fs/adfs/inode.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  *  linux/fs/adfs/inode.c
0004  *
0005  *  Copyright (C) 1997-1999 Russell King
0006  */
0007 #include <linux/buffer_head.h>
0008 #include <linux/writeback.h>
0009 #include "adfs.h"
0010
0011 /*
0012  * Lookup/Create a block at offset 'block' into 'inode'.  We currently do
0013  * not support creation of new blocks, so we return -EIO for this case.
0014  */
0015 static int
0016 adfs_get_block(struct inode *inode, sector_t block, struct buffer_head *bh,
0017            int create)
0018 {
0019     if (!create) {
0020         if (block >= inode->i_blocks)
0021             goto abort_toobig;
0022
0023         block = __adfs_block_map(inode->i_sb, ADFS_I(inode)->indaddr,
0024                      block);
0025         if (block)
0026             map_bh(bh, inode->i_sb, block);
0027         return 0;
0028     }
0029     /* don't support allocation of blocks yet */
0030     return -EIO;
0031
0032 abort_toobig:
0033     return 0;
0034 }
0035
0036 static int adfs_writepage(struct page *page, struct writeback_control *wbc)
0037 {
0038     return block_write_full_page(page, adfs_get_block, wbc);
0039 }
0040
0041 static int adfs_read_folio(struct file *file, struct folio *folio)
0042 {
0043     return block_read_full_folio(folio, adfs_get_block);
0044 }
0045
0046 static void adfs_write_failed(struct address_space *mapping, loff_t to)
0047 {
0048     struct inode *inode = mapping->host;
0049
0050     if (to > inode->i_size)
0051         truncate_pagecache(inode, inode->i_size);
0052 }
0053
0054 static int adfs_write_begin(struct file *file, struct address_space *mapping,
0055             loff_t pos, unsigned len,
0056             struct page **pagep, void **fsdata)
0057 {
0058     int ret;
0059
0060     *pagep = NULL;
0061     ret = cont_write_begin(file, mapping, pos, len, pagep, fsdata,
0062                 adfs_get_block,
0063                 &ADFS_I(mapping->host)->mmu_private);
0064     if (unlikely(ret))
0065         adfs_write_failed(mapping, pos + len);
0066
0067     return ret;
0068 }
0069
0070 static sector_t _adfs_bmap(struct address_space *mapping, sector_t block)
0071 {
0072     return generic_block_bmap(mapping, block, adfs_get_block);
0073 }
0074
0075 static const struct address_space_operations adfs_aops = {
0076     .dirty_folio    = block_dirty_folio,
0077     .invalidate_folio = block_invalidate_folio,
0078     .read_folio = adfs_read_folio,
0079     .writepage  = adfs_writepage,
0080     .write_begin    = adfs_write_begin,
0081     .write_end  = generic_write_end,
0082     .bmap       = _adfs_bmap
0083 };
0084
0085 /*
0086  * Convert ADFS attributes and filetype to Linux permission.
0087  */
0088 static umode_t
0089 adfs_atts2mode(struct super_block *sb, struct inode *inode)
0090 {
0091     unsigned int attr = ADFS_I(inode)->attr;
0092     umode_t mode, rmask;
0093     struct adfs_sb_info *asb = ADFS_SB(sb);
0094
0095     if (attr & ADFS_NDA_DIRECTORY) {
0096         mode = S_IRUGO & asb->s_owner_mask;
0097         return S_IFDIR | S_IXUGO | mode;
0098     }
0099
0100     switch (adfs_filetype(ADFS_I(inode)->loadaddr)) {
0101     case 0xfc0: /* LinkFS */
0102         return S_IFLNK|S_IRWXUGO;
0103
0104     case 0xfe6: /* UnixExec */
0105         rmask = S_IRUGO | S_IXUGO;
0106         break;
0107
0108     default:
0109         rmask = S_IRUGO;
0110     }
0111
0112     mode = S_IFREG;
0113
0114     if (attr & ADFS_NDA_OWNER_READ)
0115         mode |= rmask & asb->s_owner_mask;
0116
0117     if (attr & ADFS_NDA_OWNER_WRITE)
0118         mode |= S_IWUGO & asb->s_owner_mask;
0119
0120     if (attr & ADFS_NDA_PUBLIC_READ)
0121         mode |= rmask & asb->s_other_mask;
0122
0123     if (attr & ADFS_NDA_PUBLIC_WRITE)
0124         mode |= S_IWUGO & asb->s_other_mask;
0125     return mode;
0126 }
0127
0128 /*
0129  * Convert Linux permission to ADFS attribute.  We try to do the reverse
0130  * of atts2mode, but there is not a 1:1 translation.
