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 void adfs_write_failed(struct address_space *mapping, loff_t to)
  49 {
  50         struct inode *inode = mapping->host;
  51
  52         if (to > inode->i_size)
  53                 truncate_pagecache(inode, inode->i_size);
  54 }
  55
  56 static int adfs_write_begin(struct file *file, struct address_space *mapping,
  57                         loff_t pos, unsigned len, unsigned flags,
  58                         struct page **pagep, void **fsdata)
  59 {
  60         int ret;
  61
  62         *pagep = NULL;
  63         ret = cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
  64                                 adfs_get_block,
  65                                 &ADFS_I(mapping->host)->mmu_private);
  66         if (unlikely(ret))
  67                 adfs_write_failed(mapping, pos + len);
  68
  69         return ret;
  70 }
  71
  72 static sector_t _adfs_bmap(struct address_space *mapping, sector_t block)
  73 {
  74         return generic_block_bmap(mapping, block, adfs_get_block);
  75 }
  76
  77 static const struct address_space_operations adfs_aops = {
  78         .readpage       = adfs_readpage,
  79         .writepage      = adfs_writepage,
  80         .write_begin    = adfs_write_begin,
  81         .write_end      = generic_write_end,
  82         .bmap           = _adfs_bmap
  83 };
  84
  85 /*
  86  * Convert ADFS attributes and filetype to Linux permission.
  87  */
  88 static umode_t
  89 adfs_atts2mode(struct super_block *sb, struct inode *inode)
  90 {
  91         unsigned int attr = ADFS_I(inode)->attr;
  92         umode_t mode, rmask;
  93         struct adfs_sb_info *asb = ADFS_SB(sb);
  94
  95         if (attr & ADFS_NDA_DIRECTORY) {
  96                 mode = S_IRUGO & asb->s_owner_mask;
  97                 return S_IFDIR | S_IXUGO | mode;
  98         }
  99
 100         switch (ADFS_I(inode)->filetype) {
 101         case 0xfc0:     /* LinkFS */
 102                 return S_IFLNK|S_IRWXUGO;
 103
 104         case 0xfe6:     /* UnixExec */
 105                 rmask = S_IRUGO | S_IXUGO;
 106                 break;
 107
 108         default:
 109                 rmask = S_IRUGO;
 110         }
 111
 112         mode = S_IFREG;
 113
 114         if (attr & ADFS_NDA_OWNER_READ)
 115                 mode |= rmask & asb->s_owner_mask;
 116
 117         if (attr & ADFS_NDA_OWNER_WRITE)
 118                 mode |= S_IWUGO & asb->s_owner_mask;
 119
 120         if (attr & ADFS_NDA_PUBLIC_READ)
 121                 mode |= rmask & asb->s_other_mask;
 122
 123         if (attr & ADFS_NDA_PUBLIC_WRITE)
 124                 mode |= S_IWUGO & asb->s_other_mask;
 125         return mode;
 126 }
 127
 128 /*
 129  * Convert Linux permission to ADFS attribute.  We try to do the reverse
 130  * of atts2mode, but there is not a 1:1 translation.
 131  */
 132 static int
 133 adfs_mode2atts(struct super_block *sb, struct inode *inode)
 134 {
 135         umode_t mode;
 136         int attr;
 137         struct adfs_sb_info *asb = ADFS_SB(sb);
 138
 139         /* FIXME: should we be able to alter a link? */
 140         if (S_ISLNK(inode->i_mode))
 141                 return ADFS_I(inode)->attr;
 142
 143         if (S_ISDIR(inode->i_mode))
 144                 attr = ADFS_NDA_DIRECTORY;
 145         else
 146                 attr = 0;
 147
 148         mode = inode->i_mode & asb->s_owner_mask;
 149         if (mode & S_IRUGO)
 150                 attr |= ADFS_NDA_OWNER_READ;
 151         if (mode & S_IWUGO)
 152                 attr |= ADFS_NDA_OWNER_WRITE;
 153
 154         mode = inode->i_mode & asb->s_other_mask;
 155         mode &= ~asb->s_owner_mask;
 156         if (mode & S_IRUGO)
 157                 attr |= ADFS_NDA_PUBLIC_READ;
 158         if (mode & S_IWUGO)
 159                 attr |= ADFS_NDA_PUBLIC_WRITE;
 160
 161         return attr;
 162 }
 163
 164 /*
 165  * Convert an ADFS time to Unix time.  ADFS has a 40-bit centi-second time
 166  * referenced to 1 Jan 1900 (til 2248) so we need to discard 2208988800 seconds
 167  * of time to convert from RISC OS epoch to Unix epoch.
