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(sb: inode->i_sb, indaddr: ADFS_I(inode)->indaddr, |
25 | block); |
26 | if (block) |
27 | map_bh(bh, sb: 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, get_block: 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, new: 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(inode: mapping->host)->mmu_private); |
66 | if (unlikely(ret)) |
67 | adfs_write_failed(mapping, to: 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(loadaddr: 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(dividend: nsec, divisor: 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, nlink: 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(tv: &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(left: attr->ia_uid, right: ADFS_SB(sb)->s_uid)) || |
317 | (ia_valid & ATTR_GID && !gid_eq(left: attr->ia_gid, right: 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, newsize: attr->ia_size); |
326 | |
327 | if (ia_valid & ATTR_MTIME && adfs_inode_is_stamped(inode)) { |
328 | adfs_unix2adfs_time(inode, ts: &attr->ia_mtime); |
329 | adfs_adfs2unix_time(tv: &attr->ia_mtime, inode); |
330 | inode_set_mtime_to_ts(inode, ts: 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, ts: attr->ia_atime); |
339 | if (ia_valid & ATTR_CTIME) |
340 | inode_set_ctime_to_ts(inode, ts: attr->ia_ctime); |
341 | if (ia_valid & ATTR_MODE) { |
342 | ADFS_I(inode)->attr = adfs_mode2atts(sb, inode, ia_mode: 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: &obj, wait: wbc->sync_mode == WB_SYNC_ALL); |
375 | } |
376 | |