xref: /openbmc/linux/arch/s390/hypfs/inode.c (revision 4800cd83) 
1 /*
2  *  arch/s390/hypfs/inode.c
3  *    Hypervisor filesystem for Linux on s390.
4  *
5  *    Copyright IBM Corp. 2006, 2008
6  *    Author(s): Michael Holzheu <holzheu@de.ibm.com>
7  */
8 
9 #define KMSG_COMPONENT "hypfs"
10 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
11 
12 #include <linux/types.h>
13 #include <linux/errno.h>
14 #include <linux/fs.h>
15 #include <linux/namei.h>
16 #include <linux/vfs.h>
17 #include <linux/slab.h>
18 #include <linux/pagemap.h>
19 #include <linux/time.h>
20 #include <linux/parser.h>
21 #include <linux/sysfs.h>
22 #include <linux/module.h>
23 #include <linux/seq_file.h>
24 #include <linux/mount.h>
25 #include <asm/ebcdic.h>
26 #include "hypfs.h"
27 
28 #define HYPFS_MAGIC 0x687970	/* ASCII 'hyp' */
29 #define TMP_SIZE 64		/* size of temporary buffers */
30 
31 static struct dentry *hypfs_create_update_file(struct super_block *sb,
32 					       struct dentry *dir);
33 
34 struct hypfs_sb_info {
35 	uid_t uid;			/* uid used for files and dirs */
36 	gid_t gid;			/* gid used for files and dirs */
37 	struct dentry *update_file;	/* file to trigger update */
38 	time_t last_update;		/* last update time in secs since 1970 */
39 	struct mutex lock;		/* lock to protect update process */
40 };
41 
42 static const struct file_operations hypfs_file_ops;
43 static struct file_system_type hypfs_type;
44 static const struct super_operations hypfs_s_ops;
45 
46 /* start of list of all dentries, which have to be deleted on update */
47 static struct dentry *hypfs_last_dentry;
48 
49 static void hypfs_update_update(struct super_block *sb)
50 {
51 	struct hypfs_sb_info *sb_info = sb->s_fs_info;
52 	struct inode *inode = sb_info->update_file->d_inode;
53 
54 	sb_info->last_update = get_seconds();
55 	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
56 }
57 
58 /* directory tree removal functions */
59 
60 static void hypfs_add_dentry(struct dentry *dentry)
61 {
62 	dentry->d_fsdata = hypfs_last_dentry;
63 	hypfs_last_dentry = dentry;
64 }
65 
66 static inline int hypfs_positive(struct dentry *dentry)
67 {
68 	return dentry->d_inode && !d_unhashed(dentry);
69 }
70 
71 static void hypfs_remove(struct dentry *dentry)
72 {
73 	struct dentry *parent;
74 
75 	parent = dentry->d_parent;
76 	if (!parent || !parent->d_inode)
77 		return;
78 	mutex_lock(&parent->d_inode->i_mutex);
79 	if (hypfs_positive(dentry)) {
80 		if (S_ISDIR(dentry->d_inode->i_mode))
81 			simple_rmdir(parent->d_inode, dentry);
82 		else
83 			simple_unlink(parent->d_inode, dentry);
84 	}
85 	d_delete(dentry);
86 	dput(dentry);
87 	mutex_unlock(&parent->d_inode->i_mutex);
88 }
89 
90 static void hypfs_delete_tree(struct dentry *root)
91 {
92 	while (hypfs_last_dentry) {
93 		struct dentry *next_dentry;
94 		next_dentry = hypfs_last_dentry->d_fsdata;
95 		hypfs_remove(hypfs_last_dentry);
