fs/adfs/inode.c

   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/mpage.h>
   9 #include <linux/writeback.h>
  10 #include "adfs.h"
  11
  12 /*
  13  * Lookup/Create a block at offset 'block' into 'inode'.  We currently do
  14  * not support creation of new blocks, so we return -EIO for this case.
  15  */
  16 static int
  17 adfs_get_block(struct inode *inode, sector_t block, struct buffer_head *bh,
  18                int create)
  19 {
  20         if (!create) {
  21                 if (block >= inode->i_blocks)
  22                         goto abort_toobig;
  23
  24                 block = __adfs_block_map(inode->i_sb, ADFS_I(inode)->indaddr,
  25                                          block);
  26                 if (block)
  27                         map_bh(bh, inode->i_sb, block);
  28                 return 0;
  29         }
  30         /* don't support allocation of blocks yet */
  31         return -EIO;
  32
  33 abort_toobig:
  34         return 0;
  35 }
  36
  37 static int adfs_writepages(struct address_space *mapping,
  38                 struct writeback_control *wbc)
  39 {
  40         return mpage_writepages(mapping, wbc, adfs_get_block);
  41 }
  42
  43 static int adfs_read_folio(struct file *file, struct folio *folio)
  44 {
  45         return block_read_full_folio(folio, 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,
  58                         struct folio **foliop, void **fsdata)
  59 {
  60         int ret;
  61
  62         ret = cont_write_begin(file, mapping, pos, len, foliop, fsdata,
  63                                 adfs_get_block,
  64                                 &ADFS_I(mapping->host)->mmu_private);
  65         if (unlikely(ret))
  66                 adfs_write_failed(mapping, pos + len);
  67
  68         return ret;
  69 }
  70
  71 static sector_t _adfs_bmap(struct address_space *mapping, sector_t block)
  72 {
  73         return generic_block_bmap(mapping, block, adfs_get_block);
  74 }
  75
  76 static const struct address_space_operations adfs_aops = {
  77         .dirty_folio    = block_dirty_folio,
  78         .invalidate_folio = block_invalidate_folio,
  79         .read_folio     = adfs_read_folio,
  80         .writepages     = adfs_writepages,
  81         .write_begin    = adfs_write_begin,
  82         .write_end      = generic_write_end,
  83         .migrate_folio  = buffer_migrate_folio,
  84         .bmap           = _adfs_bmap,
  85 };
  86
  87 /*
  88  * Convert ADFS attributes and filetype to Linux permission.
  89  */
  90 static umode_t
  91 adfs_atts2mode(struct super_block *sb, struct inode *inode)
  92 {
  93         unsigned int attr = ADFS_I(inode)->attr;
  94         umode_t mode, rmask;
  95         struct adfs_sb_info *asb = ADFS_SB(sb);
  96
  97         if (attr & ADFS_NDA_DIRECTORY) {
  98                 mode = S_IRUGO & asb->s_owner_mask;
  99                 return S_IFDIR | S_IXUGO | mode;
 100         }
 101
 102         switch (adfs_filetype(ADFS_I(inode)->loadaddr)) {
 103         case 0xfc0:     /* LinkFS */
 104                 return S_IFLNK|S_IRWXUGO;
 105
 106         case 0xfe6:     /* UnixExec */
 107                 rmask = S_IRUGO | S_IXUGO;
 108                 break;
 109
 110         default:
 111                 rmask = S_IRUGO;
 112         }
 113
 114         mode = S_IFREG;
 115
 116         if (attr & ADFS_NDA_OWNER_READ)
 117                 mode |= rmask & asb->s_owner_mask;
 118
 119         if (attr & ADFS_NDA_OWNER_WRITE)
 120                 mode |= S_IWUGO & asb->s_owner_mask;
 121
 122         if (attr & ADFS_NDA_PUBLIC_READ)
 123                 mode |= rmask & asb->s_other_mask;
 124
 125         if (attr & ADFS_NDA_PUBLIC_WRITE)
 126                 mode |= S_IWUGO & asb->s_other_mask;
 127         return mode;
 128 }
 129
 130 /*
 131  * Convert Linux permission to ADFS attribute.  We try to do the reverse
 132  * of atts2mode, but there is not a 1:1 translation.
