1/*
2 *    Hypervisor filesystem for Linux on s390.
3 *
4 *    Copyright IBM Corp. 2006, 2008
5 *    Author(s): Michael Holzheu <holzheu@de.ibm.com>
6 */
7
8#define KMSG_COMPONENT "hypfs"
9#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
10
11#include <linux/types.h>
12#include <linux/errno.h>
13#include <linux/fs.h>
14#include <linux/namei.h>
15#include <linux/vfs.h>
16#include <linux/slab.h>
17#include <linux/pagemap.h>
18#include <linux/time.h>
19#include <linux/parser.h>
20#include <linux/sysfs.h>
21#include <linux/module.h>
22#include <linux/seq_file.h>
23#include <linux/mount.h>
24#include <linux/uio.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
31static struct dentry *hypfs_create_update_file(struct dentry *dir);
32
33struct hypfs_sb_info {
34	kuid_t uid;			/* uid used for files and dirs */
35	kgid_t gid;			/* gid used for files and dirs */
36	struct dentry *update_file;	/* file to trigger update */
37	time_t last_update;		/* last update time in secs since 1970 */
38	struct mutex lock;		/* lock to protect update process */
39};
40
41static const struct file_operations hypfs_file_ops;
42static struct file_system_type hypfs_type;
43static const struct super_operations hypfs_s_ops;
44
45/* start of list of all dentries, which have to be deleted on update */
46static struct dentry *hypfs_last_dentry;
47
48static void hypfs_update_update(struct super_block *sb)
49{
50	struct hypfs_sb_info *sb_info = sb->s_fs_info;
51	struct inode *inode = d_inode(sb_info->update_file);
52
53	sb_info->last_update = get_seconds();
54	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
55}
56
57/* directory tree removal functions */
58
59static void hypfs_add_dentry(struct dentry *dentry)
60{
61	dentry->d_fsdata = hypfs_last_dentry;
62	hypfs_last_dentry = dentry;
63}
64
65static inline int hypfs_positive(struct dentry *dentry)
66{
67	return d_really_is_positive(dentry) && !d_unhashed(dentry);
68}
69
70static void hypfs_remove(struct dentry *dentry)
71{
72	struct dentry *parent;
73
74	parent = dentry->d_parent;
75	mutex_lock(&d_inode(parent)->i_mutex);
76	if (hypfs_positive(dentry)) {
77		if (d_is_dir(dentry))
78			simple_rmdir(d_inode(parent), dentry);
79		else
80			simple_unlink(d_inode(parent), dentry);
81	}
82	d_delete(dentry);
83	dput(dentry);
84	mutex_unlock(&d_inode(parent)->i_mutex);
85}
86
87static void hypfs_delete_tree(struct dentry *root)
88{
89	while (hypfs_last_dentry) {
90		struct dentry *next_dentry;
91		next_dentry = hypfs_last_dentry->d_fsdata;
92		hypfs_remove(hypfs_last_dentry);
93		hypfs_last_dentry = next_dentry;
94	}
95}
96
97static struct inode *hypfs_make_inode(struct super_block *sb, umode_t mode)
98{
99	struct inode *ret = new_inode(sb);
100
101	if (ret) {
102		struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
103		ret->i_ino = get_next_ino();
104		ret->i_mode = mode;
105		ret->i_uid = hypfs_info->uid;
106		ret->i_gid = hypfs_info->gid;
107		ret->i_atime = ret->i_mtime = ret->i_ctime = CURRENT_TIME;
108		if (S_ISDIR(mode))
109			set_nlink(ret, 2);
110	}
111	return ret;
112}
113
114static void hypfs_evict_inode(struct inode *inode)
115{
116	clear_inode(inode);
117	kfree(inode->i_private);
118}
119
120static int hypfs_open(struct inode *inode, struct file *filp)
121{
122	char *data = file_inode(filp)->i_private;
123	struct hypfs_sb_info *fs_info;
124
125	if (filp->f_mode & FMODE_WRITE) {
126		if (!(inode->i_mode & S_IWUGO))
127			return -EACCES;
128	}
129	if (filp->f_mode & FMODE_READ) {
130		if (!(inode->i_mode & S_IRUGO))
131			return -EACCES;
132	}
133
134	fs_info = inode->i_sb->s_fs_info;
135	if(data) {
136		mutex_lock(&fs_info->lock);
