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
adfs_get_block(struct inode * inode,sector_t block,struct buffer_head * bh,int create)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, inode->i_ino, block);
24 if (block)
25 map_bh(bh, inode->i_sb, block);
26 return 0;
27 }
28 /* don't support allocation of blocks yet */
29 return -EIO;
30
31 abort_toobig:
32 return 0;
33 }
34
adfs_writepage(struct page * page,struct writeback_control * wbc)35 static int adfs_writepage(struct page *page, struct writeback_control *wbc)
36 {
37 return block_write_full_page(page, adfs_get_block, wbc);
38 }
39
adfs_readpage(struct file * file,struct page * page)40 static int adfs_readpage(struct file *file, struct page *page)
41 {
42 return block_read_full_page(page, adfs_get_block);
43 }
44
adfs_write_failed(struct address_space * mapping,loff_t to)45 static void adfs_write_failed(struct address_space *mapping, loff_t to)
46 {
47 struct inode *inode = mapping->host;
48
49 if (to > inode->i_size)
50 truncate_pagecache(inode, inode->i_size);
51 }
52
adfs_write_begin(struct file * file,struct address_space * mapping,loff_t pos,unsigned len,unsigned flags,struct page ** pagep,void ** fsdata)53 static int adfs_write_begin(struct file *file, struct address_space *mapping,
54 loff_t pos, unsigned len, unsigned flags,
55 struct page **pagep, void **fsdata)
56 {
57 int ret;
58
59 *pagep = NULL;
60 ret = cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
61 adfs_get_block,
62 &ADFS_I(mapping->host)->mmu_private);
63 if (unlikely(ret))
64 adfs_write_failed(mapping, pos + len);
65
66 return ret;
67 }
68
_adfs_bmap(struct address_space * mapping,sector_t block)69 static sector_t _adfs_bmap(struct address_space *mapping, sector_t block)
70 {
71 return generic_block_bmap(mapping, block, adfs_get_block);
72 }
73
74 static const struct address_space_operations adfs_aops = {
75 .readpage = adfs_readpage,
76 .writepage = adfs_writepage,
77 .write_begin = adfs_write_begin,
78 .write_end = generic_write_end,
79 .bmap = _adfs_bmap
80 };
81
82 /*
83 * Convert ADFS attributes and filetype to Linux permission.
84 */
85 static umode_t
adfs_atts2mode(struct super_block * sb,struct inode * inode)86 adfs_atts2mode(struct super_block *sb, struct inode *inode)
87 {
88 unsigned int attr = ADFS_I(inode)->attr;
89 umode_t mode, rmask;
90 struct adfs_sb_info *asb = ADFS_SB(sb);
91
92 if (attr & ADFS_NDA_DIRECTORY) {
93 mode = S_IRUGO & asb->s_owner_mask;
94 return S_IFDIR | S_IXUGO | mode;
95 }
96
97 switch (adfs_filetype(ADFS_I(inode)->loadaddr)) {
98 case 0xfc0: /* LinkFS */
99 return S_IFLNK|S_IRWXUGO;
100
101 case 0xfe6: /* UnixExec */
102 rmask = S_IRUGO | S_IXUGO;
103 break;
104
105 default:
106 rmask = S_IRUGO;
107 }
108
109 mode = S_IFREG;
110
111 if (attr & ADFS_NDA_OWNER_READ)
112 mode |= rmask & asb->s_owner_mask;
113
114 if (attr & ADFS_NDA_OWNER_WRITE)
115 mode |= S_IWUGO & asb->s_owner_mask;
116
117 if (attr & ADFS_NDA_PUBLIC_READ)
118 mode |= rmask & asb->s_other_mask;
119
120 if (attr & ADFS_NDA_PUBLIC_WRITE)
121 mode |= S_IWUGO & asb->s_other_mask;
122 return mode;
123 }
124
125 /*
126 * Convert Linux permission to ADFS attribute. We try to do the reverse
127 * of atts2mode, but there is not a 1:1 translation.
