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1/*
2 * linux/fs/adfs/inode.c
3 *
4 * Copyright (C) 1997-1999 Russell King
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 */
10#include <linux/buffer_head.h>
11#include <linux/writeback.h>
12#include "adfs.h"
13
14/*
15 * Lookup/Create a block at offset 'block' into 'inode'. We currently do
16 * not support creation of new blocks, so we return -EIO for this case.
17 */
18static int
19adfs_get_block(struct inode *inode, sector_t block, struct buffer_head *bh,
20 int create)
21{
22 if (!create) {
23 if (block >= inode->i_blocks)
24 goto abort_toobig;
25
26 block = __adfs_block_map(inode->i_sb, inode->i_ino, block);
27 if (block)
28 map_bh(bh, inode->i_sb, block);
29 return 0;
30 }
31 /* don't support allocation of blocks yet */
32 return -EIO;
33
34abort_toobig:
35 return 0;
36}
37
38static int adfs_writepage(struct page *page, struct writeback_control *wbc)
39{
40 return block_write_full_page(page, adfs_get_block, wbc);
41}
42
43static int adfs_readpage(struct file *file, struct page *page)
44{
45 return block_read_full_page(page, adfs_get_block);
46}
47
48static int adfs_write_begin(struct file *file, struct address_space *mapping,
49 loff_t pos, unsigned len, unsigned flags,
50 struct page **pagep, void **fsdata)
51{
52 int ret;
53
54 *pagep = NULL;
55 ret = cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
56 adfs_get_block,
57 &ADFS_I(mapping->host)->mmu_private);
58 if (unlikely(ret)) {
59 loff_t isize = mapping->host->i_size;
60 if (pos + len > isize)
61 vmtruncate(mapping->host, isize);
62 }
63
64 return ret;
65}
66
67static sector_t _adfs_bmap(struct address_space *mapping, sector_t block)
68{
69 return generic_block_bmap(mapping, block, adfs_get_block);
70}
71
72static const struct address_space_operations adfs_aops = {
73 .readpage = adfs_readpage,
74 .writepage = adfs_writepage,
75 .write_begin = adfs_write_begin,
76 .write_end = generic_write_end,
77 .bmap = _adfs_bmap
78};
79
80/*
81 * Convert ADFS attributes and filetype to Linux permission.
82 */
83static umode_t
84adfs_atts2mode(struct super_block *sb, struct inode *inode)
85{
86 unsigned int attr = ADFS_I(inode)->attr;
87 umode_t mode, rmask;
88 struct adfs_sb_info *asb = ADFS_SB(sb);
89
90 if (attr & ADFS_NDA_DIRECTORY) {
91 mode = S_IRUGO & asb->s_owner_mask;
92 return S_IFDIR | S_IXUGO | mode;
93 }
94
95 switch (ADFS_I(inode)->filetype) {
96 case 0xfc0: /* LinkFS */
97 return S_IFLNK|S_IRWXUGO;
98
99 case 0xfe6: /* UnixExec */
100 rmask = S_IRUGO | S_IXUGO;
101 break;
102
103 default:
104 rmask = S_IRUGO;
105 }
106
107 mode = S_IFREG;
108
109 if (attr & ADFS_NDA_OWNER_READ)
110 mode |= rmask & asb->s_owner_mask;
111
112 if (attr & ADFS_NDA_OWNER_WRITE)
113 mode |= S_IWUGO & asb->s_owner_mask;
114
115 if (attr & ADFS_NDA_PUBLIC_READ)
116 mode |= rmask & asb->s_other_mask;
117
118 if (attr & ADFS_NDA_PUBLIC_WRITE)
119 mode |= S_IWUGO & asb->s_other_mask;
120 return mode;
121}
122
123/*
124 * Convert Linux permission to ADFS attribute. We try to do the reverse
125 * of atts2mode, but there is not a 1:1 translation.
126 */
127static int
128adfs_mode2atts(struct super_block *sb, struct inode *inode)
129{
130 umode_t mode;
131 int attr;
132 struct adfs_sb_info *asb = ADFS_SB(sb);
133
134 /* FIXME: should we be able to alter a link? */
135 if (S_ISLNK(inode->i_mode))
136 return ADFS_I(inode)->attr;
137
138 if (S_ISDIR(inode->i_mode))
139 attr = ADFS_NDA_DIRECTORY;
140 else
141 attr = 0;
142
143 mode = inode->i_mode & asb->s_owner_mask;
144 if (mode & S_IRUGO)
145 attr |= ADFS_NDA_OWNER_READ;
146 if (mode & S_IWUGO)
147 attr |= ADFS_NDA_OWNER_WRITE;
148
149 mode = inode->i_mode & asb->s_other_mask;
150 mode &= ~asb->s_owner_mask;
151 if (mode & S_IRUGO)
152 attr |= ADFS_NDA_PUBLIC_READ;
153 if (mode & S_IWUGO)
154 attr |= ADFS_NDA_PUBLIC_WRITE;
155
156 return attr;
157}
158
159/*
160 * Convert an ADFS time to Unix time. ADFS has a 40-bit centi-second time
161 * referenced to 1 Jan 1900 (til 2248) so we need to discard 2208988800 seconds
162 * of time to convert from RISC OS epoch to Unix epoch.
