1/*
2 * inode.c
3 *
4 * Copyright (c) 1999 Al Smith
5 *
6 * Portions derived from work (c) 1995,1996 Christian Vogelgsang,
7 *              and from work (c) 1998 Mike Shaver.
8 */
9
10#include <linux/efs_fs.h>
11#include <linux/efs_fs_sb.h>
12#include <linux/buffer_head.h>
13#include <linux/module.h>
14#include <linux/fs.h>
15
16static int efs_readpage(struct file *file, struct page *page)
17{
18	return block_read_full_page(page,efs_get_block);
19}
20static sector_t _efs_bmap(struct address_space *mapping, sector_t block)
21{
22	return generic_block_bmap(mapping,block,efs_get_block);
23}
24static const struct address_space_operations efs_aops = {
25	.readpage = efs_readpage,
26	.sync_page = block_sync_page,
27	.bmap = _efs_bmap
28};
29
30static inline void extent_copy(efs_extent *src, efs_extent *dst) {
31	/*
32	 * this is slightly evil. it doesn't just copy
33	 * efs_extent from src to dst, it also mangles
34	 * the bits so that dst ends up in cpu byte-order.
35	 */
36
37	dst->cooked.ex_magic  =  (unsigned int) src->raw[0];
38	dst->cooked.ex_bn     = ((unsigned int) src->raw[1] << 16) |
39				((unsigned int) src->raw[2] <<  8) |
40				((unsigned int) src->raw[3] <<  0);
41	dst->cooked.ex_length =  (unsigned int) src->raw[4];
42	dst->cooked.ex_offset = ((unsigned int) src->raw[5] << 16) |
43				((unsigned int) src->raw[6] <<  8) |
44				((unsigned int) src->raw[7] <<  0);
45	return;
46}
47
48void efs_read_inode(struct inode *inode)
49{
50	int i, inode_index;
51	dev_t device;
52	u32 rdev;
53	struct buffer_head *bh;
54	struct efs_sb_info    *sb = SUPER_INFO(inode->i_sb);
55	struct efs_inode_info *in = INODE_INFO(inode);
56	efs_block_t block, offset;
57	struct efs_dinode *efs_inode;
58
59	/*
60	** EFS layout:
61	**
62	** |   cylinder group    |   cylinder group    |   cylinder group ..etc
63	** |inodes|data          |inodes|data          |inodes|data       ..etc
64	**
65	** work out the inode block index, (considering initially that the
66	** inodes are stored as consecutive blocks). then work out the block
67	** number of that inode given the above layout, and finally the
68	** offset of the inode within that block.
69	*/
70
71	inode_index = inode->i_ino /
72		(EFS_BLOCKSIZE / sizeof(struct efs_dinode));
73
74	block = sb->fs_start + sb->first_block +
75		(sb->group_size * (inode_index / sb->inode_blocks)) +
76		(inode_index % sb->inode_blocks);
77
78	offset = (inode->i_ino %
79			(EFS_BLOCKSIZE / sizeof(struct efs_dinode))) *
80		sizeof(struct efs_dinode);
81
82	bh = sb_bread(inode->i_sb, block);
83	if (!bh) {
84		printk(KERN_WARNING "EFS: bread() failed at block %d\n", block);
85		goto read_inode_error;
86	}
87
88	efs_inode = (struct efs_dinode *) (bh->b_data + offset);
89
90	inode->i_mode  = be16_to_cpu(efs_inode->di_mode);
91	inode->i_nlink = be16_to_cpu(efs_inode->di_nlink);
