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 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, inode->i_size);
54}
55
56static int adfs_write_begin(struct file *file, struct address_space *mapping,
57			loff_t pos, unsigned len, unsigned flags,
58			struct page **pagep, void **fsdata)
59{
60	int ret;
61
62	*pagep = NULL;
63	ret = cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
64				adfs_get_block,
65				&ADFS_I(mapping->host)->mmu_private);
66	if (unlikely(ret))
67		adfs_write_failed(mapping, pos + len);
68
69	return ret;
70}
71
72static sector_t _adfs_bmap(struct address_space *mapping, sector_t block)
73{
74	return generic_block_bmap(mapping, block, adfs_get_block);
75}
76
77static const struct address_space_operations adfs_aops = {
78	.readpage	= adfs_readpage,
79	.writepage	= adfs_writepage,
80	.write_begin	= adfs_write_begin,
81	.write_end	= generic_write_end,
82	.bmap		= _adfs_bmap
83};
84
85/*
86 * Convert ADFS attributes and filetype to Linux permission.
87 */
88static umode_t
89adfs_atts2mode(struct super_block *sb, struct inode *inode)
90{
91	unsigned int attr = ADFS_I(inode)->attr;
92	umode_t mode, rmask;
93	struct adfs_sb_info *asb = ADFS_SB(sb);
94
95	if (attr & ADFS_NDA_DIRECTORY) {
96		mode = S_IRUGO & asb->s_owner_mask;
97		return S_IFDIR | S_IXUGO | mode;
98	}
99
100	switch (ADFS_I(inode)->filetype) {
101	case 0xfc0:	/* LinkFS */
102		return S_IFLNK|S_IRWXUGO;
103
104	case 0xfe6:	/* UnixExec */
105		rmask = S_IRUGO | S_IXUGO;
106		break;
107
108	default:
109		rmask = S_IRUGO;
110	}
111
112	mode = S_IFREG;
113
114	if (attr & ADFS_NDA_OWNER_READ)
115		mode |= rmask & asb->s_owner_mask;
116
117	if (attr & ADFS_NDA_OWNER_WRITE)
118		mode |= S_IWUGO & asb->s_owner_mask;
119
120	if (attr & ADFS_NDA_PUBLIC_READ)
121		mode |= rmask & asb->s_other_mask;
122
123	if (attr & ADFS_NDA_PUBLIC_WRITE)
124		mode |= S_IWUGO & asb->s_other_mask;
125	return mode;
126}
127
128/*
129 * Convert Linux permission to ADFS attribute.  We try to do the reverse
130 * of atts2mode, but there is not a 1:1 translation.
131 */
132static int
133adfs_mode2atts(struct super_block *sb, struct inode *inode)
134{
135	umode_t mode;
136	int attr;
137	struct adfs_sb_info *asb = ADFS_SB(sb);
138
139	/* FIXME: should we be able to alter a link? */
140	if (S_ISLNK(inode->i_mode))
141		return ADFS_I(inode)->attr;
142
143	if (S_ISDIR(inode->i_mode))
144		attr = ADFS_NDA_DIRECTORY;
145	else
146		attr = 0;
147
148	mode = inode->i_mode & asb->s_owner_mask;
149	if (mode & S_IRUGO)
150		attr |= ADFS_NDA_OWNER_READ;
151	if (mode & S_IWUGO)
152		attr |= ADFS_NDA_OWNER_WRITE;
153
154	mode = inode->i_mode & asb->s_other_mask;
155	mode &= ~asb->s_owner_mask;
156	if (mode & S_IRUGO)
157		attr |= ADFS_NDA_PUBLIC_READ;
158	if (mode & S_IWUGO)
159		attr |= ADFS_NDA_PUBLIC_WRITE;
160
161	return attr;
162}
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 */
169static void
170adfs_adfs2unix_time(struct timespec *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	static const s64 nsec_unix_epoch_diff_risc_os_epoch =
177							2208988800000000000LL;
178	s64 nsec;
179
180	if (ADFS_I(inode)->stamped == 0)
181		goto cur_time;
182
183	high = ADFS_I(inode)->loadaddr & 0xFF; /* top 8 bits of timestamp */
184	low  = ADFS_I(inode)->execaddr;    /* bottom 32 bits of timestamp */
185
186	/* convert 40-bit centi-seconds to 32-bit seconds
187	 * going via nanoseconds to retain precision
188	 */
189	nsec = (((s64) high << 32) | (s64) low) * 10000000; /* cs to ns */
190
191	/* Files dated pre  01 Jan 1970 00:00:00. */
192	if (nsec < nsec_unix_epoch_diff_risc_os_epoch)
193		goto too_early;
194
195	/* convert from RISC OS to Unix epoch */
196	nsec -= nsec_unix_epoch_diff_risc_os_epoch;
197
198	*tv = ns_to_timespec(nsec);
199	return;
200
201 cur_time:
202	*tv = CURRENT_TIME;
203	return;
204
205 too_early:
206	tv->tv_sec = tv->tv_nsec = 0;
207	return;
208}
209
210/*
211 * Convert an Unix time to ADFS time.  We only do this if the entry has a
212 * time/date stamp already.
213 */
214static void
215adfs_unix2adfs_time(struct inode *inode, unsigned int secs)
216{
217	unsigned int high, low;
218
219	if (ADFS_I(inode)->stamped) {
220		/* convert 32-bit seconds to 40-bit centi-seconds */
221		low  = (secs & 255) * 100;
222		high = (secs / 256) * 100 + (low >> 8) + 0x336e996a;
223
224		ADFS_I(inode)->loadaddr = (high >> 24) |
225				(ADFS_I(inode)->loadaddr & ~0xff);
226		ADFS_I(inode)->execaddr = (low & 255) | (high << 8);
227	}
228}
229
230/*
231 * Fill in the inode information from the object information.