0131  */
0132 static int adfs_mode2atts(struct super_block *sb, struct inode *inode,
0133               umode_t ia_mode)
0134 {
0135     struct adfs_sb_info *asb = ADFS_SB(sb);
0136     umode_t mode;
0137     int attr;
0138
0139     /* FIXME: should we be able to alter a link? */
0140     if (S_ISLNK(inode->i_mode))
0141         return ADFS_I(inode)->attr;
0142
0143     /* Directories do not have read/write permissions on the media */
0144     if (S_ISDIR(inode->i_mode))
0145         return ADFS_NDA_DIRECTORY;
0146
0147     attr = 0;
0148     mode = ia_mode & asb->s_owner_mask;
0149     if (mode & S_IRUGO)
0150         attr |= ADFS_NDA_OWNER_READ;
0151     if (mode & S_IWUGO)
0152         attr |= ADFS_NDA_OWNER_WRITE;
0153
0154     mode = ia_mode & asb->s_other_mask;
0155     mode &= ~asb->s_owner_mask;
0156     if (mode & S_IRUGO)
0157         attr |= ADFS_NDA_PUBLIC_READ;
0158     if (mode & S_IWUGO)
0159         attr |= ADFS_NDA_PUBLIC_WRITE;
0160
0161     return attr;
0162 }
0163
0164 static const s64 nsec_unix_epoch_diff_risc_os_epoch = 2208988800000000000LL;
0165
0166 /*
0167  * Convert an ADFS time to Unix time.  ADFS has a 40-bit centi-second time
0168  * referenced to 1 Jan 1900 (til 2248) so we need to discard 2208988800 seconds
0169  * of time to convert from RISC OS epoch to Unix epoch.
0170  */
0171 static void
0172 adfs_adfs2unix_time(struct timespec64 *tv, struct inode *inode)
0173 {
0174     unsigned int high, low;
0175     /* 01 Jan 1970 00:00:00 (Unix epoch) as nanoseconds since
0176      * 01 Jan 1900 00:00:00 (RISC OS epoch)
0177      */
0178     s64 nsec;
0179
0180     if (!adfs_inode_is_stamped(inode))
0181         goto cur_time;
0182
0183     high = ADFS_I(inode)->loadaddr & 0xFF; /* top 8 bits of timestamp */
0184     low  = ADFS_I(inode)->execaddr;    /* bottom 32 bits of timestamp */
0185
0186     /* convert 40-bit centi-seconds to 32-bit seconds
0187      * going via nanoseconds to retain precision
0188      */
0189     nsec = (((s64) high << 32) | (s64) low) * 10000000; /* cs to ns */
0190
0191     /* Files dated pre  01 Jan 1970 00:00:00. */
0192     if (nsec < nsec_unix_epoch_diff_risc_os_epoch)
0193         goto too_early;
0194
0195     /* convert from RISC OS to Unix epoch */
0196     nsec -= nsec_unix_epoch_diff_risc_os_epoch;
0197
0198     *tv = ns_to_timespec64(nsec);
0199     return;
0200
0201  cur_time:
0202     *tv = current_time(inode);
0203     return;
0204
0205  too_early:
0206     tv->tv_sec = tv->tv_nsec = 0;
0207     return;
0208 }
0209
0210 /* Convert an Unix time to ADFS time for an entry that is already stamped. */
0211 static void adfs_unix2adfs_time(struct inode *inode,
0212                 const struct timespec64 *ts)
0213 {
0214     s64 cs, nsec = timespec64_to_ns(ts);
0215
0216     /* convert from Unix to RISC OS epoch */
0217     nsec += nsec_unix_epoch_diff_risc_os_epoch;
0218
0219     /* convert from nanoseconds to centiseconds */
0220     cs = div_s64(nsec, 10000000);
0221
0222     cs = clamp_t(s64, cs, 0, 0xffffffffff);
0223
0224     ADFS_I(inode)->loadaddr &= ~0xff;
0225     ADFS_I(inode)->loadaddr |= (cs >> 32) & 0xff;
0226     ADFS_I(inode)->execaddr = cs;
0227 }
0228
0229 /*
0230  * Fill in the inode information from the object information.
0231  *
0232  * Note that this is an inode-less filesystem, so we can't use the inode
0233  * number to reference the metadata on the media.  Instead, we use the
0234  * inode number to hold the object ID, which in turn will tell us where
0235  * the data is held.  We also save the parent object ID, and with these
0236  * two, we can locate the metadata.
0237  *
0238  * This does mean that we rely on an objects parent remaining the same at
0239  * all times - we cannot cope with a cross-directory rename (yet).
0240  */
0241 struct inode *
0242 adfs_iget(struct super_block *sb, struct object_info *obj)
0243 {
0244     struct inode *inode;
0245
0246     inode = new_inode(sb);
0247     if (!inode)
0248         goto out;
0249
0250     inode->i_uid     = ADFS_SB(sb)->s_uid;
0251     inode->i_gid     = ADFS_SB(sb)->s_gid;
0252     inode->i_ino     = obj->indaddr;
0253     inode->i_size    = obj->size;
0254     set_nlink(inode, 2);
0255     inode->i_blocks  = (inode->i_size + sb->s_blocksize - 1) >>
0256                 sb->s_blocksize_bits;
0257
0258     /*
0259      * we need to save the parent directory ID so that
0260      * write_inode can update the directory information
0261      * for this file.  This will need special handling
0262      * for cross-directory renames.
