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 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, to, inode->i_size);
  54}
  55
  56static 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
  72static sector_t _adfs_bmap(struct address_space *mapping, sector_t block)
  73{
  74        return generic_block_bmap(mapping, block, adfs_get_block);
  75}
  76
  77static 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 */
  88static umode_t
  89adfs_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 */
 132static int
 133adfs_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 */
 169static void
 170adfs_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 */
 214static void
 215adfs_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 */
 242struct inode *
 243adfs_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
 289out:
 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 */
 298int
 299adfs_notify_change(struct dentry *dentry, struct iattr *attr)
 300{
 301        struct inode *inode = dentry->d_inode;
 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);
 346out:
 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 */
 355int 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}
 372
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