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/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         .readpage       = adfs_readpage,
  77         .writepage      = adfs_writepage,
  78         .write_begin    = adfs_write_begin,
  79         .write_end      = generic_write_end,
  80         .bmap           = _adfs_bmap
  81 };
  82
  83 /*
  84  * Convert ADFS attributes and filetype to Linux permission.
  85  */
  86 static umode_t
  87 adfs_atts2mode(struct super_block *sb, struct inode *inode)
  88 {
  89         unsigned int attr = ADFS_I(inode)->attr;
  90         umode_t mode, rmask;
  91         struct adfs_sb_info *asb = ADFS_SB(sb);
  92
  93         if (attr & ADFS_NDA_DIRECTORY) {
  94                 mode = S_IRUGO & asb->s_owner_mask;
  95                 return S_IFDIR | S_IXUGO | mode;
  96         }
  97
  98         switch (adfs_filetype(ADFS_I(inode)->loadaddr)) {
  99         case 0xfc0:     /* LinkFS */
 100                 return S_IFLNK|S_IRWXUGO;
 101
 102         case 0xfe6:     /* UnixExec */
 103                 rmask = S_IRUGO | S_IXUGO;
 104                 break;
 105
 106         default:
 107                 rmask = S_IRUGO;
 108         }
 109
 110         mode = S_IFREG;
 111
 112         if (attr & ADFS_NDA_OWNER_READ)
 113                 mode |= rmask & asb->s_owner_mask;
 114
 115         if (attr & ADFS_NDA_OWNER_WRITE)
 116                 mode |= S_IWUGO & asb->s_owner_mask;
 117
 118         if (attr & ADFS_NDA_PUBLIC_READ)
 119                 mode |= rmask & asb->s_other_mask;
 120
 121         if (attr & ADFS_NDA_PUBLIC_WRITE)
 122                 mode |= S_IWUGO & asb->s_other_mask;
 123         return mode;
 124 }
 125
 126 /*
 127  * Convert Linux permission to ADFS attribute.  We try to do the reverse
 128  * of atts2mode, but there is not a 1:1 translation.
 129  */
 130 static int adfs_mode2atts(struct super_block *sb, struct inode *inode,
 131                           umode_t ia_mode)
 132 {
 133         struct adfs_sb_info *asb = ADFS_SB(sb);
 134         umode_t mode;
 135         int attr;
 136
 137         /* FIXME: should we be able to alter a link? */
 138         if (S_ISLNK(inode->i_mode))
 139                 return ADFS_I(inode)->attr;
 140
 141         /* Directories do not have read/write permissions on the media */
 142         if (S_ISDIR(inode->i_mode))
 143                 return ADFS_NDA_DIRECTORY;
 144
 145         attr = 0;
 146         mode = ia_mode & asb->s_owner_mask;
 147         if (mode & S_IRUGO)
 148                 attr |= ADFS_NDA_OWNER_READ;
 149         if (mode & S_IWUGO)
 150                 attr |= ADFS_NDA_OWNER_WRITE;
 151
 152         mode = ia_mode & asb->s_other_mask;
 153         mode &= ~asb->s_owner_mask;
 154         if (mode & S_IRUGO)
 155                 attr |= ADFS_NDA_PUBLIC_READ;
 156         if (mode & S_IWUGO)
 157                 attr |= ADFS_NDA_PUBLIC_WRITE;
 158
 159         return attr;
 160 }
 161
 162 static const s64 nsec_unix_epoch_diff_risc_os_epoch = 2208988800000000000LL;
 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 timespec64 *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         s64 nsec;
 177
 178         if (!adfs_inode_is_stamped(inode))
 179                 goto cur_time;
 180
 181         high = ADFS_I(inode)->loadaddr & 0xFF; /* top 8 bits of timestamp */
 182         low  = ADFS_I(inode)->execaddr;    /* bottom 32 bits of timestamp */
 183
 184         /* convert 40-bit centi-seconds to 32-bit seconds
 185          * going via nanoseconds to retain precision
 186          */
 187         nsec = (((s64) high << 32) | (s64) low) * 10000000; /* cs to ns */
 188
 189         /* Files dated pre  01 Jan 1970 00:00:00. */
 190         if (nsec < nsec_unix_epoch_diff_risc_os_epoch)
 191                 goto too_early;
 192
 193         /* convert from RISC OS to Unix epoch */
 194         nsec -= nsec_unix_epoch_diff_risc_os_epoch;
 195
 196         *tv = ns_to_timespec64(nsec);
 197         return;
 198
 199  cur_time:
 200         *tv = current_time(inode);
 201         return;
 202
 203  too_early:
 204         tv->tv_sec = tv->tv_nsec = 0;
 205         return;
 206 }
 207
 208 /* Convert an Unix time to ADFS time for an entry that is already stamped. */
 209 static void adfs_unix2adfs_time(struct inode *inode,
 210                                 const struct timespec64 *ts)
 211 {
 212         s64 cs, nsec = timespec64_to_ns(ts);
 213
 214         /* convert from Unix to RISC OS epoch */
 215         nsec += nsec_unix_epoch_diff_risc_os_epoch;
 216
 217         /* convert from nanoseconds to centiseconds */
 218         cs = div_s64(nsec, 10000000);
 219
 220         cs = clamp_t(s64, cs, 0, 0xffffffffff);
 221
 222         ADFS_I(inode)->loadaddr &= ~0xff;
 223         ADFS_I(inode)->loadaddr |= (cs >> 32) & 0xff;
 224         ADFS_I(inode)->execaddr = cs;
 225 }
 226
 227 /*
 228  * Fill in the inode information from the object information.
