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 page **pagep, void **fsdata)
59 {
60 int ret;
61
62 *pagep = NULL;
63 ret = cont_write_begin(file, mapping, pos, len, pagep, fsdata,
64 adfs_get_block,
65 &ADFS_I(mapping->host)->mmu_private);
66 if (unlikely(ret))
67 adfs_write_failed(mapping, pos + len);
68
69 return ret;
70 }
71
72 static sector_t _adfs_bmap(struct address_space *mapping, sector_t block)
73 {
74 return generic_block_bmap(mapping, block, adfs_get_block);
75 }
76
77 static const struct address_space_operations adfs_aops = {
78 .dirty_folio = block_dirty_folio,
79 .invalidate_folio = block_invalidate_folio,
80 .read_folio = adfs_read_folio,
81 .writepages = adfs_writepages,
82 .write_begin = adfs_write_begin,
83 .write_end = generic_write_end,
84 .migrate_folio = buffer_migrate_folio,
85 .bmap = _adfs_bmap,
86 };
87
88 /*
89 * Convert ADFS attributes and filetype to Linux permission.
90 */
91 static umode_t
92 adfs_atts2mode(struct super_block *sb, struct inode *inode)
93 {
94 unsigned int attr = ADFS_I(inode)->attr;
95 umode_t mode, rmask;
96 struct adfs_sb_info *asb = ADFS_SB(sb);
97
98 if (attr & ADFS_NDA_DIRECTORY) {
99 mode = S_IRUGO & asb->s_owner_mask;
100 return S_IFDIR | S_IXUGO | mode;
101 }
102
103 switch (adfs_filetype(ADFS_I(inode)->loadaddr)) {
104 case 0xfc0: /* LinkFS */
105 return S_IFLNK|S_IRWXUGO;
106
107 case 0xfe6: /* UnixExec */
108 rmask = S_IRUGO | S_IXUGO;
109 break;
110
111 default:
112 rmask = S_IRUGO;
113 }
114
115 mode = S_IFREG;
116
117 if (attr & ADFS_NDA_OWNER_READ)
118 mode |= rmask & asb->s_owner_mask;
119
120 if (attr & ADFS_NDA_OWNER_WRITE)
121 mode |= S_IWUGO & asb->s_owner_mask;
122
123 if (attr & ADFS_NDA_PUBLIC_READ)
124 mode |= rmask & asb->s_other_mask;
125
126 if (attr & ADFS_NDA_PUBLIC_WRITE)
127 mode |= S_IWUGO & asb->s_other_mask;
128 return mode;
129 }
130
131 /*
132 * Convert Linux permission to ADFS attribute. We try to do the reverse
133 * of atts2mode, but there is not a 1:1 translation.
134 */
135 static int adfs_mode2atts(struct super_block *sb, struct inode *inode,
136 umode_t ia_mode)
137 {
138 struct adfs_sb_info *asb = ADFS_SB(sb);
139 umode_t mode;
140 int attr;
141
142 /* FIXME: should we be able to alter a link? */
143 if (S_ISLNK(inode->i_mode))
144 return ADFS_I(inode)->attr;
145
146 /* Directories do not have read/write permissions on the media */
147 if (S_ISDIR(inode->i_mode))
148 return ADFS_NDA_DIRECTORY;
149
150 attr = 0;
151 mode = ia_mode & asb->s_owner_mask;
152 if (mode & S_IRUGO)
153 attr |= ADFS_NDA_OWNER_READ;
154 if (mode & S_IWUGO)
155 attr |= ADFS_NDA_OWNER_WRITE;
156
157 mode = ia_mode & asb->s_other_mask;
158 mode &= ~asb->s_owner_mask;
159 if (mode & S_IRUGO)
160 attr |= ADFS_NDA_PUBLIC_READ;
161 if (mode & S_IWUGO)
162 attr |= ADFS_NDA_PUBLIC_WRITE;
163
164 return attr;
165 }
166
167 static const s64 nsec_unix_epoch_diff_risc_os_epoch = 2208988800000000000LL;
168
169 /*
170 * Convert an ADFS time to Unix time. ADFS has a 40-bit centi-second time
171 * referenced to 1 Jan 1900 (til 2248) so we need to discard 2208988800 seconds
172 * of time to convert from RISC OS epoch to Unix epoch.
