1 /* 2 * linux/fs/adfs/inode.c 3 * 4 * Copyright (C) 1997-1999 Russell King 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 */ 10 #include <linux/buffer_head.h> 11 #include <linux/writeback.h> 12 #include "adfs.h" 13 14 /* 15 * Lookup/Create a block at offset 'block' into 'inode'. We currently do 16 * not support creation of new blocks, so we return -EIO for this case. 17 */ 18 static int 19 adfs_get_block(struct inode *inode, sector_t block, struct buffer_head *bh, 20 int create) 21 { 22 if (!create) { 23 if (block >= inode->i_blocks) 24 goto abort_toobig; 25 26 block = __adfs_block_map(inode->i_sb, inode->i_ino, block); 27 if (block) 28 map_bh(bh, inode->i_sb, block); 29 return 0; 30 } 31 /* don't support allocation of blocks yet */ 32 return -EIO; 33 34 abort_toobig: 35 return 0; 36 } 37 38 static int adfs_writepage(struct page *page, struct writeback_control *wbc) 39 { 40 return block_write_full_page(page, adfs_get_block, wbc); 41 } 42 43 static int adfs_readpage(struct file *file, struct page *page) 44 { 45 return block_read_full_page(page, 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, unsigned flags, 58 struct page **pagep, void **fsdata) 59 { 60 int ret; 61 62 *pagep = NULL; 63 ret = cont_write_begin(file, mapping, pos, len, flags, 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 .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_I(inode)->filetype) { 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 133 adfs_mode2atts(struct super_block *sb, struct inode *inode) 134 { 135 umode_t mode; 136 int attr; 137 struct adfs_sb_info *asb = ADFS_SB(sb); 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 if (S_ISDIR(inode->i_mode)) 144 attr = ADFS_NDA_DIRECTORY; 145 else 146 attr = 0; 147 148 mode = inode->i_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 = inode->i_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 /* 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 timespec *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 static const s64 nsec_unix_epoch_diff_risc_os_epoch = 177 2208988800000000000LL; 178 s64 nsec; 179 180 if (ADFS_I(inode)->stamped == 0) 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_timespec(nsec); 199 return; 200 201 cur_time: 202 *tv = timespec64_to_timespec(current_time(inode)); 203 return; 204 205 too_early: 206 tv->tv_sec = tv->tv_nsec = 0; 207 return; 208 } 209 210 /* 211 * Convert an Unix time to ADFS time. We only do this if the entry has a 212 * time/date stamp already. 213 */ 214 static void 215 adfs_unix2adfs_time(struct inode *inode, unsigned int secs) 216 { 217 unsigned int high, low; 218 219 if (ADFS_I(inode)->stamped) { 220 /* convert 32-bit seconds to 40-bit centi-seconds */ 221 low = (secs & 255) * 100; 222 high = (secs / 256) * 100 + (low >> 8) + 0x336e996a; 223 224 ADFS_I(inode)->loadaddr = (high >> 24) | 225 (ADFS_I(inode)->loadaddr & ~0xff); 226 ADFS_I(inode)->execaddr = (low & 255) | (high << 8); 227 } 228 } 229 230 /* 231 * Fill in the inode information from the object information. 232 * 233 * Note that this is an inode-less filesystem, so we can't use the inode 234 * number to reference the metadata on the media. Instead, we use the 235 * inode number to hold the object ID, which in turn will tell us where 236 * the data is held. We also save the parent object ID, and with these 237 * two, we can locate the metadata. 238 * 239 * This does mean that we rely on an objects parent remaining the same at 240 * all times - we cannot cope with a cross-directory rename (yet). 