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, ADFS_I(inode)->indaddr,
  24                                          block);
  25                 if (block)
  26                         map_bh(bh, inode->i_sb, block);
  27                 return 0;
  28         }
  29         /* don't support allocation of blocks yet */
  30         return -EIO;
  31
  32 abort_toobig:
  33         return 0;
  34 }
  35
  36 static int adfs_writepage(struct page *page, struct writeback_control *wbc)
  37 {
  38         return block_write_full_page(page, adfs_get_block, wbc);
  39 }
  40
  41 static int adfs_read_folio(struct file *file, struct folio *folio)
  42 {
  43         return block_read_full_folio(folio, adfs_get_block);
  44 }
  45
  46 static void adfs_write_failed(struct address_space *mapping, loff_t to)
  47 {
  48         struct inode *inode = mapping->host;
  49
  50         if (to > inode->i_size)
  51                 truncate_pagecache(inode, inode->i_size);
  52 }
  53
  54 static int adfs_write_begin(struct file *file, struct address_space *mapping,
  55                         loff_t pos, unsigned len,
  56                         struct page **pagep, void **fsdata)
  57 {
  58         int ret;
  59
  60         *pagep = NULL;
  61         ret = cont_write_begin(file, mapping, pos, len, pagep, fsdata,
  62                                 adfs_get_block,
  63                                 &ADFS_I(mapping->host)->mmu_private);
  64         if (unlikely(ret))
  65                 adfs_write_failed(mapping, pos + len);
  66
  67         return ret;
  68 }
  69
  70 static sector_t _adfs_bmap(struct address_space *mapping, sector_t block)
  71 {
  72         return generic_block_bmap(mapping, block, adfs_get_block);
  73 }
  74
  75 static const struct address_space_operations adfs_aops = {
  76         .dirty_folio    = block_dirty_folio,
  77         .invalidate_folio = block_invalidate_folio,
  78         .read_folio     = adfs_read_folio,
  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  */
  88 static umode_t
  89 adfs_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_filetype(ADFS_I(inode)->loadaddr)) {
 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  */
 132 static int adfs_mode2atts(struct super_block *sb, struct inode *inode,
 133                           umode_t ia_mode)
 134 {
 135         struct adfs_sb_info *asb = ADFS_SB(sb);
 136         umode_t mode;
 137         int attr;
 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         /* Directories do not have read/write permissions on the media */
 144         if (S_ISDIR(inode->i_mode))
 145                 return ADFS_NDA_DIRECTORY;
 146
 147         attr = 0;
 148         mode = ia_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 = ia_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 static const s64 nsec_unix_epoch_diff_risc_os_epoch = 2208988800000000000LL;
 165
 166 /*
 167  * Convert an ADFS time to Unix time.  ADFS has a 40-bit centi-second time
 168  * referenced to 1 Jan 1900 (til 2248) so we need to discard 2208988800 seconds
 169  * of time to convert from RISC OS epoch to Unix epoch.
 170  */
 171 static void
 172 adfs_adfs2unix_time(struct timespec64 *tv, struct inode *inode)
 173 {
 174         unsigned int high, low;
 175         /* 01 Jan 1970 00:00:00 (Unix epoch) as nanoseconds since
 176          * 01 Jan 1900 00:00:00 (RISC OS epoch)
 177          */
 178         s64 nsec;
 179
 180         if (!adfs_inode_is_stamped(inode))
 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_timespec64(nsec);
 199         return;
 200
 201  cur_time:
 202         *tv = current_time(inode);
 203         return;
 204
 205  too_early:
 206         tv->tv_sec = tv->tv_nsec = 0;
 207         return;
 208 }
 209
 210 /* Convert an Unix time to ADFS time for an entry that is already stamped. */
 211 static void adfs_unix2adfs_time(struct inode *inode,
 212                                 const struct timespec64 *ts)
 213 {
 214         s64 cs, nsec = timespec64_to_ns(ts);
 215
 216         /* convert from Unix to RISC OS epoch */
 217         nsec += nsec_unix_epoch_diff_risc_os_epoch;
 218
 219         /* convert from nanoseconds to centiseconds */
 220         cs = div_s64(nsec, 10000000);
 221
 222         cs = clamp_t(s64, cs, 0, 0xffffffffff);
 223
 224         ADFS_I(inode)->loadaddr &= ~0xff;
 225         ADFS_I(inode)->loadaddr |= (cs >> 32) & 0xff;
 226         ADFS_I(inode)->execaddr = cs;
 227 }
 228
 229 /*
 230  * Fill in the inode information from the object information.
