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 page **pagep, void **fsdata) 59 { 60 int ret; 61 62 *pagep = NULL; 63 ret = cont_write_begin(file, mapping, pos, len, pagep, fsdata, 64 adfs_get_block, 65 &ADFS_I(mapping->host)->mmu_private); 66 if (unlikely(ret)) 67 adfs_write_failed(mapping, pos + len); 68 69 return ret; 70 } 71 72 static sector_t _adfs_bmap(struct address_space *mapping, sector_t block) 73 { 74 return generic_block_bmap(mapping, block, adfs_get_block); 75 } 76 77 static const struct address_space_operations adfs_aops = { 78 .dirty_folio = block_dirty_folio, 79 .invalidate_folio = block_invalidate_folio, 80 .read_folio = adfs_read_folio, 81 .writepages = adfs_writepages, 82 .write_begin = adfs_write_begin, 83 .write_end = generic_write_end, 84 .migrate_folio = buffer_migrate_folio, 85 .bmap = _adfs_bmap, 86 }; 87 88 /* 89 * Convert ADFS attributes and filetype to Linux permission. 90 */ 91 static umode_t 92 adfs_atts2mode(struct super_block *sb, struct inode *inode) 93 { 94 unsigned int attr = ADFS_I(inode)->attr; 95 umode_t mode, rmask; 96 struct adfs_sb_info *asb = ADFS_SB(sb); 97 98 if (attr & ADFS_NDA_DIRECTORY) { 99 mode = S_IRUGO & asb->s_owner_mask; 100 return S_IFDIR | S_IXUGO | mode; 101 } 102 103 switch (adfs_filetype(ADFS_I(inode)->loadaddr)) { 104 case 0xfc0: /* LinkFS */ 105 return S_IFLNK|S_IRWXUGO; 106 107 case 0xfe6: /* UnixExec */ 108 rmask = S_IRUGO | S_IXUGO; 109 break; 110 111 default: 112 rmask = S_IRUGO; 113 } 114 115 mode = S_IFREG; 116 117 if (attr & ADFS_NDA_OWNER_READ) 118 mode |= rmask & asb->s_owner_mask; 119 120 if (attr & ADFS_NDA_OWNER_WRITE) 121 mode |= S_IWUGO & asb->s_owner_mask; 122 123 if (attr & ADFS_NDA_PUBLIC_READ) 124 mode |= rmask & asb->s_other_mask; 125 126 if (attr & ADFS_NDA_PUBLIC_WRITE) 127 mode |= S_IWUGO & asb->s_other_mask; 128 return mode; 129 } 130 131 /* 132 * Convert Linux permission to ADFS attribute. We try to do the reverse 133 * of atts2mode, but there is not a 1:1 translation. 134 */ 135 static int adfs_mode2atts(struct super_block *sb, struct inode *inode, 136 umode_t ia_mode) 137 { 138 struct adfs_sb_info *asb = ADFS_SB(sb); 139 umode_t mode; 140 int attr; 141 142 /* FIXME: should we be able to alter a link? */ 143 if (S_ISLNK(inode->i_mode)) 144 return ADFS_I(inode)->attr; 145 146 /* Directories do not have read/write permissions on the media */ 147 if (S_ISDIR(inode->i_mode)) 148 return ADFS_NDA_DIRECTORY; 149 150 attr = 0; 151 mode = ia_mode & asb->s_owner_mask; 152 if (mode & S_IRUGO) 153 attr |= ADFS_NDA_OWNER_READ; 154 if (mode & S_IWUGO) 155 attr |= ADFS_NDA_OWNER_WRITE; 156 157 mode = ia_mode & asb->s_other_mask; 158 mode &= ~asb->s_owner_mask; 159 if (mode & S_IRUGO) 160 attr |= ADFS_NDA_PUBLIC_READ; 161 if (mode & S_IWUGO) 162 attr |= ADFS_NDA_PUBLIC_WRITE; 163 164 return attr; 165 } 166 167 static const s64 nsec_unix_epoch_diff_risc_os_epoch = 2208988800000000000LL; 168 169 /* 170 * Convert an ADFS time to Unix time. ADFS has a 40-bit centi-second time 171 * referenced to 1 Jan 1900 (til 2248) so we need to discard 2208988800 seconds 172 * of time to convert from RISC OS epoch to Unix epoch. 