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, flags, 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 } 370