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/buffer_head.h>
  11 #include <linux/writeback.h>
  12 #include "adfs.h"
  13
  14 /*
  15  * Lookup/Create a block at offset 'block' into 'inode'.  We currently do
  16  * not support creation of new blocks, so we return -EIO for this case.
  17  */
  18 static int
  19 adfs_get_block(struct inode *inode, sector_t block, struct buffer_head *bh,
  20                int create)
  21 {
  22         if (!create) {
  23                 if (block >= inode->i_blocks)
  24                         goto abort_toobig;
  25
  26                 block = __adfs_block_map(inode->i_sb, inode->i_ino, block);
  27                 if (block)
  28                         map_bh(bh, inode->i_sb, block);
  29                 return 0;
  30         }
  31         /* don't support allocation of blocks yet */
  32         return -EIO;
  33
  34 abort_toobig:
  35         return 0;
  36 }
  37
  38 static int adfs_writepage(struct page *page, struct writeback_control *wbc)
  39 {
  40         return block_write_full_page(page, adfs_get_block, wbc);
  41 }
  42
  43 static int adfs_readpage(struct file *file, struct page *page)
  44 {
  45         return block_read_full_page(page, adfs_get_block);
  46 }
  47
  48 static int adfs_write_begin(struct file *file, struct address_space *mapping,
  49                         loff_t pos, unsigned len, unsigned flags,
  50                         struct page **pagep, void **fsdata)
  51 {
  52         int ret;
  53
  54         *pagep = NULL;
  55         ret = cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
  56                                 adfs_get_block,
  57                                 &ADFS_I(mapping->host)->mmu_private);
  58         if (unlikely(ret)) {
  59                 loff_t isize = mapping->host->i_size;
  60                 if (pos + len > isize)
  61                         vmtruncate(mapping->host, isize);
  62         }
  63
  64         return ret;
  65 }
  66
  67 static sector_t _adfs_bmap(struct address_space *mapping, sector_t block)
  68 {
  69         return generic_block_bmap(mapping, block, adfs_get_block);
  70 }
  71
  72 static const struct address_space_operations adfs_aops = {
  73         .readpage       = adfs_readpage,
  74         .writepage      = adfs_writepage,
  75         .sync_page      = block_sync_page,
  76         .write_begin    = adfs_write_begin,
  77         .write_end      = generic_write_end,
  78         .bmap           = _adfs_bmap
  79 };
  80
  81 static inline unsigned int
  82 adfs_filetype(struct inode *inode)
  83 {
  84         unsigned int type;
  85
  86         if (ADFS_I(inode)->stamped)
  87                 type = (ADFS_I(inode)->loadaddr >> 8) & 0xfff;
  88         else
  89                 type = (unsigned int) -1;
  90
  91         return type;
  92 }
  93
  94 /*
  95  * Convert ADFS attributes and filetype to Linux permission.
  96  */
  97 static umode_t
  98 adfs_atts2mode(struct super_block *sb, struct inode *inode)
  99 {
 100         unsigned int filetype, attr = ADFS_I(inode)->attr;
 101         umode_t mode, rmask;
 102         struct adfs_sb_info *asb = ADFS_SB(sb);
 103
 104         if (attr & ADFS_NDA_DIRECTORY) {
 105                 mode = S_IRUGO & asb->s_owner_mask;
 106                 return S_IFDIR | S_IXUGO | mode;
 107         }
 108
 109         filetype = adfs_filetype(inode);
 110
 111         switch (filetype) {
 112         case 0xfc0:     /* LinkFS */
 113                 return S_IFLNK|S_IRWXUGO;
 114
 115         case 0xfe6:     /* UnixExec */
 116                 rmask = S_IRUGO | S_IXUGO;
 117                 break;
 118
 119         default:
 120                 rmask = S_IRUGO;
 121         }
 122
 123         mode = S_IFREG;
 124
 125         if (attr & ADFS_NDA_OWNER_READ)
 126                 mode |= rmask & asb->s_owner_mask;
 127
 128         if (attr & ADFS_NDA_OWNER_WRITE)
 129                 mode |= S_IWUGO & asb->s_owner_mask;
 130
 131         if (attr & ADFS_NDA_PUBLIC_READ)
 132                 mode |= rmask & asb->s_other_mask;
 133
 134         if (attr & ADFS_NDA_PUBLIC_WRITE)
 135                 mode |= S_IWUGO & asb->s_other_mask;
 136         return mode;
 137 }
 138
 139 /*
 140  * Convert Linux permission to ADFS attribute.  We try to do the reverse
 141  * of atts2mode, but there is not a 1:1 translation.
