xref: /linux/fs/efs/super.c (revision d642ef71) 
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 
18 #include "efs.h"
19 #include <linux/efs_vh.h>
20 #include <linux/efs_fs_sb.h>
21 
22 static int efs_statfs(struct dentry *dentry, struct kstatfs *buf);
23 static int efs_fill_super(struct super_block *s, void *d, int silent);
24 
25 static struct dentry *efs_mount(struct file_system_type *fs_type,
26 	int flags, const char *dev_name, void *data)
27 {
28 	return mount_bdev(fs_type, flags, dev_name, data, efs_fill_super);
29 }
30 
31 static void efs_kill_sb(struct super_block *s)
32 {
33 	struct efs_sb_info *sbi = SUPER_INFO(s);
34 	kill_block_super(s);
35 	kfree(sbi);
36 }
37 
38 static struct file_system_type efs_fs_type = {
39 	.owner		= THIS_MODULE,
40 	.name		= "efs",
41 	.mount		= efs_mount,
42 	.kill_sb	= efs_kill_sb,
43 	.fs_flags	= FS_REQUIRES_DEV,
44 };
45 MODULE_ALIAS_FS("efs");
46 
47 static struct pt_types sgi_pt_types[] = {
48 	{0x00,		"SGI vh"},
49 	{0x01,		"SGI trkrepl"},
50 	{0x02,		"SGI secrepl"},
51 	{0x03,		"SGI raw"},
52 	{0x04,		"SGI bsd"},
53 	{SGI_SYSV,	"SGI sysv"},
54 	{0x06,		"SGI vol"},
55 	{SGI_EFS,	"SGI efs"},
56 	{0x08,		"SGI lv"},
57 	{0x09,		"SGI rlv"},
58 	{0x0A,		"SGI xfs"},
59 	{0x0B,		"SGI xfslog"},
60 	{0x0C,		"SGI xlv"},
61 	{0x82,		"Linux swap"},
62 	{0x83,		"Linux native"},
63 	{0,		NULL}
64 };
65 
66 
67 static struct kmem_cache * efs_inode_cachep;
68 
69 static struct inode *efs_alloc_inode(struct super_block *sb)
70 {
71 	struct efs_inode_info *ei;
72 	ei = alloc_inode_sb(sb, efs_inode_cachep, GFP_KERNEL);
73 	if (!ei)
74 		return NULL;
75 	return &ei->vfs_inode;
76 }
77 
78 static void efs_free_inode(struct inode *inode)
79 {
80 	kmem_cache_free(efs_inode_cachep, INODE_INFO(inode));
81 }
82 
83 static void init_once(void *foo)
84 {
85 	struct efs_inode_info *ei = (struct efs_inode_info *) foo;
86 
87 	inode_init_once(&ei->vfs_inode);
88 }
89 
90 static int __init init_inodecache(void)
91 {
92 	efs_inode_cachep = kmem_cache_create("efs_inode_cache",
93 				sizeof(struct efs_inode_info), 0,
94 				SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD|
95 				SLAB_ACCOUNT, init_once);
96 	if (efs_inode_cachep == NULL)
97 		return -ENOMEM;
98 	return 0;
99 }
100 
101 static void destroy_inodecache(void)
102 {
103 	/*
104 	 * Make sure all delayed rcu free inodes are flushed before we
105 	 * destroy cache.
