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 */
15static int
16adfs_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(sb: inode->i_sb, indaddr: ADFS_I(inode)->indaddr,
24 block);
25 if (block)
26 map_bh(bh, sb: inode->i_sb, block);
27 return 0;
28 }
29 /* don't support allocation of blocks yet */
30 return -EIO;
31
32abort_toobig:
33 return 0;
34}
35
36static int adfs_writepage(struct page *page, struct writeback_control *wbc)
37{
38 return block_write_full_page(page, get_block: adfs_get_block, wbc);
39}
40
41static int adfs_read_folio(struct file *file, struct folio *folio)
42{
43 return block_read_full_folio(folio, adfs_get_block);
44}
45
46static 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, new: inode->i_size);
52}
53
54static int adfs_write_begin(struct file *file, struct address_space *mapping,
55 loff_t pos, unsigned len,
56 struct page **pagep, void **fsdata)
57{
58 int ret;
59
60 *pagep = NULL;
61 ret = cont_write_begin(file, mapping, pos, len, pagep, fsdata,
62 adfs_get_block,
63 &ADFS_I(inode: mapping->host)->mmu_private);
64 if (unlikely(ret))
65 adfs_write_failed(mapping, to: pos + len);
66
67 return ret;
68}
69
70static sector_t _adfs_bmap(struct address_space *mapping, sector_t block)
71{
72 return generic_block_bmap(mapping, block, adfs_get_block);
73}
74
75static const struct address_space_operations adfs_aops = {
76 .dirty_folio = block_dirty_folio,
77 .invalidate_folio = block_invalidate_folio,
78 .read_folio = adfs_read_folio,
79 .writepage = adfs_writepage,
80 .write_begin = adfs_write_begin,
81 .write_end = generic_write_end,
82 .bmap = _adfs_bmap
83};
84
85/*
86 * Convert ADFS attributes and filetype to Linux permission.
87 */
88static umode_t
89adfs_atts2mode(struct super_block *sb, struct inode *inode)
90{
91 unsigned int attr = ADFS_I(inode)->attr;
92 umode_t mode, rmask;
93 struct adfs_sb_info *asb = ADFS_SB(sb);
94
95 if (attr & ADFS_NDA_DIRECTORY) {
96 mode = S_IRUGO & asb->s_owner_mask;
97 return S_IFDIR | S_IXUGO | mode;
98 }
99
100 switch (adfs_filetype(loadaddr: ADFS_I(inode)->loadaddr)) {
101 case 0xfc0: /* LinkFS */
102 return S_IFLNK|S_IRWXUGO;
103
104 case 0xfe6: /* UnixExec */
105 rmask = S_IRUGO | S_IXUGO;
106 break;
107
108 default:
109 rmask = S_IRUGO;
110 }
111
112 mode = S_IFREG;
113
114 if (attr & ADFS_NDA_OWNER_READ)
115 mode |= rmask & asb->s_owner_mask;
116
117 if (attr & ADFS_NDA_OWNER_WRITE)
118 mode |= S_IWUGO & asb->s_owner_mask;
119
120 if (attr & ADFS_NDA_PUBLIC_READ)
121 mode |= rmask & asb->s_other_mask;
122
123 if (attr & ADFS_NDA_PUBLIC_WRITE)
124 mode |= S_IWUGO & asb->s_other_mask;
125 return mode;
126}
127
128/*
129 * Convert Linux permission to ADFS attribute. We try to do the reverse
130 * of atts2mode, but there is not a 1:1 translation.
131 */
132static int adfs_mode2atts(struct super_block *sb, struct inode *inode,
133 umode_t ia_mode)
134{
135 struct adfs_sb_info *asb = ADFS_SB(sb);
136 umode_t mode;
137 int attr;
138
139 /* FIXME: should we be able to alter a link? */
140 if (S_ISLNK(inode->i_mode))
141 return ADFS_I(inode)->attr;
142
143 /* Directories do not have read/write permissions on the media */
144 if (S_ISDIR(inode->i_mode))
145 return ADFS_NDA_DIRECTORY;
146
147 attr = 0;
148 mode = ia_mode & asb->s_owner_mask;
149 if (mode & S_IRUGO)
150 attr |= ADFS_NDA_OWNER_READ;
151 if (mode & S_IWUGO)
152 attr |= ADFS_NDA_OWNER_WRITE;
153
154 mode = ia_mode & asb->s_other_mask;
155 mode &= ~asb->s_owner_mask;
156 if (mode & S_IRUGO)
157 attr |= ADFS_NDA_PUBLIC_READ;
158 if (mode & S_IWUGO)
159 attr |= ADFS_NDA_PUBLIC_WRITE;
160
161 return attr;
162}
163
164static const s64 nsec_unix_epoch_diff_risc_os_epoch = 2208988800000000000LL;
165
166/*
167 * Convert an ADFS time to Unix time. ADFS has a 40-bit centi-second time
168 * referenced to 1 Jan 1900 (til 2248) so we need to discard 2208988800 seconds
169 * of time to convert from RISC OS epoch to Unix epoch.
