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/smp_lock.h>
11#include <linux/buffer_head.h>
12#include <linux/writeback.h>
13#include "adfs.h"
14
15/*
16 * Lookup/Create a block at offset 'block' into 'inode'.  We currently do
17 * not support creation of new blocks, so we return -EIO for this case.
18 */
19static int
20adfs_get_block(struct inode *inode, sector_t block, struct buffer_head *bh,
21	       int create)
22{
23	if (!create) {
24		if (block >= inode->i_blocks)
25			goto abort_toobig;
26
27		block = __adfs_block_map(inode->i_sb, inode->i_ino, block);
28		if (block)
29			map_bh(bh, inode->i_sb, block);
30		return 0;
31	}
32	/* don't support allocation of blocks yet */
33	return -EIO;
34
35abort_toobig:
36	return 0;
37}
38
39static int adfs_writepage(struct page *page, struct writeback_control *wbc)
40{
41	return block_write_full_page(page, adfs_get_block, wbc);
42}
43
44static int adfs_readpage(struct file *file, struct page *page)
45{
46	return block_read_full_page(page, adfs_get_block);
47}
48
49static int adfs_write_begin(struct file *file, struct address_space *mapping,
50			loff_t pos, unsigned len, unsigned flags,
51			struct page **pagep, void **fsdata)
52{
53	int ret;
54
55	*pagep = NULL;
56	ret = cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
57				adfs_get_block,
58				&ADFS_I(mapping->host)->mmu_private);
59	if (unlikely(ret)) {
60		loff_t isize = mapping->host->i_size;
61		if (pos + len > isize)
62			vmtruncate(mapping->host, isize);
63	}
64
65	return ret;
66}
67
68static sector_t _adfs_bmap(struct address_space *mapping, sector_t block)
69{
70	return generic_block_bmap(mapping, block, adfs_get_block);
71}
72
73static const struct address_space_operations adfs_aops = {
74	.readpage	= adfs_readpage,
75	.writepage	= adfs_writepage,
76	.sync_page	= block_sync_page,
77	.write_begin	= adfs_write_begin,
78	.write_end	= generic_write_end,
79	.bmap		= _adfs_bmap
80};
81
82static inline unsigned int
83adfs_filetype(struct inode *inode)
84{
85	unsigned int type;
86
87	if (ADFS_I(inode)->stamped)
88		type = (ADFS_I(inode)->loadaddr >> 8) & 0xfff;
89	else
90		type = (unsigned int) -1;
91
92	return type;
93}
94
95/*
96 * Convert ADFS attributes and filetype to Linux permission.
97 */
98static umode_t
99adfs_atts2mode(struct super_block *sb, struct inode *inode)
100{
101	unsigned int filetype, attr = ADFS_I(inode)->attr;
102	umode_t mode, rmask;
103	struct adfs_sb_info *asb = ADFS_SB(sb);
104
105	if (attr & ADFS_NDA_DIRECTORY) {
106		mode = S_IRUGO & asb->s_owner_mask;
107		return S_IFDIR | S_IXUGO | mode;
108	}
109
110	filetype = adfs_filetype(inode);
111
112	switch (filetype) {
113	case 0xfc0:	/* LinkFS */
114		return S_IFLNK|S_IRWXUGO;
115
116	case 0xfe6:	/* UnixExec */
117		rmask = S_IRUGO | S_IXUGO;
118		break;
119
120	default:
121		rmask = S_IRUGO;
122	}
123
124	mode = S_IFREG;
125
126	if (attr & ADFS_NDA_OWNER_READ)
127		mode |= rmask & asb->s_owner_mask;
128
129	if (attr & ADFS_NDA_OWNER_WRITE)
130		mode |= S_IWUGO & asb->s_owner_mask;
131
132	if (attr & ADFS_NDA_PUBLIC_READ)
133		mode |= rmask & asb->s_other_mask;
134
135	if (attr & ADFS_NDA_PUBLIC_WRITE)
136		mode |= S_IWUGO & asb->s_other_mask;
137	return mode;
138}
139
140/*
141 * Convert Linux permission to ADFS attribute.  We try to do the reverse
142 * of atts2mode, but there is not a 1:1 translation.
