xref: /linux/fs/efs/super.c (revision da5b2ad1c2f18834cb1ce429e2e5a5cf5cbdf21b) 
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * super.c
4  *
5  * Copyright (c) 1999 Al Smith
6  *
7  * Portions derived from work (c) 1995,1996 Christian Vogelgsang.
8  */
9 
10 #include <linux/init.h>
11 #include <linux/module.h>
12 #include <linux/exportfs.h>
13 #include <linux/slab.h>
14 #include <linux/buffer_head.h>
15 #include <linux/vfs.h>
16 #include <linux/blkdev.h>
17 #include <linux/fs_context.h>
18 #include <linux/fs_parser.h>
19 #include "efs.h"
20 #include <linux/efs_vh.h>
21 #include <linux/efs_fs_sb.h>
22 
23 static int efs_statfs(struct dentry *dentry, struct kstatfs *buf);
24 static int efs_init_fs_context(struct fs_context *fc);
25 
26 static void efs_kill_sb(struct super_block *s)
27 {
28 	struct efs_sb_info *sbi = SUPER_INFO(s);
29 	kill_block_super(s);
30 	kfree(sbi);
31 }
32 
33 static struct pt_types sgi_pt_types[] = {
34 	{0x00,		"SGI vh"},
35 	{0x01,		"SGI trkrepl"},
36 	{0x02,		"SGI secrepl"},
37 	{0x03,		"SGI raw"},
38 	{0x04,		"SGI bsd"},
39 	{SGI_SYSV,	"SGI sysv"},
40 	{0x06,		"SGI vol"},
41 	{SGI_EFS,	"SGI efs"},
42 	{0x08,		"SGI lv"},
43 	{0x09,		"SGI rlv"},
44 	{0x0A,		"SGI xfs"},
45 	{0x0B,		"SGI xfslog"},
46 	{0x0C,		"SGI xlv"},
47 	{0x82,		"Linux swap"},
48 	{0x83,		"Linux native"},
49 	{0,		NULL}
50 };
51 
52 enum {
53 	Opt_explicit_open,
54 };
55 
56 static const struct fs_parameter_spec efs_param_spec[] = {
57 	fsparam_flag    ("explicit-open",       Opt_explicit_open),
58 	{}
59 };
60 
61 /*
62  * File system definition and registration.
63  */
64 static struct file_system_type efs_fs_type = {
65 	.owner			= THIS_MODULE,
66 	.name			= "efs",
67 	.kill_sb		= efs_kill_sb,
68 	.fs_flags		= FS_REQUIRES_DEV,
69 	.init_fs_context	= efs_init_fs_context,
70 	.parameters		= efs_param_spec,
71 };
72 MODULE_ALIAS_FS("efs");
73 
74 static struct kmem_cache * efs_inode_cachep;
75 
76 static struct inode *efs_alloc_inode(struct super_block *sb)
77 {
78 	struct efs_inode_info *ei;
79 	ei = alloc_inode_sb(sb, efs_inode_cachep, GFP_KERNEL);
80 	if (!ei)
81 		return NULL;
82 	return &ei->vfs_inode;
83 }
84 
85 static void efs_free_inode(struct inode *inode)
86 {
87 	kmem_cache_free(efs_inode_cachep, INODE_INFO(inode));
88 }
89 
90 static void init_once(void *foo)
91 {
92 	struct efs_inode_info *ei = (struct efs_inode_info *) foo;
93 
94 	inode_init_once(&ei->vfs_inode);
95 }
96 
97 static int __init init_inodecache(void)
98 {
99 	efs_inode_cachep = kmem_cache_create("efs_inode_cache",
100 				sizeof(struct efs_inode_info), 0,
101 				SLAB_RECLAIM_ACCOUNT|SLAB_ACCOUNT,
102 				init_once);
103 	if (efs_inode_cachep == NULL)
104 		return -ENOMEM;
105 	return 0;
106 }
107 
108 static void destroy_inodecache(void)
109 {
110 	/*
111 	 * Make sure all delayed rcu free inodes are flushed before we
112 	 * destroy cache.
113 	 */
114 	rcu_barrier();
115 	kmem_cache_destroy(efs_inode_cachep);
116 }
117 
118 static const struct super_operations efs_superblock_operations = {
119 	.alloc_inode	= efs_alloc_inode,
120 	.free_inode	= efs_free_inode,
121 	.statfs		= efs_statfs,
122 };
123 
124 static const struct export_operations efs_export_ops = {
125 	.encode_fh	= generic_encode_ino32_fh,
126 	.fh_to_dentry	= efs_fh_to_dentry,
127 	.fh_to_parent	= efs_fh_to_parent,
128 	.get_parent	= efs_get_parent,
129 };
130 
131 static int __init init_efs_fs(void) {
132 	int err;
133 	pr_info(EFS_VERSION" - http://aeschi.ch.eu.org/efs/\n");
134 	err = init_inodecache();
135 	if (err)
136 		goto out1;
137 	err = register_filesystem(&efs_fs_type);
138 	if (err)
139 		goto out;
140 	return 0;
141 out:
142 	destroy_inodecache();
143 out1:
144 	return err;
145 }
146 
147 static void __exit exit_efs_fs(void) {
148 	unregister_filesystem(&efs_fs_type);
149 	destroy_inodecache();
150 }
151 
152 module_init(init_efs_fs)
153 module_exit(exit_efs_fs)
154 
155 static efs_block_t efs_validate_vh(struct volume_header *vh) {
156 	int		i;
157 	__be32		cs, *ui;
158 	int		csum;
159 	efs_block_t	sblock = 0; /* shuts up gcc */
160 	struct pt_types	*pt_entry;
161 	int		pt_type, slice = -1;
162 
163 	if (be32_to_cpu(vh->vh_magic) != VHMAGIC) {
164 		/*
165 		 * assume that we're dealing with a partition and allow
166 		 * read_super() to try and detect a valid superblock
167 		 * on the next block.
