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, inode->i_ino, block); 24 if (block) 25 map_bh(bh, inode->i_sb, block); 26 return 0; 27 } 28 /* don't support allocation of blocks yet */ 29 return -EIO; 30 31 abort_toobig: 32 return 0; 33 } 34 35 static int adfs_writepage(struct page *page, struct writeback_control *wbc) 36 { 37 return block_write_full_page(page, adfs_get_block, wbc); 38 } 39 40 static int adfs_readpage(struct file *file, struct page *page) 41 { 42 return block_read_full_page(page, adfs_get_block); 43 } 44 45 static void adfs_write_failed(struct address_space *mapping, loff_t to) 46 { 47 struct inode *inode = mapping->host; 48 49 if (to > inode->i_size) 50 truncate_pagecache(inode, inode->i_size); 51 } 52 53 static int adfs_write_begin(struct file *file, struct address_space *mapping, 54 loff_t pos, unsigned len, unsigned flags, 55 struct page **pagep, void **fsdata) 56 { 57 int ret; 58 59 *pagep = NULL; 60 ret = cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata, 61 adfs_get_block, 62 &ADFS_I(mapping->host)->mmu_private); 63 if (unlikely(ret)) 64 adfs_write_failed(mapping, pos + len); 65 66 return ret; 67 } 68 69 static sector_t _adfs_bmap(struct address_space *mapping, sector_t block) 70 { 71 return generic_block_bmap(mapping, block, adfs_get_block); 72 } 73 74 static const struct address_space_operations adfs_aops = { 75 .readpage = adfs_readpage, 76 .writepage = adfs_writepage, 77 .write_begin = adfs_write_begin, 78 .write_end = generic_write_end, 79 .bmap = _adfs_bmap 80 }; 81 82 /* 83 * Convert ADFS attributes and filetype to Linux permission. 84 */ 85 static umode_t 86 adfs_atts2mode(struct super_block *sb, struct inode *inode) 87 { 88 unsigned int attr = ADFS_I(inode)->attr; 89 umode_t mode, rmask; 90 struct adfs_sb_info *asb = ADFS_SB(sb); 91 92 if (attr & ADFS_NDA_DIRECTORY) { 93 mode = S_IRUGO & asb->s_owner_mask; 94 return S_IFDIR | S_IXUGO | mode; 95 } 96 97 switch (adfs_filetype(ADFS_I(inode)->loadaddr)) { 98 case 0xfc0: /* LinkFS */ 99 return S_IFLNK|S_IRWXUGO; 100 101 case 0xfe6: /* UnixExec */ 102 rmask = S_IRUGO | S_IXUGO; 103 break; 104 105 default: 106 rmask = S_IRUGO; 107 } 108 109 mode = S_IFREG; 110 111 if (attr & ADFS_NDA_OWNER_READ) 112 mode |= rmask & asb->s_owner_mask; 113 114 if (attr & ADFS_NDA_OWNER_WRITE) 115 mode |= S_IWUGO & asb->s_owner_mask; 116 117 if (attr & ADFS_NDA_PUBLIC_READ) 118 mode |= rmask & asb->s_other_mask; 119 120 if (attr & ADFS_NDA_PUBLIC_WRITE) 121 mode |= S_IWUGO & asb->s_other_mask; 122 return mode; 123 } 124 125 /* 126 * Convert Linux permission to ADFS attribute. We try to do the reverse 127 * of atts2mode, but there is not a 1:1 translation. 128 */ 129 static int 130 adfs_mode2atts(struct super_block *sb, struct inode *inode) 131 { 132 umode_t mode; 133 int attr; 134 struct adfs_sb_info *asb = ADFS_SB(sb); 135 136 /* FIXME: should we be able to alter a link? */ 137 if (S_ISLNK(inode->i_mode)) 138 return ADFS_I(inode)->attr; 139 140 if (S_ISDIR(inode->i_mode)) 141 attr = ADFS_NDA_DIRECTORY; 142 else 143 attr = 0; 144 145 mode = inode->i_mode & asb->s_owner_mask; 146 if (mode & S_IRUGO) 147 attr |= ADFS_NDA_OWNER_READ; 148 if (mode & S_IWUGO) 149 attr |= ADFS_NDA_OWNER_WRITE; 150 151 mode = inode->i_mode & asb->s_other_mask; 152 mode &= ~asb->s_owner_mask; 153 if (mode & S_IRUGO) 154 attr |= ADFS_NDA_PUBLIC_READ; 155 if (mode & S_IWUGO) 156 attr |= ADFS_NDA_PUBLIC_WRITE; 157 158 return attr; 159 } 160 161 /* 162 * Convert an ADFS time to Unix time. ADFS has a 40-bit centi-second time 163 * referenced to 1 Jan 1900 (til 2248) so we need to discard 2208988800 seconds 164 * of time to convert from RISC OS epoch to Unix epoch. 