linux/fs/adfs/inode.c
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   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 */
  18static int
  19adfs_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
  34abort_toobig:
  35        return 0;
  36}
  37
  38static int adfs_writepage(struct page *page, struct writeback_control *wbc)
  39{
  40        return block_write_full_page(page, adfs_get_block, wbc);
  41}
  42
  43static int adfs_readpage(struct file *file, struct page *page)
  44{
  45        return block_read_full_page(page, adfs_get_block);
  46}
  47
  48static 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
  67static sector_t _adfs_bmap(struct address_space *mapping, sector_t block)
  68{
  69        return generic_block_bmap(mapping, block, adfs_get_block);
  70}
  71
  72static const struct address_space_operations adfs_aops = {
  73        .readpage       = adfs_readpage,
  74        .writepage      = adfs_writepage,
  75        .write_begin    = adfs_write_begin,
  76        .write_end      = generic_write_end,
  77        .bmap           = _adfs_bmap
  78};
  79
  80/*
  81 * Convert ADFS attributes and filetype to Linux permission.
  82 */
  83static umode_t
  84adfs_atts2mode(struct super_block *sb, struct inode *inode)
  85{
  86        unsigned int attr = ADFS_I(inode)->attr;
  87        umode_t mode, rmask;
  88        struct adfs_sb_info *asb = ADFS_SB(sb);
  89
  90        if (attr & ADFS_NDA_DIRECTORY) {
  91                mode = S_IRUGO & asb->s_owner_mask;
  92                return S_IFDIR | S_IXUGO | mode;
  93        }
  94
  95        switch (ADFS_I(inode)->filetype) {
  96        case 0xfc0:     /* LinkFS */
  97                return S_IFLNK|S_IRWXUGO;
  98
  99        case 0xfe6:     /* UnixExec */
 100                rmask = S_IRUGO | S_IXUGO;
 101                break;
 102
 103        default:
 104                rmask = S_IRUGO;
 105        }
 106
 107        mode = S_IFREG;
 108
 109        if (attr & ADFS_NDA_OWNER_READ)
 110                mode |= rmask & asb->s_owner_mask;
 111
 112        if (attr & ADFS_NDA_OWNER_WRITE)
 113                mode |= S_IWUGO & asb->s_owner_mask;
 114
 115        if (attr & ADFS_NDA_PUBLIC_READ)
 116                mode |= rmask & asb->s_other_mask;
 117
 118        if (attr & ADFS_NDA_PUBLIC_WRITE)
 119                mode |= S_IWUGO & asb->s_other_mask;
 120        return mode;
 121}
 122
 123/*
 124 * Convert Linux permission to ADFS attribute.  We try to do the reverse
 125 * of atts2mode, but there is not a 1:1 translation.
 126 */
 127static int
 128adfs_mode2atts(struct super_block *sb, struct inode *inode)
 129{
 130        umode_t mode;
 131        int attr;
 132        struct adfs_sb_info *asb = ADFS_SB(sb);
 133
 134        /* FIXME: should we be able to alter a link? */
 135        if (S_ISLNK(inode->i_mode))
 136                return ADFS_I(inode)->attr;
 137
 138        if (S_ISDIR(inode->i_mode))
 139                attr = ADFS_NDA_DIRECTORY;
 140        else
 141                attr = 0;
 142
 143        mode = inode->i_mode & asb->s_owner_mask;
 144        if (mode & S_IRUGO)
 145                attr |= ADFS_NDA_OWNER_READ;
 146        if (mode & S_IWUGO)
 147                attr |= ADFS_NDA_OWNER_WRITE;
 148
 149        mode = inode->i_mode & asb->s_other_mask;
 150        mode &= ~asb->s_owner_mask;
 151        if (mode & S_IRUGO)
 152                attr |= ADFS_NDA_PUBLIC_READ;
 153        if (mode & S_IWUGO)
 154                attr |= ADFS_NDA_PUBLIC_WRITE;
 155
 156        return attr;
 157}
 158
 159/*
 160 * Convert an ADFS time to Unix time.  ADFS has a 40-bit centi-second time
 161 * referenced to 1 Jan 1900 (til 2248) so we need to discard 2208988800 seconds
 162 * of time to convert from RISC OS epoch to Unix epoch.