241 */ 242 struct inode * 243 adfs_iget(struct super_block *sb, struct object_info *obj) 244 { 245 struct timespec ts; 246 struct inode *inode; 247 248 inode = new_inode(sb); 249 if (!inode) 250 goto out; 251 252 inode->i_uid = ADFS_SB(sb)->s_uid; 253 inode->i_gid = ADFS_SB(sb)->s_gid; 254 inode->i_ino = obj->file_id; 255 inode->i_size = obj->size; 256 set_nlink(inode, 2); 257 inode->i_blocks = (inode->i_size + sb->s_blocksize - 1) >> 258 sb->s_blocksize_bits; 259 260 /* 261 * we need to save the parent directory ID so that 262 * write_inode can update the directory information 263 * for this file. This will need special handling 264 * for cross-directory renames. 265 */ 266 ADFS_I(inode)->parent_id = obj->parent_id; 267 ADFS_I(inode)->loadaddr = obj->loadaddr; 268 ADFS_I(inode)->execaddr = obj->execaddr; 269 ADFS_I(inode)->attr = obj->attr; 270 ADFS_I(inode)->filetype = obj->filetype; 271 ADFS_I(inode)->stamped = ((obj->loadaddr & 0xfff00000) == 0xfff00000); 272 273 inode->i_mode = adfs_atts2mode(sb, inode); 274 ts = timespec64_to_timespec(inode->i_mtime); 275 adfs_adfs2unix_time(&ts, inode); 276 inode->i_mtime = timespec_to_timespec64(ts); 277 inode->i_atime = inode->i_mtime; 278 inode->i_ctime = inode->i_mtime; 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 insert_inode_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 dentry *dentry, struct iattr *attr) 303 { 304 struct inode *inode = d_inode(dentry); 305 struct super_block *sb = inode->i_sb; 306 unsigned int ia_valid = attr->ia_valid; 307 int error; 308 309 error = setattr_prepare(dentry, attr); 310 311 /* 312 * we can't change the UID or GID of any file - 313 * we have a global UID/GID in the superblock 314 */ 315 if ((ia_valid & ATTR_UID && !uid_eq(attr->ia_uid, ADFS_SB(sb)->s_uid)) || 316 (ia_valid & ATTR_GID && !gid_eq(attr->ia_gid, ADFS_SB(sb)->s_gid))) 317 error = -EPERM; 318 319 if (error) 320 goto out; 321 322 /* XXX: this is missing some actual on-disk truncation.. */ 323 if (ia_valid & ATTR_SIZE) 324 truncate_setsize(inode, attr->ia_size); 325 326 if (ia_valid & ATTR_MTIME) { 327 inode->i_mtime = attr->ia_mtime; 328 adfs_unix2adfs_time(inode, attr->ia_mtime.tv_sec); 329 } 330 /* 331 * FIXME: should we make these == to i_mtime since we don't 332 * have the ability to represent them in our filesystem? 333 */ 334 if (ia_valid & ATTR_ATIME) 335 inode->i_atime = attr->ia_atime; 336 if (ia_valid & ATTR_CTIME) 337 inode->i_ctime = attr->ia_ctime; 338 if (ia_valid & ATTR_MODE) { 339 ADFS_I(inode)->attr = adfs_mode2atts(sb, inode); 340 inode->i_mode = adfs_atts2mode(sb, inode); 341 } 342 343 /* 344 * FIXME: should we be marking this inode dirty even if 345 * we don't have any metadata to write back? 346 */ 347 if (ia_valid & (ATTR_SIZE | ATTR_MTIME | ATTR_MODE)) 348 mark_inode_dirty(inode); 349 out: 350 return error; 351 } 352 353 /* 354 * write an existing inode back to the directory, and therefore the disk. 355 * The adfs-specific inode data has already been updated by 356 * adfs_notify_change() 357 */ 358 int adfs_write_inode(struct inode *inode, struct writeback_control *wbc) 359 { 360 struct super_block *sb = inode->i_sb; 361 struct object_info obj; 362 int ret; 363 364 obj.file_id = inode->i_ino; 365 obj.name_len = 0; 366 obj.parent_id = ADFS_I(inode)->parent_id; 367 obj.loadaddr = ADFS_I(inode)->loadaddr; 368 obj.execaddr = ADFS_I(inode)->execaddr; 369 obj.attr = ADFS_I(inode)->attr; 370 obj.size = inode->i_size; 371 372 ret = adfs_dir_update(sb, &obj, wbc->sync_mode == WB_SYNC_ALL); 373 return ret; 374 } 375