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         int ret;
  54
  55         *pagep = NULL;
  56         ret = cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
  57                                 adfs_get_block,
  58                                 &ADFS_I(mapping->host)->mmu_private);
  59         if (unlikely(ret)) {
  60                 loff_t isize = mapping->host->i_size;
  61                 if (pos + len > isize)
  62                         vmtruncate(mapping->host, isize);
  63         }
  64
  65         return ret;
  66 }
  67
  68 static sector_t _adfs_bmap(struct address_space *mapping, sector_t block)
  69 {
  70         return generic_block_bmap(mapping, block, adfs_get_block);
  71 }
  72
  73 static const struct address_space_operations adfs_aops = {
  74         .readpage       = adfs_readpage,
  75         .writepage      = adfs_writepage,
  76         .sync_page      = block_sync_page,
  77         .write_begin    = adfs_write_begin,
  78         .write_end      = generic_write_end,
  79         .bmap           = _adfs_bmap
  80 };
  81
  82 static inline unsigned int
  83 adfs_filetype(struct inode *inode)
  84 {
  85         unsigned int type;
  86
  87         if (ADFS_I(inode)->stamped)
  88                 type = (ADFS_I(inode)->loadaddr >> 8) & 0xfff;
  89         else
  90                 type = (unsigned int) -1;
  91
  92         return type;
  93 }
  94
  95 /*
  96  * Convert ADFS attributes and filetype to Linux permission.
  97  */
  98 static umode_t
  99 adfs_atts2mode(struct super_block *sb, struct inode *inode)
 100 {
 101         unsigned int filetype, attr = ADFS_I(inode)->attr;
 102         umode_t mode, rmask;
 103         struct adfs_sb_info *asb = ADFS_SB(sb);
 104
 105         if (attr & ADFS_NDA_DIRECTORY) {
 106                 mode = S_IRUGO & asb->s_owner_mask;
 107                 return S_IFDIR | S_IXUGO | mode;
 108         }
 109
 110         filetype = adfs_filetype(inode);
 111
 112         switch (filetype) {
 113         case 0xfc0:     /* LinkFS */
 114                 return S_IFLNK|S_IRWXUGO;
 115
 116         case 0xfe6:     /* UnixExec */
 117                 rmask = S_IRUGO | S_IXUGO;
 118                 break;
 119
 120         default:
 121                 rmask = S_IRUGO;
 122         }
 123
 124         mode = S_IFREG;
 125
 126         if (attr & ADFS_NDA_OWNER_READ)
 127                 mode |= rmask & asb->s_owner_mask;
 128
 129         if (attr & ADFS_NDA_OWNER_WRITE)
 130                 mode |= S_IWUGO & asb->s_owner_mask;
 131
 132         if (attr & ADFS_NDA_PUBLIC_READ)
 133                 mode |= rmask & asb->s_other_mask;
 134
 135         if (attr & ADFS_NDA_PUBLIC_WRITE)
 136                 mode |= S_IWUGO & asb->s_other_mask;
 137         return mode;
 138 }
 139
 140 /*
 141  * Convert Linux permission to ADFS attribute.  We try to do the reverse
 142  * of atts2mode, but there is not a 1:1 translation.