163 */
164static void
165adfs_adfs2unix_time(struct timespec *tv, struct inode *inode)
166{
167 unsigned int high, low;
168 /* 01 Jan 1970 00:00:00 (Unix epoch) as nanoseconds since
169 * 01 Jan 1900 00:00:00 (RISC OS epoch)
170 */
171 static const s64 nsec_unix_epoch_diff_risc_os_epoch =
172 2208988800000000000LL;
173 s64 nsec;
174
175 if (ADFS_I(inode)->stamped == 0)
176 goto cur_time;
177
178 high = ADFS_I(inode)->loadaddr & 0xFF; /* top 8 bits of timestamp */
179 low = ADFS_I(inode)->execaddr; /* bottom 32 bits of timestamp */
180
181 /* convert 40-bit centi-seconds to 32-bit seconds
182 * going via nanoseconds to retain precision
183 */
184 nsec = (((s64) high << 32) | (s64) low) * 10000000; /* cs to ns */
185
186 /* Files dated pre 01 Jan 1970 00:00:00. */
187 if (nsec < nsec_unix_epoch_diff_risc_os_epoch)
188 goto too_early;
189
190 /* convert from RISC OS to Unix epoch */
191 nsec -= nsec_unix_epoch_diff_risc_os_epoch;
192
193 *tv = ns_to_timespec(nsec);
194 return;
195
196 cur_time:
197 *tv = CURRENT_TIME;
198 return;
199
200 too_early:
201 tv->tv_sec = tv->tv_nsec = 0;
202 return;
203}
204
205/*
206 * Convert an Unix time to ADFS time. We only do this if the entry has a
207 * time/date stamp already.
208 */
209static void
210adfs_unix2adfs_time(struct inode *inode, unsigned int secs)
211{
212 unsigned int high, low;
213
214 if (ADFS_I(inode)->stamped) {
215 /* convert 32-bit seconds to 40-bit centi-seconds */
216 low = (secs & 255) * 100;
217 high = (secs / 256) * 100 + (low >> 8) + 0x336e996a;
218
219 ADFS_I(inode)->loadaddr = (high >> 24) |
220 (ADFS_I(inode)->loadaddr & ~0xff);
221 ADFS_I(inode)->execaddr = (low & 255) | (high << 8);
222 }
223}
224
225/*
226 * Fill in the inode information from the object information.
227 *
228 * Note that this is an inode-less filesystem, so we can't use the inode
229 * number to reference the metadata on the media. Instead, we use the
230 * inode number to hold the object ID, which in turn will tell us where
231 * the data is held. We also save the parent object ID, and with these
232 * two, we can locate the metadata.
233 *
234 * This does mean that we rely on an objects parent remaining the same at
235 * all times - we cannot cope with a cross-directory rename (yet).
236 */
237struct inode *
238adfs_iget(struct super_block *sb, struct object_info *obj)
239{
240 struct inode *inode;
241
242 inode = new_inode(sb);
243 if (!inode)
244 goto out;
245
246 inode->i_uid = ADFS_SB(sb)->s_uid;
247 inode->i_gid = ADFS_SB(sb)->s_gid;
248 inode->i_ino = obj->file_id;
249 inode->i_size = obj->size;
250 set_nlink(inode, 2);
251 inode->i_blocks = (inode->i_size + sb->s_blocksize - 1) >>
252 sb->s_blocksize_bits;
253
254 /*
255 * we need to save the parent directory ID so that
256 * write_inode can update the directory information
257 * for this file. This will need special handling
258 * for cross-directory renames.
259 */
260 ADFS_I(inode)->parent_id = obj->parent_id;
261 ADFS_I(inode)->loadaddr = obj->loadaddr;
262 ADFS_I(inode)->execaddr = obj->execaddr;
263 ADFS_I(inode)->attr = obj->attr;
264 ADFS_I(inode)->filetype = obj->filetype;
265 ADFS_I(inode)->stamped = ((obj->loadaddr & 0xfff00000) == 0xfff00000);
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 insert_inode_hash(inode);
283
284out:
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 */
293int
294adfs_notify_change(struct dentry *dentry, struct iattr *attr)
295{
296 struct inode *inode = dentry->d_inode;
297 struct super_block *sb = inode->i_sb;
298 unsigned int ia_valid = attr->ia_valid;
299 int error;
300
301 error = inode_change_ok(inode, 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 && attr->ia_uid != ADFS_SB(sb)->s_uid) ||
308 (ia_valid & ATTR_GID && 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);
341out:
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 */
350int 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.file_id = 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}