137		filp->private_data = kstrdup(data, GFP_KERNEL);
138		if (!filp->private_data) {
139			mutex_unlock(&fs_info->lock);
140			return -ENOMEM;
141		}
142		mutex_unlock(&fs_info->lock);
143	}
144	return nonseekable_open(inode, filp);
145}
146
147static ssize_t hypfs_read_iter(struct kiocb *iocb, struct iov_iter *to)
148{
149	struct file *file = iocb->ki_filp;
150	char *data = file->private_data;
151	size_t available = strlen(data);
152	loff_t pos = iocb->ki_pos;
153	size_t count;
154
155	if (pos < 0)
156		return -EINVAL;
157	if (pos >= available || !iov_iter_count(to))
158		return 0;
159	count = copy_to_iter(data + pos, available - pos, to);
160	if (!count)
161		return -EFAULT;
162	iocb->ki_pos = pos + count;
163	file_accessed(file);
164	return count;
165}
166
167static ssize_t hypfs_write_iter(struct kiocb *iocb, struct iov_iter *from)
168{
169	int rc;
170	struct super_block *sb = file_inode(iocb->ki_filp)->i_sb;
171	struct hypfs_sb_info *fs_info = sb->s_fs_info;
172	size_t count = iov_iter_count(from);
173
174	/*
175	 * Currently we only allow one update per second for two reasons:
176	 * 1. diag 204 is VERY expensive
177	 * 2. If several processes do updates in parallel and then read the
178	 *    hypfs data, the likelihood of collisions is reduced, if we restrict
179	 *    the minimum update interval. A collision occurs, if during the
180	 *    data gathering of one process another process triggers an update
181	 *    If the first process wants to ensure consistent data, it has
182	 *    to restart data collection in this case.
183	 */
184	mutex_lock(&fs_info->lock);
185	if (fs_info->last_update == get_seconds()) {
186		rc = -EBUSY;
187		goto out;
188	}
189	hypfs_delete_tree(sb->s_root);
190	if (MACHINE_IS_VM)
191		rc = hypfs_vm_create_files(sb->s_root);
192	else
193		rc = hypfs_diag_create_files(sb->s_root);
194	if (rc) {
195		pr_err("Updating the hypfs tree failed\n");
196		hypfs_delete_tree(sb->s_root);
197		goto out;
198	}
199	hypfs_update_update(sb);
200	rc = count;
201	iov_iter_advance(from, count);
202out:
203	mutex_unlock(&fs_info->lock);
204	return rc;
205}
206
207static int hypfs_release(struct inode *inode, struct file *filp)
208{
209	kfree(filp->private_data);
210	return 0;
211}
212
213enum { opt_uid, opt_gid, opt_err };
214
215static const match_table_t hypfs_tokens = {
216	{opt_uid, "uid=%u"},
217	{opt_gid, "gid=%u"},
218	{opt_err, NULL}
219};
220
221static int hypfs_parse_options(char *options, struct super_block *sb)
222{
223	char *str;
224	substring_t args[MAX_OPT_ARGS];
225	kuid_t uid;
226	kgid_t gid;
227
228	if (!options)
229		return 0;
230	while ((str = strsep(&options, ",")) != NULL) {
231		int token, option;
232		struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
233
234		if (!*str)
235			continue;
236		token = match_token(str, hypfs_tokens, args);
237		switch (token) {
238		case opt_uid:
239			if (match_int(&args[0], &option))
240				return -EINVAL;
241			uid = make_kuid(current_user_ns(), option);
242			if (!uid_valid(uid))
243				return -EINVAL;
244			hypfs_info->uid = uid;
245			break;
246		case opt_gid:
247			if (match_int(&args[0], &option))
248				return -EINVAL;
249			gid = make_kgid(current_user_ns(), option);
250			if (!gid_valid(gid))
251				return -EINVAL;
252			hypfs_info->gid = gid;
253			break;
254		case opt_err:
255		default:
256			pr_err("%s is not a valid mount option\n", str);
257			return -EINVAL;
258		}
259	}
260	return 0;
261}
262
263static int hypfs_show_options(struct seq_file *s, struct dentry *root)
264{
265	struct hypfs_sb_info *hypfs_info = root->d_sb->s_fs_info;
266
