xref: /openbmc/linux/arch/s390/hypfs/inode.c (revision 64c70b1c) 
1 /*
2  *  arch/s390/hypfs/inode.c
3  *    Hypervisor filesystem for Linux on s390.
4  *
5  *    Copyright (C) IBM Corp. 2006
6  *    Author(s): Michael Holzheu <holzheu@de.ibm.com>
7  */
8 
9 #include <linux/types.h>
10 #include <linux/errno.h>
11 #include <linux/fs.h>
12 #include <linux/namei.h>
13 #include <linux/vfs.h>
14 #include <linux/pagemap.h>
15 #include <linux/gfp.h>
16 #include <linux/time.h>
17 #include <linux/parser.h>
18 #include <linux/sysfs.h>
19 #include <linux/module.h>
20 #include <asm/ebcdic.h>
21 #include "hypfs.h"
22 
23 #define HYPFS_MAGIC 0x687970	/* ASCII 'hyp' */
24 #define TMP_SIZE 64		/* size of temporary buffers */
25 
26 static struct dentry *hypfs_create_update_file(struct super_block *sb,
27 					       struct dentry *dir);
28 
29 struct hypfs_sb_info {
30 	uid_t uid;			/* uid used for files and dirs */
31 	gid_t gid;			/* gid used for files and dirs */
32 	struct dentry *update_file;	/* file to trigger update */
33 	time_t last_update;		/* last update time in secs since 1970 */
34 	struct mutex lock;		/* lock to protect update process */
35 };
36 
37 static const struct file_operations hypfs_file_ops;
38 static struct file_system_type hypfs_type;
39 static struct super_operations hypfs_s_ops;
40 
41 /* start of list of all dentries, which have to be deleted on update */
42 static struct dentry *hypfs_last_dentry;
43 
44 static void hypfs_update_update(struct super_block *sb)
45 {
46 	struct hypfs_sb_info *sb_info = sb->s_fs_info;
47 	struct inode *inode = sb_info->update_file->d_inode;
48 
49 	sb_info->last_update = get_seconds();
50 	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
51 }
52 
53 /* directory tree removal functions */
54 
55 static void hypfs_add_dentry(struct dentry *dentry)
56 {
57 	dentry->d_fsdata = hypfs_last_dentry;
58 	hypfs_last_dentry = dentry;
59 }
60 
61 static void hypfs_remove(struct dentry *dentry)
62 {
63 	struct dentry *parent;
64 
65 	parent = dentry->d_parent;
66 	if (S_ISDIR(dentry->d_inode->i_mode))
67 		simple_rmdir(parent->d_inode, dentry);
68 	else
69 		simple_unlink(parent->d_inode, dentry);
70 	d_delete(dentry);
71 	dput(dentry);
72 }
73 
74 static void hypfs_delete_tree(struct dentry *root)
75 {
76 	while (hypfs_last_dentry) {
77 		struct dentry *next_dentry;
78 		next_dentry = hypfs_last_dentry->d_fsdata;
79 		hypfs_remove(hypfs_last_dentry);
80 		hypfs_last_dentry = next_dentry;
81 	}
82 }
83 
84 static struct inode *hypfs_make_inode(struct super_block *sb, int mode)
85 {
86 	struct inode *ret = new_inode(sb);
87 
88 	if (ret) {
89 		struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
90 		ret->i_mode = mode;
91 		ret->i_uid = hypfs_info->uid;
92 		ret->i_gid = hypfs_info->gid;
93 		ret->i_blocks = 0;
94 		ret->i_atime = ret->i_mtime = ret->i_ctime = CURRENT_TIME;
95 		if (mode & S_IFDIR)
96 			ret->i_nlink = 2;
97 		else
98 			ret->i_nlink = 1;
99 	}
100 	return ret;
101 }
102 
103 static void hypfs_drop_inode(struct inode *inode)
104 {
105 	kfree(inode->i_private);
106 	generic_delete_inode(inode);
107 }
108 
109 static int hypfs_open(struct inode *inode, struct file *filp)
110 {
111 	char *data = filp->f_path.dentry->d_inode->i_private;
112 	struct hypfs_sb_info *fs_info;
113 
114 	if (filp->f_mode & FMODE_WRITE) {
115 		if (!(inode->i_mode & S_IWUGO))
116 			return -EACCES;
117 	}
118 	if (filp->f_mode & FMODE_READ) {
119 		if (!(inode->i_mode & S_IRUGO))
120 			return -EACCES;
121 	}
122 
123 	fs_info = inode->i_sb->s_fs_info;
124 	if(data) {
125 		mutex_lock(&fs_info->lock);
126 		filp->private_data = kstrdup(data, GFP_KERNEL);
127 		if (!filp->private_data) {
128 			mutex_unlock(&fs_info->lock);
129 			return -ENOMEM;