170 */
171static void
172adfs_adfs2unix_time(struct timespec64 *tv, struct inode *inode)
173{
174 unsigned int high, low;
175 /* 01 Jan 1970 00:00:00 (Unix epoch) as nanoseconds since
176 * 01 Jan 1900 00:00:00 (RISC OS epoch)
177 */
178 s64 nsec;
179
180 if (!adfs_inode_is_stamped(inode))
181 goto cur_time;
182
183 high = ADFS_I(inode)->loadaddr & 0xFF; /* top 8 bits of timestamp */
184 low = ADFS_I(inode)->execaddr; /* bottom 32 bits of timestamp */
185
186 /* convert 40-bit centi-seconds to 32-bit seconds
187 * going via nanoseconds to retain precision
188 */
189 nsec = (((s64) high << 32) | (s64) low) * 10000000; /* cs to ns */
190
191 /* Files dated pre 01 Jan 1970 00:00:00. */
192 if (nsec < nsec_unix_epoch_diff_risc_os_epoch)
193 goto too_early;
194
195 /* convert from RISC OS to Unix epoch */
196 nsec -= nsec_unix_epoch_diff_risc_os_epoch;
197
198 *tv = ns_to_timespec64(nsec);
199 return;
200
201 cur_time:
202 *tv = current_time(inode);
203 return;
204
205 too_early:
206 tv->tv_sec = tv->tv_nsec = 0;
207 return;
208}
209
210/* Convert an Unix time to ADFS time for an entry that is already stamped. */
211static void adfs_unix2adfs_time(struct inode *inode,
212 const struct timespec64 *ts)
213{
214 s64 cs, nsec = timespec64_to_ns(ts);
215
216 /* convert from Unix to RISC OS epoch */
217 nsec += nsec_unix_epoch_diff_risc_os_epoch;
218
219 /* convert from nanoseconds to centiseconds */
220 cs = div_s64(dividend: nsec, divisor: 10000000);
221
222 cs = clamp_t(s64, cs, 0, 0xffffffffff);
223
224 ADFS_I(inode)->loadaddr &= ~0xff;
225 ADFS_I(inode)->loadaddr |= (cs >> 32) & 0xff;
226 ADFS_I(inode)->execaddr = cs;
227}
228
229/*
230 * Fill in the inode information from the object information.
231 *
232 * Note that this is an inode-less filesystem, so we can't use the inode
233 * number to reference the metadata on the media. Instead, we use the
234 * inode number to hold the object ID, which in turn will tell us where
235 * the data is held. We also save the parent object ID, and with these
236 * two, we can locate the metadata.
237 *
238 * This does mean that we rely on an objects parent remaining the same at
239 * all times - we cannot cope with a cross-directory rename (yet).
240 */
241struct inode *
242adfs_iget(struct super_block *sb, struct object_info *obj)
243{
244 struct inode *inode;
245 struct timespec64 ts;
246
247 inode = new_inode(sb);
248 if (!inode)
249 goto out;
250
251 inode->i_uid = ADFS_SB(sb)->s_uid;
252 inode->i_gid = ADFS_SB(sb)->s_gid;
253 inode->i_ino = obj->indaddr;
254 inode->i_size = obj->size;
255 set_nlink(inode, nlink: 2);
256 inode->i_blocks = (inode->i_size + sb->s_blocksize - 1) >>
257 sb->s_blocksize_bits;
258
259 /*
260 * we need to save the parent directory ID so that
261 * write_inode can update the directory information
262 * for this file. This will need special handling
263 * for cross-directory renames.