96 		hypfs_last_dentry = next_dentry;
97 	}
98 }
99 
100 static struct inode *hypfs_make_inode(struct super_block *sb, int mode)
101 {
102 	struct inode *ret = new_inode(sb);
103 
104 	if (ret) {
105 		struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
106 		ret->i_mode = mode;
107 		ret->i_uid = hypfs_info->uid;
108 		ret->i_gid = hypfs_info->gid;
109 		ret->i_atime = ret->i_mtime = ret->i_ctime = CURRENT_TIME;
110 		if (mode & S_IFDIR)
111 			ret->i_nlink = 2;
112 		else
113 			ret->i_nlink = 1;
114 	}
115 	return ret;
116 }
117 
118 static void hypfs_evict_inode(struct inode *inode)
119 {
120 	end_writeback(inode);
121 	kfree(inode->i_private);
122 }
123 
124 static int hypfs_open(struct inode *inode, struct file *filp)
125 {
126 	char *data = filp->f_path.dentry->d_inode->i_private;
127 	struct hypfs_sb_info *fs_info;
128 
129 	if (filp->f_mode & FMODE_WRITE) {
130 		if (!(inode->i_mode & S_IWUGO))
131 			return -EACCES;
132 	}
133 	if (filp->f_mode & FMODE_READ) {
134 		if (!(inode->i_mode & S_IRUGO))
135 			return -EACCES;
136 	}
137 
138 	fs_info = inode->i_sb->s_fs_info;
139 	if(data) {
140 		mutex_lock(&fs_info->lock);
141 		filp->private_data = kstrdup(data, GFP_KERNEL);
142 		if (!filp->private_data) {
143 			mutex_unlock(&fs_info->lock);
144 			return -ENOMEM;
145 		}
146 		mutex_unlock(&fs_info->lock);
147 	}
148 	return nonseekable_open(inode, filp);
149 }
150 
151 static ssize_t hypfs_aio_read(struct kiocb *iocb, const struct iovec *iov,
152 			      unsigned long nr_segs, loff_t offset)
153 {
154 	char *data;
155 	ssize_t ret;
156 	struct file *filp = iocb->ki_filp;
157 	/* XXX: temporary */
158 	char __user *buf = iov[0].iov_base;
159 	size_t count = iov[0].iov_len;
160 
161 	if (nr_segs != 1)
162 		return -EINVAL;
163 
164 	data = filp->private_data;
165 	ret = simple_read_from_buffer(buf, count, &offset, data, strlen(data));
166 	if (ret <= 0)
167 		return ret;
168 
169 	iocb->ki_pos += ret;
170 	file_accessed(filp);
171 
172 	return ret;
173 }
174 static ssize_t hypfs_aio_write(struct kiocb *iocb, const struct iovec *iov,
175 			      unsigned long nr_segs, loff_t offset)
176 {
177 	int rc;
178 	struct super_block *sb;
179 	struct hypfs_sb_info *fs_info;
180 	size_t count = iov_length(iov, nr_segs);
181 
182 	sb = iocb->ki_filp->f_path.dentry->d_inode->i_sb;
183 	fs_info = sb->s_fs_info;
184 	/*
185 	 * Currently we only allow one update per second for two reasons:
186 	 * 1. diag 204 is VERY expensive
187 	 * 2. If several processes do updates in parallel and then read the
188 	 *    hypfs data, the likelihood of collisions is reduced, if we restrict
189 	 *    the minimum update interval. A collision occurs, if during the
190 	 *    data gathering of one process another process triggers an update
191 	 *    If the first process wants to ensure consistent data, it has
192 	 *    to restart data collection in this case.