128 */
129 static int
adfs_mode2atts(struct super_block * sb,struct inode * inode)130 adfs_mode2atts(struct super_block *sb, struct inode *inode)
131 {
132 umode_t mode;
133 int attr;
134 struct adfs_sb_info *asb = ADFS_SB(sb);
135
136 /* FIXME: should we be able to alter a link? */
137 if (S_ISLNK(inode->i_mode))
138 return ADFS_I(inode)->attr;
139
140 if (S_ISDIR(inode->i_mode))
141 attr = ADFS_NDA_DIRECTORY;
142 else
143 attr = 0;
144
145 mode = inode->i_mode & asb->s_owner_mask;
146 if (mode & S_IRUGO)
147 attr |= ADFS_NDA_OWNER_READ;
148 if (mode & S_IWUGO)
149 attr |= ADFS_NDA_OWNER_WRITE;
150
151 mode = inode->i_mode & asb->s_other_mask;
152 mode &= ~asb->s_owner_mask;
153 if (mode & S_IRUGO)
154 attr |= ADFS_NDA_PUBLIC_READ;
155 if (mode & S_IWUGO)
156 attr |= ADFS_NDA_PUBLIC_WRITE;
157
158 return attr;
159 }
160
161 /*
162 * Convert an ADFS time to Unix time. ADFS has a 40-bit centi-second time
163 * referenced to 1 Jan 1900 (til 2248) so we need to discard 2208988800 seconds
164 * of time to convert from RISC OS epoch to Unix epoch.
165 */
166 static void
adfs_adfs2unix_time(struct timespec64 * tv,struct inode * inode)167 adfs_adfs2unix_time(struct timespec64 *tv, struct inode *inode)
168 {
169 unsigned int high, low;
170 /* 01 Jan 1970 00:00:00 (Unix epoch) as nanoseconds since
171 * 01 Jan 1900 00:00:00 (RISC OS epoch)
172 */
173 static const s64 nsec_unix_epoch_diff_risc_os_epoch =
174 2208988800000000000LL;
175 s64 nsec;
176
177 if (!adfs_inode_is_stamped(inode))
178 goto cur_time;
179
180 high = ADFS_I(inode)->loadaddr & 0xFF; /* top 8 bits of timestamp */
181 low = ADFS_I(inode)->execaddr; /* bottom 32 bits of timestamp */
182
183 /* convert 40-bit centi-seconds to 32-bit seconds
184 * going via nanoseconds to retain precision
185 */
186 nsec = (((s64) high << 32) | (s64) low) * 10000000; /* cs to ns */
187
188 /* Files dated pre 01 Jan 1970 00:00:00. */
189 if (nsec < nsec_unix_epoch_diff_risc_os_epoch)
190 goto too_early;
191
192 /* convert from RISC OS to Unix epoch */
193 nsec -= nsec_unix_epoch_diff_risc_os_epoch;
194
195 *tv = ns_to_timespec64(nsec);
196 return;
197
198 cur_time:
199 *tv = current_time(inode);
200 return;
201
202 too_early:
203 tv->tv_sec = tv->tv_nsec = 0;
204 return;
205 }
206
207 /*
208 * Convert an Unix time to ADFS time. We only do this if the entry has a
209 * time/date stamp already.
210 */
211 static void
adfs_unix2adfs_time(struct inode * inode,unsigned int secs)212 adfs_unix2adfs_time(struct inode *inode, unsigned int secs)
213 {
214 unsigned int high, low;
215
216 if (adfs_inode_is_stamped(inode)) {
217 /* convert 32-bit seconds to 40-bit centi-seconds */
218 low = (secs & 255) * 100;
219 high = (secs / 256) * 100 + (low >> 8) + 0x336e996a;
220
221 ADFS_I(inode)->loadaddr = (high >> 24) |
222 (ADFS_I(inode)->loadaddr & ~0xff);
223 ADFS_I(inode)->execaddr = (low & 255) | (high << 8);
224 }
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 *
adfs_iget(struct super_block * sb,struct object_info * obj)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)->loadaddr = obj->loadaddr;
264 ADFS_I(inode)->execaddr = obj->execaddr;
265 ADFS_I(inode)->attr = obj->attr;
266
267 inode->i_mode = adfs_atts2mode(sb, inode);
268 adfs_adfs2unix_time(&inode->i_mtime, inode);
269 inode->i_atime = inode->i_mtime;
270 inode->i_ctime = inode->i_mtime;
271
272 if (S_ISDIR(inode->i_mode)) {
273 inode->i_op = &adfs_dir_inode_operations;
274 inode->i_fop = &adfs_dir_operations;
275 } else if (S_ISREG(inode->i_mode)) {
276 inode->i_op = &adfs_file_inode_operations;
277 inode->i_fop = &adfs_file_operations;
278 inode->i_mapping->a_ops = &adfs_aops;
279 ADFS_I(inode)->mmu_private = inode->i_size;
280 }
281
282 inode_fake_hash(inode);
283
284 out:
285 return inode;
286 }
287
288 /*
289 * Validate and convert a changed access mode/time to their ADFS equivalents.