 231  *
 232  * Note that this is an inode-less filesystem, so we can't use the inode
 233  * number to reference the metadata on the media.  Instead, we use the
 234  * inode number to hold the object ID, which in turn will tell us where
 235  * the data is held.  We also save the parent object ID, and with these
 236  * two, we can locate the metadata.
 237  *
 238  * This does mean that we rely on an objects parent remaining the same at
 239  * all times - we cannot cope with a cross-directory rename (yet).
 240  */
 241 struct inode *
 242 adfs_iget(struct super_block *sb, struct object_info *obj)
 243 {
 244         struct inode *inode;
 245
 246         inode = new_inode(sb);
 247         if (!inode)
 248                 goto out;
 249
 250         inode->i_uid     = ADFS_SB(sb)->s_uid;
 251         inode->i_gid     = ADFS_SB(sb)->s_gid;
 252         inode->i_ino     = obj->indaddr;
 253         inode->i_size    = obj->size;
 254         set_nlink(inode, 2);
 255         inode->i_blocks  = (inode->i_size + sb->s_blocksize - 1) >>
 256                             sb->s_blocksize_bits;
 257
 258         /*
 259          * we need to save the parent directory ID so that
 260          * write_inode can update the directory information
 261          * for this file.  This will need special handling
 262          * for cross-directory renames.
 263          */
 264         ADFS_I(inode)->parent_id = obj->parent_id;
 265         ADFS_I(inode)->indaddr   = obj->indaddr;
 266         ADFS_I(inode)->loadaddr  = obj->loadaddr;
 267         ADFS_I(inode)->execaddr  = obj->execaddr;
 268         ADFS_I(inode)->attr      = obj->attr;
 269
 270         inode->i_mode    = adfs_atts2mode(sb, inode);
 271         adfs_adfs2unix_time(&inode->i_mtime, inode);
 272         inode->i_atime = inode->i_mtime;
 273         inode->i_ctime = inode->i_mtime;
 274
 275         if (S_ISDIR(inode->i_mode)) {
 276                 inode->i_op     = &adfs_dir_inode_operations;
 277                 inode->i_fop    = &adfs_dir_operations;
 278         } else if (S_ISREG(inode->i_mode)) {
 279                 inode->i_op     = &adfs_file_inode_operations;
 280                 inode->i_fop    = &adfs_file_operations;
 281                 inode->i_mapping->a_ops = &adfs_aops;
 282                 ADFS_I(inode)->mmu_private = inode->i_size;
 283         }
 284
 285         inode_fake_hash(inode);
 286
 287 out:
 288         return inode;
 289 }
 290
 291 /*
 292  * Validate and convert a changed access mode/time to their ADFS equivalents.
 293  * adfs_write_inode will actually write the information back to the directory
 294  * later.
 295  */
 296 int
 297 adfs_notify_change(struct user_namespace *mnt_userns, struct dentry *dentry,
 298                    struct iattr *attr)
 299 {
 300         struct inode *inode = d_inode(dentry);
 301         struct super_block *sb = inode->i_sb;
 302         unsigned int ia_valid = attr->ia_valid;
 303         int error;
 304
 305         error = setattr_prepare(&init_user_ns, dentry, attr);
 306
 307         /*
 308          * we can't change the UID or GID of any file -
 309          * we have a global UID/GID in the superblock
 310          */
 311         if ((ia_valid & ATTR_UID && !uid_eq(attr->ia_uid, ADFS_SB(sb)->s_uid)) ||
 312             (ia_valid & ATTR_GID && !gid_eq(attr->ia_gid, ADFS_SB(sb)->s_gid)))
 313                 error = -EPERM;
 314
 315         if (error)
 316                 goto out;
 317
 318         /* XXX: this is missing some actual on-disk truncation.. */
 319         if (ia_valid & ATTR_SIZE)
 320                 truncate_setsize(inode, attr->ia_size);
 321
 322         if (ia_valid & ATTR_MTIME && adfs_inode_is_stamped(inode)) {
 323                 adfs_unix2adfs_time(inode, &attr->ia_mtime);
 324                 adfs_adfs2unix_time(&inode->i_mtime, inode);
 325         }
 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, attr->ia_mode);
 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);
 346 out:
 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  */
 355 int 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
 360         obj.indaddr     = ADFS_I(inode)->indaddr;
 361         obj.name_len    = 0;
 362         obj.parent_id   = ADFS_I(inode)->parent_id;
 363         obj.loadaddr    = ADFS_I(inode)->loadaddr;
 364         obj.execaddr    = ADFS_I(inode)->execaddr;
 365         obj.attr        = ADFS_I(inode)->attr;
 366         obj.size        = inode->i_size;
 367
 368         return adfs_dir_update(sb, &obj, wbc->sync_mode == WB_SYNC_ALL);
 369 }