264 */
265 ADFS_I(inode)->parent_id = obj->parent_id;
266 ADFS_I(inode)->indaddr = obj->indaddr;
267 ADFS_I(inode)->loadaddr = obj->loadaddr;
268 ADFS_I(inode)->execaddr = obj->execaddr;
269 ADFS_I(inode)->attr = obj->attr;
270
271 inode->i_mode = adfs_atts2mode(sb, inode);
272 adfs_adfs2unix_time(tv: &ts, inode);
273 inode_set_atime_to_ts(inode, ts);
274 inode_set_mtime_to_ts(inode, ts);
275 inode_set_ctime_to_ts(inode, ts);
276
277 if (S_ISDIR(inode->i_mode)) {
278 inode->i_op = &adfs_dir_inode_operations;
279 inode->i_fop = &adfs_dir_operations;
280 } else if (S_ISREG(inode->i_mode)) {
281 inode->i_op = &adfs_file_inode_operations;
282 inode->i_fop = &adfs_file_operations;
283 inode->i_mapping->a_ops = &adfs_aops;
284 ADFS_I(inode)->mmu_private = inode->i_size;
285 }
286
287 inode_fake_hash(inode);
288
289out:
290 return inode;
291}
292
293/*
294 * Validate and convert a changed access mode/time to their ADFS equivalents.
295 * adfs_write_inode will actually write the information back to the directory
296 * later.
297 */
298int
299adfs_notify_change(struct mnt_idmap *idmap, struct dentry *dentry,
300 struct iattr *attr)
301{
302 struct inode *inode = d_inode(dentry);
303 struct super_block *sb = inode->i_sb;
304 unsigned int ia_valid = attr->ia_valid;
305 int error;
306
307 error = setattr_prepare(&nop_mnt_idmap, dentry, attr);
308
309 /*
310 * we can't change the UID or GID of any file -
311 * we have a global UID/GID in the superblock
312 */
313 if ((ia_valid & ATTR_UID && !uid_eq(left: attr->ia_uid, right: ADFS_SB(sb)->s_uid)) ||
314 (ia_valid & ATTR_GID && !gid_eq(left: attr->ia_gid, right: ADFS_SB(sb)->s_gid)))
315 error = -EPERM;
316
317 if (error)
318 goto out;
319
320 /* XXX: this is missing some actual on-disk truncation.. */
321 if (ia_valid & ATTR_SIZE)
322 truncate_setsize(inode, newsize: attr->ia_size);
323
324 if (ia_valid & ATTR_MTIME && adfs_inode_is_stamped(inode)) {
325 adfs_unix2adfs_time(inode, ts: &attr->ia_mtime);
326 adfs_adfs2unix_time(tv: &attr->ia_mtime, inode);
327 inode_set_mtime_to_ts(inode, ts: attr->ia_mtime);
328 }
329
330 /*
331 * FIXME: should we make these == to i_mtime since we don't
332 * have the ability to represent them in our filesystem?
333 */
334 if (ia_valid & ATTR_ATIME)
335 inode_set_atime_to_ts(inode, ts: attr->ia_atime);
336 if (ia_valid & ATTR_CTIME)
337 inode_set_ctime_to_ts(inode, ts: attr->ia_ctime);
338 if (ia_valid & ATTR_MODE) {
339 ADFS_I(inode)->attr = adfs_mode2atts(sb, inode, ia_mode: attr->ia_mode);
340 inode->i_mode = adfs_atts2mode(sb, inode);
341 }
342
343 /*
344 * FIXME: should we be marking this inode dirty even if
345 * we don't have any metadata to write back?
346 */
347 if (ia_valid & (ATTR_SIZE | ATTR_MTIME | ATTR_MODE))
348 mark_inode_dirty(inode);
349out:
350 return error;
351}
352
353/*
354 * write an existing inode back to the directory, and therefore the disk.
355 * The adfs-specific inode data has already been updated by
356 * adfs_notify_change()
357 */
358int adfs_write_inode(struct inode *inode, struct writeback_control *wbc)
359{
360 struct super_block *sb = inode->i_sb;
361 struct object_info obj;
362
363 obj.indaddr = ADFS_I(inode)->indaddr;
364 obj.name_len = 0;
365 obj.parent_id = ADFS_I(inode)->parent_id;
366 obj.loadaddr = ADFS_I(inode)->loadaddr;
367 obj.execaddr = ADFS_I(inode)->execaddr;
368 obj.attr = ADFS_I(inode)->attr;
369 obj.size = inode->i_size;
370
371 return adfs_dir_update(sb, obj: &obj, wait: wbc->sync_mode == WB_SYNC_ALL);
372}
373

source code of linux/fs/adfs/inode.c