 168  */
 169 static void
 170 adfs_adfs2unix_time(struct timespec *tv, struct inode *inode)
 171 {
 172         unsigned int high, low;
 173         /* 01 Jan 1970 00:00:00 (Unix epoch) as nanoseconds since
 174          * 01 Jan 1900 00:00:00 (RISC OS epoch)
 175          */
 176         static const s64 nsec_unix_epoch_diff_risc_os_epoch =
 177                                                         2208988800000000000LL;
 178         s64 nsec;
 179
 180         if (ADFS_I(inode)->stamped == 0)
 181                 goto cur_time;
 182
 183         high = ADFS_I(inode)->loadaddr & 0xFF; /* top 8 bits of timestamp */
 184         low  = ADFS_I(inode)->execaddr;    /* bottom 32 bits of timestamp */
 185
 186         /* convert 40-bit centi-seconds to 32-bit seconds
 187          * going via nanoseconds to retain precision
 188          */
 189         nsec = (((s64) high << 32) | (s64) low) * 10000000; /* cs to ns */
 190
 191         /* Files dated pre  01 Jan 1970 00:00:00. */
 192         if (nsec < nsec_unix_epoch_diff_risc_os_epoch)
 193                 goto too_early;
 194
 195         /* convert from RISC OS to Unix epoch */
 196         nsec -= nsec_unix_epoch_diff_risc_os_epoch;
 197
 198         *tv = ns_to_timespec(nsec);
 199         return;
 200
 201  cur_time:
 202         *tv = CURRENT_TIME;
 203         return;
 204
 205  too_early:
 206         tv->tv_sec = tv->tv_nsec = 0;
 207         return;
 208 }
 209
 210 /*
 211  * Convert an Unix time to ADFS time.  We only do this if the entry has a
 212  * time/date stamp already.
 213  */
 214 static void
 215 adfs_unix2adfs_time(struct inode *inode, unsigned int secs)
 216 {
 217         unsigned int high, low;
 218
 219         if (ADFS_I(inode)->stamped) {
 220                 /* convert 32-bit seconds to 40-bit centi-seconds */
 221                 low  = (secs & 255) * 100;
 222                 high = (secs / 256) * 100 + (low >> 8) + 0x336e996a;
 223
 224                 ADFS_I(inode)->loadaddr = (high >> 24) |
 225                                 (ADFS_I(inode)->loadaddr & ~0xff);
 226                 ADFS_I(inode)->execaddr = (low & 255) | (high << 8);
 227         }
 228 }
 229
 230 /*
 231  * Fill in the inode information from the object information.
 232  *
 233  * Note that this is an inode-less filesystem, so we can't use the inode
 234  * number to reference the metadata on the media.  Instead, we use the
 235  * inode number to hold the object ID, which in turn will tell us where
 236  * the data is held.  We also save the parent object ID, and with these
 237  * two, we can locate the metadata.
 238  *
 239  * This does mean that we rely on an objects parent remaining the same at
 240  * all times - we cannot cope with a cross-directory rename (yet).
 241  */
 242 struct inode *
 243 adfs_iget(struct super_block *sb, struct object_info *obj)
 244 {
 245         struct inode *inode;
 246
 247         inode = new_inode(sb);
 248         if (!inode)
 249                 goto out;
 250
 251         inode->i_uid     = ADFS_SB(sb)->s_uid;
 252         inode->i_gid     = ADFS_SB(sb)->s_gid;
 253         inode->i_ino     = obj->file_id;
 254         inode->i_size    = obj->size;
 255         set_nlink(inode, 2);
 256         inode->i_blocks  = (inode->i_size + sb->s_blocksize - 1) >>
 257                             sb->s_blocksize_bits;
 258
 259         /*
 260          * we need to save the parent directory ID so that
 261          * write_inode can update the directory information
 262          * for this file.  This will need special handling
 263          * for cross-directory renames.