 143  */
 144 static int
 145 adfs_mode2atts(struct super_block *sb, struct inode *inode)
 146 {
 147         umode_t mode;
 148         int attr;
 149         struct adfs_sb_info *asb = ADFS_SB(sb);
 150
 151         /* FIXME: should we be able to alter a link? */
 152         if (S_ISLNK(inode->i_mode))
 153                 return ADFS_I(inode)->attr;
 154
 155         if (S_ISDIR(inode->i_mode))
 156                 attr = ADFS_NDA_DIRECTORY;
 157         else
 158                 attr = 0;
 159
 160         mode = inode->i_mode & asb->s_owner_mask;
 161         if (mode & S_IRUGO)
 162                 attr |= ADFS_NDA_OWNER_READ;
 163         if (mode & S_IWUGO)
 164                 attr |= ADFS_NDA_OWNER_WRITE;
 165
 166         mode = inode->i_mode & asb->s_other_mask;
 167         mode &= ~asb->s_owner_mask;
 168         if (mode & S_IRUGO)
 169                 attr |= ADFS_NDA_PUBLIC_READ;
 170         if (mode & S_IWUGO)
 171                 attr |= ADFS_NDA_PUBLIC_WRITE;
 172
 173         return attr;
 174 }
 175
 176 /*
 177  * Convert an ADFS time to Unix time.  ADFS has a 40-bit centi-second time
 178  * referenced to 1 Jan 1900 (til 2248)
 179  */
 180 static void
 181 adfs_adfs2unix_time(struct timespec *tv, struct inode *inode)
 182 {
 183         unsigned int high, low;
 184
 185         if (ADFS_I(inode)->stamped == 0)
 186                 goto cur_time;
 187
 188         high = ADFS_I(inode)->loadaddr << 24;
 189         low  = ADFS_I(inode)->execaddr;
 190
 191         high |= low >> 8;
 192         low  &= 255;
 193
 194         /* Files dated pre  01 Jan 1970 00:00:00. */
 195         if (high < 0x336e996a)
 196                 goto too_early;
 197
 198         /* Files dated post 18 Jan 2038 03:14:05. */
 199         if (high >= 0x656e9969)
 200                 goto too_late;
 201
 202         /* discard 2208988800 (0x336e996a00) seconds of time */
 203         high -= 0x336e996a;
 204
 205         /* convert 40-bit centi-seconds to 32-bit seconds */
 206         tv->tv_sec = (((high % 100) << 8) + low) / 100 + (high / 100 << 8);
 207         tv->tv_nsec = 0;
 208         return;
 209
 210  cur_time:
 211         *tv = CURRENT_TIME_SEC;
 212         return;
 213
 214  too_early:
 215         tv->tv_sec = tv->tv_nsec = 0;
 216         return;
 217
 218  too_late:
 219         tv->tv_sec = 0x7ffffffd;
 220         tv->tv_nsec = 0;
 221         return;
 222 }
 223
 224 /*
 225  * Convert an Unix time to ADFS time.  We only do this if the entry has a
 226  * time/date stamp already.
 227  */
 228 static void
 229 adfs_unix2adfs_time(struct inode *inode, unsigned int secs)
 230 {
 231         unsigned int high, low;
 232
 233         if (ADFS_I(inode)->stamped) {
 234                 /* convert 32-bit seconds to 40-bit centi-seconds */
 235                 low  = (secs & 255) * 100;
 236                 high = (secs / 256) * 100 + (low >> 8) + 0x336e996a;
 237
 238                 ADFS_I(inode)->loadaddr = (high >> 24) |
 239                                 (ADFS_I(inode)->loadaddr & ~0xff);
 240                 ADFS_I(inode)->execaddr = (low & 255) | (high << 8);
 241         }
 242 }
 243
 244 /*
 245  * Fill in the inode information from the object information.
 246  *
 247  * Note that this is an inode-less filesystem, so we can't use the inode
 248  * number to reference the metadata on the media.  Instead, we use the
 249  * inode number to hold the object ID, which in turn will tell us where
 250  * the data is held.  We also save the parent object ID, and with these
 251  * two, we can locate the metadata.
 252  *
 253  * This does mean that we rely on an objects parent remaining the same at
 254  * all times - we cannot cope with a cross-directory rename (yet).
 255  */
 256 struct inode *
 257 adfs_iget(struct super_block *sb, struct object_info *obj)
 258 {
 259         struct inode *inode;
 260
 261         inode = new_inode(sb);
 262         if (!inode)
 263                 goto out;
 264
 265         inode->i_uid     = ADFS_SB(sb)->s_uid;
 266         inode->i_gid     = ADFS_SB(sb)->s_gid;
 267         inode->i_ino     = obj->file_id;
 268         inode->i_size    = obj->size;
 269         inode->i_nlink   = 2;
 270         inode->i_blocks  = (inode->i_size + sb->s_blocksize - 1) >>
 271                             sb->s_blocksize_bits;
 272
 273         /*
 274          * we need to save the parent directory ID so that
 275          * write_inode can update the directory information
 276          * for this file.  This will need special handling
 277          * for cross-directory renames.