143 */
144static int
145adfs_mode2atts(struct super_block *sb, struct inode *inode)
146{
147	umode_t mode;
148	int attr;
149	struct adfs_sb_info *asb = ADFS_SB(sb);
150
151	if (S_ISLNK(inode->i_mode))
152		return ADFS_I(inode)->attr;
153
154	if (S_ISDIR(inode->i_mode))
155		attr = ADFS_NDA_DIRECTORY;
156	else
157		attr = 0;
158
159	mode = inode->i_mode & asb->s_owner_mask;
160	if (mode & S_IRUGO)
161		attr |= ADFS_NDA_OWNER_READ;
162	if (mode & S_IWUGO)
163		attr |= ADFS_NDA_OWNER_WRITE;
164
165	mode = inode->i_mode & asb->s_other_mask;
166	mode &= ~asb->s_owner_mask;
167	if (mode & S_IRUGO)
168		attr |= ADFS_NDA_PUBLIC_READ;
169	if (mode & S_IWUGO)
170		attr |= ADFS_NDA_PUBLIC_WRITE;
171
172	return attr;
173}
174
175/*
176 * Convert an ADFS time to Unix time.  ADFS has a 40-bit centi-second time
177 * referenced to 1 Jan 1900 (til 2248)
178 */
179static void
180adfs_adfs2unix_time(struct timespec *tv, struct inode *inode)
181{
182	unsigned int high, low;
183
184	if (ADFS_I(inode)->stamped == 0)
185		goto cur_time;
186
187	high = ADFS_I(inode)->loadaddr << 24;
188	low  = ADFS_I(inode)->execaddr;
189
190	high |= low >> 8;
191	low  &= 255;
192
193	/* Files dated pre  01 Jan 1970 00:00:00. */
194	if (high < 0x336e996a)
195		goto too_early;
196
197	/* Files dated post 18 Jan 2038 03:14:05. */
198	if (high >= 0x656e9969)
199		goto too_late;
200
201	/* discard 2208988800 (0x336e996a00) seconds of time */
202	high -= 0x336e996a;
203
204	/* convert 40-bit centi-seconds to 32-bit seconds */
205	tv->tv_sec = (((high % 100) << 8) + low) / 100 + (high / 100 << 8);
206	tv->tv_nsec = 0;
207	return;
208
209 cur_time:
210	*tv = CURRENT_TIME_SEC;
211	return;
212
213 too_early:
214	tv->tv_sec = tv->tv_nsec = 0;
215	return;
216
217 too_late:
218	tv->tv_sec = 0x7ffffffd;
219	tv->tv_nsec = 0;
220	return;
221}
222
223/*
224 * Convert an Unix time to ADFS time.  We only do this if the entry has a
225 * time/date stamp already.
226 */
227static void
228adfs_unix2adfs_time(struct inode *inode, unsigned int secs)
229{
230	unsigned int high, low;
231
232	if (ADFS_I(inode)->stamped) {
233		/* convert 32-bit seconds to 40-bit centi-seconds */
234		low  = (secs & 255) * 100;
235		high = (secs / 256) * 100 + (low >> 8) + 0x336e996a;
236
237		ADFS_I(inode)->loadaddr = (high >> 24) |
238				(ADFS_I(inode)->loadaddr & ~0xff);
239		ADFS_I(inode)->execaddr = (low & 255) | (high << 8);
240	}
241}
242
243/*
244 * Fill in the inode information from the object information.
245 *
246 * Note that this is an inode-less filesystem, so we can't use the inode
247 * number to reference the metadata on the media.  Instead, we use the
248 * inode number to hold the object ID, which in turn will tell us where
249 * the data is held.  We also save the parent object ID, and with these
250 * two, we can locate the metadata.
251 *
252 * This does mean that we rely on an objects parent remaining the same at
253 * all times - we cannot cope with a cross-directory rename (yet).