92	inode->i_uid   = (uid_t)be16_to_cpu(efs_inode->di_uid);
93	inode->i_gid   = (gid_t)be16_to_cpu(efs_inode->di_gid);
94	inode->i_size  = be32_to_cpu(efs_inode->di_size);
95	inode->i_atime.tv_sec = be32_to_cpu(efs_inode->di_atime);
96	inode->i_mtime.tv_sec = be32_to_cpu(efs_inode->di_mtime);
97	inode->i_ctime.tv_sec = be32_to_cpu(efs_inode->di_ctime);
98	inode->i_atime.tv_nsec = inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec = 0;
99
100	/* this is the number of blocks in the file */
101	if (inode->i_size == 0) {
102		inode->i_blocks = 0;
103	} else {
104		inode->i_blocks = ((inode->i_size - 1) >> EFS_BLOCKSIZE_BITS) + 1;
105	}
106
107	rdev = be16_to_cpu(efs_inode->di_u.di_dev.odev);
108	if (rdev == 0xffff) {
109		rdev = be32_to_cpu(efs_inode->di_u.di_dev.ndev);
110		if (sysv_major(rdev) > 0xfff)
111			device = 0;
112		else
113			device = MKDEV(sysv_major(rdev), sysv_minor(rdev));
114	} else
115		device = old_decode_dev(rdev);
116
117	/* get the number of extents for this object */
118	in->numextents = be16_to_cpu(efs_inode->di_numextents);
119	in->lastextent = 0;
120
121	/* copy the extents contained within the inode to memory */
122	for(i = 0; i < EFS_DIRECTEXTENTS; i++) {
123		extent_copy(&(efs_inode->di_u.di_extents[i]), &(in->extents[i]));
124		if (i < in->numextents && in->extents[i].cooked.ex_magic != 0) {
125			printk(KERN_WARNING "EFS: extent %d has bad magic number in inode %lu\n", i, inode->i_ino);
126			brelse(bh);
127			goto read_inode_error;
128		}
129	}
130
131	brelse(bh);
132
133#ifdef DEBUG
134	printk(KERN_DEBUG "EFS: read_inode(): inode %lu, extents %d, mode %o\n",
135		inode->i_ino, in->numextents, inode->i_mode);
136#endif
137
138	switch (inode->i_mode & S_IFMT) {
139		case S_IFDIR:
140			inode->i_op = &efs_dir_inode_operations;
141			inode->i_fop = &efs_dir_operations;
142			break;
143		case S_IFREG:
144			inode->i_fop = &generic_ro_fops;
145			inode->i_data.a_ops = &efs_aops;
146			break;
147		case S_IFLNK:
148			inode->i_op = &page_symlink_inode_operations;
149			inode->i_data.a_ops = &efs_symlink_aops;
150			break;
151		case S_IFCHR:
152		case S_IFBLK:
153		case S_IFIFO:
154			init_special_inode(inode, inode->i_mode, device);
155			break;
156		default:
157			printk(KERN_WARNING "EFS: unsupported inode mode %o\n", inode->i_mode);
158			goto read_inode_error;
159			break;
160	}
161
162	return;
163
164read_inode_error:
165	printk(KERN_WARNING "EFS: failed to read inode %lu\n", inode->i_ino);
166	make_bad_inode(inode);
167
168	return;
169}
170
171static inline efs_block_t
172efs_extent_check(efs_extent *ptr, efs_block_t block, struct efs_sb_info *sb) {
173	efs_block_t start;
174	efs_block_t length;
175	efs_block_t offset;
176
177	/*
178	 * given an extent and a logical block within a file,
179	 * can this block be found within this extent ?
