fs/adfs/inode.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  linux/fs/adfs/inode.c
   4  *
   5  *  Copyright (C) 1997-1999 Russell King
   6  */
   7 #include <linux/buffer_head.h>
   8 #include <linux/writeback.h>
   9 #include "adfs.h"
  10
  11 /*
  12  * Lookup/Create a block at offset 'block' into 'inode'.  We currently do
  13  * not support creation of new blocks, so we return -EIO for this case.
  14  */
  15 static int
  16 adfs_get_block(struct inode *inode, sector_t block, struct buffer_head *bh,
  17                int create)
  18 {
  19         if (!create) {
  20                 if (block >= inode->i_blocks)
  21                         goto abort_toobig;
  22
  23                 block = __adfs_block_map(inode->i_sb, inode->i_ino, block);
  24                 if (block)
  25                         map_bh(bh, inode->i_sb, block);
  26                 return 0;
  27         }
  28         /* don't support allocation of blocks yet */
  29         return -EIO;
  30
  31 abort_toobig:
  32         return 0;
  33 }
  34
  35 static int adfs_writepage(struct page *page, struct writeback_control *wbc)
  36 {
  37         return block_write_full_page(page, adfs_get_block, wbc);
  38 }
  39
  40 static int adfs_readpage(struct file *file, struct page *page)
  41 {
  42         return block_read_full_page(page, adfs_get_block);
  43 }
  44
  45 static void adfs_write_failed(struct address_space *mapping, loff_t to)
  46 {
  47         struct inode *inode = mapping->host;
  48
  49         if (to > inode->i_size)
  50                 truncate_pagecache(inode, inode->i_size);
  51 }
  52
  53 static int adfs_write_begin(struct file *file, struct address_space *mapping,
  54                         loff_t pos, unsigned len, unsigned flags,
  55                         struct page **pagep, void **fsdata)
  56 {
  57         int ret;
  58
  59         *pagep = NULL;
  60         ret = cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
  61                                 adfs_get_block,
  62                                 &ADFS_I(mapping->host)->mmu_private);
  63         if (unlikely(ret))
  64                 adfs_write_failed(mapping, pos + len);
  65
  66         return ret;
  67 }
  68
  69 static sector_t _adfs_bmap(struct address_space *mapping, sector_t block)
  70 {
  71         return generic_block_bmap(mapping, block, adfs_get_block);
  72 }
  73
  74 static const struct address_space_operations adfs_aops = {
  75         .readpage       = adfs_readpage,
  76         .writepage      = adfs_writepage,
  77         .write_begin    = adfs_write_begin,
  78         .write_end      = generic_write_end,
  79         .bmap           = _adfs_bmap
  80 };
  81
  82 /*
  83  * Convert ADFS attributes and filetype to Linux permission.
  84  */
  85 static umode_t
  86 adfs_atts2mode(struct super_block *sb, struct inode *inode)
  87 {
  88         unsigned int attr = ADFS_I(inode)->attr;
  89         umode_t mode, rmask;
  90         struct adfs_sb_info *asb = ADFS_SB(sb);
  91
  92         if (attr & ADFS_NDA_DIRECTORY) {
  93                 mode = S_IRUGO & asb->s_owner_mask;
  94                 return S_IFDIR | S_IXUGO | mode;
  95         }
  96
  97         switch (adfs_filetype(ADFS_I(inode)->loadaddr)) {
  98         case 0xfc0:     /* LinkFS */
  99                 return S_IFLNK|S_IRWXUGO;
 100
 101         case 0xfe6:     /* UnixExec */
 102                 rmask = S_IRUGO | S_IXUGO;
 103                 break;
 104
 105         default:
 106                 rmask = S_IRUGO;
 107         }
 108
 109         mode = S_IFREG;
 110
 111         if (attr & ADFS_NDA_OWNER_READ)
 112                 mode |= rmask & asb->s_owner_mask;
 113
 114         if (attr & ADFS_NDA_OWNER_WRITE)
 115                 mode |= S_IWUGO & asb->s_owner_mask;
 116
 117         if (attr & ADFS_NDA_PUBLIC_READ)
 118                 mode |= rmask & asb->s_other_mask;
 119
 120         if (attr & ADFS_NDA_PUBLIC_WRITE)
 121                 mode |= S_IWUGO & asb->s_other_mask;
 122         return mode;
 123 }
 124
 125 /*
 126  * Convert Linux permission to ADFS attribute.  We try to do the reverse
 127  * of atts2mode, but there is not a 1:1 translation.
 128  */
 129 static int
 130 adfs_mode2atts(struct super_block *sb, struct inode *inode)
 131 {
 132         umode_t mode;
 133         int attr;
 134         struct adfs_sb_info *asb = ADFS_SB(sb);
 135
 136         /* FIXME: should we be able to alter a link? */
 137         if (S_ISLNK(inode->i_mode))
 138                 return ADFS_I(inode)->attr;
 139
 140         if (S_ISDIR(inode->i_mode))
 141                 attr = ADFS_NDA_DIRECTORY;
 142         else
 143                 attr = 0;
 144
 145         mode = inode->i_mode & asb->s_owner_mask;
 146         if (mode & S_IRUGO)
 147                 attr |= ADFS_NDA_OWNER_READ;
 148         if (mode & S_IWUGO)
 149                 attr |= ADFS_NDA_OWNER_WRITE;
 150
 151         mode = inode->i_mode & asb->s_other_mask;
 152         mode &= ~asb->s_owner_mask;
 153         if (mode & S_IRUGO)
 154                 attr |= ADFS_NDA_PUBLIC_READ;
 155         if (mode & S_IWUGO)
 156                 attr |= ADFS_NDA_PUBLIC_WRITE;
 157
 158         return attr;
 159 }
 160
 161 /*
 162  * Convert an ADFS time to Unix time.  ADFS has a 40-bit centi-second time
 163  * referenced to 1 Jan 1900 (til 2248) so we need to discard 2208988800 seconds
 164  * of time to convert from RISC OS epoch to Unix epoch.
