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