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 int adfs_write_begin(struct file *file, struct address_space *mapping, 49 loff_t pos, unsigned len, unsigned flags, 50 struct page **pagep, void **fsdata) 51 { 52 int ret; 53 54 *pagep = NULL; 55 ret = cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata, 56 adfs_get_block, 57 &ADFS_I(mapping->host)->mmu_private); 58 if (unlikely(ret)) { 59 loff_t isize = mapping->host->i_size; 60 if (pos + len > isize) 61 vmtruncate(mapping->host, isize); 62 } 63 64 return ret; 65 } 66 67 static sector_t _adfs_bmap(struct address_space *mapping, sector_t block) 68 { 69 return generic_block_bmap(mapping, block, adfs_get_block); 70 } 71 72 static const struct address_space_operations adfs_aops = { 73 .readpage = adfs_readpage, 74 .writepage = adfs_writepage, 75 .sync_page = block_sync_page, 76 .write_begin = adfs_write_begin, 77 .write_end = generic_write_end, 78 .bmap = _adfs_bmap 79 }; 80 81 /* 82 * Convert ADFS attributes and filetype to Linux permission. 83 */ 84 static umode_t 85 adfs_atts2mode(struct super_block *sb, struct inode *inode) 86 { 87 unsigned int attr = ADFS_I(inode)->attr; 88 umode_t mode, rmask; 89 struct adfs_sb_info *asb = ADFS_SB(sb); 90 91 if (attr & ADFS_NDA_DIRECTORY) { 92 mode = S_IRUGO & asb->s_owner_mask; 93 return S_IFDIR | S_IXUGO | mode; 94 } 95 96 switch (ADFS_I(inode)->filetype) { 97 case 0xfc0: /* LinkFS */ 98 return S_IFLNK|S_IRWXUGO; 99 100 case 0xfe6: /* UnixExec */ 101 rmask = S_IRUGO | S_IXUGO; 102 break; 103 104 default: 105 rmask = S_IRUGO; 106 } 107 108 mode = S_IFREG; 109 110 if (attr & ADFS_NDA_OWNER_READ) 111 mode |= rmask & asb->s_owner_mask; 112 113 if (attr & ADFS_NDA_OWNER_WRITE) 114 mode |= S_IWUGO & asb->s_owner_mask; 115 116 if (attr & ADFS_NDA_PUBLIC_READ) 117 mode |= rmask & asb->s_other_mask; 118 119 if (attr & ADFS_NDA_PUBLIC_WRITE) 120 mode |= S_IWUGO & asb->s_other_mask; 121 return mode; 122 } 123 124 /* 125 * Convert Linux permission to ADFS attribute. We try to do the reverse 126 * of atts2mode, but there is not a 1:1 translation. 127 */ 128 static int 129 adfs_mode2atts(struct super_block *sb, struct inode *inode) 130 { 131 umode_t mode; 132 int attr; 133 struct adfs_sb_info *asb = ADFS_SB(sb); 134 135 /* FIXME: should we be able to alter a link? */ 136 if (S_ISLNK(inode->i_mode)) 137 return ADFS_I(inode)->attr; 138 139 if (S_ISDIR(inode->i_mode)) 140 attr = ADFS_NDA_DIRECTORY; 141 else 142 attr = 0; 143 144 mode = inode->i_mode & asb->s_owner_mask; 145 if (mode & S_IRUGO) 146 attr |= ADFS_NDA_OWNER_READ; 147 if (mode & S_IWUGO) 148 attr |= ADFS_NDA_OWNER_WRITE; 149 150 mode = inode->i_mode & asb->s_other_mask; 151 mode &= ~asb->s_owner_mask; 152 if (mode & S_IRUGO) 153 attr |= ADFS_NDA_PUBLIC_READ; 154 if (mode & S_IWUGO) 155 attr |= ADFS_NDA_PUBLIC_WRITE; 156 157 return attr; 158 } 159 160 /* 161 * Convert an ADFS time to Unix time. ADFS has a 40-bit centi-second time 162 * referenced to 1 Jan 1900 (til 2248) so we need to discard 2208988800 seconds 163 * of time to convert from RISC OS epoch to Unix epoch. 164 */ 165 static void 166 adfs_adfs2unix_time(struct timespec *tv, struct inode *inode) 167 { 168 unsigned int high, low; 169 /* 01 Jan 1970 00:00:00 (Unix epoch) as nanoseconds since 170 * 01 Jan 1900 00:00:00 (RISC OS epoch) 171 */ 172 static const s64 nsec_unix_epoch_diff_risc_os_epoch = 173 2208988800000000000LL; 174 s64 nsec; 175 176 if (ADFS_I(inode)->stamped == 0) 177 goto cur_time; 178 179 high = ADFS_I(inode)->loadaddr & 0xFF; /* top 8 bits of timestamp */ 180 low = ADFS_I(inode)->execaddr; /* bottom 32 bits of timestamp */ 181 182 /* convert 40-bit centi-seconds to 32-bit seconds 183 * going via nanoseconds to retain precision 184 */ 185 nsec = (((s64) high << 32) | (s64) low) * 10000000; /* cs to ns */ 186 187 /* Files dated pre 01 Jan 1970 00:00:00. */ 188 if (nsec < nsec_unix_epoch_diff_risc_os_epoch) 189 goto too_early; 190 191 /* convert from RISC OS to Unix epoch */ 192 nsec -= nsec_unix_epoch_diff_risc_os_epoch; 193 194 *tv = ns_to_timespec(nsec); 195 return; 196 197 cur_time: 198 *tv = CURRENT_TIME; 199 return; 200 201 too_early: 202 tv->tv_sec = tv->tv_nsec = 0; 203 return; 204 } 205 206 /* 207 * Convert an Unix time to ADFS time. We only do this if the entry has a 208 * time/date stamp already. 