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/buffer_head.h>
11#include <linux/module.h>
12#include <linux/fs.h>
13#include "efs.h"
14#include <linux/efs_fs_sb.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	.bmap = _efs_bmap
27};
28
29static inline void extent_copy(efs_extent *src, efs_extent *dst) {
30	/*
31	 * this is slightly evil. it doesn't just copy
32	 * efs_extent from src to dst, it also mangles
33	 * the bits so that dst ends up in cpu byte-order.
34	 */
35
36	dst->cooked.ex_magic  =  (unsigned int) src->raw[0];
37	dst->cooked.ex_bn     = ((unsigned int) src->raw[1] << 16) |
38				((unsigned int) src->raw[2] <<  8) |
39				((unsigned int) src->raw[3] <<  0);
40	dst->cooked.ex_length =  (unsigned int) src->raw[4];
41	dst->cooked.ex_offset = ((unsigned int) src->raw[5] << 16) |
42				((unsigned int) src->raw[6] <<  8) |
43				((unsigned int) src->raw[7] <<  0);
44	return;
45}
46
47struct inode *efs_iget(struct super_block *super, unsigned long ino)
48{
49	int i, inode_index;
50	dev_t device;
51	u32 rdev;
52	struct buffer_head *bh;
53	struct efs_sb_info    *sb = SUPER_INFO(super);
54	struct efs_inode_info *in;
55	efs_block_t block, offset;
56	struct efs_dinode *efs_inode;
57	struct inode *inode;
58
59	inode = iget_locked(super, ino);
60	if (!inode)
61		return ERR_PTR(-ENOMEM);
62	if (!(inode->i_state & I_NEW))
63		return inode;
64
65	in = INODE_INFO(inode);
66
67	/*
68	** EFS layout:
69	**
70	** |   cylinder group    |   cylinder group    |   cylinder group ..etc
71	** |inodes|data          |inodes|data          |inodes|data       ..etc
72	**
73	** work out the inode block index, (considering initially that the
74	** inodes are stored as consecutive blocks). then work out the block
75	** number of that inode given the above layout, and finally the
76	** offset of the inode within that block.
77	*/
78
79	inode_index = inode->i_ino /
80		(EFS_BLOCKSIZE / sizeof(struct efs_dinode));
81
82	block = sb->fs_start + sb->first_block +
83		(sb->group_size * (inode_index / sb->inode_blocks)) +
84		(inode_index % sb->inode_blocks);
85
86	offset = (inode->i_ino %
87			(EFS_BLOCKSIZE / sizeof(struct efs_dinode))) *
88		sizeof(struct efs_dinode);
89
90	bh = sb_bread(inode->i_sb, block);
91	if (!bh) {
92		pr_warn("%s() failed at block %d\n", __func__, block);
93		goto read_inode_error;
94	}
95
96	efs_inode = (struct efs_dinode *) (bh->b_data + offset);
97
98	inode->i_mode  = be16_to_cpu(efs_inode->di_mode);
99	set_nlink(inode, be16_to_cpu(efs_inode->di_nlink));
100	i_uid_write(inode, (uid_t)be16_to_cpu(efs_inode->di_uid));
101	i_gid_write(inode, (gid_t)be16_to_cpu(efs_inode->di_gid));
102	inode->i_size  = be32_to_cpu(efs_inode->di_size);
103	inode->i_atime.tv_sec = be32_to_cpu(efs_inode->di_atime);
104	inode->i_mtime.tv_sec = be32_to_cpu(efs_inode->di_mtime);
105	inode->i_ctime.tv_sec = be32_to_cpu(efs_inode->di_ctime);
106	inode->i_atime.tv_nsec = inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec = 0;
107
108	/* this is the number of blocks in the file */
109	if (inode->i_size == 0) {
110		inode->i_blocks = 0;
111	} else {
112		inode->i_blocks = ((inode->i_size - 1) >> EFS_BLOCKSIZE_BITS) + 1;
113	}
114
115	rdev = be16_to_cpu(efs_inode->di_u.di_dev.odev);
116	if (rdev == 0xffff) {
117		rdev = be32_to_cpu(efs_inode->di_u.di_dev.ndev);
118		if (sysv_major(rdev) > 0xfff)
119			device = 0;
120		else
121			device = MKDEV(sysv_major(rdev), sysv_minor(rdev));
122	} else
123		device = old_decode_dev(rdev);
124
125	/* get the number of extents for this object */
126	in->numextents = be16_to_cpu(efs_inode->di_numextents);
127	in->lastextent = 0;
128
129	/* copy the extents contained within the inode to memory */
130	for(i = 0; i < EFS_DIRECTEXTENTS; i++) {
131		extent_copy(&(efs_inode->di_u.di_extents[i]), &(in->extents[i]));
132		if (i < in->numextents && in->extents[i].cooked.ex_magic != 0) {
133			pr_warn("extent %d has bad magic number in inode %lu\n",
134				i, inode->i_ino);
135			brelse(bh);
136			goto read_inode_error;
137		}
138	}
139
140	brelse(bh);
141	pr_debug("efs_iget(): inode %lu, extents %d, mode %o\n",
142		 inode->i_ino, in->numextents, inode->i_mode);
143	switch (inode->i_mode & S_IFMT) {
144		case S_IFDIR:
145			inode->i_op = &efs_dir_inode_operations;
146			inode->i_fop = &efs_dir_operations;
147			break;
148		case S_IFREG:
149			inode->i_fop = &generic_ro_fops;
150			inode->i_data.a_ops = &efs_aops;
151			break;
152		case S_IFLNK:
153			inode->i_op = &page_symlink_inode_operations;
154			inode->i_data.a_ops = &efs_symlink_aops;
155			break;
156		case S_IFCHR:
157		case S_IFBLK:
158		case S_IFIFO:
159			init_special_inode(inode, inode->i_mode, device);
160			break;
161		default:
162			pr_warn("unsupported inode mode %o\n", inode->i_mode);
163			goto read_inode_error;
164			break;
165	}
166
167	unlock_new_inode(inode);
168	return inode;
169
170read_inode_error:
171	pr_warn("failed to read inode %lu\n", inode->i_ino);
172	iget_failed(inode);
173	return ERR_PTR(-EIO);
174}
175
176static inline efs_block_t
177efs_extent_check(efs_extent *ptr, efs_block_t block, struct efs_sb_info *sb) {
178	efs_block_t start;
179	efs_block_t length;
180	efs_block_t offset;
181
182	/*
183	 * given an extent and a logical block within a file,
184	 * can this block be found within this extent ?
