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         .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  */
  83 static umode_t
  84 adfs_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  */
 127 static int
 128 adfs_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  */
 164 static void
 165 adfs_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  */
 209 static void
 210 adfs_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  */
 237 struct inode *
 238 adfs_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
 284 out:
 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  */
 293 int
 294 adfs_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);
 341 out:
 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  */
 350 int 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 }