106 	 */
107 	rcu_barrier();
108 	kmem_cache_destroy(efs_inode_cachep);
109 }
110 
111 static int efs_remount(struct super_block *sb, int *flags, char *data)
112 {
113 	sync_filesystem(sb);
114 	*flags |= SB_RDONLY;
115 	return 0;
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 	.remount_fs	= efs_remount,
123 };
124 
125 static const struct export_operations efs_export_ops = {
126 	.encode_fh	= generic_encode_ino32_fh,
127 	.fh_to_dentry	= efs_fh_to_dentry,
128 	.fh_to_parent	= efs_fh_to_parent,
129 	.get_parent	= efs_get_parent,
130 };
131 
132 static int __init init_efs_fs(void) {
133 	int err;
134 	pr_info(EFS_VERSION" - http://aeschi.ch.eu.org/efs/\n");
135 	err = init_inodecache();
136 	if (err)
137 		goto out1;
138 	err = register_filesystem(&efs_fs_type);
139 	if (err)
140 		goto out;
141 	return 0;
142 out:
143 	destroy_inodecache();
144 out1:
145 	return err;
146 }
147 
148 static void __exit exit_efs_fs(void) {
149 	unregister_filesystem(&efs_fs_type);
150 	destroy_inodecache();
151 }
152 
153 module_init(init_efs_fs)
154 module_exit(exit_efs_fs)
155 
156 static efs_block_t efs_validate_vh(struct volume_header *vh) {
157 	int		i;
158 	__be32		cs, *ui;
159 	int		csum;
160 	efs_block_t	sblock = 0; /* shuts up gcc */
161 	struct pt_types	*pt_entry;
162 	int		pt_type, slice = -1;
163 
164 	if (be32_to_cpu(vh->vh_magic) != VHMAGIC) {
165 		/*
166 		 * assume that we're dealing with a partition and allow
167 		 * read_super() to try and detect a valid superblock
168 		 * on the next block.
169 		 */
170 		return 0;
171 	}
172 
173 	ui = ((__be32 *) (vh + 1)) - 1;
174 	for(csum = 0; ui >= ((__be32 *) vh);) {
175 		cs = *ui--;
176 		csum += be32_to_cpu(cs);
177 	}
178 	if (csum) {
179 		pr_warn("SGI disklabel: checksum bad, label corrupted\n");
180 		return 0;
181 	}
182 
183 #ifdef DEBUG
184 	pr_debug("bf: \"%16s\"\n", vh->vh_bootfile);
185 
186 	for(i = 0; i < NVDIR; i++) {
187 		int	j;
188 		char	name[VDNAMESIZE+1];
189 
190 		for(j = 0; j < VDNAMESIZE; j++) {
191 			name[j] = vh->vh_vd[i].vd_name[j];
192 		}
193 		name[j] = (char) 0;
194 
195 		if (name[0]) {
196 			pr_debug("vh: %8s block: 0x%08x size: 0x%08x\n",
197 				name, (int) be32_to_cpu(vh->vh_vd[i].vd_lbn),
198 				(int) be32_to_cpu(vh->vh_vd[i].vd_nbytes));
199 		}
200 	}
201 #endif
202 
203 	for(i = 0; i < NPARTAB; i++) {
204 		pt_type = (int) be32_to_cpu(vh->vh_pt[i].pt_type);
205 		for(pt_entry = sgi_pt_types; pt_entry->pt_name; pt_entry++) {
206 			if (pt_type == pt_entry->pt_type) break;
207 		}
208 #ifdef DEBUG
209 		if (be32_to_cpu(vh->vh_pt[i].pt_nblks)) {
210 			pr_debug("pt %2d: start: %08d size: %08d type: 0x%02x (%s)\n",
211 				 i, (int)be32_to_cpu(vh->vh_pt[i].pt_firstlbn),
212 				 (int)be32_to_cpu(vh->vh_pt[i].pt_nblks),
213 				 pt_type, (pt_entry->pt_name) ?