 163 */
 164static void
 165adfs_adfs2unix_time(struct timespec *tv, struct inode *inode)
 166{
 167        unsigned int high, low;
 168        /* 01 Jan 1970 00:00:00 (Unix epoch) as nanoseconds since
 169         * 01 Jan 1900 00:00:00 (RISC OS epoch)
 170         */
 171        static const s64 nsec_unix_epoch_diff_risc_os_epoch =
 172                                                        2208988800000000000LL;
 173        s64 nsec;
 174
 175        if (ADFS_I(inode)->stamped == 0)
 176                goto cur_time;
 177
 178        high = ADFS_I(inode)->loadaddr & 0xFF; /* top 8 bits of timestamp */
 179        low  = ADFS_I(inode)->execaddr;    /* bottom 32 bits of timestamp */
 180
 181        /* convert 40-bit centi-seconds to 32-bit seconds
 182         * going via nanoseconds to retain precision
 183         */
 184        nsec = (((s64) high << 32) | (s64) low) * 10000000; /* cs to ns */
 185
 186        /* Files dated pre  01 Jan 1970 00:00:00. */
 187        if (nsec < nsec_unix_epoch_diff_risc_os_epoch)
 188                goto too_early;
 189
 190        /* convert from RISC OS to Unix epoch */
 191        nsec -= nsec_unix_epoch_diff_risc_os_epoch;
 192
 193        *tv = ns_to_timespec(nsec);
 194        return;
 195
 196 cur_time:
 197        *tv = CURRENT_TIME;
 198        return;
 199
 200 too_early:
 201        tv->tv_sec = tv->tv_nsec = 0;
 202        return;
 203}
 204
 205/*
 206 * Convert an Unix time to ADFS time.  We only do this if the entry has a
 207 * time/date stamp already.
 208 */
 209static void
 210adfs_unix2adfs_time(struct inode *inode, unsigned int secs)
 211{
 212        unsigned int high, low;
 213
 214        if (ADFS_I(inode)->stamped) {
 215                /* convert 32-bit seconds to 40-bit centi-seconds */
 216                low  = (secs & 255) * 100;
 217                high = (secs / 256) * 100 + (low >> 8) + 0x336e996a;
 218
 219                ADFS_I(inode)->loadaddr = (high >> 24) |
 220                                (ADFS_I(inode)->loadaddr & ~0xff);
 221                ADFS_I(inode)->execaddr = (low & 255) | (high << 8);
 222        }
 223}
 224
 225/*
 226 * Fill in the inode information from the object information.
 227 *
 228 * Note that this is an inode-less filesystem, so we can't use the inode
 229 * number to reference the metadata on the media.  Instead, we use the
 230 * inode number to hold the object ID, which in turn will tell us where
 231 * the data is held.  We also save the parent object ID, and with these
 232 * two, we can locate the metadata.
 233 *
 234 * This does mean that we rely on an objects parent remaining the same at
 235 * all times - we cannot cope with a cross-directory rename (yet).
 236 */
 237struct inode *
 238adfs_iget(struct super_block *sb, struct object_info *obj)
 239{
 240        struct inode *inode;
 241
 242        inode = new_inode(sb);
 243        if (!inode)
 244                goto out;
 245
 246        inode->i_uid     = ADFS_SB(sb)->s_uid;
 247        inode->i_gid     = ADFS_SB(sb)->s_gid;
 248        inode->i_ino     = obj->file_id;
 249        inode->i_size    = obj->size;
 250        set_nlink(inode, 2);
 251        inode->i_blocks  = (inode->i_size + sb->s_blocksize - 1) >>
 252                            sb->s_blocksize_bits;
 253
 254        /*
 255         * we need to save the parent directory ID so that
 256         * write_inode can update the directory information
 257         * for this file.  This will need special handling
 258         * for cross-directory renames.