267	seq_printf(s, ",uid=%u", from_kuid_munged(&init_user_ns, hypfs_info->uid));
268	seq_printf(s, ",gid=%u", from_kgid_munged(&init_user_ns, hypfs_info->gid));
269	return 0;
270}
271
272static int hypfs_fill_super(struct super_block *sb, void *data, int silent)
273{
274	struct inode *root_inode;
275	struct dentry *root_dentry;
276	int rc = 0;
277	struct hypfs_sb_info *sbi;
278
279	sbi = kzalloc(sizeof(struct hypfs_sb_info), GFP_KERNEL);
280	if (!sbi)
281		return -ENOMEM;
282	mutex_init(&sbi->lock);
283	sbi->uid = current_uid();
284	sbi->gid = current_gid();
285	sb->s_fs_info = sbi;
286	sb->s_blocksize = PAGE_CACHE_SIZE;
287	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
288	sb->s_magic = HYPFS_MAGIC;
289	sb->s_op = &hypfs_s_ops;
290	if (hypfs_parse_options(data, sb))
291		return -EINVAL;
292	root_inode = hypfs_make_inode(sb, S_IFDIR | 0755);
293	if (!root_inode)
294		return -ENOMEM;
295	root_inode->i_op = &simple_dir_inode_operations;
296	root_inode->i_fop = &simple_dir_operations;
297	sb->s_root = root_dentry = d_make_root(root_inode);
298	if (!root_dentry)
299		return -ENOMEM;
300	if (MACHINE_IS_VM)
301		rc = hypfs_vm_create_files(root_dentry);
302	else
303		rc = hypfs_diag_create_files(root_dentry);
304	if (rc)
305		return rc;
306	sbi->update_file = hypfs_create_update_file(root_dentry);
307	if (IS_ERR(sbi->update_file))
308		return PTR_ERR(sbi->update_file);
309	hypfs_update_update(sb);
310	pr_info("Hypervisor filesystem mounted\n");
311	return 0;
312}
313
314static struct dentry *hypfs_mount(struct file_system_type *fst, int flags,
315			const char *devname, void *data)
316{
317	return mount_single(fst, flags, data, hypfs_fill_super);
318}
319
320static void hypfs_kill_super(struct super_block *sb)
321{
322	struct hypfs_sb_info *sb_info = sb->s_fs_info;
323
324	if (sb->s_root)
325		hypfs_delete_tree(sb->s_root);
326	if (sb_info->update_file)
327		hypfs_remove(sb_info->update_file);
328	kfree(sb->s_fs_info);
329	sb->s_fs_info = NULL;
330	kill_litter_super(sb);
331}
332
333static struct dentry *hypfs_create_file(struct dentry *parent, const char *name,
334					char *data, umode_t mode)
335{
336	struct dentry *dentry;
337	struct inode *inode;
338
339	mutex_lock(&d_inode(parent)->i_mutex);
340	dentry = lookup_one_len(name, parent, strlen(name));
341	if (IS_ERR(dentry)) {
342		dentry = ERR_PTR(-ENOMEM);
343		goto fail;
344	}
345	inode = hypfs_make_inode(parent->d_sb, mode);
346	if (!inode) {
347		dput(dentry);
348		dentry = ERR_PTR(-ENOMEM);
349		goto fail;
350	}
351	if (S_ISREG(mode)) {
352		inode->i_fop = &hypfs_file_ops;
353		if (data)
354			inode->i_size = strlen(data);
355		else
356			inode->i_size = 0;
357	} else if (S_ISDIR(mode)) {
358		inode->i_op = &simple_dir_inode_operations;
359		inode->i_fop = &simple_dir_operations;
360		inc_nlink(d_inode(parent));
361	} else
362		BUG();
363	inode->i_private = data;
364	d_instantiate(dentry, inode);
365	dget(dentry);
366fail:
367	mutex_unlock(&d_inode(parent)->i_mutex);
368	return dentry;
369}
370
371struct dentry *hypfs_mkdir(struct dentry *parent, const char *name)
372{
373	struct dentry *dentry;
374
375	dentry = hypfs_create_file(parent, name, NULL, S_IFDIR | DIR_MODE);
376	if (IS_ERR(dentry))
377		return dentry;
378	hypfs_add_dentry(dentry);
379	return dentry;
380}
381
382static struct dentry *hypfs_create_update_file(struct dentry *dir)
383{
384	struct dentry *dentry;
385
386	dentry = hypfs_create_file(dir, "update", NULL,
387				   S_IFREG | UPDATE_FILE_MODE);
388	/*
389	 * We do not put the update file on the 'delete' list with
390	 * hypfs_add_dentry(), since it should not be removed when the tree
391	 * is updated.