209 */ 210 static void 211 adfs_unix2adfs_time(struct inode *inode, unsigned int secs) 212 { 213 unsigned int high, low; 214 215 if (ADFS_I(inode)->stamped) { 216 /* convert 32-bit seconds to 40-bit centi-seconds */ 217 low = (secs & 255) * 100; 218 high = (secs / 256) * 100 + (low >> 8) + 0x336e996a; 219 220 ADFS_I(inode)->loadaddr = (high >> 24) | 221 (ADFS_I(inode)->loadaddr & ~0xff); 222 ADFS_I(inode)->execaddr = (low & 255) | (high << 8); 223 } 224 } 225 226 /* 227 * Fill in the inode information from the object information. 228 * 229 * Note that this is an inode-less filesystem, so we can't use the inode 230 * number to reference the metadata on the media. Instead, we use the 231 * inode number to hold the object ID, which in turn will tell us where 232 * the data is held. We also save the parent object ID, and with these 233 * two, we can locate the metadata. 234 * 235 * This does mean that we rely on an objects parent remaining the same at 236 * all times - we cannot cope with a cross-directory rename (yet). 237 */ 238 struct inode * 239 adfs_iget(struct super_block *sb, struct object_info *obj) 240 { 241 struct inode *inode; 242 243 inode = new_inode(sb); 244 if (!inode) 245 goto out; 246 247 inode->i_uid = ADFS_SB(sb)->s_uid; 248 inode->i_gid = ADFS_SB(sb)->s_gid; 249 inode->i_ino = obj->file_id; 250 inode->i_size = obj->size; 251 inode->i_nlink = 2; 252 inode->i_blocks = (inode->i_size + sb->s_blocksize - 1) >> 253 sb->s_blocksize_bits; 254 255 /* 256 * we need to save the parent directory ID so that 257 * write_inode can update the directory information 258 * for this file. This will need special handling 259 * for cross-directory renames. 260 */ 261 ADFS_I(inode)->parent_id = obj->parent_id; 262 ADFS_I(inode)->loadaddr = obj->loadaddr; 263 ADFS_I(inode)->execaddr = obj->execaddr; 264 ADFS_I(inode)->attr = obj->attr; 265 ADFS_I(inode)->filetype = obj->filetype; 266 ADFS_I(inode)->stamped = ((obj->loadaddr & 0xfff00000) == 0xfff00000); 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 insert_inode_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 dentry *dentry, struct iattr *attr) 296 { 297 struct inode *inode = dentry->d_inode; 298 struct super_block *sb = inode->i_sb; 299 unsigned int ia_valid = attr->ia_valid; 300 int error; 301 302 error = inode_change_ok(inode, attr); 303 304 /* 305 * we can't change the UID or GID of any file - 306 * we have a global UID/GID in the superblock 307 */ 308 if ((ia_valid & ATTR_UID && attr->ia_uid != ADFS_SB(sb)->s_uid) || 309 (ia_valid & ATTR_GID && attr->ia_gid != ADFS_SB(sb)->s_gid)) 310 error = -EPERM; 311 312 if (error) 313 goto out; 314 315 /* XXX: this is missing some actual on-disk truncation.. */ 316 if (ia_valid & ATTR_SIZE) 317 truncate_setsize(inode, attr->ia_size); 318 319 if (ia_valid & ATTR_MTIME) { 320 inode->i_mtime = attr->ia_mtime; 321 adfs_unix2adfs_time(inode, attr->ia_mtime.tv_sec); 322 } 323 /* 324 * FIXME: should we make these == to i_mtime since we don't 325 * have the ability to represent them in our filesystem? 326 */ 327 if (ia_valid & ATTR_ATIME) 328 inode->i_atime = attr->ia_atime; 329 if (ia_valid & ATTR_CTIME) 330 inode->i_ctime = attr->ia_ctime; 331 if (ia_valid & ATTR_MODE) { 332 ADFS_I(inode)->attr = adfs_mode2atts(sb, inode); 333 inode->i_mode = adfs_atts2mode(sb, inode); 334 } 335 336 /* 337 * FIXME: should we be marking this inode dirty even if 338 * we don't have any metadata to write back? 339 */ 340 if (ia_valid & (ATTR_SIZE | ATTR_MTIME | ATTR_MODE)) 341 mark_inode_dirty(inode); 342 out: 343 return error; 344 } 345 346 /* 347 * write an existing inode back to the directory, and therefore the disk. 348 * The adfs-specific inode data has already been updated by 349 * adfs_notify_change() 350 */ 351 int adfs_write_inode(struct inode *inode, struct writeback_control *wbc) 352 { 353 struct super_block *sb = inode->i_sb; 354 struct object_info obj; 355 int ret; 356 357 obj.file_id = inode->i_ino; 358 obj.name_len = 0; 359 obj.parent_id = ADFS_I(inode)->parent_id; 360 obj.loadaddr = ADFS_I(inode)->loadaddr; 361 obj.execaddr = ADFS_I(inode)->execaddr; 362 obj.attr = ADFS_I(inode)->attr; 363 obj.size = inode->i_size; 364 365 ret = adfs_dir_update(sb, &obj, wbc->sync_mode == WB_SYNC_ALL); 366 return ret; 367 } 368