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