| 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_readpage(struct file *file, struct page *page) |
| 42 | { |
| 43 | return block_read_full_page(page, 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, unsigned flags, |
| 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 | .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 | */ |
| 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 | } |