214 				 pt_entry->pt_name : "unknown");
215 		}
216 #endif
217 		if (IS_EFS(pt_type)) {
218 			sblock = be32_to_cpu(vh->vh_pt[i].pt_firstlbn);
219 			slice = i;
220 		}
221 	}
222 
223 	if (slice == -1) {
224 		pr_notice("partition table contained no EFS partitions\n");
225 #ifdef DEBUG
226 	} else {
227 		pr_info("using slice %d (type %s, offset 0x%x)\n", slice,
228 			(pt_entry->pt_name) ? pt_entry->pt_name : "unknown",
229 			sblock);
230 #endif
231 	}
232 	return sblock;
233 }
234 
235 static int efs_validate_super(struct efs_sb_info *sb, struct efs_super *super) {
236 
237 	if (!IS_EFS_MAGIC(be32_to_cpu(super->fs_magic)))
238 		return -1;
239 
240 	sb->fs_magic     = be32_to_cpu(super->fs_magic);
241 	sb->total_blocks = be32_to_cpu(super->fs_size);
242 	sb->first_block  = be32_to_cpu(super->fs_firstcg);
243 	sb->group_size   = be32_to_cpu(super->fs_cgfsize);
244 	sb->data_free    = be32_to_cpu(super->fs_tfree);
245 	sb->inode_free   = be32_to_cpu(super->fs_tinode);
246 	sb->inode_blocks = be16_to_cpu(super->fs_cgisize);
247 	sb->total_groups = be16_to_cpu(super->fs_ncg);
248 
249 	return 0;
250 }
251 
252 static int efs_fill_super(struct super_block *s, void *d, int silent)
253 {
254 	struct efs_sb_info *sb;
255 	struct buffer_head *bh;
256 	struct inode *root;
257 
258  	sb = kzalloc(sizeof(struct efs_sb_info), GFP_KERNEL);
259 	if (!sb)
260 		return -ENOMEM;
261 	s->s_fs_info = sb;
262 	s->s_time_min = 0;
263 	s->s_time_max = U32_MAX;
264 
265 	s->s_magic		= EFS_SUPER_MAGIC;
266 	if (!sb_set_blocksize(s, EFS_BLOCKSIZE)) {
267 		pr_err("device does not support %d byte blocks\n",
268 			EFS_BLOCKSIZE);
269 		return -EINVAL;
270 	}
271 
272 	/* read the vh (volume header) block */
273 	bh = sb_bread(s, 0);
274 
275 	if (!bh) {
276 		pr_err("cannot read volume header\n");
277 		return -EIO;
278 	}
279 
280 	/*
281 	 * if this returns zero then we didn't find any partition table.
282 	 * this isn't (yet) an error - just assume for the moment that
283 	 * the device is valid and go on to search for a superblock.
284 	 */
285 	sb->fs_start = efs_validate_vh((struct volume_header *) bh->b_data);
286 	brelse(bh);
287 
288 	if (sb->fs_start == -1) {
289 		return -EINVAL;
290 	}
291 
292 	bh = sb_bread(s, sb->fs_start + EFS_SUPER);
293 	if (!bh) {
294 		pr_err("cannot read superblock\n");
295 		return -EIO;
296 	}
297 
298 	if (efs_validate_super(sb, (struct efs_super *) bh->b_data)) {
299 #ifdef DEBUG
300 		pr_warn("invalid superblock at block %u\n",
301 			sb->fs_start + EFS_SUPER);
302 #endif
303 		brelse(bh);
304 		return -EINVAL;
305 	}
306 	brelse(bh);
307 
308 	if (!sb_rdonly(s)) {
309 #ifdef DEBUG
310 		pr_info("forcing read-only mode\n");
311 #endif
312 		s->s_flags |= SB_RDONLY;
313 	}
314 	s->s_op   = &efs_superblock_operations;
315 	s->s_export_op = &efs_export_ops;
316 	root = efs_iget(s, EFS_ROOTINODE);
317 	if (IS_ERR(root)) {
318 		pr_err("get root inode failed\n");
319 		return PTR_ERR(root);
320 	}
321 
322 	s->s_root = d_make_root(root);
323 	if (!(s->s_root)) {
324 		pr_err("get root dentry failed\n");
325 		return -ENOMEM;
326 	}
327 
328 	return 0;
329 }
330 
331 static int efs_statfs(struct dentry *dentry, struct kstatfs *buf) {
332 	struct super_block *sb = dentry->d_sb;
333 	struct efs_sb_info *sbi = SUPER_INFO(sb);
334 	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
335 
336 	buf->f_type    = EFS_SUPER_MAGIC;	/* efs magic number */
337 	buf->f_bsize   = EFS_BLOCKSIZE;		/* blocksize */
338 	buf->f_blocks  = sbi->total_groups *	/* total data blocks */
339 			(sbi->group_size - sbi->inode_blocks);
340 	buf->f_bfree   = sbi->data_free;	/* free data blocks */
341 	buf->f_bavail  = sbi->data_free;	/* free blocks for non-root */
342 	buf->f_files   = sbi->total_groups *	/* total inodes */
343 			sbi->inode_blocks *
344 			(EFS_BLOCKSIZE / sizeof(struct efs_dinode));
345 	buf->f_ffree   = sbi->inode_free;	/* free inodes */
346 	buf->f_fsid    = u64_to_fsid(id);
347 	buf->f_namelen = EFS_MAXNAMELEN;	/* max filename length */
348 
349 	return 0;
350 }
351 
352