 133  */
 134 static int adfs_mode2atts(struct super_block *sb, struct inode *inode,
 135                           umode_t ia_mode)
 136 {
 137         struct adfs_sb_info *asb = ADFS_SB(sb);
 138         umode_t mode;
 139         int attr;
 140
 141         /* FIXME: should we be able to alter a link? */
 142         if (S_ISLNK(inode->i_mode))
 143                 return ADFS_I(inode)->attr;
 144
 145         /* Directories do not have read/write permissions on the media */
 146         if (S_ISDIR(inode->i_mode))
 147                 return ADFS_NDA_DIRECTORY;
 148
 149         attr = 0;
 150         mode = ia_mode & asb->s_owner_mask;
 151         if (mode & S_IRUGO)
 152                 attr |= ADFS_NDA_OWNER_READ;
 153         if (mode & S_IWUGO)
 154                 attr |= ADFS_NDA_OWNER_WRITE;
 155
 156         mode = ia_mode & asb->s_other_mask;
 157         mode &= ~asb->s_owner_mask;
 158         if (mode & S_IRUGO)
 159                 attr |= ADFS_NDA_PUBLIC_READ;
 160         if (mode & S_IWUGO)
 161                 attr |= ADFS_NDA_PUBLIC_WRITE;
 162
 163         return attr;
 164 }
 165
 166 static const s64 nsec_unix_epoch_diff_risc_os_epoch = 2208988800000000000LL;
 167
 168 /*
 169  * Convert an ADFS time to Unix time.  ADFS has a 40-bit centi-second time
 170  * referenced to 1 Jan 1900 (til 2248) so we need to discard 2208988800 seconds
 171  * of time to convert from RISC OS epoch to Unix epoch.
 172  */
 173 static void
 174 adfs_adfs2unix_time(struct timespec64 *tv, struct inode *inode)
 175 {
 176         unsigned int high, low;
 177         /* 01 Jan 1970 00:00:00 (Unix epoch) as nanoseconds since
 178          * 01 Jan 1900 00:00:00 (RISC OS epoch)
 179          */
 180         s64 nsec;
 181
 182         if (!adfs_inode_is_stamped(inode))
 183                 goto cur_time;
 184
 185         high = ADFS_I(inode)->loadaddr & 0xFF; /* top 8 bits of timestamp */
 186         low  = ADFS_I(inode)->execaddr;    /* bottom 32 bits of timestamp */
 187
 188         /* convert 40-bit centi-seconds to 32-bit seconds
 189          * going via nanoseconds to retain precision
 190          */
 191         nsec = (((s64) high << 32) | (s64) low) * 10000000; /* cs to ns */
 192
 193         /* Files dated pre  01 Jan 1970 00:00:00. */
 194         if (nsec < nsec_unix_epoch_diff_risc_os_epoch)
 195                 goto too_early;
 196
 197         /* convert from RISC OS to Unix epoch */
 198         nsec -= nsec_unix_epoch_diff_risc_os_epoch;
 199
 200         *tv = ns_to_timespec64(nsec);
 201         return;
 202
 203  cur_time:
 204         *tv = current_time(inode);
 205         return;
 206
 207  too_early:
 208         tv->tv_sec = tv->tv_nsec = 0;
 209         return;
 210 }
 211
 212 /* Convert an Unix time to ADFS time for an entry that is already stamped. */
 213 static void adfs_unix2adfs_time(struct inode *inode,
 214                                 const struct timespec64 *ts)
 215 {
 216         s64 cs, nsec = timespec64_to_ns(ts);
 217
 218         /* convert from Unix to RISC OS epoch */
 219         nsec += nsec_unix_epoch_diff_risc_os_epoch;
 220
 221         /* convert from nanoseconds to centiseconds */
 222         cs = div_s64(nsec, 10000000);
 223
 224         cs = clamp_t(s64, cs, 0, 0xffffffffff);
 225
 226         ADFS_I(inode)->loadaddr &= ~0xff;
 227         ADFS_I(inode)->loadaddr |= (cs >> 32) & 0xff;
 228         ADFS_I(inode)->execaddr = cs;
 229 }
 230
 231 /*
 232  * Fill in the inode information from the object information.
 233  *
 234  * Note that this is an inode-less filesystem, so we can't use the inode
 235  * number to reference the metadata on the media.  Instead, we use the
 236  * inode number to hold the object ID, which in turn will tell us where
 237  * the data is held.  We also save the parent object ID, and with these
 238  * two, we can locate the metadata.
 239  *
 240  * This does mean that we rely on an objects parent remaining the same at
 241  * all times - we cannot cope with a cross-directory rename (yet).
