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