130 		}
131 		mutex_unlock(&fs_info->lock);
132 	}
133 	return 0;
134 }
135 
136 static ssize_t hypfs_aio_read(struct kiocb *iocb, const struct iovec *iov,
137 			      unsigned long nr_segs, loff_t offset)
138 {
139 	char *data;
140 	size_t len;
141 	struct file *filp = iocb->ki_filp;
142 	/* XXX: temporary */
143 	char __user *buf = iov[0].iov_base;
144 	size_t count = iov[0].iov_len;
145 
146 	if (nr_segs != 1) {
147 		count = -EINVAL;
148 		goto out;
149 	}
150 
151 	data = filp->private_data;
152 	len = strlen(data);
153 	if (offset > len) {
154 		count = 0;
155 		goto out;
156 	}
157 	if (count > len - offset)
158 		count = len - offset;
159 	if (copy_to_user(buf, data + offset, count)) {
160 		count = -EFAULT;
161 		goto out;
162 	}
163 	iocb->ki_pos += count;
164 	file_accessed(filp);
165 out:
166 	return count;
167 }
168 static ssize_t hypfs_aio_write(struct kiocb *iocb, const struct iovec *iov,
169 			      unsigned long nr_segs, loff_t offset)
170 {
171 	int rc;
172 	struct super_block *sb;
173 	struct hypfs_sb_info *fs_info;
174 	size_t count = iov_length(iov, nr_segs);
175 
176 	sb = iocb->ki_filp->f_path.dentry->d_inode->i_sb;
177 	fs_info = sb->s_fs_info;
178 	/*
179 	 * Currently we only allow one update per second for two reasons:
180 	 * 1. diag 204 is VERY expensive
181 	 * 2. If several processes do updates in parallel and then read the
182 	 *    hypfs data, the likelihood of collisions is reduced, if we restrict
183 	 *    the minimum update interval. A collision occurs, if during the
184 	 *    data gathering of one process another process triggers an update
185 	 *    If the first process wants to ensure consistent data, it has
186 	 *    to restart data collection in this case.
187 	 */
188 	mutex_lock(&fs_info->lock);
189 	if (fs_info->last_update == get_seconds()) {
190 		rc = -EBUSY;
191 		goto out;
192 	}
193 	hypfs_delete_tree(sb->s_root);
194 	if (MACHINE_IS_VM)
195 		rc = hypfs_vm_create_files(sb, sb->s_root);
196 	else
197 		rc = hypfs_diag_create_files(sb, sb->s_root);
198 	if (rc) {
199 		printk(KERN_ERR "hypfs: Update failed\n");
200 		hypfs_delete_tree(sb->s_root);
201 		goto out;
202 	}
203 	hypfs_update_update(sb);
204 	rc = count;
205 out:
206 	mutex_unlock(&fs_info->lock);
207 	return rc;
208 }
209 
210 static int hypfs_release(struct inode *inode, struct file *filp)
211 {
212 	kfree(filp->private_data);
213 	return 0;
214 }
215 
216 enum { opt_uid, opt_gid, opt_err };
217 
218 static match_table_t hypfs_tokens = {
219 	{opt_uid, "uid=%u"},
220 	{opt_gid, "gid=%u"},
221 	{opt_err, NULL}
222 };
223 
224 static int hypfs_parse_options(char *options, struct super_block *sb)
225 {
226 	char *str;
227 	substring_t args[MAX_OPT_ARGS];
228 
229 	if (!options)
230 		return 0;
231 	while ((str = strsep(&options, ",")) != NULL) {
232 		int token, option;
233 		struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
234 
235 		if (!*str)
236 			continue;
237 		token = match_token(str, hypfs_tokens, args);
238 		switch (token) {
239 		case opt_uid:
240 			if (match_int(&args[0], &option))
241 				return -EINVAL;
242 			hypfs_info->uid = option;
243 			break;
244 		case opt_gid:
245 			if (match_int(&args[0], &option))
246 				return -EINVAL;
247 			hypfs_info->gid = option;
248 			break;
249 		case opt_err:
250 		default:
251 			printk(KERN_ERR "hypfs: Unrecognized mount option "
252 			       "\"%s\" or missing value\n", str);
253 			return -EINVAL;
254 		}
255 	}
256 	return 0;
257 }
258 
259 static int hypfs_fill_super(struct super_block *sb, void *data, int silent)
260 {
261 	struct inode *root_inode;
262 	struct dentry *root_dentry;
263 	int rc = 0;
264 	struct hypfs_sb_info *sbi;
265 
266 	sbi = kzalloc(sizeof(struct hypfs_sb_info), GFP_KERNEL);