392	 */
393	return dentry;
394}
395
396struct dentry *hypfs_create_u64(struct dentry *dir,
397				const char *name, __u64 value)
398{
399	char *buffer;
400	char tmp[TMP_SIZE];
401	struct dentry *dentry;
402
403	snprintf(tmp, TMP_SIZE, "%llu\n", (unsigned long long int)value);
404	buffer = kstrdup(tmp, GFP_KERNEL);
405	if (!buffer)
406		return ERR_PTR(-ENOMEM);
407	dentry =
408	    hypfs_create_file(dir, name, buffer, S_IFREG | REG_FILE_MODE);
409	if (IS_ERR(dentry)) {
410		kfree(buffer);
411		return ERR_PTR(-ENOMEM);
412	}
413	hypfs_add_dentry(dentry);
414	return dentry;
415}
416
417struct dentry *hypfs_create_str(struct dentry *dir,
418				const char *name, char *string)
419{
420	char *buffer;
421	struct dentry *dentry;
422
423	buffer = kmalloc(strlen(string) + 2, GFP_KERNEL);
424	if (!buffer)
425		return ERR_PTR(-ENOMEM);
426	sprintf(buffer, "%s\n", string);
427	dentry =
428	    hypfs_create_file(dir, name, buffer, S_IFREG | REG_FILE_MODE);
429	if (IS_ERR(dentry)) {
430		kfree(buffer);
431		return ERR_PTR(-ENOMEM);
432	}
433	hypfs_add_dentry(dentry);
434	return dentry;
435}
436
437static const struct file_operations hypfs_file_ops = {
438	.open		= hypfs_open,
439	.release	= hypfs_release,
440	.read_iter	= hypfs_read_iter,
441	.write_iter	= hypfs_write_iter,
442	.llseek		= no_llseek,
443};
444
445static struct file_system_type hypfs_type = {
446	.owner		= THIS_MODULE,
447	.name		= "s390_hypfs",
448	.mount		= hypfs_mount,
449	.kill_sb	= hypfs_kill_super
450};
451MODULE_ALIAS_FS("s390_hypfs");
452
453static const struct super_operations hypfs_s_ops = {
454	.statfs		= simple_statfs,
455	.evict_inode	= hypfs_evict_inode,
456	.show_options	= hypfs_show_options,
457};
458
459static int __init hypfs_init(void)
460{
461	int rc;
462
463	rc = hypfs_dbfs_init();
464	if (rc)
465		return rc;
466	if (hypfs_diag_init()) {
467		rc = -ENODATA;
468		goto fail_dbfs_exit;
469	}
470	if (hypfs_vm_init()) {
471		rc = -ENODATA;
472		goto fail_hypfs_diag_exit;
473	}
474	if (hypfs_sprp_init()) {
475		rc = -ENODATA;
476		goto fail_hypfs_vm_exit;
477	}
478	if (hypfs_diag0c_init()) {
479		rc = -ENODATA;
480		goto fail_hypfs_sprp_exit;
481	}
482	rc = sysfs_create_mount_point(hypervisor_kobj, "s390");
483	if (rc)
484		goto fail_hypfs_diag0c_exit;
485	rc = register_filesystem(&hypfs_type);
486	if (rc)
487		goto fail_filesystem;
488	return 0;
489
490fail_filesystem:
491	sysfs_remove_mount_point(hypervisor_kobj, "s390");
492fail_hypfs_diag0c_exit:
493	hypfs_diag0c_exit();
494fail_hypfs_sprp_exit:
495	hypfs_sprp_exit();
496fail_hypfs_vm_exit:
497	hypfs_vm_exit();
498fail_hypfs_diag_exit:
499	hypfs_diag_exit();
500fail_dbfs_exit:
501	hypfs_dbfs_exit();
502	pr_err("Initialization of hypfs failed with rc=%i\n", rc);
503	return rc;
504}
505
506static void __exit hypfs_exit(void)
507{
508	unregister_filesystem(&hypfs_type);
509	sysfs_remove_mount_point(hypervisor_kobj, "s390");
510	hypfs_diag0c_exit();
511	hypfs_sprp_exit();
512	hypfs_vm_exit();
513	hypfs_diag_exit();
514	hypfs_dbfs_exit();
515}
516
517module_init(hypfs_init)
518module_exit(hypfs_exit)
519
520MODULE_LICENSE("GPL");
521MODULE_AUTHOR("Michael Holzheu <holzheu@de.ibm.com>");
522MODULE_DESCRIPTION("s390 Hypervisor Filesystem");
523