180	 */
181	start  = ptr->cooked.ex_bn;
182	length = ptr->cooked.ex_length;
183	offset = ptr->cooked.ex_offset;
184
185	if ((block >= offset) && (block < offset+length)) {
186		return(sb->fs_start + start + block - offset);
187	} else {
188		return 0;
189	}
190}
191
192efs_block_t efs_map_block(struct inode *inode, efs_block_t block) {
193	struct efs_sb_info    *sb = SUPER_INFO(inode->i_sb);
194	struct efs_inode_info *in = INODE_INFO(inode);
195	struct buffer_head    *bh = NULL;
196
197	int cur, last, first = 1;
198	int ibase, ioffset, dirext, direxts, indext, indexts;
199	efs_block_t iblock, result = 0, lastblock = 0;
200	efs_extent ext, *exts;
201
202	last = in->lastextent;
203
204	if (in->numextents <= EFS_DIRECTEXTENTS) {
205		/* first check the last extent we returned */
206		if ((result = efs_extent_check(&in->extents[last], block, sb)))
207			return result;
208
209		/* if we only have one extent then nothing can be found */
210		if (in->numextents == 1) {
211			printk(KERN_ERR "EFS: map_block() failed to map (1 extent)\n");
212			return 0;
213		}
214
215		direxts = in->numextents;
216
217		/*
218		 * check the stored extents in the inode
219		 * start with next extent and check forwards
220		 */
221		for(dirext = 1; dirext < direxts; dirext++) {
222			cur = (last + dirext) % in->numextents;
223			if ((result = efs_extent_check(&in->extents[cur], block, sb))) {
224				in->lastextent = cur;
225				return result;
226			}
227		}
228
229		printk(KERN_ERR "EFS: map_block() failed to map block %u (dir)\n", block);
230		return 0;
231	}
232
233#ifdef DEBUG
234	printk(KERN_DEBUG "EFS: map_block(): indirect search for logical block %u\n", block);
235#endif
236	direxts = in->extents[0].cooked.ex_offset;
237	indexts = in->numextents;
238
239	for(indext = 0; indext < indexts; indext++) {
240		cur = (last + indext) % indexts;
241
242		/*
243		 * work out which direct extent contains `cur'.
244		 *
245		 * also compute ibase: i.e. the number of the first
246		 * indirect extent contained within direct extent `cur'.
247		 *
248		 */
249		ibase = 0;
250		for(dirext = 0; cur < ibase && dirext < direxts; dirext++) {
251			ibase += in->extents[dirext].cooked.ex_length *
252				(EFS_BLOCKSIZE / sizeof(efs_extent));
253		}
254
255		if (dirext == direxts) {
256			/* should never happen */
257			printk(KERN_ERR "EFS: couldn't find direct extent for indirect extent %d (block %u)\n", cur, block);
258			if (bh) brelse(bh);
259			return 0;
260		}
261
262		/* work out block number and offset of this indirect extent */
263		iblock = sb->fs_start + in->extents[dirext].cooked.ex_bn +
264			(cur - ibase) /
265			(EFS_BLOCKSIZE / sizeof(efs_extent));
266		ioffset = (cur - ibase) %
267			(EFS_BLOCKSIZE / sizeof(efs_extent));
268
269		if (first || lastblock != iblock) {
270			if (bh) brelse(bh);
271
272			bh = sb_bread(inode->i_sb, iblock);
273			if (!bh) {
274				printk(KERN_ERR "EFS: bread() failed at block %d\n", iblock);
275				return 0;
276			}
277#ifdef DEBUG
278			printk(KERN_DEBUG "EFS: map_block(): read indirect extent block %d\n", iblock);
279#endif
280			first = 0;
281			lastblock = iblock;
282		}
283
284		exts = (efs_extent *) bh->b_data;
285
286		extent_copy(&(exts[ioffset]), &ext);
287
288		if (ext.cooked.ex_magic != 0) {
289			printk(KERN_ERR "EFS: extent %d has bad magic number in block %d\n", cur, iblock);
290			if (bh) brelse(bh);
291			return 0;
292		}
293
294		if ((result = efs_extent_check(&ext, block, sb))) {
295			if (bh) brelse(bh);
296			in->lastextent = cur;
297			return result;
298		}
299	}
300	if (bh) brelse(bh);
301	printk(KERN_ERR "EFS: map_block() failed to map block %u (indir)\n", block);
302	return 0;
303}
304
305MODULE_LICENSE("GPL");
306