 259         */
 260        ADFS_I(inode)->parent_id = obj->parent_id;
 261        ADFS_I(inode)->loadaddr  = obj->loadaddr;
 262        ADFS_I(inode)->execaddr  = obj->execaddr;
 263        ADFS_I(inode)->attr      = obj->attr;
 264        ADFS_I(inode)->filetype  = obj->filetype;
 265        ADFS_I(inode)->stamped   = ((obj->loadaddr & 0xfff00000) == 0xfff00000);
 266
 267        inode->i_mode    = adfs_atts2mode(sb, inode);
 268        adfs_adfs2unix_time(&inode->i_mtime, inode);
 269        inode->i_atime = inode->i_mtime;
 270        inode->i_ctime = inode->i_mtime;
 271
 272        if (S_ISDIR(inode->i_mode)) {
 273                inode->i_op     = &adfs_dir_inode_operations;
 274                inode->i_fop    = &adfs_dir_operations;
 275        } else if (S_ISREG(inode->i_mode)) {
 276                inode->i_op     = &adfs_file_inode_operations;
 277                inode->i_fop    = &adfs_file_operations;
 278                inode->i_mapping->a_ops = &adfs_aops;
 279                ADFS_I(inode)->mmu_private = inode->i_size;
 280        }
 281
 282        insert_inode_hash(inode);
 283
 284out:
 285        return inode;
 286}
 287
 288/*
 289 * Validate and convert a changed access mode/time to their ADFS equivalents.
 290 * adfs_write_inode will actually write the information back to the directory
 291 * later.
 292 */
 293int
 294adfs_notify_change(struct dentry *dentry, struct iattr *attr)
 295{
 296        struct inode *inode = dentry->d_inode;
 297        struct super_block *sb = inode->i_sb;
 298        unsigned int ia_valid = attr->ia_valid;
 299        int error;
 300        
 301        error = inode_change_ok(inode, attr);
 302
 303        /*
 304         * we can't change the UID or GID of any file -
 305         * we have a global UID/GID in the superblock
 306         */
 307        if ((ia_valid & ATTR_UID && attr->ia_uid != ADFS_SB(sb)->s_uid) ||
 308            (ia_valid & ATTR_GID && attr->ia_gid != ADFS_SB(sb)->s_gid))
 309                error = -EPERM;
 310
 311        if (error)
 312                goto out;
 313
 314        /* XXX: this is missing some actual on-disk truncation.. */
 315        if (ia_valid & ATTR_SIZE)
 316                truncate_setsize(inode, attr->ia_size);
 317
 318        if (ia_valid & ATTR_MTIME) {
 319                inode->i_mtime = attr->ia_mtime;
 320                adfs_unix2adfs_time(inode, attr->ia_mtime.tv_sec);
 321        }
 322        /*
 323         * FIXME: should we make these == to i_mtime since we don't
 324         * have the ability to represent them in our filesystem?
 325         */
 326        if (ia_valid & ATTR_ATIME)
 327                inode->i_atime = attr->ia_atime;
 328        if (ia_valid & ATTR_CTIME)
 329                inode->i_ctime = attr->ia_ctime;
 330        if (ia_valid & ATTR_MODE) {
 331                ADFS_I(inode)->attr = adfs_mode2atts(sb, inode);
 332                inode->i_mode = adfs_atts2mode(sb, inode);
 333        }
 334
 335        /*
 336         * FIXME: should we be marking this inode dirty even if
 337         * we don't have any metadata to write back?
 338         */
 339        if (ia_valid & (ATTR_SIZE | ATTR_MTIME | ATTR_MODE))
 340                mark_inode_dirty(inode);
 341out:
 342        return error;
 343}
 344
 345/*
 346 * write an existing inode back to the directory, and therefore the disk.
 347 * The adfs-specific inode data has already been updated by
 348 * adfs_notify_change()
 349 */
 350int adfs_write_inode(struct inode *inode, struct writeback_control *wbc)
 351{
 352        struct super_block *sb = inode->i_sb;
 353        struct object_info obj;
 354        int ret;
 355
 356        obj.file_id     = inode->i_ino;
 357        obj.name_len    = 0;
 358        obj.parent_id   = ADFS_I(inode)->parent_id;
 359        obj.loadaddr    = ADFS_I(inode)->loadaddr;
 360        obj.execaddr    = ADFS_I(inode)->execaddr;
 361        obj.attr        = ADFS_I(inode)->attr;
 362        obj.size        = inode->i_size;
 363
 364        ret = adfs_dir_update(sb, &obj, wbc->sync_mode == WB_SYNC_ALL);
 365        return ret;
 366}
 367
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