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/mpage.h> 9 #include <linux/writeback.h> 10 #include "adfs.h" 11 12 /* 13 * Lookup/Create a block at offset 'block' into 'inode'. We currently do 14 * not support creation of new blocks, so we return -EIO for this case. 15 */ 16 static int 17 adfs_get_block(struct inode *inode, sector_t block, struct buffer_head *bh, 18 int create) 19 { 20 if (!create) { 21 if (block >= inode->i_blocks) 22 goto abort_toobig; 23 24 block = __adfs_block_map(inode->i_sb, ADFS_I(inode)->indaddr, 25 block); 26 if (block) 27 map_bh(bh, inode->i_sb, block); 28 return 0; 29 } 30 /* don't support allocation of blocks yet */ 31 return -EIO; 32 33 abort_toobig: 34 return 0; 35 } 36 37 static int adfs_writepages(struct address_space *mapping, 38 struct writeback_control *wbc) 39 { 40 return mpage_writepages(mapping, wbc, adfs_get_block); 41 } 42 43 static int adfs_read_folio(struct file *file, struct folio *folio) 44 { 45 return block_read_full_folio(folio, adfs_get_block); 46 } 47 48 static void adfs_write_failed(struct address_space *mapping, loff_t to) 49 { 50 struct inode *inode = mapping->host; 51 52 if (to > inode->i_size) 53 truncate_pagecache(inode, inode->i_size); 54 } 55 56 static int adfs_write_begin(struct file *file, struct address_space *mapping, 57 loff_t pos, unsigned len, 58 struct folio **foliop, void **fsdata) 59 { 60 int ret; 61 62 ret = cont_write_begin(file, mapping, pos, len, foliop, fsdata, 63 adfs_get_block, 64 &ADFS_I(mapping->host)->mmu_private); 65 if (unlikely(ret)) 66 adfs_write_failed(mapping, pos + len); 67 68 return ret; 69 } 70 71 static sector_t _adfs_bmap(struct address_space *mapping, sector_t block) 72 { 73 return generic_block_bmap(mapping, block, adfs_get_block); 74 } 75 76 static const struct address_space_operations adfs_aops = { 77 .dirty_folio = block_dirty_folio, 78 .invalidate_folio = block_invalidate_folio, 79 .read_folio = adfs_read_folio, 80 .writepages = adfs_writepages, 81 .write_begin = adfs_write_begin, 82 .write_end = generic_write_end, 83 .migrate_folio = buffer_migrate_folio, 84 .bmap = _adfs_bmap, 85 }; 86 87 /* 88 * Convert ADFS attributes and filetype to Linux permission. 89 */ 90 static umode_t 91 adfs_atts2mode(struct super_block *sb, struct inode *inode) 92 { 93 unsigned int attr = ADFS_I(inode)->attr; 94 umode_t mode, rmask; 95 struct adfs_sb_info *asb = ADFS_SB(sb); 96 97 if (attr & ADFS_NDA_DIRECTORY) { 98 mode = S_IRUGO & asb->s_owner_mask; 99 return S_IFDIR | S_IXUGO | mode; 100 } 101 102 switch (adfs_filetype(ADFS_I(inode)->loadaddr)) { 103 case 0xfc0: /* LinkFS */ 104 return S_IFLNK|S_IRWXUGO; 105 106 case 0xfe6: /* UnixExec */ 107 rmask = S_IRUGO | S_IXUGO; 108 break; 109 110 default: 111 rmask = S_IRUGO; 112 } 113 114 mode = S_IFREG; 115 116 if (attr & ADFS_NDA_OWNER_READ) 117 mode |= rmask & asb->s_owner_mask; 118 119 if (attr & ADFS_NDA_OWNER_WRITE) 120 mode |= S_IWUGO & asb->s_owner_mask; 121 122 if (attr & ADFS_NDA_PUBLIC_READ) 123 mode |= rmask & asb->s_other_mask; 124 125 if (attr & ADFS_NDA_PUBLIC_WRITE) 126 mode |= S_IWUGO & asb->s_other_mask; 127 return mode; 128 } 129 130 /* 131 * Convert Linux permission to ADFS attribute. We try to do the reverse 132 * of atts2mode, but there is not a 1:1 translation. 