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