290 * adfs_write_inode will actually write the information back to the directory
291 * later.
292 */
293 int
adfs_notify_change(struct dentry * dentry,struct iattr * attr)294 adfs_notify_change(struct dentry *dentry, struct iattr *attr)
295 {
296 struct inode *inode = d_inode(dentry);
297 struct super_block *sb = inode->i_sb;
298 unsigned int ia_valid = attr->ia_valid;
299 int error;
300
301 error = setattr_prepare(dentry, attr);
302
303 /*
304 * we can't change the UID or GID of any file -
305 * we have a global UID/GID in the superblock
306 */
307 if ((ia_valid & ATTR_UID && !uid_eq(attr->ia_uid, ADFS_SB(sb)->s_uid)) ||
308 (ia_valid & ATTR_GID && !gid_eq(attr->ia_gid, ADFS_SB(sb)->s_gid)))
309 error = -EPERM;
310
311 if (error)
312 goto out;
313
314 /* XXX: this is missing some actual on-disk truncation.. */
315 if (ia_valid & ATTR_SIZE)
316 truncate_setsize(inode, attr->ia_size);
317
318 if (ia_valid & ATTR_MTIME) {
319 inode->i_mtime = attr->ia_mtime;
320 adfs_unix2adfs_time(inode, attr->ia_mtime.tv_sec);
321 }
322 /*
323 * FIXME: should we make these == to i_mtime since we don't
324 * have the ability to represent them in our filesystem?
325 */
326 if (ia_valid & ATTR_ATIME)
327 inode->i_atime = attr->ia_atime;
328 if (ia_valid & ATTR_CTIME)
329 inode->i_ctime = attr->ia_ctime;
330 if (ia_valid & ATTR_MODE) {
331 ADFS_I(inode)->attr = adfs_mode2atts(sb, inode);
332 inode->i_mode = adfs_atts2mode(sb, inode);
333 }
334
335 /*
336 * FIXME: should we be marking this inode dirty even if
337 * we don't have any metadata to write back?
338 */
339 if (ia_valid & (ATTR_SIZE | ATTR_MTIME | ATTR_MODE))
340 mark_inode_dirty(inode);
341 out:
342 return error;
343 }
344
345 /*
346 * write an existing inode back to the directory, and therefore the disk.
347 * The adfs-specific inode data has already been updated by
348 * adfs_notify_change()
349 */
adfs_write_inode(struct inode * inode,struct writeback_control * wbc)350 int adfs_write_inode(struct inode *inode, struct writeback_control *wbc)
351 {
352 struct super_block *sb = inode->i_sb;
353 struct object_info obj;
354 int ret;
355
356 obj.indaddr = inode->i_ino;
357 obj.name_len = 0;
358 obj.parent_id = ADFS_I(inode)->parent_id;
359 obj.loadaddr = ADFS_I(inode)->loadaddr;
360 obj.execaddr = ADFS_I(inode)->execaddr;
361 obj.attr = ADFS_I(inode)->attr;
362 obj.size = inode->i_size;
363
364 ret = adfs_dir_update(sb, &obj, wbc->sync_mode == WB_SYNC_ALL);
365 return ret;
366 }
367