193 	 */
194 	mutex_lock(&fs_info->lock);
195 	if (fs_info->last_update == get_seconds()) {
196 		rc = -EBUSY;
197 		goto out;
198 	}
199 	hypfs_delete_tree(sb->s_root);
200 	if (MACHINE_IS_VM)
201 		rc = hypfs_vm_create_files(sb, sb->s_root);
202 	else
203 		rc = hypfs_diag_create_files(sb, sb->s_root);
204 	if (rc) {
205 		pr_err("Updating the hypfs tree failed\n");
206 		hypfs_delete_tree(sb->s_root);
207 		goto out;
208 	}
209 	hypfs_update_update(sb);
210 	rc = count;
211 out:
212 	mutex_unlock(&fs_info->lock);
213 	return rc;
214 }
215 
216 static int hypfs_release(struct inode *inode, struct file *filp)
217 {
218 	kfree(filp->private_data);
219 	return 0;
220 }
221 
222 enum { opt_uid, opt_gid, opt_err };
223 
224 static const match_table_t hypfs_tokens = {
225 	{opt_uid, "uid=%u"},
226 	{opt_gid, "gid=%u"},
227 	{opt_err, NULL}
228 };
229 
230 static int hypfs_parse_options(char *options, struct super_block *sb)
231 {
232 	char *str;
233 	substring_t args[MAX_OPT_ARGS];
234 
235 	if (!options)
236 		return 0;
237 	while ((str = strsep(&options, ",")) != NULL) {
238 		int token, option;
239 		struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
240 
241 		if (!*str)
242 			continue;
243 		token = match_token(str, hypfs_tokens, args);
244 		switch (token) {
245 		case opt_uid:
246 			if (match_int(&args[0], &option))
247 				return -EINVAL;
248 			hypfs_info->uid = option;
249 			break;
250 		case opt_gid:
251 			if (match_int(&args[0], &option))
252 				return -EINVAL;
253 			hypfs_info->gid = option;
254 			break;
255 		case opt_err:
256 		default:
257 			pr_err("%s is not a valid mount option\n", str);
258 			return -EINVAL;
259 		}
260 	}
261 	return 0;
262 }
263 
264 static int hypfs_show_options(struct seq_file *s, struct vfsmount *mnt)
265 {
266 	struct hypfs_sb_info *hypfs_info = mnt->mnt_sb->s_fs_info;
267 
268 	seq_printf(s, ",uid=%u", hypfs_info->uid);
269 	seq_printf(s, ",gid=%u", hypfs_info->gid);
270 	return 0;
271 }
272 
273 static int hypfs_fill_super(struct super_block *sb, void *data, int silent)
274 {
275 	struct inode *root_inode;
276 	struct dentry *root_dentry;
277 	int rc = 0;
278 	struct hypfs_sb_info *sbi;
279 
280 	sbi = kzalloc(sizeof(struct hypfs_sb_info), GFP_KERNEL);
281 	if (!sbi)
282 		return -ENOMEM;
283 	mutex_init(&sbi->lock);
284 	sbi->uid = current_uid();
285 	sbi->gid = current_gid();
286 	sb->s_fs_info = sbi;
287 	sb->s_blocksize = PAGE_CACHE_SIZE;
288 	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
289 	sb->s_magic = HYPFS_MAGIC;
290 	sb->s_op = &hypfs_s_ops;
291 	if (hypfs_parse_options(data, sb))
292 		return -EINVAL;
293 	root_inode = hypfs_make_inode(sb, S_IFDIR | 0755);
294 	if (!root_inode)
295 		return -ENOMEM;
296 	root_inode->i_op = &simple_dir_inode_operations;
297 	root_inode->i_fop = &simple_dir_operations;
298 	sb->s_root = root_dentry = d_alloc_root(root_inode);
299 	if (!root_dentry) {
300 		iput(root_inode);
301 		return -ENOMEM;
302 	}
303 	if (MACHINE_IS_VM)
304 		rc = hypfs_vm_create_files(sb, root_dentry);
305 	else
306 		rc = hypfs_diag_create_files(sb, root_dentry);
307 	if (rc)
308 		return rc;
309 	sbi->update_file = hypfs_create_update_file(sb, root_dentry);
310 	if (IS_ERR(sbi->update_file))
311 		return PTR_ERR(sbi->update_file);
312 	hypfs_update_update(sb);
313 	pr_info("Hypervisor filesystem mounted\n");
314 	return 0;
315 }
316 
317 static struct dentry *hypfs_mount(struct file_system_type *fst, int flags,
318 			const char *devname, void *data)
319 {