 278          */
 279         ADFS_I(inode)->parent_id = obj->parent_id;
 280         ADFS_I(inode)->loadaddr  = obj->loadaddr;
 281         ADFS_I(inode)->execaddr  = obj->execaddr;
 282         ADFS_I(inode)->attr      = obj->attr;
 283         ADFS_I(inode)->stamped    = ((obj->loadaddr & 0xfff00000) == 0xfff00000);
 284
 285         inode->i_mode    = adfs_atts2mode(sb, inode);
 286         adfs_adfs2unix_time(&inode->i_mtime, inode);
 287         inode->i_atime = inode->i_mtime;
 288         inode->i_ctime = inode->i_mtime;
 289
 290         if (S_ISDIR(inode->i_mode)) {
 291                 inode->i_op     = &adfs_dir_inode_operations;
 292                 inode->i_fop    = &adfs_dir_operations;
 293         } else if (S_ISREG(inode->i_mode)) {
 294                 inode->i_op     = &adfs_file_inode_operations;
 295                 inode->i_fop    = &adfs_file_operations;
 296                 inode->i_mapping->a_ops = &adfs_aops;
 297                 ADFS_I(inode)->mmu_private = inode->i_size;
 298         }
 299
 300         insert_inode_hash(inode);
 301
 302 out:
 303         return inode;
 304 }
 305
 306 /*
 307  * Validate and convert a changed access mode/time to their ADFS equivalents.
 308  * adfs_write_inode will actually write the information back to the directory
 309  * later.
 310  */
 311 int
 312 adfs_notify_change(struct dentry *dentry, struct iattr *attr)
 313 {
 314         struct inode *inode = dentry->d_inode;
 315         struct super_block *sb = inode->i_sb;
 316         unsigned int ia_valid = attr->ia_valid;
 317         int error;
 318
 319         lock_kernel();
 320
 321         error = inode_change_ok(inode, attr);
 322
 323         /*
 324          * we can't change the UID or GID of any file -
 325          * we have a global UID/GID in the superblock
 326          */
 327         if ((ia_valid & ATTR_UID && attr->ia_uid != ADFS_SB(sb)->s_uid) ||
 328             (ia_valid & ATTR_GID && attr->ia_gid != ADFS_SB(sb)->s_gid))
 329                 error = -EPERM;
 330
 331         if (error)
 332                 goto out;
 333
 334         /* XXX: this is missing some actual on-disk truncation.. */
 335         if (ia_valid & ATTR_SIZE)
 336                 truncate_setsize(inode, attr->ia_size);
 337
 338         if (ia_valid & ATTR_MTIME) {
 339                 inode->i_mtime = attr->ia_mtime;
 340                 adfs_unix2adfs_time(inode, attr->ia_mtime.tv_sec);
 341         }
 342         /*
 343          * FIXME: should we make these == to i_mtime since we don't
 344          * have the ability to represent them in our filesystem?
 345          */
 346         if (ia_valid & ATTR_ATIME)
 347                 inode->i_atime = attr->ia_atime;
 348         if (ia_valid & ATTR_CTIME)
 349                 inode->i_ctime = attr->ia_ctime;
 350         if (ia_valid & ATTR_MODE) {
 351                 ADFS_I(inode)->attr = adfs_mode2atts(sb, inode);
 352                 inode->i_mode = adfs_atts2mode(sb, inode);
 353         }
 354
 355         /*
 356          * FIXME: should we be marking this inode dirty even if
 357          * we don't have any metadata to write back?
 358          */
 359         if (ia_valid & (ATTR_SIZE | ATTR_MTIME | ATTR_MODE))
 360                 mark_inode_dirty(inode);
 361 out:
 362         unlock_kernel();
 363         return error;
 364 }
 365
 366 /*
 367  * write an existing inode back to the directory, and therefore the disk.
 368  * The adfs-specific inode data has already been updated by
 369  * adfs_notify_change()
 370  */
 371 int adfs_write_inode(struct inode *inode, struct writeback_control *wbc)
 372 {
 373         struct super_block *sb = inode->i_sb;
 374         struct object_info obj;
 375         int ret;
 376
 377         lock_kernel();
 378         obj.file_id     = inode->i_ino;
 379         obj.name_len    = 0;
 380         obj.parent_id   = ADFS_I(inode)->parent_id;
 381         obj.loadaddr    = ADFS_I(inode)->loadaddr;
 382         obj.execaddr    = ADFS_I(inode)->execaddr;
 383         obj.attr        = ADFS_I(inode)->attr;
 384         obj.size        = inode->i_size;
 385
 386         ret = adfs_dir_update(sb, &obj, wbc->sync_mode == WB_SYNC_ALL);
 387         unlock_kernel();
 388         return ret;
 389 }