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 .write_begin = adfs_write_begin, 76 .write_end = generic_write_end, 77 .bmap = _adfs_bmap 78 }; 79 80 /* 81 * Convert ADFS attributes and filetype to Linux permission. 82 */ 83 static umode_t 84 adfs_atts2mode(struct super_block *sb, struct inode *inode) 85 { 86 unsigned int attr = ADFS_I(inode)->attr; 87 umode_t mode, rmask; 88 struct adfs_sb_info *asb = ADFS_SB(sb); 89 90 if (attr & ADFS_NDA_DIRECTORY) { 91 mode = S_IRUGO & asb->s_owner_mask; 92 return S_IFDIR | S_IXUGO | mode; 93 } 94 95 switch (ADFS_I(inode)->filetype) { 96 case 0xfc0: /* LinkFS */ 97 return S_IFLNK|S_IRWXUGO; 98 99 case 0xfe6: /* UnixExec */ 100 rmask = S_IRUGO | S_IXUGO; 101 break; 102 103 default: 104 rmask = S_IRUGO; 105 } 106 107 mode = S_IFREG; 108 109 if (attr & ADFS_NDA_OWNER_READ) 110 mode |= rmask & asb->s_owner_mask; 111 112 if (attr & ADFS_NDA_OWNER_WRITE) 113 mode |= S_IWUGO & asb->s_owner_mask; 114 115 if (attr & ADFS_NDA_PUBLIC_READ) 116 mode |= rmask & asb->s_other_mask; 117 118 if (attr & ADFS_NDA_PUBLIC_WRITE) 119 mode |= S_IWUGO & asb->s_other_mask; 120 return mode; 121 } 122 123 /* 124 * Convert Linux permission to ADFS attribute. We try to do the reverse 125 * of atts2mode, but there is not a 1:1 translation. 126 */ 127 static int 128 adfs_mode2atts(struct super_block *sb, struct inode *inode) 129 { 130 umode_t mode; 131 int attr; 132 struct adfs_sb_info *asb = ADFS_SB(sb); 133 134 /* FIXME: should we be able to alter a link? */ 135 if (S_ISLNK(inode->i_mode)) 136 return ADFS_I(inode)->attr; 137 138 if (S_ISDIR(inode->i_mode)) 139 attr = ADFS_NDA_DIRECTORY; 140 else 141 attr = 0; 142 143 mode = inode->i_mode & asb->s_owner_mask; 144 if (mode & S_IRUGO) 145 attr |= ADFS_NDA_OWNER_READ; 146 if (mode & S_IWUGO) 147 attr |= ADFS_NDA_OWNER_WRITE; 148 149 mode = inode->i_mode & asb->s_other_mask; 150 mode &= ~asb->s_owner_mask; 151 if (mode & S_IRUGO) 152 attr |= ADFS_NDA_PUBLIC_READ; 153 if (mode & S_IWUGO) 154 attr |= ADFS_NDA_PUBLIC_WRITE; 155 156 return attr; 157 } 158 159 /* 160 * Convert an ADFS time to Unix time. ADFS has a 40-bit centi-second time 161 * referenced to 1 Jan 1900 (til 2248) so we need to discard 2208988800 seconds 162 * of time to convert from RISC OS epoch to Unix epoch. 163 */ 164 static void 165 adfs_adfs2unix_time(struct timespec *tv, struct inode *inode) 166 { 167 unsigned int high, low; 168 /* 01 Jan 1970 00:00:00 (Unix epoch) as nanoseconds since 169 * 01 Jan 1900 00:00:00 (RISC OS epoch) 170 */ 171 static const s64 nsec_unix_epoch_diff_risc_os_epoch = 172 2208988800000000000LL; 173 s64 nsec; 174 175 if (ADFS_I(inode)->stamped == 0) 176 goto cur_time; 177 178 high = ADFS_I(inode)->loadaddr & 0xFF; /* top 8 bits of timestamp */ 179 low = ADFS_I(inode)->execaddr; /* bottom 32 bits of timestamp */ 180 181 /* convert 40-bit centi-seconds to 32-bit seconds 182 * going via nanoseconds to retain precision 183 */ 184 nsec = (((s64) high << 32) | (s64) low) * 10000000; /* cs to ns */ 185 186 /* Files dated pre 01 Jan 1970 00:00:00. */ 187 if (nsec < nsec_unix_epoch_diff_risc_os_epoch) 188 goto too_early; 189 190 /* convert from RISC OS to Unix epoch */ 191 nsec -= nsec_unix_epoch_diff_risc_os_epoch; 192 193 *tv = ns_to_timespec(nsec); 194 return; 195 196 cur_time: 197 *tv = CURRENT_TIME; 198 return; 199 200 too_early: 201 tv->tv_sec = tv->tv_nsec = 0; 202 return; 203 } 204 205 /* 206 * Convert an Unix time to ADFS time. We only do this if the entry has a 207 * time/date stamp already. 208 */ 209 static void 210 adfs_unix2adfs_time(struct inode *inode, unsigned int secs) 211 { 212 unsigned int high, low; 213 214 if (ADFS_I(inode)->stamped) { 215 /* convert 32-bit seconds to 40-bit centi-seconds */ 216 low = (secs & 255) * 100; 217 high = (secs / 256) * 100 + (low >> 8) + 0x336e996a; 218 219 ADFS_I(inode)->loadaddr = (high >> 24) | 220 (ADFS_I(inode)->loadaddr & ~0xff); 221 ADFS_I(inode)->execaddr = (low & 255) | (high << 8); 222 } 223 } 224 225 /* 226 * Fill in the inode information from the object information. 227 * 228 * Note that this is an inode-less filesystem, so we can't use the inode 229 * number to reference the metadata on the media. Instead, we use the 230 * inode number to hold the object ID, which in turn will tell us where 231 * the data is held. We also save the parent object ID, and with these 232 * two, we can locate the metadata. 233 * 234 * This does mean that we rely on an objects parent remaining the same at 235 * all times - we cannot cope with a cross-directory rename (yet). 236 */ 237 struct inode * 238 adfs_iget(struct super_block *sb, struct object_info *obj) 239 { 240 struct inode *inode; 241 242 inode = new_inode(sb); 243 if (!inode) 244 goto out; 245 246 inode->i_uid = ADFS_SB(sb)->s_uid; 247 inode->i_gid = ADFS_SB(sb)->s_gid; 248 inode->i_ino = obj->file_id; 249 inode->i_size = obj->size; 250 set_nlink(inode, 2); 251 inode->i_blocks = (inode->i_size + sb->s_blocksize - 1) >> 252 sb->s_blocksize_bits; 253 254 /* 255 * we need to save the parent directory ID so that 256 * write_inode can update the directory information 257 * for this file. This will need special handling 258 * for cross-directory renames. 259 */ 260 ADFS_I(inode)->parent_id = obj->parent_id; 261 ADFS_I(inode)->loadaddr = obj->loadaddr; 262 ADFS_I(inode)->execaddr = obj->execaddr; 263 ADFS_I(inode)->attr = obj->attr; 264 ADFS_I(inode)->filetype = obj->filetype; 265 ADFS_I(inode)->stamped = ((obj->loadaddr & 0xfff00000) == 0xfff00000); 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 insert_inode_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 = dentry->d_inode; 297 struct super_block *sb = inode->i_sb; 298 unsigned int ia_valid = attr->ia_valid; 299 int error; 300 301 error = inode_change_ok(inode, 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.file_id = 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