168 		 */
169 		return 0;
170 	}
171 
172 	ui = ((__be32 *) (vh + 1)) - 1;
173 	for(csum = 0; ui >= ((__be32 *) vh);) {
174 		cs = *ui--;
175 		csum += be32_to_cpu(cs);
176 	}
177 	if (csum) {
178 		pr_warn("SGI disklabel: checksum bad, label corrupted\n");
179 		return 0;
180 	}
181 
182 #ifdef DEBUG
183 	pr_debug("bf: \"%16s\"\n", vh->vh_bootfile);
184 
185 	for(i = 0; i < NVDIR; i++) {
186 		int	j;
187 		char	name[VDNAMESIZE+1];
188 
189 		for(j = 0; j < VDNAMESIZE; j++) {
190 			name[j] = vh->vh_vd[i].vd_name[j];
191 		}
192 		name[j] = (char) 0;
193 
194 		if (name[0]) {
195 			pr_debug("vh: %8s block: 0x%08x size: 0x%08x\n",
196 				name, (int) be32_to_cpu(vh->vh_vd[i].vd_lbn),
197 				(int) be32_to_cpu(vh->vh_vd[i].vd_nbytes));
198 		}
199 	}
200 #endif
201 
202 	for(i = 0; i < NPARTAB; i++) {
203 		pt_type = (int) be32_to_cpu(vh->vh_pt[i].pt_type);
204 		for(pt_entry = sgi_pt_types; pt_entry->pt_name; pt_entry++) {
205 			if (pt_type == pt_entry->pt_type) break;
206 		}
207 #ifdef DEBUG
208 		if (be32_to_cpu(vh->vh_pt[i].pt_nblks)) {
209 			pr_debug("pt %2d: start: %08d size: %08d type: 0x%02x (%s)\n",
210 				 i, (int)be32_to_cpu(vh->vh_pt[i].pt_firstlbn),
211 				 (int)be32_to_cpu(vh->vh_pt[i].pt_nblks),
212 				 pt_type, (pt_entry->pt_name) ?
213 				 pt_entry->pt_name : "unknown");
214 		}
215 #endif
216 		if (IS_EFS(pt_type)) {
217 			sblock = be32_to_cpu(vh->vh_pt[i].pt_firstlbn);
218 			slice = i;
219 		}
220 	}
221 
222 	if (slice == -1) {
223 		pr_notice("partition table contained no EFS partitions\n");
224 #ifdef DEBUG
225 	} else {
226 		pr_info("using slice %d (type %s, offset 0x%x)\n", slice,
227 			(pt_entry->pt_name) ? pt_entry->pt_name : "unknown",
228 			sblock);
229 #endif
230 	}
231 	return sblock;
232 }
233 
234 static int efs_validate_super(struct efs_sb_info *sb, struct efs_super *super) {
235 
236 	if (!IS_EFS_MAGIC(be32_to_cpu(super->fs_magic)))
237 		return -1;
238 
239 	sb->fs_magic     = be32_to_cpu(super->fs_magic);
240 	sb->total_blocks = be32_to_cpu(super->fs_size);
241 	sb->first_block  = be32_to_cpu(super->fs_firstcg);
242 	sb->group_size   = be32_to_cpu(super->fs_cgfsize);
243 	sb->data_free    = be32_to_cpu(super->fs_tfree);
244 	sb->inode_free   = be32_to_cpu(super->fs_tinode);
245 	sb->inode_blocks = be16_to_cpu(super->fs_cgisize);
246 	sb->total_groups = be16_to_cpu(super->fs_ncg);
247 
248 	return 0;
249 }
250 
251 static int efs_fill_super(struct super_block *s, struct fs_context *fc)
252 {
253 	struct efs_sb_info *sb;
254 	struct buffer_head *bh;
255 	struct inode *root;
256 
257 	sb = kzalloc(sizeof(struct efs_sb_info), GFP_KERNEL);
258 	if (!sb)
259 		return -ENOMEM;
260 	s->s_fs_info = sb;
261 	s->s_time_min = 0;
262 	s->s_time_max = U32_MAX;
263 
264 	s->s_magic		= EFS_SUPER_MAGIC;
265 	if (!sb_set_blocksize(s, EFS_BLOCKSIZE)) {
266 		pr_err("device does not support %d byte blocks\n",
267 			EFS_BLOCKSIZE);
268 		return -EINVAL;
269 	}
270 
271 	/* read the vh (volume header) block */
272 	bh = sb_bread(s, 0);
273 
274 	if (!bh) {
275 		pr_err("cannot read volume header\n");
276 		return -EIO;
277 	}
278 
279 	/*
280 	 * if this returns zero then we didn't find any partition table.