173 */
174 static void
175 adfs_adfs2unix_time(struct timespec64 *tv, struct inode *inode)
176 {
177 unsigned int high, low;
178 /* 01 Jan 1970 00:00:00 (Unix epoch) as nanoseconds since
179 * 01 Jan 1900 00:00:00 (RISC OS epoch)
180 */
181 s64 nsec;
182
183 if (!adfs_inode_is_stamped(inode))
184 goto cur_time;
185
186 high = ADFS_I(inode)->loadaddr & 0xFF; /* top 8 bits of timestamp */
187 low = ADFS_I(inode)->execaddr; /* bottom 32 bits of timestamp */
188
189 /* convert 40-bit centi-seconds to 32-bit seconds
190 * going via nanoseconds to retain precision
191 */
192 nsec = (((s64) high << 32) | (s64) low) * 10000000; /* cs to ns */
193
194 /* Files dated pre 01 Jan 1970 00:00:00. */
195 if (nsec < nsec_unix_epoch_diff_risc_os_epoch)
196 goto too_early;
197
198 /* convert from RISC OS to Unix epoch */
199 nsec -= nsec_unix_epoch_diff_risc_os_epoch;
200
201 *tv = ns_to_timespec64(nsec);
202 return;
203
204 cur_time:
205 *tv = current_time(inode);
206 return;
207
208 too_early:
209 tv->tv_sec = tv->tv_nsec = 0;
210 return;
211 }
212
213 /* Convert an Unix time to ADFS time for an entry that is already stamped. */
214 static void adfs_unix2adfs_time(struct inode *inode,
215 const struct timespec64 *ts)
216 {
217 s64 cs, nsec = timespec64_to_ns(ts);
218
219 /* convert from Unix to RISC OS epoch */
220 nsec += nsec_unix_epoch_diff_risc_os_epoch;
221
222 /* convert from nanoseconds to centiseconds */
223 cs = div_s64(nsec, 10000000);
224
225 cs = clamp_t(s64, cs, 0, 0xffffffffff);
226
227 ADFS_I(inode)->loadaddr &= ~0xff;
228 ADFS_I(inode)->loadaddr |= (cs >> 32) & 0xff;
229 ADFS_I(inode)->execaddr = cs;
230 }
231
232 /*
233 * Fill in the inode information from the object information.
234 *
235 * Note that this is an inode-less filesystem, so we can't use the inode
236 * number to reference the metadata on the media. Instead, we use the
237 * inode number to hold the object ID, which in turn will tell us where
238 * the data is held. We also save the parent object ID, and with these
239 * two, we can locate the metadata.
240 *
241 * This does mean that we rely on an objects parent remaining the same at
242 * all times - we cannot cope with a cross-directory rename (yet).
243 */
244 struct inode *
245 adfs_iget(struct super_block *sb, struct object_info *obj)
246 {
247 struct inode *inode;
248 struct timespec64 ts;
249
250 inode = new_inode(sb);
251 if (!inode)
252 goto out;
253
254 inode->i_uid = ADFS_SB(sb)->s_uid;
255 inode->i_gid = ADFS_SB(sb)->s_gid;
256 inode->i_ino = obj->indaddr;
257 inode->i_size = obj->size;
258 set_nlink(inode, 2);
259 inode->i_blocks = (inode->i_size + sb->s_blocksize - 1) >>
260 sb->s_blocksize_bits;
261
262 /*
263 * we need to save the parent directory ID so that
264 * write_inode can update the directory information
265 * for this file. This will need special handling
266 * for cross-directory renames.