 142  */
 143 static int
 144 adfs_mode2atts(struct super_block *sb, struct inode *inode)
 145 {
 146         umode_t mode;
 147         int attr;
 148         struct adfs_sb_info *asb = ADFS_SB(sb);
 149
 150         /* FIXME: should we be able to alter a link? */
 151         if (S_ISLNK(inode->i_mode))
 152                 return ADFS_I(inode)->attr;
 153
 154         if (S_ISDIR(inode->i_mode))
 155                 attr = ADFS_NDA_DIRECTORY;
 156         else
 157                 attr = 0;
 158
 159         mode = inode->i_mode & asb->s_owner_mask;
 160         if (mode & S_IRUGO)
 161                 attr |= ADFS_NDA_OWNER_READ;
 162         if (mode & S_IWUGO)
 163                 attr |= ADFS_NDA_OWNER_WRITE;
 164
 165         mode = inode->i_mode & asb->s_other_mask;
 166         mode &= ~asb->s_owner_mask;
 167         if (mode & S_IRUGO)
 168                 attr |= ADFS_NDA_PUBLIC_READ;
 169         if (mode & S_IWUGO)
 170                 attr |= ADFS_NDA_PUBLIC_WRITE;
 171
 172         return attr;
 173 }
 174
 175 /*
 176  * Convert an ADFS time to Unix time.  ADFS has a 40-bit centi-second time
 177  * referenced to 1 Jan 1900 (til 2248)
 178  */
 179 static void
 180 adfs_adfs2unix_time(struct timespec *tv, struct inode *inode)
 181 {
 182         unsigned int high, low;
 183
 184         if (ADFS_I(inode)->stamped == 0)
 185                 goto cur_time;
 186
 187         high = ADFS_I(inode)->loadaddr << 24;
 188         low  = ADFS_I(inode)->execaddr;
 189
 190         high |= low >> 8;
 191         low  &= 255;
 192
 193         /* Files dated pre  01 Jan 1970 00:00:00. */
 194         if (high < 0x336e996a)
 195                 goto too_early;
 196
 197         /* Files dated post 18 Jan 2038 03:14:05. */
 198         if (high >= 0x656e9969)
 199                 goto too_late;
 200
 201         /* discard 2208988800 (0x336e996a00) seconds of time */
 202         high -= 0x336e996a;
 203
 204         /* convert 40-bit centi-seconds to 32-bit seconds */
 205         tv->tv_sec = (((high % 100) << 8) + low) / 100 + (high / 100 << 8);
 206         tv->tv_nsec = 0;
 207         return;
 208
 209  cur_time:
 210         *tv = CURRENT_TIME_SEC;
 211         return;
 212
 213  too_early:
 214         tv->tv_sec = tv->tv_nsec = 0;
 215         return;
 216
 217  too_late:
 218         tv->tv_sec = 0x7ffffffd;
 219         tv->tv_nsec = 0;
 220         return;
 221 }
 222
 223 /*
 224  * Convert an Unix time to ADFS time.  We only do this if the entry has a
 225  * time/date stamp already.
 226  */
 227 static void
 228 adfs_unix2adfs_time(struct inode *inode, unsigned int secs)
 229 {
 230         unsigned int high, low;
 231
 232         if (ADFS_I(inode)->stamped) {
 233                 /* convert 32-bit seconds to 40-bit centi-seconds */
 234                 low  = (secs & 255) * 100;
 235                 high = (secs / 256) * 100 + (low >> 8) + 0x336e996a;
 236
 237                 ADFS_I(inode)->loadaddr = (high >> 24) |
 238                                 (ADFS_I(inode)->loadaddr & ~0xff);
 239                 ADFS_I(inode)->execaddr = (low & 255) | (high << 8);
 240         }
 241 }
 242
 243 /*
 244  * Fill in the inode information from the object information.
 245  *
 246  * Note that this is an inode-less filesystem, so we can't use the inode
 247  * number to reference the metadata on the media.  Instead, we use the
 248  * inode number to hold the object ID, which in turn will tell us where
 249  * the data is held.  We also save the parent object ID, and with these
 250  * two, we can locate the metadata.
 251  *
 252  * This does mean that we rely on an objects parent remaining the same at
 253  * all times - we cannot cope with a cross-directory rename (yet).
 254  */
 255 struct inode *
 256 adfs_iget(struct super_block *sb, struct object_info *obj)
 257 {
 258         struct inode *inode;
 259
 260         inode = new_inode(sb);
 261         if (!inode)
 262                 goto out;
 263
 264         inode->i_uid     = ADFS_SB(sb)->s_uid;
 265         inode->i_gid     = ADFS_SB(sb)->s_gid;
 266         inode->i_ino     = obj->file_id;
 267         inode->i_size    = obj->size;
 268         inode->i_nlink   = 2;
 269         inode->i_blocks  = (inode->i_size + sb->s_blocksize - 1) >>
 270                             sb->s_blocksize_bits;
 271
 272         /*
 273          * we need to save the parent directory ID so that
 274          * write_inode can update the directory information
 275          * for this file.  This will need special handling
 276          * for cross-directory renames.