 264          */
 265         ADFS_I(inode)->parent_id = obj->parent_id;
 266         ADFS_I(inode)->loadaddr  = obj->loadaddr;
 267         ADFS_I(inode)->execaddr  = obj->execaddr;
 268         ADFS_I(inode)->attr      = obj->attr;
 269         ADFS_I(inode)->filetype  = obj->filetype;
 270         ADFS_I(inode)->stamped   = ((obj->loadaddr & 0xfff00000) == 0xfff00000);
 271
 272         inode->i_mode    = adfs_atts2mode(sb, inode);
 273         adfs_adfs2unix_time(&inode->i_mtime, inode);
 274         inode->i_atime = inode->i_mtime;
 275         inode->i_ctime = inode->i_mtime;
 276
 277         if (S_ISDIR(inode->i_mode)) {
 278                 inode->i_op     = &adfs_dir_inode_operations;
 279                 inode->i_fop    = &adfs_dir_operations;
 280         } else if (S_ISREG(inode->i_mode)) {
 281                 inode->i_op     = &adfs_file_inode_operations;
 282                 inode->i_fop    = &adfs_file_operations;
 283                 inode->i_mapping->a_ops = &adfs_aops;
 284                 ADFS_I(inode)->mmu_private = inode->i_size;
 285         }
 286
 287         insert_inode_hash(inode);
 288
 289 out:
 290         return inode;
 291 }
 292
 293 /*
 294  * Validate and convert a changed access mode/time to their ADFS equivalents.
 295  * adfs_write_inode will actually write the information back to the directory
 296  * later.
 297  */
 298 int
 299 adfs_notify_change(struct dentry *dentry, struct iattr *attr)
 300 {
 301         struct inode *inode = d_inode(dentry);
 302         struct super_block *sb = inode->i_sb;
 303         unsigned int ia_valid = attr->ia_valid;
 304         int error;
 305
 306         error = inode_change_ok(inode, attr);
 307
 308         /*
 309          * we can't change the UID or GID of any file -
 310          * we have a global UID/GID in the superblock
 311          */
 312         if ((ia_valid & ATTR_UID && !uid_eq(attr->ia_uid, ADFS_SB(sb)->s_uid)) ||
 313             (ia_valid & ATTR_GID && !gid_eq(attr->ia_gid, ADFS_SB(sb)->s_gid)))
 314                 error = -EPERM;
 315
 316         if (error)
 317                 goto out;
 318
 319         /* XXX: this is missing some actual on-disk truncation.. */
 320         if (ia_valid & ATTR_SIZE)
 321                 truncate_setsize(inode, attr->ia_size);
 322
 323         if (ia_valid & ATTR_MTIME) {
 324                 inode->i_mtime = attr->ia_mtime;
 325                 adfs_unix2adfs_time(inode, attr->ia_mtime.tv_sec);
 326         }
 327         /*
 328          * FIXME: should we make these == to i_mtime since we don't
 329          * have the ability to represent them in our filesystem?
 330          */
 331         if (ia_valid & ATTR_ATIME)
 332                 inode->i_atime = attr->ia_atime;
 333         if (ia_valid & ATTR_CTIME)
 334                 inode->i_ctime = attr->ia_ctime;
 335         if (ia_valid & ATTR_MODE) {
 336                 ADFS_I(inode)->attr = adfs_mode2atts(sb, inode);
 337                 inode->i_mode = adfs_atts2mode(sb, inode);
 338         }
 339
 340         /*
 341          * FIXME: should we be marking this inode dirty even if
 342          * we don't have any metadata to write back?
 343          */
 344         if (ia_valid & (ATTR_SIZE | ATTR_MTIME | ATTR_MODE))
 345                 mark_inode_dirty(inode);
 346 out:
 347         return error;
 348 }
 349
 350 /*
 351  * write an existing inode back to the directory, and therefore the disk.
 352  * The adfs-specific inode data has already been updated by
 353  * adfs_notify_change()
 354  */
 355 int adfs_write_inode(struct inode *inode, struct writeback_control *wbc)
 356 {
 357         struct super_block *sb = inode->i_sb;
 358         struct object_info obj;
 359         int ret;
 360
 361         obj.file_id     = inode->i_ino;
 362         obj.name_len    = 0;
 363         obj.parent_id   = ADFS_I(inode)->parent_id;
 364         obj.loadaddr    = ADFS_I(inode)->loadaddr;
 365         obj.execaddr    = ADFS_I(inode)->execaddr;
 366         obj.attr        = ADFS_I(inode)->attr;
 367         obj.size        = inode->i_size;
 368
 369         ret = adfs_dir_update(sb, &obj, wbc->sync_mode == WB_SYNC_ALL);
 370         return ret;
 371 }