 165  */
 166 static void
 167 adfs_adfs2unix_time(struct timespec64 *tv, struct inode *inode)
 168 {
 169         unsigned int high, low;
 170         /* 01 Jan 1970 00:00:00 (Unix epoch) as nanoseconds since
 171          * 01 Jan 1900 00:00:00 (RISC OS epoch)
 172          */
 173         static const s64 nsec_unix_epoch_diff_risc_os_epoch =
 174                                                         2208988800000000000LL;
 175         s64 nsec;
 176
 177         if (!adfs_inode_is_stamped(inode))
 178                 goto cur_time;
 179
 180         high = ADFS_I(inode)->loadaddr & 0xFF; /* top 8 bits of timestamp */
 181         low  = ADFS_I(inode)->execaddr;    /* bottom 32 bits of timestamp */
 182
 183         /* convert 40-bit centi-seconds to 32-bit seconds
 184          * going via nanoseconds to retain precision
 185          */
 186         nsec = (((s64) high << 32) | (s64) low) * 10000000; /* cs to ns */
 187
 188         /* Files dated pre  01 Jan 1970 00:00:00. */
 189         if (nsec < nsec_unix_epoch_diff_risc_os_epoch)
 190                 goto too_early;
 191
 192         /* convert from RISC OS to Unix epoch */
 193         nsec -= nsec_unix_epoch_diff_risc_os_epoch;
 194
 195         *tv = ns_to_timespec64(nsec);
 196         return;
 197
 198  cur_time:
 199         *tv = current_time(inode);
 200         return;
 201
 202  too_early:
 203         tv->tv_sec = tv->tv_nsec = 0;
 204         return;
 205 }
 206
 207 /*
 208  * Convert an Unix time to ADFS time.  We only do this if the entry has a
 209  * time/date stamp already.
 210  */
 211 static void
 212 adfs_unix2adfs_time(struct inode *inode, unsigned int secs)
 213 {
 214         unsigned int high, low;
 215
 216         if (adfs_inode_is_stamped(inode)) {
 217                 /* convert 32-bit seconds to 40-bit centi-seconds */
 218                 low  = (secs & 255) * 100;
 219                 high = (secs / 256) * 100 + (low >> 8) + 0x336e996a;
 220
 221                 ADFS_I(inode)->loadaddr = (high >> 24) |
 222                                 (ADFS_I(inode)->loadaddr & ~0xff);
 223                 ADFS_I(inode)->execaddr = (low & 255) | (high << 8);
 224         }
 225 }
 226
 227 /*
 228  * Fill in the inode information from the object information.
 229  *
 230  * Note that this is an inode-less filesystem, so we can't use the inode
 231  * number to reference the metadata on the media.  Instead, we use the
 232  * inode number to hold the object ID, which in turn will tell us where
 233  * the data is held.  We also save the parent object ID, and with these
 234  * two, we can locate the metadata.
 235  *
 236  * This does mean that we rely on an objects parent remaining the same at
 237  * all times - we cannot cope with a cross-directory rename (yet).
 238  */
 239 struct inode *
 240 adfs_iget(struct super_block *sb, struct object_info *obj)
 241 {
 242         struct inode *inode;
 243
 244         inode = new_inode(sb);
 245         if (!inode)
 246                 goto out;
 247
 248         inode->i_uid     = ADFS_SB(sb)->s_uid;
 249         inode->i_gid     = ADFS_SB(sb)->s_gid;
 250         inode->i_ino     = obj->indaddr;
 251         inode->i_size    = obj->size;
 252         set_nlink(inode, 2);
 253         inode->i_blocks  = (inode->i_size + sb->s_blocksize - 1) >>
 254                             sb->s_blocksize_bits;
 255
 256         /*
 257          * we need to save the parent directory ID so that
 258          * write_inode can update the directory information
 259          * for this file.  This will need special handling
 260          * for cross-directory renames.
 261          */
 262         ADFS_I(inode)->parent_id = obj->parent_id;
 263         ADFS_I(inode)->loadaddr  = obj->loadaddr;
 264         ADFS_I(inode)->execaddr  = obj->execaddr;
 265         ADFS_I(inode)->attr      = obj->attr;
 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         inode_fake_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 = d_inode(dentry);
 297         struct super_block *sb = inode->i_sb;
 298         unsigned int ia_valid = attr->ia_valid;
 299         int error;
 300
 301         error = setattr_prepare(dentry, 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 && !uid_eq(attr->ia_uid, ADFS_SB(sb)->s_uid)) ||
 308             (ia_valid & ATTR_GID && !gid_eq(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.indaddr     = 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 }