267 */
268 ADFS_I(inode)->parent_id = obj->parent_id;
269 ADFS_I(inode)->indaddr = obj->indaddr;
270 ADFS_I(inode)->loadaddr = obj->loadaddr;
271 ADFS_I(inode)->execaddr = obj->execaddr;
272 ADFS_I(inode)->attr = obj->attr;
273
274 inode->i_mode = adfs_atts2mode(sb, inode);
275 adfs_adfs2unix_time(&ts, inode);
276 inode_set_atime_to_ts(inode, ts);
277 inode_set_mtime_to_ts(inode, ts);
278 inode_set_ctime_to_ts(inode, ts);
279
280 if (S_ISDIR(inode->i_mode)) {
281 inode->i_op = &adfs_dir_inode_operations;
282 inode->i_fop = &adfs_dir_operations;
283 } else if (S_ISREG(inode->i_mode)) {
284 inode->i_op = &adfs_file_inode_operations;
285 inode->i_fop = &adfs_file_operations;
286 inode->i_mapping->a_ops = &adfs_aops;
287 ADFS_I(inode)->mmu_private = inode->i_size;
288 }
289
290 inode_fake_hash(inode);
291
292 out:
293 return inode;
294 }
295
296 /*
297 * Validate and convert a changed access mode/time to their ADFS equivalents.
298 * adfs_write_inode will actually write the information back to the directory
299 * later.
300 */
301 int
302 adfs_notify_change(struct mnt_idmap *idmap, struct dentry *dentry,
303 struct iattr *attr)
304 {
305 struct inode *inode = d_inode(dentry);
306 struct super_block *sb = inode->i_sb;
307 unsigned int ia_valid = attr->ia_valid;
308 int error;
309
310 error = setattr_prepare(&nop_mnt_idmap, dentry, attr);
311
312 /*
313 * we can't change the UID or GID of any file -
314 * we have a global UID/GID in the superblock
315 */
316 if ((ia_valid & ATTR_UID && !uid_eq(attr->ia_uid, ADFS_SB(sb)->s_uid)) ||
317 (ia_valid & ATTR_GID && !gid_eq(attr->ia_gid, ADFS_SB(sb)->s_gid)))
318 error = -EPERM;
319
320 if (error)
321 goto out;
322
323 /* XXX: this is missing some actual on-disk truncation.. */
324 if (ia_valid & ATTR_SIZE)
325 truncate_setsize(inode, attr->ia_size);
326
327 if (ia_valid & ATTR_MTIME && adfs_inode_is_stamped(inode)) {
328 adfs_unix2adfs_time(inode, &attr->ia_mtime);
329 adfs_adfs2unix_time(&attr->ia_mtime, inode);
330 inode_set_mtime_to_ts(inode, attr->ia_mtime);
331 }
332
333 /*
334 * FIXME: should we make these == to i_mtime since we don't
335 * have the ability to represent them in our filesystem?
336 */
337 if (ia_valid & ATTR_ATIME)
338 inode_set_atime_to_ts(inode, attr->ia_atime);
339 if (ia_valid & ATTR_CTIME)
340 inode_set_ctime_to_ts(inode, attr->ia_ctime);
341 if (ia_valid & ATTR_MODE) {
342 ADFS_I(inode)->attr = adfs_mode2atts(sb, inode, attr->ia_mode);
343 inode->i_mode = adfs_atts2mode(sb, inode);
344 }
345
346 /*
347 * FIXME: should we be marking this inode dirty even if
348 * we don't have any metadata to write back?
349 */
350 if (ia_valid & (ATTR_SIZE | ATTR_MTIME | ATTR_MODE))
351 mark_inode_dirty(inode);
352 out:
353 return error;
354 }
355
356 /*
357 * write an existing inode back to the directory, and therefore the disk.
358 * The adfs-specific inode data has already been updated by
359 * adfs_notify_change()
360 */
361 int adfs_write_inode(struct inode *inode, struct writeback_control *wbc)
362 {
363 struct super_block *sb = inode->i_sb;
364 struct object_info obj;
365
366 obj.indaddr = ADFS_I(inode)->indaddr;
367 obj.name_len = 0;
368 obj.parent_id = ADFS_I(inode)->parent_id;
369 obj.loadaddr = ADFS_I(inode)->loadaddr;
370 obj.execaddr = ADFS_I(inode)->execaddr;
371 obj.attr = ADFS_I(inode)->attr;
372 obj.size = inode->i_size;
373
374 return adfs_dir_update(sb, &obj, wbc->sync_mode == WB_SYNC_ALL);
375 }
376
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