281 	 * this isn't (yet) an error - just assume for the moment that
282 	 * the device is valid and go on to search for a superblock.
283 	 */
284 	sb->fs_start = efs_validate_vh((struct volume_header *) bh->b_data);
285 	brelse(bh);
286 
287 	if (sb->fs_start == -1) {
288 		return -EINVAL;
289 	}
290 
291 	bh = sb_bread(s, sb->fs_start + EFS_SUPER);
292 	if (!bh) {
293 		pr_err("cannot read superblock\n");
294 		return -EIO;
295 	}
296 
297 	if (efs_validate_super(sb, (struct efs_super *) bh->b_data)) {
298 #ifdef DEBUG
299 		pr_warn("invalid superblock at block %u\n",
300 			sb->fs_start + EFS_SUPER);
301 #endif
302 		brelse(bh);
303 		return -EINVAL;
304 	}
305 	brelse(bh);
306 
307 	if (!sb_rdonly(s)) {
308 #ifdef DEBUG
309 		pr_info("forcing read-only mode\n");
310 #endif
311 		s->s_flags |= SB_RDONLY;
312 	}
313 	s->s_op   = &efs_superblock_operations;
314 	s->s_export_op = &efs_export_ops;
315 	root = efs_iget(s, EFS_ROOTINODE);
316 	if (IS_ERR(root)) {
317 		pr_err("get root inode failed\n");
318 		return PTR_ERR(root);
319 	}
320 
321 	s->s_root = d_make_root(root);
322 	if (!(s->s_root)) {
323 		pr_err("get root dentry failed\n");
324 		return -ENOMEM;
325 	}
326 
327 	return 0;
328 }
329 
330 static void efs_free_fc(struct fs_context *fc)
331 {
332 	kfree(fc->fs_private);
333 }
334 
335 static int efs_get_tree(struct fs_context *fc)
336 {
337 	return get_tree_bdev(fc, efs_fill_super);
338 }
339 
340 static int efs_parse_param(struct fs_context *fc, struct fs_parameter *param)
341 {
342 	int token;
343 	struct fs_parse_result result;
344 
345 	token = fs_parse(fc, efs_param_spec, param, &result);
346 	if (token < 0)
347 		return token;
348 	return 0;
349 }
350 
351 static int efs_reconfigure(struct fs_context *fc)
352 {
353 	sync_filesystem(fc->root->d_sb);
354 
355 	return 0;
356 }
357 
358 struct efs_context {
359 	unsigned long s_mount_opts;
360 };
361 
362 static const struct fs_context_operations efs_context_opts = {
363 	.parse_param	= efs_parse_param,
364 	.get_tree	= efs_get_tree,
365 	.reconfigure	= efs_reconfigure,
366 	.free		= efs_free_fc,
367 };
368 
369 /*
370  * Set up the filesystem mount context.
371  */
372 static int efs_init_fs_context(struct fs_context *fc)
373 {
374 	struct efs_context *ctx;
375 
376 	ctx = kzalloc(sizeof(struct efs_context), GFP_KERNEL);
377 	if (!ctx)
378 		return -ENOMEM;
379 	fc->fs_private = ctx;
380 	fc->ops = &efs_context_opts;
381 
382 	return 0;
383 }
384 
385 static int efs_statfs(struct dentry *dentry, struct kstatfs *buf) {
386 	struct super_block *sb = dentry->d_sb;
387 	struct efs_sb_info *sbi = SUPER_INFO(sb);
388 	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
389 
390 	buf->f_type    = EFS_SUPER_MAGIC;	/* efs magic number */
391 	buf->f_bsize   = EFS_BLOCKSIZE;		/* blocksize */
392 	buf->f_blocks  = sbi->total_groups *	/* total data blocks */
393 			(sbi->group_size - sbi->inode_blocks);
394 	buf->f_bfree   = sbi->data_free;	/* free data blocks */
395 	buf->f_bavail  = sbi->data_free;	/* free blocks for non-root */
396 	buf->f_files   = sbi->total_groups *	/* total inodes */
397 			sbi->inode_blocks *
398 			(EFS_BLOCKSIZE / sizeof(struct efs_dinode));
399 	buf->f_ffree   = sbi->inode_free;	/* free inodes */
400 	buf->f_fsid    = u64_to_fsid(id);
401 	buf->f_namelen = EFS_MAXNAMELEN;	/* max filename length */
402 
403 	return 0;
404 }
405 
406