267 	if (!sbi)
268 		return -ENOMEM;
269 	mutex_init(&sbi->lock);
270 	sbi->uid = current->uid;
271 	sbi->gid = current->gid;
272 	sb->s_fs_info = sbi;
273 	sb->s_blocksize = PAGE_CACHE_SIZE;
274 	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
275 	sb->s_magic = HYPFS_MAGIC;
276 	sb->s_op = &hypfs_s_ops;
277 	if (hypfs_parse_options(data, sb)) {
278 		rc = -EINVAL;
279 		goto err_alloc;
280 	}
281 	root_inode = hypfs_make_inode(sb, S_IFDIR | 0755);
282 	if (!root_inode) {
283 		rc = -ENOMEM;
284 		goto err_alloc;
285 	}
286 	root_inode->i_op = &simple_dir_inode_operations;
287 	root_inode->i_fop = &simple_dir_operations;
288 	root_dentry = d_alloc_root(root_inode);
289 	if (!root_dentry) {
290 		iput(root_inode);
291 		rc = -ENOMEM;
292 		goto err_alloc;
293 	}
294 	if (MACHINE_IS_VM)
295 		rc = hypfs_vm_create_files(sb, root_dentry);
296 	else
297 		rc = hypfs_diag_create_files(sb, root_dentry);
298 	if (rc)
299 		goto err_tree;
300 	sbi->update_file = hypfs_create_update_file(sb, root_dentry);
301 	if (IS_ERR(sbi->update_file)) {
302 		rc = PTR_ERR(sbi->update_file);
303 		goto err_tree;
304 	}
305 	hypfs_update_update(sb);
306 	sb->s_root = root_dentry;
307 	return 0;
308 
309 err_tree:
310 	hypfs_delete_tree(root_dentry);
311 	d_genocide(root_dentry);
312 	dput(root_dentry);
313 err_alloc:
314 	kfree(sbi);
315 	return rc;
316 }
317 
318 static int hypfs_get_super(struct file_system_type *fst, int flags,
319 			const char *devname, void *data, struct vfsmount *mnt)
320 {
321 	return get_sb_single(fst, flags, data, hypfs_fill_super, mnt);
322 }
323 
324 static void hypfs_kill_super(struct super_block *sb)
325 {
326 	struct hypfs_sb_info *sb_info = sb->s_fs_info;
327 
328 	if (sb->s_root) {
329 		hypfs_delete_tree(sb->s_root);
330 		hypfs_remove(sb_info->update_file);
331 		kfree(sb->s_fs_info);
332 		sb->s_fs_info = NULL;
333 	}
334 	kill_litter_super(sb);
335 }
336 
337 static struct dentry *hypfs_create_file(struct super_block *sb,
338 					struct dentry *parent, const char *name,
339 					char *data, mode_t mode)
340 {
341 	struct dentry *dentry;
342 	struct inode *inode;
343 	struct qstr qname;
344 
345 	qname.name = name;
346 	qname.len = strlen(name);
347 	qname.hash = full_name_hash(name, qname.len);
348 	dentry = lookup_one_len(name, parent, strlen(name));
349 	if (IS_ERR(dentry))
350 		return ERR_PTR(-ENOMEM);
351 	inode = hypfs_make_inode(sb, mode);
352 	if (!inode) {
353 		dput(dentry);
354 		return ERR_PTR(-ENOMEM);
355 	}
356 	if (mode & S_IFREG) {
357 		inode->i_fop = &hypfs_file_ops;
358 		if (data)
359 			inode->i_size = strlen(data);
360 		else
361 			inode->i_size = 0;
362 	} else if (mode & S_IFDIR) {
363 		inode->i_op = &simple_dir_inode_operations;
364 		inode->i_fop = &simple_dir_operations;
365 		parent->d_inode->i_nlink++;
366 	} else
367 		BUG();
368 	inode->i_private = data;
369 	d_instantiate(dentry, inode);
370 	dget(dentry);
371 	return dentry;
372 }
373 
374 struct dentry *hypfs_mkdir(struct super_block *sb, struct dentry *parent,
375 			   const char *name)
376 {
377 	struct dentry *dentry;
378 
379 	dentry = hypfs_create_file(sb, parent, name, NULL, S_IFDIR | DIR_MODE);
380 	if (IS_ERR(dentry))
381 		return dentry;
382 	hypfs_add_dentry(dentry);
383 	parent->d_inode->i_nlink++;
384 	return dentry;
385 }
386 
387 static struct dentry *hypfs_create_update_file(struct super_block *sb,
388 					       struct dentry *dir)
389 {
390 	struct dentry *dentry;
391 
392 	dentry = hypfs_create_file(sb, dir, "update", NULL,
393 				   S_IFREG | UPDATE_FILE_MODE);
394 	/*
395 	 * We do not put the update file on the 'delete' list with
396 	 * hypfs_add_dentry(), since it should not be removed when the tree
397 	 * is updated.