133 */ 134 static int adfs_mode2atts(struct super_block *sb, struct inode *inode, 135 umode_t ia_mode) 136 { 137 struct adfs_sb_info *asb = ADFS_SB(sb); 138 umode_t mode; 139 int attr; 140 141 /* FIXME: should we be able to alter a link? */ 142 if (S_ISLNK(inode->i_mode)) 143 return ADFS_I(inode)->attr; 144 145 /* Directories do not have read/write permissions on the media */ 146 if (S_ISDIR(inode->i_mode)) 147 return ADFS_NDA_DIRECTORY; 148 149 attr = 0; 150 mode = ia_mode & asb->s_owner_mask; 151 if (mode & S_IRUGO) 152 attr |= ADFS_NDA_OWNER_READ; 153 if (mode & S_IWUGO) 154 attr |= ADFS_NDA_OWNER_WRITE; 155 156 mode = ia_mode & asb->s_other_mask; 157 mode &= ~asb->s_owner_mask; 158 if (mode & S_IRUGO) 159 attr |= ADFS_NDA_PUBLIC_READ; 160 if (mode & S_IWUGO) 161 attr |= ADFS_NDA_PUBLIC_WRITE; 162 163 return attr; 164 } 165 166 static const s64 nsec_unix_epoch_diff_risc_os_epoch = 2208988800000000000LL; 167 168 /* 169 * Convert an ADFS time to Unix time. ADFS has a 40-bit centi-second time 170 * referenced to 1 Jan 1900 (til 2248) so we need to discard 2208988800 seconds 171 * of time to convert from RISC OS epoch to Unix epoch. 172 */ 173 static void 174 adfs_adfs2unix_time(struct timespec64 *tv, struct inode *inode) 175 { 176 unsigned int high, low; 177 /* 01 Jan 1970 00:00:00 (Unix epoch) as nanoseconds since 178 * 01 Jan 1900 00:00:00 (RISC OS epoch) 179 */ 180 s64 nsec; 181 182 if (!adfs_inode_is_stamped(inode)) 183 goto cur_time; 184 185 high = ADFS_I(inode)->loadaddr & 0xFF; /* top 8 bits of timestamp */ 186 low = ADFS_I(inode)->execaddr; /* bottom 32 bits of timestamp */ 187 188 /* convert 40-bit centi-seconds to 32-bit seconds 189 * going via nanoseconds to retain precision 190 */ 191 nsec = (((s64) high << 32) | (s64) low) * 10000000; /* cs to ns */ 192 193 /* Files dated pre 01 Jan 1970 00:00:00. */ 194 if (nsec < nsec_unix_epoch_diff_risc_os_epoch) 195 goto too_early; 196 197 /* convert from RISC OS to Unix epoch */ 198 nsec -= nsec_unix_epoch_diff_risc_os_epoch; 199 200 *tv = ns_to_timespec64(nsec); 201 return; 202 203 cur_time: 204 *tv = current_time(inode); 205 return; 206 207 too_early: 208 tv->tv_sec = tv->tv_nsec = 0; 209 return; 210 } 211 212 /* Convert an Unix time to ADFS time for an entry that is already stamped. */ 213 static void adfs_unix2adfs_time(struct inode *inode, 214 const struct timespec64 *ts) 215 { 216 s64 cs, nsec = timespec64_to_ns(ts); 217 218 /* convert from Unix to RISC OS epoch */ 219 nsec += nsec_unix_epoch_diff_risc_os_epoch; 220 221 /* convert from nanoseconds to centiseconds */ 222 cs = div_s64(nsec, 10000000); 223 224 cs = clamp_t(s64, cs, 0, 0xffffffffff); 225 226 ADFS_I(inode)->loadaddr &= ~0xff; 227 ADFS_I(inode)->loadaddr |= (cs >> 32) & 0xff; 228 ADFS_I(inode)->execaddr = cs; 229 } 230 231 /* 232 * Fill in the inode information from the object information. 233 * 234 * Note that this is an inode-less filesystem, so we can't use the inode 235 * number to reference the metadata on the media. Instead, we use the 236 * inode number to hold the object ID, which in turn will tell us where 237 * the data is held. We also save the parent object ID, and with these 238 * two, we can locate the metadata. 239 * 240 * This does mean that we rely on an objects parent remaining the same at 241 * all times - we cannot cope with a cross-directory rename (yet). 242 */ 243 struct inode * 244 adfs_iget(struct super_block *sb, struct object_info *obj) 245 { 246 struct inode *inode; 247 struct timespec64 ts; 248 249 inode = new_inode(sb); 250 if (!inode) 251 goto out; 252 253 inode->i_uid = ADFS_SB(sb)->s_uid; 254 inode->i_gid = ADFS_SB(sb)->s_gid; 255 inode->i_ino = obj->indaddr; 256 inode->i_size = obj->size; 257 set_nlink(inode, 2); 258 inode->i_blocks = (inode->i_size + sb->s_blocksize - 1) >> 259 sb->s_blocksize_bits; 260 261 /* 262 * we need to save the parent directory ID so that 263 * write_inode can update the directory information 264 * for this file. This will need special handling 265 * for cross-directory renames. 