 242  */
 243 struct inode *
 244 adfs_iget(struct super_block *sb, struct object_info *obj)
 245 {
 246         struct inode *inode;
 247         struct timespec64 ts;
 248
 249         inode = new_inode(sb);
 250         if (!inode)
 251                 goto out;
 252
 253         inode->i_uid     = ADFS_SB(sb)->s_uid;
 254         inode->i_gid     = ADFS_SB(sb)->s_gid;
 255         inode->i_ino     = obj->indaddr;
 256         inode->i_size    = obj->size;
 257         set_nlink(inode, 2);
 258         inode->i_blocks  = (inode->i_size + sb->s_blocksize - 1) >>
 259                             sb->s_blocksize_bits;
 260
 261         /*
 262          * we need to save the parent directory ID so that
 263          * write_inode can update the directory information
 264          * for this file.  This will need special handling
 265          * for cross-directory renames.
 266          */
 267         ADFS_I(inode)->parent_id = obj->parent_id;
 268         ADFS_I(inode)->indaddr   = obj->indaddr;
 269         ADFS_I(inode)->loadaddr  = obj->loadaddr;
 270         ADFS_I(inode)->execaddr  = obj->execaddr;
 271         ADFS_I(inode)->attr      = obj->attr;
 272
 273         inode->i_mode    = adfs_atts2mode(sb, inode);
 274         adfs_adfs2unix_time(&ts, inode);
 275         inode_set_atime_to_ts(inode, ts);
 276         inode_set_mtime_to_ts(inode, ts);
 277         inode_set_ctime_to_ts(inode, ts);
 278
 279         if (S_ISDIR(inode->i_mode)) {
 280                 inode->i_op     = &adfs_dir_inode_operations;
 281                 inode->i_fop    = &adfs_dir_operations;
 282         } else if (S_ISREG(inode->i_mode)) {
 283                 inode->i_op     = &adfs_file_inode_operations;
 284                 inode->i_fop    = &adfs_file_operations;
 285                 inode->i_mapping->a_ops = &adfs_aops;
 286                 ADFS_I(inode)->mmu_private = inode->i_size;
 287         }
 288
 289         inode_fake_hash(inode);
 290
 291 out:
 292         return inode;
 293 }
 294
 295 /*
 296  * Validate and convert a changed access mode/time to their ADFS equivalents.
 297  * adfs_write_inode will actually write the information back to the directory
 298  * later.
 299  */
 300 int
 301 adfs_notify_change(struct mnt_idmap *idmap, struct dentry *dentry,
 302                    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(&nop_mnt_idmap, 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 && adfs_inode_is_stamped(inode)) {
 327                 adfs_unix2adfs_time(inode, &attr->ia_mtime);
 328                 adfs_adfs2unix_time(&attr->ia_mtime, inode);
 329                 inode_set_mtime_to_ts(inode, attr->ia_mtime);
 330         }
 331
 332         /*
 333          * FIXME: should we make these == to i_mtime since we don't
 334          * have the ability to represent them in our filesystem?
 335          */
 336         if (ia_valid & ATTR_ATIME)
 337                 inode_set_atime_to_ts(inode, attr->ia_atime);
 338         if (ia_valid & ATTR_CTIME)
 339                 inode_set_ctime_to_ts(inode, attr->ia_ctime);
 340         if (ia_valid & ATTR_MODE) {
 341                 ADFS_I(inode)->attr = adfs_mode2atts(sb, inode, attr->ia_mode);
 342                 inode->i_mode = adfs_atts2mode(sb, inode);
 343         }
 344
 345         /*
 346          * FIXME: should we be marking this inode dirty even if
 347          * we don't have any metadata to write back?
 348          */
 349         if (ia_valid & (ATTR_SIZE | ATTR_MTIME | ATTR_MODE))
 350                 mark_inode_dirty(inode);
 351 out:
 352         return error;
 353 }
 354
 355 /*
 356  * write an existing inode back to the directory, and therefore the disk.
 357  * The adfs-specific inode data has already been updated by
 358  * adfs_notify_change()
 359  */
 360 int adfs_write_inode(struct inode *inode, struct writeback_control *wbc)
 361 {
 362         struct super_block *sb = inode->i_sb;
 363         struct object_info obj;
 364
 365         obj.indaddr     = ADFS_I(inode)->indaddr;
 366         obj.name_len    = 0;
 367         obj.parent_id   = ADFS_I(inode)->parent_id;
 368         obj.loadaddr    = ADFS_I(inode)->loadaddr;
 369         obj.execaddr    = ADFS_I(inode)->execaddr;
 370         obj.attr        = ADFS_I(inode)->attr;
 371         obj.size        = inode->i_size;
 372
 373         return adfs_dir_update(sb, &obj, wbc->sync_mode == WB_SYNC_ALL);
 374 }