185	 */
186	start  = ptr->cooked.ex_bn;
187	length = ptr->cooked.ex_length;
188	offset = ptr->cooked.ex_offset;
189
190	if ((block >= offset) && (block < offset+length)) {
191		return(sb->fs_start + start + block - offset);
192	} else {
193		return 0;
194	}
195}
196
197efs_block_t efs_map_block(struct inode *inode, efs_block_t block) {
198	struct efs_sb_info    *sb = SUPER_INFO(inode->i_sb);
199	struct efs_inode_info *in = INODE_INFO(inode);
200	struct buffer_head    *bh = NULL;
201
202	int cur, last, first = 1;
203	int ibase, ioffset, dirext, direxts, indext, indexts;
204	efs_block_t iblock, result = 0, lastblock = 0;
205	efs_extent ext, *exts;
206
207	last = in->lastextent;
208
209	if (in->numextents <= EFS_DIRECTEXTENTS) {
210		/* first check the last extent we returned */
211		if ((result = efs_extent_check(&in->extents[last], block, sb)))
212			return result;
213
214		/* if we only have one extent then nothing can be found */
215		if (in->numextents == 1) {
216			pr_err("%s() failed to map (1 extent)\n", __func__);
217			return 0;
218		}
219
220		direxts = in->numextents;
221
222		/*
223		 * check the stored extents in the inode
224		 * start with next extent and check forwards
225		 */
226		for(dirext = 1; dirext < direxts; dirext++) {
227			cur = (last + dirext) % in->numextents;
228			if ((result = efs_extent_check(&in->extents[cur], block, sb))) {
229				in->lastextent = cur;
230				return result;
231			}
232		}
233
234		pr_err("%s() failed to map block %u (dir)\n", __func__, block);
235		return 0;
236	}
237
238	pr_debug("%s(): indirect search for logical block %u\n",
239		 __func__, block);
240	direxts = in->extents[0].cooked.ex_offset;
241	indexts = in->numextents;
242
243	for(indext = 0; indext < indexts; indext++) {
244		cur = (last + indext) % indexts;
245
246		/*
247		 * work out which direct extent contains `cur'.
248		 *
249		 * also compute ibase: i.e. the number of the first
250		 * indirect extent contained within direct extent `cur'.
251		 *
252		 */
253		ibase = 0;
254		for(dirext = 0; cur < ibase && dirext < direxts; dirext++) {
255			ibase += in->extents[dirext].cooked.ex_length *
256				(EFS_BLOCKSIZE / sizeof(efs_extent));
257		}
258
259		if (dirext == direxts) {
260			/* should never happen */
261			pr_err("couldn't find direct extent for indirect extent %d (block %u)\n",
262			       cur, block);
263			if (bh) brelse(bh);
264			return 0;
265		}
266
267		/* work out block number and offset of this indirect extent */
268		iblock = sb->fs_start + in->extents[dirext].cooked.ex_bn +
269			(cur - ibase) /
270			(EFS_BLOCKSIZE / sizeof(efs_extent));
271		ioffset = (cur - ibase) %
272			(EFS_BLOCKSIZE / sizeof(efs_extent));
273
274		if (first || lastblock != iblock) {
275			if (bh) brelse(bh);
276
277			bh = sb_bread(inode->i_sb, iblock);
278			if (!bh) {
279				pr_err("%s() failed at block %d\n",
280				       __func__, iblock);
281				return 0;
282			}
283			pr_debug("%s(): read indirect extent block %d\n",
284				 __func__, iblock);
285			first = 0;
286			lastblock = iblock;
287		}
288
289		exts = (efs_extent *) bh->b_data;
290
291		extent_copy(&(exts[ioffset]), &ext);
292
293		if (ext.cooked.ex_magic != 0) {
294			pr_err("extent %d has bad magic number in block %d\n",
295			       cur, iblock);
296			if (bh) brelse(bh);
297			return 0;
298		}
299
300		if ((result = efs_extent_check(&ext, block, sb))) {
301			if (bh) brelse(bh);
302			in->lastextent = cur;
303			return result;
304		}
305	}
306	if (bh) brelse(bh);
307	pr_err("%s() failed to map block %u (indir)\n", __func__, block);
308	return 0;
309}
310
311MODULE_LICENSE("GPL");
312