266 */ 267 ADFS_I(inode)->parent_id = obj->parent_id; 268 ADFS_I(inode)->indaddr = obj->indaddr; 269 ADFS_I(inode)->loadaddr = obj->loadaddr; 270 ADFS_I(inode)->execaddr = obj->execaddr; 271 ADFS_I(inode)->attr = obj->attr; 272 273 inode->i_mode = adfs_atts2mode(sb, inode); 274 adfs_adfs2unix_time(&ts, inode); 275 inode_set_atime_to_ts(inode, ts); 276 inode_set_mtime_to_ts(inode, ts); 277 inode_set_ctime_to_ts(inode, ts); 278 279 if (S_ISDIR(inode->i_mode)) { 280 inode->i_op = &adfs_dir_inode_operations; 281 inode->i_fop = &adfs_dir_operations; 282 } else if (S_ISREG(inode->i_mode)) { 283 inode->i_op = &adfs_file_inode_operations; 284 inode->i_fop = &adfs_file_operations; 285 inode->i_mapping->a_ops = &adfs_aops; 286 ADFS_I(inode)->mmu_private = inode->i_size; 287 } 288 289 inode_fake_hash(inode); 290 291 out: 292 return inode; 293 } 294 295 /* 296 * Validate and convert a changed access mode/time to their ADFS equivalents. 297 * adfs_write_inode will actually write the information back to the directory 298 * later. 299 */ 300 int 301 adfs_notify_change(struct mnt_idmap *idmap, struct dentry *dentry, 302 struct iattr *attr) 303 { 304 struct inode *inode = d_inode(dentry); 305 struct super_block *sb = inode->i_sb; 306 unsigned int ia_valid = attr->ia_valid; 307 int error; 308 309 error = setattr_prepare(&nop_mnt_idmap, dentry, attr); 310 311 /* 312 * we can't change the UID or GID of any file - 313 * we have a global UID/GID in the superblock 314 */ 315 if ((ia_valid & ATTR_UID && !uid_eq(attr->ia_uid, ADFS_SB(sb)->s_uid)) || 316 (ia_valid & ATTR_GID && !gid_eq(attr->ia_gid, ADFS_SB(sb)->s_gid))) 317 error = -EPERM; 318 319 if (error) 320 goto out; 321 322 /* XXX: this is missing some actual on-disk truncation.. */ 323 if (ia_valid & ATTR_SIZE) 324 truncate_setsize(inode, attr->ia_size); 325 326 if (ia_valid & ATTR_MTIME && adfs_inode_is_stamped(inode)) { 327 adfs_unix2adfs_time(inode, &attr->ia_mtime); 328 adfs_adfs2unix_time(&attr->ia_mtime, inode); 329 inode_set_mtime_to_ts(inode, attr->ia_mtime); 330 } 331 332 /* 333 * FIXME: should we make these == to i_mtime since we don't 334 * have the ability to represent them in our filesystem? 335 */ 336 if (ia_valid & ATTR_ATIME) 337 inode_set_atime_to_ts(inode, attr->ia_atime); 338 if (ia_valid & ATTR_CTIME) 339 inode_set_ctime_to_ts(inode, attr->ia_ctime); 340 if (ia_valid & ATTR_MODE) { 341 ADFS_I(inode)->attr = adfs_mode2atts(sb, inode, attr->ia_mode); 342 inode->i_mode = adfs_atts2mode(sb, inode); 343 } 344 345 /* 346 * FIXME: should we be marking this inode dirty even if 347 * we don't have any metadata to write back? 348 */ 349 if (ia_valid & (ATTR_SIZE | ATTR_MTIME | ATTR_MODE)) 350 mark_inode_dirty(inode); 351 out: 352 return error; 353 } 354 355 /* 356 * write an existing inode back to the directory, and therefore the disk. 357 * The adfs-specific inode data has already been updated by 358 * adfs_notify_change() 359 */ 360 int adfs_write_inode(struct inode *inode, struct writeback_control *wbc) 361 { 362 struct super_block *sb = inode->i_sb; 363 struct object_info obj; 364 365 obj.indaddr = ADFS_I(inode)->indaddr; 366 obj.name_len = 0; 367 obj.parent_id = ADFS_I(inode)->parent_id; 368 obj.loadaddr = ADFS_I(inode)->loadaddr; 369 obj.execaddr = ADFS_I(inode)->execaddr; 370 obj.attr = ADFS_I(inode)->attr; 371 obj.size = inode->i_size; 372 373 return adfs_dir_update(sb, &obj, wbc->sync_mode == WB_SYNC_ALL); 374 } 375