165 */ 166 static void 167 adfs_adfs2unix_time(struct timespec64 *tv, struct inode *inode) 168 { 169 unsigned int high, low; 170 /* 01 Jan 1970 00:00:00 (Unix epoch) as nanoseconds since 171 * 01 Jan 1900 00:00:00 (RISC OS epoch) 172 */ 173 static const s64 nsec_unix_epoch_diff_risc_os_epoch = 174 2208988800000000000LL; 175 s64 nsec; 176 177 if (!adfs_inode_is_stamped(inode)) 178 goto cur_time; 179 180 high = ADFS_I(inode)->loadaddr & 0xFF; /* top 8 bits of timestamp */ 181 low = ADFS_I(inode)->execaddr; /* bottom 32 bits of timestamp */ 182 183 /* convert 40-bit centi-seconds to 32-bit seconds 184 * going via nanoseconds to retain precision 185 */ 186 nsec = (((s64) high << 32) | (s64) low) * 10000000; /* cs to ns */ 187 188 /* Files dated pre 01 Jan 1970 00:00:00. */ 189 if (nsec < nsec_unix_epoch_diff_risc_os_epoch) 190 goto too_early; 191 192 /* convert from RISC OS to Unix epoch */ 193 nsec -= nsec_unix_epoch_diff_risc_os_epoch; 194 195 *tv = ns_to_timespec64(nsec); 196 return; 197 198 cur_time: 199 *tv = current_time(inode); 200 return; 201 202 too_early: 203 tv->tv_sec = tv->tv_nsec = 0; 204 return; 205 } 206 207 /* 208 * Convert an Unix time to ADFS time. We only do this if the entry has a 209 * time/date stamp already. 210 */ 211 static void 212 adfs_unix2adfs_time(struct inode *inode, unsigned int secs) 213 { 214 unsigned int high, low; 215 216 if (adfs_inode_is_stamped(inode)) { 217 /* convert 32-bit seconds to 40-bit centi-seconds */ 218 low = (secs & 255) * 100; 219 high = (secs / 256) * 100 + (low >> 8) + 0x336e996a; 220 221 ADFS_I(inode)->loadaddr = (high >> 24) | 222 (ADFS_I(inode)->loadaddr & ~0xff); 223 ADFS_I(inode)->execaddr = (low & 255) | (high << 8); 224 } 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)->loadaddr = obj->loadaddr; 264 ADFS_I(inode)->execaddr = obj->execaddr; 265 ADFS_I(inode)->attr = obj->attr; 266 267 inode->i_mode = adfs_atts2mode(sb, inode); 268 adfs_adfs2unix_time(&inode->i_mtime, inode); 269 inode->i_atime = inode->i_mtime; 270 inode->i_ctime = inode->i_mtime; 271 272 if (S_ISDIR(inode->i_mode)) { 273 inode->i_op = &adfs_dir_inode_operations; 274 inode->i_fop = &adfs_dir_operations; 275 } else if (S_ISREG(inode->i_mode)) { 276 inode->i_op = &adfs_file_inode_operations; 277 inode->i_fop = &adfs_file_operations; 278 inode->i_mapping->a_ops = &adfs_aops; 279 ADFS_I(inode)->mmu_private = inode->i_size; 280 } 281 282 inode_fake_hash(inode); 283 284 out: 285 return inode; 286 } 287 288 /* 289 * Validate and convert a changed access mode/time to their ADFS equivalents. 290 * adfs_write_inode will actually write the information back to the directory 291 * later. 292 */ 293 int 294 adfs_notify_change(struct dentry *dentry, struct iattr *attr) 295 { 296 struct inode *inode = d_inode(dentry); 297 struct super_block *sb = inode->i_sb; 298 unsigned int ia_valid = attr->ia_valid; 299 int error; 300 301 error = setattr_prepare(dentry, attr); 302 303 /* 304 * we can't change the UID or GID of any file - 305 * we have a global UID/GID in the superblock 306 */ 307 if ((ia_valid & ATTR_UID && !uid_eq(attr->ia_uid, ADFS_SB(sb)->s_uid)) || 308 (ia_valid & ATTR_GID && !gid_eq(attr->ia_gid, ADFS_SB(sb)->s_gid))) 309 error = -EPERM; 310 311 if (error) 312 goto out; 313 314 /* XXX: this is missing some actual on-disk truncation.. */ 315 if (ia_valid & ATTR_SIZE) 316 truncate_setsize(inode, attr->ia_size); 317 318 if (ia_valid & ATTR_MTIME) { 319 inode->i_mtime = attr->ia_mtime; 320 adfs_unix2adfs_time(inode, attr->ia_mtime.tv_sec); 321 } 322 /* 323 * FIXME: should we make these == to i_mtime since we don't 324 * have the ability to represent them in our filesystem? 325 */ 326 if (ia_valid & ATTR_ATIME) 327 inode->i_atime = attr->ia_atime; 328 if (ia_valid & ATTR_CTIME) 329 inode->i_ctime = attr->ia_ctime; 330 if (ia_valid & ATTR_MODE) { 331 ADFS_I(inode)->attr = adfs_mode2atts(sb, inode); 332 inode->i_mode = adfs_atts2mode(sb, inode); 333 } 334 335 /* 336 * FIXME: should we be marking this inode dirty even if 337 * we don't have any metadata to write back? 338 */ 339 if (ia_valid & (ATTR_SIZE | ATTR_MTIME | ATTR_MODE)) 340 mark_inode_dirty(inode); 341 out: 342 return error; 343 } 344 345 /* 346 * write an existing inode back to the directory, and therefore the disk. 347 * The adfs-specific inode data has already been updated by 348 * adfs_notify_change() 349 */ 350 int adfs_write_inode(struct inode *inode, struct writeback_control *wbc) 351 { 352 struct super_block *sb = inode->i_sb; 353 struct object_info obj; 354 int ret; 355 356 obj.indaddr = inode->i_ino; 357 obj.name_len = 0; 358 obj.parent_id = ADFS_I(inode)->parent_id; 359 obj.loadaddr = ADFS_I(inode)->loadaddr; 360 obj.execaddr = ADFS_I(inode)->execaddr; 361 obj.attr = ADFS_I(inode)->attr; 362 obj.size = inode->i_size; 363 364 ret = adfs_dir_update(sb, &obj, wbc->sync_mode == WB_SYNC_ALL); 365 return ret; 366 } 367