 229  *
 230  * Note that this is an inode-less filesystem, so we can't use the inode
 231  * number to reference the metadata on the media.  Instead, we use the
 232  * inode number to hold the object ID, which in turn will tell us where
 233  * the data is held.  We also save the parent object ID, and with these
 234  * two, we can locate the metadata.
 235  *
 236  * This does mean that we rely on an objects parent remaining the same at
 237  * all times - we cannot cope with a cross-directory rename (yet).
 238  */
 239 struct inode *
 240 adfs_iget(struct super_block *sb, struct object_info *obj)
 241 {
 242         struct inode *inode;
 243
 244         inode = new_inode(sb);
 245         if (!inode)
 246                 goto out;
 247
 248         inode->i_uid     = ADFS_SB(sb)->s_uid;
 249         inode->i_gid     = ADFS_SB(sb)->s_gid;
 250         inode->i_ino     = obj->indaddr;
 251         inode->i_size    = obj->size;
 252         set_nlink(inode, 2);
 253         inode->i_blocks  = (inode->i_size + sb->s_blocksize - 1) >>
 254                             sb->s_blocksize_bits;
 255
 256         /*
 257          * we need to save the parent directory ID so that
 258          * write_inode can update the directory information
 259          * for this file.  This will need special handling
 260          * for cross-directory renames.
 261          */
 262         ADFS_I(inode)->parent_id = obj->parent_id;
 263         ADFS_I(inode)->indaddr   = obj->indaddr;
 264         ADFS_I(inode)->loadaddr  = obj->loadaddr;
 265         ADFS_I(inode)->execaddr  = obj->execaddr;
 266         ADFS_I(inode)->attr      = obj->attr;
 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         inode_fake_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 = d_inode(dentry);
 298         struct super_block *sb = inode->i_sb;
 299         unsigned int ia_valid = attr->ia_valid;
 300         int error;
 301
 302         error = setattr_prepare(dentry, 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 && !uid_eq(attr->ia_uid, ADFS_SB(sb)->s_uid)) ||
 309             (ia_valid & ATTR_GID && !gid_eq(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 && adfs_inode_is_stamped(inode)) {
 320                 adfs_unix2adfs_time(inode, &attr->ia_mtime);
 321                 adfs_adfs2unix_time(&inode->i_mtime, inode);
 322         }
 323
 324         /*
 325          * FIXME: should we make these == to i_mtime since we don't
 326          * have the ability to represent them in our filesystem?
 327          */
 328         if (ia_valid & ATTR_ATIME)
 329                 inode->i_atime = attr->ia_atime;
 330         if (ia_valid & ATTR_CTIME)
 331                 inode->i_ctime = attr->ia_ctime;
 332         if (ia_valid & ATTR_MODE) {
 333                 ADFS_I(inode)->attr = adfs_mode2atts(sb, inode, attr->ia_mode);
 334                 inode->i_mode = adfs_atts2mode(sb, inode);
 335         }
 336
 337         /*
 338          * FIXME: should we be marking this inode dirty even if
 339          * we don't have any metadata to write back?
 340          */
 341         if (ia_valid & (ATTR_SIZE | ATTR_MTIME | ATTR_MODE))
 342                 mark_inode_dirty(inode);
 343 out:
 344         return error;
 345 }
 346
 347 /*
 348  * write an existing inode back to the directory, and therefore the disk.
 349  * The adfs-specific inode data has already been updated by
 350  * adfs_notify_change()
 351  */
 352 int adfs_write_inode(struct inode *inode, struct writeback_control *wbc)
 353 {
 354         struct super_block *sb = inode->i_sb;
 355         struct object_info obj;
 356         int ret;
 357
 358         obj.indaddr     = ADFS_I(inode)->indaddr;
 359         obj.name_len    = 0;
 360         obj.parent_id   = ADFS_I(inode)->parent_id;
 361         obj.loadaddr    = ADFS_I(inode)->loadaddr;
 362         obj.execaddr    = ADFS_I(inode)->execaddr;
 363         obj.attr        = ADFS_I(inode)->attr;
 364         obj.size        = inode->i_size;
 365
 366         ret = adfs_dir_update(sb, &obj, wbc->sync_mode == WB_SYNC_ALL);
 367         return ret;
 368 }