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