254 */
255struct inode *
256adfs_iget(struct super_block *sb, struct object_info *obj)
257{
258	struct inode *inode;
259
260	inode = new_inode(sb);
261	if (!inode)
262		goto out;
263
264	inode->i_uid	 = ADFS_SB(sb)->s_uid;
265	inode->i_gid	 = ADFS_SB(sb)->s_gid;
266	inode->i_ino	 = obj->file_id;
267	inode->i_size	 = obj->size;
268	inode->i_nlink	 = 2;
269	inode->i_blocks	 = (inode->i_size + sb->s_blocksize - 1) >>
270			    sb->s_blocksize_bits;
271
272	/*
273	 * we need to save the parent directory ID so that
274	 * write_inode can update the directory information
275	 * for this file.  This will need special handling
276	 * for cross-directory renames.
277	 */
278	ADFS_I(inode)->parent_id = obj->parent_id;
279	ADFS_I(inode)->loadaddr  = obj->loadaddr;
280	ADFS_I(inode)->execaddr  = obj->execaddr;
281	ADFS_I(inode)->attr      = obj->attr;
282	ADFS_I(inode)->stamped	  = ((obj->loadaddr & 0xfff00000) == 0xfff00000);
283
284	inode->i_mode	 = adfs_atts2mode(sb, inode);
285	adfs_adfs2unix_time(&inode->i_mtime, inode);
286	inode->i_atime = inode->i_mtime;
287	inode->i_ctime = inode->i_mtime;
288
289	if (S_ISDIR(inode->i_mode)) {
290		inode->i_op	= &adfs_dir_inode_operations;
291		inode->i_fop	= &adfs_dir_operations;
292	} else if (S_ISREG(inode->i_mode)) {
293		inode->i_op	= &adfs_file_inode_operations;
294		inode->i_fop	= &adfs_file_operations;
295		inode->i_mapping->a_ops = &adfs_aops;
296		ADFS_I(inode)->mmu_private = inode->i_size;
297	}
298
299	insert_inode_hash(inode);
300
301out:
302	return inode;
303}
304
305/*
306 * Validate and convert a changed access mode/time to their ADFS equivalents.
307 * adfs_write_inode will actually write the information back to the directory
308 * later.
309 */
310int
311adfs_notify_change(struct dentry *dentry, struct iattr *attr)
312{
313	struct inode *inode = dentry->d_inode;
314	struct super_block *sb = inode->i_sb;
315	unsigned int ia_valid = attr->ia_valid;
316	int error;
317
318	lock_kernel();
319
320	error = inode_change_ok(inode, attr);
321
322	/*
323	 * we can't change the UID or GID of any file -
324	 * we have a global UID/GID in the superblock
325	 */
326	if ((ia_valid & ATTR_UID && attr->ia_uid != ADFS_SB(sb)->s_uid) ||
327	    (ia_valid & ATTR_GID && attr->ia_gid != ADFS_SB(sb)->s_gid))
328		error = -EPERM;
329
330	if (error)
331		goto out;
332
333	if (ia_valid & ATTR_SIZE)
334		truncate_setsize(inode, attr->ia_size);
335
336	if (ia_valid & ATTR_MTIME) {
337		inode->i_mtime = attr->ia_mtime;
338		adfs_unix2adfs_time(inode, attr->ia_mtime.tv_sec);
339	}
340	if (ia_valid & ATTR_ATIME)
341		inode->i_atime = attr->ia_atime;
342	if (ia_valid & ATTR_CTIME)
343		inode->i_ctime = attr->ia_ctime;
344	if (ia_valid & ATTR_MODE) {
345		ADFS_I(inode)->attr = adfs_mode2atts(sb, inode);
346		inode->i_mode = adfs_atts2mode(sb, inode);
347	}
348
349	if (ia_valid & (ATTR_SIZE | ATTR_MTIME | ATTR_MODE))
350		mark_inode_dirty(inode);
351out:
352	unlock_kernel();
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 */
361int 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	int ret;
366
367	lock_kernel();
368	obj.file_id	= inode->i_ino;
369	obj.name_len	= 0;
370	obj.parent_id	= ADFS_I(inode)->parent_id;
371	obj.loadaddr	= ADFS_I(inode)->loadaddr;
372	obj.execaddr	= ADFS_I(inode)->execaddr;
373	obj.attr	= ADFS_I(inode)->attr;
374	obj.size	= inode->i_size;
375
376	ret = adfs_dir_update(sb, &obj, wbc->sync_mode == WB_SYNC_ALL);
377	unlock_kernel();
378	return ret;
379}
380