398 	 */
399 	return dentry;
400 }
401 
402 struct dentry *hypfs_create_u64(struct super_block *sb, struct dentry *dir,
403 				const char *name, __u64 value)
404 {
405 	char *buffer;
406 	char tmp[TMP_SIZE];
407 	struct dentry *dentry;
408 
409 	snprintf(tmp, TMP_SIZE, "%lld\n", (unsigned long long int)value);
410 	buffer = kstrdup(tmp, GFP_KERNEL);
411 	if (!buffer)
412 		return ERR_PTR(-ENOMEM);
413 	dentry =
414 	    hypfs_create_file(sb, dir, name, buffer, S_IFREG | REG_FILE_MODE);
415 	if (IS_ERR(dentry)) {
416 		kfree(buffer);
417 		return ERR_PTR(-ENOMEM);
418 	}
419 	hypfs_add_dentry(dentry);
420 	return dentry;
421 }
422 
423 struct dentry *hypfs_create_str(struct super_block *sb, struct dentry *dir,
424 				const char *name, char *string)
425 {
426 	char *buffer;
427 	struct dentry *dentry;
428 
429 	buffer = kmalloc(strlen(string) + 2, GFP_KERNEL);
430 	if (!buffer)
431 		return ERR_PTR(-ENOMEM);
432 	sprintf(buffer, "%s\n", string);
433 	dentry =
434 	    hypfs_create_file(sb, dir, name, buffer, S_IFREG | REG_FILE_MODE);
435 	if (IS_ERR(dentry)) {
436 		kfree(buffer);
437 		return ERR_PTR(-ENOMEM);
438 	}
439 	hypfs_add_dentry(dentry);
440 	return dentry;
441 }
442 
443 static const struct file_operations hypfs_file_ops = {
444 	.open		= hypfs_open,
445 	.release	= hypfs_release,
446 	.read		= do_sync_read,
447 	.write		= do_sync_write,
448 	.aio_read	= hypfs_aio_read,
449 	.aio_write	= hypfs_aio_write,
450 };
451 
452 static struct file_system_type hypfs_type = {
453 	.owner		= THIS_MODULE,
454 	.name		= "s390_hypfs",
455 	.get_sb		= hypfs_get_super,
456 	.kill_sb	= hypfs_kill_super
457 };
458 
459 static struct super_operations hypfs_s_ops = {
460 	.statfs		= simple_statfs,
461 	.drop_inode	= hypfs_drop_inode,
462 };
463 
464 static decl_subsys(s390, NULL, NULL);
465 
466 static int __init hypfs_init(void)
467 {
468 	int rc;
469 
470 	if (MACHINE_IS_VM) {
471 		if (hypfs_vm_init())
472 			/* no diag 2fc, just exit */
473 			return -ENODATA;
474 	} else {
475 		if (hypfs_diag_init()) {
476 			rc = -ENODATA;
477 			goto fail_diag;
478 		}
479 	}
480 	kobj_set_kset_s(&s390_subsys, hypervisor_subsys);
481 	rc = subsystem_register(&s390_subsys);
482 	if (rc)
483 		goto fail_sysfs;
484 	rc = register_filesystem(&hypfs_type);
485 	if (rc)
486 		goto fail_filesystem;
487 	return 0;
488 
489 fail_filesystem:
490 	subsystem_unregister(&s390_subsys);
491 fail_sysfs:
492 	if (!MACHINE_IS_VM)
493 		hypfs_diag_exit();
494 fail_diag:
495 	printk(KERN_ERR "hypfs: Initialization failed with rc = %i.\n", rc);
496 	return rc;
497 }
498 
499 static void __exit hypfs_exit(void)
500 {
501 	if (!MACHINE_IS_VM)
502 		hypfs_diag_exit();
503 	unregister_filesystem(&hypfs_type);
504 	subsystem_unregister(&s390_subsys);
505 }
506 
507 module_init(hypfs_init)
508 module_exit(hypfs_exit)
509 
510 MODULE_LICENSE("GPL");
511 MODULE_AUTHOR("Michael Holzheu <holzheu@de.ibm.com>");
512 MODULE_DESCRIPTION("s390 Hypervisor Filesystem");
513