 277          */
 278         ADFS_I(inode)->parent_id = obj->parent_id;
 279         ADFS_I(inode)->loadaddr  = obj->loadaddr;
 280         ADFS_I(inode)->execaddr  = obj->execaddr;
 281         ADFS_I(inode)->attr      = obj->attr;
 282         ADFS_I(inode)->stamped    = ((obj->loadaddr & 0xfff00000) == 0xfff00000);
 283
 284         inode->i_mode    = adfs_atts2mode(sb, inode);
 285         adfs_adfs2unix_time(&inode->i_mtime, inode);
 286         inode->i_atime = inode->i_mtime;
 287         inode->i_ctime = inode->i_mtime;
 288
 289         if (S_ISDIR(inode->i_mode)) {
 290                 inode->i_op     = &adfs_dir_inode_operations;
 291                 inode->i_fop    = &adfs_dir_operations;
 292         } else if (S_ISREG(inode->i_mode)) {
 293                 inode->i_op     = &adfs_file_inode_operations;
 294                 inode->i_fop    = &adfs_file_operations;
 295                 inode->i_mapping->a_ops = &adfs_aops;
 296                 ADFS_I(inode)->mmu_private = inode->i_size;
 297         }
 298
 299         insert_inode_hash(inode);
 300
 301 out:
 302         return inode;
 303 }
 304
 305 /*
 306  * Validate and convert a changed access mode/time to their ADFS equivalents.
 307  * adfs_write_inode will actually write the information back to the directory
 308  * later.
 309  */
 310 int
 311 adfs_notify_change(struct dentry *dentry, struct iattr *attr)
 312 {
 313         struct inode *inode = dentry->d_inode;
 314         struct super_block *sb = inode->i_sb;
 315         unsigned int ia_valid = attr->ia_valid;
 316         int error;
 317
 318         error = inode_change_ok(inode, attr);
 319
 320         /*
 321          * we can't change the UID or GID of any file -
 322          * we have a global UID/GID in the superblock
 323          */
 324         if ((ia_valid & ATTR_UID && attr->ia_uid != ADFS_SB(sb)->s_uid) ||
 325             (ia_valid & ATTR_GID && attr->ia_gid != ADFS_SB(sb)->s_gid))
 326                 error = -EPERM;
 327
 328         if (error)
 329                 goto out;
 330
 331         /* XXX: this is missing some actual on-disk truncation.. */
 332         if (ia_valid & ATTR_SIZE)
 333                 truncate_setsize(inode, attr->ia_size);
 334
 335         if (ia_valid & ATTR_MTIME) {
 336                 inode->i_mtime = attr->ia_mtime;
 337                 adfs_unix2adfs_time(inode, attr->ia_mtime.tv_sec);
 338         }
 339         /*
 340          * FIXME: should we make these == to i_mtime since we don't
 341          * have the ability to represent them in our filesystem?
 342          */
 343         if (ia_valid & ATTR_ATIME)
 344                 inode->i_atime = attr->ia_atime;
 345         if (ia_valid & ATTR_CTIME)
 346                 inode->i_ctime = attr->ia_ctime;
 347         if (ia_valid & ATTR_MODE) {
 348                 ADFS_I(inode)->attr = adfs_mode2atts(sb, inode);
 349                 inode->i_mode = adfs_atts2mode(sb, inode);
 350         }
 351
 352         /*
 353          * FIXME: should we be marking this inode dirty even if
 354          * we don't have any metadata to write back?
 355          */
 356         if (ia_valid & (ATTR_SIZE | ATTR_MTIME | ATTR_MODE))
 357                 mark_inode_dirty(inode);
 358 out:
 359         return error;
 360 }
 361
 362 /*
 363  * write an existing inode back to the directory, and therefore the disk.
 364  * The adfs-specific inode data has already been updated by
 365  * adfs_notify_change()
 366  */
 367 int adfs_write_inode(struct inode *inode, struct writeback_control *wbc)
 368 {
 369         struct super_block *sb = inode->i_sb;
 370         struct object_info obj;
 371         int ret;
 372
 373         obj.file_id     = inode->i_ino;
 374         obj.name_len    = 0;
 375         obj.parent_id   = ADFS_I(inode)->parent_id;
 376         obj.loadaddr    = ADFS_I(inode)->loadaddr;
 377         obj.execaddr    = ADFS_I(inode)->execaddr;
 378         obj.attr        = ADFS_I(inode)->attr;
 379         obj.size        = inode->i_size;
 380
 381         ret = adfs_dir_update(sb, &obj, wbc->sync_mode == WB_SYNC_ALL);
 382         return ret;
 383 }