)->loadaddr = (high >> 24) |
 230                                 (ADFS_I(inode)->loadaddr & ~0xff);
 231                 ADFS_I(inode)->execaddr = (low & 255) | (high << 8);
 232         }
 233 }
 234
 235 /*
 236  * Fill in the inode information from the object information.
 237  *
 238  * Note that this is an inode-less filesystem, so we can't use the inode
 239  * number to reference the metadata on the media.  Instead, we use the
 240  * inode number to hold the object ID, which in turn will tell us where
 241  * the data is held.  We also save the parent object ID, and with these
 242  * two, we can locate the metadata.
 243  *
 244  * This does mean that we rely on an objects parent remaining the same at
 245  * all times - we cannot cope with a cross-directory rename (yet).
 246  */
 247 struct inode *
 248 adfs_iget(struct super_block *sb, struct object_info *obj)
 249 {
 250         struct inode *inode;
 251
 252         inode = new_inode(sb);
 253         if (!inode)
 254                 goto out;
 255
 256         inode->i_uid     = ADFS_SB(sb)->s_uid;
 257         inode->i_gid     = ADFS_SB(sb)->s_gid;
 258         inode->i_ino     = obj->file_id;
 259         inode->i_size    = obj->size;
 260         inode->i_nlink   = 2;
 261         inode->i_blocks  = (inode->i_size + sb->s_blocksize - 1) >>
 262                             sb->s_blocksize_bits;
 263
 264         /*
 265          * we need to save the parent directory ID so that
 266          * write_inode can update the directory information
 267          * for this file.  This will need special handling
 268          * for cross-directory renames.
 269          */
 270         ADFS_I(inode)->parent_id = obj->parent_id;
 271         ADFS_I(inode)->loadaddr  = obj->loadaddr;
 272         ADFS_I(inode)->execaddr  = obj->execaddr;
 273         ADFS_I(inode)->attr      = obj->attr;
 274         ADFS_I(inode)->stamped    = ((obj->loadaddr & 0xfff00000) == 0xfff00000);
 275
 276         inode->i_mode    = adfs_atts2mode(sb, inode);
 277         adfs_adfs2unix_time(&inode->i_mtime, inode);
 278         inode->i_atime = inode->i_mtime;
 279         inode->i_ctime = inode->i_mtime;
 280
 281         if (S_ISDIR(inode->i_mode)) {
 282                 inode->i_op     = &adfs_dir_inode_operations;
 283                 inode->i_fop    = &adfs_dir_operations;
 284         } else if (S_ISREG(inode->i_mode)) {
 285                 inode->i_op     = &adfs_file_inode_operations;
 286                 inode->i_fop    = &adfs_file_operations;
 287                 inode->i_mapping->a_ops = &adfs_aops;
 288                 ADFS_I(inode)->mmu_private = inode->i_size;
 289         }
 290
 291         insert_inode_hash(inode);
 292
 293 out:
 294         return inode;
 295 }
 296
 297 /*
 298  * Validate and convert a changed access mode/time to their ADFS equivalents.
 299  * adfs_write_inode will actually write the information back to the directory
 300  * later.
 301  */
 302 int
 303 adfs_notify_change(struct dentry *dentry, struct iattr *attr)
 304 {
 305         struct inode *inode = dentry->d_inode;
 306         struct super_block *sb = inode->i_sb;
 307         unsigned int ia_valid = attr->ia_valid;
 308         int error;
 309
 310         lock_kernel();
 311
 312         error = inode_change_ok(inode, attr);
 313
 314         /*
 315          * we can't change the UID or GID of any file -
 316          * we have a global UID/GID in the superblock
 317          */
 318         if ((ia_valid & ATTR_UID && attr->ia_uid != ADFS_SB(sb)->s_uid) ||
 319             (ia_valid & ATTR_GID && attr->ia_gid != ADFS_SB(sb)->s_gid))
 320                 error = -EPERM;
 321
 322         if (error)
 323                 goto out;
 324
 325         if (ia_valid & ATTR_SIZE)
 326                 error = vmtruncate(inode, attr->ia_size);
 327
 328         if (error)
 329                 goto out;
 330
 331         if (ia_valid & ATTR_MTIME) {
 332                 inode->i_mtime = attr->ia_mtime;
 333                 adfs_unix2adfs_time(inode, attr->ia_mtime.tv_sec);
 334         }
 335         /*
 336          * FIXME: should we make these == to i_mtime since we don't
 337          * have the ability to represent them in our filesystem?
 338          */
 339         if (ia_valid & ATTR_ATIME)
 340                 inode->i_atime = attr->ia_atime;
 341         if (ia_valid & ATTR_CTIME)
 342                 inode->i_ctime = attr->ia_ctime;
 343         if (ia_valid & ATTR_MODE) {
 344                 ADFS_I(inode)->attr = adfs_mode2atts(sb, inode);
 345                 inode->i_mode = adfs_atts2mode(sb, inode);
 346         }
 347
 348         /*
 349          * FIXME: should we be marking this inode dirty even if
 350          * we don't have any metadata to write back?
 351          */
 352         if (ia_valid & (ATTR_SIZE | ATTR_MTIME | ATTR_MODE))
 353                 mark_inode_dirty(inode);
 354 out:
 355         unlock_kernel();
 356         return error;
 357 }
 358
 359 /*
 360  * write an existing inode back to the directory, and therefore the disk.
 361  * The adfs-specific inode data has already been updated by
 362  * adfs_notify_change()
 363  */
 364 int adfs_write_inode(struct inode *inode, struct writeback_control *wbc)
 365 {
 366         struct super_block *sb = inode->i_sb;
 367         struct object_info obj;
 368         int ret;
 369
 370         lock_kernel();
 371         obj.file_id     = inode->i_ino;
 372         obj.name_len    = 0;
 373         obj.parent_id   = ADFS_I(inode)->parent_id;
 374         obj.loadaddr    = ADFS_I(inode)->loadaddr;
 375         obj.execaddr    = ADFS_I(inode)->execaddr;
 376         obj.attr        = ADFS_I(inode)->attr;
 377         obj.size        = inode->i_size;
 378
 379         ret = adfs_dir_update(sb, &obj, wbc->sync_mode == WB_SYNC_ALL);
 380         unlock_kernel();
 381         return ret;
 382 }