173 */ 174 static void 175 adfs_adfs2unix_time(struct timespec64 *tv, struct inode *inode) 176 { 177 unsigned int high, low; 178 /* 01 Jan 1970 00:00:00 (Unix epoch) as nanoseconds since 179 * 01 Jan 1900 00:00:00 (RISC OS epoch) 180 */ 181 s64 nsec; 182 183 if (!adfs_inode_is_stamped(inode)) 184 goto cur_time; 185 186 high = ADFS_I(inode)->loadaddr & 0xFF; /* top 8 bits of timestamp */ 187 low = ADFS_I(inode)->execaddr; /* bottom 32 bits of timestamp */ 188 189 /* convert 40-bit centi-seconds to 32-bit seconds 190 * going via nanoseconds to retain precision 191 */ 192 nsec = (((s64) high << 32) | (s64) low) * 10000000; /* cs to ns */ 193 194 /* Files dated pre 01 Jan 1970 00:00:00. */ 195 if (nsec < nsec_unix_epoch_diff_risc_os_epoch) 196 goto too_early; 197 198 /* convert from RISC OS to Unix epoch */ 199 nsec -= nsec_unix_epoch_diff_risc_os_epoch; 200 201 *tv = ns_to_timespec64(nsec); 202 return; 203 204 cur_time: 205 *tv = current_time(inode); 206 return; 207 208 too_early: 209 tv->tv_sec = tv->tv_nsec = 0; 210 return; 211 } 212 213 /* Convert an Unix time to ADFS time for an entry that is already stamped. */ 214 static void adfs_unix2adfs_time(struct inode *inode, 215 const struct timespec64 *ts) 216 { 217 s64 cs, nsec = timespec64_to_ns(ts); 218 219 /* convert from Unix to RISC OS epoch */ 220 nsec += nsec_unix_epoch_diff_risc_os_epoch; 221 222 /* convert from nanoseconds to centiseconds */ 223 cs = div_s64(nsec, 10000000); 224 225 cs = clamp_t(s64, cs, 0, 0xffffffffff); 226 227 ADFS_I(inode)->loadaddr &= ~0xff; 228 ADFS_I(inode)->loadaddr |= (cs >> 32) & 0xff; 229 ADFS_I(inode)->execaddr = cs; 230 } 231 232 /* 233 * Fill in the inode information from the object information. 234 * 235 * Note that this is an inode-less filesystem, so we can't use the inode 236 * number to reference the metadata on the media. Instead, we use the 237 * inode number to hold the object ID, which in turn will tell us where 238 * the data is held. We also save the parent object ID, and with these 239 * two, we can locate the metadata. 240 * 241 * This does mean that we rely on an objects parent remaining the same at 242 * all times - we cannot cope with a cross-directory rename (yet). 243 */ 244 struct inode * 245 adfs_iget(struct super_block *sb, struct object_info *obj) 246 { 247 struct inode *inode; 248 struct timespec64 ts; 249 250 inode = new_inode(sb); 251 if (!inode) 252 goto out; 253 254 inode->i_uid = ADFS_SB(sb)->s_uid; 255 inode->i_gid = ADFS_SB(sb)->s_gid; 256 inode->i_ino = obj->indaddr; 257 inode->i_size = obj->size; 258 set_nlink(inode, 2); 259 inode->i_blocks = (inode->i_size + sb->s_blocksize - 1) >> 260 sb->s_blocksize_bits; 261 262 /* 263 * we need to save the parent directory ID so that 264 * write_inode can update the directory information 265 * for this file. This will need special handling 266 * for cross-directory renames. 