232 *
233 * Note that this is an inode-less filesystem, so we can't use the inode
234 * number to reference the metadata on the media.  Instead, we use the
235 * inode number to hold the object ID, which in turn will tell us where
236 * the data is held.  We also save the parent object ID, and with these
237 * two, we can locate the metadata.
238 *
239 * This does mean that we rely on an objects parent remaining the same at
240 * all times - we cannot cope with a cross-directory rename (yet).
241 */
242struct inode *
243adfs_iget(struct super_block *sb, struct object_info *obj)
244{
245	struct inode *inode;
246
247	inode = new_inode(sb);
248	if (!inode)
249		goto out;
250
251	inode->i_uid	 = ADFS_SB(sb)->s_uid;
252	inode->i_gid	 = ADFS_SB(sb)->s_gid;
253	inode->i_ino	 = obj->file_id;
254	inode->i_size	 = obj->size;
255	set_nlink(inode, 2);
256	inode->i_blocks	 = (inode->i_size + sb->s_blocksize - 1) >>
257			    sb->s_blocksize_bits;
258
259	/*
260	 * we need to save the parent directory ID so that
261	 * write_inode can update the directory information
262	 * for this file.  This will need special handling
263	 * for cross-directory renames.
264	 */
265	ADFS_I(inode)->parent_id = obj->parent_id;
266	ADFS_I(inode)->loadaddr  = obj->loadaddr;
267	ADFS_I(inode)->execaddr  = obj->execaddr;
268	ADFS_I(inode)->attr      = obj->attr;
269	ADFS_I(inode)->filetype  = obj->filetype;
270	ADFS_I(inode)->stamped   = ((obj->loadaddr & 0xfff00000) == 0xfff00000);
271
272	inode->i_mode	 = adfs_atts2mode(sb, inode);
273	adfs_adfs2unix_time(&inode->i_mtime, inode);
274	inode->i_atime = inode->i_mtime;
275	inode->i_ctime = inode->i_mtime;
276
277	if (S_ISDIR(inode->i_mode)) {
278		inode->i_op	= &adfs_dir_inode_operations;
279		inode->i_fop	= &adfs_dir_operations;
280	} else if (S_ISREG(inode->i_mode)) {
281		inode->i_op	= &adfs_file_inode_operations;
282		inode->i_fop	= &adfs_file_operations;
283		inode->i_mapping->a_ops = &adfs_aops;
284		ADFS_I(inode)->mmu_private = inode->i_size;
285	}
286
287	insert_inode_hash(inode);
288
289out:
290	return inode;
291}
292
293/*
294 * Validate and convert a changed access mode/time to their ADFS equivalents.
295 * adfs_write_inode will actually write the information back to the directory
296 * later.
297 */
298int
299adfs_notify_change(struct dentry *dentry, struct iattr *attr)
300{
301	struct inode *inode = d_inode(dentry);
302	struct super_block *sb = inode->i_sb;
303	unsigned int ia_valid = attr->ia_valid;
304	int error;
305
306	error = inode_change_ok(inode, attr);
307
308	/*
309	 * we can't change the UID or GID of any file -
310	 * we have a global UID/GID in the superblock
311	 */
312	if ((ia_valid & ATTR_UID && !uid_eq(attr->ia_uid, ADFS_SB(sb)->s_uid)) ||
313	    (ia_valid & ATTR_GID && !gid_eq(attr->ia_gid, ADFS_SB(sb)->s_gid)))
314		error = -EPERM;
315
316	if (error)
317		goto out;
318
319	/* XXX: this is missing some actual on-disk truncation.. */
320	if (ia_valid & ATTR_SIZE)
321		truncate_setsize(inode, attr->ia_size);
322
323	if (ia_valid & ATTR_MTIME) {
324		inode->i_mtime = attr->ia_mtime;
325		adfs_unix2adfs_time(inode, attr->ia_mtime.tv_sec);
326	}
327	/*
328	 * FIXME: should we make these == to i_mtime since we don't
329	 * have the ability to represent them in our filesystem?
330	 */
331	if (ia_valid & ATTR_ATIME)
332		inode->i_atime = attr->ia_atime;
333	if (ia_valid & ATTR_CTIME)
334		inode->i_ctime = attr->ia_ctime;
335	if (ia_valid & ATTR_MODE) {
336		ADFS_I(inode)->attr = adfs_mode2atts(sb, inode);
337		inode->i_mode = adfs_atts2mode(sb, inode);
338	}
339
340	/*
341	 * FIXME: should we be marking this inode dirty even if
342	 * we don't have any metadata to write back?
343	 */
344	if (ia_valid & (ATTR_SIZE | ATTR_MTIME | ATTR_MODE))
345		mark_inode_dirty(inode);
346out:
347	return error;
348}
349
350/*
351 * write an existing inode back to the directory, and therefore the disk.
352 * The adfs-specific inode data has already been updated by
353 * adfs_notify_change()
354 */
355int adfs_write_inode(struct inode *inode, struct writeback_control *wbc)
356{
357	struct super_block *sb = inode->i_sb;
358	struct object_info obj;
359	int ret;
360
361	obj.file_id	= inode->i_ino;
362	obj.name_len	= 0;
363	obj.parent_id	= ADFS_I(inode)->parent_id;
364	obj.loadaddr	= ADFS_I(inode)->loadaddr;
365	obj.execaddr	= ADFS_I(inode)->execaddr;
366	obj.attr	= ADFS_I(inode)->attr;
367	obj.size	= inode->i_size;
368
369	ret = adfs_dir_update(sb, &obj, wbc->sync_mode == WB_SYNC_ALL);
370	return ret;
371}
372