320 	return mount_single(fst, flags, data, hypfs_fill_super);
321 }
322 
323 static void hypfs_kill_super(struct super_block *sb)
324 {
325 	struct hypfs_sb_info *sb_info = sb->s_fs_info;
326 
327 	if (sb->s_root)
328 		hypfs_delete_tree(sb->s_root);
329 	if (sb_info->update_file)
330 		hypfs_remove(sb_info->update_file);
331 	kfree(sb->s_fs_info);
332 	sb->s_fs_info = NULL;
333 	kill_litter_super(sb);
334 }
335 
336 static struct dentry *hypfs_create_file(struct super_block *sb,
337 					struct dentry *parent, const char *name,
338 					char *data, mode_t mode)
339 {
340 	struct dentry *dentry;
341 	struct inode *inode;
342 
343 	mutex_lock(&parent->d_inode->i_mutex);
344 	dentry = lookup_one_len(name, parent, strlen(name));
345 	if (IS_ERR(dentry)) {
346 		dentry = ERR_PTR(-ENOMEM);
347 		goto fail;
348 	}
349 	inode = hypfs_make_inode(sb, mode);
350 	if (!inode) {
351 		dput(dentry);
352 		dentry = ERR_PTR(-ENOMEM);
353 		goto fail;
354 	}
355 	if (mode & S_IFREG) {
356 		inode->i_fop = &hypfs_file_ops;
357 		if (data)
358 			inode->i_size = strlen(data);
359 		else
360 			inode->i_size = 0;
361 	} else if (mode & S_IFDIR) {
362 		inode->i_op = &simple_dir_inode_operations;
363 		inode->i_fop = &simple_dir_operations;
364 		parent->d_inode->i_nlink++;
365 	} else
366 		BUG();
367 	inode->i_private = data;
368 	d_instantiate(dentry, inode);
369 	dget(dentry);
370 fail:
371 	mutex_unlock(&parent->d_inode->i_mutex);
372 	return dentry;
373 }
374 
375 struct dentry *hypfs_mkdir(struct super_block *sb, struct dentry *parent,
376 			   const char *name)
377 {
378 	struct dentry *dentry;
379 
380 	dentry = hypfs_create_file(sb, parent, name, NULL, S_IFDIR | DIR_MODE);
381 	if (IS_ERR(dentry))
382 		return dentry;
383 	hypfs_add_dentry(dentry);
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, "%llu\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 	.llseek		= no_llseek,
451 };
452 
453 static struct file_system_type hypfs_type = {
454 	.owner		= THIS_MODULE,
455 	.name		= "s390_hypfs",
456 	.mount		= hypfs_mount,
457 	.kill_sb	= hypfs_kill_super
458 };
459 
460 static const struct super_operations hypfs_s_ops = {
461 	.statfs		= simple_statfs,
462 	.evict_inode	= hypfs_evict_inode,
463 	.show_options	= hypfs_show_options,
464 };
465 
466 static struct kobject *s390_kobj;
467 
468 static int __init hypfs_init(void)
469 {
470 	int rc;
471 
472 	rc = hypfs_dbfs_init();
473 	if (rc)
474 		return rc;
475 	if (hypfs_diag_init()) {
476 		rc = -ENODATA;
477 		goto fail_dbfs_exit;
478 	}
479 	if (hypfs_vm_init()) {
480 		rc = -ENODATA;
481 		goto fail_hypfs_diag_exit;
482 	}
483 	s390_kobj = kobject_create_and_add("s390", hypervisor_kobj);
484 	if (!s390_kobj) {
485 		rc = -ENOMEM;
486 		goto fail_hypfs_vm_exit;
487 	}
488 	rc = register_filesystem(&hypfs_type);
489 	if (rc)
490 		goto fail_filesystem;
491 	return 0;
492 
493 fail_filesystem:
494 	kobject_put(s390_kobj);
495 fail_hypfs_vm_exit:
496 	hypfs_vm_exit();
497 fail_hypfs_diag_exit:
498 	hypfs_diag_exit();
499 fail_dbfs_exit:
500 	hypfs_dbfs_exit();
501 	pr_err("Initialization of hypfs failed with rc=%i\n", rc);
502 	return rc;
503 }
504 
505 static void __exit hypfs_exit(void)
506 {
507 	hypfs_diag_exit();
508 	hypfs_vm_exit();
509 	hypfs_dbfs_exit();
510 	unregister_filesystem(&hypfs_type);
511 	kobject_put(s390_kobj);
512 }
513 
514 module_init(hypfs_init)
515 module_exit(hypfs_exit)
516 
517 MODULE_LICENSE("GPL");
518 MODULE_AUTHOR("Michael Holzheu <holzheu@de.ibm.com>");
519 MODULE_DESCRIPTION("s390 Hypervisor Filesystem");
520