267 */ 268 ADFS_I(inode)->parent_id = obj->parent_id; 269 ADFS_I(inode)->indaddr = obj->indaddr; 270 ADFS_I(inode)->loadaddr = obj->loadaddr; 271 ADFS_I(inode)->execaddr = obj->execaddr; 272 ADFS_I(inode)->attr = obj->attr; 273 274 inode->i_mode = adfs_atts2mode(sb, inode); 275 adfs_adfs2unix_time(&ts, inode); 276 inode_set_atime_to_ts(inode, ts); 277 inode_set_mtime_to_ts(inode, ts); 278 inode_set_ctime_to_ts(inode, ts); 279 280 if (S_ISDIR(inode->i_mode)) { 281 inode->i_op = &adfs_dir_inode_operations; 282 inode->i_fop = &adfs_dir_operations; 283 } else if (S_ISREG(inode->i_mode)) { 284 inode->i_op = &adfs_file_inode_operations; 285 inode->i_fop = &adfs_file_operations; 286 inode->i_mapping->a_ops = &adfs_aops; 287 ADFS_I(inode)->mmu_private = inode->i_size; 288 } 289 290 inode_fake_hash(inode); 291 292 out: 293 return inode; 294 } 295 296 /* 297 * Validate and convert a changed access mode/time to their ADFS equivalents. 298 * adfs_write_inode will actually write the information back to the directory 299 * later. 300 */ 301 int 302 adfs_notify_change(struct mnt_idmap *idmap, struct dentry *dentry, 303 struct iattr *attr) 304 { 305 struct inode *inode = d_inode(dentry); 306 struct super_block *sb = inode->i_sb; 307 unsigned int ia_valid = attr->ia_valid; 308 int error; 309 310 error = setattr_prepare(&nop_mnt_idmap, dentry, attr); 311 312 /* 313 * we can't change the UID or GID of any file - 314 * we have a global UID/GID in the superblock 315 */ 316 if ((ia_valid & ATTR_UID && !uid_eq(attr->ia_uid, ADFS_SB(sb)->s_uid)) || 317 (ia_valid & ATTR_GID && !gid_eq(attr->ia_gid, ADFS_SB(sb)->s_gid))) 318 error = -EPERM; 319 320 if (error) 321 goto out; 322 323 /* XXX: this is missing some actual on-disk truncation.. */ 324 if (ia_valid & ATTR_SIZE) 325 truncate_setsize(inode, attr->ia_size); 326 327 if (ia_valid & ATTR_MTIME && adfs_inode_is_stamped(inode)) { 328 adfs_unix2adfs_time(inode, &attr->ia_mtime); 329 adfs_adfs2unix_time(&attr->ia_mtime, inode); 330 inode_set_mtime_to_ts(inode, attr->ia_mtime); 331 } 332 333 /* 334 * FIXME: should we make these == to i_mtime since we don't 335 * have the ability to represent them in our filesystem? 336 */ 337 if (ia_valid & ATTR_ATIME) 338 inode_set_atime_to_ts(inode, attr->ia_atime); 339 if (ia_valid & ATTR_CTIME) 340 inode_set_ctime_to_ts(inode, attr->ia_ctime); 341 if (ia_valid & ATTR_MODE) { 342 ADFS_I(inode)->attr = adfs_mode2atts(sb, inode, attr->ia_mode); 343 inode->i_mode = adfs_atts2mode(sb, inode); 344 } 345 346 /* 347 * FIXME: should we be marking this inode dirty even if 348 * we don't have any metadata to write back? 349 */ 350 if (ia_valid & (ATTR_SIZE | ATTR_MTIME | ATTR_MODE)) 351 mark_inode_dirty(inode); 352 out: 353 return error; 354 } 355 356 /* 357 * write an existing inode back to the directory, and therefore the disk. 358 * The adfs-specific inode data has already been updated by 359 * adfs_notify_change() 360 */ 361 int adfs_write_inode(struct inode *inode, struct writeback_control *wbc) 362 { 363 struct super_block *sb = inode->i_sb; 364 struct object_info obj; 365 366 obj.indaddr = ADFS_I(inode)->indaddr; 367 obj.name_len = 0; 368 obj.parent_id = ADFS_I(inode)->parent_id; 369 obj.loadaddr = ADFS_I(inode)->loadaddr; 370 obj.execaddr = ADFS_I(inode)->execaddr; 371 obj.attr = ADFS_I(inode)->attr; 372 obj.size = inode->i_size; 373 374 return adfs_dir_update(sb, &obj, wbc->sync_mode == WB_SYNC_ALL); 375 } 376