0263      */
0264     ADFS_I(inode)->parent_id = obj->parent_id;
0265     ADFS_I(inode)->indaddr   = obj->indaddr;
0266     ADFS_I(inode)->loadaddr  = obj->loadaddr;
0267     ADFS_I(inode)->execaddr  = obj->execaddr;
0268     ADFS_I(inode)->attr      = obj->attr;
0269
0270     inode->i_mode    = adfs_atts2mode(sb, inode);
0271     adfs_adfs2unix_time(&inode->i_mtime, inode);
0272     inode->i_atime = inode->i_mtime;
0273     inode->i_ctime = inode->i_mtime;
0274
0275     if (S_ISDIR(inode->i_mode)) {
0276         inode->i_op = &adfs_dir_inode_operations;
0277         inode->i_fop    = &adfs_dir_operations;
0278     } else if (S_ISREG(inode->i_mode)) {
0279         inode->i_op = &adfs_file_inode_operations;
0280         inode->i_fop    = &adfs_file_operations;
0281         inode->i_mapping->a_ops = &adfs_aops;
0282         ADFS_I(inode)->mmu_private = inode->i_size;
0283     }
0284
0285     inode_fake_hash(inode);
0286
0287 out:
0288     return inode;
0289 }
0290
0291 /*
0292  * Validate and convert a changed access mode/time to their ADFS equivalents.
0293  * adfs_write_inode will actually write the information back to the directory
0294  * later.
0295  */
0296 int
0297 adfs_notify_change(struct user_namespace *mnt_userns, struct dentry *dentry,
0298            struct iattr *attr)
0299 {
0300     struct inode *inode = d_inode(dentry);
0301     struct super_block *sb = inode->i_sb;
0302     unsigned int ia_valid = attr->ia_valid;
0303     int error;
0304
0305     error = setattr_prepare(&init_user_ns, dentry, attr);
0306
0307     /*
0308      * we can't change the UID or GID of any file -
0309      * we have a global UID/GID in the superblock
0310      */
0311     if ((ia_valid & ATTR_UID && !uid_eq(attr->ia_uid, ADFS_SB(sb)->s_uid)) ||
0312         (ia_valid & ATTR_GID && !gid_eq(attr->ia_gid, ADFS_SB(sb)->s_gid)))
0313         error = -EPERM;
0314
0315     if (error)
0316         goto out;
0317
0318     /* XXX: this is missing some actual on-disk truncation.. */
0319     if (ia_valid & ATTR_SIZE)
0320         truncate_setsize(inode, attr->ia_size);
0321
0322     if (ia_valid & ATTR_MTIME && adfs_inode_is_stamped(inode)) {
0323         adfs_unix2adfs_time(inode, &attr->ia_mtime);
0324         adfs_adfs2unix_time(&inode->i_mtime, inode);
0325     }
0326
0327     /*
0328      * FIXME: should we make these == to i_mtime since we don't
0329      * have the ability to represent them in our filesystem?
0330      */
0331     if (ia_valid & ATTR_ATIME)
0332         inode->i_atime = attr->ia_atime;
0333     if (ia_valid & ATTR_CTIME)
0334         inode->i_ctime = attr->ia_ctime;
0335     if (ia_valid & ATTR_MODE) {
0336         ADFS_I(inode)->attr = adfs_mode2atts(sb, inode, attr->ia_mode);
0337         inode->i_mode = adfs_atts2mode(sb, inode);
0338     }
0339
0340     /*
0341      * FIXME: should we be marking this inode dirty even if
0342      * we don't have any metadata to write back?
0343      */
0344     if (ia_valid & (ATTR_SIZE | ATTR_MTIME | ATTR_MODE))
0345         mark_inode_dirty(inode);
0346 out:
0347     return error;
0348 }
0349
0350 /*
0351  * write an existing inode back to the directory, and therefore the disk.
0352  * The adfs-specific inode data has already been updated by
0353  * adfs_notify_change()
0354  */
0355 int adfs_write_inode(struct inode *inode, struct writeback_control *wbc)
0356 {
0357     struct super_block *sb = inode->i_sb;
0358     struct object_info obj;
0359
0360     obj.indaddr = ADFS_I(inode)->indaddr;
0361     obj.name_len    = 0;
0362     obj.parent_id   = ADFS_I(inode)->parent_id;
0363     obj.loadaddr    = ADFS_I(inode)->loadaddr;
0364     obj.execaddr    = ADFS_I(inode)->execaddr;
0365     obj.attr    = ADFS_I(inode)->attr;
0366     obj.size    = inode->i_size;
0367
0368     return adfs_dir_update(sb, &obj, wbc->sync_mode == WB_SYNC_ALL);
0369 }